merge.c

   1 /*
   2  * merge.c - Routines to merge OpenPGP public keys.
   3  *
   4  * Jonathan McDowell <noodles@earth.li>
   5  *
   6  * Copyright 2002 Project Purple
   7  */
   8
   9 #include <assert.h>
  10 #include <stdio.h>
  11 #include <stdlib.h>
  12
  13 #include "decodekey.h"
  14 #include "keydb.h"
  15 #include "keyid.h"
  16 #include "keystructs.h"
  17 #include "ll.h"
  18 #include "log.h"
  19 #include "mem.h"
  20 #include "merge.h"
  21
  22 /**
  23  *      compare_packets - Check to see if 2 OpenPGP packets are the same.
  24  *      @a: The first packet to compare.
  25  *      @b: The second packet to compare.
  26  *
  27  *      Takes 2 packets and returns true if they are the same and false
  28  *      otherwise.
  29  */
  30 bool compare_packets(struct openpgp_packet *a, struct openpgp_packet *b)
  31 {
  32         return (a->tag == b->tag && a->length == b->length &&
  33                 !memcmp(a->data, b->data, b->length));
  34 }
  35
  36 /**
  37  *      compare_signatures - Check to see if 2 OpenPGP signatures are the same.
  38  *      @a: The first signature to compare.
  39  *      @b: The second signature to compare.
  40  *
  41  *      Takes 2 signature packets and returns true if they are the same and
  42  *      false otherwise.
  43  */
  44 bool compare_signatures(struct openpgp_packet *a, struct openpgp_packet *b)
  45 {
  46         return (sig_keyid(a) == sig_keyid(b));
  47 }
  48
  49 /**
  50  *      find_packet - Checks to see if an OpenPGP packet exists in a list.
  51  *      @packet_list: The list of packets to look in.
  52  *      @packet: The packet to look for.
  53  *
  54  *      Walks through the packet_list checking to see if the packet given is
  55  *      present in it. Returns true if it is.
  56  */
  57 bool find_packet(struct openpgp_packet_list *packet_list,
  58                         struct openpgp_packet *packet)
  59 {
  60         bool found = false;
  61
  62         while (!found && packet_list != NULL) {
  63                 if (compare_packets(packet_list->packet, packet)) {
  64                         found = true;
  65                 }
  66                 packet_list = packet_list -> next;
  67         }
  68
  69         return found;
  70 }
  71
  72 /**
  73  *      find_signature - Checks to see if an OpenPGP signature exists in a list.
  74  *      @packet_list: The list of packets to look in.
  75  *      @packet: The signature to look for.
  76  *
  77  *      Walks through the packet_list checking to see if the signature given is
  78  *      present in it. Returns a pointer to it if it is, NULL otherwise.
  79  *
  80  */
  81 struct openpgp_packet_list *find_signature(
  82                         struct openpgp_packet_list *packet_list,
  83                         struct openpgp_packet *packet)
  84 {
  85         struct openpgp_packet_list *found = NULL;
  86
  87         while (!found && packet_list != NULL) {
  88                 if (compare_signatures(packet_list->packet, packet)) {
  89                         found = packet_list;
  90                 }
  91                 packet_list = packet_list -> next;
  92         }
  93
  94         return found;
  95 }
  96
  97 /**
  98  *      get_signed_packet - Gets a signed packet from a list.
  99  *      @packet_list: The list of packets to look in.
 100  *      @packet: The packet to look for.
 101  *
 102  *      Walks through the signedpacket_list looking for the supplied packet and
 103  *      returns it if found. Otherwise returns NULL.
 104  */
 105 struct openpgp_signedpacket_list *find_signed_packet(
 106                 struct openpgp_signedpacket_list *packet_list,
 107                 struct openpgp_packet *packet)
 108 {
 109         struct openpgp_signedpacket_list *found = NULL;
 110
 111         while (found == NULL && packet_list != NULL) {
 112                 if (compare_packets(packet_list->packet, packet)) {
 113                         found = packet_list;
 114                 }
 115                 packet_list = packet_list -> next;
 116         }
 117
 118         return found;
 119 }
 120
 121 /**
 122  *      remove_signed_packet - Removes a signed packet from a list.
 123  *      @packet_list: The list of packets to look in.
 124  *      @packet: The packet to remove.
 125  *
 126  *      Walks through the signedpacket_list looking for the supplied packet and
 127  *      removes it if found. Assumes the packet can only exist a maximum of
 128  *      once in the list.
 129  */
 130 bool remove_signed_packet(struct openpgp_signedpacket_list **packet_list,
 131                 struct openpgp_signedpacket_list **list_end,
 132                 struct openpgp_packet *packet)
 133 {
 134         struct openpgp_signedpacket_list *cur = NULL;
 135         struct openpgp_signedpacket_list *prev = NULL;
 136         bool found = false;
 137
 138         for (cur = *packet_list; !found && (cur != NULL); cur = cur->next) {
 139                 if (compare_packets(cur->packet, packet)) {
 140                         found = true;
 141                         if (prev == NULL) {
 142                                 *packet_list = cur->next;
 143                         } else {
 144                                 prev->next = cur->next;
 145                         }
 146                         if (cur->next == NULL) {
 147                                 *list_end = prev;
 148                         }
 149                         // TODO: Free the removed signed packet...
 150                 }
 151                 prev = cur;
 152         }
 153
 154         return found;
 155 }
 156
 157 /**
 158  *      merge_packet_sigs - Takes 2 signed packets and merges their sigs.
 159  *      @old: The old signed packet.
 160  *      @new: The new signed packet.
 161  *
 162  *      Takes 2 signed packet list structures and the sigs of the packets on
 163  *      the head of these structures. These packets must both be the same and
 164  *      the fully merged structure is returned in old and the minimal
 165  *      difference to get from old to new in new.
 166  */
 167 int merge_packet_sigs(struct openpgp_signedpacket_list *old,
 168                         struct openpgp_signedpacket_list *new)
 169 {
 170         struct openpgp_packet_list      *lastpacket = NULL;
 171         struct openpgp_packet_list      *curpacket = NULL;
 172         struct openpgp_packet_list      *nextpacket = NULL;
 173
 174         assert(compare_packets(old->packet, new->packet));
 175
 176         curpacket = new->sigs;
 177         while (curpacket != NULL) {
 178                 nextpacket = curpacket->next;
 179                 /*
 180                  * TODO: We should be checking the signature and then
 181                  * potentially merging/replacing it depending on the subpackets
 182                  * really. For now this stops us adding the same one twice
 183                  * however.
 184                  */
 185                 if (find_signature(old->sigs, curpacket->packet)) {
 186                         /*
 187                          * We already have this sig, remove it from the
 188                          * difference list and free the memory allocated for
 189                          * it.
 190                          */
 191                         if (lastpacket != NULL) {
 192                                 lastpacket->next = curpacket->next;
 193                         } else {
 194                                 assert(curpacket == new->sigs);
 195                                 new->sigs = curpacket->next;
 196                         }
 197                         curpacket->next = NULL;
 198                         free_packet_list(curpacket);
 199                 } else {
 200                         lastpacket = curpacket;
 201                 }
 202                 curpacket = nextpacket;
 203         }
 204         new->last_sig = lastpacket;
 205
 206         /*
 207          * What's left on new->sigs now are the new signatures, so add them to
 208          * old->sigs.
 209          */
 210         packet_list_add(&old->sigs, &old->last_sig, new->sigs);
 211
 212         return 0;
 213 }
 214
 215 /**
 216  *      merge_signed_packets - Takes 2 lists of signed packets and merges them.
 217  *      @old: The old signed packet list.
 218  *      @new: The new signed packet list.
 219  *
 220  *      Takes 2 lists of signed packets and merges them. The complete list of
 221  *      signed packets & sigs is returned in old and the minimal set of
 222  *      differences required to get from old to new in new.
 223  */
 224 int merge_signed_packets(struct openpgp_signedpacket_list **old,
 225                         struct openpgp_signedpacket_list **old_end,
 226                         struct openpgp_signedpacket_list **new,
 227                         struct openpgp_signedpacket_list **new_end)
 228 {
 229         struct openpgp_signedpacket_list *curelem = NULL;
 230         struct openpgp_signedpacket_list *newelem = NULL;
 231
 232         for (curelem = *old; curelem != NULL; curelem = curelem->next) {
 233                 newelem = find_signed_packet(*new, curelem->packet);
 234                 if (newelem != NULL) {
 235                         merge_packet_sigs(curelem, newelem);
 236
 237                         /*
 238                          * If there are no sigs left on the new signed packet
 239                          * then remove it from the list.
 240                          */
 241                         if (newelem->sigs == NULL) {
 242                                 remove_signed_packet(new,
 243                                                 new_end,
 244                                                 newelem->packet);
 245                         }
 246                 }
 247         }
 248
 249         /*
 250          * If *new != NULL now then there might be UIDs on the new key that
 251          * weren't on the old key. Walk through them, checking if the UID is
 252          * on the old key and if not adding them to it.
 253          */
 254         for (curelem = *new; curelem != NULL;
 255                         curelem = curelem->next) {
 256
 257                 if (find_signed_packet(*old, curelem->packet) == NULL) {
 258                         ADD_PACKET_TO_LIST((*old_end),
 259                                 packet_dup(curelem->packet));
 260                         if (*old == NULL) {
 261                                 *old = *old_end;
 262                         }
 263                         packet_list_add(&(*old_end)->sigs,
 264                                 &(*old_end)->last_sig,
 265                                 curelem->sigs);
 266                 }
 267         }
 268
 269         return 0;
 270 }
 271
 272 /**
 273  *      merge_keys - Takes 2 public keys and merges them.
 274  *      @a: The old key. The merged key is returned in this structure.
 275  *      @b: The new key. The changed from old to new keys are returned in this
 276  *              structure.
 277  *
 278  *      This function takes 2 keys and merges them. It then returns the merged
 279  *      key in a and the difference between this new key and the original a
 280  *      in b (ie newb contains the minimum amount of detail necessary to
 281  *      convert olda to newa). The intention is that olda is provided from
 282  *      internal storage and oldb from the remote user. newa is then stored in
 283  *      internal storage and newb is sent to all our keysync peers.
 284  */
 285 int merge_keys(struct openpgp_publickey *a, struct openpgp_publickey *b)
 286 {
 287         int rc = 0; /* Return code */
 288         struct openpgp_packet_list      *curpacket = NULL;
 289         struct openpgp_packet_list      *lastpacket = NULL;
 290         struct openpgp_packet_list      *nextpacket = NULL;
 291
 292         if (a == NULL || b == NULL) {
 293                 /*
 294                  * Do nothing.
 295                  */
 296                 rc = 1;
 297         } else if (get_keyid(a) != get_keyid(b)) {
 298                 /*
 299                  * Key IDs are different.
 300                  */
 301                 rc = -1;
 302         } else {
 303                 /*
 304                  * Key IDs are the same, so I guess we have to merge them.
 305                  */
 306                 curpacket = b->revocations;
 307                 while (curpacket != NULL) {
 308                         nextpacket = curpacket->next;
 309                         if (find_packet(a->revocations, curpacket->packet)) {
 310                                 /*
 311                                  * We already have this revocation, remove it
 312                                  * from the difference list and free the memory
 313                                  * allocated for it.
 314                                  */
 315
 316                                 if (lastpacket != NULL) {
 317                                         lastpacket->next = curpacket->next;
 318                                 } else {
 319                                         assert(curpacket == b->revocations);
 320                                         b->revocations = curpacket->next;
 321                                 }
 322                                 curpacket->next = NULL;
 323                                 free_packet_list(curpacket);
 324
 325                         } else {
 326                                 lastpacket = curpacket;
 327                         }
 328                         curpacket = nextpacket;
 329                 }
 330                 b->last_revocation = lastpacket;
 331
 332                 /*
 333                  * Anything left on b->revocations doesn't exist on
 334                  * a->revocations, so add them to the list.
 335                  */
 336                 packet_list_add(&a->revocations,
 337                                 &a->last_revocation,
 338                                 b->revocations);
 339
 340                 /*
 341                  * Merge uids (signed list).
 342                  * Merge subkeys (signed list).
 343                  */
 344                 merge_signed_packets(&a->uids, &a->last_uid,
 345                                 &b->uids, &b->last_uid);
 346                 merge_signed_packets(&a->subkeys, &a->last_subkey,
 347                                 &b->subkeys, &b->last_subkey);
 348
 349         }
 350
 351         return rc;
 352 }
 353
 354 /**
 355  *      update_keys - Takes a list of public keys and updates them in the DB.
 356  *      @keys: The keys to update in the DB.
 357  *
 358  *      Takes a list of keys and adds them to the database, merging them with
 359  *      the key in the database if it's already present there. The key list is
 360  *      update to contain the minimum set of updates required to get from what
 361  *      we had before to what we have now (ie the set of data that was added to
 362  *      the DB). Returns the number of entirely new keys added.
 363  */
 364 int update_keys(struct openpgp_publickey **keys)
 365 {
 366         struct openpgp_publickey *curkey = NULL;
 367         struct openpgp_publickey *oldkey = NULL;
 368         struct openpgp_publickey *prev = NULL;
 369         int newkeys = 0;
 370         bool intrans;
 371
 372         for (curkey = *keys; curkey != NULL; curkey = curkey->next) {
 373                 intrans = starttrans();
 374                 logthing(LOGTHING_INFO,
 375                         "Fetching key 0x%llX, result: %d",
 376                         get_keyid(curkey),
 377                         fetch_key(get_keyid(curkey), &oldkey, intrans));
 378
 379                 /*
 380                  * If we already have the key stored in the DB then merge it
 381                  * with the new one that's been supplied. Otherwise the key
 382                  * we've just got is the one that goes in the DB and also the
 383                  * one that we send out.
 384                  */
 385                 if (oldkey != NULL) {
 386                         merge_keys(oldkey, curkey);
 387                         if (curkey->revocations == NULL &&
 388                                         curkey->uids == NULL &&
 389                                         curkey->subkeys == NULL) {
 390                                 if (prev == NULL) {
 391                                         *keys = curkey->next;
 392                                 } else {
 393                                         prev->next = curkey->next;
 394                                         curkey->next = NULL;
 395                                         free_publickey(curkey);
 396                                         curkey = prev;
 397                                 }
 398                         } else {
 399                                 prev = curkey;
 400                                 logthing(LOGTHING_INFO,
 401                                         "Merged key; storing updated key.");
 402                                 store_key(oldkey, intrans, true);
 403                         }
 404                         free_publickey(oldkey);
 405                         oldkey = NULL;
 406                 } else {
 407                         logthing(LOGTHING_INFO,
 408                                 "Storing completely new key.");
 409                         store_key(curkey, intrans, false);
 410                         newkeys++;
 411                 }
 412                 endtrans();
 413                 intrans = false;
 414         }
 415
 416         return newkeys;
 417 }