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/* #include <smtp_reuse.h>
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/* void smtp_save_session(state)
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/* SMTP_SESSION *smtp_reuse_domain(state, lookup_mx, domain, port)
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/* SMTP_SESSION *smtp_reuse_addr(state, addr, port)
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/* void smtp_save_session(state, name_key_flags, endp_key_flags)
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/* int name_key_flags;
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/* int endp_key_flags;
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/* SMTP_SESSION *smtp_reuse_nexthop(state, name_key_flags)
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/* int name_key_flags;
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/* SMTP_SESSION *smtp_reuse_addr(state, endp_key_flags)
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/* int endp_key_flags;
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/* This module implements the SMTP client specific interface to
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/* the generic session cache infrastructure.
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/* Each cached connection identifier includes the name of the
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/* mail delivery service. Thus, cached connections are not
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/* shared between different services.
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/* A cached connection is closed when the TLS policy requires
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/* that TLS is enabled.
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/* smtp_save_session() stores the current session under the
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/* next-hop logical destination (if available) and under the
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/* remote server address. The SMTP_SESSION object is destroyed.
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/* smtp_reuse_domain() looks up a cached session by its logical
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/* smtp_reuse_nexthop() looks up a cached session by its logical
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/* destination, and verifies that the session is still alive.
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/* The restored session information includes the "best MX" bit.
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/* The restored session information includes the "best MX" bit
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/* and overrides the iterator dest, host and addr fields.
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/* The result is null in case of failure.
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/* smtp_reuse_addr() looks up a cached session by its server
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/* address, and verifies that the session is still alive.
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/* This operation is disabled when the legacy tls_per_site
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/* or smtp_sasl_password_maps features are enabled.
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/* The restored session information does not include the "best
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/* MX" bit, and does not override the iterator dest, host and
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/* The result is null in case of failure.
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/* SMTP client state, including the current session, the original
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/* next-hop domain, etc.
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/* Whether or not the domain is subject to MX lookup.
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/* Domain name or bare numerical address.
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/* The remote server address as printable text.
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/* The remote server port, network byte order.
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/* Explicit declaration of context that should be used to look
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/* up a cached connection by its logical destination.
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/* See smtp_key(3) for details.
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/* Explicit declaration of context that should be used to look
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/* up a cached connection by its server address.
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/* See smtp_key(3) for details.
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#include <smtp_reuse.h>
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* We encode the MX lookup/A lookup method into the name under which SMTP
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* session information is cached. The following macros serve to make the
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* remainder of the code less obscure.
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* Key field delimiter, and place holder field value for
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* unavailable/inapplicable information.
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#define NO_MX_LOOKUP 0
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#define SMTP_SCACHE_LABEL(mx_lookup_flag) \
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((mx_lookup_flag) ? "%s:%s:%u" : "%s:[%s]:%u")
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#define SMTP_REUSE_KEY_DELIM_NA "\n*"
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/* smtp_save_session - save session under next-hop name and server address */
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void smtp_save_session(SMTP_STATE *state)
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void smtp_save_session(SMTP_STATE *state, int name_key_flags,
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SMTP_SESSION *session = state->session;
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* Encode the next-hop logical destination, if available. Reuse storage
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* that is also used for cache lookup queries.
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* Note: if the label needs to be made more specific (with e.g., SASL login
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* information), just append the text with vstring_sprintf_append().
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if (HAVE_NEXTHOP_STATE(state))
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vstring_sprintf(state->dest_label,
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SMTP_SCACHE_LABEL(state->nexthop_lookup_mx),
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state->service, state->nexthop_domain,
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ntohs(state->nexthop_port));
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smtp_key_prefix(state->dest_label, SMTP_REUSE_KEY_DELIM_NA,
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state->iterator, name_key_flags);
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* Encode the physical endpoint name. Reuse storage that is also used for
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* cache lookup queries.
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* Note: if the label needs to be made more specific (with e.g., SASL login
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* information), just append the text with vstring_sprintf_append().
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vstring_sprintf(state->endp_label,
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SMTP_SCACHE_LABEL(NO_MX_LOOKUP),
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state->service, session->addr, ntohs(session->port));
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smtp_key_prefix(state->endp_label, SMTP_REUSE_KEY_DELIM_NA,
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state->iterator, endp_key_flags);
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* Passivate the SMTP_SESSION object, destroying the object in the
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const char *label)
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const char *myname = "smtp_reuse_common";
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SMTP_ITERATOR *iter = state->iterator;
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SMTP_SESSION *session;
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* Can't happen. Both smtp_reuse_nexthop() and smtp_reuse_addr() decline
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* the request when the TLS policy is not TLS_LEV_NONE.
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if (state->tls->level > TLS_LEV_NONE)
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msg_panic("%s: unexpected plain-text cached session to %s",
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* Re-activate the SMTP_SESSION object.
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session = smtp_session_activate(fd, state->dest_prop, state->endp_prop);
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session = smtp_session_activate(fd, state->iterator, state->dest_prop,
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if (session == 0) {
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msg_warn("%s: bad cached session attribute for %s", myname, label);
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(void) close(fd);
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state->session = session;
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session->state = state;
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* Cached connections are always plaintext. They must never be reused when
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* TLS encryption is required.
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* As long as we support the legacy smtp_tls_per_site feature, we must
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* search the connection cache before making TLS policy decisions. This
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* is because the policy can depend on the server name. For example, a
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* site could have a global policy that requires encryption, with
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* per-server exceptions that allow plaintext.
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* With the newer smtp_tls_policy_maps feature, the policy depends on the
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* next-hop destination only. We can avoid unnecessary connection cache
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* lookups, because we can compute the TLS policy much earlier.
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if (session->tls_level >= TLS_LEV_ENCRYPT) {
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msg_info("%s: skipping plain-text cached session to %s",
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smtp_quit(state); /* Close politely */
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smtp_session_free(session); /* And avoid leaks */
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return (state->session = 0);
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session->tls = state->tls; /* TEMPORARY */
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* Update the list of used cached addresses.
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htable_enter(state->cache_used, session->addr, (char *) 0);
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htable_enter(state->cache_used, STR(iter->addr), (char *) 0);
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return (session);
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/* smtp_reuse_domain - reuse session cached under domain name */
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/* smtp_reuse_nexthop - reuse session cached under nexthop name */
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SMTP_SESSION *smtp_reuse_domain(SMTP_STATE *state, int lookup_mx,
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const char *domain, unsigned port)
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SMTP_SESSION *smtp_reuse_nexthop(SMTP_STATE *state, int name_key_flags)
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SMTP_SESSION *session;
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* Don't look up an existing plaintext connection when a new connection
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* would (try to) use TLS.
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if (state->tls->level > TLS_LEV_NONE)
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* Look up the session by its logical name.
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* Note: if the label needs to be made more specific (with e.g., SASL login
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* information), just append the text with vstring_sprintf_append().
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vstring_sprintf(state->dest_label, SMTP_SCACHE_LABEL(lookup_mx),
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state->service, domain, ntohs(port));
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smtp_key_prefix(state->dest_label, SMTP_REUSE_KEY_DELIM_NA,
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state->iterator, name_key_flags);
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if ((fd = scache_find_dest(smtp_scache, STR(state->dest_label),
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state->dest_prop, state->endp_prop)) < 0)
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/* smtp_reuse_addr - reuse session cached under numerical address */
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SMTP_SESSION *smtp_reuse_addr(SMTP_STATE *state, const char *addr,
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SMTP_SESSION *smtp_reuse_addr(SMTP_STATE *state, int endp_key_flags)
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SMTP_SESSION *session;
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* XXX Disable connection cache lookup by server IP address when the
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* tls_per_site policy or smtp_sasl_password_maps features are enabled.
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* This connection may have been created under a different hostname that
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* resolves to the same IP address. We don't want to use the wrong SASL
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* credentials or the wrong TLS policy.
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* Don't look up an existing plaintext connection when a new connection
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* would (try to) use TLS.
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if ((var_smtp_tls_per_site && *var_smtp_tls_per_site)
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|| (var_smtp_tls_policy && *var_smtp_tls_policy))
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if (state->tls->level > TLS_LEV_NONE)
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* Look up the session by its IP address. This means that we have no
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* destination-to-address binding properties.
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* Note: if the label needs to be made more specific (with e.g., SASL login
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* information), just append the text with vstring_sprintf_append().
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vstring_sprintf(state->endp_label, SMTP_SCACHE_LABEL(NO_MX_LOOKUP),
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state->service, addr, ntohs(port));
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smtp_key_prefix(state->endp_label, SMTP_REUSE_KEY_DELIM_NA,
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state->iterator, endp_key_flags);
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if ((fd = scache_find_endp(smtp_scache, STR(state->endp_label),
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state->endp_prop)) < 0)
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session = smtp_reuse_common(state, fd, STR(state->endp_label));
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* XXX What if hostnames don't match (addr->name versus session->name),
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* or if the SASL login name for this host does not match the SASL login
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* name that was used when opening this session? If something depends
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* critically on such information being identical, then that information
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* should be included in the logical and physical labels under which a
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return (session);
added
removed
src/smtp/smtp_reuse.c
