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