ucert.c

   1 /*
   2  * Copyright (C) 2018 Daniel Golle <daniel@makrotopia.org>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 3
   6  * as published by the Free Software Foundation
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  */
  13
  14 #define _GNU_SOURCE
  15
  16 #include <fcntl.h>
  17 #include <dlfcn.h>
  18 #include <stdio.h>
  19 #include <stdbool.h>
  20 #include <stdlib.h>
  21 #include <string.h>
  22 #include <getopt.h>
  23 #include <stdint.h>
  24 #include <unistd.h>
  25 #include <inttypes.h>
  26 #include <sys/stat.h>
  27 #include <sys/wait.h>
  28
  29 #include <json-c/json.h>
  30 #include <libubox/blob.h>
  31 #include <libubox/utils.h>
  32 #include <libubox/list.h>
  33 #include <libubox/vlist.h>
  34 #include <libubox/blobmsg_json.h>
  35
  36 #include "usign.h"
  37
  38 #define CERT_BUF_LEN 4096
  39
  40 static enum {
  41         CMD_APPEND,
  42         CMD_DUMP,
  43         CMD_ISSUE,
  44         CMD_REVOKE,
  45         CMD_VERIFY,
  46         CMD_NONE,
  47 } cmd = CMD_NONE;
  48
  49 static bool quiet;
  50
  51 enum cert_attr {
  52         CERT_ATTR_SIGNATURE,
  53         CERT_ATTR_PAYLOAD,
  54         CERT_ATTR_MAX
  55 };
  56
  57 static const struct blob_attr_info cert_policy[CERT_ATTR_MAX] = {
  58         [CERT_ATTR_SIGNATURE] = { .type = BLOB_ATTR_BINARY },
  59         [CERT_ATTR_PAYLOAD] = { .type = BLOB_ATTR_NESTED },
  60 };
  61
  62 enum cert_cont_attr {
  63         CERT_CT_ATTR_PAYLOAD,
  64         CERT_CT_ATTR_MAX
  65 };
  66
  67 static const struct blobmsg_policy cert_cont_policy[CERT_CT_ATTR_MAX] = {
  68         [CERT_CT_ATTR_PAYLOAD] = { .name = "ucert", .type = BLOBMSG_TYPE_TABLE },
  69 };
  70
  71 enum cert_payload_attr {
  72         CERT_PL_ATTR_CERTTYPE,
  73         CERT_PL_ATTR_CERTID,
  74         CERT_PL_ATTR_VALIDFROMTIME,
  75         CERT_PL_ATTR_EXPIRETIME,
  76         CERT_PL_ATTR_PUBKEY,
  77         CERT_PL_ATTR_KEY_FINGERPRINT,
  78         CERT_PL_ATTR_MAX
  79 };
  80
  81 enum certtype_id {
  82         CERTTYPE_UNSPEC,
  83         CERTTYPE_AUTH,
  84         CERTTYPE_REVOKE
  85 };
  86
  87 static const struct blobmsg_policy cert_payload_policy[CERT_PL_ATTR_MAX] = {
  88         [CERT_PL_ATTR_CERTTYPE] = { .name = "certtype", .type = BLOBMSG_TYPE_INT32 },
  89         [CERT_PL_ATTR_CERTID] = { .name = "certid", .type = BLOBMSG_TYPE_INT32 },
  90         [CERT_PL_ATTR_VALIDFROMTIME] = { .name = "validfrom", .type = BLOBMSG_TYPE_INT64 },
  91         [CERT_PL_ATTR_EXPIRETIME] = { .name = "expiresat", .type = BLOBMSG_TYPE_INT64 },
  92         [CERT_PL_ATTR_PUBKEY] = { .name = "pubkey", .type = BLOBMSG_TYPE_STRING },
  93         [CERT_PL_ATTR_KEY_FINGERPRINT] = { .name = "fingerprint", .type = BLOBMSG_TYPE_STRING },
  94 };
  95
  96 struct cert_object {
  97         struct list_head list;
  98         struct blob_attr *cert[CERT_ATTR_MAX];
  99 };
 100
 101 static int write_file(const char *filename, void *buf, size_t len, bool append) {
 102         FILE *f;
 103         size_t outlen;
 104
 105         f = fopen(filename, append?"a":"w");
 106         if (!f)
 107                 return 1;
 108
 109         outlen = fwrite(buf, 1, len, f);
 110         fclose(f);
 111         return (outlen == len);
 112 }
 113
 114 static int cert_load(const char *certfile, struct list_head *chain) {
 115         FILE *f;
 116         struct blob_attr *certtb[CERT_ATTR_MAX];
 117         struct blob_attr *bufpt;
 118         struct cert_object *cobj;
 119         char filebuf[CERT_BUF_LEN];
 120         int ret = 0, pret = 0;
 121         int len, pos = 0;
 122
 123         f = fopen(certfile, "r");
 124         if (!f)
 125                 return 1;
 126
 127         len = fread(&filebuf, 1, CERT_BUF_LEN - 1, f);
 128         if (len < 64)
 129                 return 1;
 130
 131         ret = ferror(f) || !feof(f);
 132         fclose(f);
 133         if (ret)
 134                 return 1;
 135
 136         bufpt = (struct blob_attr *)filebuf;
 137         do {
 138                 pret = blob_parse(bufpt, certtb, cert_policy, CERT_ATTR_MAX);
 139                 if (pret <= 0)
 140                         /* no attributes found */
 141                         break;
 142
 143                 if (pos + blob_pad_len(bufpt) > len)
 144                         /* blob exceeds filebuffer */
 145                         break;
 146                 else
 147                         pos += blob_pad_len(bufpt);
 148
 149                 cobj = calloc(1, sizeof(*cobj));
 150                 memcpy(cobj->cert, &certtb, sizeof(certtb));
 151                 list_add_tail(&cobj->list, chain);
 152                 ret += pret;
 153                 bufpt = blob_next(bufpt);
 154         /* repeat parsing while there is still enough remaining data in buffer */
 155         } while(len > pos + sizeof(struct blob_attr));
 156
 157         return (ret <= 0);
 158 }
 159
 160 static int cert_append(const char *certfile, const char *sigfile) {
 161         FILE *fs;
 162         char filebuf[CERT_BUF_LEN];
 163         struct blob_buf sigbuf;
 164         int len;
 165         int ret;
 166
 167         fs = fopen(sigfile, "r");
 168         if (!fs)
 169                 return 1;
 170
 171         len = fread(&filebuf, 1, CERT_BUF_LEN - 1, fs);
 172         ret = ferror(fs) || !feof(fs) || (len < 64);
 173         fclose(fs);
 174         if (ret)
 175                 return 1;
 176
 177         blob_buf_init(&sigbuf, 0);
 178         blob_put(&sigbuf, CERT_ATTR_SIGNATURE, filebuf, len);
 179         ret = write_file(certfile, sigbuf.head, blob_raw_len(sigbuf.head), true);
 180         blob_buf_free(&sigbuf);
 181         return ret;
 182 }
 183
 184 static int cert_verify_blob(struct blob_attr *cert[CERT_ATTR_MAX],
 185                        const char *pubkeyfile, const char *pubkeydir) {
 186         int i;
 187         char msgfname[256], sigfname[256];
 188         int ret;
 189         char tmpdir[] = "/tmp/ucert-XXXXXX";
 190
 191         if (mkdtemp(tmpdir) == NULL)
 192                 return errno;
 193
 194         snprintf(msgfname, sizeof(msgfname) - 1, "%s/%s", tmpdir, "payload");
 195         snprintf(sigfname, sizeof(sigfname) - 1, "%s/%s", tmpdir, "payload.sig");
 196
 197         for (i = 0; i < CERT_ATTR_MAX; i++) {
 198                 struct blob_attr *v = cert[i];
 199
 200                 if (!v)
 201                         break;
 202
 203                 switch(cert_policy[i].type) {
 204                 case BLOB_ATTR_BINARY:
 205                         write_file(sigfname, blob_data(v), blob_len(v), false);
 206                         break;
 207                 case BLOB_ATTR_NESTED:
 208                         write_file(msgfname, blob_data(v), blob_len(v), false);
 209                         break;
 210                 }
 211         }
 212
 213         ret = usign_v(msgfname, pubkeyfile, pubkeydir, sigfname, quiet);
 214
 215         unlink(msgfname);
 216         unlink(sigfname);
 217         rmdir(tmpdir);
 218
 219         return ret;
 220 }
 221
 222 static int chain_verify(const char *msgfile, const char *pubkeyfile,
 223                         const char *pubkeydir, struct list_head *chain) {
 224         struct cert_object *cobj;
 225         struct blob_attr *containertb[CERT_CT_ATTR_MAX];
 226         struct blob_attr *payloadtb[CERT_PL_ATTR_MAX];
 227         char tmpdir[] = "/tmp/ucert-XXXXXX";
 228         char chainedpubkey[256] = {0};
 229         char chainedfp[17] = {0};
 230         char extsigfile[256] = {0};
 231         int ret = 1;
 232         int checkmsg = 0;
 233
 234         if (mkdtemp(tmpdir) == NULL)
 235                 return errno;
 236
 237         if (msgfile)
 238                 checkmsg = -1;
 239
 240         list_for_each_entry(cobj, chain, list) {
 241                 /* blob has payload, verify that using signature */
 242                 if (cobj->cert[CERT_ATTR_PAYLOAD]) {
 243                         struct timeval tv;
 244                         uint64_t validfrom;
 245                         uint64_t expiresat;
 246                         uint32_t certtype;
 247
 248                         ret = cert_verify_blob(cobj->cert, chainedpubkey[0]?chainedpubkey:pubkeyfile, pubkeydir);
 249                         if (ret)
 250                                 goto clean_and_return;
 251
 252                         blobmsg_parse(cert_cont_policy,
 253                                       ARRAY_SIZE(cert_cont_policy),
 254                                       containertb,
 255                                       blob_data(cobj->cert[CERT_ATTR_PAYLOAD]),
 256                                       blob_len(cobj->cert[CERT_ATTR_PAYLOAD]));
 257                         if (!containertb[CERT_CT_ATTR_PAYLOAD]) {
 258                                 ret = 1;
 259                                 fprintf(stderr, "no ucert in signed payload\n");
 260                                 goto clean_and_return;
 261                         }
 262                         blobmsg_parse(cert_payload_policy,
 263                                       ARRAY_SIZE(cert_payload_policy),
 264                                       payloadtb,
 265                                       blobmsg_data(containertb[CERT_CT_ATTR_PAYLOAD]),
 266                                       blobmsg_data_len(containertb[CERT_CT_ATTR_PAYLOAD]));
 267
 268                         if (!payloadtb[CERT_PL_ATTR_CERTTYPE] ||
 269                             !payloadtb[CERT_PL_ATTR_VALIDFROMTIME] ||
 270                             !payloadtb[CERT_PL_ATTR_EXPIRETIME] ||
 271                             !payloadtb[CERT_PL_ATTR_PUBKEY]) {
 272                                 ret = 1;
 273                                 fprintf(stderr, "missing mandatory ucert attributes\n");
 274                                 goto clean_and_return;
 275                         }
 276                         certtype = blobmsg_get_u32(payloadtb[CERT_PL_ATTR_CERTTYPE]);
 277                         validfrom = blobmsg_get_u64(payloadtb[CERT_PL_ATTR_VALIDFROMTIME]);
 278                         expiresat = blobmsg_get_u64(payloadtb[CERT_PL_ATTR_EXPIRETIME]);
 279
 280                         if (certtype != CERTTYPE_AUTH) {
 281                                 ret = 2;
 282                                 fprintf(stderr, "wrong certificate type\n");
 283                                 goto clean_and_return;
 284                         }
 285
 286                         gettimeofday(&tv, NULL);
 287                         if (tv.tv_sec < validfrom ||
 288                             tv.tv_sec >= expiresat) {
 289                                 ret = 3;
 290                                 fprintf(stderr, "certificate expired\n");
 291                                 goto clean_and_return;
 292                         }
 293
 294                         snprintf(chainedpubkey, sizeof(chainedpubkey) - 1, "%s/%s", tmpdir, "chained-pubkey");
 295                         write_file(chainedpubkey,
 296                                    blobmsg_data(payloadtb[CERT_PL_ATTR_PUBKEY]),
 297                                    blobmsg_data_len(payloadtb[CERT_PL_ATTR_PUBKEY]),
 298                                    false);
 299
 300                         if (usign_f_pubkey(chainedfp, chainedpubkey)) {
 301                                 if (!quiet)
 302                                         fprintf(stderr, "cannot get fingerprint for chained key\n");
 303                                 ret = 2;
 304                                 goto clean_and_return;
 305                         }
 306                         if (pubkeydir && _usign_key_is_revoked(chainedfp, pubkeydir)) {
 307                                 if (!quiet)
 308                                         fprintf(stderr, "key %s has been revoked!\n", chainedfp);
 309                                 ret = 4;
 310                                 goto clean_and_return;
 311                         }
 312                 } else {
 313                 /* blob doesn't have payload, verify message using signature */
 314                         if (msgfile) {
 315                                 snprintf(extsigfile, sizeof(extsigfile) - 1, "%s/%s", tmpdir, "ext-sig");
 316                                 write_file(extsigfile,
 317                                            blob_data(cobj->cert[CERT_ATTR_SIGNATURE]),
 318                                            blob_len(cobj->cert[CERT_ATTR_SIGNATURE]),
 319                                            false);
 320                                 checkmsg = ret = usign_v(msgfile,
 321                                               chainedpubkey[0]?chainedpubkey:pubkeyfile,
 322                                               pubkeydir, extsigfile, quiet);
 323                                 unlink(extsigfile);
 324                         } else {
 325                                 fprintf(stderr, "stray trailing signature without anything to verify!\n");
 326                                 ret = 1;
 327                         };
 328                 }
 329         }
 330
 331         if (checkmsg == -1)
 332                 fprintf(stderr, "missing signature to verify message!\n");
 333
 334 clean_and_return:
 335         if (chainedpubkey[0])
 336                 unlink(chainedpubkey);
 337         rmdir(tmpdir);
 338         return ret | checkmsg;
 339 }
 340
 341 static void cert_dump_blob(struct blob_attr *cert[CERT_ATTR_MAX]) {
 342         int i;
 343
 344         for (i = 0; i < CERT_ATTR_MAX; i++) {
 345                 struct blob_attr *v = cert[i];
 346
 347                 if (!v)
 348                         continue;
 349
 350                 switch(cert_policy[i].type) {
 351                 case BLOB_ATTR_BINARY:
 352                         fprintf(stdout, "signature:\n---\n%s---\n", (char *) blob_data(v));
 353                         break;
 354                 case BLOB_ATTR_NESTED:
 355                         fprintf(stdout, "payload:\n---\n%s\n---\n", blobmsg_format_json_indent(blob_data(v), false, 0));
 356                         break;
 357                 }
 358         }
 359 }
 360
 361 static int cert_dump(const char *certfile) {
 362         struct cert_object *cobj;
 363         static LIST_HEAD(certchain);
 364         unsigned int count = 0;
 365
 366         if (cert_load(certfile, &certchain)) {
 367                 fprintf(stderr, "cannot parse cert\n");
 368                 return 1;
 369         }
 370
 371         list_for_each_entry(cobj, &certchain, list) {
 372                 fprintf(stderr, "=== CHAIN ELEMENT %02u ===\n", ++count);
 373                 cert_dump_blob(cobj->cert);
 374                 fprintf(stderr, "========================\n");
 375         }
 376
 377         return 0;
 378 }
 379
 380 static int cert_issue(const char *certfile, const char *pubkeyfile, const char *seckeyfile) {
 381         struct blob_buf certbuf;
 382         struct blob_buf payloadbuf;
 383         struct timeval tv;
 384         struct stat st;
 385         int pklen, siglen;
 386         int revoker = 1;
 387         void *c;
 388         FILE *pkf, *sigf;
 389         char pkb[512];
 390         char sigb[512];
 391         char fname[256], sfname[256];
 392         char pkfp[17];
 393         char tmpdir[] = "/tmp/ucert-XXXXXX";
 394
 395         if (stat(certfile, &st) == 0) {
 396                 fprintf(stderr, "certfile %s exists, won't overwrite.\n", certfile);
 397                 return -1;
 398         }
 399
 400         pkf = fopen(pubkeyfile, "r");
 401         if (!pkf)
 402                 return -1;
 403
 404         pklen = fread(pkb, 1, 512, pkf);
 405         pkb[pklen] = '\0';
 406
 407         if (pklen < 32)
 408                 return -1;
 409
 410         fclose(pkf);
 411
 412         if (usign_f_pubkey(pkfp, pubkeyfile))
 413                 return -1;
 414
 415         gettimeofday(&tv, NULL);
 416
 417         if (mkdtemp(tmpdir) == NULL)
 418                 return errno;
 419
 420         while (revoker >= 0) {
 421                 blob_buf_init(&payloadbuf, 0);
 422                 c = blobmsg_open_table(&payloadbuf, "ucert");
 423                 blobmsg_add_u32(&payloadbuf, "certtype", revoker?CERTTYPE_REVOKE:CERTTYPE_AUTH);
 424                 blobmsg_add_u64(&payloadbuf, "validfrom", tv.tv_sec);
 425                 if (!revoker) {
 426                         blobmsg_add_u64(&payloadbuf, "expiresat", tv.tv_sec + 60 * 60 * 24 * 365);
 427                         blobmsg_add_string(&payloadbuf, "pubkey", pkb);
 428                 } else {
 429                         blobmsg_add_string(&payloadbuf, "fingerprint", pkfp);
 430                 }
 431
 432                 blobmsg_close_table(&payloadbuf, c);
 433
 434                 snprintf(fname, sizeof(fname) - 1, "%s/%s", tmpdir, revoker?"revoker":"payload");
 435                 write_file(fname, blob_data(payloadbuf.head), blob_len(payloadbuf.head), false);
 436
 437                 snprintf(sfname, sizeof(sfname) - 1, "%s/%s", tmpdir, revoker?"revoker.sig":"payload.sig");
 438                 if (usign_s(fname, seckeyfile, sfname, quiet))
 439                         return 1;
 440
 441                 sigf = fopen(sfname, "r");
 442                 if (!sigf)
 443                         return 1;
 444
 445                 siglen = fread(sigb, 1, 1024, sigf);
 446                 if (siglen < 1)
 447                         return 1;
 448
 449                 sigb[siglen] = '\0';
 450                 fclose(sigf);
 451
 452                 unlink(fname);
 453                 unlink(sfname);
 454
 455                 blob_buf_init(&certbuf, 0);
 456                 blob_put(&certbuf, CERT_ATTR_SIGNATURE, sigb, siglen);
 457                 blob_put(&certbuf, CERT_ATTR_PAYLOAD, blob_data(payloadbuf.head), blob_len(payloadbuf.head));
 458                 snprintf(fname, sizeof(fname) - 1, "%s%s", certfile, revoker?".revoke":"");
 459                 write_file(fname, certbuf.head, blob_raw_len(certbuf.head), false);
 460                 blob_buf_free(&certbuf);
 461                 blob_buf_free(&payloadbuf);
 462
 463                 revoker--;
 464         }
 465
 466         rmdir(tmpdir);
 467
 468         return 0;
 469 }
 470
 471 static int cert_process_revoker(const char *certfile, const char *pubkeydir) {
 472         static LIST_HEAD(certchain);
 473         struct cert_object *cobj;
 474         struct blob_attr *containertb[CERT_CT_ATTR_MAX];
 475         struct blob_attr *payloadtb[CERT_PL_ATTR_MAX];
 476         struct stat st;
 477         struct timeval tv;
 478         uint64_t validfrom;
 479         uint32_t certtype;
 480         char *fingerprint;
 481         char rfname[512];
 482
 483         int ret;
 484
 485         if (cert_load(certfile, &certchain)) {
 486                 fprintf(stderr, "cannot parse cert\n");
 487                 return 1;
 488         }
 489
 490         list_for_each_entry(cobj, &certchain, list) {
 491                 /* blob has payload, verify that using signature */
 492                 if (!cobj->cert[CERT_ATTR_PAYLOAD])
 493                         return 2;
 494                 ret = cert_verify_blob(cobj->cert, NULL, pubkeydir);
 495                 if (ret)
 496                         return ret;
 497
 498                 blobmsg_parse(cert_cont_policy,
 499                               ARRAY_SIZE(cert_cont_policy),
 500                               containertb,
 501                               blob_data(cobj->cert[CERT_ATTR_PAYLOAD]),
 502                               blob_len(cobj->cert[CERT_ATTR_PAYLOAD]));
 503                 if (!containertb[CERT_CT_ATTR_PAYLOAD]) {
 504                         fprintf(stderr, "no ucert in signed payload\n");
 505                         return 2;
 506                 }
 507
 508                 blobmsg_parse(cert_payload_policy,
 509                               ARRAY_SIZE(cert_payload_policy),
 510                               payloadtb,
 511                               blobmsg_data(containertb[CERT_CT_ATTR_PAYLOAD]),
 512                               blobmsg_data_len(containertb[CERT_CT_ATTR_PAYLOAD]));
 513
 514                 if (!payloadtb[CERT_PL_ATTR_CERTTYPE] ||
 515                     !payloadtb[CERT_PL_ATTR_VALIDFROMTIME] ||
 516                     !payloadtb[CERT_PL_ATTR_KEY_FINGERPRINT]) {
 517                         fprintf(stderr, "missing mandatory ucert attributes\n");
 518                         return 2;
 519                 }
 520
 521                 certtype = blobmsg_get_u32(payloadtb[CERT_PL_ATTR_CERTTYPE]);
 522                 validfrom = blobmsg_get_u64(payloadtb[CERT_PL_ATTR_VALIDFROMTIME]);
 523                 fingerprint = blobmsg_get_string(payloadtb[CERT_PL_ATTR_KEY_FINGERPRINT]);
 524
 525                 if (certtype != CERTTYPE_REVOKE) {
 526                         fprintf(stderr, "wrong certificate type\n");
 527                         return 2;
 528                 }
 529
 530                 gettimeofday(&tv, NULL);
 531                 if (tv.tv_sec < validfrom) {
 532                         return 3;
 533                 }
 534
 535                 snprintf(rfname, sizeof(rfname)-1, "%s/%s", pubkeydir, fingerprint);
 536                 /* check if entry in pubkeydir exists */
 537                 if (stat(rfname, &st) == 0) {
 538                         if (_usign_key_is_revoked(fingerprint, pubkeydir)) {
 539                                 if (!quiet)
 540                                         fprintf(stdout, "existing revoker deadlink for key %s\n", fingerprint);
 541                                 continue;
 542                         };
 543
 544                         /* remove any other entry */
 545                         if (unlink(rfname))
 546                                 return -1;
 547                 }
 548
 549                 ret = symlink(".revoked.", rfname);
 550                 if (ret)
 551                         return ret;
 552
 553                 if (!quiet)
 554                         fprintf(stdout, "created revoker deadlink for key %s\n", fingerprint);
 555         };
 556
 557         return ret;
 558 }
 559
 560 static int cert_verify(const char *certfile, const char *pubkeyfile, const char *pubkeydir, const char *msgfile) {
 561         static LIST_HEAD(certchain);
 562
 563         if (cert_load(certfile, &certchain)) {
 564                 fprintf(stderr, "cannot parse cert\n");
 565                 return 1;
 566         }
 567
 568         return chain_verify(msgfile, pubkeyfile, pubkeydir, &certchain);
 569 }
 570
 571 static int usage(const char *cmd)
 572 {
 573         fprintf(stderr,
 574                 "Usage: %s <command> <options>\n"
 575                 "Commands:\n"
 576                 "  -A:                  append signature (needs -c and -x)\n"
 577                 "  -D:                  dump (needs -c)\n"
 578                 "  -I:                  issue cert and revoker (needs -c and -p and -s)\n"
 579                 "  -R:                  process revoker certificate (needs -c and -P)\n"
 580                 "  -V:                  verify (needs -c and -p|-P, may have -m)\n"
 581                 "Options:\n"
 582                 "  -c <file>:           certificate file\n"
 583                 "  -m <file>:           message file (verify only)\n"
 584                 "  -p <file>:           public key file\n"
 585                 "  -P <path>:           public key directory (verify only)\n"
 586                 "  -q:                  quiet (do not print verification result, use return code only)\n"
 587                 "  -s <file>:           secret key file (issue only)\n"
 588                 "  -x <file>:           signature file\n"
 589                 "\n",
 590                 cmd);
 591         return 1;
 592 }
 593
 594 int main(int argc, char *argv[]) {
 595         int ch;
 596         const char *msgfile = NULL;
 597         const char *sigfile = NULL;
 598         const char *pubkeyfile = NULL;
 599         const char *pubkeydir = NULL;
 600         const char *certfile = NULL;
 601         const char *seckeyfile = NULL;
 602
 603         quiet = false;
 604         while ((ch = getopt(argc, argv, "ADIRVc:m:p:P:qs:x:")) != -1) {
 605                 switch (ch) {
 606                 case 'A':
 607                         cmd = CMD_APPEND;
 608                         break;
 609                 case 'D':
 610                         cmd = CMD_DUMP;
 611                         break;
 612                 case 'I':
 613                         cmd = CMD_ISSUE;
 614                         break;
 615                 case 'R':
 616                         cmd = CMD_REVOKE;
 617                         break;
 618                 case 'V':
 619                         cmd = CMD_VERIFY;
 620                         break;
 621                 case 'c':
 622                         certfile = optarg;
 623                         break;
 624                 case 'm':
 625                         msgfile = optarg;
 626                         break;
 627                 case 'p':
 628                         pubkeyfile = optarg;
 629                         break;
 630                 case 'P':
 631                         pubkeydir = optarg;
 632                         break;
 633                 case 'q':
 634                         quiet = true;
 635                         break;
 636                 case 's':
 637                         seckeyfile = optarg;
 638                         break;
 639                 case 'x':
 640                         sigfile = optarg;
 641                         break;
 642                 default:
 643                         return usage(argv[0]);
 644                 }
 645         }
 646
 647         switch (cmd) {
 648         case CMD_APPEND:
 649                 if (certfile && sigfile)
 650                         return cert_append(certfile, sigfile);
 651                 else
 652                         return usage(argv[0]);
 653         case CMD_DUMP:
 654                 if (certfile)
 655                         return cert_dump(certfile);
 656                 else
 657                         return usage(argv[0]);
 658         case CMD_ISSUE:
 659                 if (certfile && pubkeyfile && seckeyfile)
 660                         return cert_issue(certfile, pubkeyfile, seckeyfile);
 661                 else
 662                         return usage(argv[0]);
 663         case CMD_REVOKE:
 664                 if (certfile && pubkeydir)
 665                         return cert_process_revoker(certfile, pubkeydir);
 666                 else
 667                         return usage(argv[0]);
 668         case CMD_VERIFY:
 669                 if (certfile && (pubkeyfile || pubkeydir))
 670                         return cert_verify(certfile, pubkeyfile, pubkeydir, msgfile);
 671                 else
 672                         return usage(argv[0]);
 673         case CMD_NONE:
 674                 return usage(argv[0]);
 675         }
 676
 677         /* unreachable */
 678         return usage(argv[0]);
 679 }