ap_lingerd.c

ap_lingerd.c (text/plain), 3.54 KB, created by Minati jean michel on 2004-09-27 12:57:55 UTC

/*
 * Copyright (C) 2000, iAgora LLC.
 * Written by Roger Espel Llima for iAgora LLC, 28-NOV-2000.
 *
 * This program is Free Software.  You can redistribute and/or modify it
 * under the terms specified in the file ``LICENSE'', which is part of
 * the lingerd distribution.  (For the impatient: it's an Apache-style
 * license, without the advertising clause.)
 *
 */

#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <signal.h>
#include <sys/param.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <sys/uio.h>

#include "httpd.h"
#include "http_log.h"
#define IN_APACHE
#include "li_config.h"

/* fd of the open lingerd connection, or -1 if there is none */
static int lingerd_fd	= -1;

/* time_t of the last time we tried to connect to lingerd */
static int last_try	= -1;


/*
 * Try to connect to the lingerd socket at most once every TRY_CONN_PERIOD
 * seconds; set lingerd_fd if successful.
 */
void lingerd_connect(void) {
  struct sockaddr_un sadr;
  int fd;
  struct timeval tv;

  if (lingerd_fd >= 0)
    return;

  gettimeofday(&tv, NULL);
  if (tv.tv_sec < last_try + TRY_CONN_PERIOD)
    return;

  last_try = tv.tv_sec;

  if ((fd = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
    return;

  sadr.sun_family = AF_UNIX;
  strncpy(sadr.sun_path, SOCKPATH, sizeof(sadr.sun_path));
  sadr.sun_path[sizeof(sadr.sun_path) - 1] = '\0';

  if (connect(fd, (struct sockaddr *)&sadr, sizeof(sadr)) < 0) {
    close(fd);
    ap_log_error(APLOG_MARK, APLOG_NOERRNO|APLOG_WARNING, NULL,
		 "Connection to lingerd socket (%s) failed", SOCKPATH);
    return;
  }

  lingerd_fd = fd;
}

/* 
 * Send an fd to the lingerd daemon.  Return 0 for success, -1 for unspecified
 * failure, and -2 for EPIPE on sendmsg()
 */
static int real_lingerd_sendfd (int fd) {
#ifndef OLD_FD_PASSING
  static lingerd_cmsghdr l_hdr;
  struct cmsghdr *hdr = &l_hdr.hdr;
#endif
  struct iovec iov;
  struct msghdr msg;
  char	aracter = 'Z';
  int	r;

  /* If we don't have a lingerd connection, try to open one */
  if (lingerd_fd < 0)
    lingerd_connect();
  
  /* If we *still* don't have a lingerd connection, fail */
  if (lingerd_fd < 0)
    return -1;

  /* 
   * Create the ancillary data to pass the fd.  Also send a single byte
   * of normal data along with it, or Linux won't wake up the daemon.
   */

  iov.iov_base    = &aracter;
  iov.iov_len     = 1;

#ifndef OLD_FD_PASSING
  memset((char *)&l_hdr, 0, sizeof(l_hdr));
#endif
  memset((char *)&msg,   0, sizeof(msg));

  msg.msg_iov     = &iov;
  msg.msg_iovlen  = 1;
  msg.msg_name    = NULL;
  msg.msg_namelen = 0;

#ifdef OLD_FD_PASSING
  msg.msg_accrights = (char *)&fd;
  msg.msg_accrightslen = sizeof(fd);
#else
  msg.msg_flags	  = 0;
  msg.msg_control = (char *)hdr;
  msg.msg_controllen = CONTROLLEN;
  hdr->cmsg_level = SOL_SOCKET;
  hdr->cmsg_len   = CONTROLLEN;
  hdr->cmsg_type  = SCM_RIGHTS;
  *(int *)CMSG_DATA(hdr) = fd;
#endif

  /* Try to send it */
  r = sendmsg(lingerd_fd, &msg, 0);

  /* Apache already ignores SIGPIPE for us.  Yay for Apache. */
  if (r < 0)
    return (errno == EPIPE ? -2 : -1);

  return 0;
}

/* 
 * Send an fd to the lingerd daemon.  Connect again if the existing
 * lingerd connection dies on us.
 */
int lingerd_sendfd (int fd) {
  int r;
  
  if ((r = real_lingerd_sendfd(fd)) != -2)
    return r;

  /* close the connection and try again. */
  if (lingerd_fd >= 0)
    close(lingerd_fd);
  lingerd_fd = -1;

  /* real_lingerd_fd will do the job of connecting again */
  return real_lingerd_sendfd(fd);
}