cgi.c

   1 /*
   2  * uhttpd - Tiny single-threaded httpd
   3  *
   4  *   Copyright (C) 2010-2013 Jo-Philipp Wich <xm@subsignal.org>
   5  *   Copyright (C) 2013 Felix Fietkau <nbd@openwrt.org>
   6  *
   7  * Permission to use, copy, modify, and/or distribute this software for any
   8  * purpose with or without fee is hereby granted, provided that the above
   9  * copyright notice and this permission notice appear in all copies.
  10  *
  11  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  12  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  13  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  14  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  15  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  16  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  17  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  18  */
  19
  20 #define _GNU_SOURCE
  21 #include <libubox/blobmsg.h>
  22 #include "uhttpd.h"
  23
  24 static LIST_HEAD(interpreters);
  25
  26 void uh_interpreter_add(const char *ext, const char *path)
  27 {
  28         struct interpreter *in;
  29         char *new_ext, *new_path;
  30
  31         in = calloc_a(sizeof(*in),
  32                 &new_ext, strlen(ext) + 1,
  33                 &new_path, strlen(path) + 1);
  34
  35         in->ext = strcpy(new_ext, ext);
  36         in->path = strcpy(new_path, path);
  37         list_add_tail(&in->list, &interpreters);
  38 }
  39
  40 static void cgi_main(struct client *cl, struct path_info *pi, char *url)
  41 {
  42         const struct interpreter *ip = pi->ip;
  43         struct env_var *var;
  44
  45         clearenv();
  46         setenv("PATH", conf.cgi_path, 1);
  47
  48         for (var = uh_get_process_vars(cl, pi); var->name; var++) {
  49                 if (!var->value)
  50                         continue;
  51
  52                 setenv(var->name, var->value, 1);
  53         }
  54
  55         if (!chdir(pi->root)) {
  56                 if (ip)
  57                         execl(ip->path, ip->path, pi->phys, NULL);
  58                 else
  59                         execl(pi->phys, pi->phys, NULL);
  60         }
  61
  62         printf("Status: 500 Internal Server Error\r\n\r\n"
  63                "Unable to launch the requested CGI program:\n"
  64                "  %s: %s\n", ip ? ip->path : pi->phys, strerror(errno));
  65 }
  66
  67 static void cgi_handle_request(struct client *cl, char *url, struct path_info *pi)
  68 {
  69         unsigned int mode = S_IFREG | S_IXOTH;
  70         char *escaped_url;
  71
  72         if (!pi->ip && !((pi->stat.st_mode & mode) == mode)) {
  73                 escaped_url = uh_htmlescape(url);
  74
  75                 uh_client_error(cl, 403, "Forbidden",
  76                                 "You don't have permission to access %s on this server.",
  77                                 escaped_url ? escaped_url : "the url");
  78
  79                 if (escaped_url)
  80                         free(escaped_url);
  81
  82                 return;
  83         }
  84
  85         if (!uh_create_process(cl, pi, url, cgi_main)) {
  86                 uh_client_error(cl, 500, "Internal Server Error",
  87                                 "Failed to create CGI process: %s", strerror(errno));
  88                 return;
  89         }
  90
  91         return;
  92 }
  93
  94 static bool check_cgi_path(struct path_info *pi, const char *url)
  95 {
  96         struct interpreter *ip;
  97         const char *path = pi->phys;
  98         int path_len = strlen(path);
  99
 100         list_for_each_entry(ip, &interpreters, list) {
 101                 int len = strlen(ip->ext);
 102
 103                 if (len >= path_len)
 104                         continue;
 105
 106                 if (strcmp(path + path_len - len, ip->ext) != 0)
 107                         continue;
 108
 109                 pi->ip = ip;
 110                 return true;
 111         }
 112
 113         pi->ip = NULL;
 114
 115         if (conf.cgi_docroot_path)
 116                 return uh_path_match(conf.cgi_docroot_path, pi->phys);
 117
 118         return false;
 119 }
 120
 121 struct dispatch_handler cgi_dispatch = {
 122         .script = true,
 123         .check_path = check_cgi_path,
 124         .handle_request = cgi_handle_request,
 125 };