http.c

   1 /*
   2  * OpenConnect (SSL + DTLS) VPN client
   3  *
   4  * Copyright © 2008 Intel Corporation.
   5  * Copyright © 2008 Nick Andrew <nick@nick-andrew.net>
   6  *
   7  * Author: David Woodhouse <dwmw2@infradead.org>
   8  *
   9  * This program is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU Lesser General Public License
  11  * version 2.1, as published by the Free Software Foundation.
  12  *
  13  * This program is distributed in the hope that it will be useful, but
  14  * WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with this library; if not, write to:
  20  *
  21  *   Free Software Foundation, Inc.
  22  *   51 Franklin Street, Fifth Floor,
  23  *   Boston, MA 02110-1301 USA
  24  */
  25
  26 #define _GNU_SOURCE
  27 #include <netdb.h>
  28 #include <unistd.h>
  29 #include <fcntl.h>
  30 #include <time.h>
  31 #include <string.h>
  32 #include <ctype.h>
  33 #include <sys/stat.h>
  34
  35 #include <openssl/ssl.h>
  36 #include <openssl/err.h>
  37 #include <openssl/engine.h>
  38
  39 #include "openconnect.h"
  40
  41 #define MAX_BUF_LEN 131072
  42 /*
  43  * We didn't really want to have to do this for ourselves -- one might have
  44  * thought that it would be available in a library somewhere. But neither
  45  * cURL nor Neon have reliable cross-platform ways of either using a cert
  46  * from the TPM, or just reading from / writing to a transport which is
  47  * provided by their caller.
  48  */
  49
  50 static int process_http_response(struct openconnect_info *vpninfo, int *result,
  51                                  int (*header_cb)(struct openconnect_info *, char *, char *),
  52                                  char *body, int buf_len)
  53 {
  54         char buf[MAX_BUF_LEN];
  55         int bodylen = 0;
  56         int done = 0;
  57         int http10 = 0, closeconn = 0;
  58         int i;
  59
  60         if (openconnect_SSL_gets(vpninfo->https_ssl, buf, sizeof(buf)) < 0) {
  61                 vpninfo->progress(vpninfo, PRG_ERR, "Error fetching HTTPS response\n");
  62                 return -EINVAL;
  63         }
  64
  65  cont:
  66         if (!strncmp(buf, "HTTP/1.0 ", 9)) {
  67                 http10 = 1;
  68                 closeconn = 1;
  69         }
  70
  71         if ((!http10 && strncmp(buf, "HTTP/1.1 ", 9)) || !(*result = atoi(buf+9))) {
  72                 vpninfo->progress(vpninfo, PRG_ERR, "Failed to parse HTTP response '%s'\n", buf);
  73                 return -EINVAL;
  74         }
  75
  76         vpninfo->progress(vpninfo, PRG_TRACE, "Got HTTP response: %s\n", buf);
  77
  78         /* Eat headers... */
  79         while ((i = openconnect_SSL_gets(vpninfo->https_ssl, buf, sizeof(buf)))) {
  80                 char *colon;
  81
  82                 vpninfo->progress(vpninfo, PRG_TRACE, "%s\n", buf);
  83
  84                 if (i < 0) {
  85                         vpninfo->progress(vpninfo, PRG_ERR, "Error processing HTTP response\n");
  86                         return -EINVAL;
  87                 }
  88                 colon = strchr(buf, ':');
  89                 if (!colon) {
  90                         vpninfo->progress(vpninfo, PRG_ERR, "Ignoring unknown HTTP response line '%s'\n", buf);
  91                         continue;
  92                 }
  93                 *(colon++) = 0;
  94                 if (*colon == ' ')
  95                         colon++;
  96
  97                 if (!strcmp(buf, "Connection") && !strcmp(colon, "Close"))
  98                         closeconn = 1;
  99
 100                 if (!strcmp(buf, "Location")) {
 101                         vpninfo->redirect_url = strdup(colon);
 102                         if (!vpninfo->redirect_url)
 103                                 return -ENOMEM;
 104                 }
 105                 if (!strcmp(buf, "Content-Length")) {
 106                         bodylen = atoi(colon);
 107                         if (bodylen < 0 || bodylen > buf_len) {
 108                                 vpninfo->progress(vpninfo, PRG_ERR, "Response body too large for buffer (%d > %d)\n",
 109                                         bodylen, buf_len);
 110                                 return -EINVAL;
 111                         }
 112                 }
 113                 if (!strcmp(buf, "Set-Cookie")) {
 114                         struct vpn_option *new, **this;
 115                         char *semicolon = strchr(colon, ';');
 116                         char *equals = strchr(colon, '=');
 117
 118                         if (semicolon)
 119                                 *semicolon = 0;
 120
 121                         if (!equals) {
 122                                 vpninfo->progress(vpninfo, PRG_ERR, "Invalid cookie offered: %s\n", buf);
 123                                 return -EINVAL;
 124                         }
 125                         *(equals++) = 0;
 126
 127                         if (*equals) {
 128                                 new = malloc(sizeof(*new));
 129                                 if (!new) {
 130                                         vpninfo->progress(vpninfo, PRG_ERR, "No memory for allocating cookies\n");
 131                                         return -ENOMEM;
 132                                 }
 133                                 new->next = NULL;
 134                                 new->option = strdup(colon);
 135                                 new->value = strdup(equals);
 136                         } else {
 137                                 /* Kill cookie; don't replace it */
 138                                 new = NULL;
 139                         }
 140                         for (this = &vpninfo->cookies; *this; this = &(*this)->next) {
 141                                 if (!strcmp(colon, (*this)->option)) {
 142                                         /* Replace existing cookie */
 143                                         if (new)
 144                                                 new->next = (*this)->next;
 145                                         else
 146                                                 new = (*this)->next;
 147
 148                                         free((*this)->option);
 149                                         free((*this)->value);
 150                                         free(*this);
 151                                         *this = new;
 152                                         break;
 153                                 }
 154                         }
 155                         if (new && !*this) {
 156                                 *this = new;
 157                                 new->next = NULL;
 158                         }
 159                 }
 160                 if (!strcmp(buf, "Transfer-Encoding")) {
 161                         if (!strcmp(colon, "chunked"))
 162                                 bodylen = -1;
 163                         else {
 164                                 vpninfo->progress(vpninfo, PRG_ERR, "Unknown Transfer-Encoding: %s\n", colon);
 165                                 return -EINVAL;
 166                         }
 167                 }
 168                 if (header_cb && !strncmp(buf, "X-", 2))
 169                         header_cb(vpninfo, buf, colon);
 170         }
 171
 172         /* Handle 'HTTP/1.1 100 Continue'. Not that we should ever see it */
 173         if (*result == 100)
 174                 goto cont;
 175
 176         /* Now the body, if there is one */
 177         if (!bodylen)
 178                 goto fin;
 179
 180         if (http10) {
 181                 /* HTTP 1.0 response. Just eat all we can. */
 182                 while (1) {
 183                         i = SSL_read(vpninfo->https_ssl, body + done, bodylen - done);
 184                         if (i < 0)
 185                                 goto fin;
 186                         done += i;
 187                 }
 188         }
 189         /* If we were given Content-Length, it's nice and easy... */
 190         if (bodylen > 0) {
 191                 while (done < bodylen) {
 192                         i = SSL_read(vpninfo->https_ssl, body + done, bodylen - done);
 193                         if (i < 0) {
 194                                 vpninfo->progress(vpninfo, PRG_ERR, "Error reading HTTP response body\n");
 195                                 return -EINVAL;
 196                         }
 197                         done += i;
 198                 }
 199                 goto fin;
 200         }
 201
 202         /* ... else, chunked */
 203         while ((i = openconnect_SSL_gets(vpninfo->https_ssl, buf, sizeof(buf)))) {
 204                 int chunklen, lastchunk = 0;
 205
 206                 if (i < 0) {
 207                         vpninfo->progress(vpninfo, PRG_ERR, "Error fetching chunk header\n");
 208                         exit(1);
 209                 }
 210                 chunklen = strtol(buf, NULL, 16);
 211                 if (!chunklen) {
 212                         lastchunk = 1;
 213                         goto skip;
 214                 }
 215                 if (chunklen + done > buf_len) {
 216                         vpninfo->progress(vpninfo, PRG_ERR, "Response body too large for buffer (%d > %d)\n",
 217                                 chunklen + done, buf_len);
 218                         return -EINVAL;
 219                 }
 220                 while (chunklen) {
 221                         i = SSL_read(vpninfo->https_ssl, body + done, chunklen);
 222                         if (i < 0) {
 223                                 vpninfo->progress(vpninfo, PRG_ERR, "Error reading HTTP response body\n");
 224                                 return -EINVAL;
 225                         }
 226                         chunklen -= i;
 227                         done += i;
 228                 }
 229         skip:
 230                 if ((i = openconnect_SSL_gets(vpninfo->https_ssl, buf, sizeof(buf)))) {
 231                         if (i < 0) {
 232                                 vpninfo->progress(vpninfo, PRG_ERR, "Error fetching HTTP response body\n");
 233                         } else {
 234                                 vpninfo->progress(vpninfo, PRG_ERR, "Error in chunked decoding. Expected '', got: '%s'",
 235                                         buf);
 236                         }
 237                         return -EINVAL;
 238                 }
 239
 240                 if (lastchunk)
 241                         break;
 242         }
 243  fin:
 244         if (closeconn) {
 245                 SSL_free(vpninfo->https_ssl);
 246                 vpninfo->https_ssl = NULL;
 247                 close(vpninfo->ssl_fd);
 248                 vpninfo->ssl_fd = -1;
 249         }
 250         body[done] = 0;
 251         return done;
 252 }
 253
 254 static int fetch_config(struct openconnect_info *vpninfo, char *fu, char *bu,
 255                         char *server_sha1)
 256 {
 257         struct vpn_option *opt;
 258         char buf[MAX_BUF_LEN];
 259         int result, buflen;
 260         unsigned char local_sha1_bin[SHA_DIGEST_LENGTH];
 261         char local_sha1_ascii[(SHA_DIGEST_LENGTH * 2)+1];
 262         EVP_MD_CTX c;
 263         int i;
 264
 265         sprintf(buf, "GET %s%s HTTP/1.1\r\n", fu, bu);
 266         sprintf(buf + strlen(buf), "Host: %s\r\n", vpninfo->hostname);
 267         sprintf(buf + strlen(buf),  "User-Agent: %s\r\n", vpninfo->useragent);
 268         sprintf(buf + strlen(buf),  "Accept: */*\r\n");
 269         sprintf(buf + strlen(buf),  "Accept-Encoding: identity\r\n");
 270
 271         if (vpninfo->cookies) {
 272                 sprintf(buf + strlen(buf),  "Cookie: ");
 273                 for (opt = vpninfo->cookies; opt; opt = opt->next)
 274                         sprintf(buf + strlen(buf),  "%s=%s%s", opt->option,
 275                                       opt->value, opt->next ? "; " : "\r\n");
 276         }
 277         sprintf(buf + strlen(buf),  "X-Transcend-Version: 1\r\n\r\n");
 278
 279         SSL_write(vpninfo->https_ssl, buf, strlen(buf));
 280
 281         buflen = process_http_response(vpninfo, &result, NULL, buf, MAX_BUF_LEN);
 282         if (buflen < 0) {
 283                 /* We'll already have complained about whatever offended us */
 284                 return -EINVAL;
 285         }
 286
 287         if (result != 200)
 288                 return -EINVAL;
 289
 290
 291         EVP_MD_CTX_init(&c);
 292         EVP_Digest(buf, buflen, local_sha1_bin, NULL, EVP_sha1(), NULL);
 293         EVP_MD_CTX_cleanup(&c);
 294
 295         for (i = 0; i < SHA_DIGEST_LENGTH; i++)
 296                 sprintf(&local_sha1_ascii[i*2], "%02x", local_sha1_bin[i]);
 297
 298         if (strcasecmp(server_sha1, local_sha1_ascii)) {
 299                 vpninfo->progress(vpninfo, PRG_ERR, "Downloaded config file did not match intended SHA1\n");
 300                 return -EINVAL;
 301         }
 302
 303         return vpninfo->write_new_config(vpninfo, buf, buflen);
 304 }
 305
 306 static int run_csd_script(struct openconnect_info *vpninfo, char *buf, int buflen)
 307 {
 308         char fname[16];
 309         int fd;
 310
 311         sprintf(fname, "/tmp/csdXXXXXX");
 312         fd = mkstemp(fname);
 313         if (fd < 0) {
 314                 int err = -errno;
 315                 vpninfo->progress(vpninfo, PRG_ERR, "Failed to open temporary CSD script file: %s\n",
 316                                   strerror(errno));
 317                 return err;
 318         }
 319         write(fd, buf, buflen);
 320         fchmod(fd, 0700);
 321         close(fd);
 322
 323         if (!fork()) {
 324                 /* FIXME: Add whatever arguments we need */
 325                 system(fname);
 326                 vpninfo->progress(vpninfo, PRG_ERR, "Failed to exec CSD script %s\n", fname);
 327                 exit(1);
 328         }
 329
 330         free(vpninfo->csd_stuburl);
 331         vpninfo->csd_stuburl = NULL;
 332         vpninfo->urlpath = strdup(vpninfo->csd_waiturl +
 333                                   (vpninfo->csd_waiturl[0] == '/' ? 1 : 0));
 334         vpninfo->csd_waiturl = NULL;
 335         vpninfo->csd_scriptname = strdup(fname);
 336         return 0;
 337 }
 338
 339 /* Return value:
 340  *  < 0, on error
 341  *  = 0, no cookie (user cancel)
 342  *  = 1, obtained cookie
 343  */
 344 int openconnect_obtain_cookie(struct openconnect_info *vpninfo)
 345 {
 346         struct vpn_option *opt, *next;
 347         char buf[MAX_BUF_LEN];
 348         int result, buflen;
 349         char request_body[2048];
 350         char *request_body_type = NULL;
 351         char *method = "GET";
 352
 353  retry:
 354         if (!vpninfo->https_ssl && openconnect_open_https(vpninfo)) {
 355                 vpninfo->progress(vpninfo, PRG_ERR, "Failed to open HTTPS connection to %s\n",
 356                         vpninfo->hostname);
 357                 return -EINVAL;
 358         }
 359
 360         /*
 361          * It would be nice to use cURL for this, but we really need to guarantee
 362          * that we'll be using OpenSSL (for the TPM stuff), and it doesn't seem
 363          * to have any way to let us provide our own socket read/write functions.
 364          * We can only provide a socket _open_ function. Which would require having
 365          * a socketpair() and servicing the "other" end of it.
 366          *
 367          * So we process the HTTP for ourselves...
 368          */
 369         sprintf(buf, "%s /%s HTTP/1.1\r\n", method, vpninfo->urlpath ?: "");
 370         sprintf(buf + strlen(buf), "Host: %s\r\n", vpninfo->hostname);
 371         sprintf(buf + strlen(buf),  "User-Agent: %s\r\n", vpninfo->useragent);
 372         sprintf(buf + strlen(buf),  "Accept: */*\r\n");
 373         sprintf(buf + strlen(buf),  "Accept-Encoding: identity\r\n");
 374
 375         if (vpninfo->cookies) {
 376                 sprintf(buf + strlen(buf),  "Cookie: ");
 377                 for (opt = vpninfo->cookies; opt; opt = opt->next)
 378                         sprintf(buf + strlen(buf),  "%s=%s%s", opt->option,
 379                                       opt->value, opt->next ? "; " : "\r\n");
 380         }
 381         if (request_body_type) {
 382                 sprintf(buf + strlen(buf),  "Content-Type: %s\r\n",
 383                               request_body_type);
 384                 sprintf(buf + strlen(buf),  "Content-Length: %zd\r\n",
 385                               strlen(request_body));
 386         }
 387         sprintf(buf + strlen(buf),  "X-Transcend-Version: 1\r\n\r\n");
 388         if (request_body_type)
 389                 sprintf(buf + strlen(buf), "%s", request_body);
 390
 391         vpninfo->progress(vpninfo, PRG_INFO, "%s %s/%s\n", method,
 392                           vpninfo->hostname, vpninfo->urlpath ?: "");
 393
 394         SSL_write(vpninfo->https_ssl, buf, strlen(buf));
 395
 396         buflen = process_http_response(vpninfo, &result, NULL, buf, MAX_BUF_LEN);
 397         if (buflen < 0) {
 398                 /* We'll already have complained about whatever offended us */
 399                 exit(1);
 400         }
 401
 402         if (result != 200 && vpninfo->redirect_url) {
 403         redirect:
 404                 if (!strncmp(vpninfo->redirect_url, "https://", 8)) {
 405                         /* New host. Tear down the existing connection and make a new one */
 406                         char *host = vpninfo->redirect_url + 8;
 407                         char *path = strchr(host, '/');
 408
 409                         free(vpninfo->urlpath);
 410                         if (path) {
 411                                 *(path++) = 0;
 412                                 vpninfo->urlpath = strdup(path);
 413                         } else
 414                                 vpninfo->urlpath = NULL;
 415
 416                         if (strcmp(vpninfo->hostname, host)) {
 417                                 free(vpninfo->hostname);
 418                                 vpninfo->hostname = strdup(host);
 419
 420                                 /* Kill the existing connection, and a new one will happen */
 421                                 SSL_free(vpninfo->https_ssl);
 422                                 vpninfo->https_ssl = NULL;
 423                                 close(vpninfo->ssl_fd);
 424                                 vpninfo->ssl_fd = -1;
 425
 426                                 for (opt = vpninfo->cookies; opt; opt = next) {
 427                                         next = opt->next;
 428
 429                                         free(opt->option);
 430                                         free(opt->value);
 431                                         free(opt);
 432                                 }
 433                                 vpninfo->cookies = NULL;
 434                         }
 435                         free(vpninfo->redirect_url);
 436                         vpninfo->redirect_url = NULL;
 437
 438                         goto retry;
 439                 } else if (vpninfo->redirect_url[0] == '/') {
 440                         /* Absolute redirect within same host */
 441                         free(vpninfo->urlpath);
 442                         vpninfo->urlpath = strdup(vpninfo->redirect_url + 1);
 443                         free(vpninfo->redirect_url);
 444                         vpninfo->redirect_url = NULL;
 445                         goto retry;
 446                 } else {
 447                         vpninfo->progress(vpninfo, PRG_ERR, "Relative redirect (to '%s') not supported\n",
 448                                 vpninfo->redirect_url);
 449                         return -EINVAL;
 450                 }
 451         }
 452
 453         if (vpninfo->csd_stuburl) {
 454                 /* This is the CSD stub script, which we now need to run */
 455                 result = run_csd_script(vpninfo, buf, buflen);
 456                 if (result)
 457                         return result;
 458
 459                 /* Now we'll be redirected to the waiturl */
 460                 goto retry;
 461         }
 462         if (strncmp(buf, "<?xml", 5)) {
 463                 /* Not XML? Perhaps it's HTML with a refresh... */
 464                 if (strcasestr(buf, "http-equiv=\"refresh\"")) {
 465                         vpninfo->progress(vpninfo, PRG_INFO, "Refreshing %s after 1 second...\n",
 466                                           vpninfo->urlpath);
 467                         sleep(1);
 468                         goto retry;
 469                 }
 470                 vpninfo->progress(vpninfo, PRG_ERR, "Unknown response from server\n");
 471                 return -EINVAL;
 472         }
 473         request_body[0] = 0;
 474         result = parse_xml_response(vpninfo, buf, request_body, sizeof(request_body),
 475                                     &method, &request_body_type);
 476         if (!result)
 477                 goto redirect;
 478
 479         if (result != 2)
 480                 return result;
 481         /* A return value of 2 means the XML form indicated
 482            success. We _should_ have a cookie... */
 483
 484         for (opt = vpninfo->cookies; opt; opt = opt->next) {
 485
 486                 if (!strcmp(opt->option, "webvpn"))
 487                         vpninfo->cookie = opt->value;
 488                 else if (vpninfo->write_new_config && !strcmp(opt->option, "webvpnc")) {
 489                         char *tok = opt->value;
 490                         char *bu = NULL, *fu = NULL, *sha = NULL;
 491
 492                         do {
 493                                 if (tok != opt->value)
 494                                         *(tok++) = 0;
 495
 496                                 if (!strncmp(tok, "bu:", 3))
 497                                         bu = tok + 3;
 498                                 else if (!strncmp(tok, "fu:", 3))
 499                                         fu = tok + 3;
 500                                 else if (!strncmp(tok, "fh:", 3)) {
 501                                         if (!strncasecmp(tok+3, vpninfo->xmlsha1,
 502                                                          SHA_DIGEST_LENGTH * 2))
 503                                                 break;
 504                                         sha = tok + 3;
 505                                 }
 506                         } while ((tok = strchr(tok, '&')));
 507
 508                         if (bu && fu && sha)
 509                                 fetch_config(vpninfo, bu, fu, sha);
 510                 }
 511         }
 512         if (vpninfo->csd_scriptname) {
 513                 unlink(vpninfo->csd_scriptname);
 514                 free(vpninfo->csd_scriptname);
 515                 vpninfo->csd_scriptname = NULL;
 516         }
 517         return 0;
 518 }
 519
 520 char *openconnect_create_useragent(char *base)
 521 {
 522         char *uagent = malloc(strlen(base) + 1 + strlen(openconnect_version));
 523         sprintf(uagent, "%s%s", base, openconnect_version);
 524         return uagent;
 525 }