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/*++
/* NAME
/* smtpd_chat 3
/* SUMMARY
/* SMTP server request/response support
/* SYNOPSIS
/* #include <smtpd.h>
/* #include <smtpd_chat.h>
/*
/* void smtpd_chat_query(state)
/* SMTPD_STATE *state;
/*
/* void smtpd_chat_reply(state, format, ...)
/* SMTPD_STATE *state;
/* char *format;
/*
/* void smtpd_chat_notify(state)
/* SMTPD_STATE *state;
/*
/* void smtpd_chat_reset(state)
/* SMTPD_STATE *state;
/* DESCRIPTION
/* This module implements SMTP server support for request/reply
/* conversations, and maintains a limited SMTP transaction log.
/*
/* smtpd_chat_query() receives a client request and appends a copy
/* to the SMTP transaction log.
/*
/* smtpd_chat_reply() formats a server reply, sends it to the
/* client, and appends a copy to the SMTP transaction log.
/* When soft_bounce is enabled, all 5xx (reject) responses are
/* replaced by 4xx (try again). In case of a 421 reply the
/* SMTPD_FLAG_HANGUP flag is set for orderly disconnect.
/*
/* smtpd_chat_notify() sends a copy of the SMTP transaction log
/* to the postmaster for review. The postmaster notice is sent only
/* when delivery is possible immediately. It is an error to call
/* smtpd_chat_notify() when no SMTP transaction log exists.
/*
/* smtpd_chat_reset() resets the transaction log. This is
/* typically done at the beginning of an SMTP session, or
/* within a session to discard non-error information.
/* DIAGNOSTICS
/* Panic: interface violations. Fatal errors: out of memory.
/* internal protocol errors.
/* 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
/*--*/
/* System library. */
#include <sys_defs.h>
#include <setjmp.h>
#include <unistd.h>
#include <time.h>
#include <stdlib.h> /* 44BSD stdarg.h uses abort() */
#include <stdarg.h>
/* Utility library. */
#include <msg.h>
#include <argv.h>
#include <vstring.h>
#include <vstream.h>
#include <stringops.h>
#include <line_wrap.h>
#include <mymalloc.h>
/* Global library. */
#include <smtp_stream.h>
#include <record.h>
#include <rec_type.h>
#include <mail_proto.h>
#include <mail_params.h>
#include <mail_addr.h>
#include <post_mail.h>
#include <mail_error.h>
#include <smtp_reply_footer.h>
/* Application-specific. */
#include "smtpd.h"
#include "smtpd_expand.h"
#include "smtpd_chat.h"
#define STR vstring_str
#define LEN VSTRING_LEN
/* smtp_chat_reset - reset SMTP transaction log */
void smtpd_chat_reset(SMTPD_STATE *state)
{
if (state->history) {
argv_free(state->history);
state->history = 0;
}
}
/* smtp_chat_append - append record to SMTP transaction log */
static void smtp_chat_append(SMTPD_STATE *state, char *direction,
const char *text)
{
char *line;
if (state->notify_mask == 0)
return;
if (state->history == 0)
state->history = argv_alloc(10);
line = concatenate(direction, text, (char *) 0);
argv_add(state->history, line, (char *) 0);
myfree(line);
}
/* smtpd_chat_query - receive and record an SMTP request */
void smtpd_chat_query(SMTPD_STATE *state)
{
int last_char;
/*
* We can't parse or store input that exceeds var_line_limit, so we skip
* over it to avoid loss of synchronization.
*/
last_char = smtp_get(state->buffer, state->client, var_line_limit,
SMTP_GET_FLAG_SKIP);
smtp_chat_append(state, "In: ", STR(state->buffer));
if (last_char != '\n')
msg_warn("%s: request longer than %d: %.30s...",
state->namaddr, var_line_limit,
printable(STR(state->buffer), '?'));
if (msg_verbose)
msg_info("< %s: %s", state->namaddr, STR(state->buffer));
}
/* smtpd_chat_reply - format, send and record an SMTP response */
void smtpd_chat_reply(SMTPD_STATE *state, const char *format,...)
{
va_list ap;
int delay = 0;
char *cp;
char *next;
char *end;
/*
* Slow down clients that make errors. Sleep-on-anything slows down
* clients that make an excessive number of errors within a session.
*/
if (state->error_count >= var_smtpd_soft_erlim)
sleep(delay = var_smtpd_err_sleep);
va_start(ap, format);
vstring_vsprintf(state->buffer, format, ap);
va_end(ap);
if (*var_smtpd_rej_footer
&& (*(cp = STR(state->buffer)) == '4' || *cp == '5'))
smtp_reply_footer(state->buffer, 0, var_smtpd_rej_footer,
STR(smtpd_expand_filter), smtpd_expand_lookup,
(void *) state);
/* All 5xx replies must have a 5.xx.xx detail code. */
for (cp = STR(state->buffer), end = cp + strlen(STR(state->buffer));;) {
if (var_soft_bounce) {
if (cp[0] == '5') {
cp[0] = '4';
if (cp[4] == '5')
cp[4] = '4';
}
}
/* This is why we use strlen() above instead of VSTRING_LEN(). */
if ((next = strstr(cp, "\r\n")) != 0) {
*next = 0;
if (next[2] != 0)
cp[3] = '-'; /* contact footer kludge */
else
next = end; /* strip trailing \r\n */
} else {
next = end;
}
smtp_chat_append(state, "Out: ", cp);
if (msg_verbose)
msg_info("> %s: %s", state->namaddr, cp);
smtp_fputs(cp, next - cp, state->client);
if (next < end)
cp = next + 2;
else
break;
}
/*
* Flush unsent output if no I/O happened for a while. This avoids
* timeouts with pipelined SMTP sessions that have lots of server-side
* delays (tarpit delays or DNS lookups for UCE restrictions).
*/
if (delay || time((time_t *) 0) - vstream_ftime(state->client) > 10)
vstream_fflush(state->client);
/*
* Abort immediately if the connection is broken.
*/
if (vstream_ftimeout(state->client))
vstream_longjmp(state->client, SMTP_ERR_TIME);
if (vstream_ferror(state->client))
vstream_longjmp(state->client, SMTP_ERR_EOF);
/*
* Orderly disconnect in case of 421 or 521 reply.
*/
if (strncmp(STR(state->buffer), "421", 3) == 0
|| strncmp(STR(state->buffer), "521", 3) == 0)
state->flags |= SMTPD_FLAG_HANGUP;
}
/* print_line - line_wrap callback */
static void print_line(const char *str, int len, int indent, void *context)
{
VSTREAM *notice = (VSTREAM *) context;
post_mail_fprintf(notice, " %*s%.*s", indent, "", len, str);
}
/* smtpd_chat_notify - notify postmaster */
void smtpd_chat_notify(SMTPD_STATE *state)
{
const char *myname = "smtpd_chat_notify";
VSTREAM *notice;
char **cpp;
/*
* Sanity checks.
*/
if (state->history == 0)
msg_panic("%s: no conversation history", myname);
if (msg_verbose)
msg_info("%s: notify postmaster", myname);
/*
* Construct a message for the postmaster, explaining what this is all
* about. This is junk mail: don't send it when the mail posting service
* is unavailable, and use the double bounce sender address to prevent
* mail bounce wars. Always prepend one space to message content that we
* generate from untrusted data.
*/
#define NULL_TRACE_FLAGS 0
#define NO_QUEUE_ID ((VSTRING *) 0)
#define LENGTH 78
#define INDENT 4
notice = post_mail_fopen_nowait(mail_addr_double_bounce(),
var_error_rcpt,
MAIL_SRC_MASK_NOTIFY, NULL_TRACE_FLAGS,
SMTPUTF8_FLAG_NONE, NO_QUEUE_ID);
if (notice == 0) {
msg_warn("postmaster notify: %m");
return;
}
post_mail_fprintf(notice, "From: %s (Mail Delivery System)",
mail_addr_mail_daemon());
post_mail_fprintf(notice, "To: %s (Postmaster)", var_error_rcpt);
post_mail_fprintf(notice, "Subject: %s SMTP server: errors from %s",
var_mail_name, state->namaddr);
post_mail_fputs(notice, "");
post_mail_fputs(notice, "Transcript of session follows.");
post_mail_fputs(notice, "");
argv_terminate(state->history);
for (cpp = state->history->argv; *cpp; cpp++)
line_wrap(printable(*cpp, '?'), LENGTH, INDENT, print_line,
(void *) notice);
post_mail_fputs(notice, "");
if (state->reason)
post_mail_fprintf(notice, "Session aborted, reason: %s", state->reason);
post_mail_fputs(notice, "");
post_mail_fprintf(notice, "For other details, see the local mail logfile");
(void) post_mail_fclose(notice);
}