htc.c

穿越防火墙技术代码

/*
htc.c

Copyright (C) 1999 Lars Brinkhoff.  See COPYING for terms and conditions.

htc is the client half of httptunnel.  httptunnel creates a virtual
two-way data path tunneled in HTTP requests.
*/

#include <stdio.h>
#include <stdlib.h>
#include <unistd_.h>
#include <signal.h>
#include <sys/poll_.h>
#include <sys/time.h>
#include <sys/stat.h>

#include "common.h"
#include "base64.h"

#define DEFAULT_PROXY_PORT 8080
#define DEFAULT_PROXY_BUFFER_TIMEOUT 500 /* milliseconds */

typedef struct
{
  char *me;
  char *device;
  char *host_name;
  int host_port;
  char *proxy_name;
  int proxy_port;
  size_t proxy_buffer_size;
  int proxy_buffer_timeout;
  size_t content_length;
  int forward_port;
  int strict_content_length;
  int keep_alive;
  int max_connection_age;
  char *proxy_authorization;
  char *user_agent;
} Arguments;

#define NO_PROXY_BUFFER 0
#define NO_PROXY (NULL)

int debug_level = 0;
FILE *debug_file = NULL;

static void
usage (FILE *f, const char *me)
{
  fprintf (f,
"Usage: %s [OPTION]... HOST[:PORT]\n"
"Set up a httptunnel connection to PORT at HOST (default port is %d).\n"
"When a connection is made, I/O is redirected from the source specified\n"
"by the --device or --forward-port switch to the tunnel.\n"
"\n"
"  -A, --proxy-authorization USER:PASSWORD  proxy authorization\n"
"  --proxy-authorization-file FILE          proxy authorization file\n"
"  -B, --proxy-buffer-size BYTES  assume a proxy buffer size of BYTES bytes\n"
"                                 (k, M, and G postfixes recognized)\n"
"  -c, --content-length BYTES     use HTTP PUT requests of BYTES size\n"
"                                 (k, M, and G postfixes recognized)\n"
"  -d, --device DEVICE            use DEVICE for input and output\n"
#ifdef DEBUG_MODE
"  -D, --debug [LEVEL]            enable debugging mode\n"
#endif
"  -F, --forward-port PORT        use TCP port PORT for input and output\n"
"  -h, --help                     display this help and exit\n"
"  -k, --keep-alive SECONDS       send keepalive bytes every SECONDS seconds\n"
"                                 (default is %d)\n"
#ifdef DEBUG_MODE
"  -l, --logfile FILE             specify file for debugging output\n"
#endif
"  -M, --max-connection-age SEC   maximum time a connection will stay\n"
"                                 open is SEC seconds (default is %d)\n"
"  -P, --proxy HOSTNAME[:PORT]    use a HTTP proxy (default port is %d)\n"
"  -S, --strict-content-length    always write Content-Length bytes in requests\n"
"  -T, --timeout TIME             timeout, in milliseconds, before sending\n"
"                                 padding to a buffering proxy\n"
"  -U, --user-agent STRING        specify User-Agent value in HTTP requests\n"
"  -V, --version                  output version information and exit\n"
"\n"
"Report bugs to %s.\n",
	   me, DEFAULT_HOST_PORT, DEFAULT_KEEP_ALIVE,
	   DEFAULT_MAX_CONNECTION_AGE, DEFAULT_PROXY_PORT,
	   BUG_REPORT_EMAIL);
}

static int
wait_for_connection_on_socket (int s)
{
  struct sockaddr addr;
  socklen_t len;
  int t;

  len = sizeof addr;
  t = accept (s, &addr, &len);
  if (t == -1)
    return -1;

  return t;
}

static void
parse_arguments (int argc, char **argv, Arguments *arg)
{
  int c;

  /* defaults */

  arg->me = argv[0];
  arg->device = NULL;
  arg->forward_port = -1;
  arg->host_name = NULL;
  arg->host_port = DEFAULT_HOST_PORT;
  arg->proxy_name = NO_PROXY;
  arg->proxy_port = DEFAULT_PROXY_PORT;
  arg->proxy_buffer_size = NO_PROXY_BUFFER;
  arg->proxy_buffer_timeout = -1;
  arg->content_length = DEFAULT_CONTENT_LENGTH;
  arg->strict_content_length = FALSE;
  arg->keep_alive = DEFAULT_KEEP_ALIVE;
  arg->max_connection_age = DEFAULT_CONNECTION_MAX_TIME;
  arg->proxy_authorization = NULL;
  arg->user_agent = NULL;
  
  for (;;)
    {
      int option_index = 0;
      static struct option long_options[] =
      {
	{ "help", no_argument, 0, 'h' },
	{ "version", no_argument, 0, 'V' },
#ifdef DEBUG_MODE
	{ "debug", required_argument, 0, 'D' },
	{ "logfile", required_argument, 0, 'l' },
#endif
	{ "proxy", required_argument, 0, 'P' },
	{ "device", required_argument, 0, 'd' },
	{ "timeout", required_argument, 0, 'T' },
	{ "keep-alive", required_argument, 0, 'k' },
	{ "user-agent", required_argument, 0, 'U' },
	{ "forward-port", required_argument, 0, 'F' },
	{ "content-length", required_argument, 0, 'c' },
	{ "strict-content-length", no_argument, 0, 'S' },
	{ "proxy-buffer-size", required_argument, 0, 'B' },
	{ "proxy-authorization", required_argument, 0, 'A' },
	{ "max-connection-age", required_argument, 0, 'M' },
	{ "proxy-authorization-file", required_argument, 0, 'z' },
	{ 0, 0, 0, 0 }
      };

      static const char *short_options = "A:B:c:d:F:hk:M:P:ST:U:Vz:"
#ifdef DEBUG_MODE
	"D:l:"
#endif
	;

      c = getopt_long (argc, argv, short_options,
		       long_options, &option_index);
      if (c == -1)
	break;

      switch (c)
	{
	case 0:
	  printf ("option %s", long_options[option_index].name);
	  if (optarg)
	    printf (" with arg %s", optarg);
	  printf ("\n");
	  break;

	case 'A':
	  arg->proxy_authorization = optarg;
	  break;

	case 'B':
	  arg->proxy_buffer_size = atoi_with_postfix (optarg);
	  break;

	case 'c':
	  arg->content_length = atoi_with_postfix (optarg);
	  break;

	case 'd':
	  arg->device = optarg;
	  break;

#ifdef DEBUG_MODE
	case 'D':
	  if (optarg)
	    debug_level = atoi (optarg);
	  else
	    debug_level = 1;
	  break;

	case 'l':
	  debug_file = fopen (optarg, "w");
	  if (debug_file == NULL)
	    {
	      fprintf (stderr, "%s: couldn't open file %s for writing\n",
		       arg->me, optarg);
	      exit (1);
	    }
	  break;
#endif

	case 'F':
	  arg->forward_port = atoi (optarg);
	  break;

	case 'k':
	  arg->keep_alive = atoi (optarg);
	  break;

	case 'M':
	  arg->max_connection_age = atoi (optarg);
	  break;

	case 'h':
	  usage (stdout, arg->me);
	  exit (0);

	case 'P':
	  name_and_port (optarg, &arg->proxy_name, &arg->proxy_port);
	  if (arg->proxy_port == -1)
	    arg->proxy_port = DEFAULT_PROXY_PORT;
	  if (arg->proxy_buffer_timeout == -1)
	    arg->proxy_buffer_timeout = DEFAULT_PROXY_BUFFER_TIMEOUT;
	  break;

	case 'S':
	  arg->strict_content_length = TRUE;
	  break;

	case 'T':
	  arg->proxy_buffer_timeout = atoi (optarg);
	  break;

	case 'U':
	  arg->user_agent = optarg;
	  break;

	case 'V':
	  printf ("htc (%s) %s\n", PACKAGE, VERSION);
	  exit (0);

	case 'z':
	  {
	    struct stat s;
	    char *auth;
	    int f;

	    f = open (optarg, O_RDONLY);
	    if (f == -1)
	      {
		printf ("couldn't open %s: %s\n", optarg, strerror (errno));
		exit (1);
	      }

	    if (fstat (f, &s) == -1)
	      {
		printf ("error fstating %s: %s\n", optarg, strerror (errno));
		exit (1);
	      }

	    auth = malloc (s.st_size + 1);
	    if (auth == NULL)
	      {
		printf ("out of memory whilst allocating"
			"authentication string\n");
		exit (1);
	      }

	    if (read_all (f, auth, s.st_size) == -1)
	      {
		printf ("error reading %s: %s\n", optarg, strerror (errno));
		exit (1);
	      }

	    /*
	     * If file ends with a "\r\n" or "\n", chop them off.
	     */
	    if (s.st_size >= 1 && auth[s.st_size - 1] == '\n')
	      {
		s.st_size -=
		  (s.st_size >= 2 && auth[s.st_size - 2] == '\r') ? 2 : 1;
	      }

	    auth[s.st_size] = 0;
	    arg->proxy_authorization = auth;
	  }
	  break;

	case '?':
	  break;

	default:
	  printf ("?? getopt returned character code 0%o ??\n", c);
	}
    }

  if (optind == argc - 1)
    {
      name_and_port (argv[optind], &arg->host_name, &arg->host_port);
      if (arg->host_port == -1)
	arg->host_port = DEFAULT_HOST_PORT;
    }