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) &&
  83                                                                 (&bufptr[1] != 0))
  84                                                         {
  85                                                                 res.statusmsg = &bufptr[1];
  86                                                         }
  87                                                 }
  88                                                 else
  89                                                 {
  90                                                         res.headers[hdrcount++] = hdrname;
  91                                                         res.headers[hdrcount++] = bufptr;
  92                                                 }
  93
  94                                                 bufptr = &buf[pos];
  95                                                 hdrname = NULL;
  96                                         }
  97                                         else
  98                                         {
  99                                                 return NULL;
 100                                         }
 101                                 }
 102                         }
 103                 }
 104
 105                 return &res;
 106         }
 107
 108         return NULL;
 109 }
 110
 111 static char * uh_cgi_header_lookup(struct http_response *res,
 112                                                                    const char *hdrname)
 113 {
 114         int i;
 115
 116         foreach_header(i, res->headers)
 117         {
 118                 if (!strcasecmp(res->headers[i], hdrname))
 119                         return res->headers[i+1];
 120         }
 121
 122         return NULL;
 123 }
 124
 125 static int uh_cgi_error_500(struct client *cl, struct http_request *req,
 126                                                         const char *message)
 127 {
 128         if (uh_http_sendf(cl, NULL,
 129                                           "HTTP/%.1f 500 Internal Server Error\r\n"
 130                                           "Content-Type: text/plain\r\n%s\r\n",
 131                                           req->version,
 132                                           (req->version > 1.0)
 133                                               ? "Transfer-Encoding: chunked\r\n" : "") >= 0)
 134         {
 135                 return uh_http_send(cl, req, message, -1);
 136         }
 137
 138         return -1;
 139 }
 140
 141
 142 void uh_cgi_request(struct client *cl, struct http_request *req,
 143                                         struct path_info *pi, struct interpreter *ip)
 144 {
 145         int i, hdroff, bufoff, rv;
 146         int hdrlen = 0;
 147         int buflen = 0;
 148         int fd_max = 0;
 149         int content_length = 0;
 150         int header_sent = 0;
 151
 152         int rfd[2] = { 0, 0 };
 153         int wfd[2] = { 0, 0 };
 154
 155         char buf[UH_LIMIT_MSGHEAD];
 156         char hdr[UH_LIMIT_MSGHEAD];
 157
 158         pid_t child;
 159
 160         fd_set reader;
 161         fd_set writer;
 162
 163         sigset_t ss;
 164
 165         struct sigaction sa;
 166         struct timeval timeout;
 167         struct http_response *res;
 168
 169
 170         /* spawn pipes for me->child, child->me */
 171         if ((pipe(rfd) < 0) || (pipe(wfd) < 0))
 172         {
 173                 uh_http_sendhf(cl, 500, "Internal Server Error",
 174                                            "Failed to create pipe: %s", strerror(errno));
 175
 176                 if (rfd[0] > 0) close(rfd[0]);
 177                 if (rfd[1] > 0) close(rfd[1]);
 178                 if (wfd[0] > 0) close(wfd[0]);
 179                 if (wfd[1] > 0) close(wfd[1]);
 180
 181                 return;
 182         }
 183
 184         /* fork off child process */
 185         switch ((child = fork()))
 186         {
 187                 /* oops */
 188                 case -1:
 189                         uh_http_sendhf(cl, 500, "Internal Server Error",
 190                                                    "Failed to fork child: %s", strerror(errno));
 191                         return;
 192
 193                 /* exec child */
 194                 case 0:
 195                         /* unblock signals */
 196                         sigemptyset(&ss);
 197                         sigprocmask(SIG_SETMASK, &ss, NULL);
 198
 199                         /* restore SIGTERM */
 200                         sa.sa_flags = 0;
 201                         sa.sa_handler = SIG_DFL;
 202                         sigemptyset(&sa.sa_mask);
 203                         sigaction(SIGTERM, &sa, NULL);
 204
 205                         /* close loose pipe ends */
 206                         close(rfd[0]);
 207                         close(wfd[1]);
 208
 209                         /* patch stdout and stdin to pipes */
 210                         dup2(rfd[1], 1);
 211                         dup2(wfd[0], 0);
 212
 213                         /* avoid leaking our pipe into child-child processes */
 214                         fd_cloexec(rfd[1]);
 215                         fd_cloexec(wfd[0]);
 216
 217                         /* check for regular, world-executable file _or_ interpreter */
 218                         if (((pi->stat.st_mode & S_IFREG) &&
 219                              (pi->stat.st_mode & S_IXOTH)) || (ip != NULL))
 220                         {
 221                                 /* build environment */
 222                                 clearenv();
 223
 224                                 /* common information */
 225                                 setenv("GATEWAY_INTERFACE", "CGI/1.1", 1);
 226                                 setenv("SERVER_SOFTWARE", "uHTTPd", 1);
 227                                 setenv("PATH", "/sbin:/usr/sbin:/bin:/usr/bin", 1);
 228
 229 #ifdef HAVE_TLS
 230                                 /* https? */
 231                                 if (cl->tls)
 232                                         setenv("HTTPS", "on", 1);
 233 #endif
 234
 235                                 /* addresses */
 236                                 setenv("SERVER_NAME", sa_straddr(&cl->servaddr), 1);
 237                                 setenv("SERVER_ADDR", sa_straddr(&cl->servaddr), 1);
 238                                 setenv("SERVER_PORT", sa_strport(&cl->servaddr), 1);
 239                                 setenv("REMOTE_HOST", sa_straddr(&cl->peeraddr), 1);
 240                                 setenv("REMOTE_ADDR", sa_straddr(&cl->peeraddr), 1);
 241                                 setenv("REMOTE_PORT", sa_strport(&cl->peeraddr), 1);
 242
 243                                 /* path information */
 244                                 setenv("SCRIPT_NAME", pi->name, 1);
 245                                 setenv("SCRIPT_FILENAME", pi->phys, 1);
 246                                 setenv("DOCUMENT_ROOT", pi->root, 1);
 247                                 setenv("QUERY_STRING", pi->query ? pi->query : "", 1);
 248
 249                                 if (pi->info)
 250                                         setenv("PATH_INFO", pi->info, 1);
 251
 252                                 /* REDIRECT_STATUS, php-cgi wants it */
 253                                 switch (req->redirect_status)
 254                                 {
 255                                         case 404:
 256                                                 setenv("REDIRECT_STATUS", "404", 1);
 257                                                 break;
 258
 259                                         default:
 260                                                 setenv("REDIRECT_STATUS", "200", 1);
 261                                                 break;
 262                                 }
 263
 264                                 /* http version */
 265                                 if (req->version > 1.0)
 266                                         setenv("SERVER_PROTOCOL", "HTTP/1.1", 1);
 267                                 else
 268                                         setenv("SERVER_PROTOCOL", "HTTP/1.0", 1);
 269
 270                                 /* request method */
 271                                 switch (req->method)
 272                                 {
 273                                         case UH_HTTP_MSG_GET:
 274                                                 setenv("REQUEST_METHOD", "GET", 1);
 275                                                 break;
 276
 277                                         case UH_HTTP_MSG_HEAD:
 278                                                 setenv("REQUEST_METHOD", "HEAD", 1);
 279                                                 break;
 280
 281                                         case UH_HTTP_MSG_POST:
 282                                                 setenv("REQUEST_METHOD", "POST", 1);
 283                                                 break;
 284                                 }
 285
 286                                 /* request url */
 287                                 setenv("REQUEST_URI", req->url, 1);
 288
 289                                 /* remote user */
 290                                 if (req->realm)
 291                                         setenv("REMOTE_USER", req->realm->user, 1);
 292
 293                                 /* request message headers */
 294                                 foreach_header(i, req->headers)
 295                                 {
 296                                         if (!strcasecmp(req->headers[i], "Accept"))
 297                                                 setenv("HTTP_ACCEPT", req->headers[i+1], 1);
 298
 299                                         else if (!strcasecmp(req->headers[i], "Accept-Charset"))
 300                                                 setenv("HTTP_ACCEPT_CHARSET", req->headers[i+1], 1);
 301
 302                                         else if (!strcasecmp(req->headers[i], "Accept-Encoding"))
 303                                                 setenv("HTTP_ACCEPT_ENCODING", req->headers[i+1], 1);
 304
 305                                         else if (!strcasecmp(req->headers[i], "Accept-Language"))
 306                                                 setenv("HTTP_ACCEPT_LANGUAGE", req->headers[i+1], 1);
 307
 308                                         else if (!strcasecmp(req->headers[i], "Authorization"))
 309                                                 setenv("HTTP_AUTHORIZATION", req->headers[i+1], 1);
 310
 311                                         else if (!strcasecmp(req->headers[i], "Connection"))
 312                                                 setenv("HTTP_CONNECTION", req->headers[i+1], 1);
 313
 314                                         else if (!strcasecmp(req->headers[i], "Cookie"))
 315                                                 setenv("HTTP_COOKIE", req->headers[i+1], 1);
 316
 317                                         else if (!strcasecmp(req->headers[i], "Host"))
 318                                                 setenv("HTTP_HOST", req->headers[i+1], 1);
 319
 320                                         else if (!strcasecmp(req->headers[i], "Referer"))
 321                                                 setenv("HTTP_REFERER", req->headers[i+1], 1);
 322
 323                                         else if (!strcasecmp(req->headers[i], "User-Agent"))
 324                                                 setenv("HTTP_USER_AGENT", req->headers[i+1], 1);
 325
 326                                         else if (!strcasecmp(req->headers[i], "Content-Type"))
 327                                                 setenv("CONTENT_TYPE", req->headers[i+1], 1);
 328
 329                                         else if (!strcasecmp(req->headers[i], "Content-Length"))
 330                                                 setenv("CONTENT_LENGTH", req->headers[i+1], 1);
 331                                 }
 332
 333
 334                                 /* execute child code ... */
 335                                 if (chdir(pi->root))
 336                                         perror("chdir()");
 337
 338                                 if (ip != NULL)
 339                                         execl(ip->path, ip->path, pi->phys, NULL);
 340                                 else
 341                                         execl(pi->phys, pi->phys, NULL);
 342
 343                                 /* in case it fails ... */
 344                                 printf("Status: 500 Internal Server Error\r\n\r\n"
 345                                            "Unable to launch the requested CGI program:\n"
 346                                            "  %s: %s\n",
 347                                            ip ? ip->path : pi->phys, strerror(errno));
 348                         }
 349
 350                         /* 403 */
 351                         else
 352                         {
 353                                 printf("Status: 403 Forbidden\r\n\r\n"
 354                                            "Access to this resource is forbidden\n");
 355                         }
 356
 357                         close(wfd[0]);
 358                         close(rfd[1]);
 359                         exit(0);
 360
 361                         break;
 362
 363                 /* parent; handle I/O relaying */
 364                 default:
 365                         /* close unneeded pipe ends */
 366                         close(rfd[1]);
 367                         close(wfd[0]);
 368
 369                         /* max watch fd */
 370                         fd_max = max(rfd[0], wfd[1]) + 1;
 371
 372                         /* find content length */
 373                         if (req->method == UH_HTTP_MSG_POST)
 374                         {
 375                                 foreach_header(i, req->headers)
 376                                 {
 377                                         if (!strcasecmp(req->headers[i], "Content-Length"))
 378                                         {
 379                                                 content_length = atoi(req->headers[i+1]);
 380                                                 break;
 381                                         }
 382                                 }
 383                         }
 384
 385
 386                         memset(hdr, 0, sizeof(hdr));
 387
 388                         /* I/O loop, watch our pipe ends and dispatch child reads/writes from/to socket */
 389                         while (1)
 390                         {
 391                                 FD_ZERO(&reader);
 392                                 FD_ZERO(&writer);
 393
 394                                 FD_SET(rfd[0], &reader);
 395                                 FD_SET(wfd[1], &writer);
 396
 397                                 timeout.tv_sec = (header_sent < 1) ? cl->server->conf->script_timeout : 3;
 398                                 timeout.tv_usec = 0;
 399
 400                                 ensure_out(rv = select_intr(fd_max, &reader,
 401                                                                                         (content_length > -1)
 402                                                                                                 ? &writer : NULL,
 403                                                                                         NULL, &timeout));
 404
 405                                 /* timeout */
 406                                 if (rv == 0)
 407                                 {
 408                                         ensure_out(kill(child, 0));
 409                                 }
 410
 411                                 /* wait until we can read or write or both */
 412                                 else if (rv > 0)
 413                                 {
 414                                         /* ready to write to cgi program */
 415                                         if (FD_ISSET(wfd[1], &writer))
 416                                         {
 417                                                 /* there is unread post data waiting */
 418                                                 if (content_length > 0)
 419                                                 {
 420                                                         /* read it from socket ... */
 421                                                         ensure_out(buflen = uh_tcp_recv(cl, buf,
 422                                                                 min(content_length, sizeof(buf))));
 423
 424                                                         if (buflen > 0)
 425                                                         {
 426                                                                 /* ... and write it to child's stdin */
 427                                                                 if (write(wfd[1], buf, buflen) < 0)
 428                                                                         perror("write()");
 429
 430                                                                 content_length -= buflen;
 431                                                         }
 432
 433                                                         /* unexpected eof! */
 434                                                         else
 435                                                         {
 436                                                                 if (write(wfd[1], "", 0) < 0)
 437                                                                         perror("write()");
 438
 439                                                                 content_length = 0;
 440                                                         }
 441                                                 }
 442
 443                                                 /* there is no more post data, close pipe to child's stdin */
 444                                                 else if (content_length > -1)
 445                                                 {
 446                                                         close(wfd[1]);
 447                                                         content_length = -1;
 448                                                 }
 449                                         }
 450
 451                                         /* ready to read from cgi program */
 452                                         if (FD_ISSET(rfd[0], &reader))
 453                                         {
 454                                                 /* read data from child ... */
 455                                                 if ((buflen = read(rfd[0], buf, sizeof(buf))) > 0)
 456                                                 {
 457                                                         /* we have not pushed out headers yet, parse input */
 458                                                         if (!header_sent)
 459                                                         {
 460                                                                 /* head buffer not full and no end yet */
 461                                                                 if (hdrlen < sizeof(hdr))
 462                                                                 {
 463                                                                         bufoff = min(buflen, sizeof(hdr) - hdrlen);
 464                                                                         memcpy(&hdr[hdrlen], buf, bufoff);
 465                                                                         hdrlen += bufoff;
 466                                                                 }
 467                                                                 else
 468                                                                 {
 469                                                                         bufoff = 0;
 470                                                                 }
 471
 472
 473                                                                 /* try to parse header ... */
 474                                                                 if ((res = uh_cgi_header_parse(hdr, hdrlen, &hdroff)) != NULL)
 475                                                                 {
 476                                                                         /* write status */
 477                                                                         ensure_out(uh_http_sendf(cl, NULL,
 478                                                                                 "HTTP/%.1f %03d %s\r\n"
 479                                                                                 "Connection: close\r\n",
 480                                                                                 req->version, res->statuscode,
 481                                                                                 res->statusmsg));
 482
 483                                                                         /* add Content-Type if no Location or Content-Type */
 484                                                                         if( !uh_cgi_header_lookup(res, "Location") &&
 485                                                                             !uh_cgi_header_lookup(res, "Content-Type")
 486                                                                         ) {
 487                                                                                 ensure_out(uh_http_send(cl, NULL,
 488                                                                                         "Content-Type: text/plain\r\n", -1));
 489                                                                         }
 490
 491                                                                         /* if request was HTTP 1.1 we'll respond chunked */
 492                                                                         if( (req->version > 1.0) &&
 493                                                                             !uh_cgi_header_lookup(res, "Transfer-Encoding")
 494                                                                         ) {
 495                                                                                 ensure_out(uh_http_send(cl, NULL,
 496                                                                                         "Transfer-Encoding: chunked\r\n", -1));
 497                                                                         }
 498
 499                                                                         /* write headers from CGI program */
 500                                                                         foreach_header(i, res->headers)
 501                                                                         {
 502                                                                                 ensure_out(uh_http_sendf(cl, NULL, "%s: %s\r\n",
 503                                                                                         res->headers[i], res->headers[i+1]));
 504                                                                         }
 505
 506                                                                         /* terminate header */
 507                                                                         ensure_out(uh_http_send(cl, NULL, "\r\n", -1));
 508
 509                                                                         /* push out remaining head buffer */
 510                                                                         if (hdroff < hdrlen)
 511                                                                                 ensure_out(uh_http_send(cl, req, &hdr[hdroff], hdrlen - hdroff));
 512                                                                 }
 513
 514                                                                 /* ... failed and head buffer exceeded */
 515                                                                 else if (hdrlen >= sizeof(hdr))
 516                                                                 {
 517                                                                         ensure_out(uh_cgi_error_500(cl, req,
 518                                                                                 "The CGI program generated an invalid response:\n\n"));
 519
 520                                                                         ensure_out(uh_http_send(cl, req, hdr, hdrlen));
 521                                                                 }
 522
 523                                                                 /* ... failed but free buffer space, try again */
 524                                                                 else
 525                                                                 {
 526                                                                         continue;
 527                                                                 }
 528
 529                                                                 /* push out remaining read buffer */
 530                                                                 if (bufoff < buflen)
 531                                                                         ensure_out(uh_http_send(cl, req, &buf[bufoff], buflen - bufoff));
 532
 533                                                                 header_sent = 1;
 534                                                                 continue;
 535                                                         }
 536
 537
 538                                                         /* headers complete, pass through buffer to socket */
 539                                                         ensure_out(uh_http_send(cl, req, buf, buflen));
 540                                                 }
 541
 542                                                 /* looks like eof from child */
 543                                                 else
 544                                                 {
 545                                                         /* cgi script did not output useful stuff at all */
 546                                                         if (!header_sent)
 547                                                         {
 548                                                                 /* I would do this ...
 549                                                                  *
 550                                                                  *    uh_cgi_error_500(cl, req,
 551                                                                  *        "The CGI program generated an "
 552                                                                  *        "invalid response:\n\n");
 553                                                                  *
 554                                                                  * ... but in order to stay as compatible as possible,
 555                                                                  * treat whatever we got as text/plain response and
 556                                                                  * build the required headers here.
 557                                                                  */
 558
 559                                                                 ensure_out(uh_http_sendf(cl, NULL,
 560                                                                         "HTTP/%.1f 200 OK\r\n"
 561                                                                         "Content-Type: text/plain\r\n"
 562                                                                         "%s\r\n",
 563                                                                                 req->version, (req->version > 1.0)
 564                                                                                         ? "Transfer-Encoding: chunked\r\n" : ""
 565                                                                 ));
 566
 567                                                                 ensure_out(uh_http_send(cl, req, hdr, hdrlen));
 568                                                         }
 569
 570                                                         /* send final chunk if we're in chunked transfer mode */
 571                                                         ensure_out(uh_http_send(cl, req, "", 0));
 572                                                         break;
 573                                                 }
 574                                         }
 575                                 }
 576
 577                                 /* timeout exceeded or interrupted by SIGCHLD */
 578                                 else
 579                                 {
 580                                         if ((errno != EINTR) && ! header_sent)
 581                                         {
 582                                                 ensure_out(uh_http_sendhf(cl, 504, "Gateway Timeout",
 583                                                         "The CGI script took too long to produce "
 584                                                         "a response"));
 585                                         }
 586
 587                                         /* send final chunk if we're in chunked transfer mode */
 588                                         ensure_out(uh_http_send(cl, req, "", 0));
 589
 590                                         break;
 591                                 }
 592                         }
 593
 594                 out:
 595                         close(rfd[0]);
 596                         close(wfd[1]);
 597
 598                         if (!kill(child, 0))
 599                         {
 600                                 kill(child, SIGTERM);
 601                                 waitpid(child, NULL, 0);
 602                         }
 603
 604                         break;
 605         }
 606 }