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

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