citadel/modules/openid/serv_openid_rp.c

   1 /*
   2  * $Id$
   3  *
   4  * OpenID 1.1 "relying party" implementation
   5  *
   6  */
   7
   8 #include "sysdep.h"
   9 #include <stdlib.h>
  10 #include <unistd.h>
  11 #include <stdio.h>
  12 #include <fcntl.h>
  13 #include <signal.h>
  14 #include <pwd.h>
  15 #include <errno.h>
  16 #include <sys/types.h>
  17
  18 #if TIME_WITH_SYS_TIME
  19 # include <sys/time.h>
  20 # include <time.h>
  21 #else
  22 # if HAVE_SYS_TIME_H
  23 #  include <sys/time.h>
  24 # else
  25 #  include <time.h>
  26 # endif
  27 #endif
  28
  29 #include <sys/wait.h>
  30 #include <string.h>
  31 #include <limits.h>
  32 #include <curl/curl.h>
  33 #include "ctdl_module.h"
  34
  35
  36 struct associate_handle {
  37         char claimed_id[256];
  38         char assoc_type[32];
  39         time_t expiration_time;
  40         char assoc_handle[128];
  41         char mac_key[128];
  42 };
  43
  44 HashList *HL = NULL;            // hash table of assoc_handle
  45
  46 /*
  47  * Locate a <link> tag and, given its 'rel=' parameter, return its 'href' parameter
  48  */
  49 void extract_link(char *target_buf, int target_size, char *rel, char *source_buf)
  50 {
  51         char *ptr = source_buf;
  52
  53         if (!target_buf) return;
  54         if (!rel) return;
  55         if (!source_buf) return;
  56
  57         target_buf[0] = 0;
  58
  59         while (ptr = bmstrcasestr(ptr, "<link"), ptr != NULL) {
  60
  61                 char work_buffer[1024];
  62                 char *link_tag_start = NULL;
  63                 char *link_tag_end = NULL;
  64
  65                 char rel_tag[1024];
  66                 char href_tag[1024];
  67
  68                 link_tag_start = ptr;
  69                 link_tag_end = strchr(ptr, '>');
  70                 rel_tag[0] = 0;
  71                 href_tag[0] = 0;
  72
  73                 if ((link_tag_end) && (link_tag_end > link_tag_start)) {
  74                         int len;
  75                         len = link_tag_end - link_tag_start;
  76                         if (len > sizeof work_buffer) len = sizeof work_buffer;
  77                         memcpy(work_buffer, link_tag_start, len);
  78
  79                         char *rel_start = NULL;
  80                         char *rel_end = NULL;
  81                         rel_start = bmstrcasestr(work_buffer, "rel=");
  82                         if (rel_start) {
  83                                 rel_start = strchr(rel_start, '\"');
  84                                 if (rel_start) {
  85                                         ++rel_start;
  86                                         rel_end = strchr(rel_start, '\"');
  87                                         if ((rel_end) && (rel_end > rel_start)) {
  88                                                 safestrncpy(rel_tag, rel_start, rel_end - rel_start + 1);
  89                                         }
  90                                 }
  91                         }
  92
  93                         char *href_start = NULL;
  94                         char *href_end = NULL;
  95                         href_start = bmstrcasestr(work_buffer, "href=");
  96                         if (href_start) {
  97                                 href_start = strchr(href_start, '\"');
  98                                 if (href_start) {
  99                                         ++href_start;
 100                                         href_end = strchr(href_start, '\"');
 101                                         if ((href_end) && (href_end > href_start)) {
 102                                                 safestrncpy(href_tag, href_start, href_end - href_start + 1);
 103                                         }
 104                                 }
 105                         }
 106
 107                         if (!strcasecmp(rel, rel_tag)) {
 108                                 safestrncpy(target_buf, href_tag, target_size);
 109                                 return;
 110                         }
 111
 112                 }
 113
 114         ++ptr;
 115         }
 116
 117
 118 }
 119
 120
 121
 122 struct fh_data {
 123         char *buf;
 124         int total_bytes_received;
 125         int maxbytes;
 126 };
 127
 128
 129 size_t fh_callback(void *ptr, size_t size, size_t nmemb, void *stream)
 130 {
 131         struct fh_data *fh = (struct fh_data *) stream;
 132         int got_bytes = (size * nmemb);
 133
 134         if (fh->total_bytes_received + got_bytes > fh->maxbytes) {
 135                 got_bytes = fh->maxbytes - fh->total_bytes_received;
 136         }
 137         if (got_bytes > 0) {
 138                 memcpy(&fh->buf[fh->total_bytes_received], ptr, got_bytes);
 139                 fh->total_bytes_received += got_bytes;
 140         }
 141
 142         return got_bytes;
 143 }
 144
 145
 146
 147 /*
 148  * Begin an HTTP fetch (returns number of bytes actually fetched, or -1 for error)
 149  * We first try 'curl' or 'wget' because they have more robust HTTP handling, and also
 150  * support HTTPS.  If neither one works, we fall back to a built in mini HTTP client.
 151  */
 152 int fetch_http(char *url, char *target_buf, int maxbytes)
 153 {
 154         CURL *curl;
 155         CURLcode res;
 156         char errmsg[1024] = "";
 157         struct fh_data fh = {
 158                 target_buf,
 159                 0,
 160                 maxbytes
 161         };
 162
 163         if (!url) return(-1);
 164         if (!target_buf) return(-1);
 165         memset(target_buf, 0, maxbytes);
 166
 167         curl = curl_easy_init();
 168         if (!curl) {
 169                 CtdlLogPrintf(CTDL_ALERT, "Unable to initialize libcurl.\n");
 170                 return(-1);
 171         }
 172
 173         curl_easy_setopt(curl, CURLOPT_URL, url);
 174         curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, 0);
 175         curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, 0);
 176         curl_easy_setopt(curl, CURLOPT_WRITEDATA, &fh);
 177         curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, fh_callback);
 178         curl_easy_setopt(curl, CURLOPT_ERRORBUFFER, errmsg);
 179         curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1);
 180         res = curl_easy_perform(curl);
 181         curl_easy_cleanup(curl);
 182         return fh.total_bytes_received;
 183 }
 184
 185
 186 #define ASSOCIATE_RESPONSE_SIZE 4096
 187
 188 /*
 189  * libcurl callback function for prepare_openid_associate_request()
 190  */
 191 size_t associate_callback(void *ptr, size_t size, size_t nmemb, void *stream)
 192 {
 193         char *response = (char *) stream;
 194         int got_bytes = (size * nmemb);
 195         int len = strlen(response);
 196
 197         if ((len + got_bytes + 1) < ASSOCIATE_RESPONSE_SIZE) {
 198                 memcpy(&response[len], ptr, got_bytes);
 199                 response[len+got_bytes] = 0;
 200         }
 201
 202         return got_bytes;
 203 }
 204
 205
 206 /*
 207  * Helper function for process_associate_response()
 208  * (Delete function for hash table)
 209  */
 210 void delete_assoc_handle(void *data) {
 211         if (data) free(data);
 212 }
 213
 214
 215 /*
 216  * Process the response from an "associate" request
 217  */
 218 struct associate_handle *process_associate_response(char *claimed_id, char *associate_response)
 219 {
 220         struct associate_handle *h = NULL;
 221         char *ptr = associate_response;
 222         char thisline[256];
 223         char thiskey[256];
 224         char thisdata[256];
 225
 226         h = (struct associate_handle *) malloc(sizeof(struct associate_handle));
 227         safestrncpy(h->claimed_id, claimed_id, sizeof h->claimed_id);
 228
 229         do {
 230                 ptr = memreadline(ptr, thisline, sizeof thisline);
 231                 extract_token(thiskey, thisline, 0, ':', sizeof thiskey);
 232                 extract_token(thisdata, thisline, 1, ':', sizeof thisdata);
 233
 234                 if (!strcasecmp(thiskey, "assoc_type")) {
 235                         safestrncpy(h->assoc_type, thisdata, sizeof h->assoc_type);
 236                 }
 237                 else if (!strcasecmp(thiskey, "expires_in")) {
 238                         h->expiration_time = time(NULL) + atol(thisdata);
 239                 }
 240                 else if (!strcasecmp(thiskey, "assoc_handle")) {
 241                         safestrncpy(h->assoc_handle, thisdata, sizeof h->assoc_handle);
 242                 }
 243                 else if (!strcasecmp(thiskey, "mac_key")) {
 244                         safestrncpy(h->mac_key, thisdata, sizeof h->mac_key);
 245                 }
 246
 247         } while (*ptr);
 248
 249         /* Add this data structure into the hash table */
 250         Put(HL, h->assoc_handle, strlen(h->assoc_handle), h, delete_assoc_handle);
 251
 252         /* FIXME periodically purge the hash table of expired handles */
 253
 254         return h;
 255 }
 256
 257
 258
 259 /*
 260  * Establish a shared secret with an OpenID Identity Provider by sending
 261  * an "associate" request.
 262  */
 263 struct associate_handle *prepare_openid_associate_request(
 264                 char *claimed_id, char *openid_server, char *openid_delegate)
 265 {
 266         CURL *curl;
 267         CURLcode res;
 268         struct curl_httppost *formpost=NULL;
 269         struct curl_httppost *lastptr=NULL;
 270         char associate_response[ASSOCIATE_RESPONSE_SIZE];
 271         struct associate_handle *h = NULL;
 272
 273         memset(associate_response, 0, ASSOCIATE_RESPONSE_SIZE);
 274
 275         curl_formadd(&formpost,
 276                         &lastptr,
 277                         CURLFORM_COPYNAME,      "openid.mode",
 278                         CURLFORM_COPYCONTENTS,  "associate",
 279                         CURLFORM_END
 280         );
 281
 282         curl_formadd(&formpost,
 283                         &lastptr,
 284                         CURLFORM_COPYNAME,      "openid.session_type",
 285                         CURLFORM_COPYCONTENTS,  "",
 286                         CURLFORM_END
 287         );
 288
 289         curl = curl_easy_init();
 290         if (curl) {
 291                 curl_easy_setopt(curl, CURLOPT_URL, openid_server);
 292                 curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, 0);
 293                 curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, 0);
 294                 curl_easy_setopt(curl, CURLOPT_WRITEDATA, associate_response);
 295                 curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, associate_callback);
 296                 curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1);
 297
 298                 curl_easy_setopt(curl, CURLOPT_HTTPPOST, formpost);
 299                 res = curl_easy_perform(curl);
 300                 h = process_associate_response(claimed_id, associate_response);
 301                 curl_easy_cleanup(curl);
 302         }
 303         curl_formfree(formpost);
 304
 305         return h;
 306 }
 307
 308
 309
 310
 311
 312 /*
 313  * Setup an OpenID authentication
 314  */
 315 void cmd_oids(char *argbuf) {
 316         char openid_url[1024];
 317         char return_to[1024];
 318         char trust_root[1024];
 319         int i;
 320         char buf[SIZ];
 321         struct associate_handle *h = NULL;
 322
 323         if (CC->logged_in) {
 324                 cprintf("%d Already logged in.\n", ERROR + ALREADY_LOGGED_IN);
 325                 return;
 326         }
 327
 328         extract_token(openid_url, argbuf, 0, '|', sizeof openid_url);
 329         extract_token(return_to, argbuf, 1, '|', sizeof return_to);
 330         extract_token(trust_root, argbuf, 2, '|', sizeof trust_root);
 331
 332         i = fetch_http(openid_url, buf, sizeof buf - 1);
 333         buf[sizeof buf - 1] = 0;
 334         if (i > 0) {
 335                 char openid_server[1024];
 336                 char openid_delegate[1024];
 337
 338                 extract_link(openid_server, sizeof openid_server, "openid.server", buf);
 339                 extract_link(openid_delegate, sizeof openid_delegate, "openid.delegate", buf);
 340
 341                 if (IsEmptyStr(openid_server)) {
 342                         cprintf("%d There is no OpenID identity provider at this URL.\n", ERROR);
 343                         return;
 344                 }
 345
 346                 /* Empty delegate is legal; we just use the openid_url instead */
 347                 if (IsEmptyStr(openid_delegate)) {
 348                         safestrncpy(openid_delegate, openid_url, sizeof openid_delegate);
 349                 }
 350
 351                 /*
 352                  * Prepare an "associate" request.  This contacts the IdP and fetches
 353                  * a data structure containing an assoc_handle plus a shared secret.
 354                  */
 355                 h = prepare_openid_associate_request(openid_url, openid_server, openid_delegate);
 356
 357                 /* Assemble a URL to which the user-agent will be redirected. */
 358                 char redirect_string[4096];
 359                 char escaped_identity[1024];
 360                 char escaped_return_to[1024];
 361                 char escaped_trust_root[1024];
 362                 char escaped_sreg_optional[256];
 363                 char escaped_assoc_handle[256];
 364
 365                 urlesc(escaped_identity, sizeof escaped_identity, openid_delegate);
 366                 urlesc(escaped_assoc_handle, sizeof escaped_assoc_handle, h->assoc_handle);
 367                 urlesc(escaped_return_to, sizeof escaped_return_to, return_to);
 368                 urlesc(escaped_trust_root, sizeof escaped_trust_root, trust_root);
 369                 urlesc(escaped_sreg_optional, sizeof escaped_sreg_optional,
 370                         "nickname,email,fullname,postcode,country");
 371
 372                 snprintf(redirect_string, sizeof redirect_string,
 373                         "%s"
 374                         "?openid.mode=checkid_setup"
 375                         "&openid.identity=%s"
 376                         "&openid.assoc_handle=%s"
 377                         "&openid.return_to=%s"
 378                         "&openid.trust_root=%s"
 379                         "&openid.sreg.optional=%s"
 380                         ,
 381                         openid_server,
 382                         escaped_identity,
 383                         escaped_assoc_handle,
 384                         escaped_return_to,
 385                         escaped_trust_root,
 386                         escaped_sreg_optional
 387                 );
 388                 CtdlLogPrintf(CTDL_DEBUG, "Telling client about assoc_handle <%s>\n", h->assoc_handle);
 389                 cprintf("%d %s\n", CIT_OK, redirect_string);
 390                 return;
 391         }
 392
 393         cprintf("%d Unable to fetch OpenID URL\n", ERROR);
 394 }
 395
 396
 397
 398 /*
 399  * Finalize an OpenID authentication
 400  */
 401 void cmd_oidf(char *argbuf) {
 402         char assoc_handle[256];
 403         struct associate_handle *h = NULL;
 404
 405         extract_token(assoc_handle, argbuf, 0, '|', sizeof assoc_handle);
 406
 407         if (GetHash(HL, assoc_handle, strlen(assoc_handle), (void *)&h)) {
 408                 cprintf("%d handle %s is good\n", CIT_OK, assoc_handle);
 409
 410                 // FIXME now do something with it
 411
 412         }
 413         else {
 414                 cprintf("%d handle %s not found\n", ERROR, assoc_handle);
 415         }
 416 }
 417
 418
 419
 420
 421 CTDL_MODULE_INIT(openid_rp)
 422 {
 423         if (!threading)
 424         {
 425                 curl_global_init(CURL_GLOBAL_ALL);
 426                 HL = NewHash(1, NULL);
 427                 CtdlRegisterProtoHook(cmd_oids, "OIDS", "Setup OpenID authentication");
 428                 CtdlRegisterProtoHook(cmd_oidf, "OIDF", "Finalize OpenID authentication");
 429         }
 430
 431         /* return our Subversion id for the Log */
 432         return "$Id$";
 433 }