static int smtp_reuse_session(SMTP_STATE *state, int lookup_mx,
const char *domain, unsigned port,
DNS_RR **addr_list, int domain_best_pref)
{
int session_count = 0;
DNS_RR *addr;
DNS_RR *next;
MAI_HOSTADDR_STR hostaddr;
SMTP_SESSION *session;
/*
* First, search the cache by logical destination. We truncate the server
* address list when all the sessions for this destination are used up,
* to reduce the number of variables that need to be checked later.
*
* Note: lookup by logical destination restores the "best MX" bit.
*/
if (*addr_list && SMTP_RCPT_LEFT(state) > 0
&& (session = smtp_reuse_domain(state, lookup_mx, domain, port)) != 0) {
session_count = 1;
smtp_update_addr_list(addr_list, session->addr, session_count);
if ((state->misc_flags & SMTP_MISC_FLAG_FINAL_NEXTHOP)
&& *addr_list == 0)
state->misc_flags |= SMTP_MISC_FLAG_FINAL_SERVER;
smtp_xfer(state);
smtp_cleanup_session(state);
}
/*
* Second, search the cache by primary MX address. Again, we use address
* list truncation so that we have to check fewer variables later.
*
* XXX This loop is safe because smtp_update_addr_list() either truncates
* the list to zero length, or removes at most one list element.
*/
for (addr = *addr_list; SMTP_RCPT_LEFT(state) > 0 && addr; addr = next) {
if (addr->pref != domain_best_pref)
break;
next = addr->next;
if (dns_rr_to_pa(addr, &hostaddr) != 0
&& (session = smtp_reuse_addr(state, hostaddr.buf, port)) != 0) {
session->features |= SMTP_FEATURE_BEST_MX;
session_count += 1;
smtp_update_addr_list(addr_list, session->addr, session_count);
if (*addr_list == 0)
next = 0;
if ((state->misc_flags & SMTP_MISC_FLAG_FINAL_NEXTHOP)
&& next == 0)
state->misc_flags |= SMTP_MISC_FLAG_FINAL_SERVER;
smtp_xfer(state);
smtp_cleanup_session(state);
}
}
return (session_count);
}
static int smtp_reuse_session(SMTP_STATE *state, DNS_RR **addr_list,
int domain_best_pref)
{
int session_count = 0;
DNS_RR *addr;
DNS_RR *next;
MAI_HOSTADDR_STR hostaddr;
SMTP_SESSION *session;
SMTP_ITERATOR *iter = state->iterator;
DSN_BUF *why = state->why;
/*
* First, search the cache by request nexthop. We truncate the server
* address list when all the sessions for this destination are used up,
* to reduce the number of variables that need to be checked later.
*
* Note: lookup by logical destination restores the "best MX" bit.
*
* smtp_reuse_nexthop() clobbers the iterators's "dest" attribute. We save
* and restore it here, so that subsequent connections will use the
* proper nexthop information.
*
* We request a dummy "TLS disabled" policy for connection-cache lookup by
* request nexthop only. If we find a saved connection, then we know that
* plaintext was permitted, because we never save a connection after
* turning on TLS.
*/
#ifdef USE_TLS
smtp_tls_policy_dummy(state->tls);
#endif
SMTP_ITER_SAVE_DEST(state->iterator);
if (*addr_list && SMTP_RCPT_LEFT(state) > 0
&& HAVE_NEXTHOP_STATE(state)
&& (session = smtp_reuse_nexthop(state, SMTP_KEY_MASK_SCACHE_DEST_LABEL)) != 0) {
session_count = 1;
smtp_update_addr_list(addr_list, STR(iter->addr), session_count);
if ((state->misc_flags & SMTP_MISC_FLAG_FINAL_NEXTHOP)
&& *addr_list == 0)
state->misc_flags |= SMTP_MISC_FLAG_FINAL_SERVER;
smtp_xfer(state);
smtp_cleanup_session(state);
}
SMTP_ITER_RESTORE_DEST(state->iterator);
/*
* Second, search the cache by primary MX address. Again, we use address
* list truncation so that we have to check fewer variables later.
*
* XXX This loop is safe because smtp_update_addr_list() either truncates
* the list to zero length, or removes at most one list element.
*
* Currently, we use smtp_reuse_addr() only for SASL-unauthenticated
* connections. Furthermore, we rely on smtp_reuse_addr() to look up an
* existing SASL-unauthenticated connection only when a new connection
* would be guaranteed not to require SASL authentication.
*
* In addition, we rely on smtp_reuse_addr() to look up an existing
* plaintext connection only when a new connection would be guaranteed
* not to use TLS.
*
* For more precise control over reuse, the iterator should look up SASL and
* TLS policy as it evaluates mail exchangers in order, instead of
* relying on duplicate lookup request code in smtp_reuse(3) and
* smtp_session(3).
*/
for (addr = *addr_list; SMTP_RCPT_LEFT(state) > 0 && addr; addr = next) {
if (addr->pref != domain_best_pref)
break;
next = addr->next;
if (dns_rr_to_pa(addr, &hostaddr) == 0) {
msg_warn("cannot convert type %s record to printable address",
dns_strtype(addr->type));
/* XXX Assume there is no code at the end of this loop. */
continue;
}
vstring_strcpy(iter->addr, hostaddr.buf);
vstring_strcpy(iter->host, SMTP_HNAME(addr));
iter->rr = addr;
#ifdef USE_TLS
if (!smtp_tls_policy_cache_query(why, state->tls, iter)) {
msg_warn("TLS policy lookup error for %s/%s: %s",
STR(iter->dest), STR(iter->host), STR(why->reason));
continue;
/* XXX Assume there is no code at the end of this loop. */
}
#endif
if ((session = smtp_reuse_addr(state,
SMTP_KEY_MASK_SCACHE_ENDP_LABEL)) != 0) {
session->features |= SMTP_FEATURE_BEST_MX;
session_count += 1;
smtp_update_addr_list(addr_list, STR(iter->addr), session_count);
if (*addr_list == 0)
next = 0;
if ((state->misc_flags & SMTP_MISC_FLAG_FINAL_NEXTHOP)
&& next == 0)
state->misc_flags |= SMTP_MISC_FLAG_FINAL_SERVER;
smtp_xfer(state);
smtp_cleanup_session(state);
}
}
return (session_count);
}
