void smtp_chat_cmd(SMTP_SESSION *session, const char *fmt,...)
{
va_list ap;
/*
* Format the command, and update the transaction log.
*/
va_start(ap, fmt);
vstring_vsprintf(session->buffer, fmt, ap);
va_end(ap);
smtp_chat_append(session, "Out: ", STR(session->buffer));
/*
* Optionally log the command first, so we can see in the log what the
* program is trying to do.
*/
if (msg_verbose)
msg_info("> %s: %s", session->namaddrport, STR(session->buffer));
/*
* Send the command to the SMTP server.
*/
smtp_fputs(STR(session->buffer), LEN(session->buffer), session->stream);
/*
* Force flushing of output does not belong here. It is done in the
* smtp_loop() main protocol loop when reading the server response, and
* in smtp_helo() when reading the EHLO response after sending the EHLO
* command.
*
* If we do forced flush here, then we must longjmp() on error, and a
* matching "prepare for disaster" error handler must be set up before
* every smtp_chat_cmd() call.
*/
#if 0
/*
* Flush unsent data to avoid timeouts after slow DNS lookups.
*/
if (time((time_t *) 0) - vstream_ftime(session->stream) > 10)
vstream_fflush(session->stream);
/*
* Abort immediately if the connection is broken.
*/
if (vstream_ftimeout(session->stream))
vstream_longjmp(session->stream, SMTP_ERR_TIME);
if (vstream_ferror(session->stream))
vstream_longjmp(session->stream, SMTP_ERR_EOF);
#endif
}
void smtpd_chat_query(SMTPD_STATE *state)
{
int last_char;
last_char = smtp_get(state->buffer, state->client, var_line_limit);
smtp_chat_append(state, "In: ");
if (last_char != '\n')
msg_warn("%s[%s]: request longer than %d: %.30s...",
state->name, state->addr, var_line_limit,
printable(STR(state->buffer), '?'));
if (msg_verbose)
msg_info("< %s[%s]: %s", state->name, state->addr, STR(state->buffer));
}
void smtpd_chat_reply(SMTPD_STATE *state, char *format,...)
{
va_list ap;
int delay = 0;
va_start(ap, format);
vstring_vsprintf(state->buffer, format, ap);
va_end(ap);
if (var_soft_bounce && STR(state->buffer)[0] == '5')
STR(state->buffer)[0] = '4';
smtp_chat_append(state, "Out: ");
if (msg_verbose)
msg_info("> %s[%s]: %s", state->name, state->addr, STR(state->buffer));
/*
* 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);
smtp_fputs(STR(state->buffer), LEN(state->buffer), state->client);
/*
* 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);
}
SMTP_RESP *smtp_chat_resp(SMTP_SESSION *session)
{
static SMTP_RESP rdata;
char *cp;
int last_char;
int three_digs = 0;
size_t len;
const char *new_reply;
int chat_append_flag;
int chat_append_skipped = 0;
/*
* Initialize the response data buffer.
*/
if (rdata.str_buf == 0) {
rdata.dsn_buf = vstring_alloc(10);
rdata.str_buf = vstring_alloc(100);
}
/*
* Censor out non-printable characters in server responses. Concatenate
* multi-line server responses. Separate the status code from the text.
* Leave further parsing up to the application.
*
* We can't parse or store input that exceeds var_line_limit, so we just
* skip over it to simplify the remainder of the code below.
*/
VSTRING_RESET(rdata.str_buf);
for (;;) {
last_char = smtp_get(session->buffer, session->stream, var_line_limit,
SMTP_GET_FLAG_SKIP);
/* XXX Update the per-line time limit. */
printable(STR(session->buffer), '?');
if (last_char != '\n')
msg_warn("%s: response longer than %d: %.30s...",
session->namaddrport, var_line_limit, STR(session->buffer));
if (msg_verbose)
msg_info("< %s: %.100s", session->namaddrport, STR(session->buffer));
/*
* Defend against a denial of service attack by limiting the amount
* of multi-line text that we are willing to store.
*/
chat_append_flag = (LEN(rdata.str_buf) < var_line_limit);
if (chat_append_flag)
smtp_chat_append(session, "In: ", STR(session->buffer));
else {
if (chat_append_skipped == 0)
msg_warn("%s: multi-line response longer than %d %.30s...",
session->namaddrport, var_line_limit, STR(rdata.str_buf));
if (chat_append_skipped < INT_MAX)
chat_append_skipped++;
}
/*
* Server reply substitution, for fault-injection testing, or for
* working around broken systems. Use with care.
*/
if (smtp_chat_resp_filter != 0) {
new_reply = dict_get(smtp_chat_resp_filter, STR(session->buffer));
if (new_reply != 0) {
msg_info("%s: replacing server reply \"%s\" with \"%s\"",
session->namaddrport, STR(session->buffer), new_reply);
vstring_strcpy(session->buffer, new_reply);
if (chat_append_flag) {
smtp_chat_append(session, "Replaced-by: ", "");
smtp_chat_append(session, " ", new_reply);
}
} else if (smtp_chat_resp_filter->error != 0) {
msg_warn("%s: table %s:%s lookup error for %s",
session->state->request->queue_id,
smtp_chat_resp_filter->type,
smtp_chat_resp_filter->name,
printable(STR(session->buffer), '?'));
vstream_longjmp(session->stream, SMTP_ERR_DATA);
}
}
if (chat_append_flag) {
if (LEN(rdata.str_buf))
VSTRING_ADDCH(rdata.str_buf, '\n');
vstring_strcat(rdata.str_buf, STR(session->buffer));
}
/*
* Parse into code and text. Do not ignore garbage (see below).
*/
for (cp = STR(session->buffer); *cp && ISDIGIT(*cp); cp++)
/* void */ ;
if ((three_digs = (cp - STR(session->buffer) == 3)) != 0) {
if (*cp == '-')
continue;
if (*cp == ' ' || *cp == 0)
break;
}
/*
* XXX Do not simply ignore garbage in the server reply when ESMTP
* command pipelining is turned on. For example, after sending
* ".<CR><LF>QUIT<CR><LF>" and receiving garbage followed by a
* legitimate 2XX reply, Postfix recognizes the server's QUIT reply
* as the END-OF-DATA reply after garbage, causing mail to be lost.
*
* Without the ability to store per-domain status information in queue
* files, automatic workarounds are problematic:
*
* - Automatically deferring delivery creates a "repeated delivery"
* problem when garbage arrives after the DATA stage. Without the
* workaround, Postfix delivers only once.
*
* - Automatically deferring delivery creates a "no delivery" problem
* when the garbage arrives before the DATA stage. Without the
* workaround, mail might still get through.
*
* - Automatically turning off pipelining for delayed mail affects
* deliveries to correctly implemented servers, and may also affect
* delivery of large mailing lists.
*
* So we leave the decision with the administrator, but we don't force
* them to take action, like we would with automatic deferral. If
* loss of mail is not acceptable then they can turn off pipelining
* for specific sites, or they can turn off pipelining globally when
* they find that there are just too many broken sites.
*/
session->error_mask |= MAIL_ERROR_PROTOCOL;
if (session->features & SMTP_FEATURE_PIPELINING) {
msg_warn("%s: non-%s response from %s: %.100s",
session->state->request->queue_id,
smtp_mode ? "ESMTP" : "LMTP",
session->namaddrport, STR(session->buffer));
if (var_helpful_warnings)
msg_warn("to prevent loss of mail, turn off command pipelining "
"for %s with the %s parameter",
STR(session->iterator->addr),
VAR_LMTP_SMTP(EHLO_DIS_MAPS));
}
}
/*
* Extract RFC 821 reply code and RFC 2034 detail. Use a default detail
* code if none was given.
*
* Ignore out-of-protocol enhanced status codes: codes that accompany 3XX
* replies, or codes whose initial digit is out of sync with the reply
* code.
*
* XXX Potential stability problem. In order to save memory, the queue
* manager stores DSNs in a compact manner:
*
* - empty strings are represented by null pointers,
*
* - the status and reason are required to be non-empty.
*
* Other Postfix daemons inherit this behavior, because they use the same
* DSN support code. This means that everything that receives DSNs must
* cope with null pointers for the optional DSN attributes, and that
* everything that provides DSN information must provide a non-empty
* status and reason, otherwise the DSN support code wil panic().
*
* Thus, when the remote server sends a malformed reply (or 3XX out of
* context) we should not panic() in DSN_COPY() just because we don't
* have a status. Robustness suggests that we supply a status here, and
* that we leave it up to the down-stream code to override the
* server-supplied status in case of an error we can't detect here, such
* as an out-of-order server reply.
*/
VSTRING_TERMINATE(rdata.str_buf);
vstring_strcpy(rdata.dsn_buf, "5.5.0"); /* SAFETY! protocol error */
if (three_digs != 0) {
rdata.code = atoi(STR(session->buffer));
if (strchr("245", STR(session->buffer)[0]) != 0) {
for (cp = STR(session->buffer) + 4; *cp == ' '; cp++)
/* void */ ;
if ((len = dsn_valid(cp)) > 0 && *cp == *STR(session->buffer)) {
vstring_strncpy(rdata.dsn_buf, cp, len);
} else {
vstring_strcpy(rdata.dsn_buf, "0.0.0");
STR(rdata.dsn_buf)[0] = STR(session->buffer)[0];
}
}
} else {
rdata.code = 0;
}
rdata.dsn = STR(rdata.dsn_buf);
rdata.str = STR(rdata.str_buf);
return (&rdata);
}
