logger: handle failures of gettimeofday()

[thirdparty/util-linux.git] / misc-utils / logger.c

/*
 * Copyright (c) 1983, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * 1999-02-22 Arkadiusz Miśkiewicz <misiek@pld.ORG.PL>
 * - added Native Language Support
 * Sun Mar 21 1999 - Arnaldo Carvalho de Melo <acme@conectiva.com.br>
 * - fixed strerr(errno) in gettext calls
 */

#include <errno.h>
#include <limits.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/time.h>
#include <stdio.h>
#include <ctype.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <getopt.h>
#include <pwd.h>
#include <signal.h>
#include <sys/uio.h>

#include "all-io.h"
#include "c.h"
#include "closestream.h"
#include "nls.h"
#include "pathnames.h"
#include "strutils.h"
#include "xalloc.h"
#include "strv.h"
#include "list.h"
#include "pwdutils.h"

#define SYSLOG_NAMES
#include <syslog.h>

#ifdef HAVE_LIBSYSTEMD
# define SD_JOURNAL_SUPPRESS_LOCATION
# include <systemd/sd-daemon.h>
# include <systemd/sd-journal.h>
#endif

#ifdef HAVE_SYS_TIMEX_H
# include <sys/timex.h>
#endif

enum {
        TYPE_UDP = (1 << 1),
        TYPE_TCP = (1 << 2),
        ALL_TYPES = TYPE_UDP | TYPE_TCP
};

enum {
        AF_UNIX_ERRORS_OFF = 0,
        AF_UNIX_ERRORS_ON,
        AF_UNIX_ERRORS_AUTO
};

enum {
        OPT_PRIO_PREFIX = CHAR_MAX + 1,
        OPT_JOURNALD,
        OPT_RFC3164,
        OPT_RFC5424,
        OPT_SOCKET_ERRORS,
        OPT_MSGID,
        OPT_NOACT,
        OPT_ID,
        OPT_STRUCTURED_DATA_ID,
        OPT_STRUCTURED_DATA_PARAM,
        OPT_OCTET_COUNT
};

/* rfc5424 structured data */
struct structured_data {
        char *id;               /* SD-ID */
        char **params;          /* array with SD-PARAMs */

        struct list_head        sds;
};

struct logger_ctl {
        int fd;
        int pri;
        pid_t pid;                      /* zero when unwanted */
        char *hdr;                      /* the syslog header (based on protocol) */
        char const *tag;
        char *login;
        char *msgid;
        char *unix_socket;              /* -u <path> or default to _PATH_DEVLOG */
        char *server;
        char *port;
        int socket_type;
        size_t max_message_size;
        struct list_head user_sds;      /* user defined rfc5424 structured data */
        struct list_head reserved_sds;  /* standard rfc5424 structured data */

        void (*syslogfp)(struct logger_ctl *ctl);

        unsigned int
                        unix_socket_errors:1,   /* whether to report or not errors */
                        noact:1,                /* do not write to sockets */
                        prio_prefix:1,          /* read priority from input */
                        stderr_printout:1,      /* output message to stderr */
                        rfc5424_time:1,         /* include time stamp */
                        rfc5424_tq:1,           /* include time quality markup */
                        rfc5424_host:1,         /* include hostname */
                        skip_empty_lines:1,     /* do not send empty lines when processing files */
                        octet_count:1;          /* use RFC6587 octet counting */
};

#define is_connected(_ctl)      ((_ctl)->fd >= 0)
static void logger_reopen(struct logger_ctl *ctl);

/*
 * For tests we want to be able to control datetime outputs
 */
#ifdef TEST_LOGGER
static inline int logger_gettimeofday(struct timeval *tv, struct timezone *tz)
{
        char *str = getenv("LOGGER_TEST_TIMEOFDAY");
        uintmax_t sec, usec;

        if (str && sscanf(str, "%ju.%ju", &sec, &usec) == 2) {
                tv->tv_sec = sec;
                tv->tv_usec = usec;
                return tv->tv_sec >= 0 && tv->tv_usec >= 0 ? 0 : -EINVAL;
        }

        return gettimeofday(tv, tz);
}

static inline char *logger_xgethostname(void)
{
        char *str = getenv("LOGGER_TEST_HOSTNAME");
        return str ? xstrdup(str) : xgethostname();
}

static inline pid_t logger_getpid(void)
{
        char *str = getenv("LOGGER_TEST_GETPID");
        unsigned int pid;

        if (str && sscanf(str, "%u", &pid) == 1)
                return pid;
        return getpid();
}


#undef HAVE_NTP_GETTIME         /* force to default non-NTP */

#else /* !TEST_LOGGER */
# define logger_gettimeofday(x, y)      gettimeofday(x, y)
# define logger_xgethostname            xgethostname
# define logger_getpid                  getpid
#endif


static int decode(const char *name, const CODE *codetab)
{
        register const CODE *c;

        if (name == NULL || *name == '\0')
                return -1;
        if (isdigit(*name)) {
                int num;
                char *end = NULL;

                errno = 0;
                num = strtol(name, &end, 10);
                if (errno || name == end || (end && *end))
                        return -1;
                for (c = codetab; c->c_name; c++)
                        if (num == c->c_val)
                                return num;
                return -1;
        }
        for (c = codetab; c->c_name; c++)
                if (!strcasecmp(name, c->c_name))
                        return (c->c_val);

        return -1;
}

static int pencode(char *s)
{
        int facility, level;
        char *separator;

        assert(s);

        separator = strchr(s, '.');
        if (separator) {
                *separator = '\0';
                facility = decode(s, facilitynames);
                if (facility < 0)
                        errx(EXIT_FAILURE, _("unknown facility name: %s"), s);
                s = ++separator;
        } else
                facility = LOG_USER;
        level = decode(s, prioritynames);
        if (level < 0)
                errx(EXIT_FAILURE, _("unknown priority name: %s"), s);
        if (facility == LOG_KERN)
                facility = LOG_USER;    /* kern is forbidden */
        return ((level & LOG_PRIMASK) | (facility & LOG_FACMASK));
}

static int unix_socket(struct logger_ctl *ctl, const char *path, int *socket_type)
{
        int fd = -1, i, type = -1;
        static struct sockaddr_un s_addr;       /* AF_UNIX address of local logger */

        if (strlen(path) >= sizeof(s_addr.sun_path))
                errx(EXIT_FAILURE, _("openlog %s: pathname too long"), path);

        s_addr.sun_family = AF_UNIX;
        xstrncpy(s_addr.sun_path, path, sizeof(s_addr.sun_path));

        for (i = 2; i; i--) {
                int st = -1;

                if (i == 2 && *socket_type & TYPE_UDP) {
                        st = SOCK_DGRAM;
                        type = TYPE_UDP;
                }
                if (i == 1 && *socket_type & TYPE_TCP) {
                        st = SOCK_STREAM;
                        type = TYPE_TCP;
                }
                if (st == -1 || (fd = socket(AF_UNIX, st, 0)) == -1)
                        continue;
                if (connect(fd, (struct sockaddr *)&s_addr, sizeof(s_addr)) == -1) {
                        close(fd);
                        continue;
                }
                break;
        }

        if (i == 0) {
                if (ctl->unix_socket_errors)
                        err(EXIT_FAILURE, _("socket %s"), path);

                /* write_output() will try to reconnect */
                return -1;
        }

        /* replace ALL_TYPES with the real TYPE_* */
        if (type > 0 && type != *socket_type)
                *socket_type = type;
        return fd;
}

static int inet_socket(const char *servername, const char *port, int *socket_type)
{
        int fd, errcode, i, type = -1;
        struct addrinfo hints, *res;
        const char *p = port;

        for (i = 2; i; i--) {
                memset(&hints, 0, sizeof(hints));
                if (i == 2 && *socket_type & TYPE_UDP) {
                        hints.ai_socktype = SOCK_DGRAM;
                        type = TYPE_UDP;
                        if (port == NULL)
                                p = "syslog";
                }
                if (i == 1 && *socket_type & TYPE_TCP) {
                        hints.ai_socktype = SOCK_STREAM;
                        type = TYPE_TCP;
                        if (port == NULL)
                                p = "syslog-conn";
                }
                if (hints.ai_socktype == 0)
                        continue;
                hints.ai_family = AF_UNSPEC;
                errcode = getaddrinfo(servername, p, &hints, &res);
                if (errcode != 0)
                        errx(EXIT_FAILURE, _("failed to resolve name %s port %s: %s"),
                             servername, p, gai_strerror(errcode));
                if ((fd = socket(res->ai_family, res->ai_socktype, res->ai_protocol)) == -1) {
                        freeaddrinfo(res);
                        continue;
                }
                if (connect(fd, res->ai_addr, res->ai_addrlen) == -1) {
                        freeaddrinfo(res);
                        close(fd);
                        continue;
                }

                freeaddrinfo(res);
                break;
        }

        if (i == 0)
                errx(EXIT_FAILURE, _("failed to connect to %s port %s"), servername, p);

        /* replace ALL_TYPES with the real TYPE_* */
        if (type > 0 && type != *socket_type)
                *socket_type = type;
        return fd;
}

#ifdef HAVE_LIBSYSTEMD
static int journald_entry(struct logger_ctl *ctl, FILE *fp)
{
        struct iovec *iovec;
        char *buf = NULL;
        ssize_t sz;
        int n, lines = 0, vectors = 8, ret = 0, msgline = -1;
        size_t dummy = 0;

        iovec = xreallocarray(NULL, vectors, sizeof(struct iovec));
        while (1) {
                buf = NULL;
                sz = getline(&buf, &dummy, fp);
                if (sz == -1 ||
                   (sz = rtrim_whitespace((unsigned char *) buf)) == 0) {
                        free(buf);
                        break;
                }

                if (strncmp(buf, "MESSAGE=", 8) == 0) {
                        if (msgline == -1)
                                msgline = lines;        /* remember the first message */
                        else {
                                char *p = xrealloc(iovec[msgline].iov_base,
                                                   iovec[msgline].iov_len + sz - 8 + 2);

                                iovec[msgline].iov_base = p;
                                p += iovec[msgline].iov_len;
                                *p++ = '\n';
                                memcpy(p, buf + 8, sz - 8);
                                free(buf);

                                iovec[msgline].iov_len += sz - 8 + 1;
                                continue;
                        }
                }

                if (lines == vectors) {
                        vectors *= 2;
                        if (IOV_MAX < vectors)
                                errx(EXIT_FAILURE, _("maximum input lines (%d) exceeded"), IOV_MAX);
                        iovec = xreallocarray(iovec, vectors, sizeof(struct iovec));
                }
                iovec[lines].iov_base = buf;
                iovec[lines].iov_len = sz;
                ++lines;
        }

        if (!ctl->noact)
                ret = sd_journal_sendv(iovec, lines);
        if (ctl->stderr_printout) {
                for (n = 0; n < lines; n++)
                        fprintf(stderr, "%s\n", (char *) iovec[n].iov_base);
        }
        for (n = 0; n < lines; n++)
                free(iovec[n].iov_base);
        free(iovec);
        return ret;
}
#endif

/* this creates a timestamp based on current time according to the
 * fine rules of RFC3164, most importantly it ensures in a portable
 * way that the month day is correctly written (with a SP instead
 * of a leading 0). The function uses a static buffer which is
 * overwritten on the next call (just like ctime() does).
 */
static char const *rfc3164_current_time(void)
{
        static char time[32];
        struct timeval tv;
        struct tm tm;
        int ret;
        static char const * const monthnames[] = {
                "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug",
                "Sep", "Oct", "Nov", "Dec"
        };

        ret = logger_gettimeofday(&tv, NULL);
        if (ret == -1)
                err(EXIT_FAILURE, _("gettimeofday() failed"));
        localtime_r(&tv.tv_sec, &tm);
        snprintf(time, sizeof(time),"%s %2d %2.2d:%2.2d:%2.2d",
                monthnames[tm.tm_mon], tm.tm_mday,
                tm.tm_hour, tm.tm_min, tm.tm_sec);
        return time;
}

#define next_iovec(ary, idx) __extension__ ({           \
                assert(ARRAY_SIZE(ary) > (size_t)idx);  \
                assert(idx >= 0);                       \
                &ary[idx++];                            \
})

#define iovec_add_string(ary, idx, str, len)            \
        do {                                            \
                struct iovec *v = next_iovec(ary, idx); \
                v->iov_base = (void *) str;             \
                v->iov_len = len ? len : strlen(str);   \
        } while (0)

#define iovec_memcmp(ary, idx, str, len)                \
                memcmp((ary)[(idx) - 1].iov_base, str, len)

/* writes generated buffer to desired destination. For TCP syslog,
 * we use RFC6587 octet-stuffing (unless octet-counting is selected).
 * This is not great, but doing full blown RFC5425 (TLS) looks like
 * it is too much for the logger utility. If octet-counting is
 * selected, we use that.
 */
static void write_output(struct logger_ctl *ctl, const char *const msg)
{
        struct iovec iov[4];
        int iovlen = 0;
        char *octet = NULL;

        /* initial connect failed? */
        if (!ctl->noact && !is_connected(ctl))
                logger_reopen(ctl);

        /* 1) octet count */
        if (ctl->octet_count) {
                size_t len = xasprintf(&octet, "%zu ", strlen(ctl->hdr) + strlen(msg));
                iovec_add_string(iov, iovlen, octet, len);
        }

        /* 2) header */
        iovec_add_string(iov, iovlen, ctl->hdr, 0);

        /* 3) message */
        iovec_add_string(iov, iovlen, msg, 0);

        if (!ctl->noact && is_connected(ctl)) {
                struct msghdr message = { 0 };
#ifdef SCM_CREDENTIALS
                struct cmsghdr *cmhp;
                struct ucred *cred;
                union {
                        struct cmsghdr cmh;
                        char   control[CMSG_SPACE(sizeof(struct ucred))];
                } cbuf = { .control = { 0 } };
#endif

                /* 4) add extra \n to make sure message is terminated */
                if ((ctl->socket_type == TYPE_TCP) && !ctl->octet_count)
                        iovec_add_string(iov, iovlen, "\n", 1);

                message.msg_iov = iov;
                message.msg_iovlen = iovlen;

#ifdef SCM_CREDENTIALS
                /* syslog/journald may follow local socket credentials rather
                 * than in the message PID. If we use --id as root than we can
                 * force kernel to accept another valid PID than the real logger(1)
                 * PID.
                 */
                if (ctl->pid && !ctl->server && ctl->pid != getpid()
                    && geteuid() == 0 && kill(ctl->pid, 0) == 0) {

                        message.msg_control = cbuf.control;
                        message.msg_controllen = CMSG_SPACE(sizeof(struct ucred));

                        cmhp = CMSG_FIRSTHDR(&message);
                        cmhp->cmsg_len = CMSG_LEN(sizeof(struct ucred));
                        cmhp->cmsg_level = SOL_SOCKET;
                        cmhp->cmsg_type = SCM_CREDENTIALS;
                        cred = (struct ucred *) CMSG_DATA(cmhp);

                        cred->pid = ctl->pid;
                }
#endif
                /* Note that logger(1) maybe executed for long time (as pipe
                 * reader) and connection endpoint (syslogd) may be restarted.
                 *
                 * The libc syslog() function reconnects on failed send().
                 * Let's do the same to be robust.    [kzak -- Oct 2017]
                 *
                 * MSG_NOSIGNAL is POSIX.1-2008 compatible, but it for example
                 * not supported by apple-darwin15.6.0.
                 */
#ifndef MSG_NOSIGNAL
# define MSG_NOSIGNAL 0
#endif
                if (sendmsg(ctl->fd, &message, MSG_NOSIGNAL) < 0) {
                        logger_reopen(ctl);
                        if (sendmsg(ctl->fd, &message, MSG_NOSIGNAL) < 0)
                                warn(_("send message failed"));
                }
        }

        if (ctl->stderr_printout) {
                /* make sure it's terminated for stderr */
                if (iovec_memcmp(iov, iovlen, "\n", 1) != 0)
                        iovec_add_string(iov, iovlen, "\n", 1);

                ignore_result( writev(STDERR_FILENO, iov, iovlen) );
        }

        free(octet);
}

#define NILVALUE "-"
static void syslog_rfc3164_header(struct logger_ctl *const ctl)
{
        char pid[30], *hostname;

        *pid = '\0';
        if (ctl->pid)
                snprintf(pid, sizeof(pid), "[%d]", ctl->pid);

        if ((hostname = logger_xgethostname())) {
                char *dot = strchr(hostname, '.');
                if (dot)
                        *dot = '\0';
        } else
                hostname = xstrdup(NILVALUE);

        xasprintf(&ctl->hdr, "<%d>%.15s %s %.200s%s: ",
                 ctl->pri, rfc3164_current_time(), hostname, ctl->tag, pid);

        free(hostname);
}

static inline struct list_head *get_user_structured_data(struct logger_ctl *ctl)
{
        return &ctl->user_sds;
}

static inline struct list_head *get_reserved_structured_data(struct logger_ctl *ctl)
{
        return &ctl->reserved_sds;
}

static int has_structured_data_id(struct list_head *ls, const char *id)
{
        struct list_head *p;

        if (!ls || list_empty(ls))
                return 0;

        list_for_each(p, ls) {
                struct structured_data *sd = list_entry(p, struct structured_data, sds);
                if (sd->id && strcmp(sd->id, id) == 0)
                        return 1;
        }

        return 0;
}

static void add_structured_data_id(struct list_head *ls, const char *id)
{
        struct structured_data *sd;

        assert(id);

        if (has_structured_data_id(ls, id))
                errx(EXIT_FAILURE, _("structured data ID '%s' is not unique"), id);

        sd = xcalloc(1, sizeof(*sd));
        INIT_LIST_HEAD(&sd->sds);
        sd->id = xstrdup(id);

        list_add_tail(&sd->sds, ls);
}

static void add_structured_data_param(struct list_head *ls, const char *param)
{
        struct structured_data *sd;

        if (list_empty(ls))
                errx(EXIT_FAILURE, _("--sd-id was not specified for --sd-param %s"), param);

        assert(param);

        sd = list_last_entry(ls, struct structured_data, sds);

        if (strv_extend(&sd->params,  param))
                err_oom();
}

static void __attribute__ ((__format__ (__printf__, 2, 3)))
        add_structured_data_paramf(struct list_head *ls, const char *fmt, ...)
{
        struct structured_data *sd;
        va_list ap;
        int x;

        assert(!list_empty(ls));
        assert(fmt);

        sd = list_last_entry(ls, struct structured_data, sds);
        va_start(ap, fmt);
        x = strv_extendv(&sd->params, fmt, ap);
        va_end(ap);

        if (x)
                err_oom();
}

static char *strdup_structured_data(struct structured_data *sd)
{
        char *res, *tmp;

        if (strv_isempty(sd->params))
                return NULL;

        xasprintf(&res, "[%s %s]", sd->id,
                        (tmp = strv_join(sd->params, " ")));
        free(tmp);
        return res;
}

static char *strdup_structured_data_list(struct list_head *ls)
{
        struct list_head *p;
        char *res = NULL;

        list_for_each(p, ls) {
                struct structured_data *sd = list_entry(p, struct structured_data, sds);
                char *one = strdup_structured_data(sd);
                char *tmp = res;

                if (!one)
                        continue;
                res = strconcat(tmp, one);
                free(tmp);
                free(one);
        }

        return res;
}

static char *get_structured_data_string(struct logger_ctl *ctl)
{
        char *sys = NULL, *usr = NULL, *res;

        if (!list_empty(&ctl->reserved_sds))
                sys = strdup_structured_data_list(&ctl->reserved_sds);
        if (!list_empty(&ctl->user_sds))
                usr = strdup_structured_data_list(&ctl->user_sds);

        if (sys && usr) {
                res = strconcat(sys, usr);
                free(sys);
                free(usr);
        } else
                res = sys ? sys : usr;

        return res;
}

static int valid_structured_data_param(const char *str)
{
        char *s;
        char *eq  = strchr(str, '='),
             *qm1 = strchr(str, '"'),
             *qm2 = qm1 ? ul_strchr_escaped(qm1 + 1, '"') : NULL;

        /* something is missing */
        if (!eq || !qm1 || !qm2)
                return 0;

        /* ']' need to be escaped */
        for (s = qm1 + 1; s && *s; ) {
                char *p = strchr(s, ']');
                if (!p)
                        break;
                if (p > qm2 || p == ul_strchr_escaped(s, ']'))
                        return 0;
                s = p + 1;
        }

        /* '\' is allowed only before '[]"\' chars */
        for (s = qm1 + 1; s && *s; ) {
                char *p = strchr(s, '\\');
                if (!p)
                        break;
                if (!strchr("[]\"\\", *(p + 1)))
                        return 0;
                s = p + 1;
                if (*s == '\\')
                        s++;
        }

        /* foo="bar" */
        return eq > str && eq < qm1 && eq + 1 == qm1 && qm1 < qm2 && *(qm2 + 1) == '\0';
}

/* SD-ID format:
 *      name@<private enterprise number>, e.g., "ourSDID@32473"
 */
static int valid_structured_data_id(const char *str)
{
        char *at = strchr(str, '@');
        const char *p;

        /* standardized IDs without @<digits> */
        if (!at && (strcmp(str, "timeQuality") == 0 ||
                    strcmp(str, "origin") == 0 ||
                    strcmp(str, "meta") == 0))
                return 1;

        if (!at || at == str || !*(at + 1))
                return 0;

        /* <digits> or <digits>.<digits>[...] */
        for (p = at + 1; p && *p; p++) {
                const char *end;

                if (isdigit_strend(p, &end))
                        break;  /* only digits in the string */

                if (end == NULL || end == p ||
                    *end != '.' || *(end + 1) == '\0')
                        return 0;
                p = end;
        }

        /* check for forbidden chars in the <name> */
        for (p = str; p < at; p++) {
                if (*p == '[' || *p == '=' || *p == '"' || *p == '@')
                        return 0;
                if (isblank((unsigned char) *p) || iscntrl((unsigned char) *p))
                        return 0;
        }
        return 1;
}


/* Some field mappings may be controversial, thus I give the reason
 * why this specific mapping was used:
 * APP-NAME <-- tag
 *    Some may argue that "logger" is a better fit, but we think
 *    this is better inline of what other implementations do. In
 *    rsyslog, for example, the TAG value is populated from APP-NAME.
 * PROCID <-- pid
 *    This is a relatively straightforward interpretation from
 *    RFC5424, sect. 6.2.6.
 * MSGID <-- msgid (from --msgid)
 *    One may argue that the string "logger" would be better suited
 *    here so that a receiver can identify the sender process.
 *    However, this does not sound like a good match to RFC5424,
 *    sect. 6.2.7.
 * Note that appendix A.1 of RFC5424 does not provide clear guidance
 * of how these fields should be used. This is the case because the
 * IETF working group couldn't arrive at a clear agreement when we
 * specified RFC5424. The rest of the field mappings should be
 * pretty clear from RFC5424. -- Rainer Gerhards, 2015-03-10
 */
static void syslog_rfc5424_header(struct logger_ctl *const ctl)
{
        int ret;
        char *time;
        char *hostname;
        char const *app_name = ctl->tag;
        char *procid;
        char *const msgid = xstrdup(ctl->msgid ? ctl->msgid : NILVALUE);
        char *structured = NULL;
        struct list_head *sd;

        if (ctl->rfc5424_time) {
                struct timeval tv;
                struct tm tm;

                ret = logger_gettimeofday(&tv, NULL);
                if (ret == -1)
                        err(EXIT_FAILURE, _("gettimeofday() failed"));
                if (localtime_r(&tv.tv_sec, &tm) != NULL) {
                        char fmt[64];
                        const size_t i = strftime(fmt, sizeof(fmt),
                                                  "%Y-%m-%dT%H:%M:%S.%%06u%z ", &tm);
                        /* patch TZ info to comply with RFC3339 (we left SP at end) */
                        fmt[i - 1] = fmt[i - 2];
                        fmt[i - 2] = fmt[i - 3];
                        fmt[i - 3] = ':';
                        xasprintf(&time, fmt, tv.tv_usec);
                } else
                        err(EXIT_FAILURE, _("localtime() failed"));
        } else
                time = xstrdup(NILVALUE);

        if (ctl->rfc5424_host) {
                if (!(hostname = logger_xgethostname()))
                        hostname = xstrdup(NILVALUE);
                /* Arbitrary looking 'if (var < strlen()) checks originate from
                 * RFC 5424 - 6 Syslog Message Format definition.  */
                if (255 < strlen(hostname))
                        errx(EXIT_FAILURE, _("hostname '%s' is too long"),
                             hostname);
        } else
                hostname = xstrdup(NILVALUE);

        if (48 < strlen(ctl->tag))
                errx(EXIT_FAILURE, _("tag '%s' is too long"), ctl->tag);

        if (ctl->pid)
                xasprintf(&procid, "%d", ctl->pid);
        else
                procid = xstrdup(NILVALUE);

        sd = get_reserved_structured_data(ctl);

        /* time quality structured data (maybe overwritten by --sd-id timeQuality) */
        if (ctl->rfc5424_tq && !has_structured_data_id(sd, "timeQuality")) {

                add_structured_data_id(sd, "timeQuality");
                add_structured_data_param(sd, "tzKnown=\"1\"");

#ifdef HAVE_NTP_GETTIME
                struct ntptimeval ntptv;

                if (ntp_gettime(&ntptv) == TIME_OK) {
                        add_structured_data_param(sd, "isSynced=\"1\"");
                        add_structured_data_paramf(sd, "syncAccuracy=\"%ld\"", ntptv.maxerror);
                } else
#endif
                        add_structured_data_paramf(sd, "isSynced=\"0\"");
        }

        /* convert all structured data to string */
        structured = get_structured_data_string(ctl);
        if (!structured)
                structured = xstrdup(NILVALUE);

        xasprintf(&ctl->hdr, "<%d>1 %s %s %s %s %s %s ",
                ctl->pri,
                time,
                hostname,
                app_name,
                procid,
                msgid,
                structured);

        free(time);
        free(hostname);
        /* app_name points to ctl->tag, do NOT free! */
        free(procid);
        free(msgid);
        free(structured);
}

static void parse_rfc5424_flags(struct logger_ctl *ctl, char *s)
{
        char *in, *tok;

        in = s;
        while ((tok = strtok(in, ","))) {
                in = NULL;
                if (!strcmp(tok, "notime")) {
                        ctl->rfc5424_time = 0;
                        ctl->rfc5424_tq = 0;
                } else if (!strcmp(tok, "notq"))
                        ctl->rfc5424_tq = 0;
                else if (!strcmp(tok, "nohost"))
                        ctl->rfc5424_host = 0;
                else
                        warnx(_("ignoring unknown option argument: %s"), tok);
        }
}

static int parse_unix_socket_errors_flags(char *s)
{
        if (!strcmp(s, "off"))
                return AF_UNIX_ERRORS_OFF;
        if (!strcmp(s, "on"))
                return AF_UNIX_ERRORS_ON;
        if (!strcmp(s, "auto"))
                return AF_UNIX_ERRORS_AUTO;
        warnx(_("invalid argument: %s: using automatic errors"), s);
        return AF_UNIX_ERRORS_AUTO;
}

static void syslog_local_header(struct logger_ctl *const ctl)
{
        char pid[32];

        if (ctl->pid)
                snprintf(pid, sizeof(pid), "[%d]", ctl->pid);
        else
                pid[0] = '\0';

        xasprintf(&ctl->hdr, "<%d>%s %s%s: ", ctl->pri, rfc3164_current_time(),
                ctl->tag, pid);
}

static void generate_syslog_header(struct logger_ctl *const ctl)
{
        free(ctl->hdr);
        ctl->hdr = NULL;
        ctl->syslogfp(ctl);
}

/* just open, nothing else */
static void __logger_open(struct logger_ctl *ctl)
{
        if (ctl->server) {
                ctl->fd = inet_socket(ctl->server, ctl->port, &ctl->socket_type);
        } else {
                if (!ctl->unix_socket)
                        ctl->unix_socket = _PATH_DEVLOG;

                ctl->fd = unix_socket(ctl, ctl->unix_socket, &ctl->socket_type);
        }
}

/* open and initialize relevant @ctl tuff */
static void logger_open(struct logger_ctl *ctl)
{
        __logger_open(ctl);

        if (!ctl->syslogfp)
                ctl->syslogfp = ctl->server ? syslog_rfc5424_header :
                                              syslog_local_header;
        if (!ctl->tag)
                ctl->tag = ctl->login = xgetlogin();
        if (!ctl->tag)
                ctl->tag = "<someone>";
}

/* re-open; usually after failed connection */
static void logger_reopen(struct logger_ctl *ctl)
{
        if (ctl->fd != -1)
                close(ctl->fd);
        ctl->fd = -1;

        __logger_open(ctl);
}

static void logger_command_line(struct logger_ctl *ctl, char **argv)
{
        /* note: we never re-generate the syslog header here, even if we
         * generate multiple messages. If so, we think it is the right thing
         * to do to report them with the same timestamp, as the user actually
         * intended to send a single message.
         */
        char *const buf = xmalloc(ctl->max_message_size + 1);
        char *p = buf;
        const char *endp = buf + ctl->max_message_size - 1;
        size_t len;

        while (*argv) {
                len = strlen(*argv);
                if (endp < p + len && p != buf) {
                        write_output(ctl, buf);
                        p = buf;
                }
                if (ctl->max_message_size < len) {
                        (*argv)[ctl->max_message_size] = '\0'; /* truncate */
                        write_output(ctl, *argv++);
                        continue;
                }
                if (p != buf)
                        *p++ = ' ';
                memmove(p, *argv++, len);
                *(p += len) = '\0';
        }
        if (p != buf)
                write_output(ctl, buf);
        free(buf);
}

static void logger_stdin(struct logger_ctl *ctl)
{
        /* note: we re-generate the syslog header for each log message to
         * update header timestamps and to reflect possible priority changes.
         */
        int default_priority = ctl->pri;
        char *buf = xmalloc(ctl->max_message_size + 2 + 2);
        int pri;
        int c;
        size_t i;

        c = getchar();
        while (c != EOF) {
                i = 0;
                if (ctl->prio_prefix && c == '<') {
                        pri = 0;
                        buf[i++] = c;
                        while (isdigit(c = getchar()) && pri <= 191) {
                                buf[i++] = c;
                                pri = pri * 10 + c - '0';
                        }
                        if (c != EOF && c != '\n')
                                buf[i++] = c;
                        if (c == '>' && 0 <= pri && pri <= 191) {
                                /* valid RFC PRI values */
                                i = 0;
                                if ((pri & LOG_FACMASK) == 0)
                                        pri |= (default_priority & LOG_FACMASK);
                                ctl->pri = pri;
                        } else
                                ctl->pri = default_priority;

                        if (c != EOF && c != '\n')
                                c = getchar();
                }

                while (c != EOF && c != '\n' && i < ctl->max_message_size) {
                        buf[i++] = c;
                        c = getchar();
                }
                buf[i] = '\0';

                if (i > 0 || !ctl->skip_empty_lines) {
                        generate_syslog_header(ctl);
                        write_output(ctl, buf);
                }

                if (c == '\n')  /* discard line terminator */
                        c = getchar();
        }

        free(buf);
}

static void logger_close(const struct logger_ctl *ctl)
{
        if (ctl->fd != -1 && close(ctl->fd) != 0)
                err(EXIT_FAILURE, _("close failed"));
        free(ctl->hdr);
        free(ctl->login);
}

static void __attribute__((__noreturn__)) usage(void)
{
        FILE *out = stdout;
        fputs(USAGE_HEADER, out);
        fprintf(out, _(" %s [options] [<message>]\n"), program_invocation_short_name);

        fputs(USAGE_SEPARATOR, out);
        fputs(_("Enter messages into the system log.\n"), out);

        fputs(USAGE_OPTIONS, out);
        fputs(_(" -i                       log the logger command's PID\n"), out);
        fputs(_("     --id[=<id>]          log the given <id>, or otherwise the PID\n"), out);
        fputs(_(" -f, --file <file>        log the contents of this file\n"), out);
        fputs(_(" -e, --skip-empty         do not log empty lines when processing files\n"), out);
        fputs(_("     --no-act             do everything except the write the log\n"), out);
        fputs(_(" -p, --priority <prio>    mark given message with this priority\n"), out);
        fputs(_("     --octet-count        use rfc6587 octet counting\n"), out);
        fputs(_("     --prio-prefix        look for a prefix on every line read from stdin\n"), out);
        fputs(_(" -s, --stderr             output message to standard error as well\n"), out);
        fputs(_(" -S, --size <size>        maximum size for a single message\n"), out);
        fputs(_(" -t, --tag <tag>          mark every line with this tag\n"), out);
        fputs(_(" -n, --server <name>      write to this remote syslog server\n"), out);
        fputs(_(" -P, --port <port>        use this port for UDP or TCP connection\n"), out);
        fputs(_(" -T, --tcp                use TCP only\n"), out);
        fputs(_(" -d, --udp                use UDP only\n"), out);
        fputs(_("     --rfc3164            use the obsolete BSD syslog protocol\n"), out);
        fputs(_("     --rfc5424[=<snip>]   use the syslog protocol (the default for remote);\n"
                "                            <snip> can be notime, or notq, and/or nohost\n"), out);
        fputs(_("     --sd-id <id>         rfc5424 structured data ID\n"), out);
        fputs(_("     --sd-param <data>    rfc5424 structured data name=value\n"), out);
        fputs(_("     --msgid <msgid>      set rfc5424 message id field\n"), out);
        fputs(_(" -u, --socket <socket>    write to this Unix socket\n"), out);
        fputs(_("     --socket-errors[=<on|off|auto>]\n"
                "                          print connection errors when using Unix sockets\n"), out);
#ifdef HAVE_LIBSYSTEMD
        fputs(_("     --journald[=<file>]  write journald entry\n"), out);
#endif

        fputs(USAGE_SEPARATOR, out);
        fprintf(out, USAGE_HELP_OPTIONS(26));
        fprintf(out, USAGE_MAN_TAIL("logger(1)"));

        exit(EXIT_SUCCESS);
}

/*
 * logger -- read and log utility
 *
 *      Reads from an input and arranges to write the result on the system
 *      log.
 */
int main(int argc, char **argv)
{
        struct logger_ctl ctl = {
                .fd = -1,
                .pid = 0,
                .pri = LOG_USER | LOG_NOTICE,
                .prio_prefix = 0,
                .tag = NULL,
                .unix_socket = NULL,
                .unix_socket_errors = 0,
                .server = NULL,
                .port = NULL,
                .hdr = NULL,
                .msgid = NULL,
                .socket_type = ALL_TYPES,
                .max_message_size = 1024,
                .rfc5424_time = 1,
                .rfc5424_tq = 1,
                .rfc5424_host = 1,
                .skip_empty_lines = 0
        };
        int ch;
        int stdout_reopened = 0;
        int unix_socket_errors_mode = AF_UNIX_ERRORS_AUTO;
#ifdef HAVE_LIBSYSTEMD
        FILE *jfd = NULL;
#endif
        static const struct option longopts[] = {
                { "id",            optional_argument, 0, OPT_ID            },
                { "stderr",        no_argument,       0, 's'               },
                { "file",          required_argument, 0, 'f'               },
                { "no-act",        no_argument,       0, OPT_NOACT,        },
                { "priority",      required_argument, 0, 'p'               },
                { "tag",           required_argument, 0, 't'               },
                { "socket",        required_argument, 0, 'u'               },
                { "socket-errors", required_argument, 0, OPT_SOCKET_ERRORS },
                { "udp",           no_argument,       0, 'd'               },
                { "tcp",           no_argument,       0, 'T'               },
                { "server",        required_argument, 0, 'n'               },
                { "port",          required_argument, 0, 'P'               },
                { "version",       no_argument,       0, 'V'               },
                { "help",          no_argument,       0, 'h'               },
                { "octet-count",   no_argument,       0, OPT_OCTET_COUNT   },
                { "prio-prefix",   no_argument,       0, OPT_PRIO_PREFIX   },
                { "rfc3164",       no_argument,       0, OPT_RFC3164       },
                { "rfc5424",       optional_argument, 0, OPT_RFC5424       },
                { "size",          required_argument, 0, 'S'               },
                { "msgid",         required_argument, 0, OPT_MSGID         },
                { "skip-empty",    no_argument,       0, 'e'               },
                { "sd-id",         required_argument, 0, OPT_STRUCTURED_DATA_ID          },
                { "sd-param",      required_argument, 0, OPT_STRUCTURED_DATA_PARAM       },
#ifdef HAVE_LIBSYSTEMD
                { "journald",      optional_argument, 0, OPT_JOURNALD      },
#endif
                { NULL,            0,                 0, 0                 }
        };

        setlocale(LC_ALL, "");
        bindtextdomain(PACKAGE, LOCALEDIR);
        textdomain(PACKAGE);
        close_stdout_atexit();

        INIT_LIST_HEAD(&ctl.user_sds);
        INIT_LIST_HEAD(&ctl.reserved_sds);

        while ((ch = getopt_long(argc, argv, "ef:ip:S:st:u:dTn:P:Vh",
                                            longopts, NULL)) != -1) {
                switch (ch) {
                case 'f':               /* file to log */
                        if (freopen(optarg, "r", stdin) == NULL)
                                err(EXIT_FAILURE, _("file %s"), optarg);
                        stdout_reopened = 1;
                        break;
                case 'e':
                        ctl.skip_empty_lines = 1;
                        break;
                case 'i':               /* log process id also */
                        ctl.pid = logger_getpid();
                        break;
                case OPT_ID:
                        if (optarg) {
                                const char *p = optarg;

                                if (*p == '=')
                                        p++;
                                ctl.pid = strtoul_or_err(optarg, _("failed to parse id"));
                        } else
                                ctl.pid = logger_getpid();
                        break;
                case 'p':               /* priority */
                        ctl.pri = pencode(optarg);
                        break;
                case 's':               /* log to standard error */
                        ctl.stderr_printout = 1;
                        break;
                case 't':               /* tag */
                        ctl.tag = optarg;
                        break;
                case 'u':               /* unix socket */
                        ctl.unix_socket = optarg;
                        break;
                case 'S':               /* max message size */
                        ctl.max_message_size = strtosize_or_err(optarg,
                                _("failed to parse message size"));
                        break;
                case 'd':
                        ctl.socket_type = TYPE_UDP;
                        break;
                case 'T':
                        ctl.socket_type = TYPE_TCP;
                        break;
                case 'n':
                        ctl.server = optarg;
                        break;
                case 'P':
                        ctl.port = optarg;
                        break;
                case OPT_OCTET_COUNT:
                        ctl.octet_count = 1;
                        break;
                case OPT_PRIO_PREFIX:
                        ctl.prio_prefix = 1;
                        break;
                case OPT_RFC3164:
                        ctl.syslogfp = syslog_rfc3164_header;
                        break;
                case OPT_RFC5424:
                        ctl.syslogfp = syslog_rfc5424_header;
                        if (optarg)
                                parse_rfc5424_flags(&ctl, optarg);
                        break;
                case OPT_MSGID:
                        if (strchr(optarg, ' '))
                                errx(EXIT_FAILURE, _("--msgid cannot contain space"));
                        ctl.msgid = optarg;
                        break;
#ifdef HAVE_LIBSYSTEMD
                case OPT_JOURNALD:
                        if (optarg) {
                                jfd = fopen(optarg, "r");
                                if (!jfd)
                                        err(EXIT_FAILURE, _("cannot open %s"),
                                            optarg);
                        } else
                                jfd = stdin;
                        break;
#endif
                case OPT_SOCKET_ERRORS:
                        unix_socket_errors_mode = parse_unix_socket_errors_flags(optarg);
                        break;
                case OPT_NOACT:
                        ctl.noact = 1;
                        break;
                case OPT_STRUCTURED_DATA_ID:
                        if (!valid_structured_data_id(optarg))
                                errx(EXIT_FAILURE, _("invalid structured data ID: '%s'"), optarg);
                        add_structured_data_id(get_user_structured_data(&ctl), optarg);
                        break;
                case OPT_STRUCTURED_DATA_PARAM:
                        if (!valid_structured_data_param(optarg))
                                errx(EXIT_FAILURE, _("invalid structured data parameter: '%s'"), optarg);
                        add_structured_data_param(get_user_structured_data(&ctl), optarg);
                        break;

                case 'V':
                        print_version(EXIT_SUCCESS);
                case 'h':
                        usage();
                default:
                        errtryhelp(EXIT_FAILURE);
                }
        }
        argc -= optind;
        argv += optind;
        if (stdout_reopened && argc)
                warnx(_("--file <file> and <message> are mutually exclusive, message is ignored"));
#ifdef HAVE_LIBSYSTEMD
        if (jfd) {
                int ret = journald_entry(&ctl, jfd);
                if (stdin != jfd)
                        fclose(jfd);
                if (ret)
                        errx(EXIT_FAILURE, _("journald entry could not be written"));
                return EXIT_SUCCESS;
        }
#endif

        /* user overwrites built-in SD-ELEMENT */
        if (has_structured_data_id(get_user_structured_data(&ctl), "timeQuality"))
                ctl.rfc5424_tq = 0;

        switch (unix_socket_errors_mode) {
        case AF_UNIX_ERRORS_OFF:
                ctl.unix_socket_errors = 0;
                break;
        case AF_UNIX_ERRORS_ON:
                ctl.unix_socket_errors = 1;
                break;
        case AF_UNIX_ERRORS_AUTO:
                ctl.unix_socket_errors = ctl.noact || ctl.stderr_printout;
#ifdef HAVE_LIBSYSTEMD
                ctl.unix_socket_errors |= !!sd_booted();
#endif
                break;
        default:
                abort();
        }
        logger_open(&ctl);
        if (0 < argc) {
                generate_syslog_header(&ctl);
                logger_command_line(&ctl, argv);
        } else
                /* Note. --file <arg> reopens stdin making the below
                 * function to be used for file inputs. */
                logger_stdin(&ctl);

        logger_close(&ctl);
        return EXIT_SUCCESS;
}