updates.

[silc.git] / lib / silccore / silcchannel.c

diff --git a/lib/silccore/silcchannel.c b/lib/silccore/silcchannel.c
index b3956cd291408c6193f459678d14673d57382c9b..433236eb4be27dacb695362e8938fb0da334039c 100644 (file)
--- a/lib/silccore/silcchannel.c
+++ b/lib/silccore/silcchannel.c
@@ -38,48 +38,68 @@ struct SilcChannelPayloadStruct {
   unsigned char *iv;
 };
 
-/* Parses channel payload returning new channel payload structure. This
-   also decrypts it and checks the MAC. */
+/* Decrypts the channel message payload. */
 
-SilcChannelPayload silc_channel_payload_parse(SilcBuffer buffer,
-                                             SilcCipher cipher,
-                                             SilcHmac hmac)
+int silc_channel_payload_decrypt(unsigned char *data,
+                                size_t data_len,
+                                SilcCipher cipher,
+                                SilcHmac hmac)
 {
-  SilcChannelPayload new;
-  int ret;
   unsigned int iv_len, mac_len;
-  unsigned char *mac, mac2[32];
-
-  SILC_LOG_DEBUG(("Parsing channel payload"));
+  unsigned char *end, *mac, mac2[32];
 
   /* Decrypt the channel message. First push the IV out of the packet.
      The IV is used in the decryption process. Then decrypt the message.
      After decyprtion, take the MAC from the decrypted packet, compute MAC
      and compare the MACs.  If they match, the decryption was successfull
      and we have the channel message ready to be displayed. */
+  end = data + data_len;
 
-  /* Push the IV out of the packet (it will be in buffer->tail) */
+  /* Push the IV out of the packet */
   iv_len = silc_cipher_get_block_len(cipher);
-  silc_buffer_push_tail(buffer, iv_len);
 
   /* Decrypt the channel message */
-  silc_cipher_decrypt(cipher, buffer->data, buffer->data,
-                     buffer->len, buffer->tail);
+  silc_cipher_decrypt(cipher, data, data, data_len - iv_len, (end - iv_len));
 
   /* Take the MAC */
-  mac_len = silc_hmac_len(hmac);
-  silc_buffer_push_tail(buffer, mac_len);
-  mac = buffer->tail;
-
-  /* Check the MAC of the message */
-  SILC_LOG_DEBUG(("Checking channel message MACs"));
-  silc_hmac_make(hmac, buffer->data, buffer->len, mac2, &mac_len);
-  if (memcmp(mac, mac2, mac_len)) {
-    SILC_LOG_DEBUG(("Channel message MACs does not match"));
-    return NULL;
+  if (hmac) {
+    mac_len = silc_hmac_len(hmac);
+    mac = (end - iv_len - mac_len);
+
+    /* Check the MAC of the message */
+    SILC_LOG_DEBUG(("Checking channel message MACs"));
+    silc_hmac_make(hmac, data, (data_len - iv_len - mac_len), mac2, &mac_len);
+    if (memcmp(mac, mac2, mac_len)) {
+      SILC_LOG_DEBUG(("Channel message MACs does not match"));
+      return FALSE;
+    }
+    SILC_LOG_DEBUG(("MAC is Ok"));
   }
-  SILC_LOG_DEBUG(("MAC is Ok"));
-  silc_buffer_pull_tail(buffer, iv_len + mac_len);
+
+  return TRUE;
+}
+
+/* Parses channel payload returning new channel payload structure. This
+   also decrypts it and checks the MAC. */
+
+SilcChannelPayload silc_channel_payload_parse(SilcBuffer buffer,
+                                             SilcCipher cipher,
+                                             SilcHmac hmac)
+{
+  SilcChannelPayload new;
+  int ret;
+  unsigned int iv_len, mac_len;
+
+  SILC_LOG_DEBUG(("Parsing channel payload"));
+
+  /* Decrypt the payload */
+  ret = silc_channel_payload_decrypt(buffer->data, buffer->len,
+                                    cipher, hmac);
+  if (ret == FALSE)
+    return NULL;
+
+  iv_len = silc_cipher_get_block_len(cipher);
+  mac_len = silc_hmac_len(hmac);
 
   new = silc_calloc(1, sizeof(*new));
 
@@ -176,8 +196,10 @@ SilcBuffer silc_channel_payload_encode(unsigned short data_len,
 void silc_channel_payload_free(SilcChannelPayload payload)
 {
   if (payload) {
-    if (payload->data)
+    if (payload->data) {
+      memset(payload->data, 0, payload->data_len);
       silc_free(payload->data);
+    }
     silc_free(payload);
   }
 }