Root/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
23static 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
108static 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
121static 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
138void 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
607

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