5 Author: Pekka Riikonen <priikone@silcnet.org>
7 Copyright (C) 1997 - 2001 Pekka Riikonen
9 This program is free software; you can redistribute it and/or modify
10 it under the terms of the GNU General Public License as published by
11 the Free Software Foundation; version 2 of the License.
13 This program is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
20 /****h* silccore/SilcPacketAPI
24 * Implementation of the packet routines for sending and receiving
25 * SILC Packets. These includes the data sending routines and data
26 * reading routines, encrypting and decrypting routines, packet assembling
27 * and packet parsing routines.
34 /* Default byte size of the packet. */
35 #define SILC_PACKET_DEFAULT_SIZE SILC_SOCKET_BUF_SIZE
37 /* Header length without source and destination ID's. */
38 #define SILC_PACKET_HEADER_LEN 10
40 /* Minimum length of SILC Packet Header. This much is decrypted always
41 when packet is received to be able to get all the relevant data out
43 #define SILC_PACKET_MIN_HEADER_LEN 16
45 /* Maximum padding length */
46 #define SILC_PACKET_MAX_PADLEN 16
48 /* Minimum packet length */
49 #define SILC_PACKET_MIN_LEN (SILC_PACKET_HEADER_LEN + 1)
51 /* Maximum length of ID */
52 #define SILC_PACKET_MAX_ID_LEN 16
54 /****d* silccore/SilcPacketAPI/SilcPacketType
58 * typedef unsigned char SilcPacketType;
62 * SILC packet type definition and all the packet types.
66 typedef unsigned char SilcPacketType;
68 /* SILC Packet types. */
69 #define SILC_PACKET_NONE 0 /* NULL, never sent */
70 #define SILC_PACKET_DISCONNECT 1 /* Disconnection */
71 #define SILC_PACKET_SUCCESS 2 /* Success */
72 #define SILC_PACKET_FAILURE 3 /* Failure */
73 #define SILC_PACKET_REJECT 4 /* Rejected */
74 #define SILC_PACKET_NOTIFY 5 /* Notify message */
75 #define SILC_PACKET_ERROR 6 /* Error message */
76 #define SILC_PACKET_CHANNEL_MESSAGE 7 /* Message for channel */
77 #define SILC_PACKET_CHANNEL_KEY 8 /* Key of the channel */
78 #define SILC_PACKET_PRIVATE_MESSAGE 9 /* Private message */
79 #define SILC_PACKET_PRIVATE_MESSAGE_KEY 10 /* Private message key*/
80 #define SILC_PACKET_COMMAND 11 /* Command */
81 #define SILC_PACKET_COMMAND_REPLY 12 /* Reply to a command */
82 #define SILC_PACKET_KEY_EXCHANGE 13 /* Start of KE */
83 #define SILC_PACKET_KEY_EXCHANGE_1 14 /* KE1 */
84 #define SILC_PACKET_KEY_EXCHANGE_2 15 /* KE2 */
85 #define SILC_PACKET_CONNECTION_AUTH_REQUEST 16 /* Request of auth meth */
86 #define SILC_PACKET_CONNECTION_AUTH 17 /* Connectinon auth */
87 #define SILC_PACKET_NEW_ID 18 /* Sending new ID */
88 #define SILC_PACKET_NEW_CLIENT 19 /* Client registering */
89 #define SILC_PACKET_NEW_SERVER 20 /* Server registering */
90 #define SILC_PACKET_NEW_CHANNEL 21 /* Channel registering */
91 #define SILC_PACKET_REKEY 22 /* Re-key start */
92 #define SILC_PACKET_REKEY_DONE 23 /* Re-key done */
93 #define SILC_PACKET_HEARTBEAT 24 /* Heartbeat */
94 #define SILC_PACKET_KEY_AGREEMENT 25 /* Key Agreement request */
95 #define SILC_PACKET_RESUME_ROUTER 26 /* Backup router resume */
96 #define SILC_PACKET_FTP 27 /* File Transfer */
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.
204 * Packet sequence number.
210 SilcPacketFlags flags;
212 unsigned char *src_id;
214 unsigned char src_id_type;
216 unsigned char *dst_id;
218 unsigned char dst_id_type;
225 SilcSocketConnection sock;
231 /* XXX backwards support for 0.5.c
232 XXX remove in 0.7.x */
236 /****s* silccore/SilcPacketAPI/SilcPacketParserContext
240 * typedef struct { ... } SilcPacketParserContext;
244 * This context is used in packet reception when the function
245 * silc_packet_receive_process calls parser callback that performs
246 * the actual packet decryption and parsing. This context is sent as
247 * argument to the parser function. This context must be free'd by
248 * the parser callback function.
250 * Following description of the fields:
252 * SilcPacketContext *packet
254 * The actual packet received from the network. In this phase the
255 * context is not parsed, only the packet->buffer is allocated and
256 * it includes the raw packet data, which is encrypted.
260 * Indicates whether the received packet is normal or special packet.
261 * If special the parsing process is special also.
263 * SilcSocketConnection sock
265 * The associated connection.
269 * User context that is sent to the silc_packet_receive_process
270 * function. This usually includes application and connection specific
275 SilcPacketContext *packet;
277 SilcSocketConnection sock;
279 } SilcPacketParserContext;
281 /****f* silccore/SilcPacketAPI/SilcPacketParserCallback
285 * typedef void (*SilcPacketParserCallback)(SilcPacketParserContext
290 * This callback is given to the silc_packet_receive_process function.
291 * The callback is called by the library every time a packet is
292 * received from the network. After the packet has been decrypted
293 * and at least partially parsed it is passed to the application
294 * for further parsing using this callback and the SilcPacketParserContext
295 * context. The application receiving the SilcPacketParserContext
299 typedef void (*SilcPacketParserCallback)(SilcPacketParserContext
300 *parse_context, void *context);
304 /****d* silccore/SilcPacketAPI/SILC_PACKET_LENGTH
308 * #define SILC_PACKET_LENGTH ...
312 * Returns true length of the packet. This is primarily used by the
313 * libary in packet parsing phase but the application may use it as
318 #define SILC_PACKET_LENGTH(__packet, __ret_truelen) \
320 SILC_GET16_MSB((__ret_truelen), (__packet)->data); \
324 /****d* silccore/SilcPacketAPI/SILC_PACKET_PADLEN
328 * #define SILC_PACKET_PADLEN ...
332 * Returns the length of the padding in the packet. This is used
333 * by various library routines to determine needed padding length.
337 #define SILC_PACKET_PADLEN(__packetlen, __blocklen) \
338 SILC_PACKET_MAX_PADLEN - (__packetlen) % \
339 ((__blocklen) ? (__blocklen) : SILC_PACKET_MAX_PADLEN)
342 /* XXX Backwards support for 0.5.x
343 XXX Remove in 0.7.x */
344 #define SILC_PACKET_PADLEN2(__packetlen, __blocklen) \
345 SILC_PACKET_MAX_PADLEN - ((__packetlen) - 2 ) % \
346 ((__blocklen) ? (__blocklen) : SILC_PACKET_MAX_PADLEN)
350 /****f* silccore/SilcPacketAPI/silc_packet_send
354 * int silc_packet_send(SilcSocketConnection sock, bool force_send);
358 * Actually sends the packet. This flushes the connections outgoing data
359 * buffer. If data is sent directly to the network this returns the bytes
360 * written, if error occured this returns -1 and if the data could not
361 * be written directly to the network at this time this returns -2, in
362 * which case the data should be queued by the caller and sent at some
363 * later time. If `force_send' is TRUE this attempts to write the data
364 * directly to the network, if FALSE, this returns -2.
367 int silc_packet_send(SilcSocketConnection sock, bool force_send);
369 /****f* silccore/SilcPacketAPI/silc_packet_encrypt
373 * void silc_packet_encrypt(SilcCipher cipher, SilcHmac hmac,
374 * SilcBuffer buffer, uint32 len);
378 * Encrypts a packet. This also creates HMAC of the packet before
379 * encryption and adds the HMAC at the end of the buffer. This assumes
380 * that there is enough free space at the end of the buffer to add the
381 * computed HMAC. This is the normal way of encrypting packets, if some
382 * other process of HMAC computing and encryption is needed this function
386 void silc_packet_encrypt(SilcCipher cipher, SilcHmac hmac, uint32 sequence,
387 SilcBuffer buffer, uint32 len);
389 /****f* silccore/SilcPacketAPI/silc_packet_assemble
393 * void silc_packet_assemble(SilcPacketContext *ctx);
397 * Assembles a new packet to be ready for send out. The buffer sent as
398 * argument must include the data to be sent and it must not be encrypted.
399 * The packet also must have enough free space so that the SILC header
400 * and padding maybe added to the packet. The packet is encrypted after
401 * this function has returned.
403 * The buffer sent as argument should be something like following:
405 * --------------------------------------------
406 * | head | data | tail |
407 * --------------------------------------------
411 * So that the SILC header and 1 - 16 bytes of padding can fit to
412 * the buffer. After assembly the buffer might look like this:
414 * --------------------------------------------
416 * --------------------------------------------
418 * Start of assembled packet
420 * Packet construct is as follows (* = won't be encrypted):
422 * n bytes SILC Header
423 * 2 bytes Payload length (*)
426 * 2 bytes Source ID Length
427 * 2 bytes Destination ID Length
428 * 1 byte Source ID Type
430 * 1 byte Destination ID Type
431 * n bytes Destination ID
433 * 1 - 16 bytes Padding
435 * n bytes Data payload
437 * All fields in the packet will be authenticated by MAC. The MAC is
438 * not computed here, it must be computed separately before encrypting
442 void silc_packet_assemble(SilcPacketContext *ctx, SilcCipher cipher);
444 /****f* silccore/SilcPacketAPI/silc_packet_send_prepare
448 * void silc_packet_send_prepare(SilcSocketConnection sock,
455 * Prepare outgoing data buffer for packet sending. This moves the data
456 * area so that new packet may be added into it. If needed this allocates
457 * more space to the buffer. This handles directly the connection's
458 * outgoing buffer in SilcSocketConnection object.
461 void silc_packet_send_prepare(SilcSocketConnection sock,
466 /****f* silccore/SilcPacketAPI/silc_packet_receive
470 * int silc_packet_receive(SilcSocketConnection sock);
474 * Receives packet from network and reads the data into connection's
475 * incoming data buffer. If the data was read directly this returns the
476 * read bytes, if error occured this returns -1, if the data could not
477 * be read directly at this time this returns -2 in which case the data
478 * should be read again at some later time, or If EOF occured this returns
482 int silc_packet_receive(SilcSocketConnection sock);
484 /****f* silccore/SilcPacketAPI/silc_packet_receive_process
488 * void silc_packet_receive_process(SilcSocketConnection sock,
489 * bool local_is_router,
490 * SilcCipher cipher, SilcHmac hmac,
491 * SilcPacketParserCallback parser,
492 * void *parser_context);
496 * Processes and decrypts the incmoing data, and calls parser callback
497 * for each received packet that will handle the actual packet parsing.
498 * If more than one packet was received this calls the parser multiple
499 * times. The parser callback will get context SilcPacketParserContext
500 * that includes the packet and the `parser_context' sent to this
503 * The `local_is_router' indicates whether the caller is router server
504 * in which case the receiving process of a certain packet types may
505 * be special. Normal server and client must set it to FALSE. The
506 * SilcPacketParserContext will indicate also whether the received
507 * packet was normal or special packet.
510 void silc_packet_receive_process(SilcSocketConnection sock,
511 bool local_is_router,
512 SilcCipher cipher, SilcHmac hmac,
514 SilcPacketParserCallback parser,
515 void *parser_context);
517 /****f* silccore/SilcPacketAPI/silc_packet_parse
521 * SilcPacketType silc_packet_parse(SilcPacketContext *ctx);
525 * Parses the packet. This is called when a whole packet is ready to be
526 * parsed. The buffer sent must be already decrypted before calling this
527 * function. The len argument must be the true length of the packet. This
528 * function returns the type of the packet. The data section of the
529 * buffer is parsed, not head or tail sections.
532 SilcPacketType silc_packet_parse(SilcPacketContext *ctx, SilcCipher cipher);
534 /****f* silccore/SilcPacketAPI/silc_packet_parse_special
538 * SilcPacketType silc_packet_parse_special(SilcPacketContext *ctx);
542 * Perform special SILC Packet header parsing. This is required to some
543 * packet types that have the data payload encrypted with different key
544 * than the header area plus padding of the packet. Hence, this parses
545 * the header in a way that it does not take the data area into account
546 * and parses the header and padding area only.
549 SilcPacketType silc_packet_parse_special(SilcPacketContext *ctx,
552 /****f* silccore/SilcPacketAPI/silc_packet_context_alloc
556 * SilcPacketContext *silc_packet_context_alloc();
560 * Allocates a packet context. Packet contexts are used when
561 * packets are assembled and parsed. The context is freed by the
562 * silc_packet_context_free function.
565 SilcPacketContext *silc_packet_context_alloc(void);
567 /****f* silccore/SilcPacketAPI/silc_packet_context_dup
571 * SilcPacketContext *silc_packet_context_dup(SilcPacketContext *ctx);
575 * Duplicates the packet context. It actually does not duplicate
576 * any data, instead a reference counter is increased.
579 SilcPacketContext *silc_packet_context_dup(SilcPacketContext *ctx);
581 /****f* silccore/SilcPacketAPI/silc_packet_context_free
585 * void silc_packet_context_free(SilcPacketContext *ctx);
589 * Frees the packet context. The context is actually freed when the
590 * reference counter hits zero.
593 void silc_packet_context_free(SilcPacketContext *ctx);