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 #include <string.h>
  13
  14 #include "decodekey.h"
  15 #include "keydb.h"
  16 #include "keyid.h"
  17 #include "keystructs.h"
  18 #include "ll.h"
  19 #include "log.h"
  20 #include "mem.h"
  21 #include "merge.h"
  22
  23 /**
  24  *      compare_packets - Check to see if 2 OpenPGP packets are the same.
  25  *      @a: The first packet to compare.
  26  *      @b: The second packet to compare.
  27  *
  28  *      Takes 2 packets and returns true if they are the same and false
  29  *      otherwise.
  30  */
  31 bool compare_packets(struct openpgp_packet *a, struct openpgp_packet *b)
  32 {
  33         return (a->tag == b->tag && a->length == b->length &&
  34                 !memcmp(a->data, b->data, b->length));
  35 }
  36
  37 /**
  38  *      compare_signatures - Check to see if 2 OpenPGP signatures are the same.
  39  *      @a: The first signature to compare.
  40  *      @b: The second signature to compare.
  41  *
  42  *      Takes 2 signature packets and returns true if they are the same and
  43  *      false otherwise.
  44  */
  45 bool compare_signatures(struct openpgp_packet *a, struct openpgp_packet *b)
  46 {
  47         return (sig_keyid(a) == sig_keyid(b));
  48 }
  49
  50 /**
  51  *      find_packet - Checks to see if an OpenPGP packet exists in a list.
  52  *      @packet_list: The list of packets to look in.
  53  *      @packet: The packet to look for.
  54  *
  55  *      Walks through the packet_list checking to see if the packet given is
  56  *      present in it. Returns true if it is.
  57  */
  58 bool find_packet(struct openpgp_packet_list *packet_list,
  59                         struct openpgp_packet *packet)
  60 {
  61         bool found = false;
  62
  63         while (!found && packet_list != NULL) {
  64                 if (compare_packets(packet_list->packet, packet)) {
  65                         found = true;
  66                 }
  67                 packet_list = packet_list -> next;
  68         }
  69
  70         return found;
  71 }
  72
  73 /**
  74  *      find_signature - Checks to see if an OpenPGP signature exists in a list.
  75  *      @packet_list: The list of packets to look in.
  76  *      @packet: The signature to look for.
  77  *
  78  *      Walks through the packet_list checking to see if the signature given is
  79  *      present in it. Returns a pointer to it if it is, NULL otherwise.
  80  *
  81  */
  82 struct openpgp_packet_list *find_signature(
  83                         struct openpgp_packet_list *packet_list,
  84                         struct openpgp_packet *packet)
  85 {
  86         struct openpgp_packet_list *found = NULL;
  87
  88         while (!found && packet_list != NULL) {
  89                 if (compare_signatures(packet_list->packet, packet)) {
  90                         found = packet_list;
  91                 }
  92                 packet_list = packet_list -> next;
  93         }
  94
  95         return found;
  96 }
  97
  98 /**
  99  *      get_signed_packet - Gets a signed packet from a list.
 100  *      @packet_list: The list of packets to look in.
 101  *      @packet: The packet to look for.
 102  *
 103  *      Walks through the signedpacket_list looking for the supplied packet and
 104  *      returns it if found. Otherwise returns NULL.
 105  */
 106 struct openpgp_signedpacket_list *find_signed_packet(
 107                 struct openpgp_signedpacket_list *packet_list,
 108                 struct openpgp_packet *packet)
 109 {
 110         struct openpgp_signedpacket_list *found = NULL;
 111
 112         while (found == NULL && packet_list != NULL) {
 113                 if (compare_packets(packet_list->packet, packet)) {
 114                         found = packet_list;
 115                 }
 116                 packet_list = packet_list -> next;
 117         }
 118
 119         return found;
 120 }
 121
 122 /**
 123  *      remove_signed_packet - Removes a signed packet from a list.
 124  *      @packet_list: The list of packets to look in.
 125  *      @packet: The packet to remove.
 126  *
 127  *      Walks through the signedpacket_list looking for the supplied packet and
 128  *      removes it if found. Assumes the packet can only exist a maximum of
 129  *      once in the list.
 130  */
 131 bool remove_signed_packet(struct openpgp_signedpacket_list **packet_list,
 132                 struct openpgp_signedpacket_list **list_end,
 133                 struct openpgp_packet *packet)
 134 {
 135         struct openpgp_signedpacket_list *cur = NULL;
 136         struct openpgp_signedpacket_list *prev = NULL;
 137         bool found = false;
 138
 139         for (cur = *packet_list; !found && (cur != NULL); cur = cur->next) {
 140                 if (compare_packets(cur->packet, packet)) {
 141                         found = true;
 142                         if (prev == NULL) {
 143                                 *packet_list = cur->next;
 144                         } else {
 145                                 prev->next = cur->next;
 146                         }
 147                         if (cur->next == NULL) {
 148                                 *list_end = prev;
 149                         }
 150                         // TODO: Free the removed signed packet...
 151                 }
 152                 prev = cur;
 153         }
 154
 155         return found;
 156 }
 157
 158 /**
 159  *      merge_packet_sigs - Takes 2 signed packets and merges their sigs.
 160  *      @old: The old signed packet.
 161  *      @new: The new signed packet.
 162  *
 163  *      Takes 2 signed packet list structures and the sigs of the packets on
 164  *      the head of these structures. These packets must both be the same and
 165  *      the fully merged structure is returned in old and the minimal
 166  *      difference to get from old to new in new.
 167  */
 168 int merge_packet_sigs(struct openpgp_signedpacket_list *old,
 169                         struct openpgp_signedpacket_list *new)
 170 {
 171         struct openpgp_packet_list      *lastpacket = NULL;
 172         struct openpgp_packet_list      *curpacket = NULL;
 173         struct openpgp_packet_list      *nextpacket = NULL;
 174
 175         assert(compare_packets(old->packet, new->packet));
 176
 177         curpacket = new->sigs;
 178         while (curpacket != NULL) {
 179                 nextpacket = curpacket->next;
 180                 /*
 181                  * TODO: We should be checking the signature and then
 182                  * potentially merging/replacing it depending on the subpackets
 183                  * really. For now this stops us adding the same one twice
 184                  * however.
 185                  */
 186                 if (find_signature(old->sigs, curpacket->packet)) {
 187                         /*
 188                          * We already have this sig, remove it from the
 189                          * difference list and free the memory allocated for
 190                          * it.
 191                          */
 192                         if (lastpacket != NULL) {
 193                                 lastpacket->next = curpacket->next;
 194                         } else {
 195                                 assert(curpacket == new->sigs);
 196                                 new->sigs = curpacket->next;
 197                         }
 198                         curpacket->next = NULL;
 199                         free_packet_list(curpacket);
 200                 } else {
 201                         lastpacket = curpacket;
 202                 }
 203                 curpacket = nextpacket;
 204         }
 205         new->last_sig = lastpacket;
 206
 207         /*
 208          * What's left on new->sigs now are the new signatures, so add them to
 209          * old->sigs.
 210          */
 211         packet_list_add(&old->sigs, &old->last_sig, new->sigs);
 212
 213         return 0;
 214 }
 215
 216 /**
 217  *      merge_signed_packets - Takes 2 lists of signed packets and merges them.
 218  *      @old: The old signed packet list.
 219  *      @new: The new signed packet list.
 220  *
 221  *      Takes 2 lists of signed packets and merges them. The complete list of
 222  *      signed packets & sigs is returned in old and the minimal set of
 223  *      differences required to get from old to new in new.
 224  */
 225 int merge_signed_packets(struct openpgp_signedpacket_list **old,
 226                         struct openpgp_signedpacket_list **old_end,
 227                         struct openpgp_signedpacket_list **new,
 228                         struct openpgp_signedpacket_list **new_end)
 229 {
 230         struct openpgp_signedpacket_list *curelem = NULL;
 231         struct openpgp_signedpacket_list *newelem = NULL;
 232
 233         for (curelem = *old; curelem != NULL; curelem = curelem->next) {
 234                 newelem = find_signed_packet(*new, curelem->packet);
 235                 if (newelem != NULL) {
 236                         merge_packet_sigs(curelem, newelem);
 237
 238                         /*
 239                          * If there are no sigs left on the new signed packet
 240                          * then remove it from the list.
 241                          */
 242                         if (newelem->sigs == NULL) {
 243                                 remove_signed_packet(new,
 244                                                 new_end,
 245                                                 newelem->packet);
 246                         }
 247                 }
 248         }
 249
 250         /*
 251          * If *new != NULL now then there might be UIDs on the new key that
 252          * weren't on the old key. Walk through them, checking if the UID is
 253          * on the old key and if not adding them to it.
 254          */
 255         for (curelem = *new; curelem != NULL;
 256                         curelem = curelem->next) {
 257
 258                 if (find_signed_packet(*old, curelem->packet) == NULL) {
 259                         ADD_PACKET_TO_LIST((*old_end),
 260                                 packet_dup(curelem->packet));
 261                         if (*old == NULL) {
 262                                 *old = *old_end;
 263                         }
 264                         packet_list_add(&(*old_end)->sigs,
 265                                 &(*old_end)->last_sig,
 266                                 curelem->sigs);
 267                 }
 268         }
 269
 270         return 0;
 271 }
 272
 273 /**
 274  *      merge_keys - Takes 2 public keys and merges them.
 275  *      @a: The old key. The merged key is returned in this structure.
 276  *      @b: The new key. The changed from old to new keys are returned in this
 277  *              structure.
 278  *
 279  *      This function takes 2 keys and merges them. It then returns the merged
 280  *      key in a and the difference between this new key and the original a
 281  *      in b (ie newb contains the minimum amount of detail necessary to
 282  *      convert olda to newa). The intention is that olda is provided from
 283  *      internal storage and oldb from the remote user. newa is then stored in
 284  *      internal storage and newb is sent to all our keysync peers.
 285  */
 286 int merge_keys(struct openpgp_publickey *a, struct openpgp_publickey *b)
 287 {
 288         int rc = 0; /* Return code */
 289         struct openpgp_packet_list      *curpacket = NULL;
 290         struct openpgp_packet_list      *lastpacket = NULL;
 291         struct openpgp_packet_list      *nextpacket = NULL;
 292
 293         if (a == NULL || b == NULL) {
 294                 /*
 295                  * Do nothing.
 296                  */
 297                 rc = 1;
 298         } else if (get_keyid(a) != get_keyid(b)) {
 299                 /*
 300                  * Key IDs are different.
 301                  */
 302                 rc = -1;
 303         } else {
 304                 /*
 305                  * Key IDs are the same, so I guess we have to merge them.
 306                  */
 307                 curpacket = b->revocations;
 308                 while (curpacket != NULL) {
 309                         nextpacket = curpacket->next;
 310                         if (find_packet(a->revocations, curpacket->packet)) {
 311                                 /*
 312                                  * We already have this revocation, remove it
 313                                  * from the difference list and free the memory
 314                                  * allocated for it.
 315                                  */
 316
 317                                 if (lastpacket != NULL) {
 318                                         lastpacket->next = curpacket->next;
 319                                 } else {
 320                                         assert(curpacket == b->revocations);
 321                                         b->revocations = curpacket->next;
 322                                 }
 323                                 curpacket->next = NULL;
 324                                 free_packet_list(curpacket);
 325
 326                         } else {
 327                                 lastpacket = curpacket;
 328                         }
 329                         curpacket = nextpacket;
 330                 }
 331                 b->last_revocation = lastpacket;
 332
 333                 /*
 334                  * Anything left on b->revocations doesn't exist on
 335                  * a->revocations, so add them to the list.
 336                  */
 337                 packet_list_add(&a->revocations,
 338                                 &a->last_revocation,
 339                                 b->revocations);
 340
 341                 /*
 342                  * Merge uids (signed list).
 343                  * Merge subkeys (signed list).
 344                  */
 345                 merge_signed_packets(&a->uids, &a->last_uid,
 346                                 &b->uids, &b->last_uid);
 347                 merge_signed_packets(&a->subkeys, &a->last_subkey,
 348                                 &b->subkeys, &b->last_subkey);
 349
 350         }
 351
 352         return rc;
 353 }
 354
 355 /**
 356  *      update_keys - Takes a list of public keys and updates them in the DB.
 357  *      @keys: The keys to update in the DB.
 358  *
 359  *      Takes a list of keys and adds them to the database, merging them with
 360  *      the key in the database if it's already present there. The key list is
 361  *      update to contain the minimum set of updates required to get from what
 362  *      we had before to what we have now (ie the set of data that was added to
 363  *      the DB). Returns the number of entirely new keys added.
 364  */
 365 int update_keys(struct openpgp_publickey **keys)
 366 {
 367         struct openpgp_publickey *curkey = NULL;
 368         struct openpgp_publickey *oldkey = NULL;
 369         struct openpgp_publickey *prev = NULL;
 370         int newkeys = 0;
 371         bool intrans;
 372
 373         for (curkey = *keys; curkey != NULL; curkey = curkey->next) {
 374                 intrans = starttrans();
 375                 logthing(LOGTHING_INFO,
 376                         "Fetching key 0x%llX, result: %d",
 377                         get_keyid(curkey),
 378                         fetch_key(get_keyid(curkey), &oldkey, intrans));
 379
 380                 /*
 381                  * If we already have the key stored in the DB then merge it
 382                  * with the new one that's been supplied. Otherwise the key
 383                  * we've just got is the one that goes in the DB and also the
 384                  * one that we send out.
 385                  */
 386                 if (oldkey != NULL) {
 387                         merge_keys(oldkey, curkey);
 388                         if (curkey->revocations == NULL &&
 389                                         curkey->uids == NULL &&
 390                                         curkey->subkeys == NULL) {
 391                                 if (prev == NULL) {
 392                                         *keys = curkey->next;
 393                                 } else {
 394                                         prev->next = curkey->next;
 395                                         curkey->next = NULL;
 396                                         free_publickey(curkey);
 397                                         curkey = prev;
 398                                 }
 399                         } else {
 400                                 prev = curkey;
 401                                 logthing(LOGTHING_INFO,
 402                                         "Merged key; storing updated key.");
 403                                 store_key(oldkey, intrans, true);
 404                         }
 405                         free_publickey(oldkey);
 406                         oldkey = NULL;
 407                 } else {
 408                         logthing(LOGTHING_INFO,
 409                                 "Storing completely new key.");
 410                         store_key(curkey, intrans, false);
 411                         newkeys++;
 412                 }
 413                 endtrans();
 414                 intrans = false;
 415         }
 416
 417         return newkeys;
 418 }