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openwrt/package/uhttpd/src/uhttpd-cgi.c

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/*
* uhttpd - Tiny single-threaded httpd - CGI handler
*
* Copyright (C) 2010 Jo-Philipp Wich <xm@subsignal.org>
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "uhttpd.h"
#include "uhttpd-utils.h"
#include "uhttpd-cgi.h"
static struct http_response * uh_cgi_header_parse(char *buf, int len, int *off)
{
char *bufptr = NULL;
char *hdrname = NULL;
int hdrcount = 0;
int pos = 0;
static struct http_response res;
if( ((bufptr = strfind(buf, len, "\r\n\r\n", 4)) != NULL) ||
((bufptr = strfind(buf, len, "\n\n", 2)) != NULL)
) {
*off = (int)(bufptr - buf) + ((bufptr[0] == '\r') ? 4 : 2);
memset(&res, 0, sizeof(res));
res.statuscode = 200;
res.statusmsg = "OK";
bufptr = &buf[0];
for( pos = 0; pos < len; pos++ )
{
if( !hdrname && (buf[pos] == ':') )
{
buf[pos++] = 0;
if( (pos < len) && (buf[pos] == ' ') )
pos++;
if( pos < len )
{
hdrname = bufptr;
bufptr = &buf[pos];
}
}
else if( (buf[pos] == '\r') || (buf[pos] == '\n') )
{
buf[pos++] = 0;
if( ! hdrname )
break;
if( (pos < len) && (buf[pos] == '\n') )
pos++;
if( pos <= len )
{
if( (hdrcount + 1) < array_size(res.headers) )
{
if( ! strcasecmp(hdrname, "Status") )
{
res.statuscode = atoi(bufptr);
if( res.statuscode < 100 )
res.statuscode = 200;
if( ((bufptr = strchr(bufptr, ' ')) != NULL) && (&bufptr[1] != 0) )
res.statusmsg = &bufptr[1];
}
else
{
res.headers[hdrcount++] = hdrname;
res.headers[hdrcount++] = bufptr;
}
bufptr = &buf[pos];
hdrname = NULL;
}
else
{
return NULL;
}
}
}
}
return &res;
}
return NULL;
}
static char * uh_cgi_header_lookup(struct http_response *res, const char *hdrname)
{
int i;
foreach_header(i, res->headers)
{
if( ! strcasecmp(res->headers[i], hdrname) )
return res->headers[i+1];
}
return NULL;
}
static int uh_cgi_error_500(struct client *cl, struct http_request *req, const char *message)
{
if( uh_http_sendf(cl, NULL,
"HTTP/%.1f 500 Internal Server Error\r\n"
"Content-Type: text/plain\r\n%s\r\n",
req->version,
(req->version > 1.0)
? "Transfer-Encoding: chunked\r\n" : ""
) >= 0
) {
return uh_http_send(cl, req, message, -1);
}
return -1;
}
void uh_cgi_request(struct client *cl, struct http_request *req, struct path_info *pi)
{
int i, hdroff, bufoff;
int hdrlen = 0;
int buflen = 0;
int fd_max = 0;
int content_length = 0;
int header_sent = 0;
int rfd[2] = { 0, 0 };
int wfd[2] = { 0, 0 };
char buf[UH_LIMIT_MSGHEAD];
char hdr[UH_LIMIT_MSGHEAD];
pid_t child;
fd_set reader;
fd_set writer;
struct sigaction sa;
struct timeval timeout;
struct http_response *res;
/* spawn pipes for me->child, child->me */
if( (pipe(rfd) < 0) || (pipe(wfd) < 0) )
{
uh_http_sendhf(cl, 500, "Internal Server Error",
"Failed to create pipe: %s", strerror(errno));
if( rfd[0] > 0 ) close(rfd[0]);
if( rfd[1] > 0 ) close(rfd[1]);
if( wfd[0] > 0 ) close(wfd[0]);
if( wfd[1] > 0 ) close(wfd[1]);
return;
}
/* fork off child process */
switch( (child = fork()) )
{
/* oops */
case -1:
uh_http_sendhf(cl, 500, "Internal Server Error",
"Failed to fork child: %s", strerror(errno));
return;
/* exec child */
case 0:
/* restore SIGTERM */
sa.sa_flags = 0;
sa.sa_handler = SIG_DFL;
sigemptyset(&sa.sa_mask);
sigaction(SIGTERM, &sa, NULL);
/* close loose pipe ends */
close(rfd[0]);
close(wfd[1]);
/* patch stdout and stdin to pipes */
dup2(rfd[1], 1);
dup2(wfd[0], 0);
/* check for regular, world-executable file */
if( (pi->stat.st_mode & S_IFREG) &&
(pi->stat.st_mode & S_IXOTH)
) {
/* build environment */
clearenv();
/* common information */
setenv("GATEWAY_INTERFACE", "CGI/1.1", 1);
setenv("SERVER_SOFTWARE", "uHTTPd", 1);
setenv("PATH", "/sbin:/usr/sbin:/bin:/usr/bin", 1);
#ifdef HAVE_TLS
/* https? */
if( cl->tls )
setenv("HTTPS", "on", 1);
#endif
/* addresses */
setenv("SERVER_NAME", sa_straddr(&cl->servaddr), 1);
setenv("SERVER_ADDR", sa_straddr(&cl->servaddr), 1);
setenv("SERVER_PORT", sa_strport(&cl->servaddr), 1);
setenv("REMOTE_HOST", sa_straddr(&cl->peeraddr), 1);
setenv("REMOTE_ADDR", sa_straddr(&cl->peeraddr), 1);
setenv("REMOTE_PORT", sa_strport(&cl->peeraddr), 1);
/* path information */
setenv("SCRIPT_NAME", pi->name, 1);
setenv("SCRIPT_FILENAME", pi->phys, 1);
setenv("DOCUMENT_ROOT", pi->root, 1);
setenv("QUERY_STRING", pi->query ? pi->query : "", 1);
if( pi->info )
setenv("PATH_INFO", pi->info, 1);
/* http version */
if( req->version > 1.0 )
setenv("SERVER_PROTOCOL", "HTTP/1.1", 1);
else
setenv("SERVER_PROTOCOL", "HTTP/1.0", 1);
/* request method */
switch( req->method )
{
case UH_HTTP_MSG_GET:
setenv("REQUEST_METHOD", "GET", 1);
break;
case UH_HTTP_MSG_HEAD:
setenv("REQUEST_METHOD", "HEAD", 1);
break;
case UH_HTTP_MSG_POST:
setenv("REQUEST_METHOD", "POST", 1);
break;
}
/* request url */
setenv("REQUEST_URI", req->url, 1);
/* remote user */
if( req->realm )
setenv("REMOTE_USER", req->realm->user, 1);
/* request message headers */
foreach_header(i, req->headers)
{
if( ! strcasecmp(req->headers[i], "Accept") )
setenv("HTTP_ACCEPT", req->headers[i+1], 1);
else if( ! strcasecmp(req->headers[i], "Accept-Charset") )
setenv("HTTP_ACCEPT_CHARSET", req->headers[i+1], 1);
else if( ! strcasecmp(req->headers[i], "Accept-Encoding") )
setenv("HTTP_ACCEPT_ENCODING", req->headers[i+1], 1);
else if( ! strcasecmp(req->headers[i], "Accept-Language") )
setenv("HTTP_ACCEPT_LANGUAGE", req->headers[i+1], 1);
else if( ! strcasecmp(req->headers[i], "Authorization") )
setenv("HTTP_AUTHORIZATION", req->headers[i+1], 1);
else if( ! strcasecmp(req->headers[i], "Connection") )
setenv("HTTP_CONNECTION", req->headers[i+1], 1);
else if( ! strcasecmp(req->headers[i], "Cookie") )
setenv("HTTP_COOKIE", req->headers[i+1], 1);
else if( ! strcasecmp(req->headers[i], "Host") )
setenv("HTTP_HOST", req->headers[i+1], 1);
else if( ! strcasecmp(req->headers[i], "Referer") )
setenv("HTTP_REFERER", req->headers[i+1], 1);
else if( ! strcasecmp(req->headers[i], "User-Agent") )
setenv("HTTP_USER_AGENT", req->headers[i+1], 1);
else if( ! strcasecmp(req->headers[i], "Content-Type") )
setenv("CONTENT_TYPE", req->headers[i+1], 1);
else if( ! strcasecmp(req->headers[i], "Content-Length") )
setenv("CONTENT_LENGTH", req->headers[i+1], 1);
}
/* execute child code ... */
if( chdir(pi->root) )
perror("chdir()");
execl(pi->phys, pi->phys, NULL);
/* in case it fails ... */
printf(
"Status: 500 Internal Server Error\r\n\r\n"
"Unable to launch the requested CGI program:\n"
" %s: %s\n",
pi->phys, strerror(errno)
);
}
/* 403 */
else
{
printf(
"Status: 403 Forbidden\r\n\r\n"
"Access to this resource is forbidden\n"
);
}
close(wfd[0]);
close(rfd[1]);
exit(0);
break;
/* parent; handle I/O relaying */
default:
/* close unneeded pipe ends */
close(rfd[1]);
close(wfd[0]);
/* max watch fd */
fd_max = max(rfd[0], wfd[1]) + 1;
/* find content length */
if( req->method == UH_HTTP_MSG_POST )
{
foreach_header(i, req->headers)
{
if( ! strcasecmp(req->headers[i], "Content-Length") )
{
content_length = atoi(req->headers[i+1]);
break;
}
}
}
memset(hdr, 0, sizeof(hdr));
timeout.tv_sec = cl->server->conf->script_timeout;
timeout.tv_usec = 0;
#define ensure(x) \
do { if( x < 0 ) goto out; } while(0)
/* I/O loop, watch our pipe ends and dispatch child reads/writes from/to socket */
while( 1 )
{
FD_ZERO(&reader);
FD_ZERO(&writer);
FD_SET(rfd[0], &reader);
FD_SET(wfd[1], &writer);
/* wait until we can read or write or both */
if( select_intr(fd_max, &reader,
(content_length > -1) ? &writer : NULL, NULL,
(header_sent < 1) ? &timeout : NULL) > 0
) {
/* ready to write to cgi program */
if( FD_ISSET(wfd[1], &writer) )
{
/* there is unread post data waiting */
if( content_length > 0 )
{
/* read it from socket ... */
if( (buflen = uh_tcp_recv(cl, buf, min(content_length, sizeof(buf)))) > 0 )
{
/* ... and write it to child's stdin */
if( write(wfd[1], buf, buflen) < 0 )
perror("write()");
content_length -= buflen;
}
/* unexpected eof! */
else
{
if( write(wfd[1], "", 0) < 0 )
perror("write()");
content_length = 0;
}
}
/* there is no more post data, close pipe to child's stdin */
else if( content_length > -1 )
{
close(wfd[1]);
content_length = -1;
}
}
/* ready to read from cgi program */
if( FD_ISSET(rfd[0], &reader) )
{
/* read data from child ... */
if( (buflen = read(rfd[0], buf, sizeof(buf))) > 0 )
{
/* we have not pushed out headers yet, parse input */
if( ! header_sent )
{
/* head buffer not full and no end yet */
if( hdrlen < sizeof(hdr) )
{
bufoff = min(buflen, sizeof(hdr) - hdrlen);
memcpy(&hdr[hdrlen], buf, bufoff);
hdrlen += bufoff;
}
else
{
bufoff = 0;
}
/* try to parse header ... */
if( (res = uh_cgi_header_parse(hdr, hdrlen, &hdroff)) != NULL )
{
/* write status */
ensure(uh_http_sendf(cl, NULL,
"HTTP/%.1f %03d %s\r\n"
"Connection: close\r\n",
req->version, res->statuscode,
res->statusmsg));
/* add Content-Type if no Location or Content-Type */
if( !uh_cgi_header_lookup(res, "Location") &&
!uh_cgi_header_lookup(res, "Content-Type")
) {
ensure(uh_http_send(cl, NULL,
"Content-Type: text/plain\r\n", -1));
}
/* if request was HTTP 1.1 we'll respond chunked */
if( (req->version > 1.0) &&
!uh_cgi_header_lookup(res, "Transfer-Encoding")
) {
ensure(uh_http_send(cl, NULL,
"Transfer-Encoding: chunked\r\n", -1));
}
/* write headers from CGI program */
foreach_header(i, res->headers)
{
ensure(uh_http_sendf(cl, NULL, "%s: %s\r\n",
res->headers[i], res->headers[i+1]));
}
/* terminate header */
ensure(uh_http_send(cl, NULL, "\r\n", -1));
/* push out remaining head buffer */
if( hdroff < hdrlen )
ensure(uh_http_send(cl, req, &hdr[hdroff], hdrlen - hdroff));
}
/* ... failed and head buffer exceeded */
else if( hdrlen >= sizeof(hdr) )
{
ensure(uh_cgi_error_500(cl, req,
"The CGI program generated an invalid response:\n\n"));
ensure(uh_http_send(cl, req, hdr, hdrlen));
}
/* ... failed but free buffer space, try again */
else
{
continue;
}
/* push out remaining read buffer */
if( bufoff < buflen )
ensure(uh_http_send(cl, req, &buf[bufoff], buflen - bufoff));
header_sent = 1;
continue;
}
/* headers complete, pass through buffer to socket */
ensure(uh_http_send(cl, req, buf, buflen));
}
/* looks like eof from child */
else
{
/* cgi script did not output useful stuff at all */
if( ! header_sent )
{
/* I would do this ...
*
* uh_cgi_error_500(cl, req,
* "The CGI program generated an "
* "invalid response:\n\n");
*
* ... but in order to stay as compatible as possible,
* treat whatever we got as text/plain response and
* build the required headers here.
*/
ensure(uh_http_sendf(cl, NULL,
"HTTP/%.1f 200 OK\r\n"
"Content-Type: text/plain\r\n"
"%s\r\n",
req->version, (req->version > 1.0)
? "Transfer-Encoding: chunked\r\n" : ""
));
ensure(uh_http_send(cl, req, hdr, hdrlen));
}
/* send final chunk if we're in chunked transfer mode */
ensure(uh_http_send(cl, req, "", 0));
break;
}
}
}
/* timeout exceeded or interrupted by SIGCHLD */
else
{
if( (errno != EINTR) && ! header_sent )
{
ensure(uh_http_sendhf(cl, 504, "Gateway Timeout",
"The CGI script took too long to produce "
"a response"));
}
/* send final chunk if we're in chunked transfer mode */
ensure(uh_http_send(cl, req, "", 0));
break;
}
}
out:
close(rfd[0]);
close(wfd[1]);
if( !kill(child, 0) )
{
kill(child, SIGTERM);
waitpid(child, NULL, 0);
}
break;
}
}
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