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protocol.c
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/*
* This file is part of libESMTP, a library for submission of RFC 2822
* formatted electronic mail messages using the SMTP protocol described
* in RFC 2821.
*
* Copyright (C) 2001,2002 Brian Stafford <brian@stafford.uklinux.net>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/* The SMTP protocol engine and handler functions for the core SMTP
commands and their extended parameters. Extended commands are mostly
in files of their own. */
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <stdarg.h>
#include <unistd.h>
#include <errno.h>
#include <missing.h> /* declarations for missing library functions */
#include <sys/socket.h>
#if HAVE_LWRES_NETDB_H
# include <lwres/netdb.h>
#elif !HAVE_GETADDRINFO
# include "getaddrinfo.h"
#else
# include <netdb.h>
#endif
#if HAVE_UNAME
#include <sys/utsname.h>
#endif
#include "libesmtp-private.h"
#include "message-source.h"
#include "siobuf.h"
#include "tokens.h"
#include "headers.h"
#include "protocol.h"
struct protocol_states
{
void (*cmd) (siobuf_t conn, smtp_session_t session);
void (*rsp) (siobuf_t conn, smtp_session_t session);
};
/* The following array of state handlers is indexed by the state (!) */
struct protocol_states protocol_states[] =
{
#define S(x) { cmd_##x, rsp_##x, },
#include "protocol-states.h"
};
static int
set_first_recipient (smtp_session_t session)
{
smtp_recipient_t recipient;
if (session->current_message == NULL)
return 0;
for (recipient = session->current_message->recipients;
recipient != NULL;
recipient = recipient->next)
if (!recipient->complete)
break;
session->cmd_recipient = session->rsp_recipient = recipient;
return recipient != NULL;
}
/* Return a pointer to the next unsent recipient. This can't operate
on the session structure directly as the other first/next functions
do since there are two variables for the current recipient due to
the implementation of PIPELINING. */
static smtp_recipient_t
next_recipient (smtp_recipient_t recipient)
{
while ((recipient = recipient->next) != NULL)
if (!recipient->complete)
break;
return recipient;
}
/* Set the session's current message to the next unsent message.
*/
int
next_message (smtp_session_t session)
{
while ((session->current_message = session->current_message->next) != NULL)
if (set_first_recipient (session))
return 1;
return 0;
}
/* Set the current message to the first unsent message in the
session. */
static int
set_first_message (smtp_session_t session)
{
for (session->current_message = session->messages;
session->current_message != NULL;
session->current_message = session->current_message->next)
if (set_first_recipient (session))
return 1;
return 0;
}
/*****************************************************************************
* The main protocol engine.
*****************************************************************************/
int
do_session (smtp_session_t session)
{
struct addrinfo hints, *res, *addrs;
int err;
int sd;
siobuf_t conn;
int nresp, status, want_flush, fast;
char *nodename;
#if HAVE_UNAME
if (session->localhost == NULL)
{
struct utsname name;
if (uname (&name) < 0)
{
set_errno (errno);
return 0;
}
session->localhost = strdup (name.nodename);
if (session->localhost == NULL)
{
set_errno (ENOMEM);
return 0;
}
}
#elif HAVE_GETHOSTNAME
if (session->localhost == NULL)
{
char host[256];
if (gethostname (host, sizeof host) < 0)
{
set_errno (errno);
return 0;
}
session->localhost = strdup (host);
if (session->localhost == NULL)
{
set_errno (ENOMEM);
return 0;
}
}
#endif
/* Initialise the current message and recipient variables in the
session. This returns zero if there is no work to do. */
#ifndef USE_ETRN
if (!set_first_message (session))
#else
if (!set_first_message (session) && session->etrn_nodes == NULL)
#endif
{
set_error (SMTP_ERR_NOTHING_TO_DO);
return 0;
}
/* Create a message source only if it is needed.
*/
if (session->msg_source == NULL && session->current_message != NULL)
{
session->msg_source = msg_source_create ();
if (session->msg_source == NULL)
{
set_errno (ENOMEM);
return 0;
}
}
/* Connect to the SMTP server. The following code will only work for
socket connections at present. This will eventually change to
permit connections on any type of file descriptor, e.g. for LMTP
servers or forking an SMTP server which can run the protocol on
its standard input. */
errno = 0;
nodename = (session->host == NULL || *session->host == '\0') ? NULL
: session->host;
/* Use the RFC 2553/Posix resolver interface. This allows for much
cleaner code, protocol independence and thread safety. */
memset (&hints, 0, sizeof hints);
hints.ai_family = PF_UNSPEC;
hints.ai_socktype = SOCK_STREAM;
err = getaddrinfo (nodename, session->port, &hints, &res);
if (err != 0)
{
set_herror (err);
return 0;
}
/* Try to establish an SMTP session with each host in turn until one
succeeds. */
for (addrs = res; addrs != NULL; addrs = addrs->ai_next)
{
sd = socket (addrs->ai_family, addrs->ai_socktype, addrs->ai_protocol);
if (sd < 0)
{
set_errno (errno);
continue;
}
if (connect (sd, addrs->ai_addr, addrs->ai_addrlen) < 0)
{
/* Failed to connect. Close the socket and try again. */
set_errno (errno);
close (sd);
continue;
}
/* Add buffering to the socket */
conn = sio_attach (sd, sd, SIO_BUFSIZE);
if (conn == NULL)
{
set_errno (ENOMEM);
freeaddrinfo (res);
close (sd);
return 0;
}
/* If monitoring the protocol, pass the callback on to the sio_
package. */
if (session->monitor_cb != NULL)
sio_set_monitorcb (conn, session->monitor_cb, session->monitor_cb_arg);
if (session->event_cb != NULL)
(*session->event_cb) (session, SMTP_EV_CONNECT, session->event_cb_arg);
/* Outer loop of the protocol. This is trickier than superficial
examination of RFC 821 would suggest, however the complexity is
required to handle batched commands and responses. RFC 821 makes
no comment on the underlying transport so it cannot be assumed that
each command and its response is transported in a single packet on
the network or that the network preserves packet boundaries (or,
for that matter, that the underlying transport is even a network,
e.g. it might be a pipe or a AF_UNIX socket). Multiple commands
may be sent in a single packet and similarly multiple responses
may be returned in a single packet. RFC 2920 which describes the
PIPELINING SMTP extension clarifies this for the case where the
underlying transport is TCP/IP.
In this implementation the outer loop will batch together as many
commands as possible until the remote server sends a response (this
will normally happen after the local transmit buffer is flushed)
or a command has been sent which requires a response before the
client can proceed.
In order not to break certain SMTP server implementations, flushing
is done after every command unless the PIPELINING keyword is received
in response to the EHLO command. Even when PIPELINING is in force
certain commands *always* flush the transmit buffer.
One good reason for wanting PIPELINING is that when submitting mail
to an ISP's sluggish server, there will be a big performance boost
since many round trips are eliminated.
As the protocol engine advances through its states, it will walk
through the messages and recipients within the session.
The protocol functions set a few timeouts as they progress. The
values set are those reccommended in RFC 2821.
[is it just me, or does everybody find that it's easier to implement
protocols on the server side?]
*/
/* Reset variables to their initial state before entering the protocol
main loop. */
session->extensions = 0;
session->try_fallback_server = 0;
reset_status (&session->mta_status);
destroy_auth_mechanisms (session);
session->authenticated = 0;
#ifdef USE_TLS
session->using_tls = 0;
#endif
nresp = 0;
session->cmd_state = session->rsp_state = 0;
while (session->rsp_state >= 0)
{
if (session->cmd_state == -1)
session->cmd_state = session->rsp_state;
(*protocol_states[session->cmd_state].cmd) (conn, session);
sio_mark (conn);
if (!(session->extensions & EXT_PIPELINING))
session->cmd_state = -1;
nresp++;
if (session->rsp_state < 0)
break;
/* The following loop polls the server and reads or writes
to it as required.
When the command state is set to -1, this signals that no
more commands can be issued until the response to the most
recent command has been processed, therefore the write
buffer must be explicitly flushed. If the command state is
not -1, more commands may be issued however, pending
responses from the server should be processed. When this
is the case, sio_poll should return immediately if there is
nothing to read. `fast' requests this non-blocking poll.
`want_flush' indicates that the write buffer should be
sent to the server. This flag remains set until the buffer
has been written.
After explicitly flushing the buffer, sio_poll blocks
waiting to read data from the server since the server may
take some time to complete the pending commands.
*/
want_flush = (session->cmd_state == -1);
fast = (session->cmd_state != -1);
while ((status = sio_poll (conn, nresp > 0, want_flush, fast)) > 0)
{
if (status & SIO_READ)
{
nresp--;
/* TODO: change so that the response line is parsed
here. This means that the server 421
response which can be issued at any time may
be checked for here. */
/* When reading from the server in the response state
handlers the read call blocks. Complete responses
must be read from the server before processing and
an individual response may be larger than the read
buffer. */
(*protocol_states[session->rsp_state].rsp) (conn, session);
}
/* XXX - Here I assume that once the write fd becomes
available for writing, it stays that way until
it is written to. I.e. a blocking read() or a
subsequent poll() will not revoke the writable
status. Could somebody confirm that this is the
case? */
if (status & SIO_WRITE)
{
sio_flush (conn);
want_flush = 0;
}
}
if (status < 0)
{
set_error (SMTP_ERR_DROPPED_CONNECTION);
break;
}
}
sio_detach (conn);
close (sd);
if (session->event_cb != NULL)
(*session->event_cb) (session, SMTP_EV_DISCONNECT,
session->event_cb_arg);
/* This flag will be set if the server was reached OK but was the
wrong kind of server or the client is told to go away. So if
not set the protocol must have concluded sucessfully. */
if (!session->try_fallback_server)
{
freeaddrinfo (res);
return 1;
}
}
/* If the loop terminated, couldn't work with any servers. */
freeaddrinfo (res);
return 0;
}
/*****************************************************************************
* Response parser.
*****************************************************************************/
static int
parse_status_triplet (char *p, char **ep, struct smtp_status *triplet)
{
triplet->enh_class = strtol (p, &p, 10);
if (*p++ != '.')
return 0;
triplet->enh_subject = strtol (p, &p, 10);
if (*p++ != '.')
return 0;
triplet->enh_detail = strtol (p, &p, 10);
*ep = p;
return 1;
}
static int
compare_status_triplet (struct smtp_status *a, struct smtp_status *b)
{
return a->enh_class == b->enh_class
&& a->enh_subject == b->enh_subject
&& a->enh_detail == b->enh_detail;
}
/* Free memory allocated in read_smtp_response()
and clear the status structure */
void
reset_status (struct smtp_status *status)
{
if (status->text != NULL)
free ((void *) status->text);
memset (status, 0, sizeof (struct smtp_status));
}
/* All SMTP responses have standard syntax. This function could be
called by the protocol engine above and the results from the parsed
response passed to the response handler functions. However certain
commands involve extra intermediate exchanges with the server that
may not correspond to the standard syntax. The response handlers
must therefore call this function themselves. */
int
read_smtp_response (siobuf_t conn, smtp_session_t session,
struct smtp_status *status,
int (*cb) (smtp_session_t, char *))
{
struct catbuf text;
char buf[1024];
char *p, *nul;
int code, more, want_enhanced, textlen, quit_now;
struct smtp_status triplet;
/* First line of an SMTP response is the normal one. Put it in a buffer.
Save the status code and the enhanced status triplet if ENHSTATUSCODES
is set. The remainder of the line is the message from the server.
If there are any continuation lines, get the status code and enhanced
status triplet and check that they are the same as the first response
line. If not there is a protocol error. Process the extra lines
by calling a callback. If not supplied, concatenate the lines
(excluding the status info) with the first line. */
reset_status (status);
if ((p = sio_gets (conn, buf, sizeof buf)) == NULL)
{
set_error (SMTP_ERR_DROPPED_CONNECTION);
return -1;
}
status->code = strtol (p, &p, 10);
if (!(*p == ' ' || *p == '-'))
{
set_error (SMTP_ERR_INVALID_RESPONSE_SYNTAX);
return -1;
}
more = *p++ == '-';
/* RFC 2034 states that only 2xx, 4xx and 5xx responses are accompanied
by enhanced status codes. */
code = status->code / 100;
want_enhanced = (session->extensions & EXT_ENHANCEDSTATUSCODES);
if (code != 2 && code != 4 && code != 5)
want_enhanced = 0;
if (want_enhanced && !parse_status_triplet (p, &p, status))
{
quit_now = 0; /* Be tolerant by default */
if (session->event_cb != NULL)
(*session->event_cb) (session, SMTP_EV_SYNTAXWARNING,
session->event_cb_arg, &quit_now);
if (quit_now)
{
set_error (SMTP_ERR_INVALID_RESPONSE_SYNTAX);
return -1;
}
want_enhanced = 0;
}
while (isspace (*p))
p++;
/* p points to the remainder of the line. This is the text of the
server message */
cat_init (&text, 128);
concatenate (&text, p, -1);
while (more)
{
if ((p = sio_gets (conn, buf, sizeof buf)) == NULL)
{
cat_free (&text);
set_error (SMTP_ERR_DROPPED_CONNECTION);
return -1;
}
code = strtol (p, &p, 10);
if (code != status->code)
{
cat_free (&text);
set_error (SMTP_ERR_STATUS_MISMATCH);
return -1;
}
if (!(*p == ' ' || *p == '-'))
{
cat_free (&text);
set_error (SMTP_ERR_INVALID_RESPONSE_SYNTAX);
return -1;
}
more = *p++ == '-';
if (want_enhanced)
{
if (!parse_status_triplet (p, &p, &triplet))
{
cat_free (&text);
set_error (SMTP_ERR_INVALID_RESPONSE_SYNTAX);
return -1;
}
if (!compare_status_triplet (status, &triplet))
{
cat_free (&text);
set_error (SMTP_ERR_STATUS_MISMATCH);
return -1;
}
}
/* Skip whitespace but don't wander over the CRLF */
while (isspace (*p) && isprint (*p))
p++;
/* Check that the line is correctly terminated. */
nul = strchr (p, '\0');
if (nul == NULL || nul == p || nul[-1] != '\n')
{
cat_free (&text);
set_error (SMTP_ERR_UNTERMINATED_RESPONSE);
return -1;
}
/* `p' points to the remainder of the line. Either process with the
callback or concatenate with the first line. */
if (cb != NULL)
(*cb) (session, p);
else
concatenate (&text, p, nul - p);
/* Check if the total text returned in a multiline response
exceeds 4k. Abort if this happens, this might be a DoS attack
or a broken server. */
textlen = 0;
cat_buffer (&text, &textlen);
if (textlen > 4096)
{
cat_free (&text);
set_error (SMTP_ERR_UNTERMINATED_RESPONSE);
return -1;
}
}
/* Terminate and save the response text */
concatenate (&text, "", 1);
status->text = cat_shrink (&text, NULL);
return status->code / 100;
}
/*****************************************************************************
* Command and response handlers. Return value is the next send/response
* state. If a cmd_xxxx() function returns -1, the response determines
* the next state, implying that a flush is needed.
*****************************************************************************/
/*****************************************************************************
* Server Greeting
*****************************************************************************/
/* If the response to the server greeting is not a 2xx status code,
issue the QUIT command and terminate the session. */
void
cmd_greeting (siobuf_t conn, smtp_session_t session)
{
/* Set a five minute timeout. */
sio_set_timeout (conn, session->greeting_timeout);
session->cmd_state = -1;
}
void
rsp_greeting (siobuf_t conn, smtp_session_t session)
{
int code;
code = read_smtp_response (conn, session, &session->mta_status, NULL);
if (code == 2 && session->mta_status.code == 220)
session->rsp_state = S_ehlo;
else if (code == 4 || code == 5)
{
session->rsp_state = S_quit; /* Graceful exit using QUIT */
session->try_fallback_server = 1;
}
else
{
session->rsp_state = -1; /* Drop the connection and run */
session->try_fallback_server = 1;
}
/* TODO: certain broken servers may break when the EHLO command is
issued. For example, one known behaviour is to close the
connection after returning the 501 response. This is wrong
but it happens.
An API option is needed to avoid using EHLO!
*/
}
/*****************************************************************************
* EHLO
*****************************************************************************/
/* EHLO is the preferred client greeting to the server. The parameter is
the FQDN of the client host. The server response is the greeting line
followed by extra lines listing the server capabilities. The additional
lines are parsed and set the session capability flags. If the response
is "501 command not implemented", the HELO command should be used instead.
Since the next command issued depends on the server response the output
must be flushed.
Next state is one of Auth, Helo, Mail.
*/
void
cmd_ehlo (siobuf_t conn, smtp_session_t session)
{
sio_printf (conn, "EHLO %s\r\n", session->localhost);
session->cmd_state = -1;
}
#define no_required_extension(s,e) \
(((s)->required_extensions & (e)) && !((s)->extensions & (e)))
static int
report_extensions (smtp_session_t session)
{
int quit_now;
unsigned long exts = 0;
/* Report extensions that are required but not available.
*/
if (no_required_extension (session, EXT_DSN))
{
quit_now = 0;
if (session->event_cb != NULL)
(*session->event_cb) (session, SMTP_EV_EXTNA_DSN,
session->event_cb_arg, &quit_now);
if (quit_now)
exts |= EXT_DSN;
}
#ifdef USE_CHUNKING
if (no_required_extension (session, EXT_CHUNKING))
{
quit_now = 0;
if (session->event_cb != NULL)
(*session->event_cb) (session, SMTP_EV_EXTNA_CHUNKING,
session->event_cb_arg, &quit_now);
if (quit_now)
exts |= EXT_CHUNKING;
}
if (no_required_extension (session, EXT_BINARYMIME))
{
if (session->event_cb != NULL)
(*session->event_cb) (session, SMTP_EV_EXTNA_BINARYMIME,
session->event_cb_arg);
exts |= EXT_BINARYMIME;
}
#endif
if (no_required_extension (session, EXT_8BITMIME))
{
if (session->event_cb != NULL)
(*session->event_cb) (session, SMTP_EV_EXTNA_8BITMIME,
session->event_cb_arg);
exts |= EXT_8BITMIME;
}
#ifdef USE_ETRN
if (no_required_extension (session, EXT_ETRN))
{
quit_now = 1;
if (session->event_cb != NULL)
(*session->event_cb) (session, SMTP_EV_EXTNA_ETRN,
session->event_cb_arg, &quit_now);
if (quit_now)
exts |= EXT_ETRN;
}
#endif
return !exts;
}
static int
cb_ehlo (smtp_session_t session, char *buf)
{
const char *p;
char token[32];
if (!read_atom (skipblank (buf), &p, token, sizeof token))
{
/* expecting an atom - do nothing */
return 0;
}
/* Since the session structure mostly just carries a bit for each of
the extensions, there is no point #ifdefing out the extension
keywords for omitted features. Also extensions may be added
in the future so it is not an error to have an unrecognised
extension keyword. */
if (strcasecmp (token, "ENHANCEDSTATUSCODES") == 0) /* RFC 1893, RFC 2034 */
session->extensions |= EXT_ENHANCEDSTATUSCODES;
else if (strcasecmp (token, "PIPELINING") == 0) /* RFC 2920 */
session->extensions |= EXT_PIPELINING;
else if (strcasecmp (token, "DSN") == 0) /* RFC 1891 */
session->extensions |= EXT_DSN;
else if (strcasecmp (token, "AUTH") == 0) /* RFC 2554 */
{
session->extensions |= EXT_AUTH;
set_auth_mechanisms (session, p);
}
#ifdef AUTH_ID_HACK
else if (strncasecmp (token, "AUTH=", 5) == 0) /* non-standard syntax */
{
session->extensions |= EXT_AUTH;
set_auth_mechanisms (session, token + 5);
set_auth_mechanisms (session, p);
}
#endif
else if (strcasecmp (token, "STARTTLS") == 0) /* RFC 3207 */
session->extensions |= EXT_STARTTLS;
else if (strcasecmp (token, "SIZE") == 0) /* RFC 1870 */
{
session->extensions |= EXT_SIZE;
session->size_limit = strtol (p, NULL, 10);
}
else if (strcasecmp (token, "CHUNKING") == 0) /* RFC 3030 */
session->extensions |= EXT_CHUNKING;
else if (strcasecmp (token, "BINARYMIME") == 0) /* RFC 3030 */
session->extensions |= EXT_BINARYMIME;
else if (strcasecmp (token, "8BITMIME") == 0) /* RFC 1652 */
session->extensions |= EXT_8BITMIME;
else if (strcasecmp (token, "DELIVERBY") == 0) /* RFC 2852 */
{
session->extensions |= EXT_DELIVERBY;
session->min_by_time = strtol (p, NULL, 10);
}
else if (strcasecmp (token, "ETRN") == 0) /* RFC 1985 */
session->extensions |= EXT_ETRN;
else if (strcasecmp (token, "XUSR") == 0) /* sendmail (I feel ill) */
session->extensions |= EXT_XUSR;
else if (strcasecmp (token, "XEXCH50") == 0) /* exchange (I feel worse) */
session->extensions |= EXT_XEXCH50;
return 1;
}
void
rsp_ehlo (siobuf_t conn, smtp_session_t session)
{
int code;
session->extensions = 0;
destroy_auth_mechanisms (session);
code = read_smtp_response (conn, session, &session->mta_status, cb_ehlo);
if (code < 0)
{
session->rsp_state = S_quit;
return;
}
if (code != 2)
session->extensions = 0;
if (code == 4)
{
/* 4xx failure code. Something is temporarily wrong. Fail the
entire session and let the application retry later. */
session->rsp_state = S_quit;
session->try_fallback_server = 1;
return;
}
else if (code == 5)
{
/* 5xx failure code. Something is permanently wrong. There are
a number of codes indicating that HELO is worth a try since
the server did not understand EHLO. Otherwise fail the entire
session. The application must correct something and retry later. */
if (session->mta_status.code == 500 || session->mta_status.code == 501
|| session->mta_status.code == 502 || session->mta_status.code == 504)
session->rsp_state = S_helo;
else
session->rsp_state = S_quit;
return;
}
else if (code != 2)
{
/* Response must be 2xx, 4xx or 5xx */
set_error (SMTP_ERR_INVALID_RESPONSE_STATUS);
session->rsp_state = S_quit;
return;
}
#ifdef USE_TLS
/* Totally ignore the TLS stuff if it's already in use */
if (!session->using_tls && session->starttls_enabled != Starttls_DISABLED)
{
if (select_starttls (session))
{
session->rsp_state = S_starttls;
return;
}
if (session->starttls_enabled == Starttls_REQUIRED)
{
if (session->event_cb != NULL)
(*session->event_cb) (session, SMTP_EV_EXTNA_STARTTLS,
session->event_cb_arg, NULL);
session->rsp_state = S_quit;
set_error (SMTP_ERR_EXTENSION_NOT_AVAILABLE);
return;
}
}
#endif
/* If AUTH is enabled but no mechanisms can be selected, move on to the
MAIL command since the MTA is required to accept mail for its own
domain. */
if ((session->extensions & EXT_AUTH) && select_auth_mechanism (session))
{
session->rsp_state = S_auth;
return;
}
/* Report extensions *after* starting TLS or doing AUTH since either
of these can restart the session with different SMTP extensions
being offered by the server. */
if (!report_extensions (session))
{
set_error (SMTP_ERR_EXTENSION_NOT_AVAILABLE);
session->rsp_state = S_quit;
return;
}
#ifdef USE_ETRN
session->rsp_state = check_etrn (session)
? S_etrn : initial_transaction_state (session);
#else
session->rsp_state = initial_transaction_state (session);
#endif
}
/* Select the correct initial state after reading the EHLO response or
after DATA or RSET in the previous transaction. */
int
initial_transaction_state (smtp_session_t session)
{
#ifdef USE_XUSR
if (session->extensions & EXT_XUSR)
return S_xusr;
#endif
return S_mail;
}
/*****************************************************************************
* HELO
*****************************************************************************/
/* HELO is absolutely *not* the preferred client greeting to the server.
The parameter is the FQDN of the client host. The server response is
the greeting line. No capabilities are reported so all extensions
are turned off.
Next state is Mail.
*/
void
cmd_helo (siobuf_t conn, smtp_session_t session)
{
sio_printf (conn, "HELO %s\r\n", session->localhost);
session->cmd_state = -1;
}
void
rsp_helo (siobuf_t conn, smtp_session_t session)
{
int code;
#ifdef USE_TLS
int notls;
#endif
session->extensions = 0;
destroy_auth_mechanisms (session);
code = read_smtp_response (conn, session, &session->mta_status, NULL);
if (code < 0)
{
session->try_fallback_server = 1;
session->rsp_state = S_quit;
return;
}
if (code != 2)
{
if (code != 4 || code != 5)
set_error (SMTP_ERR_INVALID_RESPONSE_STATUS);
session->try_fallback_server = 1;
session->rsp_state = S_quit;
return;
}
#ifdef USE_TLS
/* Care must be taken when checking for required TLS. The client may
have connected to a tunnel which offers the STARTTLS extension and
the real server does not implement SMTP extensions. Hence the
check that TLS is actually in use before reporting that the
extension is not available. */
notls = !session->using_tls && session->starttls_enabled == Starttls_REQUIRED;
if (notls && session->event_cb != NULL)
(*session->event_cb) (session, SMTP_EV_EXTNA_STARTTLS,
session->event_cb_arg, NULL);
#else
# define notls 0
#endif
/* There are no extensions. Make sure none were required. */
if (!report_extensions (session) || notls)
{
set_error (SMTP_ERR_EXTENSION_NOT_AVAILABLE);
session->rsp_state = S_quit;
return;
}
/* Unlike EHLO, the only next state can be Mail, since there are
no extensions to check for message acceptability or options to set
before proceeding. */
session->rsp_state = initial_transaction_state (session);
}
/*****************************************************************************
* MAIL FROM:
*****************************************************************************/
/* MAIL FROM: is the first step in sending a message. Select the first
or a subsequent message from the session structure. The message sender
is taken from the message structure.
Next state is always Rcpt, therefore this command need not be flushed.
*/
void
cmd_mail (siobuf_t conn, smtp_session_t session)
{
const char *mailbox;
smtp_message_t message;
char xtext[256];
/* Set a five minute timeout. This stays in force until the DATA
command. */
sio_set_timeout (conn, session->envelope_timeout);
message = session->current_message;
mailbox = message->reverse_path_mailbox;
sio_printf (conn, "MAIL FROM:<%s>", (mailbox != NULL) ? mailbox : "");
/* SIZE: SIZE=message-size-estimate */
if ((session->extensions & EXT_SIZE) && message->size_estimate > 0)
sio_printf (conn, " SIZE=%lu", message->size_estimate);
/* DSN: RET=FULL/HDRS ENVID=xtext */
if (session->extensions & EXT_DSN)
{
static const char *ret[] = { NULL, "FULL", "HDRS" };
if (message->dsn_ret != Ret_NOTSET)
sio_printf (conn, " RET=%s", ret[message->dsn_ret]);
if (message->dsn_envid != NULL)
sio_printf (conn, " ENVID=%s",
encode_xtext (xtext, sizeof xtext, message->dsn_envid));
}
/* 8BITMIME: BODY=7BIT/8BITMIME/BINARYMIME */
#ifdef USE_CHUNKING
if ((session->extensions & (EXT_8BITMIME | EXT_BINARYMIME))
#else