/*      $NetBSD: xsyslog.c,v 1.7 2020/03/02 15:30:25 christos Exp $     */

/*
* Copyright (c) 1983, 1988, 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. 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.
*/

#include <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
#if 0
static char sccsid[] = "@(#)syslog.c    8.5 (Berkeley) 4/29/95";
#else
__RCSID("$NetBSD: xsyslog.c,v 1.7 2020/03/02 15:30:25 christos Exp $");
#endif
#endif /* LIBC_SCCS and not lint */

#include "namespace.h"
#include <sys/types.h>
#include <sys/param.h>
#include <sys/socket.h>
#include <sys/syslog.h>
#include <sys/uio.h>
#include <sys/un.h>

#include <errno.h>
#include <stdio.h>
#include <stdarg.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <paths.h>
#include "syslog_private.h"
#include "reentrant.h"
#include "extern.h"

static void
disconnectlog_r(struct syslog_data *data)
{
       /*
        * If the user closed the FD and opened another in the same slot,
        * that's their problem.  They should close it before calling on
        * system services.
        */
       if (data->log_file != -1) {
               (void)close(data->log_file);
               data->log_file = -1;
       }
       data->log_connected = 0;                /* retry connect */
}

static void
connectlog_r(struct syslog_data *data)
{
       /* AF_UNIX address of local logger */
       static const struct sockaddr_un sun = {
               .sun_family = AF_LOCAL,
               .sun_len = sizeof(sun),
               .sun_path = _PATH_LOG,
       };

       if (data->log_file == -1 || fcntl(data->log_file, F_GETFL, 0) == -1) {
               if ((data->log_file = socket(AF_UNIX, SOCK_DGRAM | SOCK_CLOEXEC,
                   0)) == -1)
                       return;
               data->log_connected = 0;
       }
       if (!data->log_connected) {
               if (connect(data->log_file,
                   (const struct sockaddr *)(const void *)&sun,
                   (socklen_t)sizeof(sun)) == -1) {
                       (void)close(data->log_file);
                       data->log_file = -1;
               } else
                       data->log_connected = 1;
       }
}

void
_openlog_unlocked_r(const char *ident, int logstat, int logfac,
   struct syslog_data *data)
{
       if (ident != NULL)
               data->log_tag = ident;
       data->log_stat = logstat;
       if (logfac != 0 && (logfac &~ LOG_FACMASK) == 0)
               data->log_fac = logfac;

       if (data->log_stat & LOG_NDELAY)        /* open immediately */
               connectlog_r(data);

       data->log_opened = 1;
}

void
_closelog_unlocked_r(struct syslog_data *data)
{
       (void)close(data->log_file);
       data->log_file = -1;
       data->log_connected = 0;
}

static __sysloglike(6, 7) void
_xsyslogp_r(int pri, struct syslog_fun *fun,
   struct syslog_data *data, const char *msgid,
   const char *sdfmt, const char *msgfmt, ...)
{
       va_list ap;
       va_start(ap, msgfmt);
       _vxsyslogp_r(pri, fun, data, msgid, sdfmt, msgfmt, ap);
       va_end(ap);
}

void
_vxsyslogp_r(int pri, struct syslog_fun *fun,
   struct syslog_data *data, const char *msgid,
   const char *sdfmt, const char *msgfmt, va_list ap)
{
       static const char BRCOSP[] = "]: ";
       static const char CRLF[] = "\r\n";
       size_t cnt, prlen, tries;
       char ch, *p, *t;
       int fd, saved_errno;
#define TBUF_LEN        2048
#define FMT_LEN         1024
#define MAXTRIES        10
       char tbuf[TBUF_LEN], fmt_cpy[FMT_LEN], fmt_cat[FMT_LEN] = "";
       size_t tbuf_left, fmt_left, msgsdlen;
       char *fmt = fmt_cat;
       struct iovec iov[7];    /* prog + [ + pid + ]: + fmt + crlf */
       int opened, iovcnt;

       iovcnt = opened = 0;

#define INTERNALLOG     LOG_ERR|LOG_CONS|LOG_PERROR|LOG_PID
       /* Check for invalid bits. */
       if (pri & ~(LOG_PRIMASK|LOG_FACMASK)) {
               _xsyslogp_r(INTERNALLOG, &_syslog_ss_fun, data, NULL, NULL,
                   "Unknown facility/priority: %#x", pri);
               pri &= LOG_PRIMASK|LOG_FACMASK;
       }

       /* Check priority against setlogmask values. */
       if (!(LOG_MASK(LOG_PRI(pri)) & data->log_mask))
               return;

       saved_errno = errno;

       /* Set default facility if none specified. */
       if ((pri & LOG_FACMASK) == 0)
               pri |= data->log_fac;

       /* Build the message. */
       p = tbuf;
       tbuf_left = TBUF_LEN;

       prlen = snprintf_ss(p, tbuf_left, "<%d>1 ", pri);
       DEC();

       prlen = (*fun->timefun)(p, tbuf_left);

       (*fun->lock)(data);

       if (data->log_hostname[0] == '\0' && gethostname(data->log_hostname,
           sizeof(data->log_hostname)) == -1) {
               /* can this really happen? */
               data->log_hostname[0] = '-';
               data->log_hostname[1] = '\0';
       }

       DEC();
       prlen = snprintf_ss(p, tbuf_left, " %s ", data->log_hostname);

       if (data->log_tag == NULL)
               data->log_tag = getprogname();

       DEC();
       prlen = snprintf_ss(p, tbuf_left, "%s ",
           data->log_tag ? data->log_tag : "-");

       (*fun->unlock)(data);

       if (data->log_stat & (LOG_PERROR|LOG_CONS)) {
               iov[iovcnt].iov_base = p;
               iov[iovcnt].iov_len = prlen - 1;
               iovcnt++;
       }
       DEC();

       if (data->log_stat & LOG_PID) {
               prlen = snprintf_ss(p, tbuf_left, "%d ", getpid());
               if (data->log_stat & (LOG_PERROR|LOG_CONS)) {
                       iov[iovcnt].iov_base = __UNCONST("[");
                       iov[iovcnt].iov_len = 1;
                       iovcnt++;
                       iov[iovcnt].iov_base = p;
                       iov[iovcnt].iov_len = prlen - 1;
                       iovcnt++;
                       iov[iovcnt].iov_base = __UNCONST(BRCOSP);
                       iov[iovcnt].iov_len = 3;
                       iovcnt++;
               }
       } else {
               prlen = snprintf_ss(p, tbuf_left, "- ");
               if (data->log_stat & (LOG_PERROR|LOG_CONS)) {
                       iov[iovcnt].iov_base = __UNCONST(BRCOSP + 1);
                       iov[iovcnt].iov_len = 2;
                       iovcnt++;
               }
       }
       DEC();

       /*
        * concat the format strings, then use one vsnprintf()
        */
       if (msgid != NULL && *msgid != '\0') {
               strlcat(fmt_cat, msgid, FMT_LEN);
               strlcat(fmt_cat, " ", FMT_LEN);
       } else
               strlcat(fmt_cat, "- ", FMT_LEN);

       if (sdfmt != NULL && *sdfmt != '\0') {
               strlcat(fmt_cat, sdfmt, FMT_LEN);
       } else
               strlcat(fmt_cat, "-", FMT_LEN);

       if (data->log_stat & (LOG_PERROR|LOG_CONS))
               msgsdlen = strlen(fmt_cat) + 1;
       else
               msgsdlen = 0;   /* XXX: GCC */

       if (msgfmt != NULL && *msgfmt != '\0') {
               strlcat(fmt_cat, " ", FMT_LEN);
               strlcat(fmt_cat, msgfmt, FMT_LEN);
       }

       /*
        * We wouldn't need this mess if printf handled %m, or if
        * strerror() had been invented before syslog().
        */
       for (t = fmt_cpy, fmt_left = FMT_LEN; (ch = *fmt) != '\0'; ++fmt) {
               if (ch == '%' && fmt[1] == 'm') {
                       char buf[256];

                       if ((*fun->errfun)(saved_errno, buf, sizeof(buf)) != 0)
                               prlen = snprintf_ss(t, fmt_left, "Error %d",
                                   saved_errno);
                       else
                               prlen = strlcpy(t, buf, fmt_left);
                       if (prlen >= fmt_left)
                               prlen = fmt_left - 1;
                       t += prlen;
                       fmt++;
                       fmt_left -= prlen;
               } else if (ch == '%' && fmt[1] == '%' && fmt_left > 2) {
                       *t++ = '%';
                       *t++ = '%';
                       fmt++;
                       fmt_left -= 2;
               } else {
                       if (fmt_left > 1) {
                               *t++ = ch;
                               fmt_left--;
                       }
               }
       }
       *t = '\0';

       prlen = (*fun->prfun)(p, tbuf_left, fmt_cpy, ap);
       if (data->log_stat & (LOG_PERROR|LOG_CONS)) {
               iov[iovcnt].iov_base = p + msgsdlen;
               iov[iovcnt].iov_len = prlen - msgsdlen;
               iovcnt++;
       }

       DEC();
       cnt = p - tbuf;

       /* Output to stderr if requested. */
       if (data->log_stat & LOG_PERROR) {
               struct iovec *piov;
               int piovcnt;

               iov[iovcnt].iov_base = __UNCONST(CRLF + 1);
               iov[iovcnt].iov_len = 1;
               if (data->log_stat & LOG_PTRIM) {
                       piov = &iov[iovcnt - 1];
                       piovcnt = 2;
               } else {
                       piov = iov;
                       piovcnt = iovcnt + 1;
               }
               (void)writev(STDERR_FILENO, piov, piovcnt);
       }

       if (data->log_stat & LOG_NLOG)
               goto out;

       /* Get connected, output the message to the local logger. */
       (*fun->lock)(data);
       opened = !data->log_opened;
       if (opened)
               _openlog_unlocked_r(data->log_tag, data->log_stat, 0, data);
       connectlog_r(data);

       /*
        * If the send() failed, there are two likely scenarios:
        *  1) syslogd was restarted
        *  2) /dev/log is out of socket buffer space
        * We attempt to reconnect to /dev/log to take care of
        * case #1 and keep send()ing data to cover case #2
        * to give syslogd a chance to empty its socket buffer.
        */
       for (tries = 0; tries < MAXTRIES; tries++) {
               if (send(data->log_file, tbuf, cnt, 0) != -1)
                       break;
               if (errno != ENOBUFS) {
                       disconnectlog_r(data);
                       connectlog_r(data);
               } else
                       (void)usleep(1);
       }

       /*
        * Output the message to the console; try not to block
        * as a blocking console should not stop other processes.
        * Make sure the error reported is the one from the syslogd failure.
        */
       if (tries == MAXTRIES && (data->log_stat & LOG_CONS) &&
           (fd = open(_PATH_CONSOLE,
               O_WRONLY | O_NONBLOCK | O_CLOEXEC, 0)) >= 0) {
               iov[iovcnt].iov_base = __UNCONST(CRLF);
               iov[iovcnt].iov_len = 2;
               (void)writev(fd, iov, iovcnt + 1);
               (void)close(fd);
       }

out:
       if (!(*fun->unlock)(data) && opened)
               _closelog_unlocked_r(data);
}

int
setlogmask_r(int pmask, struct syslog_data *data)
{
       int omask;

       omask = data->log_mask;
       if (pmask != 0)
               data->log_mask = pmask;
       return omask;
}

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