package/uhttpd/src/uhttpd-cgi.c

   1 /*
   2  * uhttpd - Tiny single-threaded httpd - CGI handler
   3  *
   4  *   Copyright (C) 2010-2011 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 < *off; 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                                 if( ! hdrname )
  64                                         break;
  65
  66                                 buf[pos++] = 0;
  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(
 139         struct client *cl, struct http_request *req,
 140         struct path_info *pi, struct interpreter *ip
 141 ) {
 142         int i, hdroff, bufoff, rv;
 143         int hdrlen = 0;
 144         int buflen = 0;
 145         int fd_max = 0;
 146         int content_length = 0;
 147         int header_sent = 0;
 148
 149         int rfd[2] = { 0, 0 };
 150         int wfd[2] = { 0, 0 };
 151
 152         char buf[UH_LIMIT_MSGHEAD];
 153         char hdr[UH_LIMIT_MSGHEAD];
 154
 155         pid_t child;
 156
 157         fd_set reader;
 158         fd_set writer;
 159
 160         sigset_t ss;
 161
 162         struct sigaction sa;
 163         struct timeval timeout;
 164         struct http_response *res;
 165
 166
 167         /* spawn pipes for me->child, child->me */
 168         if( (pipe(rfd) < 0) || (pipe(wfd) < 0) )
 169         {
 170                 uh_http_sendhf(cl, 500, "Internal Server Error",
 171                         "Failed to create pipe: %s", strerror(errno));
 172
 173                 if( rfd[0] > 0 ) close(rfd[0]);
 174                 if( rfd[1] > 0 ) close(rfd[1]);
 175                 if( wfd[0] > 0 ) close(wfd[0]);
 176                 if( wfd[1] > 0 ) close(wfd[1]);
 177
 178                 return;
 179         }
 180
 181         /* fork off child process */
 182         switch( (child = fork()) )
 183         {
 184                 /* oops */
 185                 case -1:
 186                         uh_http_sendhf(cl, 500, "Internal Server Error",
 187                                 "Failed to fork child: %s", strerror(errno));
 188                         return;
 189
 190                 /* exec child */
 191                 case 0:
 192                         /* unblock signals */
 193                         sigemptyset(&ss);
 194                         sigprocmask(SIG_SETMASK, &ss, NULL);
 195
 196                         /* restore SIGTERM */
 197                         sa.sa_flags = 0;
 198                         sa.sa_handler = SIG_DFL;
 199                         sigemptyset(&sa.sa_mask);
 200                         sigaction(SIGTERM, &sa, NULL);
 201
 202                         /* close loose pipe ends */
 203                         close(rfd[0]);
 204                         close(wfd[1]);
 205
 206                         /* patch stdout and stdin to pipes */
 207                         dup2(rfd[1], 1);
 208                         dup2(wfd[0], 0);
 209
 210                         /* avoid leaking our pipe into child-child processes */
 211                         fd_cloexec(rfd[1]);
 212                         fd_cloexec(wfd[0]);
 213
 214                         /* check for regular, world-executable file _or_ interpreter */
 215                         if( ((pi->stat.st_mode & S_IFREG) &&
 216                              (pi->stat.st_mode & S_IXOTH)) || (ip != NULL)
 217                         ) {
 218                                 /* build environment */
 219                                 clearenv();
 220
 221                                 /* common information */
 222                                 setenv("GATEWAY_INTERFACE", "CGI/1.1", 1);
 223                                 setenv("SERVER_SOFTWARE", "uHTTPd", 1);
 224                                 setenv("PATH", "/sbin:/usr/sbin:/bin:/usr/bin", 1);
 225
 226 #ifdef HAVE_TLS
 227                                 /* https? */
 228                                 if( cl->tls )
 229                                         setenv("HTTPS", "on", 1);
 230 #endif
 231
 232                                 /* addresses */
 233                                 setenv("SERVER_NAME", sa_straddr(&cl->servaddr), 1);
 234                                 setenv("SERVER_ADDR", sa_straddr(&cl->servaddr), 1);
 235                                 setenv("SERVER_PORT", sa_strport(&cl->servaddr), 1);
 236                                 setenv("REMOTE_HOST", sa_straddr(&cl->peeraddr), 1);
 237                                 setenv("REMOTE_ADDR", sa_straddr(&cl->peeraddr), 1);
 238                                 setenv("REMOTE_PORT", sa_strport(&cl->peeraddr), 1);
 239
 240                                 /* path information */
 241                                 setenv("SCRIPT_NAME", pi->name, 1);
 242                                 setenv("SCRIPT_FILENAME", pi->phys, 1);
 243                                 setenv("DOCUMENT_ROOT", pi->root, 1);
 244                                 setenv("QUERY_STRING", pi->query ? pi->query : "", 1);
 245
 246                                 if( pi->info )
 247                                         setenv("PATH_INFO", pi->info, 1);
 248
 249                                 /* REDIRECT_STATUS, php-cgi wants it */
 250                                 switch( req->redirect_status )
 251                                 {
 252                                         case 404:
 253                                                 setenv("REDIRECT_STATUS", "404", 1);
 254                                                 break;
 255
 256                                         default:
 257                                                 setenv("REDIRECT_STATUS", "200", 1);
 258                                                 break;
 259                                 }
 260
 261                                 /* http version */
 262                                 if( req->version > 1.0 )
 263                                         setenv("SERVER_PROTOCOL", "HTTP/1.1", 1);
 264                                 else
 265                                         setenv("SERVER_PROTOCOL", "HTTP/1.0", 1);
 266
 267                                 /* request method */
 268                                 switch( req->method )
 269                                 {
 270                                         case UH_HTTP_MSG_GET:
 271                                                 setenv("REQUEST_METHOD", "GET", 1);
 272                                                 break;
 273
 274                                         case UH_HTTP_MSG_HEAD:
 275                                                 setenv("REQUEST_METHOD", "HEAD", 1);
 276                                                 break;
 277
 278                                         case UH_HTTP_MSG_POST:
 279                                                 setenv("REQUEST_METHOD", "POST", 1);
 280                                                 break;
 281                                 }
 282
 283                                 /* request url */
 284                                 setenv("REQUEST_URI", req->url, 1);
 285
 286                                 /* remote user */
 287                                 if( req->realm )
 288                                         setenv("REMOTE_USER", req->realm->user, 1);
 289
 290                                 /* request message headers */
 291                                 foreach_header(i, req->headers)
 292                                 {
 293                                         if( ! strcasecmp(req->headers[i], "Accept") )
 294                                                 setenv("HTTP_ACCEPT", req->headers[i+1], 1);
 295
 296                                         else if( ! strcasecmp(req->headers[i], "Accept-Charset") )
 297                                                 setenv("HTTP_ACCEPT_CHARSET", req->headers[i+1], 1);
 298
 299                                         else if( ! strcasecmp(req->headers[i], "Accept-Encoding") )
 300                                                 setenv("HTTP_ACCEPT_ENCODING", req->headers[i+1], 1);
 301
 302                                         else if( ! strcasecmp(req->headers[i], "Accept-Language") )
 303                                                 setenv("HTTP_ACCEPT_LANGUAGE", req->headers[i+1], 1);
 304
 305                                         else if( ! strcasecmp(req->headers[i], "Authorization") )
 306                                                 setenv("HTTP_AUTHORIZATION", req->headers[i+1], 1);
 307
 308                                         else if( ! strcasecmp(req->headers[i], "Connection") )
 309                                                 setenv("HTTP_CONNECTION", req->headers[i+1], 1);
 310
 311                                         else if( ! strcasecmp(req->headers[i], "Cookie") )
 312                                                 setenv("HTTP_COOKIE", req->headers[i+1], 1);
 313
 314                                         else if( ! strcasecmp(req->headers[i], "Host") )
 315                                                 setenv("HTTP_HOST", req->headers[i+1], 1);
 316
 317                                         else if( ! strcasecmp(req->headers[i], "Referer") )
 318                                                 setenv("HTTP_REFERER", req->headers[i+1], 1);
 319
 320                                         else if( ! strcasecmp(req->headers[i], "User-Agent") )
 321                                                 setenv("HTTP_USER_AGENT", req->headers[i+1], 1);
 322
 323                                         else if( ! strcasecmp(req->headers[i], "Content-Type") )
 324                                                 setenv("CONTENT_TYPE", req->headers[i+1], 1);
 325
 326                                         else if( ! strcasecmp(req->headers[i], "Content-Length") )
 327                                                 setenv("CONTENT_LENGTH", req->headers[i+1], 1);
 328                                 }
 329
 330
 331                                 /* execute child code ... */
 332                                 if( chdir(pi->root) )
 333                                         perror("chdir()");
 334
 335                                 if( ip != NULL )
 336                                         execl(ip->path, ip->path, pi->phys, NULL);
 337                                 else
 338                                         execl(pi->phys, pi->phys, NULL);
 339
 340                                 /* in case it fails ... */
 341                                 printf(
 342                                         "Status: 500 Internal Server Error\r\n\r\n"
 343                                         "Unable to launch the requested CGI program:\n"
 344                                         "  %s: %s\n",
 345                                                 ip ? ip->path : pi->phys, strerror(errno)
 346                                 );
 347                         }
 348
 349                         /* 403 */
 350                         else
 351                         {
 352                                 printf(
 353                                         "Status: 403 Forbidden\r\n\r\n"
 354                                         "Access to this resource is forbidden\n"
 355                                 );
 356                         }
 357
 358                         close(wfd[0]);
 359                         close(rfd[1]);
 360                         exit(0);
 361
 362                         break;
 363
 364                 /* parent; handle I/O relaying */
 365                 default:
 366                         /* close unneeded pipe ends */
 367                         close(rfd[1]);
 368                         close(wfd[0]);
 369
 370                         /* max watch fd */
 371                         fd_max = max(rfd[0], wfd[1]) + 1;
 372
 373                         /* find content length */
 374                         if( req->method == UH_HTTP_MSG_POST )
 375                         {
 376                                 foreach_header(i, req->headers)
 377                                 {
 378                                         if( ! strcasecmp(req->headers[i], "Content-Length") )
 379                                         {
 380                                                 content_length = atoi(req->headers[i+1]);
 381                                                 break;
 382                                         }
 383                                 }
 384                         }
 385
 386
 387                         memset(hdr, 0, sizeof(hdr));
 388
 389                         /* I/O loop, watch our pipe ends and dispatch child reads/writes from/to socket */
 390                         while( 1 )
 391                         {
 392                                 FD_ZERO(&reader);
 393                                 FD_ZERO(&writer);
 394
 395                                 FD_SET(rfd[0], &reader);
 396                                 FD_SET(wfd[1], &writer);
 397
 398                                 timeout.tv_sec = (header_sent < 1) ? cl->server->conf->script_timeout : 3;
 399                                 timeout.tv_usec = 0;
 400
 401                                 ensure_out(rv = select_intr(fd_max, &reader,
 402                                         (content_length > -1) ? &writer : NULL, NULL, &timeout));
 403
 404                                 /* timeout */
 405                                 if( rv == 0 )
 406                                 {
 407                                         ensure_out(kill(child, 0));
 408                                 }
 409
 410                                 /* wait until we can read or write or both */
 411                                 else if( rv > 0 )
 412                                 {
 413                                         /* ready to write to cgi program */
 414                                         if( FD_ISSET(wfd[1], &writer) )
 415                                         {
 416                                                 /* there is unread post data waiting */
 417                                                 if( content_length > 0 )
 418                                                 {
 419                                                         /* read it from socket ... */
 420                                                         ensure_out(buflen = uh_tcp_recv(cl, buf,
 421                                                                 min(content_length, sizeof(buf))));
 422
 423                                                         if( buflen > 0 )
 424                                                         {
 425                                                                 /* ... and write it to child's stdin */
 426                                                                 if( write(wfd[1], buf, buflen) < 0 )
 427                                                                         perror("write()");
 428
 429                                                                 content_length -= buflen;
 430                                                         }
 431
 432                                                         /* unexpected eof! */
 433                                                         else
 434                                                         {
 435                                                                 if( write(wfd[1], "", 0) < 0 )
 436                                                                         perror("write()");
 437
 438                                                                 content_length = 0;
 439                                                         }
 440                                                 }
 441
 442                                                 /* there is no more post data, close pipe to child's stdin */
 443                                                 else if( content_length > -1 )
 444                                                 {
 445                                                         close(wfd[1]);
 446                                                         content_length = -1;
 447                                                 }
 448                                         }
 449
 450                                         /* ready to read from cgi program */
 451                                         if( FD_ISSET(rfd[0], &reader) )
 452                                         {
 453                                                 /* read data from child ... */
 454                                                 if( (buflen = read(rfd[0], buf, sizeof(buf))) > 0 )
 455                                                 {
 456                                                         /* we have not pushed out headers yet, parse input */
 457                                                         if( ! header_sent )
 458                                                         {
 459                                                                 /* head buffer not full and no end yet */
 460                                                                 if( hdrlen < sizeof(hdr) )
 461                                                                 {
 462                                                                         bufoff = min(buflen, sizeof(hdr) - hdrlen);
 463                                                                         memcpy(&hdr[hdrlen], buf, bufoff);
 464                                                                         hdrlen += bufoff;
 465                                                                 }
 466                                                                 else
 467                                                                 {
 468                                                                         bufoff = 0;
 469                                                                 }
 470
 471
 472                                                                 /* try to parse header ... */
 473                                                                 if( (res = uh_cgi_header_parse(hdr, hdrlen, &hdroff)) != NULL )
 474                                                                 {
 475                                                                         /* write status */
 476                                                                         ensure_out(uh_http_sendf(cl, NULL,
 477                                                                                 "HTTP/%.1f %03d %s\r\n"
 478                                                                                 "Connection: close\r\n",
 479                                                                                 req->version, res->statuscode,
 480                                                                                 res->statusmsg));
 481
 482                                                                         /* add Content-Type if no Location or Content-Type */
 483                                                                         if( !uh_cgi_header_lookup(res, "Location") &&
 484                                                                             !uh_cgi_header_lookup(res, "Content-Type")
 485                                                                         ) {
 486                                                                                 ensure_out(uh_http_send(cl, NULL,
 487                                                                                         "Content-Type: text/plain\r\n", -1));
 488                                                                         }
 489
 490                                                                         /* if request was HTTP 1.1 we'll respond chunked */
 491                                                                         if( (req->version > 1.0) &&
 492                                                                             !uh_cgi_header_lookup(res, "Transfer-Encoding")
 493                                                                         ) {
 494                                                                                 ensure_out(uh_http_send(cl, NULL,
 495                                                                                         "Transfer-Encoding: chunked\r\n", -1));
 496                                                                         }
 497
 498                                                                         /* write headers from CGI program */
 499                                                                         foreach_header(i, res->headers)
 500                                                                         {
 501                                                                                 ensure_out(uh_http_sendf(cl, NULL, "%s: %s\r\n",
 502                                                                                         res->headers[i], res->headers[i+1]));
 503                                                                         }
 504
 505                                                                         /* terminate header */
 506                                                                         ensure_out(uh_http_send(cl, NULL, "\r\n", -1));
 507
 508                                                                         /* push out remaining head buffer */
 509                                                                         if( hdroff < hdrlen )
 510                                                                                 ensure_out(uh_http_send(cl, req, &hdr[hdroff], hdrlen - hdroff));
 511                                                                 }
 512
 513                                                                 /* ... failed and head buffer exceeded */
 514                                                                 else if( hdrlen >= sizeof(hdr) )
 515                                                                 {
 516                                                                         ensure_out(uh_cgi_error_500(cl, req,
 517                                                                                 "The CGI program generated an invalid response:\n\n"));
 518
 519                                                                         ensure_out(uh_http_send(cl, req, hdr, hdrlen));
 520                                                                 }
 521
 522                                                                 /* ... failed but free buffer space, try again */
 523                                                                 else
 524                                                                 {
 525                                                                         continue;
 526                                                                 }
 527
 528                                                                 /* push out remaining read buffer */
 529                                                                 if( bufoff < buflen )
 530                                                                         ensure_out(uh_http_send(cl, req, &buf[bufoff], buflen - bufoff));
 531
 532                                                                 header_sent = 1;
 533                                                                 continue;
 534                                                         }
 535
 536
 537                                                         /* headers complete, pass through buffer to socket */
 538                                                         ensure_out(uh_http_send(cl, req, buf, buflen));
 539                                                 }
 540
 541                                                 /* looks like eof from child */
 542                                                 else
 543                                                 {
 544                                                         /* cgi script did not output useful stuff at all */
 545                                                         if( ! header_sent )
 546                                                         {
 547                                                                 /* I would do this ...
 548                                                                  *
 549                                                                  *    uh_cgi_error_500(cl, req,
 550                                                                  *        "The CGI program generated an "
 551                                                                  *        "invalid response:\n\n");
 552                                                                  *
 553                                                                  * ... but in order to stay as compatible as possible,
 554                                                                  * treat whatever we got as text/plain response and
 555                                                                  * build the required headers here.
 556                                                                  */
 557
 558                                                                 ensure_out(uh_http_sendf(cl, NULL,
 559                                                                         "HTTP/%.1f 200 OK\r\n"
 560                                                                         "Content-Type: text/plain\r\n"
 561                                                                         "%s\r\n",
 562                                                                                 req->version, (req->version > 1.0)
 563                                                                                         ? "Transfer-Encoding: chunked\r\n" : ""
 564                                                                 ));
 565
 566                                                                 ensure_out(uh_http_send(cl, req, hdr, hdrlen));
 567                                                         }
 568
 569                                                         /* send final chunk if we're in chunked transfer mode */
 570                                                         ensure_out(uh_http_send(cl, req, "", 0));
 571                                                         break;
 572                                                 }
 573                                         }
 574                                 }
 575
 576                                 /* timeout exceeded or interrupted by SIGCHLD */
 577                                 else
 578                                 {
 579                                         if( (errno != EINTR) && ! header_sent )
 580                                         {
 581                                                 ensure_out(uh_http_sendhf(cl, 504, "Gateway Timeout",
 582                                                         "The CGI script took too long to produce "
 583                                                         "a response"));
 584                                         }
 585
 586                                         /* send final chunk if we're in chunked transfer mode */
 587                                         ensure_out(uh_http_send(cl, req, "", 0));
 588
 589                                         break;
 590                                 }
 591                         }
 592
 593                 out:
 594                         close(rfd[0]);
 595                         close(wfd[1]);
 596
 597                         if( !kill(child, 0) )
 598                         {
 599                                 kill(child, SIGTERM);
 600                                 waitpid(child, NULL, 0);
 601                         }
 602
 603                         break;
 604         }
 605 }
 606