Added silc_packet_send_va[_ext].
[silc.git] / lib / silccore / silcpacket.c
index 737c36f55a3f8a0008df1afc81e197da03a3ef12..2a2b9af18345a2079f7403b83c25dc48cd5c1b05 100644 (file)
@@ -54,22 +54,23 @@ struct SilcPacketStreamStruct {
   void *stream_context;                         /* Stream context */
   SilcBufferStruct inbuf;               /* In buffer */
   SilcBufferStruct outbuf;              /* Out buffer */
-  SilcUInt32 send_psn;                  /* Sending sequence */
-  SilcCipher send_key;                  /* Sending key */
-  SilcHmac send_hmac;                   /* Sending HMAC */
-  SilcUInt32 receive_psn;               /* Receiving sequence */
-  SilcCipher receive_key;               /* Receiving key */
-  SilcHmac receive_hmac;                /* Receiving HMAC */
+  SilcCipher send_key[2];               /* Sending key */
+  SilcHmac send_hmac[2];                /* Sending HMAC */
+  SilcCipher receive_key[2];            /* Receiving key */
+  SilcHmac receive_hmac[2];             /* Receiving HMAC */
   unsigned char *src_id;                /* Source ID */
   unsigned char *dst_id;                /* Destination ID */
+  SilcUInt32 send_psn;                  /* Sending sequence */
+  SilcUInt32 receive_psn;               /* Receiving sequence */
+  SilcAtomic8 refcnt;                   /* Reference counter */
   unsigned int src_id_len  : 6;
   unsigned int src_id_type : 2;
   unsigned int dst_id_len  : 6;
   unsigned int dst_id_type : 2;
-  SilcUInt8 refcnt;                     /* Reference counter */
   unsigned int is_router   : 1;                 /* Set if router stream */
   unsigned int destroyed   : 1;                 /* Set if destroyed */
   unsigned int iv_included : 1;          /* Set if IV included */
+  SilcUInt8 sid;                        /* Security ID, set if IV included */
 };
 
 /* Initial size of stream buffers */
@@ -80,7 +81,7 @@ struct SilcPacketStreamStruct {
 
 /* Minimum length of SILC Packet Header. */
 #define SILC_PACKET_MIN_HEADER_LEN 16
-#define SILC_PACKET_MIN_HEADER_LEN_IV 32
+#define SILC_PACKET_MIN_HEADER_LEN_IV 32 + 1
 
 /* Maximum padding length */
 #define SILC_PACKET_MAX_PADLEN 128
@@ -390,7 +391,7 @@ SilcPacketStream silc_packet_stream_create(SilcPacketEngine engine,
 
   ps->engine = engine;
   ps->stream = stream;
-  ps->refcnt++;
+  silc_atomic_init8(&ps->refcnt, 1);
 
   /* Allocate buffers */
   tmp = silc_malloc(SILC_PACKET_DEFAULT_SIZE);
@@ -427,7 +428,7 @@ void silc_packet_stream_destroy(SilcPacketStream stream)
   if (!stream)
     return;
 
-  if (stream->refcnt > 1) {
+  if (silc_atomic_get_int8(&stream->refcnt) > 1) {
     stream->destroyed = TRUE;
     return;
   }
@@ -450,6 +451,7 @@ void silc_packet_stream_destroy(SilcPacketStream stream)
   /* Destroy the underlaying stream */
   silc_stream_destroy(stream->stream);
 
+  silc_atomic_uninit8(&stream->refcnt);
   silc_dlist_uninit(stream->process);
   silc_mutex_free(stream->lock);
   silc_free(stream);
@@ -601,19 +603,14 @@ void silc_packet_stream_unlink(SilcPacketStream stream,
 
 void silc_packet_stream_ref(SilcPacketStream stream)
 {
-  silc_mutex_lock(stream->lock);
-  stream->refcnt++;
-  silc_mutex_unlock(stream->lock);
+  silc_atomic_add_int8(&stream->refcnt, 1);
 }
 
 /* Unreference packet stream */
 
 void silc_packet_stream_unref(SilcPacketStream stream)
 {
-  silc_mutex_lock(stream->lock);
-  stream->refcnt--;
-  silc_mutex_unlock(stream->lock);
-  if (stream->refcnt == 0)
+  if (silc_atomic_sub_int8(&stream->refcnt, 1) == 0)
     silc_packet_stream_destroy(stream);
 }
 
@@ -644,6 +641,18 @@ void *silc_packet_get_context(SilcPacketStream stream)
   return context;
 }
 
+/* Change underlaying stream */
+
+void silc_packet_stream_set_stream(SilcPacketStream ps,
+                                  SilcStream stream,
+                                  SilcSchedule schedule)
+{
+  if (ps->stream)
+    silc_stream_set_notifier(ps->stream, schedule, NULL, NULL);
+  ps->stream = stream;
+  silc_stream_set_notifier(ps->stream, schedule, silc_packet_stream_io, ps);
+}
+
 /* Return underlaying stream */
 
 SilcStream silc_packet_stream_get_stream(SilcPacketStream stream)
@@ -657,9 +666,29 @@ void silc_packet_set_ciphers(SilcPacketStream stream, SilcCipher send,
                             SilcCipher receive)
 {
   SILC_LOG_DEBUG(("Setting new ciphers to packet stream"));
+
   silc_mutex_lock(stream->lock);
-  stream->send_key = send;
-  stream->receive_key = receive;
+
+  /* In case IV Included is set, save the old key */
+  if (stream->iv_included) {
+    if (stream->send_key[1]) {
+      silc_cipher_free(stream->send_key[1]);
+      stream->send_key[1] = stream->send_key[0];
+    }
+    if (stream->receive_key[1]) {
+      silc_cipher_free(stream->receive_key[1]);
+      stream->receive_key[1] = stream->receive_key[0];
+    }
+  } else {
+    if (stream->send_key[0])
+      silc_cipher_free(stream->send_key[0]);
+    if (stream->send_key[1])
+      silc_cipher_free(stream->receive_key[0]);
+  }
+
+  stream->send_key[0] = send;
+  stream->receive_key[0] = receive;
+
   silc_mutex_unlock(stream->lock);
 }
 
@@ -668,15 +697,15 @@ void silc_packet_set_ciphers(SilcPacketStream stream, SilcCipher send,
 SilcBool silc_packet_get_ciphers(SilcPacketStream stream, SilcCipher *send,
                                 SilcCipher *receive)
 {
-  if (!stream->send_key && !stream->receive_key)
+  if (!stream->send_key[0] && !stream->receive_key[0])
     return FALSE;
 
   silc_mutex_lock(stream->lock);
 
   if (send)
-    *send = stream->send_key;
+    *send = stream->send_key[0];
   if (receive)
-    *receive = stream->receive_key;
+    *receive = stream->receive_key[0];
 
   silc_mutex_unlock(stream->lock);
 
@@ -689,9 +718,29 @@ void silc_packet_set_hmacs(SilcPacketStream stream, SilcHmac send,
                           SilcHmac receive)
 {
   SILC_LOG_DEBUG(("Setting new HMACs to packet stream"));
+
   silc_mutex_lock(stream->lock);
-  stream->send_hmac = send;
-  stream->receive_hmac = receive;
+
+  /* In case IV Included is set, save the old HMAC */
+  if (stream->iv_included) {
+    if (stream->send_hmac[1]) {
+      silc_hmac_free(stream->send_hmac[1]);
+      stream->send_hmac[1] = stream->send_hmac[0];
+    }
+    if (stream->receive_hmac[1]) {
+      silc_hmac_free(stream->receive_hmac[1]);
+      stream->receive_hmac[1] = stream->receive_hmac[0];
+    }
+  } else {
+    if (stream->send_hmac[0])
+      silc_hmac_free(stream->send_hmac[0]);
+    if (stream->receive_hmac[0])
+      silc_hmac_free(stream->receive_hmac[0]);
+  }
+
+  stream->send_hmac[0] = send;
+  stream->receive_hmac[0] = receive;
+
   silc_mutex_unlock(stream->lock);
 }
 
@@ -700,15 +749,15 @@ void silc_packet_set_hmacs(SilcPacketStream stream, SilcHmac send,
 SilcBool silc_packet_get_hmacs(SilcPacketStream stream, SilcHmac *send,
                               SilcHmac *receive)
 {
-  if (!stream->send_hmac && !stream->receive_hmac)
+  if (!stream->send_hmac[0] && !stream->receive_hmac[0])
     return FALSE;
 
   silc_mutex_lock(stream->lock);
 
   if (send)
-    *send = stream->send_hmac;
+    *send = stream->send_hmac[0];
   if (receive)
-    *receive = stream->receive_hmac;
+    *receive = stream->receive_hmac[0];
 
   silc_mutex_unlock(stream->lock);
 
@@ -766,6 +815,19 @@ SilcBool silc_packet_set_ids(SilcPacketStream stream,
   return TRUE;
 }
 
+/* Adds Security ID (SID) */
+
+SilcBool silc_packet_set_sid(SilcPacketStream stream, SilcUInt8 sid)
+{
+  if (!stream->iv_included)
+    return FALSE;
+
+  SILC_LOG_DEBUG(("Set packet stream %p SID to %d", stream, sid));
+
+  stream->sid = sid;
+  return TRUE;
+}
+
 /* Free packet */
 
 void silc_packet_free(SilcPacket packet)
@@ -774,19 +836,19 @@ void silc_packet_free(SilcPacket packet)
 
   SILC_LOG_DEBUG(("Freeing packet %p", packet));
 
-#if defined(SILC_DEBUG)
   /* Check for double free */
-  assert(packet->stream != NULL);
-#endif /* SILC_DEBUG */
-
-  silc_mutex_lock(stream->engine->lock);
+  SILC_ASSERT(packet->stream != NULL);
 
   packet->stream = NULL;
   packet->src_id = packet->dst_id = NULL;
   silc_buffer_reset(&packet->buffer);
 
+  silc_mutex_lock(stream->engine->lock);
+
   /* Put the packet back to freelist */
   silc_list_add(stream->engine->packet_pool, packet);
+  if (silc_list_count(stream->engine->packet_pool) == 1)
+    silc_list_start(stream->engine->packet_pool);
 
   silc_mutex_unlock(stream->engine->lock);
 }
@@ -839,12 +901,12 @@ static SilcBool silc_packet_send_raw(SilcPacketStream stream,
                                     SilcCipher cipher,
                                     SilcHmac hmac)
 {
-  unsigned char tmppad[SILC_PACKET_MAX_PADLEN], iv[32], psn[4];
+  unsigned char tmppad[SILC_PACKET_MAX_PADLEN], iv[33], psn[4];
   int block_len = (cipher ? silc_cipher_get_block_len(cipher) : 0);
   int i, enclen, truelen, padlen, ivlen = 0, psnlen = 0;
   SilcBufferStruct packet;
 
-  SILC_LOG_DEBUG(("Sending packet %s (%d) flags %d, src %d dst %d,"
+  SILC_LOG_DEBUG(("Sending packet %s (%d) flags %d, src %d dst %d, "
                  "data len %d", silc_get_packet_name(type), stream->send_psn,
                  flags, src_id_type, dst_id_type, data_len));
 
@@ -856,11 +918,12 @@ static SilcBool silc_packet_send_raw(SilcPacketStream stream,
   enclen = truelen = (data_len + SILC_PACKET_HEADER_LEN +
                      src_id_len + dst_id_len);
 
-  /* If IV is included, the IV and sequence number is added to packet */
+  /* If IV is included, the SID, IV and sequence number is added to packet */
   if (stream->iv_included && cipher) {
-    ivlen = block_len;
     psnlen = sizeof(psn);
-    memcpy(iv, silc_cipher_get_iv(cipher), block_len);
+    ivlen = block_len + 1;
+    iv[0] = stream->sid;
+    memcpy(iv + 1, silc_cipher_get_iv(cipher), block_len);
   }
 
   /* We automatically figure out the packet structure from the packet
@@ -910,8 +973,8 @@ static SilcBool silc_packet_send_raw(SilcPacketStream stream,
   /* Create the packet.  This creates the SILC header, adds padding, and
      the actual packet data. */
   i = silc_buffer_format(&packet,
-                        SILC_STR_UI_XNSTRING(iv, ivlen),
-                        SILC_STR_UI_XNSTRING(psn, psnlen),
+                        SILC_STR_DATA(iv, ivlen),
+                        SILC_STR_DATA(psn, psnlen),
                         SILC_STR_UI_SHORT(truelen),
                         SILC_STR_UI_CHAR(flags),
                         SILC_STR_UI_CHAR(type),
@@ -920,11 +983,11 @@ static SilcBool silc_packet_send_raw(SilcPacketStream stream,
                         SILC_STR_UI_CHAR(src_id_len),
                         SILC_STR_UI_CHAR(dst_id_len),
                         SILC_STR_UI_CHAR(src_id_type),
-                        SILC_STR_UI_XNSTRING(src_id, src_id_len),
+                        SILC_STR_DATA(src_id, src_id_len),
                         SILC_STR_UI_CHAR(dst_id_type),
-                        SILC_STR_UI_XNSTRING(dst_id, dst_id_len),
-                        SILC_STR_UI_XNSTRING(tmppad, padlen),
-                        SILC_STR_UI_XNSTRING(data, data_len),
+                        SILC_STR_DATA(dst_id, dst_id_len),
+                        SILC_STR_DATA(tmppad, padlen),
+                        SILC_STR_DATA(data, data_len),
                         SILC_STR_END);
   if (i < 0) {
     silc_mutex_unlock(stream->lock);
@@ -1008,8 +1071,8 @@ SilcBool silc_packet_send(SilcPacketStream stream,
                              stream->dst_id,
                              stream->dst_id_len,
                              data, data_len,
-                             stream->send_key,
-                             stream->send_hmac);
+                             stream->send_key[0],
+                             stream->send_hmac[0]);
 }
 
 /* Sends a packet, extended routine */
@@ -1041,10 +1104,65 @@ SilcBool silc_packet_send_ext(SilcPacketStream stream,
                              dst_id ? dst_id_data : stream->dst_id,
                              dst_id ? dst_id_len : stream->dst_id_len,
                              data, data_len,
-                             cipher ? cipher : stream->send_key,
-                             hmac ? hmac : stream->send_hmac);
+                             cipher ? cipher : stream->send_key[0],
+                             hmac ? hmac : stream->send_hmac[0]);
+}
+
+/* Sends packet after formatting the arguments to buffer */
+
+SilcBool silc_packet_send_va(SilcPacketStream stream,
+                            SilcPacketType type, SilcPacketFlags flags, ...)
+{
+  SilcBufferStruct buf;
+  SilcBool ret;
+  va_list va;
+
+  va_start(va, flags);
+
+  memset(&buf, 0, sizeof(buf));
+  if (silc_buffer_format_vp(&buf, va) < 0) {
+    va_end(va);
+    return FALSE;
+  }
+
+  ret = silc_packet_send(stream, type, flags, silc_buffer_data(&buf),
+                        silc_buffer_len(&buf));
+
+  silc_buffer_purge(&buf);
+  va_end(va);
+
+  return ret;
 }
 
+/* Sends packet after formatting the arguments to buffer, extended routine */
+
+SilcBool silc_packet_send_va_ext(SilcPacketStream stream,
+                                SilcPacketType type, SilcPacketFlags flags,
+                                SilcIdType src_id_type, void *src_id,
+                                SilcIdType dst_id_type, void *dst_id,
+                                SilcCipher cipher, SilcHmac hmac, ...)
+{
+  SilcBufferStruct buf;
+  SilcBool ret;
+  va_list va;
+
+  va_start(va, hmac);
+
+  memset(&buf, 0, sizeof(buf));
+  if (silc_buffer_format_vp(&buf, va) < 0) {
+    va_end(va);
+    return FALSE;
+  }
+
+  ret = silc_packet_send_ext(stream, type, flags, src_id_type, src_id,
+                            dst_id_type, dst_id, silc_buffer_data(&buf),
+                            silc_buffer_len(&buf), cipher, hmac);
+
+  silc_buffer_purge(&buf);
+  va_end(va);
+
+  return TRUE;
+}
 
 /***************************** Packet Receiving *****************************/
 
@@ -1144,18 +1262,19 @@ static SilcBool silc_packet_parse(SilcPacket packet)
   SilcBuffer buffer = &packet->buffer;
   SilcUInt8 padlen = (SilcUInt8)buffer->data[4];
   SilcUInt8 src_id_len, dst_id_len, src_id_type, dst_id_type;
-  int len, ret;
+  int ret;
 
   SILC_LOG_DEBUG(("Parsing incoming packet"));
 
   /* Parse the buffer.  This parses the SILC header of the packet. */
-  len = silc_buffer_unformat(buffer,
+  ret = silc_buffer_unformat(buffer,
+                            SILC_STR_ADVANCE,
                             SILC_STR_OFFSET(6),
                             SILC_STR_UI_CHAR(&src_id_len),
                             SILC_STR_UI_CHAR(&dst_id_len),
                             SILC_STR_UI_CHAR(&src_id_type),
                             SILC_STR_END);
-  if (len == -1) {
+  if (ret == -1) {
     SILC_LOG_ERROR(("Malformed packet header, packet dropped"));
     return FALSE;
   }
@@ -1168,12 +1287,10 @@ static SilcBool silc_packet_parse(SilcPacket packet)
   }
 
   ret = silc_buffer_unformat(buffer,
-                            SILC_STR_OFFSET(len),
-                            SILC_STR_UI_XNSTRING(&packet->src_id,
-                                                 src_id_len),
+                            SILC_STR_ADVANCE,
+                            SILC_STR_DATA(&packet->src_id, src_id_len),
                             SILC_STR_UI_CHAR(&dst_id_type),
-                            SILC_STR_UI_XNSTRING(&packet->dst_id,
-                                                 dst_id_len),
+                            SILC_STR_DATA(&packet->dst_id, dst_id_len),
                             SILC_STR_OFFSET(padlen),
                             SILC_STR_END);
   if (ret == -1) {
@@ -1193,12 +1310,9 @@ static SilcBool silc_packet_parse(SilcPacket packet)
   packet->src_id_type = src_id_type;
   packet->dst_id_type = dst_id_type;
 
-  SILC_LOG_HEXDUMP(("Parsed packet, len %d", silc_buffer_len(buffer)),
-                  buffer->data, silc_buffer_len(buffer));
-
-  /* Pull SILC header and padding from packet to get the data payload */
-  silc_buffer_pull(buffer, SILC_PACKET_HEADER_LEN +
-                  packet->src_id_len + packet->dst_id_len + padlen);
+  SILC_LOG_HEXDUMP(("Parsed packet, len %d", silc_buffer_headlen(buffer) +
+                  silc_buffer_len(buffer)), buffer->head,
+                  silc_buffer_headlen(buffer) + silc_buffer_len(buffer));
 
   SILC_LOG_DEBUG(("Incoming packet type: %d (%s)", packet->type,
                  silc_get_packet_name(packet->type)));
@@ -1217,9 +1331,9 @@ static void silc_packet_dispatch(SilcPacket packet)
 
   /* Parse the packet */
   if (!silc_packet_parse(packet)) {
-    silc_mutex_unlock(packet->stream->lock);
+    silc_mutex_unlock(stream->lock);
     SILC_PACKET_CALLBACK_ERROR(stream, SILC_PACKET_ERR_MALFORMED);
-    silc_mutex_lock(packet->stream->lock);
+    silc_mutex_lock(stream->lock);
     silc_packet_free(packet);
     return;
   }
@@ -1229,13 +1343,13 @@ static void silc_packet_dispatch(SilcPacket packet)
   if (!stream->process) {
     /* Send to default processor as no others exist */
     SILC_LOG_DEBUG(("Dispatching packet to default callbacks"));
-    silc_mutex_unlock(packet->stream->lock);
+    silc_mutex_unlock(stream->lock);
     if (!stream->engine->callbacks->
        packet_receive(stream->engine, stream, packet,
                       stream->engine->callback_context,
                       stream->stream_context))
       silc_packet_free(packet);
-    silc_mutex_lock(packet->stream->lock);
+    silc_mutex_lock(stream->lock);
     return;
   }
 
@@ -1247,43 +1361,43 @@ static void silc_packet_dispatch(SilcPacket packet)
     if (!default_sent && p->priority <= 0) {
       SILC_LOG_DEBUG(("Dispatching packet to default callbacks"));
       default_sent = TRUE;
-      silc_mutex_unlock(packet->stream->lock);
+      silc_mutex_unlock(stream->lock);
       if (stream->engine->callbacks->
          packet_receive(stream->engine, stream, packet,
                         stream->engine->callback_context,
                         stream->stream_context)) {
-       silc_mutex_lock(packet->stream->lock);
+       silc_mutex_lock(stream->lock);
        return;
       }
-      silc_mutex_lock(packet->stream->lock);
+      silc_mutex_lock(stream->lock);
     }
 
     /* Send to processor */
     if (!p->types) {
       /* Send all packet types */
       SILC_LOG_DEBUG(("Dispatching packet to %p callbacks", p->callbacks));
-      silc_mutex_unlock(packet->stream->lock);
+      silc_mutex_unlock(stream->lock);
       if (p->callbacks->packet_receive(stream->engine, stream, packet,
                                       p->callback_context,
                                       stream->stream_context)) {
-       silc_mutex_lock(packet->stream->lock);
+       silc_mutex_lock(stream->lock);
        return;
       }
-      silc_mutex_lock(packet->stream->lock);
+      silc_mutex_lock(stream->lock);
     } else {
       /* Send specific types */
       for (pt = p->types; *pt; pt++) {
        if (*pt != packet->type)
          continue;
        SILC_LOG_DEBUG(("Dispatching packet to %p callbacks", p->callbacks));
-       silc_mutex_unlock(packet->stream->lock);
+       silc_mutex_unlock(stream->lock);
        if (p->callbacks->packet_receive(stream->engine, stream, packet,
                                         p->callback_context,
                                         stream->stream_context)) {
-         silc_mutex_lock(packet->stream->lock);
+         silc_mutex_lock(stream->lock);
          return;
        }
-       silc_mutex_lock(packet->stream->lock);
+       silc_mutex_lock(stream->lock);
        break;
       }
     }
@@ -1292,15 +1406,15 @@ static void silc_packet_dispatch(SilcPacket packet)
   if (!default_sent) {
     /* Send to default processor as it has not been sent yet */
     SILC_LOG_DEBUG(("Dispatching packet to default callbacks"));
-    silc_mutex_unlock(packet->stream->lock);
+    silc_mutex_unlock(stream->lock);
     if (stream->engine->callbacks->
        packet_receive(stream->engine, stream, packet,
                       stream->engine->callback_context,
                       stream->stream_context)) {
-      silc_mutex_lock(packet->stream->lock);
+      silc_mutex_lock(stream->lock);
       return;
     }
-    silc_mutex_lock(packet->stream->lock);
+    silc_mutex_lock(stream->lock);
   }
 
   /* If we got here, no one wanted the packet, so drop it */
@@ -1312,7 +1426,10 @@ static void silc_packet_dispatch(SilcPacket packet)
 
 static void silc_packet_read_process(SilcPacketStream stream)
 {
+  SilcCipher cipher;
+  SilcHmac hmac;
   SilcPacket packet;
+  SilcUInt8 sid;
   SilcUInt16 packetlen;
   SilcUInt32 paddedlen, mac_len, block_len, ivlen, psnlen;
   unsigned char tmp[SILC_PACKET_MIN_HEADER_LEN], *header;
@@ -1323,33 +1440,56 @@ static void silc_packet_read_process(SilcPacketStream stream)
   /* Parse the packets from the data */
   while (silc_buffer_len(&stream->inbuf) > 0) {
     ivlen = psnlen = 0;
+    cipher = stream->receive_key[0];
+    hmac = stream->receive_hmac[0];
 
     if (silc_buffer_len(&stream->inbuf) <
-       stream->iv_included ? SILC_PACKET_MIN_HEADER_LEN_IV :
-       SILC_PACKET_MIN_HEADER_LEN) {
+       (stream->iv_included ? SILC_PACKET_MIN_HEADER_LEN_IV :
+        SILC_PACKET_MIN_HEADER_LEN)) {
       SILC_LOG_DEBUG(("Partial packet in queue, waiting for the rest"));
       return;
     }
 
-    if (stream->receive_hmac)
-      mac_len = silc_hmac_len(stream->receive_hmac);
+    if (hmac)
+      mac_len = silc_hmac_len(hmac);
     else
       mac_len = 0;
 
     /* Decrypt first block of the packet to get the length field out */
-    if (stream->receive_key) {
-      block_len = silc_cipher_get_block_len(stream->receive_key);
+    if (cipher) {
+      block_len = silc_cipher_get_block_len(cipher);
 
       if (stream->iv_included) {
-       /* IV is included in the ciphertext */
-       memcpy(iv, stream->inbuf.data, block_len);
-       ivlen = block_len;
+       /* SID, IV and sequence number is included in the ciphertext */
+       sid = (SilcUInt8)stream->inbuf.data[0];
+       memcpy(iv, stream->inbuf.data + 1, block_len);
+       ivlen = block_len + 1;
        psnlen = 4;
-      } else
-       memcpy(iv, silc_cipher_get_iv(stream->receive_key), block_len);
 
-      silc_cipher_decrypt(stream->receive_key, stream->inbuf.data + ivlen,
-                         tmp, block_len, iv);
+       /* Check SID, and get correct decryption key */
+       if (sid != stream->sid) {
+         /* If SID is recent get the previous key and use it */
+         if (sid > 0 && stream->sid > 0 && stream->sid - 1 == sid &&
+             stream->receive_key[1] && !stream->receive_hmac[1]) {
+           cipher = stream->receive_key[1];
+           hmac = stream->receive_hmac[1];
+         } else {
+           /* The SID is unknown, drop rest of the data in buffer */
+           SILC_LOG_DEBUG(("Unknown Security ID %d in packet, expected %d",
+                           sid, stream->sid));
+           silc_mutex_unlock(stream->lock);
+           SILC_PACKET_CALLBACK_ERROR(stream, SILC_PACKET_ERR_UNKNOWN_SID);
+           silc_mutex_lock(stream->lock);
+           silc_buffer_reset(&stream->inbuf);
+           return;
+         }
+       }
+      } else {
+       memcpy(iv, silc_cipher_get_iv(cipher), block_len);
+      }
+
+      silc_cipher_decrypt(cipher, stream->inbuf.data + ivlen, tmp,
+                         block_len, iv);
 
       header = tmp;
       if (stream->iv_included) {
@@ -1385,7 +1525,7 @@ static void silc_packet_read_process(SilcPacketStream stream)
     }
 
     /* Check MAC of the packet */
-    if (!silc_packet_check_mac(stream->receive_hmac, stream->inbuf.data,
+    if (!silc_packet_check_mac(hmac, stream->inbuf.data,
                               paddedlen + ivlen,
                               stream->inbuf.data + ivlen + paddedlen,
                               packet_seq, stream->receive_psn)) {
@@ -1455,10 +1595,10 @@ static void silc_packet_read_process(SilcPacketStream stream)
     silc_buffer_put(&packet->buffer, (stream->inbuf.data + ivlen +
                                      psnlen + (block_len - psnlen)),
                    paddedlen - ivlen - psnlen - (block_len - psnlen));
-    if (stream->receive_key) {
-      silc_cipher_set_iv(stream->receive_key, iv);
-      ret = silc_packet_decrypt(stream->receive_key, stream->receive_hmac,
-                               stream->receive_psn, &packet->buffer, normal);
+    if (cipher) {
+      silc_cipher_set_iv(cipher, iv);
+      ret = silc_packet_decrypt(cipher, hmac, stream->receive_psn,
+                               &packet->buffer, normal);
       if (ret < 0) {
        silc_mutex_unlock(stream->lock);
        SILC_PACKET_CALLBACK_ERROR(stream, SILC_PACKET_ERR_DECRYPTION_FAILED);