opentracker/opentracker.c

/* This software was written by Dirk Engling <erdgeist@erdgeist.org> 
   It is considered beerware. Prost. Skol. Cheers or whatever.
   Some of the stuff below is stolen from Fefes example libowfat httpd.
*/

#include "socket.h"
#include "io.h"
#include "buffer.h"
#include "array.h"
#include "byte.h"
#include "case.h"
#include "fmt.h"
#include "str.h"
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <stdlib.h>
#include <errno.h>
#include <signal.h>
#include <stdio.h>

#include "trackerlogic.h"
#include "scan_urlencoded_query.h"

unsigned int const OT_CLIENT_TIMEOUT = 15;
unsigned int const OT_CLIENT_TIMEOUT_CHECKINTERVAL = 5;

static unsigned int ot_overall_connections = 0;
static time_t ot_start_time;
static const size_t SUCCESS_HTTP_HEADER_LENGTH = 80;
static const size_t SUCCESS_HTTP_SIZE_OFF = 17;
/* To always have space for error messages ;) */
static char static_reply[8192];

static void carp(const char* routine) {
  buffer_puts(buffer_2,routine);
  buffer_puts(buffer_2,": ");
  buffer_puterror(buffer_2);
  buffer_putnlflush(buffer_2);
}

static void panic(const char* routine) {
  carp(routine);
  exit(111);
}

struct http_data {
  array r;
  unsigned char ip[4];
};

int header_complete(struct http_data* r) {
  int l = array_bytes(&r->r), i;
  const char* c = array_start(&r->r);

  for (i=0; i+1<l; ++i) {
    if (c[i]=='\n' && c[i+1]=='\n') return i+2;
    if (i+3<l && c[i]=='\r' && c[i+1]=='\n' && c[i+2]=='\r' && c[i+3]=='\n') return i+4;
  }
  return 0;
}

/* whoever sends data is not interested in its input-array */
void senddata(int64 s, struct http_data* h, char *buffer, size_t size ) {
  size_t written_size;

  if( h ) array_reset(&h->r);
  written_size = write( s, buffer, size );
  if( ( written_size < 0 ) || ( written_size == size ) ) {
    free(h); io_close( s );
  } else {
    /* here we would take a copy of the buffer and remember it */
    fprintf( stderr, "Should have handled this.\n" );
    free(h); io_close( s );
  }
}

void httperror(int64 s,struct http_data* h,const char* title,const char* message) {
  size_t reply_size = sprintf( static_reply, "HTTP/1.0 %s\r\nContent-Type: text/html\r\nConnection: close\r\nContent-Length: %zd\r\n\r\n<title>%s</title>\n",
                        title, strlen(message)+strlen(title)+16-4,title+4);
  senddata(s,h,static_reply,reply_size);
}

const char* http_header(struct http_data* r,const char* h) {
  int i, l = array_bytes(&r->r);
  int sl = strlen(h);
  const char* c = array_start(&r->r);

  for (i=0; i+sl+2<l; ++i) {
    if (c[i]=='\n' && case_equalb(c+i+1,sl,h) && c[i+sl+1]==':') {
      c+=i+sl+1;
      if (*c==' ' || *c=='\t') ++c;
      return c;
    }
    return 0;
  }
  return 0;
}

void httpresponse(int64 s,struct http_data* h)
{
  char       *c, *data;
  ot_peer     peer;
  ot_torrent *torrent;
  ot_hash    *hash = NULL;
  int         numwant, tmp, scanon;
  unsigned short port = htons(6881);
  size_t      reply_size = 0;

  array_cat0(&h->r);
  c = array_start(&h->r);

  if (byte_diff(c,4,"GET ")) {
e400:
    return httperror(s,h,"400 Invalid Request","This server only understands GET.");
  }

  c+=4;
  for (data=c; *data!=' '&&*data!='\t'&&*data!='\n'&&*data!='\r'; ++data) ;

  if (*data!=' ') goto e400;
  *data=0;
  if (c[0]!='/') goto e404;
  while (*c=='/') ++c;

  switch( scan_urlencoded_query( &c, data = c, SCAN_PATH ) ) {
  case 6: /* scrape ? */
    if (byte_diff(data,6,"scrape"))
      goto e404;
    scanon = 1;

    while( scanon ) {
      switch( scan_urlencoded_query( &c, data = c, SCAN_SEARCHPATH_PARAM ) ) {
      case -2: /* terminator */
        scanon = 0;
        break;
      case -1: /* error */
        goto e404;
      case 9:
        if(byte_diff(data,9,"info_hash")) {
          scan_urlencoded_query( &c, NULL, SCAN_SEARCHPATH_VALUE );
          continue;
        }
        /* ignore this, when we have less than 20 bytes */
        if( scan_urlencoded_query( &c, data = c, SCAN_SEARCHPATH_VALUE ) != 20 ) {
e400_param:
          return httperror(s,h,"400 Invalid Request","Invalid parameter");
        }
        hash = (ot_hash*)data; /* Fall through intended */
        break;
      default:
        scan_urlencoded_query( &c, NULL, SCAN_SEARCHPATH_VALUE );
        break;
      }
    }

    /* Scanned whole query string, wo */
    if( !hash )
      return httperror(s,h,"400 Invalid Request","This server only serves specific scrapes.");

    /* Enough for http header + whole scrape string */
    if( ( reply_size = return_scrape_for_torrent( hash, SUCCESS_HTTP_HEADER_LENGTH + static_reply ) ) <= 0 )
      goto e500;
    break;
  case 8: 
    if( byte_diff(data,8,"announce"))
      goto e404;

    OT_SETIP( &peer, h->ip);
    OT_SETPORT( &peer, &port );
    OT_FLAG( &peer ) = 0;
    numwant = 50;
    scanon = 1;

    while( scanon ) {
      switch( scan_urlencoded_query( &c, data = c, SCAN_SEARCHPATH_PARAM ) ) {
      case -2: /* terminator */
        scanon = 0;
        break;
      case -1: /* error */
        goto e404;
#ifdef WANT_IP_FROM_QUERY_STRING
      case 2:
        if(!byte_diff(data,2,"ip")) {
          size_t len = scan_urlencoded_query( &c, data = c, SCAN_SEARCHPATH_VALUE );
          unsigned char ip[4];
          if( ( len <= 0 ) || scan_fixed_ip( data, len, ip ) ) goto e400_param;
          OT_SETIP ( &peer, ip );
       } else
          scan_urlencoded_query( &c, NULL, SCAN_SEARCHPATH_VALUE );
       break;
#endif
      case 4:
        if(!byte_diff(data,4,"port")) {
          size_t len = scan_urlencoded_query( &c, data = c, SCAN_SEARCHPATH_VALUE );
          if( ( len <= 0 ) || scan_fixed_int( data, len, &tmp ) || ( tmp > 0xffff ) ) goto e400_param;
          port = htons( tmp ); OT_SETPORT ( &peer, &port );
        } else if(!byte_diff(data,4,"left")) {
          size_t len = scan_urlencoded_query( &c, data = c, SCAN_SEARCHPATH_VALUE );
          if( ( len <= 0 ) || scan_fixed_int( data, len, &tmp ) ) goto e400_param;
          if( !tmp ) OT_FLAG( &peer ) |= PEER_FLAG_SEEDING;
        } else
          scan_urlencoded_query( &c, NULL, SCAN_SEARCHPATH_VALUE );
        break;
      case 5:
        if(byte_diff(data,5,"event"))
          scan_urlencoded_query( &c, NULL, SCAN_SEARCHPATH_VALUE );
        else switch( scan_urlencoded_query( &c, data = c, SCAN_SEARCHPATH_VALUE ) ) {
        case -1:
          goto e400_param;
        case 7:
          if(!byte_diff(data,7,"stopped")) OT_FLAG( &peer ) |= PEER_FLAG_STOPPED;
          break;
        case 9:
          if(!byte_diff(data,9,"complete")) OT_FLAG( &peer ) |= PEER_FLAG_COMPLETED;
        default: /* Fall through intended */
          break;
        }
        break;
      case 7:
        if(!byte_diff(data,7,"numwant")) {
          size_t len = scan_urlencoded_query( &c, data = c, SCAN_SEARCHPATH_VALUE );
          if( ( len <= 0 ) || scan_fixed_int( data, len, &numwant ) ) goto e400_param;
          if( numwant > 200 ) numwant = 200;
        } else if(!byte_diff(data,7,"compact")) {
          size_t len = scan_urlencoded_query( &c, data = c, SCAN_SEARCHPATH_VALUE );
          if( ( len <= 0 ) || scan_fixed_int( data, len, &tmp ) ) goto e400_param;
          if( !tmp )
            return httperror(s,h,"400 Invalid Request","This server only delivers compact results.");
        } else
          scan_urlencoded_query( &c, NULL, SCAN_SEARCHPATH_VALUE );
        break;
      case 9:
        if(byte_diff(data,9,"info_hash")) {
          scan_urlencoded_query( &c, NULL, SCAN_SEARCHPATH_VALUE );
          continue;
        }
        /* ignore this, when we have less than 20 bytes */
        if( scan_urlencoded_query( &c, data = c, SCAN_SEARCHPATH_VALUE ) != 20 )
          goto e400;
        hash = (ot_hash*)data;
        break;
      default:
        scan_urlencoded_query( &c, NULL, SCAN_SEARCHPATH_VALUE );
        break;
      }
    }

    /* Scanned whole query string */
    if( !hash ) goto e400;

    if( OT_FLAG( &peer ) & PEER_FLAG_STOPPED ) {
      remove_peer_from_torrent( hash, &peer );
      memmove( static_reply + SUCCESS_HTTP_HEADER_LENGTH, "d15:warning message4:Okaye", reply_size = 26 );
    } else {
      torrent = add_peer_to_torrent( hash, &peer );
      if( !torrent ) {
e500:
        return httperror(s,h,"500 Internal Server Error","A server error has occured. Please retry later.");
      }
      if( ( reply_size = return_peers_for_torrent( torrent, numwant, SUCCESS_HTTP_HEADER_LENGTH + static_reply ) ) <= 0 )
        goto e500;
    }
    break;
  case 11:
    if( byte_diff(data,11,"mrtg_scrape"))
      goto e404;
    { 
      time_t seconds_elapsed = time( NULL ) - ot_start_time;
      reply_size = sprintf( static_reply + SUCCESS_HTTP_HEADER_LENGTH, 
                            "%i\n%i\nUp: %i seconds (%i hours)\nPretuned by german engineers, currently handling %i connections per second.",
                            ot_overall_connections, ot_overall_connections, (int)seconds_elapsed,
                            (int)(seconds_elapsed / 3600), ot_overall_connections / ( seconds_elapsed ? seconds_elapsed : 1 ) );
    }
    break;
  default: /* neither *scrape nor announce */
e404:
    return httperror(s,h,"404 Not Found","No such file or directory.");
  }

  if( reply_size ) {
    /* This one is rather ugly, so I take you step by step through it.

       1. In order to avoid having two buffers, one for header and one for content, we allow all above functions from trackerlogic to
       write to a fixed location, leaving SUCCESS_HTTP_HEADER_LENGTH bytes in our static buffer, which is enough for the static string
       plus dynamic space needed to expand our Content-Length value. We reserve SUCCESS_HTTP_SIZE_OFF for it expansion and calculate
       the space NOT needed to expand in reply_off
    */
    size_t reply_off = SUCCESS_HTTP_SIZE_OFF - snprintf( static_reply, 0, "%zd", reply_size );

    /* 2. Now we sprintf our header so that sprintf writes its terminating '\0' exactly one byte before content starts. Complete
       packet size is increased by size of header plus one byte '\n', we  will copy over '\0' in next step */
    reply_size += 1 + sprintf( static_reply + reply_off, "HTTP/1.0 200 OK\r\nContent-Type: text/plain\r\nContent-Length: %zd\r\n\r", reply_size );

    /* 3. Finally we join both blocks neatly */
    static_reply[ SUCCESS_HTTP_HEADER_LENGTH - 1 ] = '\n';

    senddata( s, h, static_reply + reply_off, reply_size );
  } else {
    if( h ) array_reset(&h->r);
    free( h ); io_close( s );
  }
}

void graceful( int s ) {
  if( s == SIGINT ) {
    signal( SIGINT, SIG_IGN);
    deinit_logic();
    exit( 0 );
  }
}

void usage( char *name ) {
  fprintf( stderr, "Usage: %s [-i serverip] [-p serverport] [-d serverdirectory]"
#ifdef WANT_CLOSED_TRACKER
  " [-oc]"
#endif
#ifdef WANT_BLACKLIST
  " [-bB]"
#endif
  "\n", name );
}

void help( char *name ) {
  usage( name );
  fprintf( stderr, "\t-i serverip\tspecify ip to bind to (default: *)\n"
                   "\t-p serverport\tspecify port to bind to (default: 6969)\n"
                   "\t-d serverdir\tspecify directory containing white- or black listed torrent info_hashes (default: \".\")\n"
#ifdef WANT_CLOSED_TRACKER
                   "\t-o\t\tmake tracker an open tracker, e.g. do not check for white list (default: off)\n"
                   "\t-c\t\tmake tracker a closed tracker, e.g. check each announced torrent against white list (default: on)\n"
#endif
#ifdef WANT_BLACKLIST
                   "\t-b\t\tmake tracker check its black list, e.g. check each announced torrent against black list (default: on)\n"
                   "\t-B\t\tmake tracker check its black list, e.g. check each announced torrent against black list (default: off)\n"
#endif
#ifdef WANT_CLOSED_TRACKER
                   "\n* To white list a torrent, touch a file inside serverdir with info_hash hex string.\n"
#endif
#ifdef WANT_BLACKLIST
#ifndef WANT_CLOSED_TRACKER
                   "\n"
#endif
                   "* To white list a torrent, touch a file inside serverdir with info_hash hex string, preprended by '-'.\n"
#endif
);
}

int main( int argc, char **argv ) {
  int s=socket_tcp4();
  tai6464 t, next_timeout_check;
  char *serverip = NULL;
  char *serverdir = ".";
  uint16 port = 6969;
  unsigned char ip[4];

  while( 1 ) {
    switch( getopt(argc,argv,":i:p:d:ocbBh") ) {
      case -1: goto allparsed;
      case 'i': serverip = optarg; break;
      case 'p': port = (uint16)atol( optarg ); break;
      case 'd': serverdir = optarg; break;
      case 'h': help( argv[0]); exit(0);
#ifdef WANT_CLOSED_TRACKER
      case 'o': g_closedtracker = 0; break;
      case 'c': g_closedtracker = 1; break;
#endif
#ifdef WANT_BLACKLIST
      case 'b': g_check_blacklist = 1; break;
      case 'B': g_check_blacklist = 0; break;
#endif
      default:
      case '?': usage( argv[0] ); exit(1);
    }
  }

allparsed:
  if (socket_bind4_reuse(s,serverip,port)==-1)
    panic("socket_bind4_reuse");

  setegid((gid_t)-2); setuid((uid_t)-2);
  setgid((gid_t)-2); seteuid((uid_t)-2);

  if (socket_listen(s,16)==-1)
    panic("socket_listen");

  if (!io_fd(s))
    panic("io_fd");

  signal( SIGPIPE, SIG_IGN );
  signal( SIGINT, graceful );
  if( init_logic( serverdir ) == -1 )
    panic("Logic not started");

  ot_start_time = time( NULL );

  io_wantread( s );
  taia_now( &next_timeout_check );
  taia_addsec( &next_timeout_check, &next_timeout_check, OT_CLIENT_TIMEOUT_CHECKINTERVAL );

  for (;;) {
    int64 i;
    taia_now(&t);
    taia_addsec(&t,&t,OT_CLIENT_TIMEOUT_CHECKINTERVAL);
    io_waituntil(t);

    taia_now(&t);
    if( taia_less( &next_timeout_check, &t ) ) {
      while( ( i = io_timeouted() ) != -1 ) {
        struct http_data* h=io_getcookie(i);
        if( h ) {
          array_reset( &h->r );
          free( h );
        }
        io_close(i);
      }
      taia_now(&next_timeout_check);
      taia_addsec(&next_timeout_check,&next_timeout_check,OT_CLIENT_TIMEOUT_CHECKINTERVAL);
    }

    while( ( i = io_canread() ) != -1 ) {
      if( i == s ) {
        int n;
        while( ( n = socket_accept4( s, (char*)ip, &port) ) != -1 ) {
          if( io_fd( n ) ) {
            struct http_data* h=(struct http_data*)malloc(sizeof(struct http_data));
            io_wantread(n);

            if (h) {
              byte_zero(h,sizeof(struct http_data));
              memmove(h->ip,ip,sizeof(ip));
              taia_now(&t);
              taia_addsec(&t,&t,OT_CLIENT_TIMEOUT);
              io_timeout(n,t);
              io_setcookie(n,h);
              ++ot_overall_connections;
            } else
              io_close(n);
          } else
            io_close(n);
        }
        if( errno==EAGAIN )
          io_eagain(s);
        else
          carp("socket_accept4");
      } else {
        /* unsigned (sic!) */ char buf[8192];
        struct http_data* h=io_getcookie(i);

        int l=io_tryread(i,buf,sizeof buf);
        if( l <= 0 ) {
          if( h ) {
            array_reset(&h->r);
            free(h);
          }
          io_close(i);
        } else {
          array_catb(&h->r,buf,l);

          if( array_failed(&h->r))
            httperror(i,h,"500 Server Error","Request too long.");
          else if (array_bytes(&h->r)>8192)
            httperror(i,h,"500 request too long","You sent too much headers");
          else if ((l=header_complete(h)))
            httpresponse(i,h);
          else {
            taia_now(&t);
            taia_addsec(&t,&t,OT_CLIENT_TIMEOUT);
            io_timeout(i,t);
          }
        }
      }
    }
  }
  return 0;
}