mdw@git.distorted.org.uk Git - tripe/blob - server/tripe.h

   1 /* -*-c-*-
   2  *
   3  * Main header file for TrIPE
   4  *
   5  * (c) 2001 Straylight/Edgeware
   6  */
   7
   8 /*----- Licensing notice --------------------------------------------------*
   9  *
  10  * This file is part of Trivial IP Encryption (TrIPE).
  11  *
  12  * TrIPE is free software; you can redistribute it and/or modify
  13  * it under the terms of the GNU General Public License as published by
  14  * the Free Software Foundation; either version 2 of the License, or
  15  * (at your option) any later version.
  16  *
  17  * TrIPE is distributed in the hope that it will be useful,
  18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20  * GNU General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU General Public License
  23  * along with TrIPE; if not, write to the Free Software Foundation,
  24  * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  25  */
  26
  27 #ifndef TRIPE_H
  28 #define TRIPE_H
  29
  30 #ifdef __cplusplus
  31   extern "C" {
  32 #endif
  33
  34 /*----- Header files ------------------------------------------------------*/
  35
  36 #include "config.h"
  37
  38 #include <assert.h>
  39 #include <ctype.h>
  40 #include <errno.h>
  41 #include <limits.h>
  42 #include <signal.h>
  43 #include <stdarg.h>
  44 #include <stddef.h>
  45 #include <stdio.h>
  46 #include <stdlib.h>
  47 #include <string.h>
  48 #include <time.h>
  49
  50 #include <sys/types.h>
  51 #include <sys/time.h>
  52 #include <unistd.h>
  53 #include <fcntl.h>
  54 #include <sys/stat.h>
  55
  56 #include <sys/socket.h>
  57 #include <sys/un.h>
  58 #include <netinet/in.h>
  59 #include <arpa/inet.h>
  60 #include <netdb.h>
  61
  62 #include <pwd.h>
  63 #include <grp.h>
  64
  65 #include <mLib/alloc.h>
  66 #include <mLib/arena.h>
  67 #include <mLib/base64.h>
  68 #include <mLib/bres.h>
  69 #include <mLib/daemonize.h>
  70 #include <mLib/dstr.h>
  71 #include <mLib/env.h>
  72 #include <mLib/fdflags.h>
  73 #include <mLib/fwatch.h>
  74 #include <mLib/hash.h>
  75 #include <mLib/macros.h>
  76 #include <mLib/mdwopt.h>
  77 #include <mLib/quis.h>
  78 #include <mLib/report.h>
  79 #include <mLib/sel.h>
  80 #include <mLib/selbuf.h>
  81 #include <mLib/sig.h>
  82 #include <mLib/str.h>
  83 #include <mLib/sub.h>
  84 #include <mLib/trace.h>
  85 #include <mLib/tv.h>
  86 #include <mLib/versioncmp.h>
  87
  88 #include <catacomb/buf.h>
  89
  90 #include <catacomb/gcipher.h>
  91 #include <catacomb/gmac.h>
  92 #include <catacomb/grand.h>
  93 #include <catacomb/key.h>
  94 #include <catacomb/paranoia.h>
  95
  96 #include <catacomb/noise.h>
  97 #include <catacomb/rand.h>
  98
  99 #include <catacomb/mp.h>
 100 #include <catacomb/mprand.h>
 101 #include <catacomb/dh.h>
 102 #include <catacomb/ec.h>
 103 #include <catacomb/ec-keys.h>
 104 #include <catacomb/group.h>
 105
 106 #include "protocol.h"
 107 #include "slip.h"
 108 #include "util.h"
 109
 110 #undef sun
 111
 112 /*----- Magic numbers -----------------------------------------------------*/
 113
 114 /* --- Trace flags --- */
 115
 116 #define T_TUNNEL 1u
 117 #define T_PEER 2u
 118 #define T_PACKET 4u
 119 #define T_ADMIN 8u
 120 #define T_CRYPTO 16u
 121 #define T_KEYSET 32u
 122 #define T_KEYEXCH 64u
 123 #define T_KEYMGMT 128u
 124 #define T_CHAL 256u
 125
 126 #define T_ALL 511u
 127
 128 /* --- Units --- */
 129
 130 #define SEC(n) (n##u)
 131 #define MIN(n) (n##u * 60u)
 132 #define MEG(n) (n##ul * 1024ul * 1024ul)
 133
 134 /* --- Other things --- */
 135
 136 #define PKBUFSZ 65536
 137
 138 /*----- Cipher selections -------------------------------------------------*/
 139
 140 typedef struct algswitch {
 141   const gccipher *c;                    /* Symmetric encryption scheme */
 142   const gccipher *mgf;                  /* Mask-generation function */
 143   const gchash *h;                      /* Hash function */
 144   const gcmac *m;                       /* Message authentication code */
 145   size_t hashsz;                        /* Hash output size */
 146   size_t tagsz;                         /* Length to truncate MAC tags */
 147   size_t expsz;                         /* Size of data to process */
 148   size_t cksz, mksz;                    /* Key lengths for @c@ and @m@ */
 149 } algswitch;
 150
 151 extern algswitch algs;
 152
 153 #define MAXHASHSZ 64                    /* Largest possible hash size */
 154
 155 #define HASH_STRING(h, s) GH_HASH((h), (s), sizeof(s))
 156
 157 /*----- Data structures ---------------------------------------------------*/
 158
 159 /* --- Socket addresses --- *
 160  *
 161  * A magic union of supported socket addresses.
 162  */
 163
 164 typedef union addr {
 165   struct sockaddr sa;
 166   struct sockaddr_in sin;
 167 } addr;
 168
 169 /* --- Mapping keyed on addresses --- */
 170
 171 typedef struct addrmap {
 172   hash_table t;
 173   size_t load;
 174 } addrmap;
 175
 176 typedef struct addrmap_base {
 177   hash_base b;
 178   addr a;
 179 } addrmap_base;
 180
 181 /* --- Sequence number checking --- */
 182
 183 typedef struct seqwin {
 184   uint32 seq;                           /* First acceptable input sequence */
 185   uint32 win;                           /* Window of acceptable numbers */
 186 } seqwin;
 187
 188 #define SEQ_WINSZ 32                    /* Bits in sequence number window */
 189
 190 /* --- A symmetric keyset --- *
 191  *
 192  * A keyset contains a set of symmetric keys for encrypting and decrypting
 193  * packets.  Keysets are stored in a list, sorted in reverse order of
 194  * creation, so that the most recent keyset (the one most likely to be used)
 195  * is first.
 196  *
 197  * Each keyset has a time limit and a data limit.  The keyset is destroyed
 198  * when either it has existed for too long, or it has been used to encrypt
 199  * too much data.  New key exchanges are triggered when keys are close to
 200  * expiry.
 201  */
 202
 203 typedef struct keyset {
 204   struct keyset *next;                  /* Next active keyset in the list */
 205   unsigned ref;                         /* Reference count for keyset */
 206   struct peer *p;                       /* Pointer to peer structure */
 207   time_t t_exp;                         /* Expiry time for this keyset */
 208   unsigned long sz_exp, sz_regen;       /* Data limits for the keyset */
 209   T( unsigned seq; )                    /* Sequence number for tracing */
 210   unsigned f;                           /* Various useful flags */
 211   gcipher *cin, *cout;                  /* Keyset ciphers for encryption */
 212   size_t tagsz;                         /* Length to truncate MAC tags */
 213   gmac *min, *mout;                     /* Keyset MACs for integrity */
 214   uint32 oseq;                          /* Outbound sequence number */
 215   seqwin iseq;                          /* Inbound sequence number */
 216 } keyset;
 217
 218 #define KSF_LISTEN 1u                   /* Don't encrypt packets yet */
 219 #define KSF_LINK 2u                     /* Key is in a linked list */
 220
 221 #define KSERR_REGEN -1                  /* Regenerate keys */
 222 #define KSERR_NOKEYS -2                 /* No keys left */
 223 #define KSERR_DECRYPT -3                /* Unable to decrypt message */
 224
 225 /* --- Key exchange --- *
 226  *
 227  * TrIPE uses the Wrestlers Protocol for its key exchange.  The Wrestlers
 228  * Protocol has a number of desirable features (e.g., perfect forward
 229  * secrecy, and zero-knowledge authentication) which make it attractive for
 230  * use in TrIPE.  The Wrestlers Protocol was designed by Mark Wooding and
 231  * Clive Jones.
 232  */
 233
 234 #define KX_NCHAL 16u
 235
 236 typedef struct kxchal {
 237   struct keyexch *kx;                   /* Pointer back to key exchange */
 238   ge *c;                                /* Responder's challenge */
 239   ge *r;                                /* My reply to the challenge */
 240   keyset *ks;                           /* Pointer to temporary keyset */
 241   unsigned f;                           /* Various useful flags */
 242   sel_timer t;                          /* Response timer for challenge */
 243   octet hc[MAXHASHSZ];                  /* Hash of his challenge */
 244   octet ck[MAXHASHSZ];                  /* His magical check value */
 245   octet hswrq_in[MAXHASHSZ];            /* Inbound switch request message */
 246   octet hswok_in[MAXHASHSZ];            /* Inbound switch confirmation */
 247   octet hswrq_out[MAXHASHSZ];           /* Outbound switch request message */
 248   octet hswok_out[MAXHASHSZ];           /* Outbound switch confirmation */
 249 } kxchal;
 250
 251 typedef struct keyexch {
 252   struct peer *p;                       /* Pointer back to the peer */
 253   keyset **ks;                          /* Peer's list of keysets */
 254   unsigned f;                           /* Various useful flags */
 255   unsigned s;                           /* Current state in exchange */
 256   sel_timer t;                          /* Timer for next exchange */
 257   ge *kpub;                             /* Peer's public key */
 258   time_t texp_kpub;                     /* Expiry time for public key */
 259   mp *alpha;                            /* My temporary secret */
 260   ge *c;                                /* My challenge */
 261   ge *rx;                               /* The expected response */
 262   unsigned nr;                          /* Number of extant responses */
 263   time_t t_valid;                       /* When this exchange goes bad */
 264   octet hc[MAXHASHSZ];                  /* Hash of my challenge */
 265   kxchal *r[KX_NCHAL];                  /* Array of challenges */
 266 } keyexch;
 267
 268 #define KXF_TIMER 1u                    /* Waiting for a timer to go off */
 269 #define KXF_DEAD 2u                     /* The key-exchanger isn't up */
 270 #define KXF_PUBKEY 4u                   /* Key exchanger has a public key */
 271 #define KXF_CORK 8u                     /* Don't send anything yet */
 272
 273 enum {
 274   KXS_DEAD,                             /* Uninitialized state (magical) */
 275   KXS_CHAL,                             /* Main answer-challenges state */
 276   KXS_COMMIT,                           /* Committed: send switch request */
 277   KXS_SWITCH                            /* Switched: send confirmation */
 278 };
 279
 280 /* --- Tunnel structure --- *
 281  *
 282  * Used to maintain system-specific information about the tunnel interface.
 283  */
 284
 285 typedef struct tunnel tunnel;
 286 struct peer;
 287
 288 typedef struct tunnel_ops {
 289   const char *name;                     /* Name of this tunnel driver */
 290   void (*init)(void);                   /* Initializes the system */
 291   int (*open)(char **/*ifn*/);          /* Open tunnel and report ifname */
 292   tunnel *(*create)(struct peer */*p*/, int /*fd*/, char **/*ifn*/);
 293                                         /* Initializes a new tunnel */
 294   void (*setifname)(tunnel */*t*/, const char */*ifn*/);
 295                                         /*  Notifies ifname change */
 296   void (*inject)(tunnel */*t*/, buf */*b*/); /* Sends packet through if */
 297   void (*destroy)(tunnel */*t*/);       /* Destroys a tunnel */
 298 } tunnel_ops;
 299
 300 #ifndef TUN_INTERNALS
 301 struct tunnel { const tunnel_ops *ops; };
 302 #endif
 303
 304 /* --- Peer statistics --- *
 305  *
 306  * Contains various interesting and not-so-interesting statistics about a
 307  * peer.  This is updated by various parts of the code.  The format of the
 308  * structure isn't considered private, and @p_stats@ returns a pointer to the
 309  * statistics block for a given peer.
 310  */
 311
 312 typedef struct stats {
 313   unsigned long sz_in, sz_out;          /* Size of all data in and out */
 314   unsigned long sz_kxin, sz_kxout;      /* Size of key exchange messages */
 315   unsigned long sz_ipin, sz_ipout;      /* Size of encapsulated IP packets */
 316   time_t t_start, t_last, t_kx;         /* Time peer created, last pk, kx */
 317   unsigned long n_reject;               /* Number of rejected packets */
 318   unsigned long n_in, n_out;            /* Number of packets in and out */
 319   unsigned long n_kxin, n_kxout;        /* Number of key exchange packets */
 320   unsigned long n_ipin, n_ipout;        /* Number of encrypted packets */
 321 } stats;
 322
 323 /* --- Peer structure --- *
 324  *
 325  * The main structure which glues everything else together.
 326  */
 327
 328 typedef struct peerspec {
 329   char *name;                           /* Peer's name */
 330   const tunnel_ops *tops;               /* Tunnel operations */
 331   unsigned long t_ka;                   /* Keep alive interval */
 332   addr sa;                              /* Socket address to speak to */
 333   size_t sasz;                          /* Socket address size */
 334   unsigned kxf;                         /* Key exchange flags to set */
 335 } peerspec;
 336
 337 typedef struct peer_byname {
 338   sym_base _b;
 339   struct peer *p;
 340 } peer_byname;
 341
 342 typedef struct peer_byaddr {
 343   addrmap_base _b;
 344   struct peer *p;
 345 } peer_byaddr;
 346
 347 typedef struct peer {
 348   peer_byname *byname;                  /* Lookup-by-name block */
 349   peer_byaddr *byaddr;                  /* Lookup-by-address block */
 350   struct ping *pings;                   /* Pings we're waiting for */
 351   peerspec spec;                        /* Specifications for this peer */
 352   tunnel *t;                            /* Tunnel for local packets */
 353   char *ifname;                         /* Interface name for tunnel */
 354   keyset *ks;                           /* List head for keysets */
 355   buf b;                                /* Buffer for sending packets */
 356   stats st;                             /* Statistics */
 357   keyexch kx;                           /* Key exchange protocol block */
 358   sel_timer tka;                        /* Timer for keepalives */
 359 } peer;
 360
 361 typedef struct peer_iter { sym_iter i; } peer_iter;
 362
 363 typedef struct ping {
 364   struct ping *next, *prev;             /* Links to next and previous */
 365   peer *p;                              /* Peer so we can free it */
 366   unsigned msg;                         /* Kind of response expected */
 367   uint32 id;                            /* Id so we can recognize response */
 368   octet magic[32];                      /* Some random data */
 369   sel_timer t;                          /* Timeout for ping */
 370   void (*func)(int /*rc*/, void */*arg*/); /* Function to call when done */
 371   void *arg;                            /* Argument for callback */
 372 } ping;
 373
 374 enum {
 375   PING_NONOTIFY = -1,
 376   PING_OK = 0,
 377   PING_TIMEOUT,
 378   PING_PEERDIED,
 379   PING_MAX
 380 };
 381
 382 /* --- Admin structure --- */
 383
 384 #define OBUFSZ 16384u
 385
 386 typedef struct obuf {
 387   struct obuf *next;                    /* Next buffer in list */
 388   char *p_in, *p_out;                   /* Pointers into the buffer */
 389   char buf[OBUFSZ];                     /* The actual buffer */
 390 } obuf;
 391
 392 typedef struct oqueue {
 393   obuf *hd, *tl;                        /* Head and tail pointers */
 394 } oqueue;
 395
 396 struct admin;
 397
 398 typedef struct admin_bgop {
 399   struct admin_bgop *next, *prev;       /* Links to next and previous */
 400   struct admin *a;                      /* Owner job */
 401   char *tag;                            /* Tag string for messages */
 402   void (*cancel)(struct admin_bgop *);  /* Destructor function */
 403 } admin_bgop;
 404
 405 typedef struct admin_resop {
 406   admin_bgop bg;                        /* Background operation header */
 407   char *addr;                           /* Hostname to be resolved */
 408   bres_client r;                        /* Background resolver task */
 409   sel_timer t;                          /* Timer for resolver */
 410   addr sa;                              /* Socket address */
 411   size_t sasz;                          /* Socket address size */
 412   void (*func)(struct admin_resop *, int); /* Handler */
 413 } admin_resop;
 414
 415 enum { ARES_OK, ARES_FAIL };
 416
 417 typedef struct admin_addop {
 418   admin_resop r;                        /* Name resolution header */
 419   peerspec peer;                        /* Peer pending creation */
 420 } admin_addop;
 421
 422 typedef struct admin_greetop {
 423   admin_resop r;                        /* Name resolution header */
 424   void *c;                              /* Challenge block */
 425   size_t sz;                            /* Length of challenge */
 426 } admin_greetop;
 427
 428 typedef struct admin_pingop {
 429   admin_bgop bg;                        /* Background operation header */
 430   ping ping;                            /* Ping pending response */
 431   struct timeval pingtime;              /* Time last ping was sent */
 432 } admin_pingop;
 433
 434 typedef struct admin_service {
 435   sym_base _b;                          /* Hash table base structure */
 436   char *version;                        /* The provided version */
 437   struct admin *prov;                   /* Which client provides me */
 438   struct admin_service *next, *prev;    /* Client's list of services */
 439 } admin_service;
 440
 441 typedef struct admin_svcop {
 442   admin_bgop bg;                        /* Background operation header */
 443   struct admin *prov;                   /* Client servicing this job */
 444   unsigned index;                       /* This job's index */
 445   struct admin_svcop *next, *prev;      /* Links for provider's jobs */
 446 } admin_svcop;
 447
 448 typedef struct admin_jobentry {
 449   unsigned short seq;                   /* Zero if unused */
 450   union {
 451     admin_svcop *op;                    /* Operation, if slot in use, ... */
 452     uint32 next;                        /* ... or index of next free slot */
 453   } u;
 454 } admin_jobentry;
 455
 456 typedef struct admin_jobtable {
 457   uint32 n, sz;                         /* Used slots and table size */
 458   admin_svcop *active;                  /* List of active jobs */
 459   uint32 free;                          /* Index of first free slot */
 460   admin_jobentry *v;                    /* And the big array of entries */
 461 } admin_jobtable;
 462
 463 typedef struct admin {
 464   struct admin *next, *prev;            /* Links to next and previous */
 465   unsigned f;                           /* Various useful flags */
 466   unsigned ref;                         /* Reference counter */
 467 #ifndef NTRACE
 468   unsigned seq;                         /* Sequence number for tracing */
 469 #endif
 470   oqueue out;                           /* Output buffer list */
 471   oqueue delay;                         /* Delayed output buffer list */
 472   admin_bgop *bg;                       /* Backgrounded operations */
 473   admin_service *svcs;                  /* Which services I provide */
 474   admin_jobtable j;                     /* Table of outstanding jobs */
 475   selbuf b;                             /* Line buffer for commands */
 476   sel_file w;                           /* Selector for write buffering */
 477 } admin;
 478
 479 #define AF_DEAD 1u                      /* Destroy this admin block */
 480 #define AF_CLOSE 2u                     /* Client closed connection */
 481 #define AF_NOTE 4u                      /* Catch notifications */
 482 #define AF_WARN 8u                      /* Catch warning messages */
 483 #ifndef NTRACE
 484   #define AF_TRACE 16u                  /* Catch tracing */
 485 #endif
 486 #define AF_FOREGROUND 32u               /* Quit server when client closes */
 487
 488 #ifndef NTRACE
 489 #  define AF_ALLMSGS (AF_NOTE | AF_TRACE | AF_WARN)
 490 #else
 491 #  define AF_ALLMSGS (AF_NOTE | AF_WARN)
 492 #endif
 493
 494 /*----- Global variables --------------------------------------------------*/
 495
 496 extern sel_state sel;                   /* Global I/O event state */
 497 extern group *gg;                       /* The group we work in */
 498 extern size_t indexsz;                  /* Size of exponent for the group */
 499 extern mp *kpriv;                       /* Our private key */
 500 extern ge *kpub;                        /* Our public key */
 501 extern octet buf_i[PKBUFSZ], buf_o[PKBUFSZ], buf_t[PKBUFSZ], buf_u[PKBUFSZ];
 502 extern const tunnel_ops *tunnels[];     /* Table of tunnels (0-term) */
 503 extern const tunnel_ops *tun_default;   /* Default tunnel to use */
 504
 505 #ifndef NTRACE
 506 extern const trace_opt tr_opts[];       /* Trace options array */
 507 extern unsigned tr_flags;               /* Trace options flags */
 508 #endif
 509
 510 /*----- Other macros ------------------------------------------------------*/
 511
 512 #define TIMER noise_timer(RAND_GLOBAL)
 513
 514 /*----- Key management ----------------------------------------------------*/
 515
 516 /* --- @km_reload@ --- *
 517  *
 518  * Arguments:   ---
 519  *
 520  * Returns:     Zero if OK, nonzero to force reloading of keys.
 521  *
 522  * Use:         Checks the keyrings to see if they need reloading.
 523  */
 524
 525 extern int km_reload(void);
 526
 527 /* --- @km_init@ --- *
 528  *
 529  * Arguments:   @const char *kr_priv@ = private keyring file
 530  *              @const char *kr_pub@ = public keyring file
 531  *              @const char *tag@ = tag to load
 532  *
 533  * Returns:     ---
 534  *
 535  * Use:         Initializes, and loads the private key.
 536  */
 537
 538 extern void km_init(const char */*kr_priv*/, const char */*kr_pub*/,
 539                     const char */*tag*/);
 540
 541 /* --- @km_getpubkey@ --- *
 542  *
 543  * Arguments:   @const char *tag@ = public key tag to load
 544  *              @ge *kpub@ = where to put the public key
 545  *              @time_t *t_exp@ = where to put the expiry time
 546  *
 547  * Returns:     Zero if OK, nonzero if it failed.
 548  *
 549  * Use:         Fetches a public key from the keyring.
 550  */
 551
 552 extern int km_getpubkey(const char */*tag*/, ge */*kpub*/,
 553                         time_t */*t_exp*/);
 554
 555 /*----- Key exchange ------------------------------------------------------*/
 556
 557 /* --- @kx_start@ --- *
 558  *
 559  * Arguments:   @keyexch *kx@ = pointer to key exchange context
 560  *              @int forcep@ = nonzero to ignore the quiet timer
 561  *
 562  * Returns:     ---
 563  *
 564  * Use:         Stimulates a key exchange.  If a key exchage is in progress,
 565  *              a new challenge is sent (unless the quiet timer forbids
 566  *              this); if no exchange is in progress, one is commenced.
 567  */
 568
 569 extern void kx_start(keyexch */*kx*/, int /*forcep*/);
 570
 571 /* --- @kx_message@ --- *
 572  *
 573  * Arguments:   @keyexch *kx@ = pointer to key exchange context
 574  *              @unsigned msg@ = the message code
 575  *              @buf *b@ = pointer to buffer containing the packet
 576  *
 577  * Returns:     ---
 578  *
 579  * Use:         Reads a packet containing key exchange messages and handles
 580  *              it.
 581  */
 582
 583 extern void kx_message(keyexch */*kx*/, unsigned /*msg*/, buf */*b*/);
 584
 585 /* --- @kx_free@ --- *
 586  *
 587  * Arguments:   @keyexch *kx@ = pointer to key exchange context
 588  *
 589  * Returns:     ---
 590  *
 591  * Use:         Frees everything in a key exchange context.
 592  */
 593
 594 extern void kx_free(keyexch */*kx*/);
 595
 596 /* --- @kx_newkeys@ --- *
 597  *
 598  * Arguments:   @keyexch *kx@ = pointer to key exchange context
 599  *
 600  * Returns:     ---
 601  *
 602  * Use:         Informs the key exchange module that its keys may have
 603  *              changed.  If fetching the new keys fails, the peer will be
 604  *              destroyed, we log messages and struggle along with the old
 605  *              keys.
 606  */
 607
 608 extern void kx_newkeys(keyexch */*kx*/);
 609
 610 /* --- @kx_init@ --- *
 611  *
 612  * Arguments:   @keyexch *kx@ = pointer to key exchange context
 613  *              @peer *p@ = pointer to peer context
 614  *              @keyset **ks@ = pointer to keyset list
 615  *              @unsigned f@ = various useful flags
 616  *
 617  * Returns:     Zero if OK, nonzero if it failed.
 618  *
 619  * Use:         Initializes a key exchange module.  The module currently
 620  *              contains no keys, and will attempt to initiate a key
 621  *              exchange.
 622  */
 623
 624 extern int kx_init(keyexch */*kx*/, peer */*p*/,
 625                    keyset **/*ks*/, unsigned /*f*/);
 626
 627 /*----- Keysets and symmetric cryptography --------------------------------*/
 628
 629 /* --- @ks_drop@ --- *
 630  *
 631  * Arguments:   @keyset *ks@ = pointer to a keyset
 632  *
 633  * Returns:     ---
 634  *
 635  * Use:         Decrements a keyset's reference counter.  If the counter hits
 636  *              zero, the keyset is freed.
 637  */
 638
 639 extern void ks_drop(keyset */*ks*/);
 640
 641 /* --- @ks_gen@ --- *
 642  *
 643  * Arguments:   @const void *k@ = pointer to key material
 644  *              @size_t x, y, z@ = offsets into key material (see below)
 645  *              @peer *p@ = pointer to peer information
 646  *
 647  * Returns:     A pointer to the new keyset.
 648  *
 649  * Use:         Derives a new keyset from the given key material.  The
 650  *              offsets @x@, @y@ and @z@ separate the key material into three
 651  *              parts.  Between the @k@ and @k + x@ is `my' contribution to
 652  *              the key material; between @k + x@ and @k + y@ is `your'
 653  *              contribution; and between @k + y@ and @k + z@ is a shared
 654  *              value we made together.  These are used to construct two
 655  *              pairs of symmetric keys.  Each pair consists of an encryption
 656  *              key and a message authentication key.  One pair is used for
 657  *              outgoing messages, the other for incoming messages.
 658  *
 659  *              The new key is marked so that it won't be selected for output
 660  *              by @ksl_encrypt@.  You can still encrypt data with it by
 661  *              calling @ks_encrypt@ directly.
 662  */
 663
 664 extern keyset *ks_gen(const void */*k*/,
 665                       size_t /*x*/, size_t /*y*/, size_t /*z*/,
 666                       peer */*p*/);
 667
 668 /* --- @ks_tregen@ --- *
 669  *
 670  * Arguments:   @keyset *ks@ = pointer to a keyset
 671  *
 672  * Returns:     The time at which moves ought to be made to replace this key.
 673  */
 674
 675 extern time_t ks_tregen(keyset */*ks*/);
 676
 677 /* --- @ks_activate@ --- *
 678  *
 679  * Arguments:   @keyset *ks@ = pointer to a keyset
 680  *
 681  * Returns:     ---
 682  *
 683  * Use:         Activates a keyset, so that it can be used for encrypting
 684  *              outgoing messages.
 685  */
 686
 687 extern void ks_activate(keyset */*ks*/);
 688
 689 /* --- @ks_encrypt@ --- *
 690  *
 691  * Arguments:   @keyset *ks@ = pointer to a keyset
 692  *              @unsigned ty@ = message type
 693  *              @buf *b@ = pointer to input buffer
 694  *              @buf *bb@ = pointer to output buffer
 695  *
 696  * Returns:     Zero if successful; @KSERR_REGEN@ if we should negotiate a
 697  *              new key; @KSERR_NOKEYS@ if the key is not usable.  Also
 698  *              returns zero if there was insufficient buffer (but the output
 699  *              buffer is broken in this case).
 700  *
 701  * Use:         Encrypts a block of data using the key.  Note that the `key
 702  *              ought to be replaced' notification is only ever given once
 703  *              for each key.  Also note that this call forces a keyset to be
 704  *              used even if it's marked as not for data output.
 705  */
 706
 707 extern int ks_encrypt(keyset */*ks*/, unsigned /*ty*/,
 708                       buf */*b*/, buf */*bb*/);
 709
 710 /* --- @ks_decrypt@ --- *
 711  *
 712  * Arguments:   @keyset *ks@ = pointer to a keyset
 713  *              @unsigned ty@ = expected type code
 714  *              @buf *b@ = pointer to an input buffer
 715  *              @buf *bb@ = pointer to an output buffer
 716  *
 717  * Returns:     Zero on success; @KSERR_DECRYPT@ on failure.  Also returns
 718  *              zero if there was insufficient buffer (but the output buffer
 719  *              is broken in this case).
 720  *
 721  * Use:         Attempts to decrypt a message using a given key.  Note that
 722  *              requesting decryption with a key directly won't clear a
 723  *              marking that it's not for encryption.
 724  */
 725
 726 extern int ks_decrypt(keyset */*ks*/, unsigned /*ty*/,
 727                       buf */*b*/, buf */*bb*/);
 728
 729 /* --- @ksl_free@ --- *
 730  *
 731  * Arguments:   @keyset **ksroot@ = pointer to keyset list head
 732  *
 733  * Returns:     ---
 734  *
 735  * Use:         Frees (releases references to) all of the keys in a keyset.
 736  */
 737
 738 extern void ksl_free(keyset **/*ksroot*/);
 739
 740 /* --- @ksl_link@ --- *
 741  *
 742  * Arguments:   @keyset **ksroot@ = pointer to keyset list head
 743  *              @keyset *ks@ = pointer to a keyset
 744  *
 745  * Returns:     ---
 746  *
 747  * Use:         Links a keyset into a list.  A keyset can only be on one list
 748  *              at a time.  Bad things happen otherwise.
 749  */
 750
 751 extern void ksl_link(keyset **/*ksroot*/, keyset */*ks*/);
 752
 753 /* --- @ksl_prune@ --- *
 754  *
 755  * Arguments:   @keyset **ksroot@ = pointer to keyset list head
 756  *
 757  * Returns:     ---
 758  *
 759  * Use:         Prunes the keyset list by removing keys which mustn't be used
 760  *              any more.
 761  */
 762
 763 extern void ksl_prune(keyset **/*ksroot*/);
 764
 765 /* --- @ksl_encrypt@ --- *
 766  *
 767  * Arguments:   @keyset **ksroot@ = pointer to keyset list head
 768  *              @unsigned ty@ = message type
 769  *              @buf *b@ = pointer to input buffer
 770  *              @buf *bb@ = pointer to output buffer
 771  *
 772  * Returns:     Zero if successful; @KSERR_REGEN@ if it's time to negotiate a
 773  *              new key; @KSERR_NOKEYS@ if there are no suitable keys
 774  *              available.  Also returns zero if there was insufficient
 775  *              buffer space (but the output buffer is broken in this case).
 776  *
 777  * Use:         Encrypts a packet.
 778  */
 779
 780 extern int ksl_encrypt(keyset **/*ksroot*/, unsigned /*ty*/,
 781                        buf */*b*/, buf */*bb*/);
 782
 783 /* --- @ksl_decrypt@ --- *
 784  *
 785  * Arguments:   @keyset **ksroot@ = pointer to keyset list head
 786  *              @unsigned ty@ = expected type code
 787  *              @buf *b@ = pointer to input buffer
 788  *              @buf *bb@ = pointer to output buffer
 789  *
 790  * Returns:     Zero on success; @KSERR_DECRYPT@ on failure.  Also returns
 791  *              zero if there was insufficient buffer (but the output buffer
 792  *              is broken in this case).
 793  *
 794  * Use:         Decrypts a packet.
 795  */
 796
 797 extern int ksl_decrypt(keyset **/*ksroot*/, unsigned /*ty*/,
 798                        buf */*b*/, buf */*bb*/);
 799
 800 /*----- Challenges --------------------------------------------------------*/
 801
 802 /* --- @c_new@ --- *
 803  *
 804  * Arguments:   @buf *b@ = where to put the challenge
 805  *
 806  * Returns:     Zero if OK, nonzero on error.
 807  *
 808  * Use:         Issues a new challenge.
 809  */
 810
 811 extern int c_new(buf */*b*/);
 812
 813 /* --- @c_check@ --- *
 814  *
 815  * Arguments:   @buf *b@ = where to find the challenge
 816  *
 817  * Returns:     Zero if OK, nonzero if it didn't work.
 818  *
 819  * Use:         Checks a challenge.  On failure, the buffer is broken.
 820  */
 821
 822 extern int c_check(buf */*b*/);
 823
 824 /*----- Administration interface ------------------------------------------*/
 825
 826 #define A_END ((char *)0)
 827
 828 /* --- @a_warn@ --- *
 829  *
 830  * Arguments:   @const char *fmt@ = pointer to format string
 831  *              @...@ = other arguments
 832  *
 833  * Returns:     ---
 834  *
 835  * Use:         Informs all admin connections of a warning.
 836  */
 837
 838 extern void a_warn(const char */*fmt*/, ...);
 839
 840 /* --- @a_notify@ --- *
 841  *
 842  * Arguments:   @const char *fmt@ = pointer to format string
 843  *              @...@ = other arguments
 844  *
 845  * Returns:     ---
 846  *
 847  * Use:         Sends a notification to interested admin connections.
 848  */
 849
 850 extern void a_notify(const char */*fmt*/, ...);
 851
 852 /* --- @a_create@ --- *
 853  *
 854  * Arguments:   @int fd_in, fd_out@ = file descriptors to use
 855  *              @unsigned f@ = initial flags to set
 856  *
 857  * Returns:     ---
 858  *
 859  * Use:         Creates a new admin connection.
 860  */
 861
 862 extern void a_create(int /*fd_in*/, int /*fd_out*/, unsigned /*f*/);
 863
 864 /* --- @a_quit@ --- *
 865  *
 866  * Arguments:   ---
 867  *
 868  * Returns:     ---
 869  *
 870  * Use:         Shuts things down nicely.
 871  */
 872
 873 extern void a_quit(void);
 874
 875 /* --- @a_preselect@ --- *
 876  *
 877  * Arguments:   ---
 878  *
 879  * Returns:     ---
 880  *
 881  * Use:         Informs the admin module that we're about to select again,
 882  *              and that it should do cleanup things it has delayed until a
 883  *              `safe' time.
 884  */
 885
 886 extern void a_preselect(void);
 887
 888 /* --- @a_daemon@ --- *
 889  *
 890  * Arguments:   ---
 891  *
 892  * Returns:     ---
 893  *
 894  * Use:         Informs the admin module that it's a daemon.
 895  */
 896
 897 extern void a_daemon(void);
 898
 899 /* --- @a_init@ --- *
 900  *
 901  * Arguments:   @const char *sock@ = socket name to create
 902  *              @uid_t u@ = user to own the socket
 903  *              @gid_t g@ = group to own the socket
 904  *
 905  * Returns:     ---
 906  *
 907  * Use:         Creates the admin listening socket.
 908  */
 909
 910 extern void a_init(const char */*sock*/, uid_t /*u*/, gid_t /*g*/);
 911
 912 /*----- Mapping with addresses as keys ------------------------------------*/
 913
 914 /* --- @am_create@ --- *
 915  *
 916  * Arguments:   @addrmap *m@ = pointer to map
 917  *
 918  * Returns:     ---
 919  *
 920  * Use:         Create an address map, properly set up.
 921  */
 922
 923 extern void am_create(addrmap */*m*/);
 924
 925 /* --- @am_destroy@ --- *
 926  *
 927  * Arguments:   @addrmap *m@ = pointer to map
 928  *
 929  * Returns:     ---
 930  *
 931  * Use:         Destroy an address map, throwing away all the entries.
 932  */
 933
 934 extern void am_destroy(addrmap */*m*/);
 935
 936 /* --- @am_find@ --- *
 937  *
 938  * Arguments:   @addrmap *m@ = pointer to map
 939  *              @const addr *a@ = address to look up
 940  *              @size_t sz@ = size of block to allocate
 941  *              @unsigned *f@ = where to store flags
 942  *
 943  * Returns:     Pointer to found item, or null.
 944  *
 945  * Use:         Finds a record with the given IP address, set @*f@ nonzero
 946  *              and returns it.  If @sz@ is zero, and no match was found,
 947  *              return null; otherwise allocate a new block of @sz@ bytes,
 948  *              clear @*f@ to zero and return the block pointer.
 949  */
 950
 951 extern void *am_find(addrmap */*m*/, const addr */*a*/,
 952                      size_t /*sz*/, unsigned */*f*/);
 953
 954 /* --- @am_remove@ --- *
 955  *
 956  * Arguments:   @addrmap *m@ = pointer to map
 957  *              @void *i@ = pointer to the item
 958  *
 959  * Returns:     ---
 960  *
 961  * Use:         Removes an item from the map.
 962  */
 963
 964 extern void am_remove(addrmap */*m*/, void */*i*/);
 965
 966 /*----- Peer management ---------------------------------------------------*/
 967
 968 /* --- @p_txstart@ --- *
 969  *
 970  * Arguments:   @peer *p@ = pointer to peer block
 971  *              @unsigned msg@ = message type code
 972  *
 973  * Returns:     A pointer to a buffer to write to.
 974  *
 975  * Use:         Starts sending to a peer.  Only one send can happen at a
 976  *              time.
 977  */
 978
 979 extern buf *p_txstart(peer */*p*/, unsigned /*msg*/);
 980
 981 /* --- @p_txend@ --- *
 982  *
 983  * Arguments:   @peer *p@ = pointer to peer block
 984  *
 985  * Returns:     ---
 986  *
 987  * Use:         Sends a packet to the peer.
 988  */
 989
 990 extern void p_txend(peer */*p*/);
 991
 992 /* --- @p_pingsend@ --- *
 993  *
 994  * Arguments:   @peer *p@ = destination peer
 995  *              @ping *pg@ = structure to fill in
 996  *              @unsigned type@ = message type
 997  *              @unsigned long timeout@ = how long to wait before giving up
 998  *              @void (*func)(int, void *)@ = callback function
 999  *              @void *arg@ = argument for callback
1000  *
1001  * Returns:     Zero if successful, nonzero if it failed.
1002  *
1003  * Use:         Sends a ping to a peer.  Call @func@ with a nonzero argument
1004  *              if we get an answer within the timeout, or zero if no answer.
1005  */
1006
1007 extern int p_pingsend(peer */*p*/, ping */*pg*/, unsigned /*type*/,
1008                       unsigned long /*timeout*/,
1009                       void (*/*func*/)(int, void *), void */*arg*/);
1010
1011 /* --- @p_pingdone@ --- *
1012  *
1013  * Arguments:   @ping *p@ = ping structure
1014  *              @int rc@ = return code to pass on
1015  *
1016  * Returns:     ---
1017  *
1018  * Use:         Disposes of a ping structure, maybe sending a notification.
1019  */
1020
1021 extern void p_pingdone(ping */*p*/, int /*rc*/);
1022
1023 /* --- @p_greet@ --- *
1024  *
1025  * Arguments:   @peer *p@ = peer to send to
1026  *              @const void *c@ = pointer to challenge
1027  *              @size_t sz@ = size of challenge
1028  *
1029  * Returns:     ---
1030  *
1031  * Use:         Sends a greeting packet.
1032  */
1033
1034 extern void p_greet(peer */*p*/, const void */*c*/, size_t /*sz*/);
1035
1036 /* --- @p_tun@ --- *
1037  *
1038  * Arguments:   @peer *p@ = pointer to peer block
1039  *              @buf *b@ = buffer containing incoming packet
1040  *
1041  * Returns:     ---
1042  *
1043  * Use:         Handles a packet which needs to be sent to a peer.
1044  */
1045
1046 extern void p_tun(peer */*p*/, buf */*b*/);
1047
1048 /* --- @p_keyreload@ --- *
1049  *
1050  * Arguments:   ---
1051  *
1052  * Returns:     ---
1053  *
1054  * Use:         Forces a check of the daemon's keyring files.
1055  */
1056
1057 extern void p_keyreload(void);
1058
1059 /* --- @p_interval@ --- *
1060  *
1061  * Arguments:   ---
1062  *
1063  * Returns:     ---
1064  *
1065  * Use:         Called periodically to do tidying.
1066  */
1067
1068 extern void p_interval(void);
1069
1070 /* --- @p_stats@ --- *
1071  *
1072  * Arguments:   @peer *p@ = pointer to a peer block
1073  *
1074  * Returns:     A pointer to the peer's statistics.
1075  */
1076
1077 extern stats *p_stats(peer */*p*/);
1078
1079 /* --- @p_ifname@ --- *
1080  *
1081  * Arguments:   @peer *p@ = pointer to a peer block
1082  *
1083  * Returns:     A pointer to the peer's interface name.
1084  */
1085
1086 extern const char *p_ifname(peer */*p*/);
1087
1088 /* --- @p_setifname@ --- *
1089  *
1090  * Arguments:   @peer *p@ = pointer to a peer block
1091  *              @const char *name@ = pointer to the new name
1092  *
1093  * Returns:     ---
1094  *
1095  * Use:         Changes the name held for a peer's interface.
1096  */
1097
1098 extern void p_setifname(peer */*p*/, const char */*name*/);
1099
1100 /* --- @p_addr@ --- *
1101  *
1102  * Arguments:   @peer *p@ = pointer to a peer block
1103  *
1104  * Returns:     A pointer to the peer's address.
1105  */
1106
1107 extern const addr *p_addr(peer */*p*/);
1108
1109 /* --- @p_init@ --- *
1110  *
1111  * Arguments:   @struct in_addr addr@ = address to bind to
1112  *              @unsigned port@ = port number to listen to
1113  *
1114  * Returns:     ---
1115  *
1116  * Use:         Initializes the peer system; creates the socket.
1117  */
1118
1119 extern void p_init(struct in_addr /*addr*/, unsigned /*port*/);
1120
1121 /* --- @p_port@ --- *
1122  *
1123  * Arguments:   ---
1124  *
1125  * Returns:     Port number used for socket.
1126  */
1127
1128 unsigned p_port(void);
1129
1130 /* --- @p_create@ --- *
1131  *
1132  * Arguments:   @peerspec *spec@ = information about this peer
1133  *
1134  * Returns:     Pointer to the peer block, or null if it failed.
1135  *
1136  * Use:         Creates a new named peer block.  No peer is actually attached
1137  *              by this point.
1138  */
1139
1140 extern peer *p_create(peerspec */*spec*/);
1141
1142 /* --- @p_name@ --- *
1143  *
1144  * Arguments:   @peer *p@ = pointer to a peer block
1145  *
1146  * Returns:     A pointer to the peer's name.
1147  *
1148  * Use:         Equivalent to @p_spec(p)->name@.
1149  */
1150
1151 extern const char *p_name(peer */*p*/);
1152
1153 /* --- @p_spec@ --- *
1154  *
1155  * Arguments:   @peer *p@ = pointer to a peer block
1156  *
1157  * Returns:     Pointer to the peer's specification
1158  */
1159
1160 extern const peerspec *p_spec(peer */*p*/);
1161
1162 /* --- @p_findbyaddr@ --- *
1163  *
1164  * Arguments:   @const addr *a@ = address to look up
1165  *
1166  * Returns:     Pointer to the peer block, or null if not found.
1167  *
1168  * Use:         Finds a peer by address.
1169  */
1170
1171 extern peer *p_findbyaddr(const addr */*a*/);
1172
1173 /* --- @p_find@ --- *
1174  *
1175  * Arguments:   @const char *name@ = name to look up
1176  *
1177  * Returns:     Pointer to the peer block, or null if not found.
1178  *
1179  * Use:         Finds a peer by name.
1180  */
1181
1182 extern peer *p_find(const char */*name*/);
1183
1184 /* --- @p_destroy@ --- *
1185  *
1186  * Arguments:   @peer *p@ = pointer to a peer
1187  *
1188  * Returns:     ---
1189  *
1190  * Use:         Destroys a peer.
1191  */
1192
1193 extern void p_destroy(peer */*p*/);
1194
1195 /* --- @FOREACH_PEER@ --- *
1196  *
1197  * Arguments:   @p@ = name to bind to each peer
1198  *              @stuff@ = thing to do for each item
1199  *
1200  * Use:         Does something for each current peer.
1201  */
1202
1203 #define FOREACH_PEER(p, stuff) do {                                     \
1204   peer_iter i_;                                                         \
1205   peer *p;                                                              \
1206   for (p_mkiter(&i_); (p = p_next(&i_)) != 0; ) do stuff while (0);     \
1207 } while (0)
1208
1209 /* --- @p_mkiter@ --- *
1210  *
1211  * Arguments:   @peer_iter *i@ = pointer to an iterator
1212  *
1213  * Returns:     ---
1214  *
1215  * Use:         Initializes the iterator.
1216  */
1217
1218 extern void p_mkiter(peer_iter */*i*/);
1219
1220 /* --- @p_next@ --- *
1221  *
1222  * Arguments:   @peer_iter *i@ = pointer to an iterator
1223  *
1224  * Returns:     Next peer, or null if at the end.
1225  *
1226  * Use:         Returns the next peer.
1227  */
1228
1229 extern peer *p_next(peer_iter */*i*/);
1230
1231 /*----- Tunnel drivers ----------------------------------------------------*/
1232
1233 #ifdef TUN_LINUX
1234   extern const tunnel_ops tun_linux;
1235 #endif
1236
1237 #ifdef TUN_UNET
1238   extern const tunnel_ops tun_unet;
1239 #endif
1240
1241 #ifdef TUN_BSD
1242   extern const tunnel_ops tun_bsd;
1243 #endif
1244
1245 extern const tunnel_ops tun_slip;
1246
1247 /*----- Other handy utilities ---------------------------------------------*/
1248
1249 /* --- @mpstr@ --- *
1250  *
1251  * Arguments:   @mp *m@ = a multiprecision integer
1252  *
1253  * Returns:     A pointer to the integer's textual representation.
1254  *
1255  * Use:         Converts a multiprecision integer to a string.  Corrupts
1256  *              @buf_u@.
1257  */
1258
1259 extern const char *mpstr(mp */*m*/);
1260
1261 /* --- @gestr@ --- *
1262  *
1263  * Arguments:   @group *g@ = a group
1264  *              @ge *x@ = a group element
1265  *
1266  * Returns:     A pointer to the element's textual representation.
1267  *
1268  * Use:         Converts a group element to a string.  Corrupts
1269  *              @buf_u@.
1270  */
1271
1272 extern const char *gestr(group */*g*/, ge */*x*/);
1273
1274 /* --- @timestr@ --- *
1275  *
1276  * Arguments:   @time_t t@ = a time to convert
1277  *
1278  * Returns:     A pointer to a textual representation of the time.
1279  *
1280  * Use:         Converts a time to a textual representation.  Corrupts
1281  *              @buf_u@.
1282  */
1283
1284 extern const char *timestr(time_t /*t*/);
1285
1286 /* --- @mystrieq@ --- *
1287  *
1288  * Arguments:   @const char *x, *y@ = two strings
1289  *
1290  * Returns:     True if @x@ and @y are equal, up to case.
1291  */
1292
1293 extern int mystrieq(const char */*x*/, const char */*y*/);
1294
1295 /* --- @seq_reset@ --- *
1296  *
1297  * Arguments:   @seqwin *s@ = sequence-checking window
1298  *
1299  * Returns:     ---
1300  *
1301  * Use:         Resets a sequence number window.
1302  */
1303
1304 extern void seq_reset(seqwin */*s*/);
1305
1306 /* --- @seq_check@ --- *
1307  *
1308  * Arguments:   @seqwin *s@ = sequence-checking window
1309  *              @uint32 q@ = sequence number to check
1310  *              @const char *service@ = service to report message from
1311  *
1312  * Returns:     A @SEQ_@ code.
1313  *
1314  * Use:         Checks a sequence number against the window, updating things
1315  *              as necessary.
1316  */
1317
1318 extern int seq_check(seqwin */*s*/, uint32 /*q*/, const char */*service*/);
1319
1320 /*----- That's all, folks -------------------------------------------------*/
1321
1322 #ifdef __cplusplus
1323   }
1324 #endif
1325
1326 #endif