/*
 * Usage: as CGI script, but called by userv
 * environment variables are USERV_U_E_...
 */
/*
 * Copyright 1996-2013,2016 Ian Jackson <ijackson@chiark.greenend.org.uk>
 * Copyright 1998 David Damerell <damerell@chiark.greenend.org.uk>
 * Copyright 1999,2003
 *    Chancellor Masters and Scholars of the University of Cambridge
 * Copyright 2010 Tony Finch <fanf@dotat.at>
 * Copyright 2013,2016 Mark Wooding <mdw@distorted.org.uk>
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with userv-utils; if not, see http://www.gnu.org/licenses/.
 */

#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <getopt.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/stat.h>

#include "ucgi.h"

static const char *const default_envok[]= {
  "AUTH_TYPE",
  "CONTENT_LENGTH",
  "CONTENT_TYPE",
  "DOCUMENT_ROOT",
  "GATEWAY_INTERFACE",
  "HTTP_ACCEPT",
  "HTTP_ACCEPT_CHARSET",
  "HTTP_ACCEPT_ENCODING",
  "HTTP_ACCEPT_LANGUAGE",
  "HTTP_CACHE_CONTROL",
  "HTTP_CONNECTION",
  "HTTP_CONTENT_ENCODING",
  "HTTP_COOKIE",
  "HTTP_DNT",
  "HTTP_HOST",
  "HTTP_KEEP_ALIVE",
  "HTTP_NEGOTIATE",
  "HTTP_PRAGMA",
  "HTTP_REFERER",
  "HTTP_USER_AGENT",
  "HTTP_VIA",
  "HTTP_X_FORWARDED_FOR",
  "HTTPS",
  "PATH_INFO",
  "PATH_TRANSLATED",
  "QUERY_STRING",
  "REDIRECT_HANDLER",
  "REDIRECT_SCRIPT_URI",
  "REDIRECT_SCRIPT_URL",
  "REDIRECT_STATUS",
  "REDIRECT_URL",
  "REMOTE_ADDR",
  "REMOTE_HOST",
  "REMOTE_USER",
  "REMOTE_IDENT",
  "REQUEST_METHOD",
  "REQUEST_URI",
  "SCRIPT_FILENAME",
  "SCRIPT_NAME",
  "SCRIPT_URI",
  "SCRIPT_URL",
  "SERVER_ADDR",
  "SERVER_ADMIN",
  "SERVER_NAME",
  "SERVER_PORT",
  "SERVER_PROTOCOL",
  "SERVER_SIGNATURE",
  "SERVER_SOFTWARE",
  "SSL_CIPHER",
  "SSL_CLIENT_S_DN",
  "SSL_CLIENT_VERIFY",
  "SSL_PROTOCOL",
  0
};

static void setenvar(const char *fulln,
		     const char *en, const char *ep, void *p) {
  xsetenv(en, ep, 1);
  unsetenv(fulln);
}

int main(int argc, char **argv) {
  char *scriptpath, *newvar;
  const char *nextslash, *lastslash, *pathi, *ev, *ev2, *scriptdir, *av;
  const char *const *envok;
  const char **arguments;
  size_t scriptdirlen, scriptpathlen, l;
  struct stat stab;
  int i, r, nargs;
  const char *filters= 0;

  ev= getenv("USERV_U_DEBUG");
  if (ev && *ev) debugmode= 1;
  
  D( if (debugmode) printf(";;; UCGITARGET\n"); )
  if (argc > MAX_ARGS) error("too many arguments", 500);

  for (;;) {
    i= getopt(argc, argv, "+e:"); if (i < 0) break;
    switch (i) {
    case 'e': filters= optarg; break;
    default: error("bad command line", 500); break;
    }
  }
  argc -= optind; argv += optind;

  if (!*argv) error("no script directory argument", 500);
  ev= getenv("HOME"); if (!ev) error("no HOME env. var", 500);
  l= strlen(*argv)+strlen(ev);
  newvar= xmalloc(l+2);
  sprintf(newvar,"%s/%s",ev,*argv);
  scriptdir= newvar;
  scriptdirlen= strlen(scriptdir);

  if (filters)
    envok= load_filters(LOADF_MUST, filters, LF_END);
  else {
    envok= load_filters(0,
			".userv/ucgitarget.env-filter",
			"/etc/userv/ucgitarget.env-filter",
			LF_END);
  }

  filter_environment(0, "USERV_U_E_", envok, default_envok, setenvar, 0);

  scriptpath= 0;
  pathi= getenv("PATH_INFO");
  if (!pathi) error("PATH_INFO not found", 500);
  lastslash= pathi;
  D( if (debugmode) {
       printf(";; find script name...\n"
	      ";;   PATH_INFO = `%s'\n",
	      pathi);
  } )
  for (;;) {
    if (*lastslash != '/') error("PATH_INFO expected slash not found", 400);
    if (lastslash[1]=='.' || lastslash[1]=='#' || !lastslash[1])
      error("bad char begin", 400);
    nextslash= strchr(lastslash+1,'/');
    if (!nextslash) nextslash= lastslash+1+strlen(lastslash+1);
    if (!nextslash) error("insufficient elements in PATH_INFO", 400);
    if (nextslash==lastslash+1) error("empty component in PATH_INFO", 400);
    if (nextslash-pathi > MAX_SCRIPTPATH_LEN)
      error("PATH_INFO script path too long", 400);
    scriptpathlen= scriptdirlen+(nextslash-pathi);
    scriptpath= xrealloc(scriptpath,scriptpathlen+1);
    strcpy(scriptpath,scriptdir);
    memcpy(scriptpath+scriptdirlen,pathi,nextslash-pathi);
    scriptpath[scriptpathlen]= 0;
    if (scriptpath[scriptpathlen-1]=='~') error("bad char end", 400);
    D( if (debugmode) printf(";;   try `%s'\n", scriptpath); )
    r= stat(scriptpath,&stab); if (r) syserror("stat script");
    if (S_ISREG(stab.st_mode)) break;
    if (!S_ISDIR(stab.st_mode)) error("script not directory or file", 500);
    lastslash= nextslash;
  }
  D( if (debugmode) printf(";;   found script: tail = `%s'\n", nextslash); )
  if (*nextslash) xsetenv("PATH_INFO",nextslash,1);
  else unsetenv("PATH_INFO");

  newvar= xmalloc(scriptpathlen+strlen(nextslash)+3);
  sprintf(newvar,"%s%s",scriptpath,nextslash);
  xsetenv("PATH_TRANSLATED",newvar,1);

  xsetenv("SCRIPT_FILENAME",scriptpath,1);

  ev= getenv("SCRIPT_NAME");
  if (ev) {
    ev2= getenv("USER"); if (!ev2) error("no USER variable", 500);
    newvar= xmalloc(strlen(ev)+2+strlen(ev2)+scriptpathlen-scriptdirlen+2);
    sprintf(newvar,"%s/~%s%s",ev,ev2,scriptpath+scriptdirlen);
    xsetenv("SCRIPT_NAME",newvar,1);
  }

  arguments= xmalloc(sizeof(const char*)*(argc+5));
  nargs= 0;
  
  arguments[nargs++]= scriptpath;
  while ((av= (*++argv))) arguments[nargs++]= av;
  arguments[nargs++]= 0;

  D( if (debugmode) {
       int i;

       printf(";; final environment...\n");
       for (i = 0; environ[i]; i++)
	 printf(";;   %s\n", environ[i]);

       printf(";; final command line...\n");
       for (i = 0; arguments[i]; i++)
	 printf(";;   %s\n", arguments[i]);
       fflush(stdout);
  } )

  execvp(scriptpath,(char*const*)arguments);
  syserror("exec script");
  return -1;
}