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/Packet Protocol Interface
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 128
48 /* Default padding length */
49 #define SILC_PACKET_DEFAULT_PADLEN 16
51 /* Minimum packet length */
52 #define SILC_PACKET_MIN_LEN (SILC_PACKET_HEADER_LEN + 1)
54 /* Maximum packet length */
55 #define SILC_PACKET_MAX_LEN 0xffff
57 /* Maximum length of ID */
58 #define SILC_PACKET_MAX_ID_LEN 16
60 /****d* silccore/SilcPacketAPI/SilcPacketType
64 * typedef unsigned char SilcPacketType;
68 * SILC packet type definition and all the packet types.
72 typedef unsigned char SilcPacketType;
74 /* SILC Packet types. */
75 #define SILC_PACKET_NONE 0 /* NULL, never sent */
76 #define SILC_PACKET_DISCONNECT 1 /* Disconnection */
77 #define SILC_PACKET_SUCCESS 2 /* Success */
78 #define SILC_PACKET_FAILURE 3 /* Failure */
79 #define SILC_PACKET_REJECT 4 /* Rejected */
80 #define SILC_PACKET_NOTIFY 5 /* Notify message */
81 #define SILC_PACKET_ERROR 6 /* Error message */
82 #define SILC_PACKET_CHANNEL_MESSAGE 7 /* Message for channel */
83 #define SILC_PACKET_CHANNEL_KEY 8 /* Key of the channel */
84 #define SILC_PACKET_PRIVATE_MESSAGE 9 /* Private message */
85 #define SILC_PACKET_PRIVATE_MESSAGE_KEY 10 /* Private message key*/
86 #define SILC_PACKET_COMMAND 11 /* Command */
87 #define SILC_PACKET_COMMAND_REPLY 12 /* Reply to a command */
88 #define SILC_PACKET_KEY_EXCHANGE 13 /* Start of KE */
89 #define SILC_PACKET_KEY_EXCHANGE_1 14 /* KE1 */
90 #define SILC_PACKET_KEY_EXCHANGE_2 15 /* KE2 */
91 #define SILC_PACKET_CONNECTION_AUTH_REQUEST 16 /* Request of auth meth */
92 #define SILC_PACKET_CONNECTION_AUTH 17 /* Connectinon auth */
93 #define SILC_PACKET_NEW_ID 18 /* Sending new ID */
94 #define SILC_PACKET_NEW_CLIENT 19 /* Client registering */
95 #define SILC_PACKET_NEW_SERVER 20 /* Server registering */
96 #define SILC_PACKET_NEW_CHANNEL 21 /* Channel registering */
97 #define SILC_PACKET_REKEY 22 /* Re-key start */
98 #define SILC_PACKET_REKEY_DONE 23 /* Re-key done */
99 #define SILC_PACKET_HEARTBEAT 24 /* Heartbeat */
100 #define SILC_PACKET_KEY_AGREEMENT 25 /* Key Agreement request */
101 #define SILC_PACKET_RESUME_ROUTER 26 /* Backup router resume */
102 #define SILC_PACKET_FTP 27 /* File Transfer */
104 #define SILC_PACKET_PRIVATE 200 /* Private range start */
105 #define SILC_PACKET_MAX 255 /* RESERVED */
108 /****d* silccore/SilcPacketAPI/SilcPacketVersion
112 * typedef unsigned char SilcPacketVersion;
116 * SILC packet version type definition.
119 typedef unsigned char SilcPacketVersion;
121 /****d* silccore/SilcPacketAPI/SilcPacketFlags
125 * typedef unsigned char SilcPacketFlags;
129 * SILC packet flags type definition and all the packet flags.
133 typedef unsigned char SilcPacketFlags;
135 /* All defined packet flags */
136 #define SILC_PACKET_FLAG_NONE 0x00 /* No flags */
137 #define SILC_PACKET_FLAG_PRIVMSG_KEY 0x01 /* Private message key */
138 #define SILC_PACKET_FLAG_LIST 0x02 /* Packet is a list */
139 #define SILC_PACKET_FLAG_BROADCAST 0x04 /* Packet is a broadcast */
142 /* Rest of flags still available
143 #define SILC_PACKET_FLAG_XXX 0x08
144 #define SILC_PACKET_FLAG_XXX 0x10
145 #define SILC_PACKET_FLAG_XXX 0x20
146 #define SILC_PACKET_FLAG_XXX 0x40
147 #define SILC_PACKET_FLAG_XXX 0x80
150 /****s* silccore/SilcPacketAPI/SilcPacketContext
154 * typedef struct { ... } SilcPacketContext;
158 * In packet sending this is filled and sent to silc_packet_assemble
159 * which then uses it to assemble new packet. In packet reception pointer
160 * to this context is sent to silc_packet_parse which parses the packet
161 * and returns the relevant information to this structure. On packet
162 * reception returned ID's are always the hash values of the ID's from
165 * Short description of the fields following:
171 * SilcPacketType type
173 * Type of the packet. Types are defined below.
175 * SilcPacketFlags flags
177 * Packet flags. Flags are defined above.
179 * unsigned char *src_id
180 * SilcUInt8 src_id_len
181 * unsigned char src_id_type
183 * Source ID, its length and type. On packet reception retuned ID's
184 * are always the hash values of the ID's from the packet.
186 * unsigned char *dst_id;
187 * SilcUInt8 dst_id_len;
188 * unsigned char src_id_type;
190 * Destination ID, its length and type. On packet reception retuned
191 * ID's are always the hash values of the ID's from the packet.
196 * The true lenght of the packet and the padded length of the packet.
197 * These may be set by the caller before calling any of the
198 * silc_packet_* routines. If not provided the library will calculate
203 * Reference counter for this context. The context is freed only
204 * after the reference counter hits zero. The counter is added
205 * calling silc_packet_context_dup and decreased by calling the
206 * silc_packet_context_free.
208 * SilcUInt32 sequence;
210 * Packet sequence number.
217 SilcPacketFlags flags;
221 unsigned char *src_id;
222 SilcUInt8 src_id_len;
223 SilcUInt8 src_id_type;
225 unsigned char *dst_id;
226 SilcUInt8 dst_id_len;
227 SilcUInt8 dst_id_type;
230 bool long_pad; /* Set to TRUE to use maximum padding
231 in packet (up to 256 bytes). */
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 bool (*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
298 * This returns TRUE if the library should continue packet processing
299 * (assuming there is more data to be processed), and FALSE if the
300 * upper layer does not want the library to continue but to leave the
301 * rest of the data is the packet queue untouched. Application may
302 * want to do this for example if the cipher is not ready before
303 * processing a certain packet. In this case the application wants
304 * to recall the processing function with the correct cipher.
307 typedef bool (*SilcPacketParserCallback)(SilcPacketParserContext
308 *parse_context, void *context);
312 /****d* silccore/SilcPacketAPI/SILC_PACKET_LENGTH
316 * #define SILC_PACKET_LENGTH ...
320 * Returns true length of the packet. This is primarily used by the
321 * libary in packet parsing phase but the application may use it as
326 #define SILC_PACKET_LENGTH(__packet, __ret_truelen, __ret_paddedlen) \
328 SILC_GET16_MSB((__ret_truelen), (__packet)->data); \
329 (__ret_paddedlen) = (__ret_truelen) + (__packet)->data[4]; \
333 /****d* silccore/SilcPacketAPI/SILC_PACKET_DATALEN
337 * #define SILC_PACKET_DATALEN ...
341 * Calculates the data length with given header length. This macro
342 * can be used to check whether the data_len with header_len exceeds
343 * SILC_PACKET_MAX_LEN. If it does, this returns the new data_len
344 * so that the SILC_PACKET_MAX_LEN is not exceeded. If the data_len
345 * plus header_len fits SILC_PACKET_MAX_LEN the returned data length
346 * is the data_len given as argument. This macro can be used when
351 #define SILC_PACKET_DATALEN(data_len, header_len) \
352 ((data_len + header_len) > SILC_PACKET_MAX_LEN ? \
353 data_len - ((data_len + header_len) - SILC_PACKET_MAX_LEN) : data_len)
356 /****d* silccore/SilcPacketAPI/SILC_PACKET_PADLEN
360 * #define SILC_PACKET_PADLEN ...
364 * Returns the length of the padding in the packet. This is used
365 * by various library routines to determine needed padding length.
369 #define SILC_PACKET_PADLEN(__packetlen, __blocklen) \
370 SILC_PACKET_DEFAULT_PADLEN - (__packetlen) % \
371 ((__blocklen) ? (__blocklen) : SILC_PACKET_DEFAULT_PADLEN)
374 /****d* silccore/SilcPacketAPI/SILC_PACKET_PADLEN_MAX
378 * #define SILC_PACKET_PADLEN_MAX ...
382 * Returns the length of the padding up to the maximum length, which
383 * is 128 butes. This is used by various library routines to determine
384 * needed padding length.
388 #define SILC_PACKET_PADLEN_MAX(__packetlen) \
389 SILC_PACKET_MAX_PADLEN - (__packetlen) % SILC_PACKET_MAX_PADLEN
394 /****f* silccore/SilcPacketAPI/silc_packet_send
398 * int silc_packet_send(SilcSocketConnection sock, bool force_send);
402 * Actually sends the packet. This flushes the connections outgoing data
403 * buffer. If data is sent directly to the network this returns the bytes
404 * written, if error occured this returns -1 and if the data could not
405 * be written directly to the network at this time this returns -2, in
406 * which case the data should be queued by the caller and sent at some
407 * later time. If `force_send' is TRUE this attempts to write the data
408 * directly to the network, if FALSE, this returns -2.
411 int silc_packet_send(SilcSocketConnection sock, bool force_send);
413 /****f* silccore/SilcPacketAPI/silc_packet_encrypt
417 * void silc_packet_encrypt(SilcCipher cipher, SilcHmac hmac,
418 * SilcBuffer buffer, SilcUInt32 len);
422 * Encrypts a packet. This also creates HMAC of the packet before
423 * encryption and adds the HMAC at the end of the buffer. This assumes
424 * that there is enough free space at the end of the buffer to add the
425 * computed HMAC. This is the normal way of encrypting packets, if some
426 * other process of HMAC computing and encryption is needed this function
430 void silc_packet_encrypt(SilcCipher cipher, SilcHmac hmac, SilcUInt32 sequence,
431 SilcBuffer buffer, SilcUInt32 len);
433 /****f* silccore/SilcPacketAPI/silc_packet_assemble
437 * void silc_packet_assemble(SilcPacketContext *ctx);
441 * Assembles a new packet to be ready for send out. The buffer sent as
442 * argument must include the data to be sent and it must not be encrypted.
443 * The packet also must have enough free space so that the SILC header
444 * and padding maybe added to the packet. The packet is encrypted after
445 * this function has returned.
447 * The buffer sent as argument should be something like following:
449 * --------------------------------------------
450 * | head | data | tail |
451 * --------------------------------------------
455 * So that the SILC header and 1 - 16 bytes of padding can fit to
456 * the buffer. After assembly the buffer might look like this:
458 * --------------------------------------------
460 * --------------------------------------------
462 * Start of assembled packet
464 * Packet construct is as follows (* = won't be encrypted):
466 * n bytes SILC Header
467 * 2 bytes Payload length (*)
470 * 2 bytes Source ID Length
471 * 2 bytes Destination ID Length
472 * 1 byte Source ID Type
474 * 1 byte Destination ID Type
475 * n bytes Destination ID
477 * 1 - 16 bytes Padding
479 * n bytes Data payload
481 * All fields in the packet will be authenticated by MAC. The MAC is
482 * not computed here, it must be computed separately before encrypting
486 void silc_packet_assemble(SilcPacketContext *ctx, SilcCipher cipher);
488 /****f* silccore/SilcPacketAPI/silc_packet_send_prepare
492 * void silc_packet_send_prepare(SilcSocketConnection sock,
493 * SilcUInt32 header_len,
495 * SilcUInt32 data_len);
499 * Prepare outgoing data buffer for packet sending. This moves the data
500 * area so that new packet may be added into it. If needed this allocates
501 * more space to the buffer. This handles directly the connection's
502 * outgoing buffer in SilcSocketConnection object.
505 void silc_packet_send_prepare(SilcSocketConnection sock,
506 SilcUInt32 header_len,
508 SilcUInt32 data_len);
510 /****f* silccore/SilcPacketAPI/silc_packet_receive
514 * int silc_packet_receive(SilcSocketConnection sock);
518 * Receives packet from network and reads the data into connection's
519 * incoming data buffer. If the data was read directly this returns the
520 * read bytes, if error occured this returns -1, if the data could not
521 * be read directly at this time this returns -2 in which case the data
522 * should be read again at some later time, or If EOF occured this returns
526 int silc_packet_receive(SilcSocketConnection sock);
528 /****f* silccore/SilcPacketAPI/silc_packet_receive_process
532 * bool silc_packet_receive_process(SilcSocketConnection sock,
533 * bool local_is_router,
534 * SilcCipher cipher, SilcHmac hmac,
535 * SilcPacketParserCallback parser,
536 * void *parser_context);
540 * Processes and decrypts the incoming data, and calls parser callback
541 * for each received packet that will handle the actual packet parsing.
542 * If more than one packet was received this calls the parser multiple
543 * times. The parser callback will get context SilcPacketParserContext
544 * that includes the packet and the `parser_context' sent to this
547 * The `local_is_router' indicates whether the caller is router server
548 * in which case the receiving process of a certain packet types may
549 * be special. Normal server and client must set it to FALSE. The
550 * SilcPacketParserContext will indicate also whether the received
551 * packet was normal or special packet.
554 bool silc_packet_receive_process(SilcSocketConnection sock,
555 bool local_is_router,
556 SilcCipher cipher, SilcHmac hmac,
558 SilcPacketParserCallback parser,
559 void *parser_context);
561 /****f* silccore/SilcPacketAPI/silc_packet_parse
565 * SilcPacketType silc_packet_parse(SilcPacketContext *ctx);
569 * Parses the packet. This is called when a whole packet is ready to be
570 * parsed. The buffer sent must be already decrypted before calling this
571 * function. The len argument must be the true length of the packet. This
572 * function returns the type of the packet. The data section of the
573 * buffer is parsed, not head or tail sections.
576 SilcPacketType silc_packet_parse(SilcPacketContext *ctx, SilcCipher cipher);
578 /****f* silccore/SilcPacketAPI/silc_packet_parse_special
582 * SilcPacketType silc_packet_parse_special(SilcPacketContext *ctx);
586 * Perform special SILC Packet header parsing. This is required to some
587 * packet types that have the data payload encrypted with different key
588 * than the header area plus padding of the packet. Hence, this parses
589 * the header in a way that it does not take the data area into account
590 * and parses the header and padding area only.
593 SilcPacketType silc_packet_parse_special(SilcPacketContext *ctx,
596 /****f* silccore/SilcPacketAPI/silc_packet_context_alloc
600 * SilcPacketContext *silc_packet_context_alloc();
604 * Allocates a packet context. Packet contexts are used when
605 * packets are assembled and parsed. The context is freed by the
606 * silc_packet_context_free function.
609 SilcPacketContext *silc_packet_context_alloc(void);
611 /****f* silccore/SilcPacketAPI/silc_packet_context_dup
615 * SilcPacketContext *silc_packet_context_dup(SilcPacketContext *ctx);
619 * Duplicates the packet context. It actually does not duplicate
620 * any data, instead a reference counter is increased.
623 SilcPacketContext *silc_packet_context_dup(SilcPacketContext *ctx);
625 /****f* silccore/SilcPacketAPI/silc_packet_context_free
629 * void silc_packet_context_free(SilcPacketContext *ctx);
633 * Frees the packet context. The context is actually freed when the
634 * reference counter hits zero.
637 void silc_packet_context_free(SilcPacketContext *ctx);