package/uhttpd/src/uhttpd-cgi.c

   1 /*
   2  * uhttpd - Tiny single-threaded httpd - CGI handler
   3  *
   4  *   Copyright (C) 2010 Jo-Philipp Wich <xm@subsignal.org>
   5  *
   6  *  Licensed under the Apache License, Version 2.0 (the "License");
   7  *  you may not use this file except in compliance with the License.
   8  *  You may obtain a copy of the License at
   9  *
  10  *      http://www.apache.org/licenses/LICENSE-2.0
  11  *
  12  *  Unless required by applicable law or agreed to in writing, software
  13  *  distributed under the License is distributed on an "AS IS" BASIS,
  14  *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  15  *  See the License for the specific language governing permissions and
  16  *  limitations under the License.
  17  */
  18
  19 #include "uhttpd.h"
  20 #include "uhttpd-utils.h"
  21 #include "uhttpd-cgi.h"
  22
  23 static struct http_response * uh_cgi_header_parse(char *buf, int len, int *off)
  24 {
  25         char *bufptr = NULL;
  26         char *hdrname = NULL;
  27         int hdrcount = 0;
  28         int pos = 0;
  29
  30         static struct http_response res;
  31
  32
  33         if( ((bufptr = strfind(buf, len, "\r\n\r\n", 4)) != NULL) ||
  34             ((bufptr = strfind(buf, len, "\n\n", 2)) != NULL)
  35         ) {
  36                 *off = (int)(bufptr - buf) + ((bufptr[0] == '\r') ? 4 : 2);
  37
  38                 memset(&res, 0, sizeof(res));
  39
  40                 res.statuscode = 200;
  41                 res.statusmsg  = "OK";
  42
  43                 bufptr = &buf[0];
  44
  45                 for( pos = 0; pos < len; pos++ )
  46                 {
  47                         if( !hdrname && (buf[pos] == ':') )
  48                         {
  49                                 buf[pos++] = 0;
  50
  51                                 if( (pos < len) && (buf[pos] == ' ') )
  52                                         pos++;
  53
  54                                 if( pos < len )
  55                                 {
  56                                         hdrname = bufptr;
  57                                         bufptr = &buf[pos];
  58                                 }
  59                         }
  60
  61                         else if( (buf[pos] == '\r') || (buf[pos] == '\n') )
  62                         {
  63                                 buf[pos++] = 0;
  64
  65                                 if( ! hdrname )
  66                                         break;
  67
  68                                 if( (pos < len) && (buf[pos] == '\n') )
  69                                         pos++;
  70
  71                                 if( pos < len )
  72                                 {
  73                                         if( (hdrcount + 1) < array_size(res.headers) )
  74                                         {
  75                                                 if( ! strcasecmp(hdrname, "Status") )
  76                                                 {
  77                                                         res.statuscode = atoi(bufptr);
  78
  79                                                         if( res.statuscode < 100 )
  80                                                                 res.statuscode = 200;
  81
  82                                                         if( ((bufptr = strchr(bufptr, ' ')) != NULL) && (&bufptr[1] != 0) )
  83                                                                 res.statusmsg = &bufptr[1];
  84                                                 }
  85                                                 else
  86                                                 {
  87                                                         res.headers[hdrcount++] = hdrname;
  88                                                         res.headers[hdrcount++] = bufptr;
  89                                                 }
  90
  91                                                 bufptr = &buf[pos];
  92                                                 hdrname = NULL;
  93                                         }
  94                                         else
  95                                         {
  96                                                 return NULL;
  97                                         }
  98                                 }
  99                         }
 100                 }
 101
 102                 return &res;
 103         }
 104
 105         return NULL;
 106 }
 107
 108 static char * uh_cgi_header_lookup(struct http_response *res, const char *hdrname)
 109 {
 110         int i;
 111
 112         foreach_header(i, res->headers)
 113         {
 114                 if( ! strcasecmp(res->headers[i], hdrname) )
 115                         return res->headers[i+1];
 116         }
 117
 118         return NULL;
 119 }
 120
 121 static int uh_cgi_error_500(struct client *cl, struct http_request *req, const char *message)
 122 {
 123         if( uh_http_sendf(cl, NULL,
 124                 "HTTP/%.1f 500 Internal Server Error\r\n"
 125                 "Content-Type: text/plain\r\n%s\r\n",
 126                         req->version,
 127                         (req->version > 1.0)
 128                                 ? "Transfer-Encoding: chunked\r\n" : ""
 129                 ) >= 0
 130         ) {
 131                 return uh_http_send(cl, req, message, -1);
 132         }
 133
 134         return -1;
 135 }
 136
 137
 138 void uh_cgi_request(struct client *cl, struct http_request *req, struct path_info *pi)
 139 {
 140         int i, hdroff, bufoff;
 141         int hdrlen = 0;
 142         int buflen = 0;
 143         int fd_max = 0;
 144         int content_length = 0;
 145         int header_sent = 0;
 146
 147         int rfd[2] = { 0, 0 };
 148         int wfd[2] = { 0, 0 };
 149
 150         char buf[UH_LIMIT_MSGHEAD];
 151         char hdr[UH_LIMIT_MSGHEAD];
 152
 153         pid_t child;
 154
 155         fd_set reader;
 156         fd_set writer;
 157
 158         struct sigaction sa;
 159         struct timeval timeout;
 160         struct http_response *res;
 161
 162
 163         /* spawn pipes for me->child, child->me */
 164         if( (pipe(rfd) < 0) || (pipe(wfd) < 0) )
 165         {
 166                 uh_http_sendhf(cl, 500, "Internal Server Error",
 167                         "Failed to create pipe: %s", strerror(errno));
 168
 169                 if( rfd[0] > 0 ) close(rfd[0]);
 170                 if( rfd[1] > 0 ) close(rfd[1]);
 171                 if( wfd[0] > 0 ) close(wfd[0]);
 172                 if( wfd[1] > 0 ) close(wfd[1]);
 173
 174                 return;
 175         }
 176
 177         /* fork off child process */
 178         switch( (child = fork()) )
 179         {
 180                 /* oops */
 181                 case -1:
 182                         uh_http_sendhf(cl, 500, "Internal Server Error",
 183                                 "Failed to fork child: %s", strerror(errno));
 184                         return;
 185
 186                 /* exec child */
 187                 case 0:
 188                         /* restore SIGTERM */
 189                         sa.sa_flags = 0;
 190                         sa.sa_handler = SIG_DFL;
 191                         sigemptyset(&sa.sa_mask);
 192                         sigaction(SIGTERM, &sa, NULL);
 193
 194                         /* close loose pipe ends */
 195                         close(rfd[0]);
 196                         close(wfd[1]);
 197
 198                         /* patch stdout and stdin to pipes */
 199                         dup2(rfd[1], 1);
 200                         dup2(wfd[0], 0);
 201
 202                         /* check for regular, world-executable file */
 203                         if( (pi->stat.st_mode & S_IFREG) &&
 204                             (pi->stat.st_mode & S_IXOTH)
 205                         ) {
 206                                 /* build environment */
 207                                 clearenv();
 208
 209                                 /* common information */
 210                                 setenv("GATEWAY_INTERFACE", "CGI/1.1", 1);
 211                                 setenv("SERVER_SOFTWARE", "uHTTPd", 1);
 212                                 setenv("PATH", "/sbin:/usr/sbin:/bin:/usr/bin", 1);
 213
 214 #ifdef HAVE_TLS
 215                                 /* https? */
 216                                 if( cl->tls )
 217                                         setenv("HTTPS", "on", 1);
 218 #endif
 219
 220                                 /* addresses */
 221                                 setenv("SERVER_NAME", sa_straddr(&cl->servaddr), 1);
 222                                 setenv("SERVER_ADDR", sa_straddr(&cl->servaddr), 1);
 223                                 setenv("SERVER_PORT", sa_strport(&cl->servaddr), 1);
 224                                 setenv("REMOTE_HOST", sa_straddr(&cl->peeraddr), 1);
 225                                 setenv("REMOTE_ADDR", sa_straddr(&cl->peeraddr), 1);
 226                                 setenv("REMOTE_PORT", sa_strport(&cl->peeraddr), 1);
 227
 228                                 /* path information */
 229                                 setenv("SCRIPT_NAME", pi->name, 1);
 230                                 setenv("SCRIPT_FILENAME", pi->phys, 1);
 231                                 setenv("DOCUMENT_ROOT", pi->root, 1);
 232                                 setenv("QUERY_STRING", pi->query ? pi->query : "", 1);
 233
 234                                 if( pi->info )
 235                                         setenv("PATH_INFO", pi->info, 1);
 236
 237
 238                                 /* http version */
 239                                 if( req->version > 1.0 )
 240                                         setenv("SERVER_PROTOCOL", "HTTP/1.1", 1);
 241                                 else
 242                                         setenv("SERVER_PROTOCOL", "HTTP/1.0", 1);
 243
 244                                 /* request method */
 245                                 switch( req->method )
 246                                 {
 247                                         case UH_HTTP_MSG_GET:
 248                                                 setenv("REQUEST_METHOD", "GET", 1);
 249                                                 break;
 250
 251                                         case UH_HTTP_MSG_HEAD:
 252                                                 setenv("REQUEST_METHOD", "HEAD", 1);
 253                                                 break;
 254
 255                                         case UH_HTTP_MSG_POST:
 256                                                 setenv("REQUEST_METHOD", "POST", 1);
 257                                                 break;
 258                                 }
 259
 260                                 /* request url */
 261                                 setenv("REQUEST_URI", req->url, 1);
 262
 263                                 /* remote user */
 264                                 if( req->realm )
 265                                         setenv("REMOTE_USER", req->realm->user, 1);
 266
 267                                 /* request message headers */
 268                                 foreach_header(i, req->headers)
 269                                 {
 270                                         if( ! strcasecmp(req->headers[i], "Accept") )
 271                                                 setenv("HTTP_ACCEPT", req->headers[i+1], 1);
 272
 273                                         else if( ! strcasecmp(req->headers[i], "Accept-Charset") )
 274                                                 setenv("HTTP_ACCEPT_CHARSET", req->headers[i+1], 1);
 275
 276                                         else if( ! strcasecmp(req->headers[i], "Accept-Encoding") )
 277                                                 setenv("HTTP_ACCEPT_ENCODING", req->headers[i+1], 1);
 278
 279                                         else if( ! strcasecmp(req->headers[i], "Accept-Language") )
 280                                                 setenv("HTTP_ACCEPT_LANGUAGE", req->headers[i+1], 1);
 281
 282                                         else if( ! strcasecmp(req->headers[i], "Authorization") )
 283                                                 setenv("HTTP_AUTHORIZATION", req->headers[i+1], 1);
 284
 285                                         else if( ! strcasecmp(req->headers[i], "Connection") )
 286                                                 setenv("HTTP_CONNECTION", req->headers[i+1], 1);
 287
 288                                         else if( ! strcasecmp(req->headers[i], "Cookie") )
 289                                                 setenv("HTTP_COOKIE", req->headers[i+1], 1);
 290
 291                                         else if( ! strcasecmp(req->headers[i], "Host") )
 292                                                 setenv("HTTP_HOST", req->headers[i+1], 1);
 293
 294                                         else if( ! strcasecmp(req->headers[i], "Referer") )
 295                                                 setenv("HTTP_REFERER", req->headers[i+1], 1);
 296
 297                                         else if( ! strcasecmp(req->headers[i], "User-Agent") )
 298                                                 setenv("HTTP_USER_AGENT", req->headers[i+1], 1);
 299
 300                                         else if( ! strcasecmp(req->headers[i], "Content-Type") )
 301                                                 setenv("CONTENT_TYPE", req->headers[i+1], 1);
 302
 303                                         else if( ! strcasecmp(req->headers[i], "Content-Length") )
 304                                                 setenv("CONTENT_LENGTH", req->headers[i+1], 1);
 305                                 }
 306
 307
 308                                 /* execute child code ... */
 309                                 if( chdir(pi->root) )
 310                                         perror("chdir()");
 311
 312                                 execl(pi->phys, pi->phys, NULL);
 313
 314                                 /* in case it fails ... */
 315                                 printf(
 316                                         "Status: 500 Internal Server Error\r\n\r\n"
 317                                         "Unable to launch the requested CGI program:\n"
 318                                         "  %s: %s\n",
 319                                                 pi->phys, strerror(errno)
 320                                 );
 321                         }
 322
 323                         /* 403 */
 324                         else
 325                         {
 326                                 printf(
 327                                         "Status: 403 Forbidden\r\n\r\n"
 328                                         "Access to this resource is forbidden\n"
 329                                 );
 330                         }
 331
 332                         close(wfd[0]);
 333                         close(rfd[1]);
 334                         exit(0);
 335
 336                         break;
 337
 338                 /* parent; handle I/O relaying */
 339                 default:
 340                         /* close unneeded pipe ends */
 341                         close(rfd[1]);
 342                         close(wfd[0]);
 343
 344                         /* max watch fd */
 345                         fd_max = max(rfd[0], wfd[1]) + 1;
 346
 347                         /* find content length */
 348                         if( req->method == UH_HTTP_MSG_POST )
 349                         {
 350                                 foreach_header(i, req->headers)
 351                                 {
 352                                         if( ! strcasecmp(req->headers[i], "Content-Length") )
 353                                         {
 354                                                 content_length = atoi(req->headers[i+1]);
 355                                                 break;
 356                                         }
 357                                 }
 358                         }
 359
 360
 361                         memset(hdr, 0, sizeof(hdr));
 362
 363                         timeout.tv_sec = cl->server->conf->script_timeout;
 364                         timeout.tv_usec = 0;
 365
 366 #define ensure(x) \
 367         do { if( x < 0 ) goto out; } while(0)
 368
 369                         /* I/O loop, watch our pipe ends and dispatch child reads/writes from/to socket */
 370                         while( 1 )
 371                         {
 372                                 FD_ZERO(&reader);
 373                                 FD_ZERO(&writer);
 374
 375                                 FD_SET(rfd[0], &reader);
 376                                 FD_SET(wfd[1], &writer);
 377
 378                                 /* wait until we can read or write or both */
 379                                 if( select_intr(fd_max, &reader,
 380                                         (content_length > -1) ? &writer : NULL, NULL,
 381                                         (header_sent < 1) ? &timeout : NULL) > 0
 382                                 ) {
 383                                         /* ready to write to cgi program */
 384                                         if( FD_ISSET(wfd[1], &writer) )
 385                                         {
 386                                                 /* there is unread post data waiting */
 387                                                 if( content_length > 0 )
 388                                                 {
 389                                                         /* read it from socket ... */
 390                                                         if( (buflen = uh_tcp_recv(cl, buf, min(content_length, sizeof(buf)))) > 0 )
 391                                                         {
 392                                                                 /* ... and write it to child's stdin */
 393                                                                 if( write(wfd[1], buf, buflen) < 0 )
 394                                                                         perror("write()");
 395
 396                                                                 content_length -= buflen;
 397                                                         }
 398
 399                                                         /* unexpected eof! */
 400                                                         else
 401                                                         {
 402                                                                 if( write(wfd[1], "", 0) < 0 )
 403                                                                         perror("write()");
 404
 405                                                                 content_length = 0;
 406                                                         }
 407                                                 }
 408
 409                                                 /* there is no more post data, close pipe to child's stdin */
 410                                                 else if( content_length > -1 )
 411                                                 {
 412                                                         close(wfd[1]);
 413                                                         content_length = -1;
 414                                                 }
 415                                         }
 416
 417                                         /* ready to read from cgi program */
 418                                         if( FD_ISSET(rfd[0], &reader) )
 419                                         {
 420                                                 /* read data from child ... */
 421                                                 if( (buflen = read(rfd[0], buf, sizeof(buf))) > 0 )
 422                                                 {
 423                                                         /* we have not pushed out headers yet, parse input */
 424                                                         if( ! header_sent )
 425                                                         {
 426                                                                 /* head buffer not full and no end yet */
 427                                                                 if( hdrlen < sizeof(hdr) )
 428                                                                 {
 429                                                                         bufoff = min(buflen, sizeof(hdr) - hdrlen);
 430                                                                         memcpy(&hdr[hdrlen], buf, bufoff);
 431                                                                         hdrlen += bufoff;
 432                                                                 }
 433                                                                 else
 434                                                                 {
 435                                                                         bufoff = 0;
 436                                                                 }
 437
 438
 439                                                                 /* try to parse header ... */
 440                                                                 if( (res = uh_cgi_header_parse(hdr, hdrlen, &hdroff)) != NULL )
 441                                                                 {
 442                                                                         /* write status */
 443                                                                         ensure(uh_http_sendf(cl, NULL,
 444                                                                                 "HTTP/%.1f %03d %s\r\n"
 445                                                                                 "Connection: close\r\n",
 446                                                                                 req->version, res->statuscode,
 447                                                                                 res->statusmsg));
 448
 449                                                                         /* add Content-Type if no Location or Content-Type */
 450                                                                         if( !uh_cgi_header_lookup(res, "Location") &&
 451                                                                             !uh_cgi_header_lookup(res, "Content-Type")
 452                                                                         ) {
 453                                                                                 ensure(uh_http_send(cl, NULL,
 454                                                                                         "Content-Type: text/plain\r\n", -1));
 455                                                                         }
 456
 457                                                                         /* if request was HTTP 1.1 we'll respond chunked */
 458                                                                         if( (req->version > 1.0) &&
 459                                                                             !uh_cgi_header_lookup(res, "Transfer-Encoding")
 460                                                                         ) {
 461                                                                                 ensure(uh_http_send(cl, NULL,
 462                                                                                         "Transfer-Encoding: chunked\r\n", -1));
 463                                                                         }
 464
 465                                                                         /* write headers from CGI program */
 466                                                                         foreach_header(i, res->headers)
 467                                                                         {
 468                                                                                 ensure(uh_http_sendf(cl, NULL, "%s: %s\r\n",
 469                                                                                         res->headers[i], res->headers[i+1]));
 470                                                                         }
 471
 472                                                                         /* terminate header */
 473                                                                         ensure(uh_http_send(cl, NULL, "\r\n", -1));
 474
 475                                                                         /* push out remaining head buffer */
 476                                                                         if( hdroff < hdrlen )
 477                                                                                 ensure(uh_http_send(cl, req, &hdr[hdroff], hdrlen - hdroff));
 478                                                                 }
 479
 480                                                                 /* ... failed and head buffer exceeded */
 481                                                                 else if( hdrlen >= sizeof(hdr) )
 482                                                                 {
 483                                                                         ensure(uh_cgi_error_500(cl, req,
 484                                                                                 "The CGI program generated an invalid response:\n\n"));
 485
 486                                                                         ensure(uh_http_send(cl, req, hdr, hdrlen));
 487                                                                 }
 488
 489                                                                 /* ... failed but free buffer space, try again */
 490                                                                 else
 491                                                                 {
 492                                                                         continue;
 493                                                                 }
 494
 495                                                                 /* push out remaining read buffer */
 496                                                                 if( bufoff < buflen )
 497                                                                         ensure(uh_http_send(cl, req, &buf[bufoff], buflen - bufoff));
 498
 499                                                                 header_sent = 1;
 500                                                                 continue;
 501                                                         }
 502
 503
 504                                                         /* headers complete, pass through buffer to socket */
 505                                                         ensure(uh_http_send(cl, req, buf, buflen));
 506                                                 }
 507
 508                                                 /* looks like eof from child */
 509                                                 else
 510                                                 {
 511                                                         /* cgi script did not output useful stuff at all */
 512                                                         if( ! header_sent )
 513                                                         {
 514                                                                 /* I would do this ...
 515                                                                  *
 516                                                                  *    uh_cgi_error_500(cl, req,
 517                                                                  *        "The CGI program generated an "
 518                                                                  *        "invalid response:\n\n");
 519                                                                  *
 520                                                                  * ... but in order to stay as compatible as possible,
 521                                                                  * treat whatever we got as text/plain response and
 522                                                                  * build the required headers here.
 523                                                                  */
 524
 525                                                                 ensure(uh_http_sendf(cl, NULL,
 526                                                                         "HTTP/%.1f 200 OK\r\n"
 527                                                                         "Content-Type: text/plain\r\n"
 528                                                                         "%s\r\n",
 529                                                                                 req->version, (req->version > 1.0)
 530                                                                                         ? "Transfer-Encoding: chunked\r\n" : ""
 531                                                                 ));
 532
 533                                                                 ensure(uh_http_send(cl, req, hdr, hdrlen));
 534                                                         }
 535
 536                                                         /* send final chunk if we're in chunked transfer mode */
 537                                                         ensure(uh_http_send(cl, req, "", 0));
 538                                                         break;
 539                                                 }
 540                                         }
 541                                 }
 542
 543                                 /* timeout exceeded or interrupted by SIGCHLD */
 544                                 else
 545                                 {
 546                                         if( (errno != EINTR) && ! header_sent )
 547                                         {
 548                                                 ensure(uh_http_sendhf(cl, 504, "Gateway Timeout",
 549                                                         "The CGI script took too long to produce "
 550                                                         "a response"));
 551                                         }
 552
 553                                         /* send final chunk if we're in chunked transfer mode */
 554                                         ensure(uh_http_send(cl, req, "", 0));
 555
 556                                         break;
 557                                 }
 558                         }
 559
 560                 out:
 561                         close(rfd[0]);
 562                         close(wfd[1]);
 563
 564                         if( !kill(child, 0) )
 565                         {
 566                                 kill(child, SIGTERM);
 567                                 waitpid(child, NULL, 0);
 568                         }
 569
 570                         break;
 571         }
 572 }
 573