networking/httpd_ssi.c

   1 /*
   2  * Copyright (c) 2009 Denys Vlasenko <vda.linux@googlemail.com>
   3  *
   4  * Licensed under GPLv2, see file LICENSE in this source tree.
   5  */
   6
   7 /*
   8  * This program is a CGI application. It processes server-side includes:
   9  * <!--#include file="file.html" -->
  10  *
  11  * Usage: put these lines in httpd.conf:
  12  *
  13  * *.html:/bin/httpd_ssi
  14  * *.htm:/bin/httpd_ssi
  15  */
  16
  17 /* Build a-la
  18 i486-linux-uclibc-gcc \
  19 -static -static-libgcc \
  20 -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 \
  21 -Wall -Wshadow -Wwrite-strings -Wundef -Wstrict-prototypes -Werror \
  22 -Wold-style-definition -Wdeclaration-after-statement -Wno-pointer-sign \
  23 -Wmissing-prototypes -Wmissing-declarations \
  24 -Os -fno-builtin-strlen -finline-limit=0 -fomit-frame-pointer \
  25 -ffunction-sections -fdata-sections -fno-guess-branch-probability \
  26 -funsigned-char \
  27 -falign-functions=1 -falign-jumps=1 -falign-labels=1 -falign-loops=1 \
  28 -march=i386 -mpreferred-stack-boundary=2 \
  29 -Wl,-Map -Wl,link.map -Wl,--warn-common -Wl,--sort-common -Wl,--gc-sections \
  30 httpd_ssi.c -o httpd_ssi
  31 */
  32
  33 /* Size (i386, static uclibc, approximate):
  34  * text    data     bss     dec     hex filename
  35  * 9487     160   68552   78199   13177 httpd_ssi
  36  *
  37  * Note: it wouldn't be too hard to get rid of stdio and strdup,
  38  * (especially that fgets() mangles NULs...)
  39  */
  40
  41 #include <sys/types.h>
  42 #include <sys/stat.h>
  43 #include <errno.h>
  44 #include <fcntl.h>
  45 #include <stdint.h>
  46 #include <stdlib.h>
  47 #include <string.h>
  48 #include <unistd.h>
  49 #include <stdio.h>
  50 #include <dirent.h>
  51 #include <time.h>
  52
  53 static char* skip_whitespace(char *s)
  54 {
  55         while (*s == ' ' || *s == '\t') ++s;
  56
  57         return s;
  58 }
  59
  60 static char line[64 * 1024];
  61
  62 static void process_includes(const char *filename)
  63 {
  64         int curdir_fd;
  65         char *end;
  66         FILE *fp = fopen(filename, "r");
  67         if (!fp)
  68                 exit(1);
  69
  70         /* Ensure that nested includes are relative:
  71          * if we include a/1.htm and it includes b/2.htm,
  72          * we need to include a/b/2.htm, not b/2.htm
  73          */
  74         curdir_fd = -1;
  75         end = strrchr(filename, '/');
  76         if (end) {
  77                 curdir_fd = open(".", O_RDONLY);
  78                 /* *end = '\0' would mishandle "/file.htm" */
  79                 end[1] = '\0';
  80                 chdir(filename);
  81         }
  82
  83 #define INCLUDE "<!--#include"
  84         while (fgets(line, sizeof(line), fp)) {
  85                 unsigned preceding_len;
  86                 char *include_directive;
  87
  88                 include_directive = strstr(line, INCLUDE);
  89                 if (!include_directive) {
  90                         fputs(line, stdout);
  91                         continue;
  92                 }
  93                 preceding_len = include_directive - line;
  94                 if (memchr(line, '\"', preceding_len)
  95                  || memchr(line, '\'', preceding_len)
  96                 ) {
  97                         /* INCLUDE string may be inside "str" or 'str',
  98                          * ignore it */
  99                         fputs(line, stdout);
 100                         continue;
 101                 }
 102                 /* Small bug: we accept #includefile="file" too */
 103                 include_directive = skip_whitespace(include_directive + sizeof(INCLUDE)-1);
 104                 if (strncmp(include_directive, "file=\"", 6) != 0) {
 105                         /* "<!--#include virtual=..."? - not supported */
 106                         fputs(line, stdout);
 107                         continue;
 108                 }
 109                 include_directive += 6; /* now it points to file name */
 110                 end = strchr(include_directive, '\"');
 111                 if (!end) {
 112                         fputs(line, stdout);
 113                         continue;
 114                 }
 115                 /* We checked that this is a valid include directive */
 116
 117                 /* Print everything before directive */
 118                 if (preceding_len) {
 119                         line[preceding_len] = '\0';
 120                         fputs(line, stdout);
 121                 }
 122                 /* Save everything after directive */
 123                 *end++ = '\0';
 124                 end = strchr(end, '>');
 125                 if (end)
 126                         end = strdup(end + 1);
 127
 128                 /* FIXME:
 129                  * (1) are relative paths with /../ etc ok?
 130                  * (2) what to do with absolute paths?
 131                  * are they relative to doc root or to real root?
 132                  */
 133                 process_includes(include_directive);
 134
 135                 /* Print everything after directive */
 136                 if (end) {
 137                         fputs(end, stdout);
 138                         free(end);
 139                 }
 140         }
 141         if (curdir_fd >= 0)
 142                 fchdir(curdir_fd);
 143         fclose(fp);
 144 }
 145
 146 int main(int argc, char *argv[])
 147 {
 148         if (!argv[1])
 149                 return 1;
 150
 151         /* Seen from busybox.net's Apache:
 152          * HTTP/1.1 200 OK
 153          * Date: Thu, 10 Sep 2009 18:23:28 GMT
 154          * Server: Apache
 155          * Accept-Ranges: bytes
 156          * Connection: close
 157          * Content-Type: text/html
 158          */
 159         fputs(
 160                 /* "Date: Thu, 10 Sep 2009 18:23:28 GMT\r\n" */
 161                 /* "Server: Apache\r\n" */
 162                 /* "Accept-Ranges: bytes\r\n" - do we really accept bytes?! */
 163                 "Connection: close\r\n"
 164                 "Content-Type: text/html\r\n"
 165                 "\r\n",
 166                 stdout
 167         );
 168         process_includes(argv[1]);
 169         return 0;
 170 }