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 /* Amount of bytes to be read from the socket connection at once. */
36 #define SILC_PACKET_READ_SIZE 16384
38 /* Default byte size of the packet. */
39 #define SILC_PACKET_DEFAULT_SIZE 1024
41 /* Header length without source and destination ID's. */
42 #define SILC_PACKET_HEADER_LEN 8 + 2
44 /* Minimum length of SILC Packet Header. This much is decrypted always
45 when packet is received to be able to get all the relevant data out
47 #define SILC_PACKET_MIN_HEADER_LEN 16 + 2
49 /* Maximum padding length */
50 #define SILC_PACKET_MAX_PADLEN 16
52 /* Minimum packet length */
53 #define SILC_PACKET_MIN_LEN (SILC_PACKET_HEADER_LEN + 1)
55 /* Maximum length of ID */
56 #define SILC_PACKET_MAX_ID_LEN 16
58 /****d* silccore/SilcPacketAPI/SilcPacketType
62 * typedef unsigned char SilcPacketType;
66 * SILC packet type definition and all the packet types.
70 typedef unsigned char SilcPacketType;
72 /* SILC Packet types. */
73 #define SILC_PACKET_NONE 0 /* NULL, never sent */
74 #define SILC_PACKET_DISCONNECT 1 /* Disconnection */
75 #define SILC_PACKET_SUCCESS 2 /* Success */
76 #define SILC_PACKET_FAILURE 3 /* Failure */
77 #define SILC_PACKET_REJECT 4 /* Rejected */
78 #define SILC_PACKET_NOTIFY 5 /* Notify message */
79 #define SILC_PACKET_ERROR 6 /* Error message */
80 #define SILC_PACKET_CHANNEL_MESSAGE 7 /* Message for channel */
81 #define SILC_PACKET_CHANNEL_KEY 8 /* Key of the channel */
82 #define SILC_PACKET_PRIVATE_MESSAGE 9 /* Private message */
83 #define SILC_PACKET_PRIVATE_MESSAGE_KEY 10 /* Private message key*/
84 #define SILC_PACKET_COMMAND 11 /* Command */
85 #define SILC_PACKET_COMMAND_REPLY 12 /* Reply to a command */
86 #define SILC_PACKET_KEY_EXCHANGE 13 /* Start of KE */
87 #define SILC_PACKET_KEY_EXCHANGE_1 14 /* KE1 */
88 #define SILC_PACKET_KEY_EXCHANGE_2 15 /* KE2 */
89 #define SILC_PACKET_CONNECTION_AUTH_REQUEST 16 /* Request of auth meth */
90 #define SILC_PACKET_CONNECTION_AUTH 17 /* Connectinon auth */
91 #define SILC_PACKET_NEW_ID 18 /* Sending new ID */
92 #define SILC_PACKET_NEW_CLIENT 19 /* Client registering */
93 #define SILC_PACKET_NEW_SERVER 20 /* Server registering */
94 #define SILC_PACKET_NEW_CHANNEL 21 /* Channel registering */
95 #define SILC_PACKET_REKEY 22 /* Re-key start */
96 #define SILC_PACKET_REKEY_DONE 23 /* Re-key done */
97 #define SILC_PACKET_HEARTBEAT 24 /* Heartbeat */
98 #define SILC_PACKET_KEY_AGREEMENT 25 /* Key Agreement request */
99 #define SILC_PACKET_CELL_ROUTERS 26 /* Cell routers backup */
101 #define SILC_PACKET_PRIVATE 200 /* Private range start */
102 #define SILC_PACKET_MAX 255 /* RESERVED */
105 /****d* silccore/SilcPacketAPI/SilcPacketVersion
109 * typedef unsigned char SilcPacketVersion;
113 * SILC packet version type definition.
116 typedef unsigned char SilcPacketVersion;
118 /****d* silccore/SilcPacketAPI/SilcPacketFlags
122 * typedef unsigned char SilcPacketFlags;
126 * SILC packet flags type definition and all the packet flags.
130 typedef unsigned char SilcPacketFlags;
132 /* All defined packet flags */
133 #define SILC_PACKET_FLAG_NONE 0x00 /* No flags */
134 #define SILC_PACKET_FLAG_PRIVMSG_KEY 0x01 /* Private message key */
135 #define SILC_PACKET_FLAG_LIST 0x02 /* Packet is a list */
136 #define SILC_PACKET_FLAG_BROADCAST 0x04 /* Packet is a broadcast */
139 /* Rest of flags still available
140 #define SILC_PACKET_FLAG_XXX 0x08
141 #define SILC_PACKET_FLAG_XXX 0x10
142 #define SILC_PACKET_FLAG_XXX 0x20
143 #define SILC_PACKET_FLAG_XXX 0x40
144 #define SILC_PACKET_FLAG_XXX 0x80
147 /****s* silccore/SilcPacketAPI/SilcPacketContext
151 * typedef struct { ... } SilcPacketContext;
155 * In packet sending this is filled and sent to silc_packet_assemble
156 * which then uses it to assemble new packet. In packet reception pointer
157 * to this context is sent to silc_packet_parse which parses the packet
158 * and returns the relevant information to this structure. On packet
159 * reception returned ID's are always the hash values of the ID's from
162 * Short description of the fields following:
168 * SilcPacketType type
170 * Type of the packet. Types are defined below.
172 * SilcPacketFlags flags
174 * Packet flags. Flags are defined above.
176 * unsigned char *src_id
178 * unsigned char src_id_type
180 * Source ID, its length and type. On packet reception retuned ID's
181 * are always the hash values of the ID's from the packet.
183 * unsigned char *dst_id;
185 * unsigned char src_id_type;
187 * Destination ID, its length and type. On packet reception retuned
188 * ID's are always the hash values of the ID's from the packet.
193 * The true lenght of the packet and the padded length of the packet.
194 * These may be set by the caller before calling any of the
195 * silc_packet_* routines. If not provided the library will calculate
200 * Reference counter for this context. The context is freed only
201 * after the reference counter hits zero. The counter is added
202 * calling silc_packet_context_dup and decreased by calling the
203 * silc_packet_context_free.
209 SilcPacketFlags flags;
211 unsigned char *src_id;
213 unsigned char src_id_type;
215 unsigned char *dst_id;
217 unsigned char dst_id_type;
224 SilcSocketConnection sock;
229 /****s* silccore/SilcPacketAPI/SilcPacketParserContext
233 * typedef struct { ... } SilcPacketParserContext;
237 * This context is used in packet reception when silc_packet_receive_process
238 * function calls parser callback that performs the actual packet decryption
239 * and parsing. This context is sent as argument to the parser function.
240 * This context must be free'd by the parser callback function.
242 * Following description of the fields:
244 * SilcPacketContext *packet
246 * The actual packet received from the network. In this phase the
247 * context is not parsed, only the packet->buffer is allocated and
248 * it includes the raw packet data, which is encrypted.
250 * SilcSocketConnection sock
252 * The associated connection.
256 * User context that is sent to the silc_packet_receive_process
257 * function. This usually includes application and connection specific
262 SilcPacketContext *packet;
263 SilcSocketConnection sock;
265 } SilcPacketParserContext;
267 /****f* silccore/SilcPacketAPI/SilcPacketParserCallback
271 * typedef void (*SilcPacketParserCallback)(SilcPacketParserContext
276 * This callback is given to the silc_packet_receive_process function.
277 * The callback is called by the library every time a packet is
278 * received from the network. After the packet has been decrypted
279 * and at least partially parsed it is passed to the application
280 * for further parsing using this callback and the SilcPacketParserContext
281 * context. The application receiving the SilcPacketParserContext
285 typedef void (*SilcPacketParserCallback)(SilcPacketParserContext
288 /****f* silccore/SilcPacketAPI/SilcPacketCheckDecrypt
292 * typedef int (*SilcPacketCheckDecrypt)(SilcPacketType packet_type,
294 * SilcPacketContext *packet,
299 * This callback function relates to the checking whether the packet is
300 * normal packet or special packet and how it should be processed. If
301 * the callback returns TRUE the packet is normal and FALSE if the packet
302 * is special and requires special procesing. Some of the packets in
303 * SILC are special (like channel message packets that are encrypted
304 * using channel specific keys) and requires special processing. That
305 * is the reason for this callback function.
307 * The library will call this function if provided for the
308 * silc_packet_decrypt function. The `packet_type' is the type of
309 * packet received (this is also actually the first time application
310 * receives information of the received packet, next time it receives
311 * it is when the SilcPacketParserCallback function is called),
312 * the `buffer' is the raw packet data the `packet' the allocated
313 * SilcPacketContext that is filled when parsing the packet and `context'
314 * is application specific user context.
317 typedef int (*SilcPacketCheckDecrypt)(SilcPacketType packet_type,
319 SilcPacketContext *packet,
324 /****d* silccore/SilcPacketAPI/SILC_PACKET_LENGTH
328 * #define SILC_PACKET_LENGTH ...
332 * Returns true length of the packet and padded length of the packet.
333 * This is primarily used by the libary in packet parsing phase but
334 * the application may use it as well if needed.
338 #define SILC_PACKET_LENGTH(__packet, __ret_truelen, __ret_padlen) \
340 SILC_GET16_MSB((__ret_truelen), (__packet)->data); \
341 (__ret_padlen) = (((__ret_truelen) - 2) + \
342 SILC_PACKET_MAX_PADLEN) & ~(SILC_PACKET_MAX_PADLEN - 1); \
346 /****d* silccore/SilcPacketAPI/SILC_PACKET_PADLEN
350 * #define SILC_PACKET_PADLEN ...
354 * Returns the length of the padding in the packet. This is used
355 * by various library routines to determine needed padding length.
359 #define SILC_PACKET_PADLEN(__packetlen) \
360 SILC_PACKET_MAX_PADLEN - ((__packetlen) - 2) % SILC_PACKET_MAX_PADLEN;
365 /****f* silccore/SilcPacketAPI/silc_packet_write
369 * int silc_packet_write(int sock, SilcBuffer src);
373 * Writes data from encrypted buffer to the socket connection. If the
374 * data cannot be written at once, it will be written later with a timeout.
375 * The data is written from the data section of the buffer, not from head
376 * or tail section. This automatically pulls the data section towards end
377 * after writing the data.
380 int silc_packet_write(int sock, SilcBuffer src);
382 /****f* silccore/SilcPacketAPI/silc_packet_send
386 * int silc_packet_send(SilcSocketConnection sock, int force_send);
390 * Actually sends the packet. This flushes the connections outgoing data
391 * buffer. If data is sent directly to the network this returns the bytes
392 * written, if error occured this returns -1 and if the data could not
393 * be written directly to the network at this time this returns -2, in
394 * which case the data should be queued by the caller and sent at some
395 * later time. If `force_send' is TRUE this attempts to write the data
396 * directly to the network, if FALSE, this returns -2.
399 int silc_packet_send(SilcSocketConnection sock, int force_send);
401 /****f* silccore/SilcPacketAPI/silc_packet_encrypt
405 * void silc_packet_encrypt(SilcCipher cipher, SilcHmac hmac,
406 * SilcBuffer buffer, uint32 len);
410 * Encrypts a packet. This also creates HMAC of the packet before
411 * encryption and adds the HMAC at the end of the buffer. This assumes
412 * that there is enough free space at the end of the buffer to add the
413 * computed HMAC. This is the normal way of encrypting packets, if some
414 * other process of HMAC computing and encryption is needed this function
418 void silc_packet_encrypt(SilcCipher cipher, SilcHmac hmac,
419 SilcBuffer buffer, uint32 len);
421 /****f* silccore/SilcPacketAPI/silc_packet_assemble
425 * void silc_packet_assemble(SilcPacketContext *ctx);
429 * Assembles a new packet to be ready for send out. The buffer sent as
430 * argument must include the data to be sent and it must not be encrypted.
431 * The packet also must have enough free space so that the SILC header
432 * and padding maybe added to the packet. The packet is encrypted after
433 * this function has returned.
435 * The buffer sent as argument should be something like following:
437 * --------------------------------------------
438 * | head | data | tail |
439 * --------------------------------------------
443 * So that the SILC header and 1 - 16 bytes of padding can fit to
444 * the buffer. After assembly the buffer might look like this:
446 * --------------------------------------------
448 * --------------------------------------------
450 * Start of assembled packet
452 * Packet construct is as follows (* = won't be encrypted):
454 * n bytes SILC Header
455 * 2 bytes Payload length (*)
458 * 2 bytes Source ID Length
459 * 2 bytes Destination ID Length
460 * 1 byte Source ID Type
462 * 1 byte Destination ID Type
463 * n bytes Destination ID
465 * 1 - 16 bytes Padding
467 * n bytes Data payload
469 * All fields in the packet will be authenticated by MAC. The MAC is
470 * not computed here, it must be computed separately before encrypting
474 void silc_packet_assemble(SilcPacketContext *ctx);
476 /****f* silccore/SilcPacketAPI/silc_packet_send_prepare
480 * void silc_packet_send_prepare(SilcSocketConnection sock,
487 * Prepare outgoing data buffer for packet sending. This moves the data
488 * area so that new packet may be added into it. If needed this allocates
489 * more space to the buffer. This handles directly the connection's
490 * outgoing buffer in SilcSocketConnection object.
493 void silc_packet_send_prepare(SilcSocketConnection sock,
498 /****f* silccore/SilcPacketAPI/silc_packet_read
502 * int silc_packet_read(int fd, SilcSocketConnection sock);
506 * Reads data from the socket connection into the incoming data buffer.
507 * However, this does not parse the packet, it only reads some amount from
508 * the network. If there are more data available that can be read at a time
509 * the rest of the data will be read later with a timeout and only after
510 * that the packet is ready to be parsed.
512 * The destination buffer sent as argument must be initialized before
513 * calling this function, and, the data section and the start of the tail
514 * section must be same. Ie. we add the read data to the tail section of
515 * the buffer hence the data section is the start of the buffer.
517 * This returns amount of bytes read or -1 on error or -2 on case where
518 * all of the data could not be read at once.
521 int silc_packet_read(int fd, SilcSocketConnection sock);
523 /****f* silccore/SilcPacketAPI/silc_packet_receive
527 * int silc_packet_receive(SilcSocketConnection sock);
531 * Receives packet from network and reads the data into connection's
532 * incoming data buffer. If the data was read directly this returns the
533 * read bytes, if error occured this returns -1, if the data could not
534 * be read directly at this time this returns -2 in which case the data
535 * should be read again at some later time, or If EOF occured this returns
539 int silc_packet_receive(SilcSocketConnection sock);
541 /****f* silccore/SilcPacketAPI/silc_packet_decrypt
545 * int silc_packet_decrypt(SilcCipher cipher, SilcHmac hmac,
546 * SilcBuffer buffer, SilcPacketContext *packet,
547 * SilcPacketCheckDecrypt check_packet,
552 * Decrypts a packet. This assumes that typical SILC packet is the
553 * packet to be decrypted and thus checks for normal and special SILC
554 * packets and can handle both of them. This also computes and checks
555 * the HMAC of the packet. If any other special or customized decryption
556 * processing is required this function cannot be used. This returns
557 * -1 on error, 0 when packet is normal packet and 1 when the packet
558 * is special and requires special processing.
560 * The `check_packet' is a callback funtion that this function will
561 * call. The callback relates to the checking whether the packet is
562 * normal packet or special packet and how it should be processed. If
563 * the callback return TRUE the packet is normal and FALSE if the packet
564 * is special and requires special procesing.
567 int silc_packet_decrypt(SilcCipher cipher, SilcHmac hmac,
568 SilcBuffer buffer, SilcPacketContext *packet,
569 SilcPacketCheckDecrypt check_packet,
572 /****f* silccore/SilcPacketAPI/silc_packet_receive_process
576 * void silc_packet_receive_process(SilcSocketConnection sock,
577 * SilcCipher cipher, SilcHmac hmac,
578 * SilcPacketParserCallback parser,
583 * Processes the received data. This checks the received data and
584 * calls parser callback that handles the actual packet decryption
585 * and parsing. If more than one packet was received this calls the
586 * parser multiple times. The parser callback will get context
587 * SilcPacketParserContext that includes the packet and the `context'
588 * sent to this function.
591 void silc_packet_receive_process(SilcSocketConnection sock,
592 SilcCipher cipher, SilcHmac hmac,
593 SilcPacketParserCallback parser,
596 /****f* silccore/SilcPacketAPI/silc_packet_parse
600 * SilcPacketType silc_packet_parse(SilcPacketContext *ctx);
604 * Parses the packet. This is called when a whole packet is ready to be
605 * parsed. The buffer sent must be already decrypted before calling this
606 * function. The len argument must be the true length of the packet. This
607 * function returns the type of the packet. The data section of the
608 * buffer is parsed, not head or tail sections.
611 SilcPacketType silc_packet_parse(SilcPacketContext *ctx);
613 /****f* silccore/SilcPacketAPI/silc_packet_parse_special
617 * SilcPacketType silc_packet_parse_special(SilcPacketContext *ctx);
621 * Perform special SILC Packet header parsing. This is required to some
622 * packet types that have the data payload encrypted with different key
623 * than the header area plus padding of the packet. Hence, this parses
624 * the header in a way that it does not take the data area into account
625 * and parses the header and padding area only.
628 SilcPacketType silc_packet_parse_special(SilcPacketContext *ctx);
630 /****f* silccore/SilcPacketAPI/silc_packet_context_alloc
634 * SilcPacketContext *silc_packet_context_alloc();
638 * Allocates a packet context. Packet contexts are used when
639 * packets are assembled and parsed. The context is freed by the
640 * silc_packet_context_free function.
643 SilcPacketContext *silc_packet_context_alloc();
645 /****f* silccore/SilcPacketAPI/silc_packet_context_dup
649 * SilcPacketContext *silc_packet_context_dup(SilcPacketContext *ctx);
653 * Duplicates the packet context. It actually does not duplicate
654 * any data, instead a reference counter is increased.
657 SilcPacketContext *silc_packet_context_dup(SilcPacketContext *ctx);
659 /****f* silccore/SilcPacketAPI/silc_packet_context_free
663 * void silc_packet_context_free(SilcPacketContext *ctx);
667 * Frees the packet context. The context is actually freed when the
668 * reference counter hits zero.
671 void silc_packet_context_free(SilcPacketContext *ctx);