[thirdparty/cups.git] / cups / http.c

/*
 * HTTP routines for CUPS.
 *
 * Copyright 2007-2018 by Apple Inc.
 * Copyright 1997-2007 by Easy Software Products, all rights reserved.
 *
 * This file contains Kerberos support code, copyright 2006 by
 * Jelmer Vernooij.
 *
 * Licensed under Apache License v2.0.  See the file "LICENSE" for more
 * information.
 */

/*
 * Include necessary headers...
 */

#include "cups-private.h"
#include <fcntl.h>
#include <math.h>
#ifdef WIN32
#  include <tchar.h>
#else
#  include <signal.h>
#  include <sys/time.h>
#  include <sys/resource.h>
#endif /* WIN32 */
#ifdef HAVE_POLL
#  include <poll.h>
#endif /* HAVE_POLL */


/*
 * Local functions...
 */

static void             http_add_field(http_t *http, http_field_t field, const char *value, int append);
#ifdef HAVE_LIBZ
static void             http_content_coding_finish(http_t *http);
static void             http_content_coding_start(http_t *http,
                                                  const char *value);
#endif /* HAVE_LIBZ */
static http_t           *http_create(const char *host, int port,
                                     http_addrlist_t *addrlist, int family,
                                     http_encryption_t encryption,
                                     int blocking, _http_mode_t mode);
#ifdef DEBUG
static void             http_debug_hex(const char *prefix, const char *buffer,
                                       int bytes);
#endif /* DEBUG */
static ssize_t          http_read(http_t *http, char *buffer, size_t length);
static ssize_t          http_read_buffered(http_t *http, char *buffer, size_t length);
static ssize_t          http_read_chunk(http_t *http, char *buffer, size_t length);
static int              http_send(http_t *http, http_state_t request,
                                  const char *uri);
static ssize_t          http_write(http_t *http, const char *buffer,
                                   size_t length);
static ssize_t          http_write_chunk(http_t *http, const char *buffer,
                                         size_t length);
static off_t            http_set_length(http_t *http);
static void             http_set_timeout(int fd, double timeout);
static void             http_set_wait(http_t *http);

#ifdef HAVE_SSL
static int              http_tls_upgrade(http_t *http);
#endif /* HAVE_SSL */


/*
 * Local globals...
 */

static const char * const http_fields[] =
                        {
                          "Accept-Language",
                          "Accept-Ranges",
                          "Authorization",
                          "Connection",
                          "Content-Encoding",
                          "Content-Language",
                          "Content-Length",
                          "Content-Location",
                          "Content-MD5",
                          "Content-Range",
                          "Content-Type",
                          "Content-Version",
                          "Date",
                          "Host",
                          "If-Modified-Since",
                          "If-Unmodified-since",
                          "Keep-Alive",
                          "Last-Modified",
                          "Link",
                          "Location",
                          "Range",
                          "Referer",
                          "Retry-After",
                          "Transfer-Encoding",
                          "Upgrade",
                          "User-Agent",
                          "WWW-Authenticate",
                          "Accept-Encoding",
                          "Allow",
                          "Server",
                          "Authentication-Info"
                        };


/*
 * 'httpAcceptConnection()' - Accept a new HTTP client connection from the
 *                            specified listening socket.
 *
 * @since CUPS 1.7/macOS 10.9@
 */

http_t *                                /* O - HTTP connection or @code NULL@ */
httpAcceptConnection(int fd,            /* I - Listen socket file descriptor */
                     int blocking)      /* I - 1 if the connection should be
                                               blocking, 0 otherwise */
{
  http_t                *http;          /* HTTP connection */
  http_addrlist_t       addrlist;       /* Dummy address list */
  socklen_t             addrlen;        /* Length of address */
  int                   val;            /* Socket option value */


 /*
  * Range check input...
  */

  if (fd < 0)
    return (NULL);

 /*
  * Create the client connection...
  */

  memset(&addrlist, 0, sizeof(addrlist));

  if ((http = http_create(NULL, 0, &addrlist, AF_UNSPEC,
                          HTTP_ENCRYPTION_IF_REQUESTED, blocking,
                          _HTTP_MODE_SERVER)) == NULL)
    return (NULL);

 /*
  * Accept the client and get the remote address...
  */

  addrlen = sizeof(http_addr_t);

  if ((http->fd = accept(fd, (struct sockaddr *)&(http->addrlist->addr),
                         &addrlen)) < 0)
  {
    _cupsSetHTTPError(HTTP_STATUS_ERROR);
    httpClose(http);

    return (NULL);
  }

  http->hostaddr = &(http->addrlist->addr);

  if (httpAddrLocalhost(http->hostaddr))
    strlcpy(http->hostname, "localhost", sizeof(http->hostname));
  else
    httpAddrString(http->hostaddr, http->hostname, sizeof(http->hostname));

#ifdef SO_NOSIGPIPE
 /*
  * Disable SIGPIPE for this socket.
  */

  val = 1;
  setsockopt(http->fd, SOL_SOCKET, SO_NOSIGPIPE, CUPS_SOCAST &val, sizeof(val));
#endif /* SO_NOSIGPIPE */

 /*
  * Using TCP_NODELAY improves responsiveness, especially on systems
  * with a slow loopback interface.  Since we write large buffers
  * when sending print files and requests, there shouldn't be any
  * performance penalty for this...
  */

  val = 1;
  setsockopt(http->fd, IPPROTO_TCP, TCP_NODELAY, CUPS_SOCAST &val, sizeof(val));

#ifdef FD_CLOEXEC
 /*
  * Close this socket when starting another process...
  */

  fcntl(http->fd, F_SETFD, FD_CLOEXEC);
#endif /* FD_CLOEXEC */

  return (http);
}


/*
 * 'httpAddCredential()' - Allocates and adds a single credential to an array.
 *
 * Use @code cupsArrayNew(NULL, NULL)@ to create a credentials array.
 *
 * @since CUPS 1.5/macOS 10.7@
 */

int                                     /* O - 0 on success, -1 on error */
httpAddCredential(
    cups_array_t *credentials,          /* I - Credentials array */
    const void   *data,                 /* I - PEM-encoded X.509 data */
    size_t       datalen)               /* I - Length of data */
{
  http_credential_t     *credential;    /* Credential data */


  if ((credential = malloc(sizeof(http_credential_t))) != NULL)
  {
    credential->datalen = datalen;

    if ((credential->data = malloc(datalen)) != NULL)
    {
      memcpy(credential->data, data, datalen);
      cupsArrayAdd(credentials, credential);
      return (0);
    }

    free(credential);
  }

  return (-1);
}


/*
 * 'httpBlocking()' - Set blocking/non-blocking behavior on a connection.
 */

void
httpBlocking(http_t *http,              /* I - HTTP connection */
             int    b)                  /* I - 1 = blocking, 0 = non-blocking */
{
  if (http)
  {
    http->blocking = b;
    http_set_wait(http);
  }
}


/*
 * 'httpCheck()' - Check to see if there is a pending response from the server.
 */

int                                     /* O - 0 = no data, 1 = data available */
httpCheck(http_t *http)                 /* I - HTTP connection */
{
  return (httpWait(http, 0));
}


/*
 * 'httpClearCookie()' - Clear the cookie value(s).
 *
 * @since CUPS 1.1.19/macOS 10.3@
 */

void
httpClearCookie(http_t *http)           /* I - HTTP connection */
{
  if (!http)
    return;

  if (http->cookie)
  {
    free(http->cookie);
    http->cookie = NULL;
  }
}


/*
 * 'httpClearFields()' - Clear HTTP request fields.
 */

void
httpClearFields(http_t *http)           /* I - HTTP connection */
{
  http_field_t  field;                  /* Current field */


  DEBUG_printf(("httpClearFields(http=%p)", (void *)http));

  if (http)
  {
    memset(http->_fields, 0, sizeof(http->fields));

    for (field = HTTP_FIELD_ACCEPT_LANGUAGE; field < HTTP_FIELD_MAX; field ++)
    {
      if (http->fields[field] && http->fields[field] != http->_fields[field])
        free(http->fields[field]);

      http->fields[field] = NULL;
    }

    if (http->mode == _HTTP_MODE_CLIENT)
    {
      if (http->hostname[0] == '/')
        httpSetField(http, HTTP_FIELD_HOST, "localhost");
      else
        httpSetField(http, HTTP_FIELD_HOST, http->hostname);
    }

    http->expect = (http_status_t)0;
  }
}


/*
 * 'httpClose()' - Close an HTTP connection.
 */

void
httpClose(http_t *http)                 /* I - HTTP connection */
{
#ifdef HAVE_GSSAPI
  OM_uint32     minor_status;           /* Minor status code */
#endif /* HAVE_GSSAPI */


  DEBUG_printf(("httpClose(http=%p)", (void *)http));

 /*
  * Range check input...
  */

  if (!http)
    return;

 /*
  * Close any open connection...
  */

  _httpDisconnect(http);

 /*
  * Free memory used...
  */

  httpAddrFreeList(http->addrlist);

  if (http->cookie)
    free(http->cookie);

#ifdef HAVE_GSSAPI
  if (http->gssctx != GSS_C_NO_CONTEXT)
    gss_delete_sec_context(&minor_status, &http->gssctx, GSS_C_NO_BUFFER);

  if (http->gssname != GSS_C_NO_NAME)
    gss_release_name(&minor_status, &http->gssname);
#endif /* HAVE_GSSAPI */

#ifdef HAVE_AUTHORIZATION_H
  if (http->auth_ref)
    AuthorizationFree(http->auth_ref, kAuthorizationFlagDefaults);
#endif /* HAVE_AUTHORIZATION_H */

  httpClearFields(http);

  if (http->authstring && http->authstring != http->_authstring)
    free(http->authstring);

  free(http);
}


/*
 * 'httpCompareCredentials()' - Compare two sets of X.509 credentials.
 *
 * @since CUPS 2.0/OS 10.10@
 */

int                                     /* O - 1 if they match, 0 if they do not */
httpCompareCredentials(
    cups_array_t *cred1,                /* I - First set of X.509 credentials */
    cups_array_t *cred2)                /* I - Second set of X.509 credentials */
{
  http_credential_t     *temp1, *temp2; /* Temporary credentials */


  for (temp1 = (http_credential_t *)cupsArrayFirst(cred1), temp2 = (http_credential_t *)cupsArrayFirst(cred2); temp1 && temp2; temp1 = (http_credential_t *)cupsArrayNext(cred1), temp2 = (http_credential_t *)cupsArrayNext(cred2))
    if (temp1->datalen != temp2->datalen)
      return (0);
    else if (memcmp(temp1->data, temp2->data, temp1->datalen))
      return (0);

  return (temp1 == temp2);
}


/*
 * 'httpConnect()' - Connect to a HTTP server.
 *
 * This function is deprecated - use @link httpConnect2@ instead.
 *
 * @deprecated@ @exclude all@
 */

http_t *                                /* O - New HTTP connection */
httpConnect(const char *host,           /* I - Host to connect to */
            int        port)            /* I - Port number */
{
  return (httpConnect2(host, port, NULL, AF_UNSPEC,
                       HTTP_ENCRYPTION_IF_REQUESTED, 1, 30000, NULL));
}


/*
 * 'httpConnect2()' - Connect to a HTTP server.
 *
 * @since CUPS 1.7/macOS 10.9@
 */

http_t *                                /* O - New HTTP connection */
httpConnect2(
    const char        *host,            /* I - Host to connect to */
    int               port,             /* I - Port number */
    http_addrlist_t   *addrlist,        /* I - List of addresses or @code NULL@ to lookup */
    int               family,           /* I - Address family to use or @code AF_UNSPEC@ for any */
    http_encryption_t encryption,       /* I - Type of encryption to use */
    int               blocking,         /* I - 1 for blocking connection, 0 for non-blocking */
    int               msec,             /* I - Connection timeout in milliseconds, 0 means don't connect */
    int               *cancel)          /* I - Pointer to "cancel" variable */
{
  http_t        *http;                  /* New HTTP connection */


  DEBUG_printf(("httpConnect2(host=\"%s\", port=%d, addrlist=%p, family=%d, encryption=%d, blocking=%d, msec=%d, cancel=%p)", host, port, (void *)addrlist, family, encryption, blocking, msec, (void *)cancel));

 /*
  * Create the HTTP structure...
  */

  if ((http = http_create(host, port, addrlist, family, encryption, blocking,
                          _HTTP_MODE_CLIENT)) == NULL)
    return (NULL);

 /*
  * Optionally connect to the remote system...
  */

  if (msec == 0 || !httpReconnect2(http, msec, cancel))
    return (http);

 /*
  * Could not connect to any known address - bail out!
  */

  httpClose(http);

  return (NULL);
}


/*
 * 'httpConnectEncrypt()' - Connect to a HTTP server using encryption.
 *
 * This function is now deprecated. Please use the @link httpConnect2@ function
 * instead.
 *
 * @deprecated@ @exclude all@
 */

http_t *                                /* O - New HTTP connection */
httpConnectEncrypt(
    const char        *host,            /* I - Host to connect to */
    int               port,             /* I - Port number */
    http_encryption_t encryption)       /* I - Type of encryption to use */
{
  DEBUG_printf(("httpConnectEncrypt(host=\"%s\", port=%d, encryption=%d)",
                host, port, encryption));

  return (httpConnect2(host, port, NULL, AF_UNSPEC, encryption, 1, 30000,
                       NULL));
}


/*
 * 'httpDelete()' - Send a DELETE request to the server.
 */

int                                     /* O - Status of call (0 = success) */
httpDelete(http_t     *http,            /* I - HTTP connection */
           const char *uri)             /* I - URI to delete */
{
  return (http_send(http, HTTP_STATE_DELETE, uri));
}


/*
 * '_httpDisconnect()' - Disconnect a HTTP connection.
 */

void
_httpDisconnect(http_t *http)           /* I - HTTP connection */
{
#ifdef HAVE_SSL
  if (http->tls)
    _httpTLSStop(http);
#endif /* HAVE_SSL */

  httpAddrClose(NULL, http->fd);

  http->fd = -1;
}


/*
 * 'httpEncryption()' - Set the required encryption on the link.
 */

int                                     /* O - -1 on error, 0 on success */
httpEncryption(http_t            *http, /* I - HTTP connection */
               http_encryption_t e)     /* I - New encryption preference */
{
  DEBUG_printf(("httpEncryption(http=%p, e=%d)", (void *)http, e));

#ifdef HAVE_SSL
  if (!http)
    return (0);

  if (http->mode == _HTTP_MODE_CLIENT)
  {
    http->encryption = e;

    if ((http->encryption == HTTP_ENCRYPTION_ALWAYS && !http->tls) ||
        (http->encryption == HTTP_ENCRYPTION_NEVER && http->tls))
      return (httpReconnect2(http, 30000, NULL));
    else if (http->encryption == HTTP_ENCRYPTION_REQUIRED && !http->tls)
      return (http_tls_upgrade(http));
    else
      return (0);
  }
  else
  {
    if (e == HTTP_ENCRYPTION_NEVER && http->tls)
      return (-1);

    http->encryption = e;
    if (e != HTTP_ENCRYPTION_IF_REQUESTED && !http->tls)
      return (_httpTLSStart(http));
    else
      return (0);
  }
#else
  if (e == HTTP_ENCRYPTION_ALWAYS || e == HTTP_ENCRYPTION_REQUIRED)
    return (-1);
  else
    return (0);
#endif /* HAVE_SSL */
}


/*
 * 'httpError()' - Get the last error on a connection.
 */

int                                     /* O - Error code (errno) value */
httpError(http_t *http)                 /* I - HTTP connection */
{
  if (http)
    return (http->error);
  else
    return (EINVAL);
}


/*
 * 'httpFieldValue()' - Return the HTTP field enumeration value for a field
 *                      name.
 */

http_field_t                            /* O - Field index */
httpFieldValue(const char *name)        /* I - String name */
{
  int   i;                              /* Looping var */


  for (i = 0; i < HTTP_FIELD_MAX; i ++)
    if (!_cups_strcasecmp(name, http_fields[i]))
      return ((http_field_t)i);

  return (HTTP_FIELD_UNKNOWN);
}


/*
 * 'httpFlush()' - Flush data read from a HTTP connection.
 */

void
httpFlush(http_t *http)                 /* I - HTTP connection */
{
  char          buffer[8192];           /* Junk buffer */
  int           blocking;               /* To block or not to block */
  http_state_t  oldstate;               /* Old state */


  DEBUG_printf(("httpFlush(http=%p), state=%s", (void *)http, httpStateString(http->state)));

 /*
  * Nothing to do if we are in the "waiting" state...
  */

  if (http->state == HTTP_STATE_WAITING)
    return;

 /*
  * Temporarily set non-blocking mode so we don't get stuck in httpRead()...
  */

  blocking = http->blocking;
  http->blocking = 0;

 /*
  * Read any data we can...
  */

  oldstate = http->state;
  while (httpRead2(http, buffer, sizeof(buffer)) > 0);

 /*
  * Restore blocking and reset the connection if we didn't get all of
  * the remaining data...
  */

  http->blocking = blocking;

  if (http->state == oldstate && http->state != HTTP_STATE_WAITING &&
      http->fd >= 0)
  {
   /*
    * Didn't get the data back, so close the current connection.
    */

#ifdef HAVE_LIBZ
    if (http->coding)
      http_content_coding_finish(http);
#endif /* HAVE_LIBZ */

    DEBUG_puts("1httpFlush: Setting state to HTTP_STATE_WAITING and closing.");

    http->state = HTTP_STATE_WAITING;

#ifdef HAVE_SSL
    if (http->tls)
      _httpTLSStop(http);
#endif /* HAVE_SSL */

    httpAddrClose(NULL, http->fd);

    http->fd = -1;
  }
}


/*
 * 'httpFlushWrite()' - Flush data written to a HTTP connection.
 *
 * @since CUPS 1.2/macOS 10.5@
 */

int                                     /* O - Bytes written or -1 on error */
httpFlushWrite(http_t *http)            /* I - HTTP connection */
{
  ssize_t       bytes;                  /* Bytes written */


  DEBUG_printf(("httpFlushWrite(http=%p) data_encoding=%d", (void *)http, http ? http->data_encoding : 100));

  if (!http || !http->wused)
  {
    DEBUG_puts(http ? "1httpFlushWrite: Write buffer is empty." :
                      "1httpFlushWrite: No connection.");
    return (0);
  }

  if (http->data_encoding == HTTP_ENCODING_CHUNKED)
    bytes = http_write_chunk(http, http->wbuffer, (size_t)http->wused);
  else
    bytes = http_write(http, http->wbuffer, (size_t)http->wused);

  http->wused = 0;

  DEBUG_printf(("1httpFlushWrite: Returning %d, errno=%d.", (int)bytes, errno));

  return ((int)bytes);
}


/*
 * 'httpFreeCredentials()' - Free an array of credentials.
 */

void
httpFreeCredentials(
    cups_array_t *credentials)          /* I - Array of credentials */
{
  http_credential_t     *credential;    /* Credential */


  for (credential = (http_credential_t *)cupsArrayFirst(credentials);
       credential;
       credential = (http_credential_t *)cupsArrayNext(credentials))
  {
    cupsArrayRemove(credentials, credential);
    free((void *)credential->data);
    free(credential);
  }

  cupsArrayDelete(credentials);
}


/*
 * 'httpGet()' - Send a GET request to the server.
 */

int                                     /* O - Status of call (0 = success) */
httpGet(http_t     *http,               /* I - HTTP connection */
        const char *uri)                /* I - URI to get */
{
  return (http_send(http, HTTP_STATE_GET, uri));
}


/*
 * 'httpGetActivity()' - Get the most recent activity for a connection.
 *
 * The return value is the time in seconds of the last read or write.
 *
 * @since CUPS 2.0/OS 10.10@
 */

time_t                                  /* O - Time of last read or write */
httpGetActivity(http_t *http)           /* I - HTTP connection */
{
  return (http ? http->activity : 0);
}


/*
 * 'httpGetAuthString()' - Get the current authorization string.
 *
 * The authorization string is set by @link cupsDoAuthentication@ and
 * @link httpSetAuthString@.  Use @link httpGetAuthString@ to retrieve the
 * string to use with @link httpSetField@ for the
 * @code HTTP_FIELD_AUTHORIZATION@ value.
 *
 * @since CUPS 1.3/macOS 10.5@
 */

char *                                  /* O - Authorization string */
httpGetAuthString(http_t *http)         /* I - HTTP connection */
{
  if (http)
    return (http->authstring);
  else
    return (NULL);
}


/*
 * 'httpGetBlocking()' - Get the blocking/non-block state of a connection.
 *
 * @since CUPS 1.2/macOS 10.5@
 */

int                                     /* O - 1 if blocking, 0 if non-blocking */
httpGetBlocking(http_t *http)           /* I - HTTP connection */
{
  return (http ? http->blocking : 0);
}


/*
 * 'httpGetContentEncoding()' - Get a common content encoding, if any, between
 *                              the client and server.
 *
 * This function uses the value of the Accepts-Encoding HTTP header and must be
 * called after receiving a response from the server or a request from the
 * client.  The value returned can be use in subsequent requests (for clients)
 * or in the response (for servers) in order to compress the content stream.
 *
 * @since CUPS 1.7/macOS 10.9@
 */

const char *                            /* O - Content-Coding value or
                                               @code NULL@ for the identity
                                               coding. */
httpGetContentEncoding(http_t *http)    /* I - HTTP connection */
{
#ifdef HAVE_LIBZ
  if (http && http->fields[HTTP_FIELD_ACCEPT_ENCODING])
  {
    int         i;                      /* Looping var */
    char        temp[HTTP_MAX_VALUE],   /* Copy of Accepts-Encoding value */
                *start,                 /* Start of coding value */
                *end;                   /* End of coding value */
    double      qvalue;                 /* "qvalue" for coding */
    struct lconv *loc = localeconv();   /* Locale data */
    static const char * const codings[] =
    {                                   /* Supported content codings */
      "deflate",
      "gzip",
      "x-deflate",
      "x-gzip"
    };

    strlcpy(temp, http->fields[HTTP_FIELD_ACCEPT_ENCODING], sizeof(temp));

    for (start = temp; *start; start = end)
    {
     /*
      * Find the end of the coding name...
      */

      qvalue = 1.0;
      end    = start;
      while (*end && *end != ';' && *end != ',' && !isspace(*end & 255))
        end ++;

      if (*end == ';')
      {
       /*
        * Grab the qvalue as needed...
        */

        if (!strncmp(end, ";q=", 3))
          qvalue = _cupsStrScand(end + 3, NULL, loc);

       /*
        * Skip past all attributes...
        */

        *end++ = '\0';
        while (*end && *end != ',' && !isspace(*end & 255))
          end ++;
      }
      else if (*end)
        *end++ = '\0';

      while (*end && isspace(*end & 255))
        end ++;

     /*
      * Check value if it matches something we support...
      */

      if (qvalue <= 0.0)
        continue;

      for (i = 0; i < (int)(sizeof(codings) / sizeof(codings[0])); i ++)
        if (!strcmp(start, codings[i]))
          return (codings[i]);
    }
  }
#endif /* HAVE_LIBZ */

  return (NULL);
}


/*
 * 'httpGetCookie()' - Get any cookie data from the response.
 *
 * @since CUPS 1.1.19/macOS 10.3@
 */

const char *                            /* O - Cookie data or @code NULL@ */
httpGetCookie(http_t *http)             /* I - HTTP connection */
{
  return (http ? http->cookie : NULL);
}


/*
 * 'httpGetEncryption()' - Get the current encryption mode of a connection.
 *
 * This function returns the encryption mode for the connection. Use the
 * @link httpIsEncrypted@ function to determine whether a TLS session has
 * been established.
 *
 * @since CUPS 2.0/OS 10.10@
 */

http_encryption_t                       /* O - Current encryption mode */
httpGetEncryption(http_t *http)         /* I - HTTP connection */
{
  return (http ? http->encryption : HTTP_ENCRYPTION_IF_REQUESTED);
}


/*
 * 'httpGetExpect()' - Get the value of the Expect header, if any.
 *
 * Returns @code HTTP_STATUS_NONE@ if there is no Expect header, otherwise
 * returns the expected HTTP status code, typically @code HTTP_STATUS_CONTINUE@.
 *
 * @since CUPS 1.7/macOS 10.9@
 */

http_status_t                           /* O - Expect: status, if any */
httpGetExpect(http_t *http)             /* I - HTTP connection */
{
  if (!http)
    return (HTTP_STATUS_ERROR);
  else
    return (http->expect);
}


/*
 * 'httpGetFd()' - Get the file descriptor associated with a connection.
 *
 * @since CUPS 1.2/macOS 10.5@
 */

int                                     /* O - File descriptor or -1 if none */
httpGetFd(http_t *http)                 /* I - HTTP connection */
{
  return (http ? http->fd : -1);
}


/*
 * 'httpGetField()' - Get a field value from a request/response.
 */

const char *                            /* O - Field value */
httpGetField(http_t       *http,        /* I - HTTP connection */
             http_field_t field)        /* I - Field to get */
{
  if (!http || field <= HTTP_FIELD_UNKNOWN || field >= HTTP_FIELD_MAX)
    return (NULL);
  else if (http->fields[field])
    return (http->fields[field]);
  else
    return ("");
}


/*
 * 'httpGetKeepAlive()' - Get the current Keep-Alive state of the connection.
 *
 * @since CUPS 2.0/OS 10.10@
 */

http_keepalive_t                        /* O - Keep-Alive state */
httpGetKeepAlive(http_t *http)          /* I - HTTP connection */
{
  return (http ? http->keep_alive : HTTP_KEEPALIVE_OFF);
}


/*
 * 'httpGetLength()' - Get the amount of data remaining from the
 *                     content-length or transfer-encoding fields.
 *
 * This function is deprecated and will not return lengths larger than
 * 2^31 - 1; use httpGetLength2() instead.
 *
 * @deprecated@ @exclude all@
 */

int                                     /* O - Content length */
httpGetLength(http_t *http)             /* I - HTTP connection */
{
 /*
  * Get the read content length and return the 32-bit value.
  */

  if (http)
  {
    httpGetLength2(http);

    return (http->_data_remaining);
  }
  else
    return (-1);
}


/*
 * 'httpGetLength2()' - Get the amount of data remaining from the
 *                      content-length or transfer-encoding fields.
 *
 * This function returns the complete content length, even for
 * content larger than 2^31 - 1.
 *
 * @since CUPS 1.2/macOS 10.5@
 */

off_t                                   /* O - Content length */
httpGetLength2(http_t *http)            /* I - HTTP connection */
{
  off_t                 remaining;      /* Remaining length */


  DEBUG_printf(("2httpGetLength2(http=%p), state=%s", (void *)http, httpStateString(http->state)));

  if (!http)
    return (-1);

  if (http->fields[HTTP_FIELD_TRANSFER_ENCODING] && !_cups_strcasecmp(http->fields[HTTP_FIELD_TRANSFER_ENCODING], "chunked"))
  {
    DEBUG_puts("4httpGetLength2: chunked request!");
    remaining = 0;
  }
  else
  {
   /*
    * The following is a hack for HTTP servers that don't send a
    * Content-Length or Transfer-Encoding field...
    *
    * If there is no Content-Length then the connection must close
    * after the transfer is complete...
    */

    if (!http->fields[HTTP_FIELD_CONTENT_LENGTH] || !http->fields[HTTP_FIELD_CONTENT_LENGTH][0])
    {
     /*
      * Default content length is 0 for errors and certain types of operations,
      * and 2^31-1 for other successful requests...
      */

      if (http->status >= HTTP_STATUS_MULTIPLE_CHOICES ||
          http->state == HTTP_STATE_OPTIONS ||
          (http->state == HTTP_STATE_GET && http->mode == _HTTP_MODE_SERVER) ||
          http->state == HTTP_STATE_HEAD ||
          (http->state == HTTP_STATE_PUT && http->mode == _HTTP_MODE_CLIENT) ||
          http->state == HTTP_STATE_DELETE ||
          http->state == HTTP_STATE_TRACE ||
          http->state == HTTP_STATE_CONNECT)
        remaining = 0;
      else
        remaining = 2147483647;
    }
    else if ((remaining = strtoll(http->fields[HTTP_FIELD_CONTENT_LENGTH],
                                  NULL, 10)) < 0)
      remaining = -1;

    DEBUG_printf(("4httpGetLength2: content_length=" CUPS_LLFMT,
                  CUPS_LLCAST remaining));
  }

  return (remaining);
}


/*
 * 'httpGetPending()' - Get the number of bytes that are buffered for writing.
 *
 * @since CUPS 2.0/OS 10.10@
 */

size_t                                  /* O - Number of bytes buffered */
httpGetPending(http_t *http)            /* I - HTTP connection */
{
  return (http ? (size_t)http->wused : 0);
}


/*
 * 'httpGetReady()' - Get the number of bytes that can be read without blocking.
 *
 * @since CUPS 2.0/OS 10.10@
 */

size_t                                  /* O - Number of bytes available */
httpGetReady(http_t *http)              /* I - HTTP connection */
{
  if (!http)
    return (0);
  else if (http->used > 0)
    return ((size_t)http->used);
#ifdef HAVE_SSL
  else if (http->tls)
    return (_httpTLSPending(http));
#endif /* HAVE_SSL */

  return (0);
}


/*
 * 'httpGetRemaining()' - Get the number of remaining bytes in the message
 *                        body or current chunk.
 *
 * The @link httpIsChunked@ function can be used to determine whether the
 * message body is chunked or fixed-length.
 *
 * @since CUPS 2.0/OS 10.10@
 */

size_t                                  /* O - Remaining bytes */
httpGetRemaining(http_t *http)          /* I - HTTP connection */
{
  return (http ? (size_t)http->data_remaining : 0);
}


/*
 * 'httpGets()' - Get a line of text from a HTTP connection.
 */

char *                                  /* O - Line or @code NULL@ */
httpGets(char   *line,                  /* I - Line to read into */
         int    length,                 /* I - Max length of buffer */
         http_t *http)                  /* I - HTTP connection */
{
  char          *lineptr,               /* Pointer into line */
                *lineend,               /* End of line */
                *bufptr,                /* Pointer into input buffer */
                *bufend;                /* Pointer to end of buffer */
  ssize_t       bytes;                  /* Number of bytes read */
  int           eol;                    /* End-of-line? */


  DEBUG_printf(("2httpGets(line=%p, length=%d, http=%p)", (void *)line, length, (void *)http));

  if (!http || !line || length <= 1)
    return (NULL);

 /*
  * Read a line from the buffer...
  */

  http->error = 0;
  lineptr     = line;
  lineend     = line + length - 1;
  eol         = 0;

  while (lineptr < lineend)
  {
   /*
    * Pre-load the buffer as needed...
    */

#ifdef WIN32
    WSASetLastError(0);
#else
    errno = 0;
#endif /* WIN32 */

    while (http->used == 0)
    {
     /*
      * No newline; see if there is more data to be read...
      */

      while (!_httpWait(http, http->wait_value, 1))
      {
        if (http->timeout_cb && (*http->timeout_cb)(http, http->timeout_data))
          continue;

        DEBUG_puts("3httpGets: Timed out!");
#ifdef WIN32
        http->error = WSAETIMEDOUT;
#else
        http->error = ETIMEDOUT;
#endif /* WIN32 */
        return (NULL);
      }

      bytes = http_read(http, http->buffer + http->used, (size_t)(HTTP_MAX_BUFFER - http->used));

      DEBUG_printf(("4httpGets: read " CUPS_LLFMT " bytes.", CUPS_LLCAST bytes));

      if (bytes < 0)
      {
       /*
        * Nope, can't get a line this time...
        */

#ifdef WIN32
        DEBUG_printf(("3httpGets: recv() error %d!", WSAGetLastError()));

        if (WSAGetLastError() == WSAEINTR)
          continue;
        else if (WSAGetLastError() == WSAEWOULDBLOCK)
        {
          if (http->timeout_cb && (*http->timeout_cb)(http, http->timeout_data))
            continue;

          http->error = WSAGetLastError();
        }
        else if (WSAGetLastError() != http->error)
        {
          http->error = WSAGetLastError();
          continue;
        }

#else
        DEBUG_printf(("3httpGets: recv() error %d!", errno));

        if (errno == EINTR)
          continue;
        else if (errno == EWOULDBLOCK || errno == EAGAIN)
        {
          if (http->timeout_cb && (*http->timeout_cb)(http, http->timeout_data))
            continue;
          else if (!http->timeout_cb && errno == EAGAIN)
            continue;

          http->error = errno;
        }
        else if (errno != http->error)
        {
          http->error = errno;
          continue;
        }
#endif /* WIN32 */

        return (NULL);
      }
      else if (bytes == 0)
      {
        http->error = EPIPE;

        return (NULL);
      }

     /*
      * Yup, update the amount used...
      */

      http->used += (int)bytes;
    }

   /*
    * Now copy as much of the current line as possible...
    */

    for (bufptr = http->buffer, bufend = http->buffer + http->used;
         lineptr < lineend && bufptr < bufend;)
    {
      if (*bufptr == 0x0a)
      {
        eol = 1;
        bufptr ++;
        break;
      }
      else if (*bufptr == 0x0d)
        bufptr ++;
      else
        *lineptr++ = *bufptr++;
    }

    http->used -= (int)(bufptr - http->buffer);
    if (http->used > 0)
      memmove(http->buffer, bufptr, (size_t)http->used);

    if (eol)
    {
     /*
      * End of line...
      */

      http->activity = time(NULL);

      *lineptr = '\0';

      DEBUG_printf(("3httpGets: Returning \"%s\"", line));

      return (line);
    }
  }

  DEBUG_puts("3httpGets: No new line available!");

  return (NULL);
}


/*
 * 'httpGetState()' - Get the current state of the HTTP request.
 */

http_state_t                            /* O - HTTP state */
httpGetState(http_t *http)              /* I - HTTP connection */
{
  return (http ? http->state : HTTP_STATE_ERROR);
}


/*
 * 'httpGetStatus()' - Get the status of the last HTTP request.
 *
 * @since CUPS 1.2/macOS 10.5@
 */

http_status_t                           /* O - HTTP status */
httpGetStatus(http_t *http)             /* I - HTTP connection */
{
  return (http ? http->status : HTTP_STATUS_ERROR);
}


/*
 * 'httpGetSubField()' - Get a sub-field value.
 *
 * @deprecated@ @exclude all@
 */

char *                                  /* O - Value or @code NULL@ */
httpGetSubField(http_t       *http,     /* I - HTTP connection */
                http_field_t field,     /* I - Field index */
                const char   *name,     /* I - Name of sub-field */
                char         *value)    /* O - Value string */
{
  return (httpGetSubField2(http, field, name, value, HTTP_MAX_VALUE));
}


/*
 * 'httpGetSubField2()' - Get a sub-field value.
 *
 * @since CUPS 1.2/macOS 10.5@
 */

char *                                  /* O - Value or @code NULL@ */
httpGetSubField2(http_t       *http,    /* I - HTTP connection */
                 http_field_t field,    /* I - Field index */
                 const char   *name,    /* I - Name of sub-field */
                 char         *value,   /* O - Value string */
                 int          valuelen) /* I - Size of value buffer */
{
  const char    *fptr;                  /* Pointer into field */
  char          temp[HTTP_MAX_VALUE],   /* Temporary buffer for name */
                *ptr,                   /* Pointer into string buffer */
                *end;                   /* End of value buffer */

  DEBUG_printf(("2httpGetSubField2(http=%p, field=%d, name=\"%s\", value=%p, valuelen=%d)", (void *)http, field, name, (void *)value, valuelen));

  if (!http || !name || !value || valuelen < 2 ||
      field <= HTTP_FIELD_UNKNOWN || field >= HTTP_FIELD_MAX)
    return (NULL);

  end = value + valuelen - 1;

  for (fptr = http->fields[field]; *fptr;)
  {
   /*
    * Skip leading whitespace...
    */

    while (_cups_isspace(*fptr))
      fptr ++;

    if (*fptr == ',')
    {
      fptr ++;
      continue;
    }

   /*
    * Get the sub-field name...
    */

    for (ptr = temp;
         *fptr && *fptr != '=' && !_cups_isspace(*fptr) &&
             ptr < (temp + sizeof(temp) - 1);
         *ptr++ = *fptr++);

    *ptr = '\0';

    DEBUG_printf(("4httpGetSubField2: name=\"%s\"", temp));

   /*
    * Skip trailing chars up to the '='...
    */

    while (_cups_isspace(*fptr))
      fptr ++;

    if (!*fptr)
      break;

    if (*fptr != '=')
      continue;

   /*
    * Skip = and leading whitespace...
    */

    fptr ++;

    while (_cups_isspace(*fptr))
      fptr ++;

    if (*fptr == '\"')
    {
     /*
      * Read quoted string...
      */

      for (ptr = value, fptr ++;
           *fptr && *fptr != '\"' && ptr < end;
           *ptr++ = *fptr++);

      *ptr = '\0';

      while (*fptr && *fptr != '\"')
        fptr ++;

      if (*fptr)
        fptr ++;
    }
    else
    {
     /*
      * Read unquoted string...
      */

      for (ptr = value;
           *fptr && !_cups_isspace(*fptr) && *fptr != ',' && ptr < end;
           *ptr++ = *fptr++);

      *ptr = '\0';

      while (*fptr && !_cups_isspace(*fptr) && *fptr != ',')
        fptr ++;
    }

    DEBUG_printf(("4httpGetSubField2: value=\"%s\"", value));

   /*
    * See if this is the one...
    */

    if (!strcmp(name, temp))
    {
      DEBUG_printf(("3httpGetSubField2: Returning \"%s\"", value));
      return (value);
    }
  }

  value[0] = '\0';

  DEBUG_puts("3httpGetSubField2: Returning NULL");

  return (NULL);
}


/*
 * 'httpGetVersion()' - Get the HTTP version at the other end.
 */

http_version_t                          /* O - Version number */
httpGetVersion(http_t *http)            /* I - HTTP connection */
{
  return (http ? http->version : HTTP_VERSION_1_0);
}


/*
 * 'httpHead()' - Send a HEAD request to the server.
 */

int                                     /* O - Status of call (0 = success) */
httpHead(http_t     *http,              /* I - HTTP connection */
         const char *uri)               /* I - URI for head */
{
  DEBUG_printf(("httpHead(http=%p, uri=\"%s\")", (void *)http, uri));
  return (http_send(http, HTTP_STATE_HEAD, uri));
}


/*
 * 'httpInitialize()' - Initialize the HTTP interface library and set the
 *                      default HTTP proxy (if any).
 */

void
httpInitialize(void)
{
  static int    initialized = 0;        /* Have we been called before? */
#ifdef WIN32
  WSADATA       winsockdata;            /* WinSock data */
#endif /* WIN32 */


  _cupsGlobalLock();
  if (initialized)
  {
    _cupsGlobalUnlock();
    return;
  }

#ifdef WIN32
  WSAStartup(MAKEWORD(2,2), &winsockdata);

#elif !defined(SO_NOSIGPIPE)
 /*
  * Ignore SIGPIPE signals...
  */

#  ifdef HAVE_SIGSET
  sigset(SIGPIPE, SIG_IGN);

#  elif defined(HAVE_SIGACTION)
  struct sigaction      action;         /* POSIX sigaction data */


  memset(&action, 0, sizeof(action));
  action.sa_handler = SIG_IGN;
  sigaction(SIGPIPE, &action, NULL);

#  else
  signal(SIGPIPE, SIG_IGN);
#  endif /* !SO_NOSIGPIPE */
#endif /* WIN32 */

#  ifdef HAVE_SSL
  _httpTLSInitialize();
#  endif /* HAVE_SSL */

  initialized = 1;
  _cupsGlobalUnlock();
}


/*
 * 'httpIsChunked()' - Report whether a message body is chunked.
 *
 * This function returns non-zero if the message body is composed of
 * variable-length chunks.
 *
 * @since CUPS 2.0/OS 10.10@
 */

int                                     /* O - 1 if chunked, 0 if not */
httpIsChunked(http_t *http)             /* I - HTTP connection */
{
  return (http ? http->data_encoding == HTTP_ENCODING_CHUNKED : 0);
}


/*
 * 'httpIsEncrypted()' - Report whether a connection is encrypted.
 *
 * This function returns non-zero if the connection is currently encrypted.
 *
 * @since CUPS 2.0/OS 10.10@
 */

int                                     /* O - 1 if encrypted, 0 if not */
httpIsEncrypted(http_t *http)           /* I - HTTP connection */
{
  return (http ? http->tls != NULL : 0);
}


/*
 * 'httpOptions()' - Send an OPTIONS request to the server.
 */

int                                     /* O - Status of call (0 = success) */
httpOptions(http_t     *http,           /* I - HTTP connection */
            const char *uri)            /* I - URI for options */
{
  return (http_send(http, HTTP_STATE_OPTIONS, uri));
}


/*
 * 'httpPeek()' - Peek at data from a HTTP connection.
 *
 * This function copies available data from the given HTTP connection, reading
 * a buffer as needed.  The data is still available for reading using
 * @link httpRead2@.
 *
 * For non-blocking connections the usual timeouts apply.
 *
 * @since CUPS 1.7/macOS 10.9@
 */

ssize_t                                 /* O - Number of bytes copied */
httpPeek(http_t *http,                  /* I - HTTP connection */
         char   *buffer,                /* I - Buffer for data */
         size_t length)                 /* I - Maximum number of bytes */
{
  ssize_t       bytes;                  /* Bytes read */
  char          len[32];                /* Length string */


  DEBUG_printf(("httpPeek(http=%p, buffer=%p, length=" CUPS_LLFMT ")", (void *)http, (void *)buffer, CUPS_LLCAST length));

  if (http == NULL || buffer == NULL)
    return (-1);

  http->activity = time(NULL);
  http->error    = 0;

  if (length <= 0)
    return (0);

  if (http->data_encoding == HTTP_ENCODING_CHUNKED &&
      http->data_remaining <= 0)
  {
    DEBUG_puts("2httpPeek: Getting chunk length...");

    if (httpGets(len, sizeof(len), http) == NULL)
    {
      DEBUG_puts("1httpPeek: Could not get length!");
      return (0);
    }

    if (!len[0])
    {
      DEBUG_puts("1httpPeek: Blank chunk length, trying again...");
      if (!httpGets(len, sizeof(len), http))
      {
        DEBUG_puts("1httpPeek: Could not get chunk length.");
        return (0);
      }
    }

    http->data_remaining = strtoll(len, NULL, 16);

    if (http->data_remaining < 0)
    {
      DEBUG_puts("1httpPeek: Negative chunk length!");
      return (0);
    }
  }

  DEBUG_printf(("2httpPeek: data_remaining=" CUPS_LLFMT,
                CUPS_LLCAST http->data_remaining));

  if (http->data_remaining <= 0 && http->data_encoding != HTTP_ENCODING_FIELDS)
  {
   /*
    * A zero-length chunk ends a transfer; unless we are reading POST
    * data, go idle...
    */

#ifdef HAVE_LIBZ
    if (http->coding >= _HTTP_CODING_GUNZIP)
      http_content_coding_finish(http);
#endif /* HAVE_LIBZ */

    if (http->data_encoding == HTTP_ENCODING_CHUNKED)
      httpGets(len, sizeof(len), http);

    if (http->state == HTTP_STATE_POST_RECV)
      http->state ++;
    else
      http->state = HTTP_STATE_STATUS;

    DEBUG_printf(("1httpPeek: 0-length chunk, set state to %s.",
                  httpStateString(http->state)));

   /*
    * Prevent future reads for this request...
    */

    http->data_encoding = HTTP_ENCODING_FIELDS;

    return (0);
  }
  else if (length > (size_t)http->data_remaining)
    length = (size_t)http->data_remaining;

#ifdef HAVE_LIBZ
  if (http->used == 0 &&
      (http->coding == _HTTP_CODING_IDENTITY ||
       (http->coding >= _HTTP_CODING_GUNZIP && http->stream.avail_in == 0)))
#else
  if (http->used == 0)
#endif /* HAVE_LIBZ */
  {
   /*
    * Buffer small reads for better performance...
    */

    ssize_t     buflen;                 /* Length of read for buffer */

    if (!http->blocking)
    {
      while (!httpWait(http, http->wait_value))
      {
        if (http->timeout_cb && (*http->timeout_cb)(http, http->timeout_data))
          continue;

        return (0);
      }
    }

    if ((size_t)http->data_remaining > sizeof(http->buffer))
      buflen = sizeof(http->buffer);
    else
      buflen = (ssize_t)http->data_remaining;

    DEBUG_printf(("2httpPeek: Reading %d bytes into buffer.", (int)buflen));
    bytes = http_read(http, http->buffer, (size_t)buflen);

    DEBUG_printf(("2httpPeek: Read " CUPS_LLFMT " bytes into buffer.",
                  CUPS_LLCAST bytes));
    if (bytes > 0)
    {
#ifdef DEBUG
      http_debug_hex("httpPeek", http->buffer, (int)bytes);
#endif /* DEBUG */

      http->used = (int)bytes;
    }
  }

#ifdef HAVE_LIBZ
  if (http->coding >= _HTTP_CODING_GUNZIP)
  {
#  ifdef HAVE_INFLATECOPY
    int         zerr;                   /* Decompressor error */
    z_stream    stream;                 /* Copy of decompressor stream */

    if (http->used > 0 && http->stream.avail_in < HTTP_MAX_BUFFER)
    {
      size_t buflen = buflen = HTTP_MAX_BUFFER - http->stream.avail_in;
                                        /* Number of bytes to copy */

      if (http->stream.avail_in > 0 &&
          http->stream.next_in > http->sbuffer)
        memmove(http->sbuffer, http->stream.next_in, http->stream.avail_in);

      http->stream.next_in = http->sbuffer;

      if (buflen > (size_t)http->data_remaining)
        buflen = (size_t)http->data_remaining;

      if (buflen > (size_t)http->used)
        buflen = (size_t)http->used;

      DEBUG_printf(("1httpPeek: Copying %d more bytes of data into "
                    "decompression buffer.", (int)buflen));

      memcpy(http->sbuffer + http->stream.avail_in, http->buffer, buflen);
      http->stream.avail_in += buflen;
      http->used            -= (int)buflen;
      http->data_remaining  -= (off_t)buflen;

      if (http->used > 0)
        memmove(http->buffer, http->buffer + buflen, (size_t)http->used);
    }

    DEBUG_printf(("2httpPeek: length=%d, avail_in=%d", (int)length,
                  (int)http->stream.avail_in));

    if (inflateCopy(&stream, &(http->stream)) != Z_OK)
    {
      DEBUG_puts("2httpPeek: Unable to copy decompressor stream.");
      http->error = ENOMEM;
      return (-1);
    }

    stream.next_out  = (Bytef *)buffer;
    stream.avail_out = (uInt)length;

    zerr = inflate(&stream, Z_SYNC_FLUSH);
    inflateEnd(&stream);

    if (zerr < Z_OK)
    {
      DEBUG_printf(("2httpPeek: zerr=%d", zerr));
#ifdef DEBUG
      http_debug_hex("2httpPeek", (char *)http->sbuffer, (int)http->stream.avail_in);
#endif /* DEBUG */

      http->error = EIO;
      return (-1);
    }

    bytes = (ssize_t)(length - http->stream.avail_out);

#  else
    DEBUG_puts("2httpPeek: No inflateCopy on this platform, httpPeek does not "
               "work with compressed streams.");
    return (-1);
#  endif /* HAVE_INFLATECOPY */
  }
  else
#endif /* HAVE_LIBZ */
  if (http->used > 0)
  {
    if (length > (size_t)http->used)
      length = (size_t)http->used;

    bytes = (ssize_t)length;

    DEBUG_printf(("2httpPeek: grabbing %d bytes from input buffer...",
                  (int)bytes));

    memcpy(buffer, http->buffer, length);
  }
  else
    bytes = 0;

  if (bytes < 0)
  {
#ifdef WIN32
    if (WSAGetLastError() == WSAEINTR || WSAGetLastError() == WSAEWOULDBLOCK)
      bytes = 0;
    else
      http->error = WSAGetLastError();
#else
    if (errno == EINTR || errno == EAGAIN)
      bytes = 0;
    else
      http->error = errno;
#endif /* WIN32 */
  }
  else if (bytes == 0)
  {
    http->error = EPIPE;
    return (0);
  }

  return (bytes);
}


/*
 * 'httpPost()' - Send a POST request to the server.
 */

int                                     /* O - Status of call (0 = success) */
httpPost(http_t     *http,              /* I - HTTP connection */
         const char *uri)               /* I - URI for post */
{
  return (http_send(http, HTTP_STATE_POST, uri));
}


/*
 * 'httpPrintf()' - Print a formatted string to a HTTP connection.
 *
 * @private@
 */

int                                     /* O - Number of bytes written */
httpPrintf(http_t     *http,            /* I - HTTP connection */
           const char *format,          /* I - printf-style format string */
           ...)                         /* I - Additional args as needed */
{
  ssize_t       bytes;                  /* Number of bytes to write */
  char          buf[16384];             /* Buffer for formatted string */
  va_list       ap;                     /* Variable argument pointer */


  DEBUG_printf(("2httpPrintf(http=%p, format=\"%s\", ...)", (void *)http, format));

  va_start(ap, format);
  bytes = vsnprintf(buf, sizeof(buf), format, ap);
  va_end(ap);

  DEBUG_printf(("3httpPrintf: (" CUPS_LLFMT " bytes) %s", CUPS_LLCAST bytes, buf));

  if (http->data_encoding == HTTP_ENCODING_FIELDS)
    return ((int)httpWrite2(http, buf, (size_t)bytes));
  else
  {
    if (http->wused)
    {
      DEBUG_puts("4httpPrintf: flushing existing data...");

      if (httpFlushWrite(http) < 0)
        return (-1);
    }

    return ((int)http_write(http, buf, (size_t)bytes));
  }
}


/*
 * 'httpPut()' - Send a PUT request to the server.
 */

int                                     /* O - Status of call (0 = success) */
httpPut(http_t     *http,               /* I - HTTP connection */
        const char *uri)                /* I - URI to put */
{
  DEBUG_printf(("httpPut(http=%p, uri=\"%s\")", (void *)http, uri));
  return (http_send(http, HTTP_STATE_PUT, uri));
}


/*
 * 'httpRead()' - Read data from a HTTP connection.
 *
 * This function is deprecated. Use the httpRead2() function which can
 * read more than 2GB of data.
 *
 * @deprecated@ @exclude all@
 */

int                                     /* O - Number of bytes read */
httpRead(http_t *http,                  /* I - HTTP connection */
         char   *buffer,                /* I - Buffer for data */
         int    length)                 /* I - Maximum number of bytes */
{
  return ((int)httpRead2(http, buffer, (size_t)length));
}


/*
 * 'httpRead2()' - Read data from a HTTP connection.
 *
 * @since CUPS 1.2/macOS 10.5@
 */

ssize_t                                 /* O - Number of bytes read */
httpRead2(http_t *http,                 /* I - HTTP connection */
          char   *buffer,               /* I - Buffer for data */
          size_t length)                /* I - Maximum number of bytes */
{
  ssize_t       bytes;                  /* Bytes read */


#ifdef HAVE_LIBZ
  DEBUG_printf(("httpRead2(http=%p, buffer=%p, length=" CUPS_LLFMT ") coding=%d data_encoding=%d data_remaining=" CUPS_LLFMT, (void *)http, (void *)buffer, CUPS_LLCAST length, http->coding, http->data_encoding, CUPS_LLCAST http->data_remaining));
#else
  DEBUG_printf(("httpRead2(http=%p, buffer=%p, length=" CUPS_LLFMT ") data_encoding=%d data_remaining=" CUPS_LLFMT, (void *)http, (void *)buffer, CUPS_LLCAST length, http->data_encoding, CUPS_LLCAST http->data_remaining));
#endif /* HAVE_LIBZ */

  if (http == NULL || buffer == NULL)
    return (-1);

  http->activity = time(NULL);
  http->error    = 0;

  if (length <= 0)
    return (0);

#ifdef HAVE_LIBZ
  if (http->coding >= _HTTP_CODING_GUNZIP)
  {
    do
    {
      if (http->stream.avail_in > 0)
      {
        int     zerr;                   /* Decompressor error */

        DEBUG_printf(("2httpRead2: avail_in=%d, avail_out=%d",
                      (int)http->stream.avail_in, (int)length));

        http->stream.next_out  = (Bytef *)buffer;
        http->stream.avail_out = (uInt)length;

        if ((zerr = inflate(&(http->stream), Z_SYNC_FLUSH)) < Z_OK)
        {
          DEBUG_printf(("2httpRead2: zerr=%d", zerr));
#ifdef DEBUG
          http_debug_hex("2httpRead2", (char *)http->sbuffer, (int)http->stream.avail_in);
#endif /* DEBUG */

          http->error = EIO;
          return (-1);
        }

        bytes = (ssize_t)(length - http->stream.avail_out);

        DEBUG_printf(("2httpRead2: avail_in=%d, avail_out=%d, bytes=%d",
                      http->stream.avail_in, http->stream.avail_out,
                      (int)bytes));
      }
      else
        bytes = 0;

      if (bytes == 0)
      {
        ssize_t buflen = HTTP_MAX_BUFFER - (ssize_t)http->stream.avail_in;
                                        /* Additional bytes for buffer */

        if (buflen > 0)
        {
          if (http->stream.avail_in > 0 &&
              http->stream.next_in > http->sbuffer)
            memmove(http->sbuffer, http->stream.next_in, http->stream.avail_in);

          http->stream.next_in = http->sbuffer;

          DEBUG_printf(("1httpRead2: Reading up to %d more bytes of data into "
                        "decompression buffer.", (int)buflen));

          if (http->data_remaining > 0)
          {
            if (buflen > http->data_remaining)
              buflen = (ssize_t)http->data_remaining;

            bytes = http_read_buffered(http, (char *)http->sbuffer + http->stream.avail_in, (size_t)buflen);
          }
          else if (http->data_encoding == HTTP_ENCODING_CHUNKED)
            bytes = http_read_chunk(http, (char *)http->sbuffer + http->stream.avail_in, (size_t)buflen);
          else
            bytes = 0;

          if (bytes < 0)
            return (bytes);
          else if (bytes == 0)
            break;

          DEBUG_printf(("1httpRead2: Adding " CUPS_LLFMT " bytes to "
                        "decompression buffer.", CUPS_LLCAST bytes));

          http->data_remaining  -= bytes;
          http->stream.avail_in += (uInt)bytes;

          if (http->data_remaining <= 0 &&
              http->data_encoding == HTTP_ENCODING_CHUNKED)
          {
           /*
            * Read the trailing blank line now...
            */

            char        len[32];                /* Length string */

            httpGets(len, sizeof(len), http);
          }

          bytes = 0;
        }
        else
          return (0);
      }
    }
    while (bytes == 0);
  }
  else
#endif /* HAVE_LIBZ */
  if (http->data_remaining == 0 && http->data_encoding == HTTP_ENCODING_CHUNKED)
  {
    if ((bytes = http_read_chunk(http, buffer, length)) > 0)
    {
      http->data_remaining -= bytes;

      if (http->data_remaining <= 0)
      {
       /*
        * Read the trailing blank line now...
        */

        char    len[32];                /* Length string */

        httpGets(len, sizeof(len), http);
      }
    }
  }
  else if (http->data_remaining <= 0)
  {
   /*
    * No more data to read...
    */

    return (0);
  }
  else
  {
    DEBUG_printf(("1httpRead2: Reading up to %d bytes into buffer.",
                  (int)length));

    if (length > (size_t)http->data_remaining)
      length = (size_t)http->data_remaining;

    if ((bytes = http_read_buffered(http, buffer, length)) > 0)
    {
      http->data_remaining -= bytes;

      if (http->data_remaining <= 0 &&
          http->data_encoding == HTTP_ENCODING_CHUNKED)
      {
       /*
        * Read the trailing blank line now...
        */

        char    len[32];                /* Length string */

        httpGets(len, sizeof(len), http);
      }
    }
  }

  if (
#ifdef HAVE_LIBZ
      (http->coding == _HTTP_CODING_IDENTITY ||
       (http->coding >= _HTTP_CODING_GUNZIP && http->stream.avail_in == 0)) &&
#endif /* HAVE_LIBZ */
      ((http->data_remaining <= 0 &&
        http->data_encoding == HTTP_ENCODING_LENGTH) ||
       (http->data_encoding == HTTP_ENCODING_CHUNKED && bytes == 0)))
  {
#ifdef HAVE_LIBZ
    if (http->coding >= _HTTP_CODING_GUNZIP)
      http_content_coding_finish(http);
#endif /* HAVE_LIBZ */

    if (http->state == HTTP_STATE_POST_RECV)
      http->state ++;
    else if (http->state == HTTP_STATE_GET_SEND ||
             http->state == HTTP_STATE_POST_SEND)
      http->state = HTTP_STATE_WAITING;
    else
      http->state = HTTP_STATE_STATUS;

    DEBUG_printf(("1httpRead2: End of content, set state to %s.",
                  httpStateString(http->state)));
  }

  return (bytes);
}


/*
 * 'httpReadRequest()' - Read a HTTP request from a connection.
 *
 * @since CUPS 1.7/macOS 10.9@
 */

http_state_t                            /* O - New state of connection */
httpReadRequest(http_t *http,           /* I - HTTP connection */
                char   *uri,            /* I - URI buffer */
                size_t urilen)          /* I - Size of URI buffer */
{
  char  line[4096],                     /* HTTP request line */
        *req_method,                    /* HTTP request method */
        *req_uri,                       /* HTTP request URI */
        *req_version;                   /* HTTP request version number string */


 /*
  * Range check input...
  */

  DEBUG_printf(("httpReadRequest(http=%p, uri=%p, urilen=" CUPS_LLFMT ")", (void *)http, (void *)uri, CUPS_LLCAST urilen));

  if (uri)
    *uri = '\0';

  if (!http || !uri || urilen < 1)
  {
    DEBUG_puts("1httpReadRequest: Bad arguments, returning HTTP_STATE_ERROR.");
    return (HTTP_STATE_ERROR);
  }
  else if (http->state != HTTP_STATE_WAITING)
  {
    DEBUG_printf(("1httpReadRequest: Bad state %s, returning HTTP_STATE_ERROR.",
                  httpStateString(http->state)));
    return (HTTP_STATE_ERROR);
  }

 /*
  * Reset state...
  */

  httpClearFields(http);

  http->activity       = time(NULL);
  http->data_encoding  = HTTP_ENCODING_FIELDS;
  http->data_remaining = 0;
  http->keep_alive     = HTTP_KEEPALIVE_OFF;
  http->status         = HTTP_STATUS_OK;
  http->version        = HTTP_VERSION_1_1;

 /*
  * Read a line from the socket...
  */

  if (!httpGets(line, sizeof(line), http))
  {
    DEBUG_puts("1httpReadRequest: Unable to read, returning HTTP_STATE_ERROR");
    return (HTTP_STATE_ERROR);
  }

  if (!line[0])
  {
    DEBUG_puts("1httpReadRequest: Blank line, returning HTTP_STATE_WAITING");
    return (HTTP_STATE_WAITING);
  }

  DEBUG_printf(("1httpReadRequest: %s", line));

 /*
  * Parse it...
  */

  req_method = line;
  req_uri    = line;

  while (*req_uri && !isspace(*req_uri & 255))
    req_uri ++;

  if (!*req_uri)
  {
    DEBUG_puts("1httpReadRequest: No request URI.");
    _cupsSetError(IPP_STATUS_ERROR_INTERNAL, _("No request URI."), 1);
    return (HTTP_STATE_ERROR);
  }

  *req_uri++ = '\0';

  while (*req_uri && isspace(*req_uri & 255))
    req_uri ++;

  req_version = req_uri;

  while (*req_version && !isspace(*req_version & 255))
    req_version ++;

  if (!*req_version)
  {
    DEBUG_puts("1httpReadRequest: No request protocol version.");
    _cupsSetError(IPP_STATUS_ERROR_INTERNAL, _("No request protocol version."), 1);
    return (HTTP_STATE_ERROR);
  }

  *req_version++ = '\0';

  while (*req_version && isspace(*req_version & 255))
    req_version ++;

 /*
  * Validate...
  */

  if (!strcmp(req_method, "OPTIONS"))
    http->state = HTTP_STATE_OPTIONS;
  else if (!strcmp(req_method, "GET"))
    http->state = HTTP_STATE_GET;
  else if (!strcmp(req_method, "HEAD"))
    http->state = HTTP_STATE_HEAD;
  else if (!strcmp(req_method, "POST"))
    http->state = HTTP_STATE_POST;
  else if (!strcmp(req_method, "PUT"))
    http->state = HTTP_STATE_PUT;
  else if (!strcmp(req_method, "DELETE"))
    http->state = HTTP_STATE_DELETE;
  else if (!strcmp(req_method, "TRACE"))
    http->state = HTTP_STATE_TRACE;
  else if (!strcmp(req_method, "CONNECT"))
    http->state = HTTP_STATE_CONNECT;
  else
  {
    DEBUG_printf(("1httpReadRequest: Unknown method \"%s\".", req_method));
    _cupsSetError(IPP_STATUS_ERROR_INTERNAL, _("Unknown request method."), 1);
    return (HTTP_STATE_UNKNOWN_METHOD);
  }

  DEBUG_printf(("1httpReadRequest: Set state to %s.",
                httpStateString(http->state)));

  if (!strcmp(req_version, "HTTP/1.0"))
  {
    http->version    = HTTP_VERSION_1_0;
    http->keep_alive = HTTP_KEEPALIVE_OFF;
  }
  else if (!strcmp(req_version, "HTTP/1.1"))
  {
    http->version    = HTTP_VERSION_1_1;
    http->keep_alive = HTTP_KEEPALIVE_ON;
  }
  else
  {
    DEBUG_printf(("1httpReadRequest: Unknown version \"%s\".", req_version));
    _cupsSetError(IPP_STATUS_ERROR_INTERNAL, _("Unknown request version."), 1);
    return (HTTP_STATE_UNKNOWN_VERSION);
  }

  DEBUG_printf(("1httpReadRequest: URI is \"%s\".", req_uri));
  strlcpy(uri, req_uri, urilen);

  return (http->state);
}


/*
 * 'httpReconnect()' - Reconnect to a HTTP server.
 *
 * This function is deprecated. Please use the @link httpReconnect2@ function
 * instead.
 *
 * @deprecated@ @exclude all@
 */

int                                     /* O - 0 on success, non-zero on failure */
httpReconnect(http_t *http)             /* I - HTTP connection */
{
  DEBUG_printf(("httpReconnect(http=%p)", (void *)http));

  return (httpReconnect2(http, 30000, NULL));
}


/*
 * 'httpReconnect2()' - Reconnect to a HTTP server with timeout and optional
 *                      cancel.
 */

int                                     /* O - 0 on success, non-zero on failure */
httpReconnect2(http_t *http,            /* I - HTTP connection */
               int    msec,             /* I - Timeout in milliseconds */
               int    *cancel)          /* I - Pointer to "cancel" variable */
{
  http_addrlist_t       *addr;          /* Connected address */
#ifdef DEBUG
  http_addrlist_t       *current;       /* Current address */
  char                  temp[256];      /* Temporary address string */
#endif /* DEBUG */


  DEBUG_printf(("httpReconnect2(http=%p, msec=%d, cancel=%p)", (void *)http, msec, (void *)cancel));

  if (!http)
  {
    _cupsSetError(IPP_STATUS_ERROR_INTERNAL, strerror(EINVAL), 0);
    return (-1);
  }

#ifdef HAVE_SSL
  if (http->tls)
  {
    DEBUG_puts("2httpReconnect2: Shutting down SSL/TLS...");
    _httpTLSStop(http);
  }
#endif /* HAVE_SSL */

 /*
  * Close any previously open socket...
  */

  if (http->fd >= 0)
  {
    DEBUG_printf(("2httpReconnect2: Closing socket %d...", http->fd));

    httpAddrClose(NULL, http->fd);

    http->fd = -1;
  }

 /*
  * Reset all state (except fields, which may be reused)...
  */

  http->state           = HTTP_STATE_WAITING;
  http->version         = HTTP_VERSION_1_1;
  http->keep_alive      = HTTP_KEEPALIVE_OFF;
  memset(&http->_hostaddr, 0, sizeof(http->_hostaddr));
  http->data_encoding   = HTTP_ENCODING_FIELDS;
  http->_data_remaining = 0;
  http->used            = 0;
  http->data_remaining  = 0;
  http->hostaddr        = NULL;
  http->wused           = 0;

 /*
  * Connect to the server...
  */

#ifdef DEBUG
  for (current = http->addrlist; current; current = current->next)
    DEBUG_printf(("2httpReconnect2: Address %s:%d",
                  httpAddrString(&(current->addr), temp, sizeof(temp)),
                  httpAddrPort(&(current->addr))));
#endif /* DEBUG */

  if ((addr = httpAddrConnect2(http->addrlist, &(http->fd), msec, cancel)) == NULL)
  {
   /*
    * Unable to connect...
    */

#ifdef WIN32
    http->error  = WSAGetLastError();
#else
    http->error  = errno;
#endif /* WIN32 */
    http->status = HTTP_STATUS_ERROR;

    DEBUG_printf(("1httpReconnect2: httpAddrConnect failed: %s",
                  strerror(http->error)));

    return (-1);
  }

  DEBUG_printf(("2httpReconnect2: New socket=%d", http->fd));

  if (http->timeout_value > 0)
    http_set_timeout(http->fd, http->timeout_value);

  http->hostaddr = &(addr->addr);
  http->error    = 0;

#ifdef HAVE_SSL
  if (http->encryption == HTTP_ENCRYPTION_ALWAYS)
  {
   /*
    * Always do encryption via SSL.
    */

    if (_httpTLSStart(http) != 0)
    {
      httpAddrClose(NULL, http->fd);

      return (-1);
    }
  }
  else if (http->encryption == HTTP_ENCRYPTION_REQUIRED && !http->tls_upgrade)
    return (http_tls_upgrade(http));
#endif /* HAVE_SSL */

  DEBUG_printf(("1httpReconnect2: Connected to %s:%d...",
                httpAddrString(http->hostaddr, temp, sizeof(temp)),
                httpAddrPort(http->hostaddr)));

  return (0);
}


/*
 * 'httpSetAuthString()' - Set the current authorization string.
 *
 * This function just stores a copy of the current authorization string in
 * the HTTP connection object.  You must still call @link httpSetField@ to set
 * @code HTTP_FIELD_AUTHORIZATION@ prior to issuing a HTTP request using
 * @link httpGet@, @link httpHead@, @link httpOptions@, @link httpPost@, or
 * @link httpPut@.
 *
 * @since CUPS 1.3/macOS 10.5@
 */

void
httpSetAuthString(http_t     *http,     /* I - HTTP connection */
                  const char *scheme,   /* I - Auth scheme (NULL to clear it) */
                  const char *data)     /* I - Auth data (NULL for none) */
{
 /*
  * Range check input...
  */

  if (!http)
    return;

  if (http->authstring && http->authstring != http->_authstring)
    free(http->authstring);

  http->authstring = http->_authstring;

  if (scheme)
  {
   /*
    * Set the current authorization string...
    */

    size_t len = strlen(scheme) + (data ? strlen(data) + 1 : 0) + 1;
    char *temp;

    if (len > sizeof(http->_authstring))
    {
      if ((temp = malloc(len)) == NULL)
        len = sizeof(http->_authstring);
      else
        http->authstring = temp;
    }

    if (data)
      snprintf(http->authstring, len, "%s %s", scheme, data);
    else
      strlcpy(http->authstring, scheme, len);
  }
  else
  {
   /*
    * Clear the current authorization string...
    */

    http->_authstring[0] = '\0';
  }
}


/*
 * 'httpSetCredentials()' - Set the credentials associated with an encrypted
 *                          connection.
 *
 * @since CUPS 1.5/macOS 10.7@
 */

int                                             /* O - Status of call (0 = success) */
httpSetCredentials(http_t       *http,          /* I - HTTP connection */
                   cups_array_t *credentials)   /* I - Array of credentials */
{
  if (!http || cupsArrayCount(credentials) < 1)
    return (-1);

#ifdef HAVE_SSL
  _httpFreeCredentials(http->tls_credentials);

  http->tls_credentials = _httpCreateCredentials(credentials);
#endif /* HAVE_SSL */

  return (http->tls_credentials ? 0 : -1);
}


/*
 * 'httpSetCookie()' - Set the cookie value(s).
 *
 * @since CUPS 1.1.19/macOS 10.3@
 */

void
httpSetCookie(http_t     *http,         /* I - Connection */
              const char *cookie)       /* I - Cookie string */
{
  if (!http)
    return;

  if (http->cookie)
    free(http->cookie);

  if (cookie)
    http->cookie = strdup(cookie);
  else
    http->cookie = NULL;
}


/*
 * 'httpSetDefaultField()' - Set the default value of an HTTP header.
 *
 * Currently only @code HTTP_FIELD_ACCEPT_ENCODING@, @code HTTP_FIELD_SERVER@,
 * and @code HTTP_FIELD_USER_AGENT@ can be set.
 *
 * @since CUPS 1.7/macOS 10.9@
 */

void
httpSetDefaultField(http_t       *http, /* I - HTTP connection */
                    http_field_t field, /* I - Field index */
                    const char   *value)/* I - Value */
{
  DEBUG_printf(("httpSetDefaultField(http=%p, field=%d(%s), value=\"%s\")", (void *)http, field, http_fields[field], value));

  if (!http || field <= HTTP_FIELD_UNKNOWN || field >= HTTP_FIELD_MAX)
    return;

  if (http->default_fields[field])
    free(http->default_fields[field]);

  http->default_fields[field] = value ? strdup(value) : NULL;
}


/*
 * 'httpSetExpect()' - Set the Expect: header in a request.
 *
 * Currently only @code HTTP_STATUS_CONTINUE@ is supported for the "expect"
 * argument.
 *
 * @since CUPS 1.2/macOS 10.5@
 */

void
httpSetExpect(http_t        *http,      /* I - HTTP connection */
              http_status_t expect)     /* I - HTTP status to expect
                                               (@code HTTP_STATUS_CONTINUE@) */
{
  DEBUG_printf(("httpSetExpect(http=%p, expect=%d)", (void *)http, expect));

  if (http)
    http->expect = expect;
}


/*
 * 'httpSetField()' - Set the value of an HTTP header.
 */

void
httpSetField(http_t       *http,        /* I - HTTP connection */
             http_field_t field,        /* I - Field index */
             const char   *value)       /* I - Value */
{
  DEBUG_printf(("httpSetField(http=%p, field=%d(%s), value=\"%s\")", (void *)http, field, http_fields[field], value));

  if (!http || field <= HTTP_FIELD_UNKNOWN || field >= HTTP_FIELD_MAX || !value)
    return;

  http_add_field(http, field, value, 0);
}


/*
 * 'httpSetKeepAlive()' - Set the current Keep-Alive state of a connection.
 *
 * @since CUPS 2.0/OS 10.10@
 */

void
httpSetKeepAlive(
    http_t           *http,             /* I - HTTP connection */
    http_keepalive_t keep_alive)        /* I - New Keep-Alive value */
{
  if (http)
    http->keep_alive = keep_alive;
}


/*
 * 'httpSetLength()' - Set the content-length and content-encoding.
 *
 * @since CUPS 1.2/macOS 10.5@
 */

void
httpSetLength(http_t *http,             /* I - HTTP connection */
              size_t length)            /* I - Length (0 for chunked) */
{
  DEBUG_printf(("httpSetLength(http=%p, length=" CUPS_LLFMT ")", (void *)http, CUPS_LLCAST length));

  if (!http)
    return;

  if (!length)
  {
    httpSetField(http, HTTP_FIELD_TRANSFER_ENCODING, "chunked");
    httpSetField(http, HTTP_FIELD_CONTENT_LENGTH, "");
  }
  else
  {
    char len[32];                       /* Length string */


    snprintf(len, sizeof(len), CUPS_LLFMT, CUPS_LLCAST length);
    httpSetField(http, HTTP_FIELD_TRANSFER_ENCODING, "");
    httpSetField(http, HTTP_FIELD_CONTENT_LENGTH, len);
  }
}


/*
 * 'httpSetTimeout()' - Set read/write timeouts and an optional callback.
 *
 * The optional timeout callback receives both the HTTP connection and a user
 * data pointer and must return 1 to continue or 0 to error (time) out.
 *
 * @since CUPS 1.5/macOS 10.7@
 */

void
httpSetTimeout(
    http_t            *http,            /* I - HTTP connection */
    double            timeout,          /* I - Number of seconds for timeout,
                                               must be greater than 0 */
    http_timeout_cb_t cb,               /* I - Callback function or @code NULL@ */
    void              *user_data)       /* I - User data pointer */
{
  if (!http || timeout <= 0.0)
    return;

  http->timeout_cb    = cb;
  http->timeout_data  = user_data;
  http->timeout_value = timeout;

  if (http->fd >= 0)
    http_set_timeout(http->fd, timeout);

  http_set_wait(http);
}


/*
 * 'httpShutdown()' - Shutdown one side of an HTTP connection.
 *
 * @since CUPS 2.0/OS 10.10@
 */

void
httpShutdown(http_t *http)              /* I - HTTP connection */
{
  if (!http || http->fd < 0)
    return;

#ifdef HAVE_SSL
  if (http->tls)
    _httpTLSStop(http);
#endif /* HAVE_SSL */

#ifdef WIN32
  shutdown(http->fd, SD_RECEIVE);       /* Microsoft-ism... */
#else
  shutdown(http->fd, SHUT_RD);
#endif /* WIN32 */
}


/*
 * 'httpTrace()' - Send an TRACE request to the server.
 *
 * @exclude all@
 */

int                                     /* O - Status of call (0 = success) */
httpTrace(http_t     *http,             /* I - HTTP connection */
          const char *uri)              /* I - URI for trace */
{
  return (http_send(http, HTTP_STATE_TRACE, uri));
}


/*
 * '_httpUpdate()' - Update the current HTTP status for incoming data.
 *
 * Note: Unlike httpUpdate(), this function does not flush pending write data
 * and only retrieves a single status line from the HTTP connection.
 */

int                                     /* O - 1 to continue, 0 to stop */
_httpUpdate(http_t        *http,        /* I - HTTP connection */
            http_status_t *status)      /* O - Current HTTP status */
{
  char          line[32768],            /* Line from connection... */
                *value;                 /* Pointer to value on line */
  http_field_t  field;                  /* Field index */
  int           major, minor;           /* HTTP version numbers */


  DEBUG_printf(("_httpUpdate(http=%p, status=%p), state=%s", (void *)http, (void *)status, httpStateString(http->state)));

 /*
  * Grab a single line from the connection...
  */

  if (!httpGets(line, sizeof(line), http))
  {
    *status = HTTP_STATUS_ERROR;
    return (0);
  }

  DEBUG_printf(("2_httpUpdate: Got \"%s\"", line));

  if (line[0] == '\0')
  {
   /*
    * Blank line means the start of the data section (if any).  Return
    * the result code, too...
    *
    * If we get status 100 (HTTP_STATUS_CONTINUE), then we *don't* change
    * states.  Instead, we just return HTTP_STATUS_CONTINUE to the caller and
    * keep on tryin'...
    */

    if (http->status == HTTP_STATUS_CONTINUE)
    {
      *status = http->status;
      return (0);
    }

    if (http->status < HTTP_STATUS_BAD_REQUEST)
      http->digest_tries = 0;

#ifdef HAVE_SSL
    if (http->status == HTTP_STATUS_SWITCHING_PROTOCOLS && !http->tls)
    {
      if (_httpTLSStart(http) != 0)
      {
        httpAddrClose(NULL, http->fd);

        *status = http->status = HTTP_STATUS_ERROR;
        return (0);
      }

      *status = HTTP_STATUS_CONTINUE;
      return (0);
    }
#endif /* HAVE_SSL */

    if (http_set_length(http) < 0)
    {
      DEBUG_puts("1_httpUpdate: Bad Content-Length.");
      http->error  = EINVAL;
      http->status = *status = HTTP_STATUS_ERROR;
      return (0);
    }

    switch (http->state)
    {
      case HTTP_STATE_GET :
      case HTTP_STATE_POST :
      case HTTP_STATE_POST_RECV :
      case HTTP_STATE_PUT :
          http->state ++;

          DEBUG_printf(("1_httpUpdate: Set state to %s.",
                        httpStateString(http->state)));

      case HTTP_STATE_POST_SEND :
      case HTTP_STATE_HEAD :
          break;

      default :
          http->state = HTTP_STATE_WAITING;

          DEBUG_puts("1_httpUpdate: Reset state to HTTP_STATE_WAITING.");
          break;
    }

#ifdef HAVE_LIBZ
    DEBUG_puts("1_httpUpdate: Calling http_content_coding_start.");
    http_content_coding_start(http,
                              httpGetField(http, HTTP_FIELD_CONTENT_ENCODING));
#endif /* HAVE_LIBZ */

    *status = http->status;
    return (0);
  }
  else if (!strncmp(line, "HTTP/", 5) && http->mode == _HTTP_MODE_CLIENT)
  {
   /*
    * Got the beginning of a response...
    */

    int intstatus;                      /* Status value as an integer */

    if (sscanf(line, "HTTP/%d.%d%d", &major, &minor, &intstatus) != 3)
    {
      *status = http->status = HTTP_STATUS_ERROR;
      return (0);
    }

    httpClearFields(http);

    http->version = (http_version_t)(major * 100 + minor);
    *status       = http->status = (http_status_t)intstatus;
  }
  else if ((value = strchr(line, ':')) != NULL)
  {
   /*
    * Got a value...
    */

    *value++ = '\0';
    while (_cups_isspace(*value))
      value ++;

    DEBUG_printf(("1_httpUpdate: Header %s: %s", line, value));

   /*
    * Be tolerants of servers that send unknown attribute fields...
    */

    if (!_cups_strcasecmp(line, "expect"))
    {
     /*
      * "Expect: 100-continue" or similar...
      */

      http->expect = (http_status_t)atoi(value);
    }
    else if (!_cups_strcasecmp(line, "cookie"))
    {
     /*
      * "Cookie: name=value[; name=value ...]" - replaces previous cookies...
      */

      httpSetCookie(http, value);
    }
    else if ((field = httpFieldValue(line)) != HTTP_FIELD_UNKNOWN)
    {
      http_add_field(http, field, value, 1);

      if (field == HTTP_FIELD_AUTHENTICATION_INFO)
        httpGetSubField2(http, HTTP_FIELD_AUTHENTICATION_INFO, "nextnonce", http->nextnonce, (int)sizeof(http->nextnonce));
    }
#ifdef DEBUG
    else
      DEBUG_printf(("1_httpUpdate: unknown field %s seen!", line));
#endif /* DEBUG */
  }
  else
  {
    DEBUG_printf(("1_httpUpdate: Bad response line \"%s\"!", line));
    http->error  = EINVAL;
    http->status = *status = HTTP_STATUS_ERROR;
    return (0);
  }

  return (1);
}


/*
 * 'httpUpdate()' - Update the current HTTP state for incoming data.
 */

http_status_t                           /* O - HTTP status */
httpUpdate(http_t *http)                /* I - HTTP connection */
{
  http_status_t status;                 /* Request status */


  DEBUG_printf(("httpUpdate(http=%p), state=%s", (void *)http, httpStateString(http->state)));

 /*
  * Flush pending data, if any...
  */

  if (http->wused)
  {
    DEBUG_puts("2httpUpdate: flushing buffer...");

    if (httpFlushWrite(http) < 0)
      return (HTTP_STATUS_ERROR);
  }

 /*
  * If we haven't issued any commands, then there is nothing to "update"...
  */

  if (http->state == HTTP_STATE_WAITING)
    return (HTTP_STATUS_CONTINUE);

 /*
  * Grab all of the lines we can from the connection...
  */

  while (_httpUpdate(http, &status));

 /*
  * See if there was an error...
  */

  if (http->error == EPIPE && http->status > HTTP_STATUS_CONTINUE)
  {
    DEBUG_printf(("1httpUpdate: Returning status %d...", http->status));
    return (http->status);
  }

  if (http->error)
  {
    DEBUG_printf(("1httpUpdate: socket error %d - %s", http->error,
                  strerror(http->error)));
    http->status = HTTP_STATUS_ERROR;
    return (HTTP_STATUS_ERROR);
  }

 /*
  * Return the current status...
  */

  return (status);
}


/*
 * '_httpWait()' - Wait for data available on a connection (no flush).
 */

int                                     /* O - 1 if data is available, 0 otherwise */
_httpWait(http_t *http,                 /* I - HTTP connection */
          int    msec,                  /* I - Milliseconds to wait */
          int    usessl)                /* I - Use SSL context? */
{
#ifdef HAVE_POLL
  struct pollfd         pfd;            /* Polled file descriptor */
#else
  fd_set                input_set;      /* select() input set */
  struct timeval        timeout;        /* Timeout */
#endif /* HAVE_POLL */
  int                   nfds;           /* Result from select()/poll() */


  DEBUG_printf(("4_httpWait(http=%p, msec=%d, usessl=%d)", (void *)http, msec, usessl));

  if (http->fd < 0)
  {
    DEBUG_printf(("5_httpWait: Returning 0 since fd=%d", http->fd));
    return (0);
  }

 /*
  * Check the SSL/TLS buffers for data first...
  */

#ifdef HAVE_SSL
  if (http->tls && _httpTLSPending(http))
  {
    DEBUG_puts("5_httpWait: Return 1 since there is pending TLS data.");
    return (1);
  }
#endif /* HAVE_SSL */

 /*
  * Then try doing a select() or poll() to poll the socket...
  */

#ifdef HAVE_POLL
  pfd.fd     = http->fd;
  pfd.events = POLLIN;

  do
  {
    nfds = poll(&pfd, 1, msec);
  }
  while (nfds < 0 && (errno == EINTR || errno == EAGAIN));

#else
  do
  {
    FD_ZERO(&input_set);
    FD_SET(http->fd, &input_set);

    DEBUG_printf(("6_httpWait: msec=%d, http->fd=%d", msec, http->fd));

    if (msec >= 0)
    {
      timeout.tv_sec  = msec / 1000;
      timeout.tv_usec = (msec % 1000) * 1000;

      nfds = select(http->fd + 1, &input_set, NULL, NULL, &timeout);
    }
    else
      nfds = select(http->fd + 1, &input_set, NULL, NULL, NULL);

    DEBUG_printf(("6_httpWait: select() returned %d...", nfds));
  }
#  ifdef WIN32
  while (nfds < 0 && (WSAGetLastError() == WSAEINTR ||
                      WSAGetLastError() == WSAEWOULDBLOCK));
#  else
  while (nfds < 0 && (errno == EINTR || errno == EAGAIN));
#  endif /* WIN32 */
#endif /* HAVE_POLL */

  DEBUG_printf(("5_httpWait: returning with nfds=%d, errno=%d...", nfds,
                errno));

  return (nfds > 0);
}


/*
 * 'httpWait()' - Wait for data available on a connection.
 *
 * @since CUPS 1.1.19/macOS 10.3@
 */

int                                     /* O - 1 if data is available, 0 otherwise */
httpWait(http_t *http,                  /* I - HTTP connection */
         int    msec)                   /* I - Milliseconds to wait */
{
 /*
  * First see if there is data in the buffer...
  */

  DEBUG_printf(("2httpWait(http=%p, msec=%d)", (void *)http, msec));

  if (http == NULL)
    return (0);

  if (http->used)
  {
    DEBUG_puts("3httpWait: Returning 1 since there is buffered data ready.");
    return (1);
  }

#ifdef HAVE_LIBZ
  if (http->coding >= _HTTP_CODING_GUNZIP && http->stream.avail_in > 0)
  {
    DEBUG_puts("3httpWait: Returning 1 since there is buffered data ready.");
    return (1);
  }
#endif /* HAVE_LIBZ */

 /*
  * Flush pending data, if any...
  */

  if (http->wused)
  {
    DEBUG_puts("3httpWait: Flushing write buffer.");

    if (httpFlushWrite(http) < 0)
      return (0);
  }

 /*
  * If not, check the SSL/TLS buffers and do a select() on the connection...
  */

  return (_httpWait(http, msec, 1));
}


/*
 * 'httpWrite()' - Write data to a HTTP connection.
 *
 * This function is deprecated. Use the httpWrite2() function which can
 * write more than 2GB of data.
 *
 * @deprecated@ @exclude all@
 */

int                                     /* O - Number of bytes written */
httpWrite(http_t     *http,             /* I - HTTP connection */
          const char *buffer,           /* I - Buffer for data */
          int        length)            /* I - Number of bytes to write */
{
  return ((int)httpWrite2(http, buffer, (size_t)length));
}


/*
 * 'httpWrite2()' - Write data to a HTTP connection.
 *
 * @since CUPS 1.2/macOS 10.5@
 */

ssize_t                                 /* O - Number of bytes written */
httpWrite2(http_t     *http,            /* I - HTTP connection */
           const char *buffer,          /* I - Buffer for data */
           size_t     length)           /* I - Number of bytes to write */
{
  ssize_t       bytes;                  /* Bytes written */


  DEBUG_printf(("httpWrite2(http=%p, buffer=%p, length=" CUPS_LLFMT ")", (void *)http, (void *)buffer, CUPS_LLCAST length));

 /*
  * Range check input...
  */

  if (!http || !buffer)
  {
    DEBUG_puts("1httpWrite2: Returning -1 due to bad input.");
    return (-1);
  }

 /*
  * Mark activity on the connection...
  */

  http->activity = time(NULL);

 /*
  * Buffer small writes for better performance...
  */

#ifdef HAVE_LIBZ
  if (http->coding == _HTTP_CODING_GZIP || http->coding == _HTTP_CODING_DEFLATE)
  {
    DEBUG_printf(("1httpWrite2: http->coding=%d", http->coding));

    if (length == 0)
    {
      http_content_coding_finish(http);
      bytes = 0;
    }
    else
    {
      size_t    slen;                   /* Bytes to write */
      ssize_t   sret;                   /* Bytes written */

      http->stream.next_in   = (Bytef *)buffer;
      http->stream.avail_in  = (uInt)length;

      while (deflate(&(http->stream), Z_NO_FLUSH) == Z_OK)
      {
        DEBUG_printf(("1httpWrite2: avail_out=%d", http->stream.avail_out));

        if (http->stream.avail_out > 0)
          continue;

        slen = _HTTP_MAX_SBUFFER - http->stream.avail_out;

        DEBUG_printf(("1httpWrite2: Writing intermediate chunk, len=%d", (int)slen));

        if (slen > 0 && http->data_encoding == HTTP_ENCODING_CHUNKED)
          sret = http_write_chunk(http, (char *)http->sbuffer, slen);
        else if (slen > 0)
          sret = http_write(http, (char *)http->sbuffer, slen);
        else
          sret = 0;

        if (sret < 0)
        {
          DEBUG_puts("1httpWrite2: Unable to write, returning -1.");
          return (-1);
        }

        http->stream.next_out  = (Bytef *)http->sbuffer;
        http->stream.avail_out = (uInt)_HTTP_MAX_SBUFFER;
      }

      bytes = (ssize_t)length;
    }
  }
  else
#endif /* HAVE_LIBZ */
  if (length > 0)
  {
    if (http->wused && (length + (size_t)http->wused) > sizeof(http->wbuffer))
    {
      DEBUG_printf(("2httpWrite2: Flushing buffer (wused=%d, length="
                    CUPS_LLFMT ")", http->wused, CUPS_LLCAST length));

      httpFlushWrite(http);
    }

    if ((length + (size_t)http->wused) <= sizeof(http->wbuffer) && length < sizeof(http->wbuffer))
    {
     /*
      * Write to buffer...
      */

      DEBUG_printf(("2httpWrite2: Copying " CUPS_LLFMT " bytes to wbuffer...",
                    CUPS_LLCAST length));

      memcpy(http->wbuffer + http->wused, buffer, length);
      http->wused += (int)length;
      bytes = (ssize_t)length;
    }
    else
    {
     /*
      * Otherwise write the data directly...
      */

      DEBUG_printf(("2httpWrite2: Writing " CUPS_LLFMT " bytes to socket...",
                    CUPS_LLCAST length));

      if (http->data_encoding == HTTP_ENCODING_CHUNKED)
        bytes = (ssize_t)http_write_chunk(http, buffer, length);
      else
        bytes = (ssize_t)http_write(http, buffer, length);

      DEBUG_printf(("2httpWrite2: Wrote " CUPS_LLFMT " bytes...",
                    CUPS_LLCAST bytes));
    }

    if (http->data_encoding == HTTP_ENCODING_LENGTH)
      http->data_remaining -= bytes;
  }
  else
    bytes = 0;

 /*
  * Handle end-of-request processing...
  */

  if ((http->data_encoding == HTTP_ENCODING_CHUNKED && length == 0) ||
      (http->data_encoding == HTTP_ENCODING_LENGTH && http->data_remaining == 0))
  {
   /*
    * Finished with the transfer; unless we are sending POST or PUT
    * data, go idle...
    */

#ifdef HAVE_LIBZ
    if (http->coding == _HTTP_CODING_GZIP || http->coding == _HTTP_CODING_DEFLATE)
      http_content_coding_finish(http);
#endif /* HAVE_LIBZ */

    if (http->wused)
    {
      if (httpFlushWrite(http) < 0)
        return (-1);
    }

    if (http->data_encoding == HTTP_ENCODING_CHUNKED)
    {
     /*
      * Send a 0-length chunk at the end of the request...
      */

      http_write(http, "0\r\n\r\n", 5);

     /*
      * Reset the data state...
      */

      http->data_encoding  = HTTP_ENCODING_FIELDS;
      http->data_remaining = 0;
    }

    if (http->state == HTTP_STATE_POST_RECV)
      http->state ++;
    else if (http->state == HTTP_STATE_POST_SEND ||
             http->state == HTTP_STATE_GET_SEND)
      http->state = HTTP_STATE_WAITING;
    else
      http->state = HTTP_STATE_STATUS;

    DEBUG_printf(("2httpWrite2: Changed state to %s.",
                  httpStateString(http->state)));
  }

  DEBUG_printf(("1httpWrite2: Returning " CUPS_LLFMT ".", CUPS_LLCAST bytes));

  return (bytes);
}


/*
 * 'httpWriteResponse()' - Write a HTTP response to a client connection.
 *
 * @since CUPS 1.7/macOS 10.9@
 */

int                                     /* O - 0 on success, -1 on error */
httpWriteResponse(http_t        *http,  /* I - HTTP connection */
                  http_status_t status) /* I - Status code */
{
  http_encoding_t       old_encoding;   /* Old data_encoding value */
  off_t                 old_remaining;  /* Old data_remaining value */


 /*
  * Range check input...
  */

  DEBUG_printf(("httpWriteResponse(http=%p, status=%d)", (void *)http, status));

  if (!http || status < HTTP_STATUS_CONTINUE)
  {
    DEBUG_puts("1httpWriteResponse: Bad input.");
    return (-1);
  }

 /*
  * Set the various standard fields if they aren't already...
  */

  if (!http->fields[HTTP_FIELD_DATE])
    httpSetField(http, HTTP_FIELD_DATE, httpGetDateString(time(NULL)));

  if (status >= HTTP_STATUS_BAD_REQUEST && http->keep_alive)
  {
    http->keep_alive = HTTP_KEEPALIVE_OFF;
    httpSetField(http, HTTP_FIELD_KEEP_ALIVE, "");
  }

  if (http->version == HTTP_VERSION_1_1)
  {
    if (!http->fields[HTTP_FIELD_CONNECTION])
    {
      if (http->keep_alive)
        httpSetField(http, HTTP_FIELD_CONNECTION, "Keep-Alive");
      else
        httpSetField(http, HTTP_FIELD_CONNECTION, "close");
    }

    if (http->keep_alive && !http->fields[HTTP_FIELD_KEEP_ALIVE])
      httpSetField(http, HTTP_FIELD_KEEP_ALIVE, "timeout=10");
  }

#ifdef HAVE_SSL
  if (status == HTTP_STATUS_UPGRADE_REQUIRED ||
      status == HTTP_STATUS_SWITCHING_PROTOCOLS)
  {
    if (!http->fields[HTTP_FIELD_CONNECTION])
      httpSetField(http, HTTP_FIELD_CONNECTION, "Upgrade");

    if (!http->fields[HTTP_FIELD_UPGRADE])
      httpSetField(http, HTTP_FIELD_UPGRADE, "TLS/1.2,TLS/1.1,TLS/1.0");

    if (!http->fields[HTTP_FIELD_CONTENT_LENGTH])
      httpSetField(http, HTTP_FIELD_CONTENT_LENGTH, "0");
  }
#endif /* HAVE_SSL */

  if (!http->fields[HTTP_FIELD_SERVER])
    httpSetField(http, HTTP_FIELD_SERVER, http->default_fields[HTTP_FIELD_SERVER] ? http->default_fields[HTTP_FIELD_SERVER] : CUPS_MINIMAL);

 /*
  * Set the Accept-Encoding field if it isn't already...
  */

  if (!http->fields[HTTP_FIELD_ACCEPT_ENCODING])
    httpSetField(http, HTTP_FIELD_ACCEPT_ENCODING, http->default_fields[HTTP_FIELD_ACCEPT_ENCODING] ? http->default_fields[HTTP_FIELD_ACCEPT_ENCODING] :
#ifdef HAVE_LIBZ
                                                 "gzip, deflate, identity");
#else
                                                 "identity");
#endif /* HAVE_LIBZ */

 /*
  * Send the response header...
  */

  old_encoding        = http->data_encoding;
  old_remaining       = http->data_remaining;
  http->data_encoding = HTTP_ENCODING_FIELDS;

  if (httpPrintf(http, "HTTP/%d.%d %d %s\r\n", http->version / 100, http->version % 100, (int)status, httpStatus(status)) < 0)
  {
    http->status = HTTP_STATUS_ERROR;
    return (-1);
  }

  if (status != HTTP_STATUS_CONTINUE)
  {
   /*
    * 100 Continue doesn't have the rest of the response headers...
    */

    int         i;                      /* Looping var */
    const char  *value;                 /* Field value */

    for (i = 0; i < HTTP_FIELD_MAX; i ++)
    {
      if ((value = httpGetField(http, i)) != NULL && *value)
      {
        if (httpPrintf(http, "%s: %s\r\n", http_fields[i], value) < 1)
        {
          http->status = HTTP_STATUS_ERROR;
          return (-1);
        }
      }
    }

    if (http->cookie)
    {
      if (strchr(http->cookie, ';'))
      {
        if (httpPrintf(http, "Set-Cookie: %s\r\n", http->cookie) < 1)
        {
          http->status = HTTP_STATUS_ERROR;
          return (-1);
        }
      }
      else if (httpPrintf(http, "Set-Cookie: %s; path=/; httponly;%s\r\n", http->cookie, http->tls ? " secure;" : "") < 1)
      {
        http->status = HTTP_STATUS_ERROR;
        return (-1);
      }
    }

   /*
    * "Click-jacking" defense (STR #4492)...
    */

    if (httpPrintf(http, "X-Frame-Options: DENY\r\n"
                         "Content-Security-Policy: frame-ancestors 'none'\r\n") < 1)
    {
      http->status = HTTP_STATUS_ERROR;
      return (-1);
    }
  }

  if (httpWrite2(http, "\r\n", 2) < 2)
  {
    http->status = HTTP_STATUS_ERROR;
    return (-1);
  }

  if (httpFlushWrite(http) < 0)
  {
    http->status = HTTP_STATUS_ERROR;
    return (-1);
  }

  if (status == HTTP_STATUS_CONTINUE ||
      status == HTTP_STATUS_SWITCHING_PROTOCOLS)
  {
   /*
    * Restore the old data_encoding and data_length values...
    */

    http->data_encoding  = old_encoding;
    http->data_remaining = old_remaining;

    if (old_remaining <= INT_MAX)
      http->_data_remaining = (int)old_remaining;
    else
      http->_data_remaining = INT_MAX;
  }
  else if (http->state == HTTP_STATE_OPTIONS ||
           http->state == HTTP_STATE_HEAD ||
           http->state == HTTP_STATE_PUT ||
           http->state == HTTP_STATE_TRACE ||
           http->state == HTTP_STATE_CONNECT ||
           http->state == HTTP_STATE_STATUS)
  {
    DEBUG_printf(("1httpWriteResponse: Resetting state to HTTP_STATE_WAITING, "
                  "was %s.", httpStateString(http->state)));
    http->state = HTTP_STATE_WAITING;
  }
  else
  {
   /*
    * Force data_encoding and data_length to be set according to the response
    * headers...
    */

    http_set_length(http);

    if (http->data_encoding == HTTP_ENCODING_LENGTH && http->data_remaining == 0)
    {
      DEBUG_printf(("1httpWriteResponse: Resetting state to HTTP_STATE_WAITING, "
                    "was %s.", httpStateString(http->state)));
      http->state = HTTP_STATE_WAITING;
      return (0);
    }

    if (http->state == HTTP_STATE_POST_RECV || http->state == HTTP_STATE_GET)
      http->state ++;

#ifdef HAVE_LIBZ
   /*
    * Then start any content encoding...
    */

    DEBUG_puts("1httpWriteResponse: Calling http_content_coding_start.");
    http_content_coding_start(http,
                              httpGetField(http, HTTP_FIELD_CONTENT_ENCODING));
#endif /* HAVE_LIBZ */

  }

  return (0);
}


/*
 * 'http_add_field()' - Add a value for a HTTP field, appending if needed.
 */

static void
http_add_field(http_t       *http,      /* I - HTTP connection */
               http_field_t field,      /* I - HTTP field */
               const char   *value,     /* I - Value string */
               int          append)     /* I - Append value? */
{
  char          temp[1024];             /* Temporary value string */
  size_t        fieldlen,               /* Length of existing value */
                valuelen,               /* Length of value string */
                total;                  /* Total length of string */


  if (field == HTTP_FIELD_HOST)
  {
   /*
    * Special-case for Host: as we don't want a trailing "." on the hostname and
    * need to bracket IPv6 numeric addresses.
    */

    char *ptr = strchr(value, ':');

    if (value[0] != '[' && ptr && strchr(ptr + 1, ':'))
    {
     /*
      * Bracket IPv6 numeric addresses...
      *
      * This is slightly inefficient (basically copying twice), but is an edge
      * case and not worth optimizing...
      */

      snprintf(temp, sizeof(temp), "[%s]", value);
      value = temp;
    }
    else if (*value)
    {
     /*
      * Check for a trailing dot on the hostname...
      */

      strlcpy(temp, value, sizeof(temp));
      value = temp;
      ptr   = temp + strlen(temp) - 1;

      if (*ptr == '.')
        *ptr = '\0';
    }
  }

  if (append && field != HTTP_FIELD_ACCEPT_ENCODING && field != HTTP_FIELD_ACCEPT_LANGUAGE && field != HTTP_FIELD_ACCEPT_RANGES && field != HTTP_FIELD_ALLOW && field != HTTP_FIELD_LINK && field != HTTP_FIELD_TRANSFER_ENCODING && field != HTTP_FIELD_UPGRADE && field != HTTP_FIELD_WWW_AUTHENTICATE)
    append = 0;

  if (!append && http->fields[field])
  {
    if (http->fields[field] != http->_fields[field])
      free(http->fields[field]);

    http->fields[field] = NULL;
  }

  valuelen = strlen(value);

  if (!valuelen)
  {
    http->_fields[field][0] = '\0';
    return;
  }

  if (http->fields[field])
  {
    fieldlen = strlen(http->fields[field]);
    total    = fieldlen + 2 + valuelen;
  }
  else
  {
    fieldlen = 0;
    total    = valuelen;
  }

  if (total < HTTP_MAX_VALUE && field < HTTP_FIELD_ACCEPT_ENCODING)
  {
   /*
    * Copy short values to legacy char arrays (maintained for binary
    * compatibility with CUPS 1.2.x and earlier applications...)
    */

    if (fieldlen)
    {
      char      combined[HTTP_MAX_VALUE];
                                        /* Combined value string */

      snprintf(combined, sizeof(combined), "%s, %s", http->_fields[field], value);
      value = combined;
    }

    strlcpy(http->_fields[field], value, sizeof(http->_fields[field]));
    http->fields[field] = http->_fields[field];
  }
  else if (fieldlen)
  {
   /*
    * Expand the field value...
    */

    char        *combined;              /* New value string */

    if ((combined = realloc(http->fields[field], total + 1)) != NULL)
    {
      http->fields[field] = combined;
      strlcat(combined, ", ", total + 1);
      strlcat(combined, value, total + 1);
    }
  }
  else
  {
   /*
    * Allocate the field value...
    */

    http->fields[field] = strdup(value);
  }

#ifdef HAVE_LIBZ
  if (field == HTTP_FIELD_CONTENT_ENCODING && http->data_encoding != HTTP_ENCODING_FIELDS)
  {
    DEBUG_puts("1httpSetField: Calling http_content_coding_start.");
    http_content_coding_start(http, value);
  }
#endif /* HAVE_LIBZ */
}


#ifdef HAVE_LIBZ
/*
 * 'http_content_coding_finish()' - Finish doing any content encoding.
 */

static void
http_content_coding_finish(
    http_t *http)                       /* I - HTTP connection */
{
  int           zerr;                   /* Compression status */
  Byte          dummy[1];               /* Dummy read buffer */
  size_t        bytes;                  /* Number of bytes to write */


  DEBUG_printf(("http_content_coding_finish(http=%p)", (void *)http));
  DEBUG_printf(("1http_content_coding_finishing: http->coding=%d", http->coding));

  switch (http->coding)
  {
    case _HTTP_CODING_DEFLATE :
    case _HTTP_CODING_GZIP :
        http->stream.next_in  = dummy;
        http->stream.avail_in = 0;

        do
        {
          zerr  = deflate(&(http->stream), Z_FINISH);
          bytes = _HTTP_MAX_SBUFFER - http->stream.avail_out;

          if (bytes > 0)
          {
            DEBUG_printf(("1http_content_coding_finish: Writing trailing chunk, len=%d", (int)bytes));

            if (http->data_encoding == HTTP_ENCODING_CHUNKED)
              http_write_chunk(http, (char *)http->sbuffer, bytes);
            else
              http_write(http, (char *)http->sbuffer, bytes);
          }

          http->stream.next_out  = (Bytef *)http->sbuffer;
          http->stream.avail_out = (uInt)_HTTP_MAX_SBUFFER;
        }
        while (zerr == Z_OK);

        deflateEnd(&(http->stream));

        free(http->sbuffer);
        http->sbuffer = NULL;

        if (http->wused)
          httpFlushWrite(http);
        break;

    case _HTTP_CODING_INFLATE :
    case _HTTP_CODING_GUNZIP :
        inflateEnd(&(http->stream));
        free(http->sbuffer);
        http->sbuffer = NULL;
        break;

    default :
        break;
  }

  http->coding = _HTTP_CODING_IDENTITY;
}


/*
 * 'http_content_coding_start()' - Start doing content encoding.
 */

static void
http_content_coding_start(
    http_t     *http,                   /* I - HTTP connection */
    const char *value)                  /* I - Value of Content-Encoding */
{
  int                   zerr;           /* Error/status */
  _http_coding_t        coding;         /* Content coding value */


  DEBUG_printf(("http_content_coding_start(http=%p, value=\"%s\")", (void *)http, value));

  if (http->coding != _HTTP_CODING_IDENTITY)
  {
    DEBUG_printf(("1http_content_coding_start: http->coding already %d.",
                  http->coding));
    return;
  }
  else if (!strcmp(value, "x-gzip") || !strcmp(value, "gzip"))
  {
    if (http->state == HTTP_STATE_GET_SEND ||
        http->state == HTTP_STATE_POST_SEND)
      coding = http->mode == _HTTP_MODE_SERVER ? _HTTP_CODING_GZIP :
                                                 _HTTP_CODING_GUNZIP;
    else if (http->state == HTTP_STATE_POST_RECV ||
             http->state == HTTP_STATE_PUT_RECV)
      coding = http->mode == _HTTP_MODE_CLIENT ? _HTTP_CODING_GZIP :
                                                 _HTTP_CODING_GUNZIP;
    else
    {
      DEBUG_puts("1http_content_coding_start: Not doing content coding.");
      return;
    }
  }
  else if (!strcmp(value, "x-deflate") || !strcmp(value, "deflate"))
  {
    if (http->state == HTTP_STATE_GET_SEND ||
        http->state == HTTP_STATE_POST_SEND)
      coding = http->mode == _HTTP_MODE_SERVER ? _HTTP_CODING_DEFLATE :
                                                 _HTTP_CODING_INFLATE;
    else if (http->state == HTTP_STATE_POST_RECV ||
             http->state == HTTP_STATE_PUT_RECV)
      coding = http->mode == _HTTP_MODE_CLIENT ? _HTTP_CODING_DEFLATE :
                                                 _HTTP_CODING_INFLATE;
    else
    {
      DEBUG_puts("1http_content_coding_start: Not doing content coding.");
      return;
    }
  }
  else
  {
    DEBUG_puts("1http_content_coding_start: Not doing content coding.");
    return;
  }

  memset(&(http->stream), 0, sizeof(http->stream));

  switch (coding)
  {
    case _HTTP_CODING_DEFLATE :
    case _HTTP_CODING_GZIP :
        if (http->wused)
          httpFlushWrite(http);

        if ((http->sbuffer = malloc(_HTTP_MAX_SBUFFER)) == NULL)
        {
          http->status = HTTP_STATUS_ERROR;
          http->error  = errno;
          return;
        }

       /*
        * Window size for compression is 11 bits - optimal based on PWG Raster
        * sample files on pwg.org.  -11 is raw deflate, 27 is gzip, per ZLIB
        * documentation.
        */

        if ((zerr = deflateInit2(&(http->stream), Z_DEFAULT_COMPRESSION,
                                 Z_DEFLATED,
                                 coding == _HTTP_CODING_DEFLATE ? -11 : 27, 7,
                                 Z_DEFAULT_STRATEGY)) < Z_OK)
        {
          http->status = HTTP_STATUS_ERROR;
          http->error  = zerr == Z_MEM_ERROR ? ENOMEM : EINVAL;
          return;
        }

        http->stream.next_out  = (Bytef *)http->sbuffer;
        http->stream.avail_out = (uInt)_HTTP_MAX_SBUFFER;
        break;

    case _HTTP_CODING_INFLATE :
    case _HTTP_CODING_GUNZIP :
        if ((http->sbuffer = malloc(_HTTP_MAX_SBUFFER)) == NULL)
        {
          http->status = HTTP_STATUS_ERROR;
          http->error  = errno;
          return;
        }

       /*
        * Window size for decompression is up to 15 bits (maximum supported).
        * -15 is raw inflate, 31 is gunzip, per ZLIB documentation.
        */

        if ((zerr = inflateInit2(&(http->stream),
                                 coding == _HTTP_CODING_INFLATE ? -15 : 31))
                < Z_OK)
        {
          free(http->sbuffer);
          http->sbuffer = NULL;
          http->status  = HTTP_STATUS_ERROR;
          http->error   = zerr == Z_MEM_ERROR ? ENOMEM : EINVAL;
          return;
        }

        http->stream.avail_in = 0;
        http->stream.next_in  = http->sbuffer;
        break;

    default :
        break;
  }

  http->coding = coding;

  DEBUG_printf(("1http_content_coding_start: http->coding now %d.",
                http->coding));
}
#endif /* HAVE_LIBZ */


/*
 * 'http_create()' - Create an unconnected HTTP connection.
 */

static http_t *                         /* O - HTTP connection */
http_create(
    const char        *host,            /* I - Hostname */
    int               port,             /* I - Port number */
    http_addrlist_t   *addrlist,        /* I - Address list or @code NULL@ */
    int               family,           /* I - Address family or AF_UNSPEC */
    http_encryption_t encryption,       /* I - Encryption to use */
    int               blocking,         /* I - 1 for blocking mode */
    _http_mode_t      mode)             /* I - _HTTP_MODE_CLIENT or _SERVER */
{
  http_t        *http;                  /* New HTTP connection */
  char          service[255];           /* Service name */
  http_addrlist_t *myaddrlist = NULL;   /* My address list */


  DEBUG_printf(("4http_create(host=\"%s\", port=%d, addrlist=%p, family=%d, encryption=%d, blocking=%d, mode=%d)", host, port, (void *)addrlist, family, encryption, blocking, mode));

  if (!host && mode == _HTTP_MODE_CLIENT)
    return (NULL);

  httpInitialize();

 /*
  * Lookup the host...
  */

  if (addrlist)
  {
    myaddrlist = httpAddrCopyList(addrlist);
  }
  else
  {
    snprintf(service, sizeof(service), "%d", port);

    myaddrlist = httpAddrGetList(host, family, service);
  }

  if (!myaddrlist)
    return (NULL);

 /*
  * Allocate memory for the structure...
  */

  if ((http = calloc(sizeof(http_t), 1)) == NULL)
  {
    _cupsSetError(IPP_STATUS_ERROR_INTERNAL, strerror(errno), 0);
    httpAddrFreeList(myaddrlist);
    return (NULL);
  }

 /*
  * Initialize the HTTP data...
  */

  http->mode     = mode;
  http->activity = time(NULL);
  http->addrlist = myaddrlist;
  http->blocking = blocking;
  http->fd       = -1;
#ifdef HAVE_GSSAPI
  http->gssctx   = GSS_C_NO_CONTEXT;
  http->gssname  = GSS_C_NO_NAME;
#endif /* HAVE_GSSAPI */
  http->status   = HTTP_STATUS_CONTINUE;
  http->version  = HTTP_VERSION_1_1;

  if (host)
    strlcpy(http->hostname, host, sizeof(http->hostname));

  if (port == 443)                      /* Always use encryption for https */
    http->encryption = HTTP_ENCRYPTION_ALWAYS;
  else
    http->encryption = encryption;

  http_set_wait(http);

 /*
  * Return the new structure...
  */

  return (http);
}


#ifdef DEBUG
/*
 * 'http_debug_hex()' - Do a hex dump of a buffer.
 */

static void
http_debug_hex(const char *prefix,      /* I - Prefix for line */
               const char *buffer,      /* I - Buffer to dump */
               int        bytes)        /* I - Bytes to dump */
{
  int   i, j,                           /* Looping vars */
        ch;                             /* Current character */
  char  line[255],                      /* Line buffer */
        *start,                         /* Start of line after prefix */
        *ptr;                           /* Pointer into line */


  if (_cups_debug_fd < 0 || _cups_debug_level < 6)
    return;

  DEBUG_printf(("6%s: %d bytes:", prefix, bytes));

  snprintf(line, sizeof(line), "6%s: ", prefix);
  start = line + strlen(line);

  for (i = 0; i < bytes; i += 16)
  {
    for (j = 0, ptr = start; j < 16 && (i + j) < bytes; j ++, ptr += 2)
      snprintf(ptr, 3, "%02X", buffer[i + j] & 255);

    while (j < 16)
    {
      memcpy(ptr, "  ", 3);
      ptr += 2;
      j ++;
    }

    memcpy(ptr, "  ", 3);
    ptr += 2;

    for (j = 0; j < 16 && (i + j) < bytes; j ++)
    {
      ch = buffer[i + j] & 255;

      if (ch < ' ' || ch >= 127)
        ch = '.';

      *ptr++ = (char)ch;
    }

    *ptr = '\0';
    DEBUG_puts(line);
  }
}
#endif /* DEBUG */


/*
 * 'http_read()' - Read a buffer from a HTTP connection.
 *
 * This function does the low-level read from the socket, retrying and timing
 * out as needed.
 */

static ssize_t                          /* O - Number of bytes read or -1 on error */
http_read(http_t *http,                 /* I - HTTP connection */
          char   *buffer,               /* I - Buffer */
          size_t length)                /* I - Maximum bytes to read */
{
  ssize_t       bytes;                  /* Bytes read */


  DEBUG_printf(("http_read(http=%p, buffer=%p, length=" CUPS_LLFMT ")", (void *)http, (void *)buffer, CUPS_LLCAST length));

  if (!http->blocking || http->timeout_value > 0.0)
  {
    while (!httpWait(http, http->wait_value))
    {
      if (http->timeout_cb && (*http->timeout_cb)(http, http->timeout_data))
        continue;

      DEBUG_puts("2http_read: Timeout.");
      return (0);
    }
  }

  DEBUG_printf(("2http_read: Reading %d bytes into buffer.", (int)length));

  do
  {
#ifdef HAVE_SSL
    if (http->tls)
      bytes = _httpTLSRead(http, buffer, (int)length);
    else
#endif /* HAVE_SSL */
    bytes = recv(http->fd, buffer, length, 0);

    if (bytes < 0)
    {
#ifdef WIN32
      if (WSAGetLastError() != WSAEINTR)
      {
        http->error = WSAGetLastError();
        return (-1);
      }
      else if (WSAGetLastError() == WSAEWOULDBLOCK)
      {
        if (!http->timeout_cb ||
            !(*http->timeout_cb)(http, http->timeout_data))
        {
          http->error = WSAEWOULDBLOCK;
          return (-1);
        }
      }
#else
      DEBUG_printf(("2http_read: %s", strerror(errno)));

      if (errno == EWOULDBLOCK || errno == EAGAIN)
      {
        if (http->timeout_cb && !(*http->timeout_cb)(http, http->timeout_data))
        {
          http->error = errno;
          return (-1);
        }
        else if (!http->timeout_cb && errno != EAGAIN)
        {
          http->error = errno;
          return (-1);
        }
      }
      else if (errno != EINTR)
      {
        http->error = errno;
        return (-1);
      }
#endif /* WIN32 */
    }
  }
  while (bytes < 0);

  DEBUG_printf(("2http_read: Read " CUPS_LLFMT " bytes into buffer.",
                CUPS_LLCAST bytes));
#ifdef DEBUG
  if (bytes > 0)
    http_debug_hex("http_read", buffer, (int)bytes);
#endif /* DEBUG */

  if (bytes < 0)
  {
#ifdef WIN32
    if (WSAGetLastError() == WSAEINTR)
      bytes = 0;
    else
      http->error = WSAGetLastError();
#else
    if (errno == EINTR || (errno == EAGAIN && !http->timeout_cb))
      bytes = 0;
    else
      http->error = errno;
#endif /* WIN32 */
  }
  else if (bytes == 0)
  {
    http->error = EPIPE;
    return (0);
  }

  return (bytes);
}


/*
 * 'http_read_buffered()' - Do a buffered read from a HTTP connection.
 *
 * This function reads data from the HTTP buffer or from the socket, as needed.
 */

static ssize_t                          /* O - Number of bytes read or -1 on error */
http_read_buffered(http_t *http,        /* I - HTTP connection */
                   char   *buffer,      /* I - Buffer */
                   size_t length)       /* I - Maximum bytes to read */
{
  ssize_t       bytes;                  /* Bytes read */


  DEBUG_printf(("http_read_buffered(http=%p, buffer=%p, length=" CUPS_LLFMT ") used=%d", (void *)http, (void *)buffer, CUPS_LLCAST length, http->used));

  if (http->used > 0)
  {
    if (length > (size_t)http->used)
      bytes = (ssize_t)http->used;
    else
      bytes = (ssize_t)length;

    DEBUG_printf(("2http_read: Grabbing %d bytes from input buffer.",
                  (int)bytes));

    memcpy(buffer, http->buffer, (size_t)bytes);
    http->used -= (int)bytes;

    if (http->used > 0)
      memmove(http->buffer, http->buffer + bytes, (size_t)http->used);
  }
  else
    bytes = http_read(http, buffer, length);

  return (bytes);
}


/*
 * 'http_read_chunk()' - Read a chunk from a HTTP connection.
 *
 * This function reads and validates the chunk length, then does a buffered read
 * returning the number of bytes placed in the buffer.
 */

static ssize_t                          /* O - Number of bytes read or -1 on error */
http_read_chunk(http_t *http,           /* I - HTTP connection */
                char   *buffer,         /* I - Buffer */
                size_t length)          /* I - Maximum bytes to read */
{
  DEBUG_printf(("http_read_chunk(http=%p, buffer=%p, length=" CUPS_LLFMT ")", (void *)http, (void *)buffer, CUPS_LLCAST length));

  if (http->data_remaining <= 0)
  {
    char        len[32];                /* Length string */

    if (!httpGets(len, sizeof(len), http))
    {
      DEBUG_puts("1http_read_chunk: Could not get chunk length.");
      return (0);
    }

    if (!len[0])
    {
      DEBUG_puts("1http_read_chunk: Blank chunk length, trying again...");
      if (!httpGets(len, sizeof(len), http))
      {
        DEBUG_puts("1http_read_chunk: Could not get chunk length.");
        return (0);
      }
    }

    http->data_remaining = strtoll(len, NULL, 16);

    if (http->data_remaining < 0)
    {
      DEBUG_printf(("1http_read_chunk: Negative chunk length \"%s\" ("
                    CUPS_LLFMT ")", len, CUPS_LLCAST http->data_remaining));
      return (0);
    }

    DEBUG_printf(("2http_read_chunk: Got chunk length \"%s\" (" CUPS_LLFMT ")",
                  len, CUPS_LLCAST http->data_remaining));

    if (http->data_remaining == 0)
    {
     /*
      * 0-length chunk, grab trailing blank line...
      */

      httpGets(len, sizeof(len), http);
    }
  }

  DEBUG_printf(("2http_read_chunk: data_remaining=" CUPS_LLFMT,
                CUPS_LLCAST http->data_remaining));

  if (http->data_remaining <= 0)
    return (0);
  else if (length > (size_t)http->data_remaining)
    length = (size_t)http->data_remaining;

  return (http_read_buffered(http, buffer, length));
}


/*
 * 'http_send()' - Send a request with all fields and the trailing blank line.
 */

static int                              /* O - 0 on success, non-zero on error */
http_send(http_t       *http,           /* I - HTTP connection */
          http_state_t request,         /* I - Request code */
          const char   *uri)            /* I - URI */
{
  int           i;                      /* Looping var */
  char          buf[1024];              /* Encoded URI buffer */
  const char    *value;                 /* Field value */
  static const char * const codes[] =   /* Request code strings */
                {
                  NULL,
                  "OPTIONS",
                  "GET",
                  NULL,
                  "HEAD",
                  "POST",
                  NULL,
                  NULL,
                  "PUT",
                  NULL,
                  "DELETE",
                  "TRACE",
                  "CLOSE",
                  NULL,
                  NULL
                };


  DEBUG_printf(("4http_send(http=%p, request=HTTP_%s, uri=\"%s\")", (void *)http, codes[request], uri));

  if (http == NULL || uri == NULL)
    return (-1);

 /*
  * Set the User-Agent field if it isn't already...
  */

  if (!http->fields[HTTP_FIELD_USER_AGENT])
  {
    if (http->default_fields[HTTP_FIELD_USER_AGENT])
      httpSetField(http, HTTP_FIELD_USER_AGENT, http->default_fields[HTTP_FIELD_USER_AGENT]);
    else
      httpSetField(http, HTTP_FIELD_USER_AGENT, cupsUserAgent());
  }

 /*
  * Set the Accept-Encoding field if it isn't already...
  */

  if (!http->fields[HTTP_FIELD_ACCEPT_ENCODING] && http->default_fields[HTTP_FIELD_ACCEPT_ENCODING])
    httpSetField(http, HTTP_FIELD_ACCEPT_ENCODING, http->default_fields[HTTP_FIELD_ACCEPT_ENCODING]);

 /*
  * Encode the URI as needed...
  */

  _httpEncodeURI(buf, uri, sizeof(buf));

 /*
  * See if we had an error the last time around; if so, reconnect...
  */

  if (http->fd < 0 || http->status == HTTP_STATUS_ERROR ||
      http->status >= HTTP_STATUS_BAD_REQUEST)
  {
    DEBUG_printf(("5http_send: Reconnecting, fd=%d, status=%d, tls_upgrade=%d",
                  http->fd, http->status, http->tls_upgrade));

    if (httpReconnect2(http, 30000, NULL))
      return (-1);
  }

 /*
  * Flush any written data that is pending...
  */

  if (http->wused)
  {
    if (httpFlushWrite(http) < 0)
      if (httpReconnect2(http, 30000, NULL))
        return (-1);
  }

 /*
  * Send the request header...
  */

  http->state         = request;
  http->data_encoding = HTTP_ENCODING_FIELDS;

  if (request == HTTP_STATE_POST || request == HTTP_STATE_PUT)
    http->state ++;

  http->status = HTTP_STATUS_CONTINUE;

#ifdef HAVE_SSL
  if (http->encryption == HTTP_ENCRYPTION_REQUIRED && !http->tls)
  {
    httpSetField(http, HTTP_FIELD_CONNECTION, "Upgrade");
    httpSetField(http, HTTP_FIELD_UPGRADE, "TLS/1.2,TLS/1.1,TLS/1.0");
  }
#endif /* HAVE_SSL */

  if (httpPrintf(http, "%s %s HTTP/1.1\r\n", codes[request], buf) < 1)
  {
    http->status = HTTP_STATUS_ERROR;
    return (-1);
  }

  for (i = 0; i < HTTP_FIELD_MAX; i ++)
    if ((value = httpGetField(http, i)) != NULL && *value)
    {
      DEBUG_printf(("5http_send: %s: %s", http_fields[i], value));

      if (i == HTTP_FIELD_HOST)
      {
        if (httpPrintf(http, "Host: %s:%d\r\n", value,
                       httpAddrPort(http->hostaddr)) < 1)
        {
          http->status = HTTP_STATUS_ERROR;
          return (-1);
        }
      }
      else if (httpPrintf(http, "%s: %s\r\n", http_fields[i], value) < 1)
      {
        http->status = HTTP_STATUS_ERROR;
        return (-1);
      }
    }

  if (http->cookie)
    if (httpPrintf(http, "Cookie: $Version=0; %s\r\n", http->cookie) < 1)
    {
      http->status = HTTP_STATUS_ERROR;
      return (-1);
    }

  DEBUG_printf(("5http_send: expect=%d, mode=%d, state=%d", http->expect,
                http->mode, http->state));

  if (http->expect == HTTP_STATUS_CONTINUE && http->mode == _HTTP_MODE_CLIENT &&
      (http->state == HTTP_STATE_POST_RECV ||
       http->state == HTTP_STATE_PUT_RECV))
    if (httpPrintf(http, "Expect: 100-continue\r\n") < 1)
    {
      http->status = HTTP_STATUS_ERROR;
      return (-1);
    }

  if (httpPrintf(http, "\r\n") < 1)
  {
    http->status = HTTP_STATUS_ERROR;
    return (-1);
  }

  if (httpFlushWrite(http) < 0)
    return (-1);

  http_set_length(http);
  httpClearFields(http);

 /*
  * The Kerberos and AuthRef authentication strings can only be used once...
  */

  if (http->fields[HTTP_FIELD_AUTHORIZATION] && http->authstring &&
      (!strncmp(http->authstring, "Negotiate", 9) ||
       !strncmp(http->authstring, "AuthRef", 7)))
  {
    http->_authstring[0] = '\0';

    if (http->authstring != http->_authstring)
      free(http->authstring);

    http->authstring = http->_authstring;
  }

  return (0);
}


/*
 * 'http_set_length()' - Set the data_encoding and data_remaining values.
 */

static off_t                            /* O - Remainder or -1 on error */
http_set_length(http_t *http)           /* I - Connection */
{
  off_t remaining;                      /* Remainder */


  DEBUG_printf(("http_set_length(http=%p) mode=%d state=%s", (void *)http, http->mode, httpStateString(http->state)));

  if ((remaining = httpGetLength2(http)) >= 0)
  {
    if (http->mode == _HTTP_MODE_SERVER &&
        http->state != HTTP_STATE_GET_SEND &&
        http->state != HTTP_STATE_PUT &&
        http->state != HTTP_STATE_POST &&
        http->state != HTTP_STATE_POST_SEND)
    {
      DEBUG_puts("1http_set_length: Not setting data_encoding/remaining.");
      return (remaining);
    }

    if (!_cups_strcasecmp(httpGetField(http, HTTP_FIELD_TRANSFER_ENCODING), "chunked"))
    {
      DEBUG_puts("1http_set_length: Setting data_encoding to "
                 "HTTP_ENCODING_CHUNKED.");
      http->data_encoding = HTTP_ENCODING_CHUNKED;
    }
    else
    {
      DEBUG_puts("1http_set_length: Setting data_encoding to "
                 "HTTP_ENCODING_LENGTH.");
      http->data_encoding = HTTP_ENCODING_LENGTH;
    }

    DEBUG_printf(("1http_set_length: Setting data_remaining to " CUPS_LLFMT ".",
                  CUPS_LLCAST remaining));
    http->data_remaining = remaining;

    if (remaining <= INT_MAX)
      http->_data_remaining = (int)remaining;
    else
      http->_data_remaining = INT_MAX;
  }

  return (remaining);
}

/*
 * 'http_set_timeout()' - Set the socket timeout values.
 */

static void
http_set_timeout(int    fd,             /* I - File descriptor */
                 double timeout)        /* I - Timeout in seconds */
{
#ifdef WIN32
  DWORD tv = (DWORD)(timeout * 1000);
                                      /* Timeout in milliseconds */

  setsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, CUPS_SOCAST &tv, sizeof(tv));
  setsockopt(fd, SOL_SOCKET, SO_SNDTIMEO, CUPS_SOCAST &tv, sizeof(tv));

#else
  struct timeval tv;                    /* Timeout in secs and usecs */

  tv.tv_sec  = (int)timeout;
  tv.tv_usec = (int)(1000000 * fmod(timeout, 1.0));

  setsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, CUPS_SOCAST &tv, sizeof(tv));
  setsockopt(fd, SOL_SOCKET, SO_SNDTIMEO, CUPS_SOCAST &tv, sizeof(tv));
#endif /* WIN32 */
}


/*
 * 'http_set_wait()' - Set the default wait value for reads.
 */

static void
http_set_wait(http_t *http)             /* I - HTTP connection */
{
  if (http->blocking)
  {
    http->wait_value = (int)(http->timeout_value * 1000);

    if (http->wait_value <= 0)
      http->wait_value = 60000;
  }
  else
    http->wait_value = 10000;
}


#ifdef HAVE_SSL
/*
 * 'http_tls_upgrade()' - Force upgrade to TLS encryption.
 */

static int                              /* O - Status of connection */
http_tls_upgrade(http_t *http)          /* I - HTTP connection */
{
  int           ret;                    /* Return value */
  http_t        myhttp;                 /* Local copy of HTTP data */


  DEBUG_printf(("7http_tls_upgrade(%p)", (void *)http));

 /*
  * Flush the connection to make sure any previous "Upgrade" message
  * has been read.
  */

  httpFlush(http);

 /*
  * Copy the HTTP data to a local variable so we can do the OPTIONS
  * request without interfering with the existing request data...
  */

  memcpy(&myhttp, http, sizeof(myhttp));

 /*
  * Send an OPTIONS request to the server, requiring SSL or TLS
  * encryption on the link...
  */

  http->tls_upgrade = 1;
  memset(http->fields, 0, sizeof(http->fields));
  http->expect = (http_status_t)0;

  if (http->hostname[0] == '/')
    httpSetField(http, HTTP_FIELD_HOST, "localhost");
  else
    httpSetField(http, HTTP_FIELD_HOST, http->hostname);

  httpSetField(http, HTTP_FIELD_CONNECTION, "upgrade");
  httpSetField(http, HTTP_FIELD_UPGRADE, "TLS/1.2,TLS/1.1,TLS/1.0");

  if ((ret = httpOptions(http, "*")) == 0)
  {
   /*
    * Wait for the secure connection...
    */

    while (httpUpdate(http) == HTTP_STATUS_CONTINUE);
  }

 /*
  * Restore the HTTP request data...
  */

  memcpy(http->_fields, myhttp._fields, sizeof(http->_fields));
  memcpy(http->fields, myhttp.fields, sizeof(http->fields));

  http->data_encoding   = myhttp.data_encoding;
  http->data_remaining  = myhttp.data_remaining;
  http->_data_remaining = myhttp._data_remaining;
  http->expect          = myhttp.expect;
  http->digest_tries    = myhttp.digest_tries;
  http->tls_upgrade     = 0;

 /*
  * See if we actually went secure...
  */

  if (!http->tls)
  {
   /*
    * Server does not support HTTP upgrade...
    */

    DEBUG_puts("8http_tls_upgrade: Server does not support HTTP upgrade!");

    _cupsSetError(IPP_STATUS_ERROR_CUPS_PKI, _("Encryption is not supported."), 1);
    httpAddrClose(NULL, http->fd);

    http->fd = -1;

    return (-1);
  }
  else
    return (ret);
}
#endif /* HAVE_SSL */


/*
 * 'http_write()' - Write a buffer to a HTTP connection.
 */

static ssize_t                          /* O - Number of bytes written */
http_write(http_t     *http,            /* I - HTTP connection */
           const char *buffer,          /* I - Buffer for data */
           size_t     length)           /* I - Number of bytes to write */
{
  ssize_t       tbytes,                 /* Total bytes sent */
                bytes;                  /* Bytes sent */


  DEBUG_printf(("2http_write(http=%p, buffer=%p, length=" CUPS_LLFMT ")", (void *)http, (void *)buffer, CUPS_LLCAST length));
  http->error = 0;
  tbytes      = 0;

  while (length > 0)
  {
    DEBUG_printf(("3http_write: About to write %d bytes.", (int)length));

    if (http->timeout_value > 0.0)
    {
#ifdef HAVE_POLL
      struct pollfd     pfd;            /* Polled file descriptor */
#else
      fd_set            output_set;     /* Output ready for write? */
      struct timeval    timeout;        /* Timeout value */
#endif /* HAVE_POLL */
      int               nfds;           /* Result from select()/poll() */

      do
      {
#ifdef HAVE_POLL
        pfd.fd     = http->fd;
        pfd.events = POLLOUT;

        while ((nfds = poll(&pfd, 1, http->wait_value)) < 0 &&
               (errno == EINTR || errno == EAGAIN))
          /* do nothing */;

#else
        do
        {
          FD_ZERO(&output_set);
          FD_SET(http->fd, &output_set);

          timeout.tv_sec  = http->wait_value / 1000;
          timeout.tv_usec = 1000 * (http->wait_value % 1000);

          nfds = select(http->fd + 1, NULL, &output_set, NULL, &timeout);
        }
#  ifdef WIN32
        while (nfds < 0 && (WSAGetLastError() == WSAEINTR ||
                            WSAGetLastError() == WSAEWOULDBLOCK));
#  else
        while (nfds < 0 && (errno == EINTR || errno == EAGAIN));
#  endif /* WIN32 */
#endif /* HAVE_POLL */

        if (nfds < 0)
        {
          http->error = errno;
          return (-1);
        }
        else if (nfds == 0 && (!http->timeout_cb || !(*http->timeout_cb)(http, http->timeout_data)))
        {
#ifdef WIN32
          http->error = WSAEWOULDBLOCK;
#else
          http->error = EWOULDBLOCK;
#endif /* WIN32 */
          return (-1);
        }
      }
      while (nfds <= 0);
    }

#ifdef HAVE_SSL
    if (http->tls)
      bytes = _httpTLSWrite(http, buffer, (int)length);
    else
#endif /* HAVE_SSL */
    bytes = send(http->fd, buffer, length, 0);

    DEBUG_printf(("3http_write: Write of " CUPS_LLFMT " bytes returned "
                  CUPS_LLFMT ".", CUPS_LLCAST length, CUPS_LLCAST bytes));

    if (bytes < 0)
    {
#ifdef WIN32
      if (WSAGetLastError() == WSAEINTR)
        continue;
      else if (WSAGetLastError() == WSAEWOULDBLOCK)
      {
        if (http->timeout_cb && (*http->timeout_cb)(http, http->timeout_data))
          continue;

        http->error = WSAGetLastError();
      }
      else if (WSAGetLastError() != http->error &&
               WSAGetLastError() != WSAECONNRESET)
      {
        http->error = WSAGetLastError();
        continue;
      }

#else
      if (errno == EINTR)
        continue;
      else if (errno == EWOULDBLOCK || errno == EAGAIN)
      {
        if (http->timeout_cb && (*http->timeout_cb)(http, http->timeout_data))
          continue;
        else if (!http->timeout_cb && errno == EAGAIN)
          continue;

        http->error = errno;
      }
      else if (errno != http->error && errno != ECONNRESET)
      {
        http->error = errno;
        continue;
      }
#endif /* WIN32 */

      DEBUG_printf(("3http_write: error writing data (%s).",
                    strerror(http->error)));

      return (-1);
    }

    buffer += bytes;
    tbytes += bytes;
    length -= (size_t)bytes;
  }

#ifdef DEBUG
  http_debug_hex("http_write", buffer - tbytes, (int)tbytes);
#endif /* DEBUG */

  DEBUG_printf(("3http_write: Returning " CUPS_LLFMT ".", CUPS_LLCAST tbytes));

  return (tbytes);
}


/*
 * 'http_write_chunk()' - Write a chunked buffer.
 */

static ssize_t                          /* O - Number bytes written */
http_write_chunk(http_t     *http,      /* I - HTTP connection */
                 const char *buffer,    /* I - Buffer to write */
                 size_t        length)  /* I - Length of buffer */
{
  char          header[16];             /* Chunk header */
  ssize_t       bytes;                  /* Bytes written */


  DEBUG_printf(("7http_write_chunk(http=%p, buffer=%p, length=" CUPS_LLFMT ")", (void *)http, (void *)buffer, CUPS_LLCAST length));

 /*
  * Write the chunk header, data, and trailer.
  */

  snprintf(header, sizeof(header), "%x\r\n", (unsigned)length);
  if (http_write(http, header, strlen(header)) < 0)
  {
    DEBUG_puts("8http_write_chunk: http_write of length failed.");
    return (-1);
  }

  if ((bytes = http_write(http, buffer, length)) < 0)
  {
    DEBUG_puts("8http_write_chunk: http_write of buffer failed.");
    return (-1);
  }

  if (http_write(http, "\r\n", 2) < 0)
  {
    DEBUG_puts("8http_write_chunk: http_write of CR LF failed.");
    return (-1);
  }

  return (bytes);
}