sockfilt.c

THIS IS HTTP CURL Example

/***************************************************************************
 *                                  _   _ ____  _
 *  Project                     ___| | | |  _ \| |
 *                             / __| | | | |_) | |
 *                            | (__| |_| |  _ <| |___
 *                             \___|\___/|_| \_\_____|
 *
 * Copyright (C) 1998 - 2007, Daniel Stenberg, <[e-mail]>, 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: sockfilt.c,v 1.38 2007-10-09 23:21:29 yangtse Exp $
 ***************************************************************************/

/* Purpose
 *
 * 1. Accept a TCP connection on a custom port (ipv4 or ipv6), or connect
 *    to a given (localhost) port.
 *
 * 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

#define ENABLE_CURLX_PRINTF
/* make the curlx header define all printf() functions to use the curlx_*
   versions instead */
#include "curlx.h" /* from the private lib dir */
#include "getpart.h"
#include "inet_pton.h"
#include "util.h"

/* 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

const char *serverlogfile = (char *)DEFAULT_LOGFILE;

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

  for(i=0; i<len; i++) {
    switch(ptr[i]) {
    case '\n':
      sprintf(optr, "\\n");
      width += 2;
      optr += 2;
      break;
    case '\r':
      sprintf(optr, "\\r");
      width += 2;
      optr += 2;
      break;
    default:
      sprintf(optr, "%c", (ISGRAPH(ptr[i]) || ptr[i]==0x20) ?ptr[i]:'.');
      width++;
      optr++;
      break;
    }

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

#ifdef SIGPIPE
static void sigpipe_handler(int sig)
{
  (void)sig; /* prevent warning */
  sigpipe = 1;
}
#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 */
  ACTIVE_DISCONNECT  /* as a client, disconnected from 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 sockfd;
  curl_socket_t maxfd;
  ssize_t rc;
  ssize_t nread_stdin;
  ssize_t nread_socket;
  ssize_t bytes_written;
  ssize_t buffer_len;

 /* 'buffer' is this excessively large only to be able to support things like
    test 1003 which tests exceedingly large server response lines */
  unsigned char buffer[17010];
  char data[16];

  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;
    /* there's always a socket to wait for */
    FD_SET(sockfd, &fds_read);
    maxfd = sockfd;
    break;

  case PASSIVE_CONNECT:

    sockfd = *sockfdp;
    if(CURL_SOCKET_BAD == sockfd) {
      /* eeek, we are supposedly connected and then this cannot be -1 ! */
      logmsg("socket is -1! on %s:%d", __FILE__, __LINE__);
      maxfd = 0; /* stdin */
    }
    else {
      /* 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(CURL_SOCKET_BAD != sockfd) {
      FD_SET(sockfd, &fds_read);
      maxfd = sockfd;
    }
    else {
      logmsg("No socket to read on");
      maxfd = 0;
    }
    break;

  case ACTIVE_DISCONNECT:

    logmsg("disconnected, no socket to read on");
    maxfd = 0;
    sockfd = CURL_SOCKET_BAD;
    break;

  } /* switch(*mode) */

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

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

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


  if(FD_ISSET(fileno(stdin), &fds_read)) {
    /* 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_stdin = read(fileno(stdin), buffer, 5);
    if(5 == nread_stdin) {

      logmsg("Received %c%c%c%c (on stdin)",
             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 to PORT with "IPv[num]/[port]" */
        sprintf((char *)buffer, "IPv%d/%d\n", use_ipv6?6:4, (int)port);
        buffer_len = (ssize_t)strlen((char *)buffer);
        snprintf(data, sizeof(data), "PORT\n%04x\n", buffer_len);
        write(fileno(stdout), data, 10);
        write(fileno(stdout), buffer, buffer_len);
      }
      else if(!memcmp("QUIT", buffer, 4)) {
        /* just die */
        logmsg("quits");
        return FALSE;
      }
      else if(!memcmp("DATA", buffer, 4)) {
        /* data IN => data OUT */

        if(5 != read(fileno(stdin), buffer, 5))
          return FALSE;
        buffer[5] = '\0';

        buffer_len = (ssize_t)strtol((char *)buffer, NULL, 16);
        if (buffer_len > (ssize_t)sizeof(buffer)) {
          logmsg("Buffer size %d too small for data size %d", 
                   (int)sizeof(buffer), buffer_len);
          return FALSE;
        }
        logmsg("> %d bytes data, server => client", buffer_len);

        if(buffer_len > (ssize_t)sizeof(buffer)) {
          logmsg("ERROR: %d bytes of data does not fit within the %d "
                 "bytes buffer", buffer_len, sizeof(buffer));
          return FALSE;
        }

        /*
         * To properly support huge data chunks, we need to repeat the call
         * to read() until we're done or it fails.
         */
        nread_stdin = 0;
        do {
          /* get data in the buffer at the correct position */
          rc = read(fileno(stdin), &buffer[nread_stdin],
                    buffer_len - nread_stdin);
          logmsg("read %d bytes", rc);
          if(rc <= 0)
            return FALSE;
          nread_stdin += rc;
        } while (nread_stdin < buffer_len);

        lograw(buffer, buffer_len);

        if(*mode == PASSIVE_LISTEN) {
          logmsg("*** We are disconnected!");
          write(fileno(stdout), "DISC\n", 5);
        }
        else {
          /* send away on the socket */
          bytes_written = swrite(sockfd, buffer, buffer_len);
          if(bytes_written != buffer_len) {
            logmsg("Not all data was sent. Bytes to send: %d sent: %d", 
                   buffer_len, bytes_written);
          }
        }
      }
      else if(!memcmp("DISC", buffer, 4)) {
        /* disconnect! */
        write(fileno(stdout), "DISC\n", 5);