sockfilt.c

THIS IS HTTP CURL Example

        if(sockfd != CURL_SOCKET_BAD) {
          logmsg("====> Client forcibly disconnected");
          sclose(sockfd);
          *sockfdp = CURL_SOCKET_BAD;
          if(*mode == PASSIVE_CONNECT)
            *mode = PASSIVE_LISTEN;
          else
            *mode = ACTIVE_DISCONNECT;
        }
        else
          logmsg("attempt to close already dead connection");
        return TRUE;
      }
    }
    else if(-1 == nread_stdin) {
      logmsg("read %d from stdin, exiting", nread_stdin);
      return FALSE;
    }
  }


  if((sockfd != CURL_SOCKET_BAD) && (FD_ISSET(sockfd, &fds_read)) ) {

    if(*mode == PASSIVE_LISTEN) {
      /* there's no stream set up yet, this is an indication that there's a
         client connecting. */
      sockfd = accept(sockfd, NULL, NULL);
      if(CURL_SOCKET_BAD == sockfd)
        logmsg("accept() failed");
      else {
        logmsg("====> Client connect");
        write(fileno(stdout), "CNCT\n", 5);
        *sockfdp = sockfd; /* store the new socket */
        *mode = PASSIVE_CONNECT; /* we have connected */
      }
      return TRUE;
    }

    /* read from socket, pass on data to stdout */
    nread_socket = sread(sockfd, buffer, sizeof(buffer));

    if(nread_socket <= 0) {
      logmsg("====> Client disconnect");
      write(fileno(stdout), "DISC\n", 5);
      sclose(sockfd);
      *sockfdp = CURL_SOCKET_BAD;
      if(*mode == PASSIVE_CONNECT)
        *mode = PASSIVE_LISTEN;
      else
        *mode = ACTIVE_DISCONNECT;
      return TRUE;
    }

    snprintf(data, sizeof(data), "DATA\n%04x\n", nread_socket);
    write(fileno(stdout), data, 10);
    write(fileno(stdout), buffer, nread_socket);

    logmsg("< %d bytes data, client => server", nread_socket);
    lograw(buffer, nread_socket);
  }

  return TRUE;
}

static curl_socket_t sockdaemon(curl_socket_t sock,
                                unsigned short *listenport)
{
  /* passive daemon style */
  struct sockaddr_in me;
#ifdef ENABLE_IPV6
  struct sockaddr_in6 me6;
#endif /* ENABLE_IPV6 */
  int flag = 1;
  int rc;
  int maxretr = 12;
  int delay= 10;

  rc = setsockopt(sock, SOL_SOCKET, SO_REUSEADDR,
       (void *)&flag, sizeof(flag));
  while ((rc < 0) && maxretr) {
    maxretr--;
    go_sleep(delay);
    delay *= 2; /* double the sleep for next attempt */
    rc = setsockopt(sock, SOL_SOCKET, SO_REUSEADDR,
         (void *)&flag, sizeof(flag));
  }
  if (rc < 0) {
    perror("setsockopt(SO_REUSEADDR)");
  }

#ifdef ENABLE_IPV6
  if(!use_ipv6) {
#endif
    me.sin_family = AF_INET;
    me.sin_addr.s_addr = INADDR_ANY;
    me.sin_port = htons(*listenport);
    rc = bind(sock, (struct sockaddr *) &me, sizeof(me));
#ifdef ENABLE_IPV6
  }
  else {
    memset(&me6, 0, sizeof(struct sockaddr_in6));
    me6.sin6_family = AF_INET6;
    me6.sin6_addr = in6addr_any;
    me6.sin6_port = htons(*listenport);
    rc = bind(sock, (struct sockaddr *) &me6, sizeof(me6));
  }
#endif /* ENABLE_IPV6 */
  if(rc < 0) {
    perror("binding stream socket");
    logmsg("Error binding socket");
    return CURL_SOCKET_BAD;
  }

  if(!*listenport) {
    /* The system picked a port number, now figure out which port we actually
       got */
    /* we succeeded to bind */
    struct sockaddr_in add;
    socklen_t socksize = sizeof(add);

    if(getsockname(sock, (struct sockaddr *) &add,
                   &socksize)<0) {
      logmsg("getsockname() failed with error: %d", SOCKERRNO);
      return CURL_SOCKET_BAD;
    }
    *listenport = ntohs(add.sin_port);
  }

  /* start accepting connections */
  rc = listen(sock, 4);
  if(0 != rc) {
    logmsg("listen() failed with error: %d", SOCKERRNO);
    sclose(sock);
    return CURL_SOCKET_BAD;
  }

  return sock;
}

static curl_socket_t mksock(bool ipv6)
{
  curl_socket_t sock;
#ifdef ENABLE_IPV6
  if(!ipv6)
#else
    (void)ipv6;
#endif
  sock = socket(AF_INET, SOCK_STREAM, 0);
#ifdef ENABLE_IPV6
  else
    sock = socket(AF_INET6, SOCK_STREAM, 0);
#endif

  if (CURL_SOCKET_BAD == sock) {
    perror("opening stream socket");
    logmsg("Error opening socket");
  }

  return sock;
}


int main(int argc, char *argv[])
{
  struct sockaddr_in me;
#ifdef ENABLE_IPV6
  struct sockaddr_in6 me6;
#endif /* ENABLE_IPV6 */
  curl_socket_t sock;
  curl_socket_t msgsock;
  FILE *pidfile;
  char *pidname= (char *)".sockfilt.pid";
  int rc;
  int error;
  int arg=1;
  enum sockmode mode = PASSIVE_LISTEN; /* default */
  const char *addr = NULL;

  while(argc>arg) {
    if(!strcmp("--version", argv[arg])) {
      printf("sockfilt IPv4%s\n",
#ifdef ENABLE_IPV6
             "/IPv6"
#else
             ""
#endif
             );
      return 0;
    }
    else if(!strcmp("--pidfile", argv[arg])) {
      arg++;
      if(argc>arg)
        pidname = argv[arg++];
    }
    else if(!strcmp("--logfile", argv[arg])) {
      arg++;
      if(argc>arg)
        serverlogfile = argv[arg++];
    }
    else if(!strcmp("--ipv6", argv[arg])) {
#ifdef ENABLE_IPV6
      use_ipv6=TRUE;
#endif
      arg++;
    }
    else if(!strcmp("--ipv4", argv[arg])) {
      /* for completeness, we support this option as well */
      use_ipv6=FALSE;
      arg++;
    }
    else if(!strcmp("--port", argv[arg])) {
      arg++;
      if(argc>arg) {
        port = (unsigned short)atoi(argv[arg]);
        arg++;
      }
    }
    else if(!strcmp("--connect", argv[arg])) {
      /* Asked to actively connect to the specified local port instead of
         doing a passive server-style listening. */
      arg++;
      if(argc>arg) {
        connectport = (unsigned short)atoi(argv[arg]);
        arg++;
      }
    }
    else if(!strcmp("--addr", argv[arg])) {
      /* Set an IP address to use with --connect; otherwise use localhost */
      arg++;
      if(argc>arg) {
        addr = argv[arg];
        arg++;
      }
    }
    else {
      puts("Usage: sockfilt [option]\n"
           " --version\n"
           " --logfile [file]\n"
           " --pidfile [file]\n"
           " --ipv4\n"
           " --ipv6\n"
           " --port [port]\n"
           " --connect [port]\n"
           " --addr [address]");
      return 0;
    }
  }

#ifdef WIN32
  win32_init();
  atexit(win32_cleanup);
#else

#ifdef SIGPIPE
#ifdef HAVE_SIGNAL
  signal(SIGPIPE, sigpipe_handler);
#endif
#ifdef HAVE_SIGINTERRUPT
  siginterrupt(SIGPIPE, 1);
#endif
#endif
#endif


  sock = mksock(use_ipv6);
  if (CURL_SOCKET_BAD == sock) {
    logmsg("Error opening socket: %d", SOCKERRNO);
    return 1;
  }

  if(connectport) {
    /* Active mode, we should connect to the given port number */
    mode = ACTIVE;
#ifdef ENABLE_IPV6
    if(!use_ipv6) {
#endif
      memset(&me, 0, sizeof(me));
      me.sin_family = AF_INET;
      me.sin_port = htons(connectport);
      me.sin_addr.s_addr = INADDR_ANY;
      if (!addr)
        addr = "127.0.0.1";
      Curl_inet_pton(AF_INET, addr, &me.sin_addr);

      rc = connect(sock, (struct sockaddr *) &me, sizeof(me));
#ifdef ENABLE_IPV6
    }
    else {
      memset(&me6, 0, sizeof(me6));
      me6.sin6_family = AF_INET6;
      me6.sin6_port = htons(connectport);
      if (!addr)
        addr = "::1";
      Curl_inet_pton(AF_INET6, addr, &me6.sin6_addr);

      rc = connect(sock, (struct sockaddr *) &me6, sizeof(me6));
    }
#endif /* ENABLE_IPV6 */
    if(rc) {
      perror("connecting stream socket");
      logmsg("Error connecting to port %d", port);
      sclose(sock);
      return 1;
    }
    logmsg("====> Client connect");
    msgsock = sock; /* use this as stream */
  }
  else {
    /* passive daemon style */
    sock = sockdaemon(sock, &port);
    if(CURL_SOCKET_BAD == sock)
      return 1;
    msgsock = CURL_SOCKET_BAD; /* no stream socket yet */
  }

  logmsg("Running IPv%d version",
         (use_ipv6?6:4));

  if(connectport)
    logmsg("Connected to port %d", connectport);
  else
    logmsg("Listening on port %d", port);

  pidfile = fopen(pidname, "w");
  if(pidfile) {
    int pid = (int)getpid();
    fprintf(pidfile, "%d\n", pid);
    fclose(pidfile);
    logmsg("Wrote pid %d to %s", pid, pidname);
  }
  else {
    error = ERRNO;
    logmsg("fopen() failed with error: %d %s", error, strerror(error));
    logmsg("Error opening file: %s", pidname);
    logmsg("Couldn't write pid file");
    sclose(sock);
    return 1;
  }

  while(juggle(&msgsock, sock, &mode));

  sclose(sock);

  return 0;
}