Updated copyright

[thirdparty/squid.git] / src / http.cc

/*
 * $Id: http.cc,v 1.377 2001/01/12 00:37:18 wessels Exp $
 *
 * DEBUG: section 11    Hypertext Transfer Protocol (HTTP)
 * AUTHOR: Harvest Derived
 *
 * SQUID Web Proxy Cache          http://www.squid-cache.org/
 * ----------------------------------------------------------
 *
 *  Squid is the result of efforts by numerous individuals from
 *  the Internet community; see the CONTRIBUTORS file for full
 *  details.   Many organizations have provided support for Squid's
 *  development; see the SPONSORS file for full details.  Squid is
 *  Copyrighted (C) 2001 by the Regents of the University of
 *  California; see the COPYRIGHT file for full details.  Squid
 *  incorporates software developed and/or copyrighted by other
 *  sources; see the CREDITS file for full details.
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *  
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *  
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
 *
 */

/*
 * Anonymizing patch by lutz@as-node.jena.thur.de
 * have a look into http-anon.c to get more informations.
 */

#include "squid.h"

static const char *const crlf = "\r\n";

static CWCB httpSendComplete;
static CWCB httpSendRequestEntry;

static PF httpReadReply;
static void httpSendRequest(HttpStateData *);
static PF httpStateFree;
static PF httpTimeout;
static void httpCacheNegatively(StoreEntry *);
static void httpMakePrivate(StoreEntry *);
static void httpMakePublic(StoreEntry *);
static int httpCachableReply(HttpStateData *);
static void httpMaybeRemovePublic(StoreEntry *, http_status);

static void
httpStateFree(int fd, void *data)
{
    HttpStateData *httpState = data;
#if DELAY_POOLS
    delayClearNoDelay(fd);
#endif
    if (httpState == NULL)
        return;
    storeUnlockObject(httpState->entry);
    if (httpState->reply_hdr) {
        memFree(httpState->reply_hdr, MEM_8K_BUF);
        httpState->reply_hdr = NULL;
    }
    requestUnlink(httpState->request);
    requestUnlink(httpState->orig_request);
    httpState->request = NULL;
    httpState->orig_request = NULL;
    cbdataFree(httpState);
}

int
httpCachable(method_t method)
{
    /* GET and HEAD are cachable. Others are not. */
    if (method != METHOD_GET && method != METHOD_HEAD)
        return 0;
    /* else cachable */
    return 1;
}

static void
httpTimeout(int fd, void *data)
{
    HttpStateData *httpState = data;
    StoreEntry *entry = httpState->entry;
    debug(11, 4) ("httpTimeout: FD %d: '%s'\n", fd, storeUrl(entry));
    if (entry->store_status == STORE_PENDING) {
        if (entry->mem_obj->inmem_hi == 0) {
            fwdFail(httpState->fwd,
                errorCon(ERR_READ_TIMEOUT, HTTP_GATEWAY_TIMEOUT));
        }
    }
    comm_close(fd);
}

/* This object can be cached for a long time */
static void
httpMakePublic(StoreEntry * entry)
{
    if (EBIT_TEST(entry->flags, ENTRY_CACHABLE))
        storeSetPublicKey(entry);
}

/* This object should never be cached at all */
static void
httpMakePrivate(StoreEntry * entry)
{
    storeExpireNow(entry);
    storeReleaseRequest(entry); /* delete object when not used */
    /* storeReleaseRequest clears ENTRY_CACHABLE flag */
}

/* This object may be negatively cached */
static void
httpCacheNegatively(StoreEntry * entry)
{
    storeNegativeCache(entry);
    if (EBIT_TEST(entry->flags, ENTRY_CACHABLE))
        storeSetPublicKey(entry);
}

static void
httpMaybeRemovePublic(StoreEntry * e, http_status status)
{
    int remove = 0;
    int forbidden = 0;
    StoreEntry *pe;
    if (!EBIT_TEST(e->flags, KEY_PRIVATE))
        return;
    switch (status) {
    case HTTP_OK:
    case HTTP_NON_AUTHORITATIVE_INFORMATION:
    case HTTP_MULTIPLE_CHOICES:
    case HTTP_MOVED_PERMANENTLY:
    case HTTP_MOVED_TEMPORARILY:
    case HTTP_GONE:
    case HTTP_NOT_FOUND:
        remove = 1;
        break;
    case HTTP_FORBIDDEN:
    case HTTP_METHOD_NOT_ALLOWED:
        forbidden = 1;
        break;
#if WORK_IN_PROGRESS
    case HTTP_UNAUTHORIZED:
        forbidden = 1;
        break;
#endif
    default:
#if QUESTIONABLE
        /*
         * Any 2xx response should eject previously cached entities...
         */
        if (status >= 200 && status < 300)
            remove = 1;
#endif
        break;
    }
    if (!remove && !forbidden)
        return;
    assert(e->mem_obj);
    if ((pe = storeGetPublic(e->mem_obj->url, e->mem_obj->method)) != NULL) {
        assert(e != pe);
        storeRelease(pe);
    }
    /*
     * Also remove any cached HEAD response in case the object has
     * changed.
     */
    if ((pe = storeGetPublic(e->mem_obj->url, METHOD_HEAD)) != NULL) {
        assert(e != pe);
        storeRelease(pe);
    }
    if (forbidden)
        return;
    switch (e->mem_obj->method) {
    case METHOD_PUT:
    case METHOD_DELETE:
    case METHOD_PROPPATCH:
    case METHOD_MKCOL:
    case METHOD_MOVE:
    case METHOD_BMOVE:
    case METHOD_BDELETE:
        /*
         * Remove any cached GET object if it is beleived that the
         * object may have changed as a result of other methods
         */
        if ((pe = storeGetPublic(e->mem_obj->url, METHOD_GET)) != NULL) {
            assert(e != pe);
            storeRelease(pe);
        }
        break;
    }
}

static int
httpCachableReply(HttpStateData * httpState)
{
    HttpReply *rep = httpState->entry->mem_obj->reply;
    HttpHeader *hdr = &rep->header;
    const int cc_mask = (rep->cache_control) ? rep->cache_control->mask : 0;
    const char *v;
    if (EBIT_TEST(cc_mask, CC_PRIVATE))
        return 0;
    if (EBIT_TEST(cc_mask, CC_NO_CACHE))
        return 0;
    if (EBIT_TEST(cc_mask, CC_NO_STORE))
        return 0;
    if (httpState->request->flags.auth) {
        /*
         * Responses to requests with authorization may be cached
         * only if a Cache-Control: public reply header is present.
         * RFC 2068, sec 14.9.4
         */
        if (!EBIT_TEST(cc_mask, CC_PUBLIC))
            return 0;
    }
    /*
     * We don't properly deal with Vary features yet, so we can't
     * cache these
     */
    if (httpHeaderHas(hdr, HDR_VARY))
        return 0;
    /* Pragma: no-cache in _replies_ is not documented in HTTP,
     * but servers like "Active Imaging Webcast/2.0" sure do use it */
    if (httpHeaderHas(hdr, HDR_PRAGMA)) {
        String s = httpHeaderGetList(hdr, HDR_PRAGMA);
        const int no_cache = strListIsMember(&s, "no-cache", ',');
        stringClean(&s);
        if (no_cache)
            return 0;
    }
    /*
     * The "multipart/x-mixed-replace" content type is used for
     * continuous push replies.  These are generally dynamic and
     * probably should not be cachable
     */
    if ((v = httpHeaderGetStr(hdr, HDR_CONTENT_TYPE)))
        if (!strncasecmp(v, "multipart/x-mixed-replace", 25))
            return 0;
    switch (httpState->entry->mem_obj->reply->sline.status) {
        /* Responses that are cacheable */
    case HTTP_OK:
    case HTTP_NON_AUTHORITATIVE_INFORMATION:
    case HTTP_MULTIPLE_CHOICES:
    case HTTP_MOVED_PERMANENTLY:
    case HTTP_GONE:
        /*
         * Don't cache objects that need to be refreshed on next request,
         * unless we know how to refresh it.
         */
        if (!refreshIsCachable(httpState->entry))
            return 0;
        /* don't cache objects from peers w/o LMT, Date, or Expires */
        /* check that is it enough to check headers @?@ */
        if (rep->date > -1)
            return 1;
        else if (rep->last_modified > -1)
            return 1;
        else if (!httpState->peer)
            return 1;
        /* @?@ (here and 302): invalid expires header compiles to squid_curtime */
        else if (rep->expires > -1)
            return 1;
        else
            return 0;
        /* NOTREACHED */
        break;
        /* Responses that only are cacheable if the server says so */
    case HTTP_MOVED_TEMPORARILY:
        if (rep->expires > -1)
            return 1;
        else
            return 0;
        /* NOTREACHED */
        break;
        /* Errors can be negatively cached */
    case HTTP_NO_CONTENT:
    case HTTP_USE_PROXY:
    case HTTP_BAD_REQUEST:
    case HTTP_FORBIDDEN:
    case HTTP_NOT_FOUND:
    case HTTP_METHOD_NOT_ALLOWED:
    case HTTP_REQUEST_URI_TOO_LARGE:
    case HTTP_INTERNAL_SERVER_ERROR:
    case HTTP_NOT_IMPLEMENTED:
    case HTTP_BAD_GATEWAY:
    case HTTP_SERVICE_UNAVAILABLE:
    case HTTP_GATEWAY_TIMEOUT:
        return -1;
        /* NOTREACHED */
        break;
        /* Some responses can never be cached */
    case HTTP_PARTIAL_CONTENT:  /* Not yet supported */
    case HTTP_SEE_OTHER:
    case HTTP_NOT_MODIFIED:
    case HTTP_UNAUTHORIZED:
    case HTTP_PROXY_AUTHENTICATION_REQUIRED:
    case HTTP_INVALID_HEADER:   /* Squid header parsing error */
    default:                    /* Unknown status code */
        return 0;
        /* NOTREACHED */
        break;
    }
    /* NOTREACHED */
}

/* rewrite this later using new interfaces @?@ */
void
httpProcessReplyHeader(HttpStateData * httpState, const char *buf, int size)
{
    char *t = NULL;
    StoreEntry *entry = httpState->entry;
    int room;
    size_t hdr_len;
    HttpReply *reply = entry->mem_obj->reply;
    Ctx ctx;
    debug(11, 3) ("httpProcessReplyHeader: key '%s'\n",
        storeKeyText(entry->hash.key));
    if (httpState->reply_hdr == NULL)
        httpState->reply_hdr = memAllocate(MEM_8K_BUF);
    assert(httpState->reply_hdr_state == 0);
    hdr_len = httpState->reply_hdr_size;
    room = 8191 - hdr_len;
    xmemcpy(httpState->reply_hdr + hdr_len, buf, room < size ? room : size);
    hdr_len += room < size ? room : size;
    httpState->reply_hdr[hdr_len] = '\0';
    httpState->reply_hdr_size = hdr_len;
    if (hdr_len > 4 && strncmp(httpState->reply_hdr, "HTTP/", 5)) {
        debug(11, 3) ("httpProcessReplyHeader: Non-HTTP-compliant header: '%s'\n", httpState->reply_hdr);
        httpState->reply_hdr_state += 2;
        reply->sline.status = HTTP_INVALID_HEADER;
        return;
    }
    t = httpState->reply_hdr + hdr_len;
    /* headers can be incomplete only if object still arriving */
    if (!httpState->eof) {
        size_t k = headersEnd(httpState->reply_hdr, 8192);
        if (0 == k)
            return;             /* headers not complete */
        t = httpState->reply_hdr + k;
    }
    *t = '\0';
    httpState->reply_hdr_state++;
    assert(httpState->reply_hdr_state == 1);
    ctx = ctx_enter(entry->mem_obj->url);
    httpState->reply_hdr_state++;
    debug(11, 9) ("GOT HTTP REPLY HDR:\n---------\n%s\n----------\n",
        httpState->reply_hdr);
    /* Parse headers into reply structure */
    /* what happens if we fail to parse here? */
    httpReplyParse(reply, httpState->reply_hdr, hdr_len);
    storeTimestampsSet(entry);
    /* Check if object is cacheable or not based on reply code */
    debug(11, 3) ("httpProcessReplyHeader: HTTP CODE: %d\n", reply->sline.status);
    if (neighbors_do_private_keys)
        httpMaybeRemovePublic(entry, reply->sline.status);
    switch (httpCachableReply(httpState)) {
    case 1:
        httpMakePublic(entry);
        break;
    case 0:
        httpMakePrivate(entry);
        break;
    case -1:
        httpCacheNegatively(entry);
        break;
    default:
        assert(0);
        break;
    }
    if (reply->cache_control) {
        if (EBIT_TEST(reply->cache_control->mask, CC_PROXY_REVALIDATE))
            EBIT_SET(entry->flags, ENTRY_REVALIDATE);
        else if (EBIT_TEST(reply->cache_control->mask, CC_MUST_REVALIDATE))
            EBIT_SET(entry->flags, ENTRY_REVALIDATE);
    }
    if (httpState->flags.keepalive)
        if (httpState->peer)
            httpState->peer->stats.n_keepalives_sent++;
    if (reply->keep_alive)
        if (httpState->peer)
            httpState->peer->stats.n_keepalives_recv++;
    if (reply->date > -1 && !httpState->peer) {
        int skew = abs(reply->date - squid_curtime);
        if (skew > 86400)
            debug(11, 3) ("%s's clock is skewed by %d seconds!\n",
                httpState->request->host, skew);
    }
    ctx_exit(ctx);
#if HEADERS_LOG
    headersLog(1, 0, httpState->request->method, reply);
#endif
}

static int
httpPconnTransferDone(HttpStateData * httpState)
{
    /* return 1 if we got the last of the data on a persistent connection */
    MemObject *mem = httpState->entry->mem_obj;
    HttpReply *reply = mem->reply;
    int clen;
    debug(11, 3) ("httpPconnTransferDone: FD %d\n", httpState->fd);
    /*
     * If we didn't send a keep-alive request header, then this
     * can not be a persistent connection.
     */
    if (!httpState->flags.keepalive)
        return 0;
    /*
     * What does the reply have to say about keep-alive?
     */
    /*
     * XXX BUG?
     * If the origin server (HTTP/1.0) does not send a keep-alive
     * header, but keeps the connection open anyway, what happens?
     * We'll return here and http.c waits for an EOF before changing
     * store_status to STORE_OK.   Combine this with ENTRY_FWD_HDR_WAIT
     * and an error status code, and we might have to wait until
     * the server times out the socket.
     */
    if (!reply->keep_alive)
        return 0;
    debug(11, 5) ("httpPconnTransferDone: content_length=%d\n",
        reply->content_length);
    /* If we haven't seen the end of reply headers, we are not done */
    if (httpState->reply_hdr_state < 2)
        return 0;
    clen = httpReplyBodySize(httpState->request->method, reply);
    /* If there is no message body, we can be persistent */
    if (0 == clen)
        return 1;
    /* If the body size is unknown we must wait for EOF */
    if (clen < 0)
        return 0;
    /* If the body size is known, we must wait until we've gotten all of it.  */
    if (mem->inmem_hi < reply->content_length + reply->hdr_sz)
        return 0;
    /* We got it all */
    return 1;
}

/* This will be called when data is ready to be read from fd.  Read until
 * error or connection closed. */
/* XXX this function is too long! */
static void
httpReadReply(int fd, void *data)
{
    HttpStateData *httpState = data;
    LOCAL_ARRAY(char, buf, SQUID_TCP_SO_RCVBUF);
    StoreEntry *entry = httpState->entry;
    const request_t *request = httpState->request;
    int len;
    int bin;
    int clen;
    size_t read_sz;
#if DELAY_POOLS
    delay_id delay_id;

    /* special "if" only for http (for nodelay proxy conns) */
    if (delayIsNoDelay(fd))
        delay_id = 0;
    else
        delay_id = delayMostBytesAllowed(entry->mem_obj);
#endif
    if (EBIT_TEST(entry->flags, ENTRY_ABORTED)) {
        comm_close(fd);
        return;
    }
    /* check if we want to defer reading */
    errno = 0;
    read_sz = SQUID_TCP_SO_RCVBUF;
#if DELAY_POOLS
    read_sz = delayBytesWanted(delay_id, 1, read_sz);
#endif
    statCounter.syscalls.sock.reads++;
    len = read(fd, buf, read_sz);
    debug(11, 5) ("httpReadReply: FD %d: len %d.\n", fd, len);
    if (len > 0) {
        fd_bytes(fd, len, FD_READ);
#if DELAY_POOLS
        delayBytesIn(delay_id, len);
#endif
        kb_incr(&statCounter.server.all.kbytes_in, len);
        kb_incr(&statCounter.server.http.kbytes_in, len);
        commSetTimeout(fd, Config.Timeout.read, NULL, NULL);
        IOStats.Http.reads++;
        for (clen = len - 1, bin = 0; clen; bin++)
            clen >>= 1;
        IOStats.Http.read_hist[bin]++;
    }
    if (!httpState->reply_hdr && len > 0) {
        /* Skip whitespace */
        while (len > 0 && xisspace(*buf))
            xmemmove(buf, buf + 1, len--);
        if (len == 0) {
            /* Continue to read... */
            commSetSelect(fd, COMM_SELECT_READ, httpReadReply, httpState, 0);
            return;
        }
    }
    if (len < 0) {
        debug(50, 2) ("httpReadReply: FD %d: read failure: %s.\n",
            fd, xstrerror());
        if (ignoreErrno(errno)) {
            commSetSelect(fd, COMM_SELECT_READ, httpReadReply, httpState, 0);
        } else if (entry->mem_obj->inmem_hi == 0) {
            ErrorState *err;
            err = errorCon(ERR_READ_ERROR, HTTP_INTERNAL_SERVER_ERROR);
            err->xerrno = errno;
            fwdFail(httpState->fwd, err);
            comm_close(fd);
        } else {
            comm_close(fd);
        }
    } else if (len == 0 && entry->mem_obj->inmem_hi == 0) {
        ErrorState *err;
        err = errorCon(ERR_ZERO_SIZE_OBJECT, HTTP_SERVICE_UNAVAILABLE);
        err->xerrno = errno;
        fwdFail(httpState->fwd, err);
        httpState->eof = 1;
        comm_close(fd);
    } else if (len == 0) {
        /* Connection closed; retrieval done. */
        httpState->eof = 1;
        if (httpState->reply_hdr_state < 2)
            /*
             * Yes Henrik, there is a point to doing this.  When we
             * called httpProcessReplyHeader() before, we didn't find
             * the end of headers, but now we are definately at EOF, so
             * we want to process the reply headers.
             */
            httpProcessReplyHeader(httpState, buf, len);
        fwdComplete(httpState->fwd);
        comm_close(fd);
    } else {
        if (httpState->reply_hdr_state < 2) {
            httpProcessReplyHeader(httpState, buf, len);
            if (httpState->reply_hdr_state == 2) {
                http_status s = entry->mem_obj->reply->sline.status;
#if WIP_FWD_LOG
                fwdStatus(httpState->fwd, s);
#endif
                /*
                 * If its not a reply that we will re-forward, then
                 * allow the client to get it.
                 */
                if (!fwdReforwardableStatus(s))
                    EBIT_CLR(entry->flags, ENTRY_FWD_HDR_WAIT);
            }
        }
        storeAppend(entry, buf, len);
        if (EBIT_TEST(entry->flags, ENTRY_ABORTED)) {
            /*
             * the above storeAppend() call could ABORT this entry,
             * in that case, the server FD should already be closed.
             * there's nothing for us to do.
             */
            (void) 0;
        } else if (httpPconnTransferDone(httpState)) {
            /* yes we have to clear all these! */
            commSetDefer(fd, NULL, NULL);
            commSetTimeout(fd, -1, NULL, NULL);
            commSetSelect(fd, COMM_SELECT_READ, NULL, NULL, 0);
#if DELAY_POOLS
            delayClearNoDelay(fd);
#endif
            comm_remove_close_handler(fd, httpStateFree, httpState);
            fwdUnregister(fd, httpState->fwd);
            pconnPush(fd, request->host, request->port);
            fwdComplete(httpState->fwd);
            httpState->fd = -1;
            httpStateFree(fd, httpState);
        } else {
            /* Wait for EOF condition */
            commSetSelect(fd, COMM_SELECT_READ, httpReadReply, httpState, 0);
        }
    }
}

/* This will be called when request write is complete. Schedule read of
 * reply. */
static void
httpSendComplete(int fd, char *bufnotused, size_t size, int errflag, void *data)
{
    HttpStateData *httpState = data;
    StoreEntry *entry = httpState->entry;
    ErrorState *err;
    debug(11, 5) ("httpSendComplete: FD %d: size %d: errflag %d.\n",
        fd, size, errflag);
#if URL_CHECKSUM_DEBUG
    assert(entry->mem_obj->chksum == url_checksum(entry->mem_obj->url));
#endif
    if (size > 0) {
        fd_bytes(fd, size, FD_WRITE);
        kb_incr(&statCounter.server.all.kbytes_out, size);
        kb_incr(&statCounter.server.http.kbytes_out, size);
    }
    if (errflag == COMM_ERR_CLOSING)
        return;
    if (errflag) {
        err = errorCon(ERR_WRITE_ERROR, HTTP_INTERNAL_SERVER_ERROR);
        err->xerrno = errno;
        err->request = requestLink(httpState->orig_request);
        errorAppendEntry(entry, err);
        comm_close(fd);
        return;
    } else {
        /* Schedule read reply. */
        commSetSelect(fd, COMM_SELECT_READ, httpReadReply, httpState, 0);
        /*
         * Set the read timeout here because it hasn't been set yet.
         * We only set the read timeout after the request has been
         * fully written to the server-side.  If we start the timeout
         * after connection establishment, then we are likely to hit
         * the timeout for POST/PUT requests that have very large
         * request bodies.
         */
        commSetTimeout(fd, Config.Timeout.read, httpTimeout, httpState);
        commSetDefer(fd, fwdCheckDeferRead, entry);
    }
}

/*
 * build request headers and append them to a given MemBuf 
 * used by httpBuildRequestPrefix()
 * note: calls httpHeaderInit(), the caller is responsible for Clean()-ing
 */
void
httpBuildRequestHeader(request_t * request,
    request_t * orig_request,
    StoreEntry * entry,
    HttpHeader * hdr_out,
    int cfd,
    http_state_flags flags)
{
    /* building buffer for complex strings */
#define BBUF_SZ (MAX_URL+32)
    LOCAL_ARRAY(char, bbuf, BBUF_SZ);
    String strConnection = StringNull;
    const HttpHeader *hdr_in = &orig_request->header;
    int we_do_ranges;
    const HttpHeaderEntry *e;
    String strVia;
    String strFwd;
    HttpHeaderPos pos = HttpHeaderInitPos;
    httpHeaderInit(hdr_out, hoRequest);
    /* append our IMS header */
    if (request->lastmod > -1 && request->method == METHOD_GET)
        httpHeaderPutTime(hdr_out, HDR_IF_MODIFIED_SINCE, request->lastmod);

    /* decide if we want to do Ranges ourselves 
     * (and fetch the whole object now)
     * We want to handle Ranges ourselves iff
     *    - we can actually parse client Range specs
     *    - the specs are expected to be simple enough (e.g. no out-of-order ranges)
     *    - reply will be cachable
     * (If the reply will be uncachable we have to throw it away after 
     *  serving this request, so it is better to forward ranges to 
     *  the server and fetch only the requested content) 
     */
    if (NULL == orig_request->range)
        we_do_ranges = 0;
    else if (!orig_request->flags.cachable)
        we_do_ranges = 0;
    else if (httpHdrRangeOffsetLimit(orig_request->range))
        we_do_ranges = 0;
    else
        we_do_ranges = 1;
    debug(11, 8) ("httpBuildRequestHeader: range specs: %p, cachable: %d; we_do_ranges: %d\n",
        orig_request->range, orig_request->flags.cachable, we_do_ranges);

    strConnection = httpHeaderGetList(hdr_in, HDR_CONNECTION);
    while ((e = httpHeaderGetEntry(hdr_in, &pos))) {
        debug(11, 5) ("httpBuildRequestHeader: %s: %s\n",
            strBuf(e->name), strBuf(e->value));
        if (!httpRequestHdrAllowed(e, &strConnection)) {
            debug(11, 2) ("'%s' header denied by anonymize_headers configuration\n",
                strBuf(e->name));
            continue;
        }
        switch (e->id) {
        case HDR_PROXY_AUTHORIZATION:
            /* Only pass on proxy authentication to peers for which
             * authentication forwarding is explicitly enabled
             */
            if (request->flags.proxying && orig_request->peer_login &&
                strcmp(orig_request->peer_login, "PASS") == 0) {
                httpHeaderAddEntry(hdr_out, httpHeaderEntryClone(e));
            }
            break;
        case HDR_AUTHORIZATION:
            /* Pass on WWW authentication even if used locally. If this is
             * not wanted in an accelerator then the header can be removed
             * using the anonymization functions
             */
            httpHeaderAddEntry(hdr_out, httpHeaderEntryClone(e));
            /* XXX Some accelerators might want to strip the header
             * and regard the reply as cacheable, but authentication
             * is not normally enabled for accelerators without reading
             * the code, so there is not much use in adding logics here
             * without first defining the concept of having authentication
             * in the accelerator...
             */
            break;
        case HDR_HOST:
            /*
             * Normally Squid does not copy the Host: header from
             * a client request into the forwarded request headers.
             * However, there is one case when we do: If the URL
             * went through our redirector and the admin configured
             * 'redir_rewrites_host' to be off.
             */
            if (request->flags.redirected)
                if (!Config.onoff.redir_rewrites_host)
                    httpHeaderAddEntry(hdr_out, httpHeaderEntryClone(e));
            break;
        case HDR_IF_MODIFIED_SINCE:
            /* append unless we added our own;
             * note: at most one client's ims header can pass through */
            if (!httpHeaderHas(hdr_out, HDR_IF_MODIFIED_SINCE))
                httpHeaderAddEntry(hdr_out, httpHeaderEntryClone(e));
            break;
        case HDR_MAX_FORWARDS:
            if (orig_request->method == METHOD_TRACE) {
                /* sacrificing efficiency over clarity, etc. */
                const int hops = httpHeaderGetInt(hdr_in, HDR_MAX_FORWARDS);
                if (hops > 0)
                    httpHeaderPutInt(hdr_out, HDR_MAX_FORWARDS, hops - 1);
            }
            break;
        case HDR_RANGE:
        case HDR_IF_RANGE:
        case HDR_REQUEST_RANGE:
            if (!we_do_ranges)
                httpHeaderAddEntry(hdr_out, httpHeaderEntryClone(e));
            break;
        case HDR_PROXY_CONNECTION:
        case HDR_CONNECTION:
        case HDR_VIA:
        case HDR_X_FORWARDED_FOR:
        case HDR_CACHE_CONTROL:
            /* append these after the loop if needed */
            break;
        default:
            /* pass on all other header fields */
            httpHeaderAddEntry(hdr_out, httpHeaderEntryClone(e));
        }
    }

    /* append Via */
    strVia = httpHeaderGetList(hdr_in, HDR_VIA);
    snprintf(bbuf, BBUF_SZ, "%d.%d %s",
        orig_request->http_ver.major,
        orig_request->http_ver.minor, ThisCache);
    strListAdd(&strVia, bbuf, ',');
    httpHeaderPutStr(hdr_out, HDR_VIA, strBuf(strVia));
    stringClean(&strVia);

    /* append X-Forwarded-For */
    strFwd = httpHeaderGetList(hdr_in, HDR_X_FORWARDED_FOR);
    strListAdd(&strFwd, (cfd < 0 ? "unknown" : fd_table[cfd].ipaddr), ',');
    httpHeaderPutStr(hdr_out, HDR_X_FORWARDED_FOR, strBuf(strFwd));
    stringClean(&strFwd);

    /* append Host if not there already */
    if (!httpHeaderHas(hdr_out, HDR_HOST)) {
        /* use port# only if not default */
        if (orig_request->port == urlDefaultPort(orig_request->protocol)) {
            httpHeaderPutStr(hdr_out, HDR_HOST, orig_request->host);
        } else {
            httpHeaderPutStrf(hdr_out, HDR_HOST, "%s:%d",
                orig_request->host, (int) orig_request->port);
        }
    }
    /* append Authorization if known in URL, not in header and going direct */
    if (!httpHeaderHas(hdr_out, HDR_AUTHORIZATION)) {
        if (!request->flags.proxying && *request->login) {
            httpHeaderPutStrf(hdr_out, HDR_AUTHORIZATION, "Basic %s",
                base64_encode(request->login));
        }
    }
    /* append Proxy-Authorization if configured for peer, and proxying */
    if (request->flags.proxying && orig_request->peer_login &&
        !httpHeaderHas(hdr_out, HDR_PROXY_AUTHORIZATION) &&
        strcmp(orig_request->peer_login, "PASS") != 0) {
        if (*orig_request->peer_login == '*') {
            /* Special mode, to pass the username to the upstream cache */
            char loginbuf[256];
            char *username = "-";
            if (orig_request->auth_user_request)
                username = authenticateUserRequestUsername(orig_request->auth_user_request);
            snprintf(loginbuf, sizeof(loginbuf), "%s%s", username, orig_request->peer_login + 1);
            httpHeaderPutStrf(hdr_out, HDR_PROXY_AUTHORIZATION, "Basic %s",
                base64_encode(loginbuf));
        } else {
            httpHeaderPutStrf(hdr_out, HDR_PROXY_AUTHORIZATION, "Basic %s",
                base64_encode(orig_request->peer_login));
        }
    }
    /* append Cache-Control, add max-age if not there already */
    {
        HttpHdrCc *cc = httpHeaderGetCc(hdr_in);
        if (!cc)
            cc = httpHdrCcCreate();
        if (!EBIT_TEST(cc->mask, CC_MAX_AGE)) {
            const char *url = entry ? storeUrl(entry) : urlCanonical(orig_request);
            httpHdrCcSetMaxAge(cc, getMaxAge(url));
            if (strLen(request->urlpath))
                assert(strstr(url, strBuf(request->urlpath)));
        }
        if (flags.only_if_cached)
            EBIT_SET(cc->mask, CC_ONLY_IF_CACHED);
        httpHeaderPutCc(hdr_out, cc);
        httpHdrCcDestroy(cc);
    }
    /* maybe append Connection: keep-alive */
    if (flags.keepalive) {
        if (flags.proxying) {
            httpHeaderPutStr(hdr_out, HDR_PROXY_CONNECTION, "keep-alive");
        } else {
            httpHeaderPutStr(hdr_out, HDR_CONNECTION, "keep-alive");
        }
    }
    /* Now mangle the headers. */
    httpHdrMangleList(hdr_out, request);
    stringClean(&strConnection);
}

/* build request prefix and append it to a given MemBuf; 
 * return the length of the prefix */
mb_size_t
httpBuildRequestPrefix(request_t * request,
    request_t * orig_request,
    StoreEntry * entry,
    MemBuf * mb,
    int cfd,
    http_state_flags flags)
{
    const int offset = mb->size;
    memBufPrintf(mb, "%s %s HTTP/1.0\r\n",
        RequestMethodStr[request->method],
        strLen(request->urlpath) ? strBuf(request->urlpath) : "/");
    /* build and pack headers */
    {
        HttpHeader hdr;
        Packer p;
        httpBuildRequestHeader(request, orig_request, entry, &hdr, cfd, flags);
        packerToMemInit(&p, mb);
        httpHeaderPackInto(&hdr, &p);
        httpHeaderClean(&hdr);
        packerClean(&p);
    }
    /* append header terminator */
    memBufAppend(mb, crlf, 2);
    return mb->size - offset;
}
/* This will be called when connect completes. Write request. */
static void
httpSendRequest(HttpStateData * httpState)
{
    MemBuf mb;
    request_t *req = httpState->request;
    StoreEntry *entry = httpState->entry;
    int cfd;
    peer *p = httpState->peer;
    CWCB *sendHeaderDone;

    debug(11, 5) ("httpSendRequest: FD %d: httpState %p.\n", httpState->fd, httpState);

    if (httpState->orig_request->body_connection)
        sendHeaderDone = httpSendRequestEntry;
    else
        sendHeaderDone = httpSendComplete;

    if (!opt_forwarded_for)
        cfd = -1;
    else if (entry->mem_obj == NULL)
        cfd = -1;
    else
        cfd = entry->mem_obj->fd;
    assert(-1 == cfd || FD_SOCKET == fd_table[cfd].type);
    if (p != NULL)
        httpState->flags.proxying = 1;
    else
        httpState->flags.proxying = 0;
    /*
     * Is keep-alive okay for all request methods?
     */
    if (!Config.onoff.server_pconns)
        httpState->flags.keepalive = 0;
    else if (p == NULL)
        httpState->flags.keepalive = 1;
    else if (p->stats.n_keepalives_sent < 10)
        httpState->flags.keepalive = 1;
    else if ((double) p->stats.n_keepalives_recv / (double) p->stats.n_keepalives_sent > 0.50)
        httpState->flags.keepalive = 1;
    if (httpState->peer)
        if (neighborType(httpState->peer, httpState->request) == PEER_SIBLING &&
            !httpState->peer->options.allow_miss)
            httpState->flags.only_if_cached = 1;
    memBufDefInit(&mb);
    httpBuildRequestPrefix(req,
        httpState->orig_request,
        entry,
        &mb,
        cfd,
        httpState->flags);
    debug(11, 6) ("httpSendRequest: FD %d:\n%s\n", httpState->fd, mb.buf);
    comm_write_mbuf(httpState->fd, mb, sendHeaderDone, httpState);
}

void
httpStart(FwdState * fwd)
{
    int fd = fwd->server_fd;
    HttpStateData *httpState;
    request_t *proxy_req;
    request_t *orig_req = fwd->request;
    debug(11, 3) ("httpStart: \"%s %s\"\n",
        RequestMethodStr[orig_req->method],
        storeUrl(fwd->entry));
    httpState = CBDATA_ALLOC(HttpStateData, NULL);
    storeLockObject(fwd->entry);
    httpState->fwd = fwd;
    httpState->entry = fwd->entry;
    httpState->fd = fd;
    if (fwd->servers)
        httpState->peer = fwd->servers->peer;   /* might be NULL */
    if (httpState->peer) {
        proxy_req = requestCreate(orig_req->method,
            PROTO_NONE, storeUrl(httpState->entry));
        xstrncpy(proxy_req->host, httpState->peer->host, SQUIDHOSTNAMELEN);
        proxy_req->port = httpState->peer->http_port;
        proxy_req->flags = orig_req->flags;
        proxy_req->lastmod = orig_req->lastmod;
        httpState->request = requestLink(proxy_req);
        httpState->orig_request = requestLink(orig_req);
        proxy_req->flags.proxying = 1;
        /*
         * This NEIGHBOR_PROXY_ONLY check probably shouldn't be here.
         * We might end up getting the object from somewhere else if,
         * for example, the request to this neighbor fails.
         */
        if (httpState->peer->options.proxy_only)
            storeReleaseRequest(httpState->entry);
#if DELAY_POOLS
        assert(delayIsNoDelay(fd) == 0);
        if (httpState->peer->options.no_delay)
            delaySetNoDelay(fd);
#endif
    } else {
        httpState->request = requestLink(orig_req);
        httpState->orig_request = requestLink(orig_req);
    }
    /*
     * register the handler to free HTTP state data when the FD closes
     */
    comm_add_close_handler(fd, httpStateFree, httpState);
    statCounter.server.all.requests++;
    statCounter.server.http.requests++;
    httpSendRequest(httpState);
    /*
     * We used to set the read timeout here, but not any more.
     * Now its set in httpSendComplete() after the full request,
     * including request body, has been written to the server.
     */
}

static void
httpSendRequestEntryDone(int fd, void *data)
{
    HttpStateData *httpState = data;
    aclCheck_t ch;
    debug(11, 5) ("httpSendRequestEntryDone: FD %d\n",
        fd);
    memset(&ch, '\0', sizeof(ch));
    ch.request = httpState->request;
    if (!Config.accessList.brokenPosts) {
        debug(11, 5) ("httpSendRequestEntryDone: No brokenPosts list\n");
        httpSendComplete(fd, NULL, 0, 0, data);
    } else if (!aclCheckFast(Config.accessList.brokenPosts, &ch)) {
        debug(11, 5) ("httpSendRequestEntryDone: didn't match brokenPosts\n");
        httpSendComplete(fd, NULL, 0, 0, data);
    } else {
        debug(11, 2) ("httpSendRequestEntryDone: matched brokenPosts\n");
        comm_write(fd, "\r\n", 2, httpSendComplete, data, NULL);
    }
}

static void
httpRequestBodyHandler(char *buf, size_t size, void *data)
{
    HttpStateData *httpState = (HttpStateData *) data;
    if (size > 0) {
        comm_write(httpState->fd, buf, size, httpSendRequestEntry, data, memFree8K);
    } else if (size == 0) {
        /* End of body */
        memFree8K(buf);
        httpSendRequestEntryDone(httpState->fd, data);
    } else {
        /* Failed to get whole body, probably aborted */
        memFree8K(buf);
        httpSendComplete(httpState->fd, NULL, 0, COMM_ERR_CLOSING, data);
    }
}

static void
httpSendRequestEntry(int fd, char *bufnotused, size_t size, int errflag, void *data)
{
    HttpStateData *httpState = data;
    StoreEntry *entry = httpState->entry;
    ErrorState *err;
    debug(11, 5) ("httpSendRequestEntry: FD %d: size %d: errflag %d.\n",
        fd, size, errflag);
    if (size > 0) {
        fd_bytes(fd, size, FD_WRITE);
        kb_incr(&statCounter.server.all.kbytes_out, size);
        kb_incr(&statCounter.server.http.kbytes_out, size);
    }
    if (errflag == COMM_ERR_CLOSING)
        return;
    if (errflag) {
        err = errorCon(ERR_WRITE_ERROR, HTTP_INTERNAL_SERVER_ERROR);
        err->xerrno = errno;
        err->request = requestLink(httpState->orig_request);
        errorAppendEntry(entry, err);
        comm_close(fd);
        return;
    }
    if (EBIT_TEST(entry->flags, ENTRY_ABORTED)) {
        comm_close(fd);
        return;
    }
    clientReadBody(httpState->orig_request, memAllocate(MEM_8K_BUF), 8192, httpRequestBodyHandler, httpState);
}

void
httpBuildVersion(http_version_t * version, unsigned int major, unsigned int minor)
{
    version->major = major;
    version->minor = minor;
}