postkick.c

[詳解]

/*++
/* NAME
/*  postkick 1
/* SUMMARY
/*  kick a Postfix service
/* SYNOPSIS
/* .fi
/*  \fBpostkick\fR [\fB-c \fIconfig_dir\fR] [\fB-v\fR]
/*  \fIclass service request\fR
/* DESCRIPTION
/*  The \fBpostkick\fR(1) command sends \fIrequest\fR to the
/*  specified \fIservice\fR over a local transport channel.
/*  This command makes Postfix private IPC accessible
/*  for use in, for example, shell scripts.
/*
/*  Options:
/* .IP "\fB-c\fR \fIconfig_dir\fR"
/*  Read the \fBmain.cf\fR configuration file in the named directory
/*  instead of the default configuration directory.
/* .IP \fB-v\fR
/*  Enable verbose logging for debugging purposes. Multiple \fB-v\fR
/*  options make the software increasingly verbose.
/* .PP
/*  Arguments:
/* .IP \fIclass\fR
/*  Name of a class of local transport channel endpoints,
/*  either \fBpublic\fR (accessible by any local user) or
/*  \fBprivate\fR (administrative access only).
/* .IP \fIservice\fR
/*  The name of a local transport endpoint within the named class.
/* .IP \fIrequest\fR
/*  A string. The list of valid requests is service-specific.
/* DIAGNOSTICS
/*  Problems and transactions are logged to the standard error
/*  stream.
/* ENVIRONMENT
/* .ad
/* .fi
/* .IP \fBMAIL_CONFIG\fR
/*  Directory with Postfix configuration files.
/* .IP \fBMAIL_VERBOSE\fR
/*  Enable verbose logging for debugging purposes.
/* CONFIGURATION PARAMETERS
/* .ad
/* .fi
/*  The following \fBmain.cf\fR parameters are especially relevant to
/*  this program.
/*  The text below provides only a parameter summary. See
/*  \fBpostconf\fR(5) for more details including examples.
/* .IP "\fBconfig_directory (see 'postconf -d' output)\fR"
/*  The default location of the Postfix main.cf and master.cf
/*  configuration files.
/* .IP "\fBapplication_event_drain_time (100s)\fR"
/*  How long the \fBpostkick\fR(1) command waits for a request to enter the
/*  Postfix daemon process input buffer before giving up.
/* .IP "\fBimport_environment (see 'postconf -d' output)\fR"
/*  The list of environment parameters that a privileged Postfix
/*  process will import from a non-Postfix parent process, or name=value
/*  environment overrides.
/* .IP "\fBqueue_directory (see 'postconf -d' output)\fR"
/*  The location of the Postfix top-level queue directory.
/* FILES
/*  /var/spool/postfix/private, private class endpoints
/*  /var/spool/postfix/public, public class endpoints
/* SEE ALSO
/*  qmgr(8), queue manager trigger protocol
/*  pickup(8), local pickup daemon
/*  postconf(5), configuration parameters
/* LICENSE
/* .ad
/* .fi
/*  The Secure Mailer license must be distributed with this software.
/* AUTHOR(S)
/*  Wietse Venema
/*  IBM T.J. Watson Research
/*  P.O. Box 704
/*  Yorktown Heights, NY 10598, USA
/*
/*  Wietse Venema
/*  Google, Inc.
/*  111 8th Avenue
/*  New York, NY 10011, USA
/*--*/

/* System library. */

#include <sys_defs.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <syslog.h>
#include <string.h>
#include <stdlib.h>

/* Utility library. */

#include <msg.h>
#include <mymalloc.h>
#include <vstream.h>
#include <msg_vstream.h>
#include <safe.h>
#include <events.h>
#include <warn_stat.h>
#include <clean_env.h>

/* Global library. */

#include <mail_proto.h>
#include <mail_params.h>
#include <mail_version.h>
#include <mail_conf.h>
#include <mail_parm_split.h>

static NORETURN usage(char *myname)
{
    msg_fatal("usage: %s [-c config_dir] [-v] class service request", myname);
}

MAIL_VERSION_STAMP_DECLARE;

int     main(int argc, char **argv)
{
    char   *class;
    char   *service;
    char   *request;
    int     fd;
    struct stat st;
    char   *slash;
    int     c;
    ARGV   *import_env;

    /*
     * Fingerprint executables and core dumps.
     */
    MAIL_VERSION_STAMP_ALLOCATE;

    /*
     * To minimize confusion, make sure that the standard file descriptors
     * are open before opening anything else. XXX Work around for 44BSD where
     * fstat can return EBADF on an open file descriptor.
     */
    for (fd = 0; fd < 3; fd++)
    if (fstat(fd, &st) == -1
        && (close(fd), open("/dev/null", O_RDWR, 0)) != fd)
        msg_fatal("open /dev/null: %m");

    /*
     * Process environment options as early as we can.
     */
    if (safe_getenv(CONF_ENV_VERB))
    msg_verbose = 1;

    /*
     * Initialize. Set up logging, read the global configuration file and
     * extract configuration information.
     */
    if ((slash = strrchr(argv[0], '/')) != 0 && slash[1])
    argv[0] = slash + 1;
    msg_vstream_init(argv[0], VSTREAM_ERR);
    set_mail_conf_str(VAR_PROCNAME, var_procname = mystrdup(argv[0]));

    /*
     * Parse JCL.
     */
    while ((c = GETOPT(argc, argv, "c:v")) > 0) {
    switch (c) {
    default:
        usage(argv[0]);
    case 'c':
        if (setenv(CONF_ENV_PATH, optarg, 1) < 0)
        msg_fatal("out of memory");
        break;
    case 'v':
        msg_verbose++;
        break;
    }
    }
    if (argc != optind + 3)
    usage(argv[0]);
    class = argv[optind];
    service = argv[optind + 1];
    request = argv[optind + 2];

    /*
     * Finish initializations.
     */
    mail_conf_read();
    /* Enforce consistent operation of different Postfix parts. */
    import_env = mail_parm_split(VAR_IMPORT_ENVIRON, var_import_environ);
    update_env(import_env->argv);
    argv_free(import_env);
    if (chdir(var_queue_dir))
    msg_fatal("chdir %s: %m", var_queue_dir);

    /*
     * Kick the service.
     */
    if (mail_trigger(class, service, request, strlen(request)) < 0) {
    msg_warn("Cannot contact class %s service %s - perhaps the mail system is down",
         class, service);
    exit(1);
    }

    /*
     * Problem: With triggers over full duplex (i.e. non-FIFO) channels, we
     * must avoid closing the channel before the server has received the
     * request. Otherwise some hostile kernel may throw away the request.
     * 
     * Solution: The trigger routine registers a read event handler that runs
     * when the server closes the channel. The event_drain() routine waits
     * for the event handler to run, but gives up when it takes too long.
     */
    else {
    event_drain(var_event_drain);
    exit(0);
    }
}