Adding upstream version 3.4.23.upstream/3.4.23upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 269 insertions, 0 deletions

diff --git a/src/smtp/smtp_reuse.c b/src/smtp/smtp_reuse.c
new file mode 100644
index 0000000..f93ba29
--- /dev/null
+++ b/src/smtp/smtp_reuse.c
@@ -0,0 +1,269 @@
+/*++
+/* NAME
+/*	smtp_reuse 3
+/* SUMMARY
+/*	SMTP session cache glue
+/* SYNOPSIS
+/*	#include <smtp.h>
+/*	#include <smtp_reuse.h>
+/*
+/*	void	smtp_save_session(state, name_key_flags, endp_key_flags)
+/*	SMTP_STATE *state;
+/*	int	name_key_flags;
+/*	int	endp_key_flags;
+/*
+/*	SMTP_SESSION *smtp_reuse_nexthop(state, name_key_flags)
+/*	SMTP_STATE *state;
+/*	int	name_key_flags;
+/*
+/*	SMTP_SESSION *smtp_reuse_addr(state, endp_key_flags)
+/*	SMTP_STATE *state;
+/*	int	endp_key_flags;
+/* DESCRIPTION
+/*	This module implements the SMTP client specific interface to
+/*	the generic session cache infrastructure.
+/*
+/*	The caller needs to include additional state in _key_flags
+/*	to avoid false sharing of SASL-authenticated or TLS-authenticated
+/*	sessions.
+/*
+/*	smtp_save_session() stores the current session under the
+/*	delivery request next-hop logical destination (if applicable)
+/*	and under the remote server address. The SMTP_SESSION object
+/*	is destroyed.
+/*
+/*	smtp_reuse_nexthop() looks up a cached session by its
+/*	delivery request next-hop destination, and verifies that
+/*	the session is still alive. The restored session information
+/*	includes the "best MX" bit and overrides the iterator dest,
+/*	host and addr fields. The result is null in case of failure.
+/*
+/*	smtp_reuse_addr() looks up a cached session by its server
+/*	address, and verifies that the session is still alive.
+/*	The restored session information does not include the "best
+/*	MX" bit, and does not override the iterator dest, host and
+/*	addr fields. The result is null in case of failure.
+/*
+/*	Arguments:
+/* .IP state
+/*	SMTP client state, including the current session, the original
+/*	next-hop domain, etc.
+/* .IP name_key_flags
+/*	Explicit declaration of context that should be used to look
+/*	up a cached connection by its logical destination.
+/*	See smtp_key(3) for details.
+/* .IP endp_key_flags
+/*	Explicit declaration of context that should be used to look
+/*	up a cached connection by its server address.
+/*	See smtp_key(3) for details.
+/* LICENSE
+/* .ad
+/* .fi
+/*	The Secure Mailer license must be distributed with this software.
+/* AUTHOR(S)
+/*	Wietse Venema
+/*	IBM T.J. Watson Research
+/*	P.O. Box 704
+/*	Yorktown Heights, NY 10598, USA
+/*
+/*	Wietse Venema
+/*	Google, Inc.
+/*	111 8th Avenue
+/*	New York, NY 10011, USA
+/*--*/
+
+/* System library. */
+
+#include <sys_defs.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <unistd.h>
+#include <string.h>
+
+/* Utility library. */
+
+#include <msg.h>
+#include <mymalloc.h>
+#include <vstream.h>
+#include <vstring.h>
+#include <htable.h>
+#include <stringops.h>
+
+/* Global library. */
+
+#include <scache.h>
+#include <mail_params.h>
+
+/* Application-specific. */
+
+#include <smtp.h>
+#include <smtp_reuse.h>
+
+ /*
+  * Key field delimiter, and place holder field value for
+  * unavailable/inapplicable information.
+  */
+#define SMTP_REUSE_KEY_DELIM_NA	"\n*"
+
+/* smtp_save_session - save session under next-hop name and server address */
+
+void    smtp_save_session(SMTP_STATE *state, int name_key_flags,
+			          int endp_key_flags)
+{
+    SMTP_SESSION *session = state->session;
+    int     fd;
+
+    /*
+     * Encode the delivery request next-hop destination, if applicable. Reuse
+     * storage that is also used for cache lookup queries.
+     * 
+     * HAVE_SCACHE_REQUEST_NEXTHOP() controls whether or not to reuse or cache a
+     * connection by its delivery request next-hop destination. The idea is
+     * 1) to allow a reuse request to skip over bad hosts, and 2) to avoid
+     * caching a less-preferred connection when a more-preferred connection
+     * was possible.
+     */
+    if (HAVE_SCACHE_REQUEST_NEXTHOP(state))
+	smtp_key_prefix(state->dest_label, SMTP_REUSE_KEY_DELIM_NA,
+			state->iterator, name_key_flags);
+
+    /*
+     * Encode the physical endpoint name. Reuse storage that is also used for
+     * cache lookup queries.
+     */
+    smtp_key_prefix(state->endp_label, SMTP_REUSE_KEY_DELIM_NA,
+		    state->iterator, endp_key_flags);
+
+    /*
+     * Passivate the SMTP_SESSION object, destroying the object in the
+     * process. Reuse storage that is also used for cache lookup results.
+     */
+    fd = smtp_session_passivate(session, state->dest_prop, state->endp_prop);
+    state->session = 0;
+
+    /*
+     * Save the session under the delivery request next-hop name, if
+     * applicable.
+     * 
+     * XXX The logical to physical binding can be kept for as long as the DNS
+     * allows us to (but that could result in the caching of lots of unused
+     * bindings). The session should be idle for no more than 30 seconds or
+     * so.
+     */
+    if (HAVE_SCACHE_REQUEST_NEXTHOP(state))
+	scache_save_dest(smtp_scache, var_smtp_cache_conn,
+			 STR(state->dest_label), STR(state->dest_prop),
+			 STR(state->endp_label));
+
+    /*
+     * Save every good session under its physical endpoint address.
+     */
+    scache_save_endp(smtp_scache, var_smtp_cache_conn, STR(state->endp_label),
+		     STR(state->endp_prop), fd);
+}
+
+/* smtp_reuse_common - common session reuse code */
+
+static SMTP_SESSION *smtp_reuse_common(SMTP_STATE *state, int fd,
+				               const char *label)
+{
+    const char *myname = "smtp_reuse_common";
+    SMTP_ITERATOR *iter = state->iterator;
+    SMTP_SESSION *session;
+
+    /*
+     * Re-activate the SMTP_SESSION object.
+     */
+    session = smtp_session_activate(fd, state->iterator, state->dest_prop,
+				    state->endp_prop);
+    if (session == 0) {
+	msg_warn("%s: bad cached session attribute for %s", myname, label);
+	(void) close(fd);
+	return (0);
+    }
+    state->session = session;
+    session->state = state;
+
+    /*
+     * Send an RSET probe to verify that the session is still good.
+     */
+    if (smtp_rset(state) < 0
+	|| (session->features & SMTP_FEATURE_RSET_REJECTED) != 0) {
+	smtp_session_free(session);
+	return (state->session = 0);
+    }
+
+    /*
+     * Avoid poor performance when TCP MSS > VSTREAM_BUFSIZE.
+     */
+    vstream_tweak_sock(session->stream);
+
+    /*
+     * Update the list of used cached addresses.
+     */
+    htable_enter(state->cache_used, STR(iter->addr), (void *) 0);
+
+    return (session);
+}
+
+/* smtp_reuse_nexthop - reuse session cached under nexthop name */
+
+SMTP_SESSION *smtp_reuse_nexthop(SMTP_STATE *state, int name_key_flags)
+{
+    SMTP_SESSION *session;
+    int     fd;
+
+    /*
+     * Look up the session by its logical name.
+     */
+    smtp_key_prefix(state->dest_label, SMTP_REUSE_KEY_DELIM_NA,
+		    state->iterator, name_key_flags);
+    if ((fd = scache_find_dest(smtp_scache, STR(state->dest_label),
+			       state->dest_prop, state->endp_prop)) < 0)
+	return (0);
+
+    /*
+     * Re-activate the SMTP_SESSION object, and verify that the session is
+     * still good.
+     */
+    session = smtp_reuse_common(state, fd, STR(state->dest_label));
+    return (session);
+}
+
+/* smtp_reuse_addr - reuse session cached under numerical address */
+
+SMTP_SESSION *smtp_reuse_addr(SMTP_STATE *state, int endp_key_flags)
+{
+    SMTP_SESSION *session;
+    int     fd;
+
+    /*
+     * Address-based reuse is safe for security levels that require TLS
+     * certificate checks, as long as the current nexhop is included in the
+     * cache lookup key (COND_TLS_SMTP_KEY_FLAG_CUR_NEXTHOP). This is
+     * sufficient to prevent the reuse of a TLS-authenticated connection to
+     * the same MX hostname, IP address, and port, but for a different
+     * current nexthop destination with a different TLS policy.
+     */
+
+    /*
+     * Look up the session by its IP address. This means that we have no
+     * destination-to-address binding properties.
+     */
+    smtp_key_prefix(state->endp_label, SMTP_REUSE_KEY_DELIM_NA,
+		    state->iterator, endp_key_flags);
+    if ((fd = scache_find_endp(smtp_scache, STR(state->endp_label),
+			       state->endp_prop)) < 0)
+	return (0);
+    VSTRING_RESET(state->dest_prop);
+    VSTRING_TERMINATE(state->dest_prop);
+
+    /*
+     * Re-activate the SMTP_SESSION object, and verify that the session is
+     * still good.
+     */
+    session = smtp_reuse_common(state, fd, STR(state->endp_label));
+
+    return (session);
+}