smtp-sink.c

[詳解]

/*++
/* NAME
/*  smtp-sink 1
/* SUMMARY
/*  parallelized SMTP/LMTP test server
/* SYNOPSIS
/* .fi
/*  \fBsmtp-sink\fR [\fIoptions\fR] [\fBinet:\fR][\fIhost\fR]:\fIport\fR
/*  \fIbacklog\fR
/*
/*  \fBsmtp-sink\fR [\fIoptions\fR] \fBunix:\fR\fIpathname\fR \fIbacklog\fR
/* DESCRIPTION
/*  \fBsmtp-sink\fR listens on the named host (or address) and port.
/*  It takes SMTP messages from the network and throws them away.
/*  The purpose is to measure client performance, not protocol
/*  compliance.
/*
/*  \fBsmtp-sink\fR may also be configured to capture each mail
/*  delivery transaction to file. Since disk latencies are large
/*  compared to network delays, this mode of operation can
/*  reduce the maximal performance by several orders of magnitude.
/*
/*  Connections can be accepted on IPv4 or IPv6 endpoints, or on
/*  UNIX-domain sockets.
/*  IPv4 and IPv6 are the default.
/*  This program is the complement of the \fBsmtp-source\fR(1) program.
/*
/*  Note: this is an unsupported test program. No attempt is made
/*  to maintain compatibility between successive versions.
/*
/*  Arguments:
/* .IP \fB-4\fR
/*  Support IPv4 only. This option has no effect when
/*  Postfix is built without IPv6 support.
/* .IP \fB-6\fR
/*  Support IPv6 only. This option is not available when
/*  Postfix is built without IPv6 support.
/* .IP \fB-8\fR
/*  Do not announce 8BITMIME support.
/* .IP \fB-a\fR
/*  Do not announce SASL authentication support.
/* .IP "\fB-A \fIdelay\fR"
/*  Wait \fIdelay\fR seconds after responding to DATA, then
/*  abort prematurely with a 550 reply status.  Do not read
/*  further input from the client; this is an attempt to block
/*  the client before it sends ".".  Specify a zero delay value
/*  to abort immediately.
/* .IP "\fB-b \fIsoft-bounce-reply\fR"
/*  Use \fIsoft-bounce-reply\fR for soft reject responses.  The
/*  default reply is "450 4.3.0 Error: command failed".
/* .IP "\fB-B \fIhard-bounce-reply\fR"
/*  Use \fIhard-bounce-reply\fR for hard reject responses.  The
/*  default reply is "500 5.3.0 Error: command failed".
/* .IP \fB-c\fR
/*  Display running counters that are updated whenever an SMTP
/*  session ends, a QUIT command is executed, or when "." is
/*  received.
/* .IP \fB-C\fR
/*  Disable XCLIENT support.
/* .IP "\fB-d \fIdump-template\fR"
/*  Dump each mail transaction to a single-message file whose
/*  name is created by expanding the \fIdump-template\fR via
/*  strftime(3) and appending a pseudo-random hexadecimal number
/*  (example: "%Y%m%d%H/%M." expands into "2006081203/05.809a62e3").
/*  If the template contains "/" characters, missing directories
/*  are created automatically.  The message dump format is
/*  described below.
/* .sp
/*  Note: this option keeps one capture file open for every
/*  mail transaction in progress.
/* .IP "\fB-D \fIdump-template\fR"
/*  Append mail transactions to a multi-message dump file whose
/*  name is created by expanding the \fIdump-template\fR via
/*  strftime(3).
/*  If the template contains "/" characters, missing directories
/*  are created automatically.  The message dump format is
/*  described below.
/* .sp
/*  Note: this option keeps one capture file open for every
/*  mail transaction in progress.
/* .IP \fB-e\fR
/*  Do not announce ESMTP support.
/* .IP \fB-E\fR
/*  Do not announce ENHANCEDSTATUSCODES support.
/* .IP "\fB-f \fIcommand,command,...\fR"
/*  Reject the specified commands with a hard (5xx) error code.
/*  This option implies \fB-p\fR.
/* .sp
/*  Examples of commands are CONNECT, HELO, EHLO, LHLO, MAIL, RCPT, VRFY,
/*  DATA, ., RSET, NOOP, and QUIT. Separate command names by
/*  white space or commas, and use quotes to protect white space
/*  from the shell. Command names are case-insensitive.
/* .IP \fB-F\fR
/*  Disable XFORWARD support.
/* .IP "\fB-h\fI hostname\fR"
/*  Use \fIhostname\fR in the SMTP greeting, in the HELO response,
/*  and in the EHLO response. The default hostname is "smtp-sink".
/* .IP "\fB-H\fI delay\fR"
/*  Delay the first read operation after receiving DATA (time
/*  in seconds). Combine with a large test message and a small
/*  TCP window size (see the \fB-T\fR option) to test the Postfix
/*  client write_wait() implementation.
/* .IP \fB-L\fR
/*  Enable LMTP instead of SMTP.
/* .IP "\fB-m \fIcount\fR (default: 256)"
/*  An upper bound on the maximal number of simultaneous
/*  connections that \fBsmtp-sink\fR will handle. This prevents
/*  the process from running out of file descriptors. Excess
/*  connections will stay queued in the TCP/IP stack.
/* .IP "\fB-M \fIcount\fR"
/*  Terminate after receiving \fIcount\fR messages.
/* .IP "\fB-n \fIcount\fR"
/*  Terminate after \fIcount\fR sessions.
/* .IP \fB-N\fR
/*  Do not announce support for DSN.
/* .IP \fB-p\fR
/*  Do not announce support for ESMTP command pipelining.
/* .IP \fB-P\fR
/*  Change the server greeting so that it appears to come through
/*  a CISCO PIX system. Implies \fB-e\fR.
/* .IP "\fB-q \fIcommand,command,...\fR"
/*  Disconnect (without replying) after receiving one of the
/*  specified commands.
/* .sp
/*  Examples of commands are CONNECT, HELO, EHLO, LHLO, MAIL, RCPT, VRFY,
/*  DATA, ., RSET, NOOP, and QUIT. Separate command names by
/*  white space or commas, and use quotes to protect white space
/*  from the shell. Command names are case-insensitive.
/* .IP "\fB-Q \fIcommand,command,...\fR"
/*  Send a 421 reply and disconnect after receiving one
/*  of the specified commands.
/* .sp
/*  Examples of commands are CONNECT, HELO, EHLO, LHLO, MAIL, RCPT, VRFY,
/*  DATA, ., RSET, NOOP, and QUIT. Separate command names by
/*  white space or commas, and use quotes to protect white space
/*  from the shell. Command names are case-insensitive.
/* .IP "\fB-r \fIcommand,command,...\fR"
/*  Reject the specified commands with a soft (4xx) error code.
/*  This option implies \fB-p\fR.
/* .sp
/*  Examples of commands are CONNECT, HELO, EHLO, LHLO, MAIL, RCPT, VRFY,
/*  DATA, ., RSET, NOOP, and QUIT. Separate command names by
/*  white space or commas, and use quotes to protect white space
/*  from the shell. Command names are case-insensitive.
/* .IP "\fB-R \fIroot-directory\fR"
/*  Change the process root directory to the specified location.
/*  This option requires super-user privileges. See also the
/*  \fB-u\fR option.
/* .IP "\fB-s \fIcommand,command,...\fR"
/*  Log the named commands to syslogd.
/* .sp
/*  Examples of commands are CONNECT, HELO, EHLO, LHLO, MAIL, RCPT, VRFY,
/*  DATA, ., RSET, NOOP, and QUIT. Separate command names by
/*  white space or commas, and use quotes to protect white space
/*  from the shell. Command names are case-insensitive.
/* .IP "\fB-S start-string\fR"
/*  An optional string that is prepended to each message that is
/*  written to a dump file (see the dump file format description
/*  below). The following C escape sequences are supported: \ea
/*  (bell), \eb (backspace), \ef (formfeed), \en (newline), \er
/*  (carriage return), \et (horizontal tab), \ev (vertical tab),
/*  \e\fIddd\fR (up to three octal digits) and \e\e (the backslash
/*  character).
/* .IP "\fB-t \fItimeout\fR (default: 100)"
/*  Limit the time for receiving a command or sending a response.
/*  The time limit is specified in seconds.
/* .IP "\fB-T \fIwindowsize\fR"
/*  Override the default TCP window size. To work around
/*  broken TCP window scaling implementations, specify a
/*  value > 0 and < 65536.
/* .IP "\fB-u \fIusername\fR"
/*  Switch to the specified user privileges after opening the
/*  network socket and optionally changing the process root
/*  directory. This option is required when the process runs
/*  with super-user privileges. See also the \fB-R\fR option.
/* .IP \fB-v\fR
/*  Show the SMTP conversations.
/* .IP "\fB-w \fIdelay\fR"
/*  Wait \fIdelay\fR seconds before responding to a DATA command.
/* .IP "\fB-W \fIcommand:delay[:odds]\fR"
/*  Wait \fIdelay\fR seconds before responding to \fIcommand\fR.
/*  If \fIodds\fR is also specified (a number between 1-99
/*  inclusive), wait for a random multiple of \fIdelay\fR. The
/*  random multiplier is equal to the number of times the program
/*  needs to roll a dice with a range of 0..99 inclusive, before
/*  the dice produces a result greater than or equal to \fIodds\fR.
/* .IP [\fBinet:\fR][\fIhost\fR]:\fIport\fR
/*  Listen on network interface \fIhost\fR (default: any interface)
/*  TCP port \fIport\fR. Both \fIhost\fR and \fIport\fR may be
/*  specified in numeric or symbolic form.
/* .IP \fBunix:\fR\fIpathname\fR
/*  Listen on the UNIX-domain socket at \fIpathname\fR.
/* .IP \fIbacklog\fR
/*  The maximum length the queue of pending connections,
/*  as defined by the \fBlisten\fR(2) system call.
/* DUMP FILE FORMAT
/* .ad
/* .fi
/*  Each dumped message contains a sequence of text lines,
/*  terminated with the newline character. The sequence of
/*  information is as follows:
/* .IP \(bu
/*  The optional string specified with the \fB-S\fR option.
/* .IP \(bu
/*  The \fBsmtp-sink\fR generated headers as documented below.
/* .IP \(bu
/*  The message header and body as received from the SMTP client.
/* .IP \(bu
/*  An empty line.
/* .PP
/*  The format of the \fBsmtp-sink\fR generated headers is as
/*  follows:
/* .IP "\fBX-Client-Addr: \fItext\fR"
/*  The client IP address without enclosing []. An IPv6 address
/*  is prefixed with "ipv6:". This record is always present.
/* .IP "\fBX-Client-Proto: \fItext\fR"
/*  The client protocol: SMTP, ESMTP or LMTP. This record is
/*  always present.
/* .IP "\fBX-Helo-Args: \fItext\fR"
/*  The arguments of the last HELO or EHLO command before this
/*  mail delivery transaction. This record is present only if
/*  the client sent a recognizable HELO or EHLO command before
/*  the DATA command.
/* .IP "\fBX-Mail-Args: \fItext\fR"
/*  The arguments of the MAIL command that started this mail
/*  delivery transaction. This record is present exactly once.
/* .IP "\fBX-Rcpt-Args: \fItext\fR"
/*  The arguments of an RCPT command within this mail delivery
/*  transaction. There is one record for each RCPT command, and
/*  they are in the order as sent by the client.
/* .IP "\fBReceived: \fItext\fR"
/*  A message header for compatibility with mail processing
/*  software. This three-line header marks the end of the headers
/*  provided by \fBsmtp-sink\fR, and is formatted as follows:
/* .RS
/* .IP "\fBfrom \fIhelo\fR ([\fIaddr\fR])"
/*  The HELO or EHLO command argument and client IP address.
/*  If the client did not send HELO or EHLO, the client IP
/*  address is used instead.
/* .IP "\fBby \fIhost\fB (smtp-sink) with \fIproto\fB id \fIrandom\fB;\fR"
/*  The hostname specified with the \fB-h\fR option, the client
/*  protocol (see \fBX-Client-Proto\fR above), and the pseudo-random
/*  portion of the per-message capture file name.
/* .IP \fItime-stamp\fR
/*  A time stamp as defined in RFC 2822.
/* .RE
/* SEE ALSO
/*  smtp-source(1), SMTP/LMTP message generator
/* 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/socket.h>
#include <sys/wait.h>
#include <sys/stat.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include <fcntl.h>
#include <syslog.h>
#include <signal.h>
#include <time.h>
#include <ctype.h>

#ifdef STRCASECMP_IN_STRINGS_H
#include <strings.h>
#endif

/* Utility library. */

#include <msg.h>
#include <vstring.h>
#include <vstream.h>
#include <vstring_vstream.h>
#include <get_hostname.h>
#include <listen.h>
#include <events.h>
#include <mymalloc.h>
#include <iostuff.h>
#include <msg_vstream.h>
#include <stringops.h>
#include <sane_accept.h>
#include <inet_proto.h>
#include <myaddrinfo.h>
#include <make_dirs.h>
#include <myrand.h>
#include <chroot_uid.h>

/* Global library. */

#include <smtp_stream.h>
#include <mail_date.h>
#include <mail_version.h>

/* Application-specific. */

typedef struct SINK_STATE {
    VSTREAM *stream;
    VSTRING *buffer;
    int     data_state;
    int     (*read_fn) (struct SINK_STATE *);
    int     in_mail;
    int     rcpts;
    char   *push_back_ptr;
    /* Capture file information for fake Received: header */
    MAI_HOSTADDR_STR client_addr;   /* IP address */
    char   *addr_prefix;        /* ipv6: or empty */
    char   *helo_args;          /* text after HELO or EHLO */
    const char *client_proto;       /* SMTP, ESMTP, LMTP */
    time_t  start_time;         /* MAIL command time */
    int     id;             /* pseudo-random */
    VSTREAM *dump_file;         /* dump file or null */
    void    (*delayed_response) (struct SINK_STATE *state, const char *);
    char   *delayed_args;
} SINK_STATE;

#define ST_ANY          0
#define ST_CR           1
#define ST_CR_LF        2
#define ST_CR_LF_DOT        3
#define ST_CR_LF_DOT_CR     4
#define ST_CR_LF_DOT_CR_LF  5

#define PUSH_BACK_PEEK(state)       (*(state)->push_back_ptr != 0)
#define PUSH_BACK_GET(state)        (*(state)->push_back_ptr++)
#define PUSH_BACK_SET(state, text)  ((state)->push_back_ptr = (text))

#ifndef DEF_MAX_CLIENT_COUNT
#define DEF_MAX_CLIENT_COUNT    256
#endif

#define SOFT_ERROR_RESP     "450 4.3.0 Error: command failed"
#define HARD_ERROR_RESP     "500 5.3.0 Error: command failed"

 /*
  * We can't rely on vstream auto-flushing, so we have to prepare for the
  * next read request.
  */
#define SMTP_FLUSH(fp) do { \
    if (vstream_peek(fp) <= 0 && readable(vstream_fileno(fp)) <= 0) \
        smtp_flush(fp); \
    } while (0)

static int var_tmout = 100;
static int var_max_line_length = 2048;
static char *var_myhostname;
static char *soft_error_resp = SOFT_ERROR_RESP;
static char *hard_error_resp = HARD_ERROR_RESP;
static int command_read(SINK_STATE *);
static int data_read(SINK_STATE *);
static void disconnect(SINK_STATE *);
static void read_timeout(int, void *);
static void read_event(int, void *);
static int show_count;
static int sess_count;
static int quit_count;
static int mesg_count;
static int max_quit_count;
static int max_msg_quit_count;
static int disable_pipelining;
static int disable_8bitmime;
static int disable_esmtp;
static int enable_lmtp;
static int pretend_pix;
static int disable_saslauth;
static int disable_xclient;
static int disable_xforward;
static int disable_enh_status;
static int disable_dsn;
static int max_client_count = DEF_MAX_CLIENT_COUNT;
static int client_count;
static int sock;
static int abort_delay = -1;
static int data_read_delay = 0;

static char *single_template;       /* individual template */
static char *shared_template;       /* shared template */
static VSTRING *start_string;       /* dump content prefix */

static INET_PROTO_INFO *proto_info;

#define STR(x)  vstring_str(x)

/* do_stats - show counters */

static void do_stats(void)
{
    vstream_printf("sess=%d quit=%d mesg=%d\r",
           sess_count, quit_count, mesg_count);
    vstream_fflush(VSTREAM_OUT);
}

/* hard_err_resp - generic hard error response */

static void hard_err_resp(SINK_STATE *state)
{
    smtp_printf(state->stream, "%s", hard_error_resp);
    SMTP_FLUSH(state->stream);
}

/* soft_err_resp - generic soft error response */

static void soft_err_resp(SINK_STATE *state)
{
    smtp_printf(state->stream, "%s", soft_error_resp);
    SMTP_FLUSH(state->stream);
}

/* exp_path_template - expand template pathname, static result */

static VSTRING *exp_path_template(const char *template, time_t start_time)
{
    static VSTRING *path_buf = 0;
    struct tm *lt;

    if (path_buf == 0)
    path_buf = vstring_alloc(100);
    else
    VSTRING_RESET(path_buf);
    lt = localtime(&start_time);
    while (strftime(STR(path_buf), vstring_avail(path_buf), template, lt) == 0)
    VSTRING_SPACE(path_buf, vstring_avail(path_buf) + 100);
    VSTRING_SKIP(path_buf);
    return (path_buf);
}

/* make_parent_dir - create parent directory or bust */

static void make_parent_dir(const char *path, mode_t mode)
{
    const char *parent;

    parent = sane_dirname((VSTRING *) 0, path);
    if (make_dirs(parent, mode) < 0)
    msg_fatal("mkdir %s: %m", parent);
}

/* mail_file_open - open mail capture file */

static void mail_file_open(SINK_STATE *state)
{
    const char *myname = "mail_file_open";
    VSTRING *path_buf;
    ssize_t len;
    int     tries = 0;

    /*
     * Save the start time for later.
     */
    time(&(state->start_time));

    /*
     * Expand the per-message dumpfile pathname template.
     */
    path_buf = exp_path_template(single_template, state->start_time);

    /*
     * Append a random hexadecimal string to the pathname and create a new
     * file. Retry with a different path if the file already exists. Create
     * intermediate directories on the fly when the template specifies
     * multiple pathname segments.
     */
#define ID_FORMAT   "%08x"

    for (len = VSTRING_LEN(path_buf); /* void */ ; vstring_truncate(path_buf, len)) {
    if (++tries > 100)
        msg_fatal("%s: something is looping", myname);
    state->id = myrand();
    vstring_sprintf_append(path_buf, ID_FORMAT, state->id);
    if ((state->dump_file = vstream_fopen(STR(path_buf),
                          O_RDWR | O_CREAT | O_EXCL,
                          0644)) != 0) {
        break;
    } else if (errno == EEXIST) {
        continue;
    } else if (errno == ENOENT) {
        make_parent_dir(STR(path_buf), 0755);
        continue;
    } else {
        msg_fatal("open %s: %m", STR(path_buf));
    }
    }

    /*
     * Don't leave temporary files behind.
     */
    if (shared_template != 0 && unlink(STR(path_buf)) < 0)
    msg_fatal("unlink %s: %m", STR(path_buf));

    /*
     * Do initial header records.
     */
    if (start_string)
    vstream_fprintf(state->dump_file, "%s", STR(start_string));
    vstream_fprintf(state->dump_file, "X-Client-Addr: %s%s\n",
            state->addr_prefix, state->client_addr.buf);
    vstream_fprintf(state->dump_file, "X-Client-Proto: %s\n", state->client_proto);
    if (state->helo_args)
    vstream_fprintf(state->dump_file, "X-Helo-Args: %s\n", state->helo_args);
    /* Note: there may be more than one recipient. */
}

/* mail_file_finish_header - do final smtp-sink generated header records */

static void mail_file_finish_header(SINK_STATE *state)
{
    if (state->helo_args)
    vstream_fprintf(state->dump_file, "Received: from %s ([%s%s])\n",
            state->helo_args, state->addr_prefix,
            state->client_addr.buf);
    else
    vstream_fprintf(state->dump_file, "Received: from [%s%s] ([%s%s])\n",
            state->addr_prefix, state->client_addr.buf,
            state->addr_prefix, state->client_addr.buf);
    vstream_fprintf(state->dump_file, "\tby %s (smtp-sink)"
            " with %s id " ID_FORMAT ";\n",
            var_myhostname, state->client_proto, state->id);
    vstream_fprintf(state->dump_file, "\t%s\n", mail_date(state->start_time));
}

/* mail_file_cleanup - common cleanup for capture file */

static void mail_file_cleanup(SINK_STATE *state)
{
    (void) vstream_fclose(state->dump_file);
    state->dump_file = 0;
}

/* mail_file_finish - handle message completion for capture file */

static void mail_file_finish(SINK_STATE *state)
{

    /*
     * Optionally append the captured message to a shared dumpfile.
     */
    if (shared_template) {
    const char *out_path;
    VSTREAM *out_fp;
    ssize_t count;

    /*
     * Expand the shared dumpfile pathname template.
     */
    out_path = STR(exp_path_template(shared_template, state->start_time));

    /*
     * Open the shared dump file.
     */
#define OUT_OPEN_FLAGS  (O_WRONLY | O_CREAT | O_APPEND)
#define OUT_OPEN_MODE   0644

    if ((out_fp = vstream_fopen(out_path, OUT_OPEN_FLAGS, OUT_OPEN_MODE))
        == 0 && errno == ENOENT) {
        make_parent_dir(out_path, 0755);
        out_fp = vstream_fopen(out_path, OUT_OPEN_FLAGS, OUT_OPEN_MODE);
    }
    if (out_fp == 0)
        msg_fatal("open %s: %m", out_path);

    /*
     * Append message content from single-message dump file.
     */
    if (vstream_fseek(state->dump_file, 0L, SEEK_SET) < 0)
        msg_fatal("seek file %s: %m", VSTREAM_PATH(state->dump_file));
    VSTRING_RESET(state->buffer);
    for (;;) {
        count = vstream_fread(state->dump_file, STR(state->buffer),
                  vstring_avail(state->buffer));
        if (count <= 0)
        break;
        if (vstream_fwrite(out_fp, STR(state->buffer), count) != count)
        msg_fatal("append file %s: %m", out_path);
    }
    if (vstream_ferror(state->dump_file))
        msg_fatal("read file %s: %m", VSTREAM_PATH(state->dump_file));
    if (vstream_fclose(out_fp))
        msg_fatal("append file %s: %m", out_path);
    }
    mail_file_cleanup(state);
}

/* mail_file_reset - abort mail to capture file */

static void mail_file_reset(SINK_STATE *state)
{
    if (shared_template == 0
    && unlink(VSTREAM_PATH(state->dump_file)) < 0
    && errno != ENOENT)
    msg_fatal("unlink %s: %m", VSTREAM_PATH(state->dump_file));
    mail_file_cleanup(state);
}

/* mail_cmd_reset - reset mail transaction information */

static void mail_cmd_reset(SINK_STATE *state)
{
    state->in_mail = 0;
    /* Not: state->rcpts = 0. This breaks the DOT reply with LMTP. */
    if (state->dump_file)
    mail_file_reset(state);
}

/* ehlo_response - respond to EHLO command */

static void ehlo_response(SINK_STATE *state, const char *args)
{
#define SKIP(cp, cond) do { \
    for (/* void */; *cp && (cond); cp++) \
        /* void */; \
    } while (0)

    /* EHLO aborts a mail transaction in progress. */
    mail_cmd_reset(state);
    if (enable_lmtp == 0)
    state->client_proto = "ESMTP";
    smtp_printf(state->stream, "250-%s", var_myhostname);
    if (!disable_pipelining)
    smtp_printf(state->stream, "250-PIPELINING");
    if (!disable_8bitmime)
    smtp_printf(state->stream, "250-8BITMIME");
    if (!disable_saslauth)
    smtp_printf(state->stream, "250-AUTH PLAIN LOGIN");
    if (!disable_xclient)
    smtp_printf(state->stream, "250-XCLIENT NAME HELO");
    if (!disable_xforward)
    smtp_printf(state->stream, "250-XFORWARD NAME ADDR PROTO HELO");
    if (!disable_enh_status)
    smtp_printf(state->stream, "250-ENHANCEDSTATUSCODES");
    if (!disable_dsn)
    smtp_printf(state->stream, "250-DSN");
    /* RFC 821/2821/5321: Format is replycode<SPACE>optional-text<CRLF> */
    smtp_printf(state->stream, "250 ");
    SMTP_FLUSH(state->stream);
    if (single_template) {
    if (state->helo_args)
        myfree(state->helo_args);
    SKIP(args, ISSPACE(*args));
    state->helo_args = mystrdup(args);
    }
}

/* helo_response - respond to HELO command */

static void helo_response(SINK_STATE *state, const char *args)
{
    /* HELO aborts a mail transaction in progress. */
    mail_cmd_reset(state);
    state->client_proto = "SMTP";
    smtp_printf(state->stream, "250 %s", var_myhostname);
    SMTP_FLUSH(state->stream);
    if (single_template) {
    if (state->helo_args)
        myfree(state->helo_args);
    SKIP(args, ISSPACE(*args));
    state->helo_args = mystrdup(args);
    }
}

/* ok_response - send 250 OK */

static void ok_response(SINK_STATE *state, const char *unused_args)
{
    smtp_printf(state->stream, "250 2.0.0 Ok");
    SMTP_FLUSH(state->stream);
}

/* rset_response - reset, send 250 OK */

static void rset_response(SINK_STATE *state, const char *unused_args)
{
    mail_cmd_reset(state);
    smtp_printf(state->stream, "250 2.1.0 Ok");
    SMTP_FLUSH(state->stream);
}

/* mail_response - reset recipient count, send 250 OK */

static void mail_response(SINK_STATE *state, const char *args)
{
    if (state->in_mail) {
    smtp_printf(state->stream, "503 5.5.1 Error: nested MAIL command");
    SMTP_FLUSH(state->stream);
    return;
    }
    state->in_mail++;
    state->rcpts = 0;
    smtp_printf(state->stream, "250 2.1.0 Ok");
    SMTP_FLUSH(state->stream);
    if (single_template) {
    mail_file_open(state);
    SKIP(args, *args != ':');
    SKIP(args, *args == ':');
    SKIP(args, ISSPACE(*args));
    vstream_fprintf(state->dump_file, "X-Mail-Args: %s\n", args);
    }
}

/* rcpt_response - bump recipient count, send 250 OK */

static void rcpt_response(SINK_STATE *state, const char *args)
{
    if (state->in_mail == 0) {
    smtp_printf(state->stream, "503 5.5.1 Error: need MAIL command");
    SMTP_FLUSH(state->stream);
    return;
    }
    state->rcpts++;
    smtp_printf(state->stream, "250 2.1.5 Ok");
    SMTP_FLUSH(state->stream);
    /* Note: there may be more than one recipient per mail transaction. */
    if (state->dump_file) {
    SKIP(args, *args != ':');
    SKIP(args, *args == ':');
    SKIP(args, ISSPACE(*args));
    vstream_fprintf(state->dump_file, "X-Rcpt-Args: %s\n", args);
    }
}

/* abort_event - delayed abort after DATA command */

static void abort_event(int unused_event, void *context)
{
    SINK_STATE *state = (SINK_STATE *) context;

    smtp_printf(state->stream, "550 This violates SMTP");
    SMTP_FLUSH(state->stream);
    disconnect(state);
}

/* delay_read_event - resume input event handling */

static void delay_read_event(int event, void *context)
{
    SINK_STATE *state = (SINK_STATE *) context;

    if (event != EVENT_TIME)
    msg_panic("delay_read_event: non-timer event %d", event);

    event_enable_read(vstream_fileno(state->stream), read_event, (void *) state);
    event_request_timer(read_timeout, (void *) state, var_tmout);
}

/* delay_read - temporarily suspend input event handling */

static void delay_read(SINK_STATE *state, int delay)
{
    event_disable_readwrite(vstream_fileno(state->stream));
    event_cancel_timer(read_timeout, (void *) state);
    event_request_timer(delay_read_event, (void *) state, delay);
}

/* data_response - respond to DATA command */

static void data_response(SINK_STATE *state, const char *unused_args)
{
    if (state->in_mail == 0 || state->rcpts == 0) {
    smtp_printf(state->stream, "503 5.5.1 Error: need RCPT command");
    SMTP_FLUSH(state->stream);
    return;
    }
    /* Not: ST_ANY. */
    state->data_state = ST_CR_LF;
    smtp_printf(state->stream, "354 End data with <CR><LF>.<CR><LF>");
    SMTP_FLUSH(state->stream);
    if (abort_delay < 0) {
    state->read_fn = data_read;
    /* Todo: move into code that invokes the command response function. */
    if (data_read_delay > 0)
        delay_read(state, data_read_delay);
    } else {
    /* Stop reading, send premature 550, and disconnect. */
    event_disable_readwrite(vstream_fileno(state->stream));
    event_cancel_timer(read_event, (void *) state);
    event_request_timer(abort_event, (void *) state, abort_delay);
    }
    if (state->dump_file)
    mail_file_finish_header(state);
}

/* dot_resp_hard - hard error response to . command */

static void dot_resp_hard(SINK_STATE *state)
{
    if (enable_lmtp) {
    while (state->rcpts-- > 0)  /* XXX this could block */
        smtp_printf(state->stream, "%s", hard_error_resp);
    } else {
    smtp_printf(state->stream, "%s", hard_error_resp);
    }
    SMTP_FLUSH(state->stream);
}

/* dot_resp_soft - soft error response to . command */

static void dot_resp_soft(SINK_STATE *state)
{
    if (enable_lmtp) {
    while (state->rcpts-- > 0)  /* XXX this could block */
        smtp_printf(state->stream, "%s", soft_error_resp);
    } else {
    smtp_printf(state->stream, "%s", soft_error_resp);
    }
    SMTP_FLUSH(state->stream);
}

/* dot_response - response to . command */

static void dot_response(SINK_STATE *state, const char *unused_args)
{
    if (enable_lmtp) {
    while (state->rcpts-- > 0)  /* XXX this could block */
        smtp_printf(state->stream, "250 2.2.0 Ok");
    } else {
    smtp_printf(state->stream, "250 2.0.0 Ok");
    }
    SMTP_FLUSH(state->stream);
}

/* quit_response - respond to QUIT command */

static void quit_response(SINK_STATE *state, const char *unused_args)
{
    smtp_printf(state->stream, "221 Bye");
    smtp_flush(state->stream);          /* not: SMTP_FLUSH */
    if (show_count)
    quit_count++;
}

/* conn_response - respond to connect command */

static void conn_response(SINK_STATE *state, const char *unused_args)
{
    if (pretend_pix)
    smtp_printf(state->stream, "220 ********");
    else if (disable_esmtp)
    smtp_printf(state->stream, "220 %s", var_myhostname);
    else
    smtp_printf(state->stream, "220 %s ESMTP", var_myhostname);
    SMTP_FLUSH(state->stream);
}

/* delay_event - delayed command response */

static void delay_event(int unused_event, void *context)
{
    SINK_STATE *state = (SINK_STATE *) context;

    switch (vstream_setjmp(state->stream)) {

    default:
    msg_panic("unknown read/write error");
    /* NOTREACHED */

    case SMTP_ERR_TIME:
    msg_warn("write timeout");
    disconnect(state);
    return;

    case SMTP_ERR_EOF:
    msg_warn("lost connection");
    disconnect(state);
    return;

    case 0:
    state->delayed_response(state, state->delayed_args);
    myfree(state->delayed_args);
    state->delayed_args = 0;
    break;
    }

    if (state->delayed_response == quit_response) {
    disconnect(state);
    return;
    }
    state->delayed_response = 0;

    /* Resume input event handling after the delayed response. */
    event_enable_read(vstream_fileno(state->stream), read_event, (void *) state);
    event_request_timer(read_timeout, (void *) state, var_tmout);
}

/* data_read - read data from socket */

static int data_read(SINK_STATE *state)
{
    int     ch;
    struct data_trans {
    int     state;
    int     want;
    int     next_state;
    };
    static struct data_trans data_trans[] = {
    ST_ANY, '\r', ST_CR,
    ST_CR, '\n', ST_CR_LF,
    ST_CR_LF, '.', ST_CR_LF_DOT,
    ST_CR_LF_DOT, '\r', ST_CR_LF_DOT_CR,
    ST_CR_LF_DOT_CR, '\n', ST_CR_LF_DOT_CR_LF,
    };
    struct data_trans *dp;

    /*
     * A read may result in EOF, but is never supposed to time out - a time
     * out means that we were trying to read when no data was available.
     */
    for (;;) {
    if ((ch = VSTREAM_GETC(state->stream)) == VSTREAM_EOF)
        return (-1);
    for (dp = data_trans; dp->state != state->data_state; dp++)
         /* void */ ;

    /*
     * Try to match the current character desired by the state machine.
     * If that fails, try to restart the machine with a match for its
     * first state.  This covers the case of a CR/LF/CR/LF sequence
     * (empty line) right before the end of the message data.
     */
    if (ch == dp->want)
        state->data_state = dp->next_state;
    else if (ch == data_trans[0].want)
        state->data_state = data_trans[0].next_state;
    else
        state->data_state = ST_ANY;
    if (state->dump_file) {
        if (ch != '\r' && state->data_state != ST_CR_LF_DOT)
        VSTREAM_PUTC(ch, state->dump_file);
        if (vstream_ferror(state->dump_file))
        msg_fatal("append file %s: %m", VSTREAM_PATH(state->dump_file));
    }
    if (state->data_state == ST_CR_LF_DOT_CR_LF) {
        PUSH_BACK_SET(state, ".\r\n");
        state->read_fn = command_read;
        state->data_state = ST_ANY;
        if (state->dump_file)
        mail_file_finish(state);
        mail_cmd_reset(state);
        if (show_count || max_msg_quit_count > 0) {
        mesg_count++;
        if (show_count)
            do_stats();
        if (max_msg_quit_count > 0 && mesg_count >= max_msg_quit_count)
            exit(0);
        }
        break;
    }

    /*
     * We must avoid blocking I/O, so get out of here as soon as both the
     * VSTREAM and kernel read buffers dry up.
     */
    if (vstream_peek(state->stream) <= 0
        && readable(vstream_fileno(state->stream)) <= 0)
        return (0);
    }
    return (0);
}

 /*
  * The table of all SMTP commands that we can handle.
  */
typedef struct SINK_COMMAND {
    const char *name;
    void    (*response) (SINK_STATE *, const char *);
    void    (*hard_response) (SINK_STATE *);
    void    (*soft_response) (SINK_STATE *);
    int     flags;
    int     delay;
    int     delay_odds;
} SINK_COMMAND;

#define FLAG_ENABLE (1<<0)      /* command is enabled */
#define FLAG_SYSLOG (1<<1)      /* log the command */
#define FLAG_HARD_ERR   (1<<2)      /* report hard error */
#define FLAG_SOFT_ERR   (1<<3)      /* report soft error */
#define FLAG_DISCONNECT (1<<4)      /* disconnect */
#define FLAG_CLOSE  (1<<5)      /* say goodbye and disconnect */

static SINK_COMMAND command_table[] = {
    "connect", conn_response, hard_err_resp, soft_err_resp, 0, 0, 0,
    "helo", helo_response, hard_err_resp, soft_err_resp, 0, 0, 0,
    "ehlo", ehlo_response, hard_err_resp, soft_err_resp, 0, 0, 0,
    "lhlo", ehlo_response, hard_err_resp, soft_err_resp, 0, 0, 0,
    "xclient", ok_response, hard_err_resp, soft_err_resp, FLAG_ENABLE, 0, 0,
    "xforward", ok_response, hard_err_resp, soft_err_resp, FLAG_ENABLE, 0, 0,
    "auth", ok_response, hard_err_resp, soft_err_resp, FLAG_ENABLE, 0, 0,
    "mail", mail_response, hard_err_resp, soft_err_resp, FLAG_ENABLE, 0, 0,
    "rcpt", rcpt_response, hard_err_resp, soft_err_resp, FLAG_ENABLE, 0, 0,
    "data", data_response, hard_err_resp, soft_err_resp, FLAG_ENABLE, 0, 0,
    ".", dot_response, dot_resp_hard, dot_resp_soft, FLAG_ENABLE, 0, 0,
    "rset", rset_response, hard_err_resp, soft_err_resp, FLAG_ENABLE, 0, 0,
    "noop", ok_response, hard_err_resp, soft_err_resp, FLAG_ENABLE, 0, 0,
    "vrfy", ok_response, hard_err_resp, soft_err_resp, FLAG_ENABLE, 0, 0,
    "quit", quit_response, hard_err_resp, soft_err_resp, FLAG_ENABLE, 0, 0,
    0,
};

/* reset_cmd_flags - reset per-command command flags */

static void reset_cmd_flags(const char *cmd, int flags)
{
    SINK_COMMAND *cmdp;

    for (cmdp = command_table; cmdp->name != 0; cmdp++)
    if (strcasecmp(cmd, cmdp->name) == 0)
        break;
    if (cmdp->name == 0)
    msg_fatal("unknown command: %s", cmd);
    cmdp->flags &= ~flags;
}

/* set_cmd_flags - set per-command command flags */

static void set_cmd_flags(const char *cmd, int flags)
{
    SINK_COMMAND *cmdp;

    for (cmdp = command_table; cmdp->name != 0; cmdp++)
    if (strcasecmp(cmd, cmdp->name) == 0)
        break;
    if (cmdp->name == 0)
    msg_fatal("unknown command: %s", cmd);
    cmdp->flags |= flags;
}

/* set_cmds_flags - set per-command flags for multiple commands */

static void set_cmds_flags(const char *cmds, int flags)
{
    char   *saved_cmds;
    char   *cp;
    char   *cmd;

    saved_cmds = cp = mystrdup(cmds);
    while ((cmd = mystrtok(&cp, CHARS_COMMA_SP)) != 0)
    set_cmd_flags(cmd, flags);
    myfree(saved_cmds);
}

/* set_cmd_delay - set per-command delay */

static void set_cmd_delay(const char *cmd, int delay, int odds)
{
    SINK_COMMAND *cmdp;

    for (cmdp = command_table; cmdp->name != 0; cmdp++)
    if (strcasecmp(cmd, cmdp->name) == 0)
        break;
    if (cmdp->name == 0)
    msg_fatal("unknown command: %s", cmd);

    if (delay <= 0)
    msg_fatal("non-positive '%s' delay", cmd);
    if (odds < 0 || odds > 99)
    msg_fatal("delay odds for '%s' out of range", cmd);

    cmdp->delay = delay;
    cmdp->delay_odds = odds;
}

/* set_cmd_delay_arg - set per-command delay from option argument */

static void set_cmd_delay_arg(char *arg)
{
    char   *cp;
    char   *saved_arg;
    char   *cmd;
    char   *delay;
    char   *odds;

    saved_arg = cp = mystrdup(arg);
    cmd = mystrtok(&cp, ":");
    delay = mystrtok(&cp, ":");
    if (cmd == 0 || delay == 0)
    msg_fatal("invalid command delay argument: %s", arg);
    odds = mystrtok(&cp, "");
    set_cmd_delay(cmd, atoi(delay), odds ? atoi(odds) : 0);
    myfree(saved_arg);
}

/* command_resp - respond to command */

static int command_resp(SINK_STATE *state, SINK_COMMAND *cmdp,
                    const char *command, const char *args)
{
    /* We use raw syslog. Sanitize data content and length. */
    if (cmdp->flags & FLAG_SYSLOG)
    syslog(LOG_INFO, "%s %.100s", command, args);
    if (cmdp->flags & FLAG_DISCONNECT)
    return (-1);
    if (cmdp->flags & FLAG_CLOSE) {
    smtp_printf(state->stream, "421 4.0.0 Server closing connection");
    return (-1);
    }
    if (cmdp->flags & FLAG_HARD_ERR) {
    cmdp->hard_response(state);
    return (0);
    }
    if (cmdp->flags & FLAG_SOFT_ERR) {
    cmdp->soft_response(state);
    return (0);
    }
    if (cmdp->delay > 0) {
    int     delay = cmdp->delay;

    if (cmdp->delay_odds > 0)
        for (delay = 0;
         ((int) (100.0 * rand() / (RAND_MAX + 1.0))) < cmdp->delay_odds;
         delay += cmdp->delay)
         /* NOP */ ;
    /* Suspend input event handling while delaying the command response. */
    event_disable_readwrite(vstream_fileno(state->stream));
    event_cancel_timer(read_timeout, (void *) state);
    event_request_timer(delay_event, (void *) state, delay);
    state->delayed_response = cmdp->response;
    state->delayed_args = mystrdup(args);
    } else {
    cmdp->response(state, args);
    if (cmdp->response == quit_response)
        return (-1);
    }
    return (0);
}

/* command_read - talk the SMTP protocol, server side */

static int command_read(SINK_STATE *state)
{
    char   *command;
    SINK_COMMAND *cmdp;
    int     ch;
    struct cmd_trans {
    int     state;
    int     want;
    int     next_state;
    };
    static struct cmd_trans cmd_trans[] = {
    ST_ANY, '\r', ST_CR,
    ST_CR, '\n', ST_CR_LF,
    0, 0, 0,
    };
    struct cmd_trans *cp;
    char   *ptr;

    /*
     * A read may result in EOF, but is never supposed to time out - a time
     * out means that we were trying to read when no data was available.
     */
#define NEXT_CHAR(state) \
    (PUSH_BACK_PEEK(state) ? PUSH_BACK_GET(state) : VSTREAM_GETC(state->stream))

    if (state->data_state == ST_CR_LF)
    state->data_state = ST_ANY;     /* XXX */
    for (;;) {
    if ((ch = NEXT_CHAR(state)) == VSTREAM_EOF)
        return (-1);

    /*
     * Sanity check. We don't want to store infinitely long commands.
     */
    if (VSTRING_LEN(state->buffer) >= var_max_line_length) {
        msg_warn("command line too long");
        return (-1);
    }
    VSTRING_ADDCH(state->buffer, ch);

    /*
     * Try to match the current character desired by the state machine.
     * If that fails, try to restart the machine with a match for its
     * first state.
     */
    for (cp = cmd_trans; cp->state != state->data_state; cp++)
        if (cp->want == 0)
        msg_panic("command_read: unknown state: %d", state->data_state);
    if (ch == cp->want)
        state->data_state = cp->next_state;
    else if (ch == cmd_trans[0].want)
        state->data_state = cmd_trans[0].next_state;
    else
        state->data_state = ST_ANY;
    if (state->data_state == ST_CR_LF)
        break;

    /*
     * We must avoid blocking I/O, so get out of here as soon as both the
     * VSTREAM and kernel read buffers dry up.
     * 
     * XXX Solaris non-blocking read() may fail on a socket when ioctl
     * FIONREAD reports there is unread data. Diagnosis by Max Pashkov.
     * As a workaround we use readable() (which uses poll or select())
     * instead of peek_fd() (which uses ioctl FIONREAD). Workaround added
     * 20020604.
     */
    if (PUSH_BACK_PEEK(state) == 0 && vstream_peek(state->stream) <= 0
        && readable(vstream_fileno(state->stream)) <= 0)
        return (0);
    }

    /*
     * Properly terminate the result, and reset the buffer write pointer for
     * reading the next command. This is ugly, but not as ugly as trying to
     * deal with all the early returns below.
     */
    vstring_truncate(state->buffer, VSTRING_LEN(state->buffer) - 2);
    VSTRING_TERMINATE(state->buffer);
    state->data_state = ST_CR_LF;
    VSTRING_RESET(state->buffer);

    /*
     * Got a complete command line. Parse it.
     */
    ptr = vstring_str(state->buffer);
    if (msg_verbose)
    msg_info("%s", ptr);
    if ((command = mystrtok(&ptr, " \t")) == 0) {
    smtp_printf(state->stream, "500 5.5.2 Error: unknown command");
    SMTP_FLUSH(state->stream);
    return (0);
    }
    for (cmdp = command_table; cmdp->name != 0; cmdp++)
    if (strcasecmp(command, cmdp->name) == 0)
        break;
    if (cmdp->name == 0 || (cmdp->flags & FLAG_ENABLE) == 0) {
    smtp_printf(state->stream, "500 5.5.1 Error: unknown command");
    SMTP_FLUSH(state->stream);
    return (0);
    }
    return (command_resp(state, cmdp, command, printable(ptr, '?')));
}

/* read_timeout - handle timer event */

static void read_timeout(int unused_event, void *context)
{
    SINK_STATE *state = (SINK_STATE *) context;

    /*
     * We don't send anything to the client, because we would have to set up
     * an smtp_stream exception handler first. And that is just too much
     * trouble.
     */
    msg_warn("read timeout");
    disconnect(state);
}

/* read_event - handle command or data read events */

static void read_event(int unused_event, void *context)
{
    SINK_STATE *state = (SINK_STATE *) context;

    /*
     * The input reading routine not only reads input (with vstream calls)
     * but also produces output (with smtp_stream calls). Because the output
     * routines can raise timeout or EOF exceptions with vstream_longjmp(),
     * the input reading routine needs to set up corresponding exception
     * handlers with vstream_setjmp(). Guarding the input operations in the
     * same manner is not useful: we must read input in non-blocking mode, so
     * we never get called when the socket stays unreadable too long. And EOF
     * is already trivial to detect with the vstream calls.
     */
    do {
    switch (vstream_setjmp(state->stream)) {

    default:
        msg_panic("unknown read/write error");
        /* NOTREACHED */

    case SMTP_ERR_TIME:
        msg_warn("write timeout");
        disconnect(state);
        return;

    case SMTP_ERR_EOF:
        msg_warn("lost connection");
        disconnect(state);
        return;

    case 0:
        if (state->read_fn(state) < 0) {
        if (msg_verbose)
            msg_info("disconnect");
        disconnect(state);
        return;
        }
    }
    } while (PUSH_BACK_PEEK(state) != 0 || vstream_peek(state->stream) > 0);

    /*
     * Reset the idle timer. Wait until the next input event, or until the
     * idle timer goes off.
     */
    event_request_timer(read_timeout, (void *) state, var_tmout);
}

static void connect_event(int, void *);

/* disconnect - handle disconnection events */

static void disconnect(SINK_STATE *state)
{
    event_disable_readwrite(vstream_fileno(state->stream));
    event_cancel_timer(read_timeout, (void *) state);
    if (show_count) {
    sess_count++;
    do_stats();
    }
    vstream_fclose(state->stream);
    vstring_free(state->buffer);
    /* Clean up file capture attributes. */
    if (state->helo_args)
    myfree(state->helo_args);
    /* Delete incomplete mail transaction. */
    mail_cmd_reset(state);
    if (state->delayed_args)
    myfree(state->delayed_args);
    myfree((void *) state);
    if (max_quit_count > 0 && quit_count >= max_quit_count)
    exit(0);
    if (client_count-- == max_client_count)
    event_enable_read(sock, connect_event, (void *) 0);
}

/* connect_event - handle connection events */

static void connect_event(int unused_event, void *unused_context)
{
    struct sockaddr_storage ss;
    SOCKADDR_SIZE len = sizeof(ss);
    struct sockaddr *sa = (struct sockaddr *) &ss;
    SINK_STATE *state;
    int     fd;

    if ((fd = sane_accept(sock, sa, &len)) >= 0) {
    /* Safety: limit the number of open sockets and capture files. */
    if (++client_count == max_client_count)
        event_disable_readwrite(sock);
    state = (SINK_STATE *) mymalloc(sizeof(*state));
    if (strchr((char *) proto_info->sa_family_list, sa->sa_family))
        SOCKADDR_TO_HOSTADDR(sa, len, &state->client_addr,
                 (MAI_SERVPORT_STR *) 0, sa->sa_family);
    else
        strncpy(state->client_addr.buf, "local", sizeof("local"));
    if (msg_verbose)
        msg_info("connect (%s %s)",
#ifdef AF_LOCAL
             sa->sa_family == AF_LOCAL ? "AF_LOCAL" :
#else
             sa->sa_family == AF_UNIX ? "AF_UNIX" :
#endif
             sa->sa_family == AF_INET ? "AF_INET" :
#ifdef AF_INET6
             sa->sa_family == AF_INET6 ? "AF_INET6" :
#endif
             "unknown protocol family",
             state->client_addr.buf);
    non_blocking(fd, NON_BLOCKING);
    state->stream = vstream_fdopen(fd, O_RDWR);
    vstream_tweak_sock(state->stream);
    state->buffer = vstring_alloc(1024);
    state->read_fn = command_read;
    state->data_state = ST_ANY;
    PUSH_BACK_SET(state, "");
    smtp_timeout_setup(state->stream, var_tmout);
    state->in_mail = 0;
    state->rcpts = 0;
    state->delayed_response = 0;
    state->delayed_args = 0;
    /* Initialize file capture attributes. */
#ifdef AF_INET6
    if (sa->sa_family == AF_INET6)
        state->addr_prefix = "ipv6:";
    else
#endif
        state->addr_prefix = "";

    state->helo_args = 0;
    state->client_proto = enable_lmtp ? "LMTP" : "SMTP";
    state->start_time = 0;
    state->id = 0;
    state->dump_file = 0;

    /*
     * We use the smtp_stream module to produce output. That module
     * throws an exception via vstream_longjmp() in case of a timeout or
     * lost connection error. Therefore we must prepare to handle these
     * exceptions with vstream_setjmp().
     */
    switch (vstream_setjmp(state->stream)) {

    default:
        msg_panic("unknown read/write error");
        /* NOTREACHED */

    case SMTP_ERR_TIME:
        msg_warn("write timeout");
        disconnect(state);
        return;

    case SMTP_ERR_EOF:
        msg_warn("lost connection");
        disconnect(state);
        return;

    case 0:
        if (command_resp(state, command_table, "connect", "") < 0)
        disconnect(state);
        else if (command_table->delay == 0) {
        event_enable_read(fd, read_event, (void *) state);
        event_request_timer(read_timeout, (void *) state, var_tmout);
        }
    }
    }
}

/* usage - explain */

static void usage(char *myname)
{
    msg_fatal("usage: %s [-468acCeEFLpPv] [-A abort_delay] [-b soft_bounce_reply] [-B hard_bounce_reply] [-d dump-template] [-D dump-template] [-f commands] [-h hostname] [-m max_concurrency] [-M message_quit_count] [-n quit_count] [-q commands] [-r commands] [-R root-dir] [-s commands] [-S start-string] [-u user_privs] [-w delay] [host]:port backlog", myname);
}

MAIL_VERSION_STAMP_DECLARE;

int     main(int argc, char **argv)
{
    int     backlog;
    int     ch;
    int     delay;
    const char *protocols = INET_PROTO_NAME_ALL;
    const char *root_dir = 0;
    const char *user_privs = 0;

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

    /*
     * Fix 20051207.
     */
    signal(SIGPIPE, SIG_IGN);

    /*
     * Initialize diagnostics.
     */
    msg_vstream_init(argv[0], VSTREAM_ERR);

    /*
     * Parse JCL.
     */
    while ((ch = GETOPT(argc, argv, "468aA:b:B:cCd:D:eEf:Fh:H:Ln:m:M:NpPq:Q:r:R:s:S:t:T:u:vw:W:")) > 0) {
    switch (ch) {
    case '4':
        protocols = INET_PROTO_NAME_IPV4;
        break;
    case '6':
        protocols = INET_PROTO_NAME_IPV6;
        break;
    case '8':
        disable_8bitmime = 1;
        break;
    case 'a':
        disable_saslauth = 1;
        break;
    case 'A':
        if (!alldig(optarg) || (abort_delay = atoi(optarg)) < 0)
        usage(argv[0]);
        break;
    case 'b':
        if (optarg[0] != '4' || strspn(optarg, "0123456789") != 3) {
        msg_error("bad soft error reply: %s", optarg);
        usage(argv[0]);
        } else
        soft_error_resp = optarg;
        break;
    case 'B':
        if (optarg[0] != '5' || strspn(optarg, "0123456789") != 3) {
        msg_error("bad hard error reply: %s", optarg);
        usage(argv[0]);
        } else
        hard_error_resp = optarg;
        break;
    case 'c':
        show_count++;
        break;
    case 'C':
        disable_xclient = 1;
        reset_cmd_flags("xclient", FLAG_ENABLE);
        break;
    case 'd':
        single_template = optarg;
        break;
    case 'D':
        shared_template = optarg;
        break;
    case 'e':
        disable_esmtp = 1;
        break;
    case 'E':
        disable_enh_status = 1;
        break;
    case 'f':
        set_cmds_flags(optarg, FLAG_HARD_ERR);
        disable_pipelining = 1;
        break;
    case 'F':
        disable_xforward = 1;
        reset_cmd_flags("xforward", FLAG_ENABLE);
        break;
    case 'h':
        var_myhostname = optarg;
        break;
    case 'H':
        if ((data_read_delay = atoi(optarg)) <= 0)
        msg_fatal("bad data read delay: %s", optarg);
        break;
    case 'L':
        enable_lmtp = 1;
        break;
    case 'm':
        if ((max_client_count = atoi(optarg)) <= 0)
        msg_fatal("bad concurrency limit: %s", optarg);
        break;
    case 'M':
        if ((max_msg_quit_count = atoi(optarg)) <= 0)
        msg_fatal("bad message quit count: %s", optarg);
        break;
    case 'n':
        if ((max_quit_count = atoi(optarg)) <= 0)
        msg_fatal("bad quit count: %s", optarg);
        break;
    case 'N':
        disable_dsn = 1;
        break;
    case 'p':
        disable_pipelining = 1;
        break;
    case 'P':
        pretend_pix = 1;
        disable_esmtp = 1;
        break;
    case 'q':
        set_cmds_flags(optarg, FLAG_DISCONNECT);
        break;
    case 'Q':
        set_cmds_flags(optarg, FLAG_CLOSE);
        break;
    case 'r':
        set_cmds_flags(optarg, FLAG_SOFT_ERR);
        disable_pipelining = 1;
        break;
    case 'R':
        root_dir = optarg;
        break;
    case 's':
        openlog(basename(argv[0]), LOG_PID, LOG_MAIL);
        set_cmds_flags(optarg, FLAG_SYSLOG);
        break;
    case 'S':
        start_string = vstring_alloc(10);
        unescape(start_string, optarg);
        break;
    case 't':
        if ((var_tmout = atoi(optarg)) <= 0)
        msg_fatal("bad timeout: %s", optarg);
        break;
    case 'T':
        if ((inet_windowsize = atoi(optarg)) <= 0)
        msg_fatal("bad TCP window size: %s", optarg);
        break;
    case 'u':
        user_privs = optarg;
        break;
    case 'v':
        msg_verbose++;
        break;
    case 'w':
        if ((delay = atoi(optarg)) <= 0)
        usage(argv[0]);
        set_cmd_delay("data", delay, 0);
        break;
    case 'W':
        set_cmd_delay_arg(optarg);
        break;
    default:
        usage(argv[0]);
    }
    }
    if (argc - optind != 2)
    usage(argv[0]);
    if ((backlog = atoi(argv[optind + 1])) <= 0)
    usage(argv[0]);
    if (single_template && shared_template)
    msg_fatal("use only one of -d or -D, but not both");
    if (geteuid() == 0 && user_privs == 0)
    msg_fatal("-u option is required if running as root");

    /*
     * Initialize.
     */
    if (var_myhostname == 0)
    var_myhostname = "smtp-sink";
    set_cmds_flags(enable_lmtp ? "lhlo" :
           disable_esmtp ? "helo" :
           "helo, ehlo", FLAG_ENABLE);
    proto_info = inet_proto_init("protocols", protocols);
    if (strncmp(argv[optind], "unix:", 5) == 0) {
    sock = unix_listen(argv[optind] + 5, backlog, BLOCKING);
    } else {
    if (strncmp(argv[optind], "inet:", 5) == 0)
        argv[optind] += 5;
    sock = inet_listen(argv[optind], backlog, BLOCKING);
    }
    if (user_privs)
    chroot_uid(root_dir, user_privs);

    if (single_template)
    mysrand((int) time((time_t *) 0));
    else if (shared_template)
    single_template = shared_template;

    /*
     * Start the event handler.
     */
    event_enable_read(sock, connect_event, (void *) 0);
    for (;;)
    event_loop(-1);
}