+/* Parses list of channel payloads returning list of payloads. */
+
+SilcDList silc_channel_payload_parse_list(const unsigned char *payload,
+ SilcUInt32 payload_len)
+{
+ SilcBufferStruct buffer;
+ SilcDList list;
+ SilcChannelPayload new;
+ int len, ret;
+
+ SILC_LOG_DEBUG(("Parsing channel payload list"));
+
+ silc_buffer_set(&buffer, (unsigned char *)payload, payload_len);
+ list = silc_dlist_init();
+
+ while (buffer.len) {
+ new = silc_calloc(1, sizeof(*new));
+ ret = silc_buffer_unformat(&buffer,
+ SILC_STR_UI16_NSTRING_ALLOC(&new->channel_name,
+ &new->name_len),
+ SILC_STR_UI16_NSTRING_ALLOC(&new->channel_id,
+ &new->id_len),
+ SILC_STR_UI_INT(&new->mode),
+ SILC_STR_END);
+ if (ret == -1)
+ goto err;
+
+ if ((new->name_len < 1 || new->name_len > buffer.len) ||
+ (new->id_len < 1 || new->id_len > buffer.len)) {
+ SILC_LOG_ERROR(("Incorrect channel payload in packet, packet dropped"));
+ goto err;
+ }
+
+ len = 2 + new->name_len + 2 + new->id_len + 4;
+ if (buffer.len < len)
+ break;
+ silc_buffer_pull(&buffer, len);
+
+ silc_dlist_add(list, new);
+ }
+
+ return list;
+
+ err:
+ silc_channel_payload_list_free(list);
+ return NULL;
+}
+
+/* Encode new channel payload and returns it as buffer. */
+
+SilcBuffer silc_channel_payload_encode(const unsigned char *channel_name,
+ SilcUInt16 channel_name_len,
+ const unsigned char *channel_id,
+ SilcUInt32 channel_id_len,
+ SilcUInt32 mode)
+{
+ SilcBuffer buffer;
+
+ SILC_LOG_DEBUG(("Encoding message payload"));
+
+ buffer = silc_buffer_alloc(2 + channel_name_len + 2 + channel_id_len + 4);
+ silc_buffer_pull_tail(buffer, SILC_BUFFER_END(buffer));
+
+ /* Encode the Channel Payload */
+ silc_buffer_format(buffer,
+ SILC_STR_UI_SHORT(channel_name_len),
+ SILC_STR_UI_XNSTRING(channel_name, channel_name_len),
+ SILC_STR_UI_SHORT(channel_id_len),
+ SILC_STR_UI_XNSTRING(channel_id, channel_id_len),
+ SILC_STR_UI_INT(mode),
+ SILC_STR_END);
+
+ return buffer;
+}
+
+/* Frees Channel Payload */
+
+void silc_channel_payload_free(SilcChannelPayload payload)
+{
+ silc_free(payload->channel_name);
+ silc_free(payload->channel_id);
+ silc_free(payload);
+}
+
+/* Free's list of Channel Payloads */
+
+void silc_channel_payload_list_free(SilcDList list)
+{
+ SilcChannelPayload entry;
+
+ silc_dlist_start(list);
+ while ((entry = silc_dlist_get(list)) != SILC_LIST_END) {
+ silc_free(entry->channel_name);
+ silc_free(entry->channel_id);
+ silc_dlist_del(list, entry);
+ silc_free(entry);
+ }
+
+ silc_dlist_uninit(list);
+}
+
+/* Return the channel name */
+
+unsigned char *silc_channel_get_name(SilcChannelPayload payload,
+ SilcUInt32 *channel_name_len)
+{
+ if (channel_name_len)
+ *channel_name_len = payload->name_len;
+
+ return payload->channel_name;
+}
+
+/* Return the channel ID */
+
+unsigned char *silc_channel_get_id(SilcChannelPayload payload,
+ SilcUInt32 *channel_id_len)
+{
+ if (channel_id_len)
+ *channel_id_len = payload->id_len;
+
+ return payload->channel_id;
+}
+
+/* Return the channel ID as parsed ID. */
+
+SilcChannelID *silc_channel_get_id_parse(SilcChannelPayload payload)
+{
+ return silc_id_str2id(payload->channel_id, payload->id_len,
+ SILC_ID_CHANNEL);
+}
+
+/* Return the mode. The mode is arbitrary. It can be the mode of the
+ channel or perhaps the mode of the client on the channel. The protocol
+ dictates what the usage of the mode is in different circumstances. */
+
+SilcUInt32 silc_channel_get_mode(SilcChannelPayload payload)
+{
+ return payload->mode;
+}
+
+/******************************************************************************
+
+ Channel Message Payload
+
+******************************************************************************/
+
+#define SILC_CHANNEL_MESSAGE_PAD(__payloadlen) (16 - (__payloadlen) % 16)
+
+/* Channel Message Payload structure. Contents of this structure is parsed
+ from SILC packets. */
+struct SilcChannelMessagePayloadStruct {
+ SilcMessageFlags flags;
+ SilcUInt16 data_len;
+ unsigned char *data;
+ unsigned char *mac;
+ unsigned char *iv;
+};
+
+/* Decrypts the channel message payload. 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
+ successful and we have the channel message ready to be displayed. */
+
+bool silc_channel_message_payload_decrypt(unsigned char *data,
+ size_t data_len,
+ SilcCipher cipher,
+ SilcHmac hmac)
+{
+ SilcUInt32 iv_len, mac_len;
+ unsigned char *end, *mac, mac2[32];
+ unsigned char *dst, iv[SILC_CIPHER_MAX_IV_SIZE];
+
+ /* Push the IV out of the packet, and copy the IV since we do not want
+ to modify the original data buffer. */
+ end = data + data_len;
+ iv_len = silc_cipher_get_block_len(cipher);
+ memcpy(iv, end - iv_len, iv_len);
+
+ /* Allocate destination decryption buffer since we do not want to modify
+ the original data buffer, since we might want to call this function
+ many times for same payload. */
+ if (hmac)
+ dst = silc_calloc(data_len - iv_len, sizeof(*dst));
+ else
+ dst = data;
+
+ /* Decrypt the channel message */
+ silc_cipher_decrypt(cipher, data, dst, data_len - iv_len, iv);
+
+ if (hmac) {
+ /* Take the MAC */
+ end = dst + (data_len - iv_len);
+ mac_len = silc_hmac_len(hmac);
+ mac = (end - mac_len);
+
+ /* Check the MAC of the message */
+ SILC_LOG_DEBUG(("Checking channel message MACs"));
+ silc_hmac_make(hmac, dst, (data_len - iv_len - mac_len), mac2, &mac_len);
+ if (memcmp(mac, mac2, mac_len)) {
+ SILC_LOG_DEBUG(("Channel message MACs does not match"));
+ silc_free(dst);
+ return FALSE;
+ }
+ SILC_LOG_DEBUG(("MAC is Ok"));
+
+ /* Now copy the decrypted data into the buffer since it is verified
+ it decrypted correctly. */
+ memcpy(data, dst, data_len - iv_len);
+ memset(dst, 0, data_len - iv_len);
+ silc_free(dst);
+ }
+
+ return TRUE;
+}
+
+/* Parses channel message payload returning new channel payload structure.
+ This also decrypts it and checks the MAC. */
+
+SilcChannelMessagePayload
+silc_channel_message_payload_parse(unsigned char *payload,
+ SilcUInt32 payload_len,
+ SilcCipher cipher,
+ SilcHmac hmac)
+{
+ SilcBufferStruct buffer;
+ SilcChannelMessagePayload new;
+ int ret;
+ SilcUInt32 iv_len, mac_len;
+
+ SILC_LOG_DEBUG(("Parsing channel message payload"));
+
+ silc_buffer_set(&buffer, payload, payload_len);
+
+ /* Decrypt the payload */
+ ret = silc_channel_message_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));
+
+ /* Parse the Channel Message Payload. Ignore the padding. */
+ ret = silc_buffer_unformat(&buffer,
+ SILC_STR_UI_SHORT(&new->flags),
+ SILC_STR_UI16_NSTRING_ALLOC(&new->data,
+ &new->data_len),
+ SILC_STR_UI16_NSTRING(NULL, NULL),
+ SILC_STR_UI_XNSTRING(&new->mac, mac_len),
+ SILC_STR_UI_XNSTRING(&new->iv, iv_len),
+ SILC_STR_END);
+ if (ret == -1)
+ goto err;
+
+ if (new->data_len > buffer.len) {
+ SILC_LOG_ERROR(("Incorrect channel message payload in packet, "
+ "packet dropped"));
+ goto err;
+ }
+
+ return new;
+
+ err:
+ silc_channel_message_payload_free(new);
+ return NULL;
+}
+
+/* Encodes channel message payload into a buffer and returns it. This is used
+ to add channel message payload into a packet. As the channel payload is