static void psc_service(VSTREAM *smtp_client_stream,
char *unused_service,
char **unused_argv)
{
const char *myname = "psc_service";
PSC_STATE *state;
struct sockaddr_storage addr_storage;
SOCKADDR_SIZE addr_storage_len = sizeof(addr_storage);
MAI_HOSTADDR_STR smtp_client_addr;
MAI_SERVPORT_STR smtp_client_port;
MAI_HOSTADDR_STR smtp_server_addr;
MAI_SERVPORT_STR smtp_server_port;
int aierr;
const char *stamp_str;
int saved_flags;
/*
* For sanity, require that at least one of INET or INET6 is enabled.
* Otherwise, we can't look up interface information, and we can't
* convert names or addresses.
*/
if (inet_proto_info()->ai_family_list[0] == 0)
msg_fatal("all network protocols are disabled (%s = %s)",
VAR_INET_PROTOCOLS, var_inet_protocols);
/*
* This program handles all incoming connections, so it must not block.
* We use event-driven code for all operations that introduce latency.
*
* Note: instead of using VSTREAM-level timeouts, we enforce limits on the
* total amount of time to receive a complete SMTP command line.
*/
non_blocking(vstream_fileno(smtp_client_stream), NON_BLOCKING);
/*
* We use the event_server framework. This means we get already-accepted
* connections so we have to invoke getpeername() to find out the remote
* address and port.
*/
/* Best effort - if this non-blocking write(2) fails, so be it. */
#define PSC_SERVICE_DISCONNECT_AND_RETURN(stream) do { \
(void) write(vstream_fileno(stream), \
"421 4.3.2 No system resources\r\n", \
sizeof("421 4.3.2 No system resources\r\n") - 1); \
event_server_disconnect(stream); \
return; \
} while (0);
/*
* Look up the remote SMTP client address and port.
*/
if (getpeername(vstream_fileno(smtp_client_stream), (struct sockaddr *)
& addr_storage, &addr_storage_len) < 0) {
msg_warn("getpeername: %m -- dropping this connection");
PSC_SERVICE_DISCONNECT_AND_RETURN(smtp_client_stream);
}
/*
* Convert the remote SMTP client address and port to printable form for
* logging and access control.
*/
if ((aierr = sockaddr_to_hostaddr((struct sockaddr *) & addr_storage,
addr_storage_len, &smtp_client_addr,
&smtp_client_port, 0)) != 0) {
msg_warn("cannot convert client address/port to string: %s"
" -- dropping this connection",
MAI_STRERROR(aierr));
PSC_SERVICE_DISCONNECT_AND_RETURN(smtp_client_stream);
}
if (strncasecmp("::ffff:", smtp_client_addr.buf, 7) == 0)
memmove(smtp_client_addr.buf, smtp_client_addr.buf + 7,
sizeof(smtp_client_addr.buf) - 7);
if (msg_verbose > 1)
msg_info("%s: sq=%d cq=%d connect from [%s]:%s",
myname, psc_post_queue_length, psc_check_queue_length,
smtp_client_addr.buf, smtp_client_port.buf);
/*
* Look up the local SMTP server address and port.
*/
if (getsockname(vstream_fileno(smtp_client_stream), (struct sockaddr *)
& addr_storage, &addr_storage_len) < 0) {
msg_warn("getsockname: %m -- dropping this connection");
PSC_SERVICE_DISCONNECT_AND_RETURN(smtp_client_stream);
}
/*
* Convert the local SMTP server address and port to printable form for
* logging and access control.
*/
if ((aierr = sockaddr_to_hostaddr((struct sockaddr *) & addr_storage,
addr_storage_len, &smtp_server_addr,
&smtp_server_port, 0)) != 0) {
msg_warn("cannot convert server address/port to string: %s"
" -- dropping this connection",
MAI_STRERROR(aierr));
PSC_SERVICE_DISCONNECT_AND_RETURN(smtp_client_stream);
}
if (strncasecmp("::ffff:", smtp_server_addr.buf, 7) == 0)
memmove(smtp_server_addr.buf, smtp_server_addr.buf + 7,
sizeof(smtp_server_addr.buf) - 7);
msg_info("CONNECT from [%s]:%s to [%s]:%s",
smtp_client_addr.buf, smtp_client_port.buf,
smtp_server_addr.buf, smtp_server_port.buf);
/*
* Bundle up all the loose session pieces. This zeroes all flags and time
* stamps.
*/
state = psc_new_session_state(smtp_client_stream, smtp_client_addr.buf,
smtp_client_port.buf);
/*
* Reply with 421 when the client has too many open connections.
*/
if (var_psc_cconn_limit > 0
&& state->client_concurrency > var_psc_cconn_limit) {
msg_info("NOQUEUE: reject: CONNECT from [%s]:%s: too many connections",
state->smtp_client_addr, state->smtp_client_port);
PSC_DROP_SESSION_STATE(state,
"421 4.7.0 Error: too many connections\r\n");
return;
}
/*
* Reply with 421 when we can't forward more connections.
*/
if (var_psc_post_queue_limit > 0
&& psc_post_queue_length >= var_psc_post_queue_limit) {
msg_info("NOQUEUE: reject: CONNECT from [%s]:%s: all server ports busy",
state->smtp_client_addr, state->smtp_client_port);
PSC_DROP_SESSION_STATE(state,
"421 4.3.2 All server ports are busy\r\n");
return;
}
/*
* The permanent white/blacklist has highest precedence.
*/
if (psc_acl != 0) {
switch (psc_acl_eval(state, psc_acl, VAR_PSC_ACL)) {
/*
* Permanently blacklisted.
*/
case PSC_ACL_ACT_BLACKLIST:
msg_info("BLACKLISTED [%s]:%s", PSC_CLIENT_ADDR_PORT(state));
PSC_FAIL_SESSION_STATE(state, PSC_STATE_FLAG_BLIST_FAIL);
switch (psc_blist_action) {
case PSC_ACT_DROP:
PSC_DROP_SESSION_STATE(state,
"521 5.3.2 Service currently unavailable\r\n");
return;
case PSC_ACT_ENFORCE:
PSC_ENFORCE_SESSION_STATE(state,
"550 5.3.2 Service currently unavailable\r\n");
break;
case PSC_ACT_IGNORE:
PSC_UNFAIL_SESSION_STATE(state, PSC_STATE_FLAG_BLIST_FAIL);
/*
* Not: PSC_PASS_SESSION_STATE. Repeat this test the next
* time.
*/
break;
default:
msg_panic("%s: unknown blacklist action value %d",
myname, psc_blist_action);
}
break;
/*
* Permanently whitelisted.
*/
case PSC_ACL_ACT_WHITELIST:
msg_info("WHITELISTED [%s]:%s", PSC_CLIENT_ADDR_PORT(state));
psc_conclude(state);
return;
/*
* Other: dunno (don't know) or error.
*/
default:
break;
}
}
/*
* The temporary whitelist (i.e. the postscreen cache) has the lowest
* precedence. This cache contains information about the results of prior
* tests. Whitelist the client when all enabled test results are still
* valid.
*/
if ((state->flags & PSC_STATE_MASK_ANY_FAIL) == 0
&& psc_cache_map != 0
&& (stamp_str = psc_cache_lookup(psc_cache_map, state->smtp_client_addr)) != 0) {
saved_flags = state->flags;
psc_parse_tests(state, stamp_str, event_time());
state->flags |= saved_flags;
if (msg_verbose)
msg_info("%s: cached + recent flags: %s",
myname, psc_print_state_flags(state->flags, myname));
if ((state->flags & PSC_STATE_MASK_ANY_TODO_FAIL) == 0) {
msg_info("PASS OLD [%s]:%s", PSC_CLIENT_ADDR_PORT(state));
psc_conclude(state);
return;
}
} else {
saved_flags = state->flags;
psc_new_tests(state);
state->flags |= saved_flags;
if (msg_verbose)
msg_info("%s: new + recent flags: %s",
myname, psc_print_state_flags(state->flags, myname));
}
/*
* Don't whitelist clients that connect to backup MX addresses. Fail
* "closed" on error.
*/
if (addr_match_list_match(psc_wlist_if, smtp_server_addr.buf) == 0) {
state->flags |= (PSC_STATE_FLAG_WLIST_FAIL | PSC_STATE_FLAG_NOFORWARD);
msg_info("WHITELIST VETO [%s]:%s", PSC_CLIENT_ADDR_PORT(state));
}
/*
* Reply with 421 when we can't analyze more connections. That also means
* no deep protocol tests when the noforward flag is raised.
*/
if (var_psc_pre_queue_limit > 0
&& psc_check_queue_length - psc_post_queue_length
>= var_psc_pre_queue_limit) {
msg_info("reject: connect from [%s]:%s: all screening ports busy",
state->smtp_client_addr, state->smtp_client_port);
PSC_DROP_SESSION_STATE(state,
"421 4.3.2 All screening ports are busy\r\n");
return;
}
/*
* If the client has no up-to-date results for some tests, do those tests
* first. Otherwise, skip the tests and hand off the connection.
*/
if (state->flags & PSC_STATE_MASK_EARLY_TODO)
psc_early_tests(state);
else if (state->flags & (PSC_STATE_MASK_SMTPD_TODO | PSC_STATE_FLAG_NOFORWARD))
psc_smtpd_tests(state);
else
psc_conclude(state);
}
static void psc_endpt_lookup_done(int endpt_status,
VSTREAM *smtp_client_stream,
MAI_HOSTADDR_STR *smtp_client_addr,
MAI_SERVPORT_STR *smtp_client_port,
MAI_HOSTADDR_STR *smtp_server_addr,
MAI_SERVPORT_STR *smtp_server_port)
{
const char *myname = "psc_endpt_lookup_done";
PSC_STATE *state;
const char *stamp_str;
int saved_flags;
/*
* Best effort - if this non-blocking write(2) fails, so be it.
*/
if (endpt_status < 0) {
(void) write(vstream_fileno(smtp_client_stream),
"421 4.3.2 No system resources\r\n",
sizeof("421 4.3.2 No system resources\r\n") - 1);
event_server_disconnect(smtp_client_stream);
return;
}
if (msg_verbose > 1)
msg_info("%s: sq=%d cq=%d connect from [%s]:%s",
myname, psc_post_queue_length, psc_check_queue_length,
smtp_client_addr->buf, smtp_client_port->buf);
msg_info("CONNECT from [%s]:%s to [%s]:%s",
smtp_client_addr->buf, smtp_client_port->buf,
smtp_server_addr->buf, smtp_server_port->buf);
/*
* Bundle up all the loose session pieces. This zeroes all flags and time
* stamps.
*/
state = psc_new_session_state(smtp_client_stream, smtp_client_addr->buf,
smtp_client_port->buf,
smtp_server_addr->buf,
smtp_server_port->buf);
/*
* Reply with 421 when the client has too many open connections.
*/
if (var_psc_cconn_limit > 0
&& state->client_concurrency > var_psc_cconn_limit) {
msg_info("NOQUEUE: reject: CONNECT from [%s]:%s: too many connections",
state->smtp_client_addr, state->smtp_client_port);
PSC_DROP_SESSION_STATE(state,
"421 4.7.0 Error: too many connections\r\n");
return;
}
/*
* Reply with 421 when we can't forward more connections.
*/
if (var_psc_post_queue_limit > 0
&& psc_post_queue_length >= var_psc_post_queue_limit) {
msg_info("NOQUEUE: reject: CONNECT from [%s]:%s: all server ports busy",
state->smtp_client_addr, state->smtp_client_port);
PSC_DROP_SESSION_STATE(state,
"421 4.3.2 All server ports are busy\r\n");
return;
}
/*
* The permanent white/blacklist has highest precedence.
*/
if (psc_acl != 0) {
switch (psc_acl_eval(state, psc_acl, VAR_PSC_ACL)) {
/*
* Permanently blacklisted.
*/
case PSC_ACL_ACT_BLACKLIST:
msg_info("BLACKLISTED [%s]:%s", PSC_CLIENT_ADDR_PORT(state));
PSC_FAIL_SESSION_STATE(state, PSC_STATE_FLAG_BLIST_FAIL);
switch (psc_blist_action) {
case PSC_ACT_DROP:
PSC_DROP_SESSION_STATE(state,
"521 5.3.2 Service currently unavailable\r\n");
return;
case PSC_ACT_ENFORCE:
PSC_ENFORCE_SESSION_STATE(state,
"550 5.3.2 Service currently unavailable\r\n");
break;
case PSC_ACT_IGNORE:
PSC_UNFAIL_SESSION_STATE(state, PSC_STATE_FLAG_BLIST_FAIL);
/*
* Not: PSC_PASS_SESSION_STATE. Repeat this test the next
* time.
*/
break;
default:
msg_panic("%s: unknown blacklist action value %d",
myname, psc_blist_action);
}
break;
/*
* Permanently whitelisted.
*/
case PSC_ACL_ACT_WHITELIST:
msg_info("WHITELISTED [%s]:%s", PSC_CLIENT_ADDR_PORT(state));
psc_conclude(state);
return;
/*
* Other: dunno (don't know) or error.
*/
default:
break;
}
}
/*
* The temporary whitelist (i.e. the postscreen cache) has the lowest
* precedence. This cache contains information about the results of prior
* tests. Whitelist the client when all enabled test results are still
* valid.
*/
if ((state->flags & PSC_STATE_MASK_ANY_FAIL) == 0
&& psc_cache_map != 0
&& (stamp_str = psc_cache_lookup(psc_cache_map, state->smtp_client_addr)) != 0) {
saved_flags = state->flags;
psc_parse_tests(state, stamp_str, event_time());
state->flags |= saved_flags;
if (msg_verbose)
msg_info("%s: cached + recent flags: %s",
myname, psc_print_state_flags(state->flags, myname));
if ((state->flags & PSC_STATE_MASK_ANY_TODO_FAIL) == 0) {
msg_info("PASS OLD [%s]:%s", PSC_CLIENT_ADDR_PORT(state));
psc_conclude(state);
return;
}
} else {
saved_flags = state->flags;
psc_new_tests(state);
state->flags |= saved_flags;
if (msg_verbose)
msg_info("%s: new + recent flags: %s",
myname, psc_print_state_flags(state->flags, myname));
}
/*
* Don't whitelist clients that connect to backup MX addresses. Fail
* "closed" on error.
*/
if (addr_match_list_match(psc_wlist_if, smtp_server_addr->buf) == 0) {
state->flags |= (PSC_STATE_FLAG_WLIST_FAIL | PSC_STATE_FLAG_NOFORWARD);
msg_info("WHITELIST VETO [%s]:%s", PSC_CLIENT_ADDR_PORT(state));
}
/*
* Reply with 421 when we can't analyze more connections. That also means
* no deep protocol tests when the noforward flag is raised.
*/
if (var_psc_pre_queue_limit > 0
&& psc_check_queue_length - psc_post_queue_length
>= var_psc_pre_queue_limit) {
msg_info("reject: connect from [%s]:%s: all screening ports busy",
state->smtp_client_addr, state->smtp_client_port);
PSC_DROP_SESSION_STATE(state,
"421 4.3.2 All screening ports are busy\r\n");
return;
}
/*
* If the client has no up-to-date results for some tests, do those tests
* first. Otherwise, skip the tests and hand off the connection.
*/
if (state->flags & PSC_STATE_MASK_EARLY_TODO)
psc_early_tests(state);
else if (state->flags & (PSC_STATE_MASK_SMTPD_TODO | PSC_STATE_FLAG_NOFORWARD))
psc_smtpd_tests(state);
else
psc_conclude(state);
}