/*
    Posadis - A DNS Server
    A DNS file server using the Posadis server library
    Copyright (C) 2002  Meilof Veeningen <meilof@users.sourceforge.net>

    This program 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 2 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 this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#define POS_DEFAULTLOG
#define POS_DEFAULTLOG_STDERR
#define POS_DEFAULTLOG_SYSLOG
#define POS_DEFAULTLOG_FILE

#include <poslib/server/server.h>

#include <unistd.h>
#include <stdlib.h>
#include <signal.h>
#include <pthread.h>
#include <sys/types.h>
#include <dirent.h>
#include <errno.h>

DnsMessage *my_handle_query(pending_query *query);

void cleanup(int sig) {
  pos_setquitflag();
}

char *path;

int main(int argc, char **argv) {
  _addr a;

  try {
    /* get command-line arguments */
    if (argc == 2) {
      if (argv[1][0] == '@') {
        txt_to_addr(&a, argv[1] + 1);
        path = ".";
      } else {
        path = argv[1];
        txt_to_addr(&a, "0.0.0.0");
      }
    } else if (argc == 3 && argv[1][0] == '@') {
      /* address given */
      txt_to_addr(&a, argv[1] + 1);
      path = argv[2];      
    } else if (argc != 1) {
      printf("Usage: fileserver [@interface] [dir]\n");
      return 1;
    } else {
      path = "."; /* current directory */
      txt_to_addr(&a, "0.0.0.0");
    }

    if (chdir(path) < 0) {
      perror("Could not chdir to exported directory");
      return 1;
    }

    /* bring up posadis */
    servers.push_front(ServerSocket(ss_udp, udpcreateserver(&a)));
    servers.push_front(ServerSocket(ss_tcp, tcpcreateserver(&a)));

    pos_log(context_none, log_info, "Posadis fileserver [%s] starting up...", path);

    signal(SIGINT, cleanup);
    signal(SIGTERM, cleanup);

    handle_query = my_handle_query;
    posserver_run();
  } catch (PException p) {
    printf("Fatal exception: %s\n", p.message);
    return 1;
  }

  return 0;
}

/* the entry function which will handle all queries */

DnsMessage *my_handle_query(pending_query *query) {
  DnsMessage *a = new DnsMessage();
  DnsQuestion q;
  DnsRR rr;
  a->ID = query->message->ID;

  if (query->message->questions.begin() == query->message->questions.end()) {
    a->RCODE = RCODE_QUERYERR;
    return a;
  }
  q = *query->message->questions.begin();

  /* now, map the domain name to a file name */
  stl_string fname = "";
  stl_string substr;
  int x, n;

  n = q.QNAME.nlabels();
  for (x = n - 1; x >= 0; x--) {
    if (!fname.empty()) fname += "/";
    substr = q.QNAME.label(x);
    if (substr.find("/") != string::npos) substr = substr.replace(substr.find("/"), 1, ".");
    fname += substr;
  }

  /* check for some common pitfalls */
  if (fname.find("..") != string::npos || fname[0] == '/') {
    a->RCODE = RCODE_QUERYERR;
    return a;
  }

  /* see if we have a directory */
  DIR *dir = opendir(fname.c_str()), *d2;
  struct dirent *info;
  char curfname[PATH_MAX];
  if (dir) {
    /* yes! */
    while ((info = readdir(dir)) != NULL) {
      if (strlen(info->d_name) <= 254 &&
          strlen(info->d_name) + strlen(fname.c_str()) + 2 <= PATH_MAX) {
        strcpy(curfname, fname.c_str());
        strcat(curfname, "/");
        strcat(curfname, info->d_name);
        d2 = opendir(curfname);
        strcpy(curfname, info->d_name);
        if (d2) {
          strcat(curfname, "/");
          closedir(d2);
        }
        rr = DnsRR(q.QNAME, DNS_TYPE_TXT, CLASS_IN, 3600);
        rr.RDLENGTH = strlen(curfname) + 1;
        rr.RDATA = (char *)malloc(rr.RDLENGTH);
        rr.RDATA[0] = strlen(curfname);
        memcpy(rr.RDATA + 1, curfname, strlen(curfname));
        a->answers.push_back(rr);
      }
    }
    closedir(dir);
  } else {
    /* try to open file */
    FILE *f = fopen(fname.c_str(), "r");
    int len;
    if (f) {
      fseek(f, 0, SEEK_END);
      len = ftell(f);
      fseek(f, 0, SEEK_SET);
      if (len <= 65000) {
        rr = DnsRR(q.QNAME, DNS_TYPE_NULL, CLASS_IN, 3600);
        rr.RDLENGTH = len;
        rr.RDATA = (char *)malloc(len);
        fread(rr.RDATA, 1, len, f);
        a->answers.push_back(rr);
      } else {
        a->TC = true;
      }
      fclose(f);
    } else {
      if (f) fclose(f);
      a->RCODE = RCODE_NXDOMAIN;
    }
  }
  return a;
}