1 files changed, 446 insertions, 0 deletions

diff --git a/src/smtp/smtp_session.c b/src/smtp/smtp_session.c
new file mode 100644
index 0000000..1b3a20e
--- /dev/null
+++ b/src/smtp/smtp_session.c
@@ -0,0 +1,446 @@
+/*++
+/* NAME
+/*	smtp_session 3
+/* SUMMARY
+/*	SMTP_SESSION structure management
+/* SYNOPSIS
+/*	#include "smtp.h"
+/*
+/*	SMTP_SESSION *smtp_session_alloc(stream, iter, start, flags)
+/*	VSTREAM	*stream;
+/*	SMTP_ITERATOR *iter;
+/*	time_t	start;
+/*	int	flags;
+/*
+/*	void	smtp_session_free(session)
+/*	SMTP_SESSION *session;
+/*
+/*	int	smtp_session_passivate(session, dest_prop, endp_prop)
+/*	SMTP_SESSION *session;
+/*	VSTRING	*dest_prop;
+/*	VSTRING	*endp_prop;
+/*
+/*	SMTP_SESSION *smtp_session_activate(fd, iter, dest_prop, endp_prop)
+/*	int	fd;
+/*	SMTP_ITERATOR *iter;
+/*	VSTRING	*dest_prop;
+/*	VSTRING	*endp_prop;
+/* DESCRIPTION
+/*	smtp_session_alloc() allocates memory for an SMTP_SESSION structure
+/*	and initializes it with the given stream and destination, host name
+/*	and address information.  The host name and address strings are
+/*	copied. The port is in network byte order.
+/*
+/*	smtp_session_free() destroys an SMTP_SESSION structure and its
+/*	members, making memory available for reuse. It will handle the
+/*	case of a null stream and will assume it was given a different
+/*	purpose.
+/*
+/*	smtp_session_passivate() flattens an SMTP session (including
+/*	TLS context) so that it can be cached. The SMTP_SESSION
+/*	structure is destroyed.
+/*
+/*	smtp_session_activate() inflates a flattened SMTP session
+/*	so that it can be used. The input property arguments are
+/*	modified.
+/*
+/*	Arguments:
+/* .IP stream
+/*	A full-duplex stream.
+/* .IP iter
+/*	The literal next-hop or fall-back destination including
+/*	the optional [] and including the :port or :service;
+/*	the name of the remote host;
+/*	the printable address of the remote host;
+/*	the remote port in network byte order.
+/* .IP start
+/*	The time when this connection was opened.
+/* .IP flags
+/*	Zero or more of the following:
+/* .RS
+/* .IP SMTP_MISC_FLAG_CONN_LOAD
+/*	Enable re-use of cached SMTP or LMTP connections.
+/* .IP SMTP_MISC_FLAG_CONN_STORE
+/*	Enable saving of cached SMTP or LMTP connections.
+/* .RE
+/*	SMTP_MISC_FLAG_CONN_MASK corresponds with both _LOAD and _STORE.
+/* .IP dest_prop
+/*	Destination specific session properties: the server is the
+/*	best MX host for the current logical destination, the dest,
+/*	host, and addr properties. When dest_prop is non-empty, it
+/*	overrides the iterator dest, host, and addr properties.  It
+/*	is the caller's responsibility to save the current nexthop
+/*	with SMTP_ITER_SAVE_DEST() and to restore it afterwards
+/*	with SMTP_ITER_RESTORE_DEST() before trying alternatives.
+/* .IP endp_prop
+/*	Endpoint specific session properties: all the features
+/*	advertised by the remote server.
+/* 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
+/*
+/*	Viktor Dukhovni
+/*--*/
+
+/* System library. */
+
+#include <sys_defs.h>
+#include <stdlib.h>
+#include <string.h>
+#include <netinet/in.h>
+
+/* Utility library. */
+
+#include <msg.h>
+#include <mymalloc.h>
+#include <vstring.h>
+#include <vstream.h>
+#include <stringops.h>
+
+/* Global library. */
+
+#include <mime_state.h>
+#include <debug_peer.h>
+#include <mail_params.h>
+
+/* TLS Library. */
+
+#include <tls_proxy.h>
+
+/* Application-specific. */
+
+#include "smtp.h"
+#include "smtp_sasl.h"
+
+ /*
+  * Local, because these are meaningful only for code in this file.
+  */
+#define SESS_ATTR_DEST		"destination"
+#define SESS_ATTR_HOST		"host_name"
+#define SESS_ATTR_ADDR		"host_addr"
+#define SESS_ATTR_DEST_FEATURES	"destination_features"
+
+#define SESS_ATTR_TLS_LEVEL	"tls_level"
+#define SESS_ATTR_REUSE_COUNT	"reuse_count"
+#define SESS_ATTR_ENDP_FEATURES	"endpoint_features"
+#define SESS_ATTR_EXPIRE_TIME	"expire_time"
+
+/* smtp_session_alloc - allocate and initialize SMTP_SESSION structure */
+
+SMTP_SESSION *smtp_session_alloc(VSTREAM *stream, SMTP_ITERATOR *iter,
+				         time_t start, int flags)
+{
+    SMTP_SESSION *session;
+    const char *host = STR(iter->host);
+    const char *addr = STR(iter->addr);
+    unsigned port = iter->port;
+
+    session = (SMTP_SESSION *) mymalloc(sizeof(*session));
+    session->stream = stream;
+    session->iterator = iter;
+    session->namaddr = concatenate(host, "[", addr, "]", (char *) 0);
+    session->helo = 0;
+    session->port = port;
+    session->features = 0;
+
+    session->size_limit = 0;
+    session->error_mask = 0;
+    session->buffer = vstring_alloc(100);
+    session->scratch = vstring_alloc(100);
+    session->scratch2 = vstring_alloc(100);
+    smtp_chat_init(session);
+    session->mime_state = 0;
+
+    if (session->port) {
+	vstring_sprintf(session->buffer, "%s:%d",
+			session->namaddr, ntohs(session->port));
+	session->namaddrport = mystrdup(STR(session->buffer));
+    } else
+	session->namaddrport = mystrdup(session->namaddr);
+
+    session->send_proto_helo = 0;
+
+    if (flags & SMTP_MISC_FLAG_CONN_STORE)
+	CACHE_THIS_SESSION_UNTIL(start + var_smtp_reuse_time);
+    else
+	DONT_CACHE_THIS_SESSION;
+    session->reuse_count = 0;
+    USE_NEWBORN_SESSION;			/* He's not dead Jim! */
+
+#ifdef USE_SASL_AUTH
+    smtp_sasl_connect(session);
+#endif
+
+#ifdef USE_TLS
+    session->tls_context = 0;
+    session->tls_retry_plain = 0;
+    session->tls_nexthop = 0;
+#endif
+    session->state = 0;
+    debug_peer_check(host, addr);
+    return (session);
+}
+
+/* smtp_session_free - destroy SMTP_SESSION structure and contents */
+
+void    smtp_session_free(SMTP_SESSION *session)
+{
+#ifdef USE_TLS
+    if (session->stream) {
+	vstream_fflush(session->stream);
+    }
+    if (session->tls_context) {
+	if (session->features &
+	    (SMTP_FEATURE_FROM_CACHE | SMTP_FEATURE_FROM_PROXY))
+	    tls_proxy_context_free(session->tls_context);
+	else
+	    tls_client_stop(smtp_tls_ctx, session->stream,
+			  var_smtp_starttls_tmout, 0, session->tls_context);
+    }
+#endif
+    if (session->stream)
+	vstream_fclose(session->stream);
+    myfree(session->namaddr);
+    myfree(session->namaddrport);
+    if (session->helo)
+	myfree(session->helo);
+
+    vstring_free(session->buffer);
+    vstring_free(session->scratch);
+    vstring_free(session->scratch2);
+
+    if (session->history)
+	smtp_chat_reset(session);
+    if (session->mime_state)
+	mime_state_free(session->mime_state);
+
+#ifdef USE_SASL_AUTH
+    smtp_sasl_cleanup(session);
+#endif
+
+    debug_peer_restore();
+    myfree((void *) session);
+}
+
+/* smtp_session_passivate - passivate an SMTP_SESSION object */
+
+int     smtp_session_passivate(SMTP_SESSION *session, VSTRING *dest_prop,
+			               VSTRING *endp_prop)
+{
+    SMTP_ITERATOR *iter = session->iterator;
+    VSTREAM *mp;
+    int     fd;
+
+    /*
+     * Encode the delivery request next-hop to endpoint binding properties:
+     * whether or not this server is best MX host for the delivery request
+     * next-hop or fall-back logical destination (this information is needed
+     * for loop handling in smtp_proto()).
+     * 
+     * TODO: save SASL username and password information so that we can
+     * correctly save a reused authenticated connection.
+     * 
+     * These memory writes should never fail.
+     */
+    if ((mp = vstream_memopen(dest_prop, O_WRONLY)) == 0
+	|| attr_print_plain(mp, ATTR_FLAG_NONE,
+			    SEND_ATTR_STR(SESS_ATTR_DEST, STR(iter->dest)),
+			    SEND_ATTR_STR(SESS_ATTR_HOST, STR(iter->host)),
+			    SEND_ATTR_STR(SESS_ATTR_ADDR, STR(iter->addr)),
+			    SEND_ATTR_INT(SESS_ATTR_DEST_FEATURES,
+			 session->features & SMTP_FEATURE_DESTINATION_MASK),
+			    ATTR_TYPE_END) != 0
+	|| vstream_fclose(mp) != 0)
+	msg_fatal("smtp_session_passivate: can't save dest properties: %m");
+
+    /*
+     * Encode the physical endpoint properties: all the session properties
+     * except for "session from cache", "best MX", or "RSET failure". Plus
+     * the TLS level, reuse count, and connection expiration time.
+     * 
+     * XXX Should also record how many non-delivering mail transactions there
+     * were during this session, and perhaps other statistics, so that we
+     * don't reuse a session too much.
+     * 
+     * TODO: passivate SASL username and password information so that we can
+     * correctly save a reused authenticated connection.
+     * 
+     * These memory writes should never fail.
+     */
+    if ((mp = vstream_memopen(endp_prop, O_WRONLY)) == 0
+	|| attr_print_plain(mp, ATTR_FLAG_NONE,
+#ifdef USE_TLS
+			    SEND_ATTR_INT(SESS_ATTR_TLS_LEVEL,
+					  session->state->tls->level),
+#endif
+			    SEND_ATTR_INT(SESS_ATTR_REUSE_COUNT,
+					  session->reuse_count),
+			    SEND_ATTR_INT(SESS_ATTR_ENDP_FEATURES,
+			    session->features & SMTP_FEATURE_ENDPOINT_MASK),
+			    SEND_ATTR_LONG(SESS_ATTR_EXPIRE_TIME,
+					   (long) session->expire_time),
+			    ATTR_TYPE_END) != 0
+
+    /*
+     * Append the passivated TLS context. These memory writes should never
+     * fail.
+     */
+#ifdef USE_TLS
+	|| (session->tls_context
+	    && attr_print_plain(mp, ATTR_FLAG_NONE,
+				SEND_ATTR_FUNC(tls_proxy_context_print,
+					     (void *) session->tls_context),
+				ATTR_TYPE_END) != 0)
+#endif
+	|| vstream_fclose(mp) != 0)
+	msg_fatal("smtp_session_passivate: cannot save TLS context: %m");
+
+    /*
+     * Salvage the underlying file descriptor, and destroy the session
+     * object.
+     */
+    fd = vstream_fileno(session->stream);
+    vstream_fdclose(session->stream);
+    session->stream = 0;
+    smtp_session_free(session);
+
+    return (fd);
+}
+
+/* smtp_session_activate - re-activate a passivated SMTP_SESSION object */
+
+SMTP_SESSION *smtp_session_activate(int fd, SMTP_ITERATOR *iter,
+				            VSTRING *dest_prop,
+				            VSTRING *endp_prop)
+{
+    const char *myname = "smtp_session_activate";
+    VSTREAM *mp;
+    SMTP_SESSION *session;
+    int     endp_features;		/* server features */
+    int     dest_features;		/* server features */
+    long    expire_time;		/* session re-use expiration time */
+    int     reuse_count;		/* # times reused */
+
+#ifdef USE_TLS
+    TLS_SESS_STATE *tls_context = 0;
+    SMTP_TLS_POLICY *tls = iter->parent->tls;
+
+#define TLS_PROXY_CONTEXT_FREE() do { \
+    if (tls_context) \
+	tls_proxy_context_free(tls_context); \
+   } while (0)
+#else
+#define TLS_PROXY_CONTEXT_FREE()		/* nothing */
+#endif
+
+#define SMTP_SESSION_ACTIVATE_ERR_RETURN() do { \
+	TLS_PROXY_CONTEXT_FREE(); \
+	return (0); \
+   } while (0)
+
+    /*
+     * Sanity check: if TLS is required, the cached properties must contain a
+     * TLS context.
+     */
+    if ((mp = vstream_memopen(endp_prop, O_RDONLY)) == 0
+	|| attr_scan_plain(mp, ATTR_FLAG_NONE,
+#ifdef USE_TLS
+			   RECV_ATTR_INT(SESS_ATTR_TLS_LEVEL,
+					 &tls->level),
+#endif
+			   RECV_ATTR_INT(SESS_ATTR_REUSE_COUNT,
+					 &reuse_count),
+			   RECV_ATTR_INT(SESS_ATTR_ENDP_FEATURES,
+					 &endp_features),
+			   RECV_ATTR_LONG(SESS_ATTR_EXPIRE_TIME,
+					  &expire_time),
+			   ATTR_TYPE_END) != 4
+#ifdef USE_TLS
+	|| ((tls->level > TLS_LEV_MAY
+	     || (tls->level == TLS_LEV_MAY && vstream_peek(mp) > 0))
+	    && attr_scan_plain(mp, ATTR_FLAG_NONE,
+			       RECV_ATTR_FUNC(tls_proxy_context_scan,
+					      (void *) &tls_context),
+			       ATTR_TYPE_END) != 1)
+#endif
+	|| vstream_fclose(mp) != 0) {
+	msg_warn("smtp_session_activate: bad cached endp properties");
+	SMTP_SESSION_ACTIVATE_ERR_RETURN();
+    }
+
+    /*
+     * Clobber the iterator's current nexthop, host and address fields with
+     * cached-connection information. This is done when a session is looked
+     * up by delivery request nexthop instead of address and port. It is the
+     * caller's responsibility to save and restore the delivery request
+     * nexthop with SMTP_ITER_SAVE_DEST() and SMTP_ITER_RESTORE_DEST().
+     * 
+     * TODO: Eliminate the duplication between SMTP_ITERATOR and SMTP_SESSION.
+     * 
+     * TODO: restore SASL username and password information so that we can
+     * correctly save a reused authenticated connection.
+     */
+    if (dest_prop && VSTRING_LEN(dest_prop)) {
+	if ((mp = vstream_memopen(dest_prop, O_RDONLY)) == 0
+	    || attr_scan_plain(mp, ATTR_FLAG_NONE,
+			       RECV_ATTR_STR(SESS_ATTR_DEST, iter->dest),
+			       RECV_ATTR_STR(SESS_ATTR_HOST, iter->host),
+			       RECV_ATTR_STR(SESS_ATTR_ADDR, iter->addr),
+			       RECV_ATTR_INT(SESS_ATTR_DEST_FEATURES,
+					     &dest_features),
+			       ATTR_TYPE_END) != 4
+	    || vstream_fclose(mp) != 0) {
+	    msg_warn("smtp_session_passivate: bad cached dest properties");
+	    SMTP_SESSION_ACTIVATE_ERR_RETURN();
+	}
+    } else {
+	dest_features = 0;
+    }
+#ifdef USE_TLS
+    if (msg_verbose)
+	msg_info("%s: tls_level=%d", myname, tls->level);
+#endif
+
+    /*
+     * Allright, bundle up what we have sofar.
+     */
+#define NO_FLAGS	0
+
+    session = smtp_session_alloc(vstream_fdopen(fd, O_RDWR), iter,
+				 (time_t) 0, NO_FLAGS);
+    session->features =
+	(endp_features | dest_features | SMTP_FEATURE_FROM_CACHE);
+#ifdef USE_TLS
+    session->tls_context = tls_context;
+#endif
+    CACHE_THIS_SESSION_UNTIL(expire_time);
+    session->reuse_count = ++reuse_count;
+
+    if (msg_verbose)
+	msg_info("%s: dest=%s host=%s addr=%s port=%u features=0x%x, "
+		 "ttl=%ld, reuse=%d",
+		 myname, STR(iter->dest), STR(iter->host),
+		 STR(iter->addr), ntohs(iter->port),
+		 endp_features | dest_features,
+		 (long) (expire_time - time((time_t *) 0)),
+		 reuse_count);
+
+#if USE_TLS
+    if (tls_context)
+	tls_log_summary(TLS_ROLE_CLIENT, TLS_USAGE_USED,
+			session->tls_context);
+#endif
+
+    return (session);
+}