/*
- silcpacket.c
+ silcpacket.c
- Author: Pekka Riikonen <priikone@poseidon.pspt.fi>
+ Author: Pekka Riikonen <priikone@silcnet.org>
- Copyright (C) 1997 - 2000 Pekka Riikonen
+ Copyright (C) 1997 - 2001 Pekka Riikonen
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
- the Free Software Foundation; either version 2 of the License, or
- (at your option) any later version.
-
+ the Free Software Foundation; version 2 of the License.
+
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
/*
* Created: Fri Jul 25 18:52:14 1997
*/
-/*
- * $Id$
- * $Log$
- * Revision 1.1.1.1 2000/06/27 11:36:55 priikone
- * Importet from internal CVS/Added Log headers.
- *
- *
- */
+/* $Id$ */
#include "silcincludes.h"
-/* Writes data from encrypted buffer to the socket connection. If the
- data cannot be written at once, it will be written later with a timeout.
- The data is written from the data section of the buffer, not from head
- or tail section. This automatically pulls the data section towards end
- after writing the data. */
+/******************************************************************************
-int silc_packet_write(int sock, SilcBuffer src)
+ Packet Sending Routines
+
+******************************************************************************/
+
+/* Actually sends the packet. This flushes the connections outgoing data
+ buffer. If data is sent directly to the network this returns the bytes
+ written, if error occured this returns -1 and if the data could not
+ be written directly to the network at this time this returns -2, in
+ which case the data should be queued by the caller and sent at some
+ later time. If `force_send' is TRUE this attempts to write the data
+ directly to the network, if FALSE, this returns -2. */
+
+int silc_packet_send(SilcSocketConnection sock, bool force_send)
{
- int ret = 0;
+ SILC_LOG_DEBUG(("Sending packet to %s:%d [%s]", sock->hostname,
+ sock->port,
+ (sock->type == SILC_SOCKET_TYPE_UNKNOWN ? "Unknown" :
+ sock->type == SILC_SOCKET_TYPE_CLIENT ? "Client" :
+ sock->type == SILC_SOCKET_TYPE_SERVER ? "Server" :
+ "Router")));
- SILC_LOG_DEBUG(("Writing data to socket %d", sock));
+ /* Send now if forced to do so */
+ if (force_send == TRUE) {
+ int ret;
- if (src->len > 0) {
- ret = write(sock, src->data, src->len);
- if (ret < 0) {
- if (errno == EAGAIN) {
- SILC_LOG_DEBUG(("Could not write immediately, will do it later"));
- return -2;
- }
- SILC_LOG_ERROR(("Cannot write to socket: %s", strerror(errno)));
- return -1;
+ SILC_LOG_DEBUG(("Forcing packet send, packet sent immediately"));
+
+ /* Write to network */
+ ret = silc_socket_write(sock);
+
+ if (ret == -1) {
+ SILC_LOG_ERROR(("Error sending packet, dropped: %s",
+ strerror(errno)));
}
+ if (ret != -2)
+ return ret;
+
+ SILC_LOG_DEBUG(("Could not force the send, packet put to queue"));
+ }
+
+ SILC_LOG_DEBUG(("Packet in queue"));
+
+ return -2;
+}
+
+/* Encrypts a packet. This also creates HMAC of the packet before
+ encryption and adds the HMAC at the end of the buffer. This assumes
+ that there is enough free space at the end of the buffer to add the
+ computed HMAC. This is the normal way of encrypting packets, if some
+ other process of HMAC computing and encryption is needed this function
+ cannot be used. */
- silc_buffer_pull(src, ret);
+void silc_packet_encrypt(SilcCipher cipher, SilcHmac hmac, SilcUInt32 sequence,
+ SilcBuffer buffer, SilcUInt32 len)
+{
+ unsigned char mac[32];
+ SilcUInt32 mac_len;
+
+ /* Compute HMAC. This assumes that HMAC is created from the entire
+ data area thus this uses the length found in buffer, not the length
+ sent as argument. */
+ if (hmac) {
+ unsigned char psn[4];
+
+ silc_hmac_init(hmac);
+ SILC_PUT32_MSB(sequence, psn);
+ silc_hmac_update(hmac, psn, 4);
+ silc_hmac_update(hmac, buffer->data, buffer->len);
+ silc_hmac_final(hmac, mac, &mac_len);
+ silc_buffer_put_tail(buffer, mac, mac_len);
+ memset(mac, 0, sizeof(mac));
}
- SILC_LOG_DEBUG(("Wrote data %d bytes", ret));
+ /* Encrypt the data area of the packet. */
+ if (cipher) {
+ SILC_LOG_DEBUG(("Encrypting packet, cipher %s, len %d",
+ cipher->cipher->name, len));
+ silc_cipher_encrypt(cipher, buffer->data, buffer->data, len, cipher->iv);
+ }
- return ret;
+ /* Pull the HMAC into the visible data area in the buffer */
+ if (hmac)
+ silc_buffer_pull_tail(buffer, mac_len);
}
-/* Reads data from the socket connection into the incoming data buffer.
- However, this does not parse the packet, it only reads some amount from
- the network. If there are more data available that can be read at a time
- the rest of the data will be read later with a timeout and only after
- that the packet is ready to be parsed.
+/* Assembles a new packet to be ready for send out. The buffer sent as
+ argument must include the data to be sent and it must not be encrypted.
+ The packet also must have enough free space so that the SILC header
+ and padding maybe added to the packet. The packet is encrypted after
+ this function has returned.
- The destination buffer sent as argument must be initialized before
- calling this function, and, the data section and the start of the tail
- section must be same. Ie. we add the read data to the tail section of
- the buffer hence the data section is the start of the buffer.
+ The buffer sent as argument should be something like following:
- This returns amount of bytes read or -1 on error or -2 on case where
- all of the data could not be read at once. */
+ --------------------------------------------
+ | head | data | tail |
+ --------------------------------------------
+ ^ ^
+ 58 bytes x bytes
-int silc_packet_read(int sock, SilcBuffer dest)
+ So that the SILC header and 1 - 16 bytes of padding can fit to
+ the buffer. After assembly the buffer might look like this:
+
+ --------------------------------------------
+ | data | |
+ --------------------------------------------
+ ^ ^
+ Start of assembled packet
+
+ Packet construct is as follows:
+
+ n bytes SILC Header
+ 2 bytes Payload length
+ 1 byte Flags
+ 1 byte Packet type
+ 1 byte Padding length
+ 1 byte RESERVED
+ 1 bytes Source ID Length
+ 1 bytes Destination ID Length
+ 1 byte Source ID Type
+ n bytes Source ID
+ 1 byte Destination ID Type
+ n bytes Destination ID
+
+ 1 - 16 bytes Padding
+
+ n bytes Data payload
+
+ All fields in the packet will be authenticated by MAC. The MAC is
+ not computed here, it must be computed separately before encrypting
+ the packet.
+
+*/
+
+void silc_packet_assemble(SilcPacketContext *ctx, SilcCipher cipher)
{
- int len = 0;
- unsigned char buf[SILC_PACKET_READ_SIZE];
+ unsigned char tmppad[SILC_PACKET_MAX_PADLEN];
+ int block_len = cipher ? silc_cipher_get_block_len(cipher) : 0;
+ int i;
- SILC_LOG_DEBUG(("Reading data from socket %d", sock));
+ SILC_LOG_DEBUG(("Assembling outgoing packet"));
+
+ /* Get the true length of the packet. This is saved as payload length
+ into the packet header. This does not include the length of the
+ padding. */
+ if (!ctx->truelen)
+ ctx->truelen = ctx->buffer->len + SILC_PACKET_HEADER_LEN +
+ ctx->src_id_len + ctx->dst_id_len;
- /* Read the data from the socket. */
- len = read(sock, buf, sizeof(buf));
- if (len < 0) {
- if (errno == EAGAIN) {
- SILC_LOG_DEBUG(("Could not read immediately, will do it later"));
- return -2;
+ /* Calculate the length of the padding. The padding is calculated from
+ the data that will be encrypted. */
+ if (!ctx->padlen) {
+ if (ctx->long_pad)
+ ctx->padlen = SILC_PACKET_PADLEN_MAX(ctx->truelen);
+ else
+ ctx->padlen = SILC_PACKET_PADLEN(ctx->truelen, block_len);
+ }
+
+ /* Put the start of the data section to the right place. */
+ silc_buffer_push(ctx->buffer, SILC_PACKET_HEADER_LEN +
+ ctx->src_id_len + ctx->dst_id_len + ctx->padlen);
+
+ /* Get random padding */
+#if 1
+ for (i = 0; i < ctx->padlen; i++) tmppad[i] =
+ silc_rng_global_get_byte_fast();
+#else
+ /* XXX: For testing - to be removed */
+ memset(tmppad, 65, sizeof(tmppad));
+#endif
+
+ /* Create the packet. This creates the SILC header and adds padding,
+ rest of the buffer remains as it is. */
+ silc_buffer_format(ctx->buffer,
+ SILC_STR_UI_SHORT(ctx->truelen),
+ SILC_STR_UI_CHAR(ctx->flags),
+ SILC_STR_UI_CHAR(ctx->type),
+ SILC_STR_UI_CHAR(ctx->padlen),
+ SILC_STR_UI_CHAR(0),
+ SILC_STR_UI_CHAR(ctx->src_id_len),
+ SILC_STR_UI_CHAR(ctx->dst_id_len),
+ SILC_STR_UI_CHAR(ctx->src_id_type),
+ SILC_STR_UI_XNSTRING(ctx->src_id, ctx->src_id_len),
+ SILC_STR_UI_CHAR(ctx->dst_id_type),
+ SILC_STR_UI_XNSTRING(ctx->dst_id, ctx->dst_id_len),
+ SILC_STR_UI_XNSTRING(tmppad, ctx->padlen),
+ SILC_STR_END);
+
+ SILC_LOG_HEXDUMP(("Assembled packet, len %d", ctx->buffer->len),
+ ctx->buffer->data, ctx->buffer->len);
+
+ SILC_LOG_DEBUG(("Outgoing packet assembled"));
+}
+
+/* Prepare outgoing data buffer for packet sending. This moves the data
+ area so that new packet may be added into it. If needed this allocates
+ more space to the buffer. This handles directly the connection's
+ outgoing buffer in SilcSocketConnection object. */
+
+void silc_packet_send_prepare(SilcSocketConnection sock,
+ SilcUInt32 header_len,
+ SilcUInt32 padlen,
+ SilcUInt32 data_len)
+{
+ int totlen, oldlen;
+
+ totlen = header_len + padlen + data_len;
+
+ /* Prepare the outgoing buffer for packet sending. */
+ if (!sock->outbuf) {
+ /* Allocate new buffer. This is done only once per connection. */
+ SILC_LOG_DEBUG(("Allocating outgoing data buffer"));
+
+ if (totlen > SILC_PACKET_DEFAULT_SIZE)
+ sock->outbuf = silc_buffer_alloc(totlen);
+ else
+ sock->outbuf = silc_buffer_alloc(SILC_PACKET_DEFAULT_SIZE);
+ silc_buffer_pull_tail(sock->outbuf, totlen);
+ silc_buffer_pull(sock->outbuf, header_len + padlen);
+ } else {
+ if (SILC_IS_OUTBUF_PENDING(sock)) {
+ /* There is some pending data in the buffer. */
+
+ /* Allocate more space if needed */
+ if ((sock->outbuf->end - sock->outbuf->tail) <
+ (totlen + 20)) {
+ SILC_LOG_DEBUG(("Reallocating outgoing data buffer"));
+ sock->outbuf = silc_buffer_realloc(sock->outbuf,
+ sock->outbuf->truelen +
+ (totlen * 2));
+ }
+
+ oldlen = sock->outbuf->len;
+ silc_buffer_pull_tail(sock->outbuf, totlen);
+ silc_buffer_pull(sock->outbuf, header_len + padlen + oldlen);
+ } else {
+ /* Buffer is free for use */
+ silc_buffer_clear(sock->outbuf);
+
+ /* Allocate more space if needed */
+ if ((sock->outbuf->end - sock->outbuf->tail) < (totlen + 20)) {
+ SILC_LOG_DEBUG(("Reallocating outgoing data buffer"));
+ sock->outbuf = silc_buffer_realloc(sock->outbuf,
+ sock->outbuf->truelen +
+ (totlen * 2));
+ }
+
+ silc_buffer_pull_tail(sock->outbuf, totlen);
+ silc_buffer_pull(sock->outbuf, header_len + padlen);
}
- SILC_LOG_ERROR(("Cannot read from socket: %d", strerror(errno)));
- return -1;
}
+}
- if (!len)
- return 0;
+/******************************************************************************
+
+ Packet Reception Routines
+
+******************************************************************************/
+
+static int silc_packet_decrypt(SilcCipher cipher, SilcHmac hmac,
+ SilcUInt32 sequence, SilcBuffer buffer,
+ bool normal);
+
+/* Receives packet from network and reads the data into connection's
+ incoming data buffer. If the data was read directly this returns the
+ read bytes, if error occured this returns -1, if the data could not
+ be read directly at this time this returns -2 in which case the data
+ should be read again at some later time, or If EOF occured this returns
+ 0. */
+
+int silc_packet_receive(SilcSocketConnection sock)
+{
+ int ret;
+
+ SILC_LOG_DEBUG(("Receiving packet from %s:%d [%s]", sock->hostname,
+ sock->port,
+ (sock->type == SILC_SOCKET_TYPE_UNKNOWN ? "Unknown" :
+ sock->type == SILC_SOCKET_TYPE_CLIENT ? "Client" :
+ sock->type == SILC_SOCKET_TYPE_SERVER ? "Server" :
+ "Router")));
+
+ /* Read some data from connection */
+ ret = silc_socket_read(sock);
+
+ return ret;
+}
+
+/* Processes and decrypts the incmoing data, and calls parser callback
+ for each received packet that will handle the actual packet parsing.
+ If more than one packet was received this calls the parser multiple
+ times. The parser callback will get context SilcPacketParserContext
+ that includes the packet and the `parser_context' sent to this
+ function.
+
+ The `local_is_router' indicates whether the caller is router server
+ in which case the receiving process of a certain packet types may
+ be special. Normal server and client must set it to FALSE. The
+ SilcPacketParserContext will indicate also whether the received
+ packet was normal or special packet. */
+
+bool silc_packet_receive_process(SilcSocketConnection sock,
+ bool local_is_router,
+ SilcCipher cipher, SilcHmac hmac,
+ SilcUInt32 sequence,
+ SilcPacketParserCallback parser,
+ void *parser_context)
+{
+ SilcPacketParserContext *parse_ctx;
+ int packetlen, paddedlen, mac_len = 0;
+ bool cont = TRUE;
+
+ /* Do not process for disconnected connection */
+ if (SILC_IS_DISCONNECTED(sock))
+ return TRUE;
+
+ if (sock->inbuf->len < SILC_PACKET_MIN_HEADER_LEN)
+ return TRUE;
+
+ if (hmac)
+ mac_len = silc_hmac_len(hmac);
+
+ /* Parse the packets from the data */
+ while (sock->inbuf->len > 0 && cont) {
+
+ if (sock->inbuf->len < SILC_PACKET_MIN_HEADER_LEN) {
+ SILC_LOG_DEBUG(("Partial packet in queue, waiting for the rest"));
+ return TRUE;
+ }
+
+ /* Decrypt first 16 bytes of the packet */
+ if (!SILC_IS_INBUF_PENDING(sock) && cipher)
+ silc_cipher_decrypt(cipher, sock->inbuf->data, sock->inbuf->data,
+ SILC_PACKET_MIN_HEADER_LEN, cipher->iv);
+
+ /* Get packet lenght and full packet length with padding */
+ SILC_PACKET_LENGTH(sock->inbuf, packetlen, paddedlen);
+
+ /* Sanity checks */
+ if (packetlen < SILC_PACKET_MIN_LEN) {
+ SILC_LOG_DEBUG(("Received invalid packet, dropped"));
+ silc_buffer_clear(sock->inbuf);
+ return FALSE;
+ }
+
+ if (sock->inbuf->len < paddedlen + mac_len) {
+ SILC_LOG_DEBUG(("Received partial packet, waiting for the rest"
+ "(%d < %d)", sock->inbuf->len, paddedlen + mac_len));
+ SILC_SET_INBUF_PENDING(sock);
+ return TRUE;
+ }
- /* Insert the data to the buffer. If the data doesn't fit to the
- buffer space is allocated for the buffer.
- XXX: I don't like this. -Pekka */
- if (dest) {
-
- /* If the data doesn't fit we just have to allocate a whole new
- data area */
- if (dest->truelen <= len) {
-
- /* Free the old buffer */
- memset(dest->head, 'F', dest->truelen);
- silc_free(dest->head);
-
- /* Allocate new data area */
- len += SILC_PACKET_DEFAULT_SIZE;
- dest->data = silc_calloc(len, sizeof(char));
- dest->truelen = len;
- dest->len = 0;
- dest->head = dest->data;
- dest->data = dest->data;
- dest->tail = dest->data;
- dest->end = dest->data + dest->truelen;
- len -= SILC_PACKET_DEFAULT_SIZE;
+ SILC_UNSET_INBUF_PENDING(sock);
+ parse_ctx = silc_calloc(1, sizeof(*parse_ctx));
+ parse_ctx->packet = silc_packet_context_alloc();
+ parse_ctx->packet->buffer = silc_buffer_alloc(paddedlen + mac_len);
+ parse_ctx->packet->type = sock->inbuf->data[3];
+ parse_ctx->packet->padlen = sock->inbuf->data[4];
+ parse_ctx->packet->sequence = sequence++;
+ parse_ctx->sock = sock;
+ parse_ctx->context = parser_context;
+
+ silc_buffer_pull_tail(parse_ctx->packet->buffer,
+ SILC_BUFFER_END(parse_ctx->packet->buffer));
+ silc_buffer_put(parse_ctx->packet->buffer, sock->inbuf->data,
+ paddedlen + mac_len);
+
+ SILC_LOG_HEXDUMP(("Incoming packet (%d) (%dB decrypted), len %d",
+ sequence - 1, SILC_PACKET_MIN_HEADER_LEN,
+ paddedlen + mac_len),
+ sock->inbuf->data, paddedlen + mac_len);
+
+ /* Check whether this is normal or special packet */
+ if (local_is_router) {
+ if (sock->inbuf->data[3] == SILC_PACKET_PRIVATE_MESSAGE &&
+ (sock->inbuf->data[2] & SILC_PACKET_FLAG_PRIVMSG_KEY))
+ parse_ctx->normal = FALSE;
+ else if (sock->inbuf->data[3] != SILC_PACKET_CHANNEL_MESSAGE ||
+ (sock->inbuf->data[3] == SILC_PACKET_CHANNEL_MESSAGE &&
+ sock->type == SILC_SOCKET_TYPE_ROUTER))
+ parse_ctx->normal = TRUE;
+ } else {
+ if (sock->inbuf->data[3] == SILC_PACKET_PRIVATE_MESSAGE &&
+ (sock->inbuf->data[2] & SILC_PACKET_FLAG_PRIVMSG_KEY))
+ parse_ctx->normal = FALSE;
+ else if (sock->inbuf->data[3] != SILC_PACKET_CHANNEL_MESSAGE)
+ parse_ctx->normal = TRUE;
}
- silc_buffer_put_tail(dest, buf, len);
- silc_buffer_pull_tail(dest, len);
+ /* Decrypt rest of the packet */
+ if (cipher)
+ if (silc_packet_decrypt(cipher, hmac, parse_ctx->packet->sequence,
+ parse_ctx->packet->buffer,
+ parse_ctx->normal) == -1) {
+ SILC_LOG_WARNING(("Packet decryption failed %s:%d [%s]",
+ sock->hostname, sock->port,
+ (sock->type == SILC_SOCKET_TYPE_UNKNOWN ? "Unknown" :
+ sock->type == SILC_SOCKET_TYPE_CLIENT ? "Client" :
+ sock->type == SILC_SOCKET_TYPE_SERVER ? "Server" :
+ "Router")));
+ }
+
+ /* Pull the packet from inbuf thus we'll get the next one
+ in the inbuf. */
+ silc_buffer_pull(sock->inbuf, paddedlen + mac_len);
+
+ /* Call the parser */
+ cont = (*parser)(parse_ctx, parser_context);
}
- SILC_LOG_DEBUG(("Read %d bytes", len));
+ if (cont == FALSE && sock->inbuf->len > 0)
+ return TRUE;
+
+ SILC_LOG_DEBUG(("Clearing inbound buffer"));
+ silc_buffer_clear(sock->inbuf);
+ return TRUE;
+}
+
+/* Checks MAC in the packet. Returns TRUE if MAC is Ok. This is called
+ after packet has been totally decrypted and parsed. */
- return len;
+static int silc_packet_check_mac(SilcHmac hmac, SilcBuffer buffer,
+ SilcUInt32 sequence)
+{
+ /* Check MAC */
+ if (hmac) {
+ unsigned char mac[32], psn[4];
+ SilcUInt32 mac_len;
+
+ SILC_LOG_DEBUG(("Verifying MAC"));
+
+ /* Compute HMAC of packet */
+
+ memset(mac, 0, sizeof(mac));
+ silc_hmac_init(hmac);
+ SILC_PUT32_MSB(sequence, psn);
+ silc_hmac_update(hmac, psn, 4);
+ silc_hmac_update(hmac, buffer->data, buffer->len);
+ silc_hmac_final(hmac, mac, &mac_len);
+
+ /* Compare the HMAC's (buffer->tail has the packet's HMAC) */
+ if (memcmp(buffer->tail, mac, mac_len)) {
+ SILC_LOG_ERROR(("MAC failed"));
+ return FALSE;
+ }
+
+ SILC_LOG_DEBUG(("MAC is Ok"));
+ memset(mac, 0, sizeof(mac));
+ }
+
+ return TRUE;
}
-/* Encrypts a packet. */
+/* Decrypts rest of the packet (after decrypting just the SILC header).
+ After calling this function the packet is ready to be parsed by calling
+ silc_packet_parse. If everything goes without errors this returns TRUE,
+ if packet is malformed this returns FALSE. */
-void silc_packet_encrypt(SilcCipher cipher, SilcBuffer buffer,
- unsigned int len)
+static int silc_packet_decrypt_rest(SilcCipher cipher, SilcHmac hmac,
+ SilcBuffer buffer)
{
- SILC_LOG_DEBUG(("Encrypting packet, cipher %s, len %d (%d)",
- cipher->cipher->name, len, len - 2));
+ if (cipher) {
+
+ /* Pull MAC from packet before decryption */
+ if (hmac) {
+ if ((buffer->len - silc_hmac_len(hmac)) > SILC_PACKET_MIN_LEN) {
+ silc_buffer_push_tail(buffer, silc_hmac_len(hmac));
+ } else {
+ SILC_LOG_DEBUG(("Bad MAC length in packet, packet dropped"));
+ return FALSE;
+ }
+ }
+
+ SILC_LOG_DEBUG(("Decrypting rest of the packet"));
- /* Encrypt the data area of the packet. 3 bytes of the packet
- are not encrypted. */
- cipher->cipher->encrypt(cipher->context, buffer->data + 2,
- buffer->data + 2, len - 2, cipher->iv);
+ /* Decrypt rest of the packet */
+ silc_buffer_pull(buffer, SILC_PACKET_MIN_HEADER_LEN);
+ silc_cipher_decrypt(cipher, buffer->data, buffer->data, buffer->len,
+ cipher->iv);
+ silc_buffer_push(buffer, SILC_PACKET_MIN_HEADER_LEN);
+ SILC_LOG_HEXDUMP(("Fully decrypted packet, len %d", buffer->len),
+ buffer->data, buffer->len);
+ }
+
+ return TRUE;
}
-/* Decrypts a packet. */
+/* Decrypts rest of the SILC Packet header that has been decrypted partly
+ already. This decrypts the padding of the packet also. After calling
+ this function the packet is ready to be parsed by calling function
+ silc_packet_parse. This is used in special packet reception (protocol
+ defines the way of decrypting special packets). */
+
+static int silc_packet_decrypt_rest_special(SilcCipher cipher,
+ SilcHmac hmac,
+ SilcBuffer buffer)
+{
+ /* Decrypt rest of the header plus padding */
+ if (cipher) {
+ SilcUInt16 len;
+
+ /* Pull MAC from packet before decryption */
+ if (hmac) {
+ if ((buffer->len - silc_hmac_len(hmac)) > SILC_PACKET_MIN_LEN) {
+ silc_buffer_push_tail(buffer, silc_hmac_len(hmac));
+ } else {
+ SILC_LOG_DEBUG(("Bad MAC length in packet, packet dropped"));
+ return FALSE;
+ }
+ }
+
+ SILC_LOG_DEBUG(("Decrypting rest of the header"));
+
+ /* padding length + src id len + dst id len + header length - 16
+ bytes already decrypted, gives the rest of the encrypted packet */
+ len = (((SilcUInt8)buffer->data[4] + (SilcUInt8)buffer->data[6] +
+ (SilcUInt8)buffer->data[7] + SILC_PACKET_HEADER_LEN) -
+ SILC_PACKET_MIN_HEADER_LEN);
+
+ silc_buffer_pull(buffer, SILC_PACKET_MIN_HEADER_LEN);
+ if (len > buffer->len) {
+ SILC_LOG_DEBUG(("Garbage in header of packet, bad packet length, "
+ "packet dropped"));
+ return FALSE;
+ }
+ silc_cipher_decrypt(cipher, buffer->data, buffer->data, len, cipher->iv);
+ silc_buffer_push(buffer, SILC_PACKET_MIN_HEADER_LEN);
+ SILC_LOG_HEXDUMP(("packet, len %d", buffer->len),
+ buffer->data, buffer->len);
+ }
+
+ return TRUE;
+}
-void silc_packet_decrypt(SilcCipher cipher, SilcBuffer buffer,
- unsigned int len)
+/* Decrypts a packet. This assumes that typical SILC packet is the
+ packet to be decrypted and thus checks for normal and special SILC
+ packets and can handle both of them. This also computes and checks
+ the HMAC of the packet. If any other special or customized decryption
+ processing is required this function cannot be used. This returns
+ -1 on error, 0 when packet is normal packet and 1 when the packet
+ is special and requires special processing.
+
+ The `check_packet' is a callback funtion that this function will
+ call. The callback relates to the checking whether the packet is
+ normal packet or special packet and how it should be processed. If
+ the callback return TRUE the packet is normal and FALSE if the packet
+ is special and requires special procesing. */
+
+static int silc_packet_decrypt(SilcCipher cipher, SilcHmac hmac,
+ SilcUInt32 sequence, SilcBuffer buffer,
+ bool normal)
{
- SILC_LOG_DEBUG(("Decrypting packet, cipher %s, len %d (%d)",
- cipher->cipher->name, len, len - 2));
+ /* If the packet type is not any special type lets decrypt rest
+ of the packet here. */
+ if (normal == TRUE) {
+ /* Normal packet, decrypt rest of the packet */
+ if (!silc_packet_decrypt_rest(cipher, hmac, buffer))
+ return -1;
- /* Decrypt the data area of the packet. 2 bytes of the packet
- are not decrypted (they are not encrypted). */
- cipher->cipher->decrypt(cipher->context, buffer->data + 2,
- buffer->data + 2, len - 2, cipher->iv);
+ /* Check MAC */
+ if (!silc_packet_check_mac(hmac, buffer, sequence))
+ return -1;
+
+ return 0;
+ } else {
+ /* Packet requires special handling, decrypt rest of the header.
+ This only decrypts. */
+ if (!silc_packet_decrypt_rest_special(cipher, hmac, buffer))
+ return -1;
+ /* Check MAC */
+ if (!silc_packet_check_mac(hmac, buffer, sequence))
+ return -1;
+
+ return 1;
+ }
}
/* Parses the packet. This is called when a whole packet is ready to be
function returns the type of the packet. The data section of the
buffer is parsed, not head or tail sections. */
-SilcPacketType silc_packet_parse(SilcPacketContext *ctx)
+SilcPacketType silc_packet_parse(SilcPacketContext *ctx, SilcCipher cipher)
{
SilcBuffer buffer = ctx->buffer;
- int len;
+ SilcUInt8 tmp;
+ int len, ret;
SILC_LOG_DEBUG(("Parsing incoming packet"));
SILC_STR_UI_SHORT(&ctx->truelen),
SILC_STR_UI_CHAR(&ctx->flags),
SILC_STR_UI_CHAR(&ctx->type),
- SILC_STR_UI_SHORT(&ctx->src_id_len),
- SILC_STR_UI_SHORT(&ctx->dst_id_len),
+ SILC_STR_UI_CHAR(&ctx->padlen),
+ SILC_STR_UI_CHAR(&tmp),
+ SILC_STR_UI_CHAR(&ctx->src_id_len),
+ SILC_STR_UI_CHAR(&ctx->dst_id_len),
SILC_STR_UI_CHAR(&ctx->src_id_type),
SILC_STR_END);
+ if (len == -1 || tmp != 0)
+ return SILC_PACKET_NONE;
if (ctx->src_id_len > SILC_PACKET_MAX_ID_LEN ||
ctx->dst_id_len > SILC_PACKET_MAX_ID_LEN) {
- SILC_LOG_ERROR(("Bad ID lengths in packet"));
+ SILC_LOG_ERROR(("Bad ID lengths in packet (%d and %d)",
+ ctx->src_id_len, ctx->dst_id_len));
return SILC_PACKET_NONE;
}
- /* Calculate length of padding in packet */
- ctx->padlen = SILC_PACKET_PADLEN(ctx->truelen);
-
silc_buffer_pull(buffer, len);
- silc_buffer_unformat(buffer,
- SILC_STR_UI_XNSTRING_ALLOC(&ctx->src_id,
- ctx->src_id_len),
- SILC_STR_UI_CHAR(&ctx->dst_id_type),
- SILC_STR_UI_XNSTRING_ALLOC(&ctx->dst_id,
- ctx->dst_id_len),
- SILC_STR_UI_XNSTRING(NULL, ctx->padlen),
- SILC_STR_END);
+ ret = silc_buffer_unformat(buffer,
+ SILC_STR_UI_XNSTRING_ALLOC(&ctx->src_id,
+ ctx->src_id_len),
+ SILC_STR_UI_CHAR(&ctx->dst_id_type),
+ SILC_STR_UI_XNSTRING_ALLOC(&ctx->dst_id,
+ ctx->dst_id_len),
+ SILC_STR_UI_XNSTRING(NULL, ctx->padlen),
+ SILC_STR_END);
+ if (ret == -1)
+ return SILC_PACKET_NONE;
+
silc_buffer_push(buffer, len);
SILC_LOG_HEXDUMP(("parsed packet, len %d", ctx->buffer->len),
the header in a way that it does not take the data area into account
and parses the header and padding area only. */
-SilcPacketType silc_packet_parse_special(SilcPacketContext *ctx)
+SilcPacketType silc_packet_parse_special(SilcPacketContext *ctx,
+ SilcCipher cipher)
{
SilcBuffer buffer = ctx->buffer;
- int len, tmplen;
+ SilcUInt8 tmp;
+ int len, ret;
SILC_LOG_DEBUG(("Parsing incoming packet"));
SILC_STR_UI_SHORT(&ctx->truelen),
SILC_STR_UI_CHAR(&ctx->flags),
SILC_STR_UI_CHAR(&ctx->type),
- SILC_STR_UI_SHORT(&ctx->src_id_len),
- SILC_STR_UI_SHORT(&ctx->dst_id_len),
+ SILC_STR_UI_CHAR(&ctx->padlen),
+ SILC_STR_UI_CHAR(&tmp),
+ SILC_STR_UI_CHAR(&ctx->src_id_len),
+ SILC_STR_UI_CHAR(&ctx->dst_id_len),
SILC_STR_UI_CHAR(&ctx->src_id_type),
SILC_STR_END);
+ if (len == -1 || tmp != 0) {
+ SILC_LOG_ERROR(("Malformed packet header, packet dropped"));
+ return SILC_PACKET_NONE;
+ }
if (ctx->src_id_len > SILC_PACKET_MAX_ID_LEN ||
ctx->dst_id_len > SILC_PACKET_MAX_ID_LEN) {
- SILC_LOG_ERROR(("Bad ID lengths in packet"));
+ SILC_LOG_ERROR(("Bad ID lengths in packet (%d and %d)",
+ ctx->src_id_len, ctx->dst_id_len));
return SILC_PACKET_NONE;
}
- /* Calculate length of padding in packet. As this is special packet
- the data area is not used in the padding calculation as it won't
- be decrypted by the caller. */
- tmplen = SILC_PACKET_HEADER_LEN + ctx->src_id_len + ctx->dst_id_len;
- ctx->padlen = SILC_PACKET_PADLEN(tmplen);
-
silc_buffer_pull(buffer, len);
- silc_buffer_unformat(buffer,
- SILC_STR_UI_XNSTRING_ALLOC(&ctx->src_id,
- ctx->src_id_len),
- SILC_STR_UI_CHAR(&ctx->dst_id_type),
- SILC_STR_UI_XNSTRING_ALLOC(&ctx->dst_id,
- ctx->dst_id_len),
- SILC_STR_UI_XNSTRING(NULL, ctx->padlen),
- SILC_STR_END);
+ ret = silc_buffer_unformat(buffer,
+ SILC_STR_UI_XNSTRING_ALLOC(&ctx->src_id,
+ ctx->src_id_len),
+ SILC_STR_UI_CHAR(&ctx->dst_id_type),
+ SILC_STR_UI_XNSTRING_ALLOC(&ctx->dst_id,
+ ctx->dst_id_len),
+ SILC_STR_UI_XNSTRING(NULL, ctx->padlen),
+ SILC_STR_END);
+ if (ret == -1) {
+ SILC_LOG_ERROR(("Malformed packet header, packet dropped"));
+ return SILC_PACKET_NONE;
+ }
+
silc_buffer_push(buffer, len);
SILC_LOG_HEXDUMP(("parsed packet, len %d", ctx->buffer->len),
return ctx->type;
}
-/* Assembles a new packet to be ready for send out. The buffer sent as
- argument must include the data to be sent and it must not be encrypted.
- The packet also must have enough free space so that the SILC header
- and padding maybe added to the packet. The packet is encrypted after
- this function has returned.
-
- The buffer sent as argument should be something like following:
-
- --------------------------------------------
- | head | data | tail |
- --------------------------------------------
- ^ ^
- 58 bytes x bytes
-
- So that the SILC header and 1 - 16 bytes of padding can fit to
- the buffer. After assembly the buffer might look like this:
+/* Allocate packet context */
- --------------------------------------------
- | data | |
- --------------------------------------------
- ^ ^
- Start of assembled packet
-
- Packet construct is as follows (* = won't be encrypted):
-
- x bytes SILC Header
- 2 bytes Payload length (*)
- 1 byte Flags (*)
- 1 byte Packet type
- 1 byte Source ID Type
- 2 bytes Source ID Length
- x bytes Source ID
- 1 byte Destination ID Type
- 2 bytes Destination ID Length
- x bytes Destination ID
-
- 1 - 16 bytes Padding
-
- x bytes Data payload
-
- All fields in the packet will be authenticated by MAC. The MAC is
- not computed here, it must be computed differently before encrypting
- the packet.
-
-*/
-
-void silc_packet_assemble(SilcPacketContext *ctx)
+SilcPacketContext *silc_packet_context_alloc(void)
{
- unsigned char tmppad[SILC_PACKET_MAX_PADLEN];
- int i;
-
- SILC_LOG_DEBUG(("Assembling outgoing packet"));
-
- /* Get the true length of the packet. This is saved as payload length
- into the packet header. This does not include the length of the
- padding. */
- if (!ctx->truelen)
- ctx->truelen = ctx->buffer->len + SILC_PACKET_HEADER_LEN +
- ctx->src_id_len + ctx->dst_id_len;
-
- /* Calculate the length of the padding. The padding is calculated from
- the data that will be encrypted. As protocol states 3 first bytes
- of the packet are not encrypted they are not included in the
- padding calculation. */
- if (!ctx->padlen)
- ctx->padlen = SILC_PACKET_PADLEN(ctx->truelen);
-
- /* Put the start of the data section to the right place. */
- silc_buffer_push(ctx->buffer, SILC_PACKET_HEADER_LEN +
- ctx->src_id_len + ctx->dst_id_len + ctx->padlen);
+ SilcPacketContext *ctx = silc_calloc(1, sizeof(*ctx));
+ ctx->users++;
+ return ctx;
+}
- /* Get random padding */
-#if 1
- for (i = 0; i < ctx->padlen; i++)
- tmppad[i] = silc_rng_get_byte(ctx->rng);
-#else
- /* XXX: For testing - to be removed */
- memset(tmppad, 65, sizeof(tmppad));
-#endif
+/* Increse the reference count of the packet context. */
- /* Create the packet. This creates the SILC header and adds padding,
- rest of the buffer remains as it is. */
- silc_buffer_format(ctx->buffer,
- SILC_STR_UI_SHORT(ctx->truelen),
- SILC_STR_UI_CHAR(ctx->flags),
- SILC_STR_UI_CHAR(ctx->type),
- SILC_STR_UI_SHORT(ctx->src_id_len),
- SILC_STR_UI_SHORT(ctx->dst_id_len),
- SILC_STR_UI_CHAR(ctx->src_id_type),
- SILC_STR_UI_XNSTRING(ctx->src_id, ctx->src_id_len),
- SILC_STR_UI_CHAR(ctx->dst_id_type),
- SILC_STR_UI_XNSTRING(ctx->dst_id, ctx->dst_id_len),
- SILC_STR_UI_XNSTRING(tmppad, ctx->padlen),
- SILC_STR_END);
+SilcPacketContext *silc_packet_context_dup(SilcPacketContext *ctx)
+{
+ ctx->users++;
+ SILC_LOG_DEBUG(("Packet context %p refcnt %d->%d", ctx, ctx->users - 1,
+ ctx->users));
+ return ctx;
+}
- SILC_LOG_HEXDUMP(("Assembled packet, len %d", ctx->buffer->len),
- ctx->buffer->data, ctx->buffer->len);
+/* Decrese the reference count of the packet context and free it only if
+ it is zero. */
- SILC_LOG_DEBUG(("Outgoing packet assembled"));
+void silc_packet_context_free(SilcPacketContext *ctx)
+{
+ ctx->users--;
+ SILC_LOG_DEBUG(("Packet context %p refcnt %d->%d", ctx, ctx->users + 1,
+ ctx->users));
+ if (ctx->users < 1)
+ {
+ if (ctx->buffer)
+ silc_buffer_free(ctx->buffer);
+ if (ctx->src_id)
+ silc_free(ctx->src_id);
+ if (ctx->dst_id)
+ silc_free(ctx->dst_id);
+ silc_free(ctx);
+ }
}
projects / silc.git / blobdiff