1 /****h* silccore/silcpacket.h
9 * Author: Pekka Riikonen <priikone@poseidon.pspt.fi>
11 * Copyright (C) 1997 - 2001 Pekka Riikonen
13 * This program is free software; you can redistribute it and/or modify
14 * it under the terms of the GNU General Public License as published by
15 * the Free Software Foundation; either version 2 of the License, or
16 * (at your option) any later version.
18 * This program is distributed in the hope that it will be useful,
19 * but WITHOUT ANY WARRANTY; without even the implied warranty of
20 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
21 * GNU General Public License for more details.
25 * Implementation of the packet routines for sending and receiving
26 * SILC Packets. These includes the data sending routines and data
27 * reading routines, encrypting and decrypting routines, packet assembling
28 * and packet parsing routines.
35 /* Default byte size of the packet. */
36 #define SILC_PACKET_DEFAULT_SIZE SILC_SOCKET_BUF_SIZE
38 /* Header length without source and destination ID's. */
39 #define SILC_PACKET_HEADER_LEN 8 + 2
41 /* Minimum length of SILC Packet Header. This much is decrypted always
42 when packet is received to be able to get all the relevant data out
44 #define SILC_PACKET_MIN_HEADER_LEN 16 + 2
46 /* Maximum padding length */
47 #define SILC_PACKET_MAX_PADLEN 16
49 /* Minimum packet length */
50 #define SILC_PACKET_MIN_LEN (SILC_PACKET_HEADER_LEN + 1)
52 /* Maximum length of ID */
53 #define SILC_PACKET_MAX_ID_LEN 16
55 /****d* silccore/SilcPacketAPI/SilcPacketType
59 * typedef unsigned char SilcPacketType;
63 * SILC packet type definition and all the packet types.
67 typedef unsigned char SilcPacketType;
69 /* SILC Packet types. */
70 #define SILC_PACKET_NONE 0 /* NULL, never sent */
71 #define SILC_PACKET_DISCONNECT 1 /* Disconnection */
72 #define SILC_PACKET_SUCCESS 2 /* Success */
73 #define SILC_PACKET_FAILURE 3 /* Failure */
74 #define SILC_PACKET_REJECT 4 /* Rejected */
75 #define SILC_PACKET_NOTIFY 5 /* Notify message */
76 #define SILC_PACKET_ERROR 6 /* Error message */
77 #define SILC_PACKET_CHANNEL_MESSAGE 7 /* Message for channel */
78 #define SILC_PACKET_CHANNEL_KEY 8 /* Key of the channel */
79 #define SILC_PACKET_PRIVATE_MESSAGE 9 /* Private message */
80 #define SILC_PACKET_PRIVATE_MESSAGE_KEY 10 /* Private message key*/
81 #define SILC_PACKET_COMMAND 11 /* Command */
82 #define SILC_PACKET_COMMAND_REPLY 12 /* Reply to a command */
83 #define SILC_PACKET_KEY_EXCHANGE 13 /* Start of KE */
84 #define SILC_PACKET_KEY_EXCHANGE_1 14 /* KE1 */
85 #define SILC_PACKET_KEY_EXCHANGE_2 15 /* KE2 */
86 #define SILC_PACKET_CONNECTION_AUTH_REQUEST 16 /* Request of auth meth */
87 #define SILC_PACKET_CONNECTION_AUTH 17 /* Connectinon auth */
88 #define SILC_PACKET_NEW_ID 18 /* Sending new ID */
89 #define SILC_PACKET_NEW_CLIENT 19 /* Client registering */
90 #define SILC_PACKET_NEW_SERVER 20 /* Server registering */
91 #define SILC_PACKET_NEW_CHANNEL 21 /* Channel registering */
92 #define SILC_PACKET_REKEY 22 /* Re-key start */
93 #define SILC_PACKET_REKEY_DONE 23 /* Re-key done */
94 #define SILC_PACKET_HEARTBEAT 24 /* Heartbeat */
95 #define SILC_PACKET_KEY_AGREEMENT 25 /* Key Agreement request */
96 #define SILC_PACKET_CELL_ROUTERS 26 /* Cell routers backup */
98 #define SILC_PACKET_PRIVATE 200 /* Private range start */
99 #define SILC_PACKET_MAX 255 /* RESERVED */
102 /****d* silccore/SilcPacketAPI/SilcPacketVersion
106 * typedef unsigned char SilcPacketVersion;
110 * SILC packet version type definition.
113 typedef unsigned char SilcPacketVersion;
115 /****d* silccore/SilcPacketAPI/SilcPacketFlags
119 * typedef unsigned char SilcPacketFlags;
123 * SILC packet flags type definition and all the packet flags.
127 typedef unsigned char SilcPacketFlags;
129 /* All defined packet flags */
130 #define SILC_PACKET_FLAG_NONE 0x00 /* No flags */
131 #define SILC_PACKET_FLAG_PRIVMSG_KEY 0x01 /* Private message key */
132 #define SILC_PACKET_FLAG_LIST 0x02 /* Packet is a list */
133 #define SILC_PACKET_FLAG_BROADCAST 0x04 /* Packet is a broadcast */
136 /* Rest of flags still available
137 #define SILC_PACKET_FLAG_XXX 0x08
138 #define SILC_PACKET_FLAG_XXX 0x10
139 #define SILC_PACKET_FLAG_XXX 0x20
140 #define SILC_PACKET_FLAG_XXX 0x40
141 #define SILC_PACKET_FLAG_XXX 0x80
144 /****s* silccore/SilcPacketAPI/SilcPacketContext
148 * typedef struct { ... } SilcPacketContext;
152 * In packet sending this is filled and sent to silc_packet_assemble
153 * which then uses it to assemble new packet. In packet reception pointer
154 * to this context is sent to silc_packet_parse which parses the packet
155 * and returns the relevant information to this structure. On packet
156 * reception returned ID's are always the hash values of the ID's from
159 * Short description of the fields following:
165 * SilcPacketType type
167 * Type of the packet. Types are defined below.
169 * SilcPacketFlags flags
171 * Packet flags. Flags are defined above.
173 * unsigned char *src_id
175 * unsigned char src_id_type
177 * Source ID, its length and type. On packet reception retuned ID's
178 * are always the hash values of the ID's from the packet.
180 * unsigned char *dst_id;
182 * unsigned char src_id_type;
184 * Destination ID, its length and type. On packet reception retuned
185 * ID's are always the hash values of the ID's from the packet.
190 * The true lenght of the packet and the padded length of the packet.
191 * These may be set by the caller before calling any of the
192 * silc_packet_* routines. If not provided the library will calculate
197 * Reference counter for this context. The context is freed only
198 * after the reference counter hits zero. The counter is added
199 * calling silc_packet_context_dup and decreased by calling the
200 * silc_packet_context_free.
206 SilcPacketFlags flags;
208 unsigned char *src_id;
210 unsigned char src_id_type;
212 unsigned char *dst_id;
214 unsigned char dst_id_type;
221 SilcSocketConnection sock;
226 /****s* silccore/SilcPacketAPI/SilcPacketParserContext
230 * typedef struct { ... } SilcPacketParserContext;
234 * This context is used in packet reception when silc_packet_receive_process
235 * function calls parser callback that performs the actual packet decryption
236 * and parsing. This context is sent as argument to the parser function.
237 * This context must be free'd by the parser callback function.
239 * Following description of the fields:
241 * SilcPacketContext *packet
243 * The actual packet received from the network. In this phase the
244 * context is not parsed, only the packet->buffer is allocated and
245 * it includes the raw packet data, which is encrypted.
247 * SilcSocketConnection sock
249 * The associated connection.
253 * User context that is sent to the silc_packet_receive_process
254 * function. This usually includes application and connection specific
259 SilcPacketContext *packet;
260 SilcSocketConnection sock;
262 } SilcPacketParserContext;
264 /****f* silccore/SilcPacketAPI/SilcPacketParserCallback
268 * typedef void (*SilcPacketParserCallback)(SilcPacketParserContext
273 * This callback is given to the silc_packet_receive_process function.
274 * The callback is called by the library every time a packet is
275 * received from the network. After the packet has been decrypted
276 * and at least partially parsed it is passed to the application
277 * for further parsing using this callback and the SilcPacketParserContext
278 * context. The application receiving the SilcPacketParserContext
282 typedef void (*SilcPacketParserCallback)(SilcPacketParserContext
285 /****f* silccore/SilcPacketAPI/SilcPacketCheckDecrypt
289 * typedef int (*SilcPacketCheckDecrypt)(SilcPacketType packet_type,
291 * SilcPacketContext *packet,
296 * This callback function relates to the checking whether the packet is
297 * normal packet or special packet and how it should be processed. If
298 * the callback returns TRUE the packet is normal and FALSE if the packet
299 * is special and requires special procesing. Some of the packets in
300 * SILC are special (like channel message packets that are encrypted
301 * using channel specific keys) and requires special processing. That
302 * is the reason for this callback function.
304 * The library will call this function if provided for the
305 * silc_packet_decrypt function. The `packet_type' is the type of
306 * packet received (this is also actually the first time application
307 * receives information of the received packet, next time it receives
308 * it is when the SilcPacketParserCallback function is called),
309 * the `buffer' is the raw packet data the `packet' the allocated
310 * SilcPacketContext that is filled when parsing the packet and `context'
311 * is application specific user context.
314 typedef int (*SilcPacketCheckDecrypt)(SilcPacketType packet_type,
316 SilcPacketContext *packet,
321 /****d* silccore/SilcPacketAPI/SILC_PACKET_LENGTH
325 * #define SILC_PACKET_LENGTH ...
329 * Returns true length of the packet and padded length of the packet.
330 * This is primarily used by the libary in packet parsing phase but
331 * the application may use it as well if needed.
335 #define SILC_PACKET_LENGTH(__packet, __ret_truelen, __ret_padlen) \
337 SILC_GET16_MSB((__ret_truelen), (__packet)->data); \
338 (__ret_padlen) = (((__ret_truelen) - 2) + \
339 SILC_PACKET_MAX_PADLEN) & ~(SILC_PACKET_MAX_PADLEN - 1); \
343 /****d* silccore/SilcPacketAPI/SILC_PACKET_PADLEN
347 * #define SILC_PACKET_PADLEN ...
351 * Returns the length of the padding in the packet. This is used
352 * by various library routines to determine needed padding length.
356 #define SILC_PACKET_PADLEN(__packetlen) \
357 SILC_PACKET_MAX_PADLEN - ((__packetlen) - 2) % SILC_PACKET_MAX_PADLEN;
362 /****f* silccore/SilcPacketAPI/silc_packet_write
366 * int silc_packet_write(int sock, SilcBuffer src);
370 * Writes data from encrypted buffer to the socket connection. If the
371 * data cannot be written at once, it will be written later with a timeout.
372 * The data is written from the data section of the buffer, not from head
373 * or tail section. This automatically pulls the data section towards end
374 * after writing the data.
377 int silc_packet_write(int sock, SilcBuffer src);
379 /****f* silccore/SilcPacketAPI/silc_packet_send
383 * int silc_packet_send(SilcSocketConnection sock, int force_send);
387 * Actually sends the packet. This flushes the connections outgoing data
388 * buffer. If data is sent directly to the network this returns the bytes
389 * written, if error occured this returns -1 and if the data could not
390 * be written directly to the network at this time this returns -2, in
391 * which case the data should be queued by the caller and sent at some
392 * later time. If `force_send' is TRUE this attempts to write the data
393 * directly to the network, if FALSE, this returns -2.
396 int silc_packet_send(SilcSocketConnection sock, int force_send);
398 /****f* silccore/SilcPacketAPI/silc_packet_encrypt
402 * void silc_packet_encrypt(SilcCipher cipher, SilcHmac hmac,
403 * SilcBuffer buffer, uint32 len);
407 * Encrypts a packet. This also creates HMAC of the packet before
408 * encryption and adds the HMAC at the end of the buffer. This assumes
409 * that there is enough free space at the end of the buffer to add the
410 * computed HMAC. This is the normal way of encrypting packets, if some
411 * other process of HMAC computing and encryption is needed this function
415 void silc_packet_encrypt(SilcCipher cipher, SilcHmac hmac,
416 SilcBuffer buffer, uint32 len);
418 /****f* silccore/SilcPacketAPI/silc_packet_assemble
422 * void silc_packet_assemble(SilcPacketContext *ctx);
426 * Assembles a new packet to be ready for send out. The buffer sent as
427 * argument must include the data to be sent and it must not be encrypted.
428 * The packet also must have enough free space so that the SILC header
429 * and padding maybe added to the packet. The packet is encrypted after
430 * this function has returned.
432 * The buffer sent as argument should be something like following:
434 * --------------------------------------------
435 * | head | data | tail |
436 * --------------------------------------------
440 * So that the SILC header and 1 - 16 bytes of padding can fit to
441 * the buffer. After assembly the buffer might look like this:
443 * --------------------------------------------
445 * --------------------------------------------
447 * Start of assembled packet
449 * Packet construct is as follows (* = won't be encrypted):
451 * n bytes SILC Header
452 * 2 bytes Payload length (*)
455 * 2 bytes Source ID Length
456 * 2 bytes Destination ID Length
457 * 1 byte Source ID Type
459 * 1 byte Destination ID Type
460 * n bytes Destination ID
462 * 1 - 16 bytes Padding
464 * n bytes Data payload
466 * All fields in the packet will be authenticated by MAC. The MAC is
467 * not computed here, it must be computed separately before encrypting
471 void silc_packet_assemble(SilcPacketContext *ctx);
473 /****f* silccore/SilcPacketAPI/silc_packet_send_prepare
477 * void silc_packet_send_prepare(SilcSocketConnection sock,
484 * Prepare outgoing data buffer for packet sending. This moves the data
485 * area so that new packet may be added into it. If needed this allocates
486 * more space to the buffer. This handles directly the connection's
487 * outgoing buffer in SilcSocketConnection object.
490 void silc_packet_send_prepare(SilcSocketConnection sock,
495 /****f* silccore/SilcPacketAPI/silc_packet_read
499 * int silc_packet_read(int fd, SilcSocketConnection sock);
503 * Reads data from the socket connection into the incoming data buffer.
504 * However, this does not parse the packet, it only reads some amount from
505 * the network. If there are more data available that can be read at a time
506 * the rest of the data will be read later with a timeout and only after
507 * that the packet is ready to be parsed.
509 * The destination buffer sent as argument must be initialized before
510 * calling this function, and, the data section and the start of the tail
511 * section must be same. Ie. we add the read data to the tail section of
512 * the buffer hence the data section is the start of the buffer.
514 * This returns amount of bytes read or -1 on error or -2 on case where
515 * all of the data could not be read at once.
518 int silc_packet_read(int fd, SilcSocketConnection sock);
520 /****f* silccore/SilcPacketAPI/silc_packet_receive
524 * int silc_packet_receive(SilcSocketConnection sock);
528 * Receives packet from network and reads the data into connection's
529 * incoming data buffer. If the data was read directly this returns the
530 * read bytes, if error occured this returns -1, if the data could not
531 * be read directly at this time this returns -2 in which case the data
532 * should be read again at some later time, or If EOF occured this returns
536 int silc_packet_receive(SilcSocketConnection sock);
538 /****f* silccore/SilcPacketAPI/silc_packet_decrypt
542 * int silc_packet_decrypt(SilcCipher cipher, SilcHmac hmac,
543 * SilcBuffer buffer, SilcPacketContext *packet,
544 * SilcPacketCheckDecrypt check_packet,
549 * Decrypts a packet. This assumes that typical SILC packet is the
550 * packet to be decrypted and thus checks for normal and special SILC
551 * packets and can handle both of them. This also computes and checks
552 * the HMAC of the packet. If any other special or customized decryption
553 * processing is required this function cannot be used. This returns
554 * -1 on error, 0 when packet is normal packet and 1 when the packet
555 * is special and requires special processing.
557 * The `check_packet' is a callback funtion that this function will
558 * call. The callback relates to the checking whether the packet is
559 * normal packet or special packet and how it should be processed. If
560 * the callback return TRUE the packet is normal and FALSE if the packet
561 * is special and requires special procesing.
564 int silc_packet_decrypt(SilcCipher cipher, SilcHmac hmac,
565 SilcBuffer buffer, SilcPacketContext *packet,
566 SilcPacketCheckDecrypt check_packet,
569 /****f* silccore/SilcPacketAPI/silc_packet_receive_process
573 * void silc_packet_receive_process(SilcSocketConnection sock,
574 * SilcCipher cipher, SilcHmac hmac,
575 * SilcPacketParserCallback parser,
580 * Processes the received data. This checks the received data and
581 * calls parser callback that handles the actual packet decryption
582 * and parsing. If more than one packet was received this calls the
583 * parser multiple times. The parser callback will get context
584 * SilcPacketParserContext that includes the packet and the `context'
585 * sent to this function.
588 void silc_packet_receive_process(SilcSocketConnection sock,
589 SilcCipher cipher, SilcHmac hmac,
590 SilcPacketParserCallback parser,
593 /****f* silccore/SilcPacketAPI/silc_packet_parse
597 * SilcPacketType silc_packet_parse(SilcPacketContext *ctx);
601 * Parses the packet. This is called when a whole packet is ready to be
602 * parsed. The buffer sent must be already decrypted before calling this
603 * function. The len argument must be the true length of the packet. This
604 * function returns the type of the packet. The data section of the
605 * buffer is parsed, not head or tail sections.
608 SilcPacketType silc_packet_parse(SilcPacketContext *ctx);
610 /****f* silccore/SilcPacketAPI/silc_packet_parse_special
614 * SilcPacketType silc_packet_parse_special(SilcPacketContext *ctx);
618 * Perform special SILC Packet header parsing. This is required to some
619 * packet types that have the data payload encrypted with different key
620 * than the header area plus padding of the packet. Hence, this parses
621 * the header in a way that it does not take the data area into account
622 * and parses the header and padding area only.
625 SilcPacketType silc_packet_parse_special(SilcPacketContext *ctx);
627 /****f* silccore/SilcPacketAPI/silc_packet_context_alloc
631 * SilcPacketContext *silc_packet_context_alloc();
635 * Allocates a packet context. Packet contexts are used when
636 * packets are assembled and parsed. The context is freed by the
637 * silc_packet_context_free function.
640 SilcPacketContext *silc_packet_context_alloc();
642 /****f* silccore/SilcPacketAPI/silc_packet_context_dup
646 * SilcPacketContext *silc_packet_context_dup(SilcPacketContext *ctx);
650 * Duplicates the packet context. It actually does not duplicate
651 * any data, instead a reference counter is increased.
654 SilcPacketContext *silc_packet_context_dup(SilcPacketContext *ctx);
656 /****f* silccore/SilcPacketAPI/silc_packet_context_free
660 * void silc_packet_context_free(SilcPacketContext *ctx);
664 * Frees the packet context. The context is actually freed when the
665 * reference counter hits zero.
668 void silc_packet_context_free(SilcPacketContext *ctx);