sockfilt.c

/***************************************************************************
 *                                  _   _ ____  _
 *  Project                     ___| | | |  _ \| |
 *                             / __| | | | |_) | |
 *                            | (__| |_| |  _ <| |___
 *                             \___|\___/|_| \_\_____|
 *
 * Copyright (C) 1998 - 2005, Daniel Stenberg, <daniel@haxx.se>, et al.
 *
 * This software is licensed as described in the file COPYING, which
 * you should have received as part of this distribution. The terms
 * are also available at http://curl.haxx.se/docs/copyright.html.
 *
 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
 * copies of the Software, and permit persons to whom the Software is
 * furnished to do so, under the terms of the COPYING file.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 * $Id$
 ***************************************************************************/

/* Purpose
 *
 * 1. Accept a TCP connection on a custom port (ipv4 or ipv6).
 *
 * 2. Get commands on STDIN. Pass data on to the TCP stream.
 *    Get data from TCP stream and pass on to STDOUT.
 *
 * This program is made to perform all the socket/stream/connection stuff for
 * the test suite's (perl) FTP server. Previously the perl code did all of
 * this by its own, but I decided to let this program do the socket layer
 * because of several things:
 *
 * o We want the perl code to work with rather old perl installations, thus
 *   we cannot use recent perl modules or features.
 *
 * o We want IPv6 support for systems that provide it, and doing optional IPv6
 *   support in perl seems if not impossible so at least awkward.
 *
 * o We want FTP-SSL support, which means that a connection that starts with
 *   plain sockets needs to be able to "go SSL" in the midst. This would also
 *   require some nasty perl stuff I'd rather avoid.
 *
 * (Source originally based on sws.c)
 */
#include "setup.h" /* portability help from the lib directory */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
#include <signal.h>
#include <time.h>
#include <ctype.h>
#include <sys/time.h>
#include <sys/types.h>

#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#ifdef HAVE_SYS_SOCKET_H
#include <sys/socket.h>
#endif
#ifdef HAVE_NETINET_IN_H
#include <netinet/in.h>
#endif
#ifdef _XOPEN_SOURCE_EXTENDED
/* This define is "almost" required to build on HPUX 11 */
#include <arpa/inet.h>
#endif
#ifdef HAVE_NETDB_H
#include <netdb.h>
#endif

#include "curlx.h" /* from the private lib dir */
#include "getpart.h"
#include "inet_pton.h"

#ifndef FALSE
#define FALSE 0
#endif
#ifndef TRUE
#define TRUE 1
#endif

#if defined(WIN32) && !defined(__CYGWIN__)
#include <windows.h>
#include <winsock2.h>
#include <process.h>

#define sleep(sec)   Sleep ((sec)*1000)

#define EINPROGRESS  WSAEINPROGRESS
#define EWOULDBLOCK  WSAEWOULDBLOCK
#define EISCONN      WSAEISCONN
#define ENOTSOCK     WSAENOTSOCK
#define ECONNREFUSED WSAECONNREFUSED

static void win32_cleanup(void);

#if defined(ENABLE_IPV6) && defined(__MINGW32__)
const struct in6_addr in6addr_any = {{ IN6ADDR_ANY_INIT }};
#endif
#endif

/* include memdebug.h last */
#include "memdebug.h"

#define DEFAULT_PORT 8999

#ifndef DEFAULT_LOGFILE
#define DEFAULT_LOGFILE "log/sockfilt.log"
#endif

#ifdef SIGPIPE
static volatile int sigpipe;  /* Why? It's not used */
#endif

char *socklogfile = (char *)DEFAULT_LOGFILE;

/*
 * ourerrno() returns the errno (or equivalent) on this platform to
 * hide platform specific for the function that calls this.
 */
static int ourerrno(void)
{
#ifdef WIN32
  return (int)GetLastError();
#else
  return errno;
#endif
}

static void logmsg(const char *msg, ...)
{
  time_t t = time(NULL);
  va_list ap;
  struct tm *curr_time = localtime(&t);
  char buffer[256]; /* possible overflow if you pass in a huge string */
  FILE *logfp;

  va_start(ap, msg);
  vsprintf(buffer, msg, ap);
  va_end(ap);

  logfp = fopen(socklogfile, "a");

  fprintf(logfp?logfp:stderr, /* write to stderr if the logfile doesn't open */
          "%02d:%02d:%02d %s\n",
          curr_time->tm_hour,
          curr_time->tm_min,
          curr_time->tm_sec, buffer);
  if(logfp)
    fclose(logfp);
}

static void lograw(unsigned char *buffer, int len)
{
  char data[120];
  int i;
  unsigned char *ptr = buffer;
  char *optr = data;
  int width=0;

  for(i=0; i<len; i++) {
    sprintf(optr, "%c",
            (isgraph(ptr[i]) || ptr[i]==0x20) ?ptr[i]:'.');
    optr += 1;
    width += 1;

    if(width>60) {
      logmsg("RAW: '%s'", data);
      width = 0;
      optr = data;
    }
  }
  if(width)
    logmsg("RAW: '%s'", data);
}

#ifdef SIGPIPE
static void sigpipe_handler(int sig)
{
  (void)sig; /* prevent warning */
  sigpipe = 1;
}
#endif

#if defined(WIN32) && !defined(__CYGWIN__)
#undef perror
#define perror(m) win32_perror(m)

static void win32_perror(const char *msg)
{
  char buf[256];
  DWORD err = WSAGetLastError();

  if (!FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM, NULL, err,
                     LANG_NEUTRAL, buf, sizeof(buf), NULL))
     snprintf(buf, sizeof(buf), "Unknown error %lu (%#lx)", err, err);
  if (msg)
     fprintf(stderr, "%s: ", msg);
  fprintf(stderr, "%s\n", buf);
}
#endif

#if defined(WIN32) && !defined(__CYGWIN__)
static void win32_init(void)
{
  WORD wVersionRequested;
  WSADATA wsaData;
  int err;
  wVersionRequested = MAKEWORD(2, 0);

  err = WSAStartup(wVersionRequested, &wsaData);

  if (err != 0) {
    perror("Winsock init failed");
    logmsg("Error initialising winsock -- aborting\n");
    exit(1);
  }

  if ( LOBYTE( wsaData.wVersion ) != 2 ||
       HIBYTE( wsaData.wVersion ) != 0 ) {

    WSACleanup();
    perror("Winsock init failed");
    logmsg("No suitable winsock.dll found -- aborting\n");
    exit(1);
  }
}
static void win32_cleanup(void)
{
  WSACleanup();
}
#endif

char use_ipv6=FALSE;
unsigned short port = DEFAULT_PORT;
unsigned short connectport = 0; /* if non-zero, we activate this mode */

enum sockmode {
  PASSIVE_LISTEN, /* as a server waiting for connections */
  PASSIVE_CONNECT, /* as a server, connected to a client */
  ACTIVE    /* as a client, connected to a server */
};

/*
  sockfdp is a pointer to an established stream or CURL_SOCKET_BAD

  if sockfd is CURL_SOCKET_BAD, listendfd is a listening socket we must
  accept()
*/
static int juggle(curl_socket_t *sockfdp,
                  curl_socket_t listenfd,
                  enum sockmode *mode)
{
  struct timeval timeout;
  fd_set fds_read;
  fd_set fds_write;
  fd_set fds_err;
  curl_socket_t maxfd;
  int r;
  unsigned char buffer[256]; /* FIX: bigger buffer */
  char data[256];
  int sockfd;

  timeout.tv_sec = 120;
  timeout.tv_usec = 0;

  FD_ZERO(&fds_read);
  FD_ZERO(&fds_write);
  FD_ZERO(&fds_err);

  FD_SET(fileno(stdin), &fds_read);

  switch(*mode) {
  case PASSIVE_LISTEN:
    /* server mode */
    sockfd = listenfd;
    logmsg("waiting for a client to connect on socket %d", (int)sockfd);
    /* there's always a socket to wait for */
    FD_SET(sockfd, &fds_read);
    maxfd = sockfd;
    break;

  case PASSIVE_CONNECT:
    sockfd = *sockfdp;
    logmsg("waiting for data from client on socket %d", (int)sockfd);
    /* there's always a socket to wait for */
    FD_SET(sockfd, &fds_read);
    maxfd = sockfd;
    break;

  case ACTIVE:
    sockfd = *sockfdp;

    /* sockfd turns CURL_SOCKET_BAD when our connection has been closed */
    if(sockfd != CURL_SOCKET_BAD) {
      FD_SET(sockfd, &fds_read);
      maxfd = sockfd;
      logmsg("waiting for data from client on socket %d", (int)sockfd);
    }
    else {
      logmsg("No socket to read on");
      maxfd = 0;
    }
    break;
  }

  do {
    r = select(maxfd + 1, &fds_read, &fds_write, &fds_err, &timeout);
  } while((r == -1) && (ourerrno() == EINTR));

  logmsg("select() returned %d", r);

  switch(r) {
  case -1:
    return FALSE;

  case 0: /* timeout! */
    return TRUE;
  }


  if(FD_ISSET(fileno(stdin), &fds_read)) {
    size_t nread;
    logmsg("data on stdin");
    /* read from stdin, commands/data to be dealt with and possibly passed on
       to the socket

       protocol:

       4 letter command + LF [mandatory]

       4-digit hexadecimal data length + LF [if the command takes data]
       data                       [the data being as long as set above]

       Commands:

       DATA - plain pass-thru data
    */
    nread = read(fileno(stdin), buffer, 5);
    if(5 == nread) {

      logmsg("Received command %c%c%c%c",
             buffer[0], buffer[1], buffer[2], buffer[3] );

      if(!memcmp("PING", buffer, 4)) {
        /* send reply on stdout, just proving we are alive */
        write(fileno(stdout), "PONG\n", 5);
      }

      else if(!memcmp("PORT", buffer, 4)) {
        /* question asking us what PORT number we are listening to.
           Replies with PORT with "IPv[num]/[port]" */
        sprintf((char *)buffer, "IPv%d/%d\n", use_ipv6?6:4, port);
        r = strlen((char *)buffer);
        sprintf(data, "PORT\n%04x\n", r);
        write(fileno(stdout), data, 10);
        write(fileno(stdout), buffer, r);
      }
      else if(!memcmp("QUIT", buffer, 4)) {
        /* just die */
        logmsg("quits");
        exit(0);
      }
      else if(!memcmp("DATA", buffer, 4)) {
        /* data IN => data OUT */
        long len;

        if(5 != read(fileno(stdin), buffer, 5))
          return FALSE;

        len = strtol((char *)buffer, NULL, 16);
        if(len != read(fileno(stdin), buffer, len))
          return FALSE;

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

        if(*mode == PASSIVE_LISTEN) {
          logmsg(".., but we are disconnected!");
          write(fileno(stdout), "DISC\n", 5);
        }
        else
          /* send away on the socket */
          swrite(sockfd, buffer, len);
      }
      else if(!memcmp("DISC", buffer, 4)) {
        /* disconnect! */
        write(fileno(stdout), "DISC\n", 5);
        if(sockfd != CURL_SOCKET_BAD) {
          logmsg("====> Client forcibly disconnected");
          sclose(sockfd);
          *sockfdp = CURL_SOCKET_BAD;
        }
        else
          logmsg("attempt to close already dead connection");
        return TRUE;
      }
    }
    else {
      logmsg("read %d from stdin, exiting", (int)nread);
      exit(0);
    }
  }

  if((sockfd != CURL_SOCKET_BAD) && (FD_ISSET(sockfd, &fds_read)) ) {
    logmsg("data on socket");

    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(-1 == sockfd)
        logmsg("accept() failed\n");
      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 */
    r = sread(sockfd, buffer, sizeof(buffer));

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

    sprintf(data, "DATA\n%04x\n", r);
    write(fileno(stdout), data, 10);
    write(fileno(stdout), buffer, r);

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

  return TRUE;
}

int main(int argc, char *argv[])
{
  struct sockaddr_in me;
#ifdef ENABLE_IPV6
  struct sockaddr_in6 me6;
#endif /* ENABLE_IPV6 */
  int sock;
  int msgsock = CURL_SOCKET_BAD; /* no stream socket yet */
  int flag;
  FILE *pidfile;
  char *pidname= (char *)".sockfilt.pid";
  int rc;
  int arg=1;
  bool ok = FALSE;
  enum sockmode mode = PASSIVE_LISTEN; /* default */

  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)
        socklogfile = 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 {
      puts("Usage: sockfilt [option]\n"
           " --version\n"
           " --logfile [file]\n"
           " --pidfile [file]\n"
           " --ipv4\n"
           " --ipv6\n"
           " --port [port]");
      exit(0);
    }
  }

#if defined(WIN32) && !defined(__GNUC__) || defined(__MINGW32__)
  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

#ifdef ENABLE_IPV6
  if(!use_ipv6)
#endif
    sock = socket(AF_INET, SOCK_STREAM, 0);
#ifdef ENABLE_IPV6
  else
    sock = socket(AF_INET6, SOCK_STREAM, 0);
#endif

  if (sock < 0) {
    perror("opening stream socket");
    logmsg("Error opening socket");
    exit(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;
      Curl_inet_pton(AF_INET, "127.0.0.1", &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);
      Curl_inet_pton(AF_INET, "::1", &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);
      exit(1);
    }
    logmsg("====> Client connect");
    msgsock = sock; /* use this as stream */
  }
  else {
    /* passive daemon style */

    flag = 1;
    if (setsockopt
        (sock, SOL_SOCKET, SO_REUSEADDR, (const void *) &flag,
         sizeof(int)) < 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(port);
      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(port);
      rc = bind(sock, (struct sockaddr *) &me6, sizeof(me6));
    }
#endif /* ENABLE_IPV6 */
    if(rc < 0) {
      perror("binding stream socket");
      logmsg("Error binding socket");
      exit(1);
    }

    if(!port) {
      /* 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) {
        fprintf(stderr, "getsockname() failed");
        return 1;
      }
      port = ntohs(add.sin_port);
    }

    /* start accepting connections */
    listen(sock, 0);

  }

  pidfile = fopen(pidname, "w");
  if(pidfile) {
    fprintf(pidfile, "%d\n", (int)getpid());
    fclose(pidfile);
  }
  else
    fprintf(stderr, "Couldn't write pid file\n");

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

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

  do {
    ok = juggle(&msgsock, sock, &mode);
  } while(ok);

  sclose(sock);

  return 0;
}