/*
 *  OpenVPN -- An application to securely tunnel IP networks
 *             over a single TCP/UDP port, with support for SSL/TLS-based
 *             session authentication and key exchange,
 *             packet encryption, packet authentication, and
 *             packet compression.
 *
 *  Copyright (C) 2002-2008 OpenVPN Technologies, Inc. <sales@openvpn.net>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2
 *  as published by the Free Software Foundation.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program (see the file COPYING included with this
 *  distribution); if not, write to the Free Software Foundation, Inc.,
 *  59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include "syshead.h"

#include "common.h"
#include "misc.h"
#include "win32.h"
#include "socket.h"
#include "fdmisc.h"
#include "proxy.h"
#include "base64.h"
#include "ntlm.h"

#ifdef WIN32
#include "ieproxy.h"
#endif

#include "memdbg.h"

#ifdef ENABLE_HTTP_PROXY

/* cached proxy username/password */
static struct user_pass static_proxy_user_pass;

static bool
recv_line (socket_descriptor_t sd,
	   char *buf,
	   int len,
	   const int timeout_sec,
	   const bool verbose,
	   struct buffer *lookahead,
	   volatile int *signal_received)
{
  struct buffer la;
  int lastc = 0;

  CLEAR (la);
  if (lookahead)
    la = *lookahead;

  while (true)
    {
      int status;
      ssize_t size;
      fd_set reads;
      struct timeval tv;
      uint8_t c;

      if (buf_defined (&la))
	{
	  ASSERT (buf_init (&la, 0));
	}

      FD_ZERO (&reads);
      FD_SET (sd, &reads);
      tv.tv_sec = timeout_sec;
      tv.tv_usec = 0;

      status = select (sd + 1, &reads, NULL, NULL, &tv);

      get_signal (signal_received);
      if (*signal_received)
	goto error;

      /* timeout? */
      if (status == 0)
	{
	  if (verbose)
	    msg (D_LINK_ERRORS | M_ERRNO_SOCK, "recv_line: TCP port read timeout expired");
	  goto error;
	}

      /* error */
      if (status < 0)
	{
	  if (verbose)
	    msg (D_LINK_ERRORS | M_ERRNO_SOCK, "recv_line: TCP port read failed on select()");
	  goto error;
	}

      /* read single char */
      size = recv (sd, &c, 1, MSG_NOSIGNAL);

      /* error? */
      if (size != 1)
	{
	  if (verbose)
	    msg (D_LINK_ERRORS | M_ERRNO_SOCK, "recv_line: TCP port read failed on recv()");
	  goto error;
	}

#if 0
      if (isprint(c))
	msg (M_INFO, "PROXY: read '%c' (%d)", c, (int)c);
      else
	msg (M_INFO, "PROXY: read (%d)", (int)c);
#endif

      /* store char in buffer */
      if (len > 1)
	{
	  *buf++ = c;
	  --len;
	}

      /* also store char in lookahead buffer */
      if (buf_defined (&la))
	{
	  buf_write_u8 (&la, c);
	  if (!isprint(c) && !isspace(c)) /* not ascii? */
	    {
	      if (verbose)
		msg (D_LINK_ERRORS | M_ERRNO_SOCK, "recv_line: Non-ASCII character (%d) read on recv()", (int)c);
	      *lookahead = la;
	      return false;
	    }
	}

      /* end of line? */
      if (lastc == '\r' && c == '\n')
	break;

      lastc = c;
    }

  /* append trailing null */
  if (len > 0)
    *buf++ = '\0';

  return true;

 error:
  return false;
}

static bool
send_line (socket_descriptor_t sd,
	   const char *buf)
{
  const ssize_t size = send (sd, buf, strlen (buf), MSG_NOSIGNAL);
  if (size != (ssize_t) strlen (buf))
    {
      msg (D_LINK_ERRORS | M_ERRNO_SOCK, "send_line: TCP port write failed on send()");
      return false;
    }
  return true;
}

static bool
send_line_crlf (socket_descriptor_t sd,
		const char *src)
{
  bool ret;

  struct buffer buf = alloc_buf (strlen (src) + 3);
  ASSERT (buf_write (&buf, src, strlen (src)));
  ASSERT (buf_write (&buf, "\r\n", 3));
  ret = send_line (sd, BSTR (&buf));
  free_buf (&buf);
  return ret;
}

static bool
send_crlf (socket_descriptor_t sd)
{
  return send_line_crlf (sd, "");
}

uint8_t *
make_base64_string2 (const uint8_t *str, int src_len, struct gc_arena *gc)
{
  uint8_t *ret = NULL;
  char *b64out = NULL;
  ASSERT (base64_encode ((const void *)str, src_len, &b64out) >= 0);
  ret = (uint8_t *) string_alloc (b64out, gc);
  free (b64out);
  return ret;
}

uint8_t *
make_base64_string (const uint8_t *str, struct gc_arena *gc)
{
  return make_base64_string2 (str, strlen ((const char *)str), gc);
}

static const char *
username_password_as_base64 (const struct http_proxy_info *p,
			     struct gc_arena *gc)
{
  struct buffer out = alloc_buf_gc (strlen (p->up.username) + strlen (p->up.password) + 2, gc);
  ASSERT (strlen (p->up.username) > 0);
  buf_printf (&out, "%s:%s", p->up.username, p->up.password);
  return (const char *)make_base64_string ((const uint8_t*)BSTR (&out), gc);
}

static void
get_user_pass_http (struct http_proxy_info *p, const bool force)
{
  if (!static_proxy_user_pass.defined || force)
    {
      get_user_pass (&static_proxy_user_pass,
		     p->options.auth_file,
		     "HTTP Proxy",
		     GET_USER_PASS_MANAGEMENT);
      p->up = static_proxy_user_pass;
    }
}

struct http_proxy_info *
http_proxy_new (const struct http_proxy_options *o,
		struct auto_proxy_info *auto_proxy_info)
{
  struct http_proxy_info *p;
  struct http_proxy_options opt;

  if (auto_proxy_info)
    {
      if (o && o->server)
	{
	  /* if --http-proxy explicitly given, disable auto-proxy */
	  auto_proxy_info = NULL;
	}
      else
	{
	  /* if no --http-proxy explicitly given and no auto settings, fail */
	  if (!auto_proxy_info->http.server)
	    return NULL;

	  if (o)
	    {
	      opt = *o;
	    }
	  else
	    {
	      CLEAR (opt);
	  
	      /* These settings are only used for --auto-proxy */
	      opt.timeout = 5;
	      opt.http_version = "1.0";
	    }

	  opt.server = auto_proxy_info->http.server;
	  opt.port = auto_proxy_info->http.port;
	  opt.auth_retry = true;

	  o = &opt;
	}
    }

  if (!o || !o->server)
    msg (M_FATAL, "HTTP_PROXY: server not specified");

  ASSERT (legal_ipv4_port (o->port));

  ALLOC_OBJ_CLEAR (p, struct http_proxy_info);
  p->options = *o;

  /* parse authentication method */
  p->auth_method = HTTP_AUTH_NONE;
  if (o->auth_method_string)
    {
      if (!strcmp (o->auth_method_string, "none"))
	p->auth_method = HTTP_AUTH_NONE;
      else if (!strcmp (o->auth_method_string, "basic"))
	p->auth_method = HTTP_AUTH_BASIC;
      else if (!strcmp (o->auth_method_string, "ntlm"))
	p->auth_method = HTTP_AUTH_NTLM;
      else if (!strcmp (o->auth_method_string, "ntlm2"))
	p->auth_method = HTTP_AUTH_NTLM2;
      else
	msg (M_FATAL, "ERROR: unknown HTTP authentication method: '%s' -- only the 'none', 'basic', 'ntlm', or 'ntlm2' methods are currently supported",
	     o->auth_method_string);
    }

  /* only basic and NTLM/NTLMv2 authentication supported so far */
  if (p->auth_method == HTTP_AUTH_BASIC || p->auth_method == HTTP_AUTH_NTLM || p->auth_method == HTTP_AUTH_NTLM2)
    {
      get_user_pass_http (p, true);
    }

#if !NTLM
  if (p->auth_method == HTTP_AUTH_NTLM || p->auth_method == HTTP_AUTH_NTLM2)
    msg (M_FATAL, "Sorry, this version of " PACKAGE_NAME " was built without NTLM Proxy support.");
#endif

  p->defined = true;
  return p;
}

void
http_proxy_close (struct http_proxy_info *hp)
{
  free (hp);
}

bool
establish_http_proxy_passthru (struct http_proxy_info *p,
			       socket_descriptor_t sd, /* already open to proxy */
			       const char *host,       /* openvpn server remote */
			       const int port,         /* openvpn server port */
			       struct buffer *lookahead,
			       volatile int *signal_received)
{
  struct gc_arena gc = gc_new ();
  char buf[256];
  char buf2[128];
  char get[80];
  int status;
  int nparms;
  bool ret = false;

  /* get user/pass if not previously given or if --auto-proxy is being used */
  if (p->auth_method == HTTP_AUTH_BASIC
      || p->auth_method == HTTP_AUTH_NTLM)
    get_user_pass_http (p, false);

  /* format HTTP CONNECT message */
  openvpn_snprintf (buf, sizeof(buf), "CONNECT %s:%d HTTP/%s",
		    host,
		    port,
		    p->options.http_version);

  msg (D_PROXY, "Send to HTTP proxy: '%s'", buf);

  /* send HTTP CONNECT message to proxy */
  if (!send_line_crlf (sd, buf))
    goto error;

  /* send User-Agent string if provided */
  if (p->options.user_agent)
    {
      openvpn_snprintf (buf, sizeof(buf), "User-Agent: %s",
			p->options.user_agent);
      if (!send_line_crlf (sd, buf))
	goto error;
    }

  /* auth specified? */
  switch (p->auth_method)
    {
    case HTTP_AUTH_NONE:
      break;

    case HTTP_AUTH_BASIC:
      openvpn_snprintf (buf, sizeof(buf), "Proxy-Authorization: Basic %s",
			username_password_as_base64 (p, &gc));
      msg (D_PROXY, "Attempting Basic Proxy-Authorization");
      dmsg (D_SHOW_KEYS, "Send to HTTP proxy: '%s'", buf);
      openvpn_sleep (1);
      if (!send_line_crlf (sd, buf))
	goto error;
      break;

#if NTLM
    case HTTP_AUTH_NTLM:
    case HTTP_AUTH_NTLM2:
      /* keep-alive connection */
      openvpn_snprintf (buf, sizeof(buf), "Proxy-Connection: Keep-Alive");
      if (!send_line_crlf (sd, buf))
	goto error;

      openvpn_snprintf (buf, sizeof(buf), "Proxy-Authorization: NTLM %s",
			ntlm_phase_1 (p, &gc));
      msg (D_PROXY, "Attempting NTLM Proxy-Authorization phase 1");
      dmsg (D_SHOW_KEYS, "Send to HTTP proxy: '%s'", buf);
      openvpn_sleep (1);
      if (!send_line_crlf (sd, buf))
	goto error;
      break;
#endif

    default:
      ASSERT (0);
    }

  /* send empty CR, LF */
  openvpn_sleep (1);
  if (!send_crlf (sd))
    goto error;

  /* receive reply from proxy */
  if (!recv_line (sd, buf, sizeof(buf), p->options.timeout, true, NULL, signal_received))
    goto error;

  /* remove trailing CR, LF */
  chomp (buf);

  msg (D_PROXY, "HTTP proxy returned: '%s'", buf);

  /* parse return string */
  nparms = sscanf (buf, "%*s %d", &status);

  /* check for a "407 Proxy Authentication Required" response */
  if (nparms >= 1 && status == 407)
    {
      msg (D_PROXY, "Proxy requires authentication");

      /* check for NTLM */
      if (p->auth_method == HTTP_AUTH_NTLM || p->auth_method == HTTP_AUTH_NTLM2)
        {
#if NTLM
          /* look for the phase 2 response */

          while (true)
            {
              if (!recv_line (sd, buf, sizeof(buf), p->options.timeout, true, NULL, signal_received))
                goto error;
              chomp (buf);
              msg (D_PROXY, "HTTP proxy returned: '%s'", buf);

              openvpn_snprintf (get, sizeof get, "%%*s NTLM %%%ds", (int) sizeof (buf2) - 1);
              nparms = sscanf (buf, get, buf2);
              buf2[127] = 0; /* we only need the beginning - ensure it's null terminated. */

              /* check for "Proxy-Authenticate: NTLM TlRM..." */
              if (nparms == 1)
                {
                  /* parse buf2 */
                  msg (D_PROXY, "auth string: '%s'", buf2);
                  break;
                }
            }
          /* if we are here then auth string was got */
          msg (D_PROXY, "Received NTLM Proxy-Authorization phase 2 response");

          /* receive and discard everything else */
          while (recv_line (sd, NULL, 0, p->options.timeout, true, NULL, signal_received))
            ;

          /* now send the phase 3 reply */

          /* format HTTP CONNECT message */
          openvpn_snprintf (buf, sizeof(buf), "CONNECT %s:%d HTTP/%s",
			    host,
			    port,
			    p->options.http_version);

          msg (D_PROXY, "Send to HTTP proxy: '%s'", buf);

          /* send HTTP CONNECT message to proxy */
          if (!send_line_crlf (sd, buf))
            goto error;

          /* keep-alive connection */
          openvpn_snprintf (buf, sizeof(buf), "Proxy-Connection: Keep-Alive");
          if (!send_line_crlf (sd, buf))
            goto error;

          
          /* send HOST etc, */
          openvpn_sleep (1);
          openvpn_snprintf (buf, sizeof(buf), "Host: %s", host);
          msg (D_PROXY, "Send to HTTP proxy: '%s'", buf);
          if (!send_line_crlf (sd, buf))
            goto error;

          msg (D_PROXY, "Attempting NTLM Proxy-Authorization phase 3");
	  {
	    const char *np3 = ntlm_phase_3 (p, buf2, &gc);
	    if (!np3)
	      {
		msg (D_PROXY, "NTLM Proxy-Authorization phase 3 failed: received corrupted data from proxy server");
		goto error;
	      }
	    openvpn_snprintf (buf, sizeof(buf), "Proxy-Authorization: NTLM %s", np3);
	  }

          msg (D_PROXY, "Send to HTTP proxy: '%s'", buf);
          openvpn_sleep (1);
          if (!send_line_crlf (sd, buf))
	    goto error;
          /* ok so far... */
          /* send empty CR, LF */
          openvpn_sleep (1);
          if (!send_crlf (sd))
            goto error;

          /* receive reply from proxy */
          if (!recv_line (sd, buf, sizeof(buf), p->options.timeout, true, NULL, signal_received))
            goto error;

          /* remove trailing CR, LF */
          chomp (buf);

          msg (D_PROXY, "HTTP proxy returned: '%s'", buf);

          /* parse return string */
          nparms = sscanf (buf, "%*s %d", &status);
#else
	  ASSERT (0); /* No NTLM support */
#endif
	}
      else if (p->auth_method == HTTP_AUTH_NONE && p->options.auth_retry)
	{
	  /*
	   * Proxy needs authentication, but we don't have a user/pass.
	   * Now we will change p->auth_method and return true so that
	   * our caller knows to call us again on a newly opened socket.
	   * JYFIXME: This code needs to check proxy error output and set
	   * JYFIXME: p->auth_method = HTTP_AUTH_NTLM if necessary.
	   */
	  p->auth_method = HTTP_AUTH_BASIC;
	  ret = true;
	  goto done;
	}
      else
	goto error;
    }


  /* check return code, success = 200 */
  if (nparms < 1 || status != 200)
    {
      msg (D_LINK_ERRORS, "HTTP proxy returned bad status");
#if 0
      /* DEBUGGING -- show a multi-line HTTP error response */
      while (true)
	{
	  if (!recv_line (sd, buf, sizeof (buf), p->options.timeout, true, NULL, signal_received))
	    goto error;
	  chomp (buf);
	  msg (D_PROXY, "HTTP proxy returned: '%s'", buf);
	}
#endif
      goto error;
    }

  /* receive line from proxy and discard */
  if (!recv_line (sd, NULL, 0, p->options.timeout, true, NULL, signal_received))
    goto error;

  /*
   * Toss out any extraneous chars, but don't throw away the
   * start of the OpenVPN data stream (put it in lookahead).
   */
  while (recv_line (sd, NULL, 0, 2, false, lookahead, signal_received))
    ;

#if 0
  if (lookahead && BLEN (lookahead))
    msg (M_INFO, "HTTP PROXY: lookahead: %s", format_hex (BPTR (lookahead), BLEN (lookahead), 0));
#endif

 done:
  gc_free (&gc);
  return ret;

 error:
  /* on error, should we exit or restart? */
  if (!*signal_received)
    *signal_received = (p->options.retry ? SIGUSR1 : SIGTERM); /* SOFT-SIGUSR1 -- HTTP proxy error */
  gc_free (&gc);
  return ret;
}

#else
static void dummy(void) {}
#endif /* ENABLE_HTTP_PROXY */

#ifdef GENERAL_PROXY_SUPPORT

#ifdef WIN32

#if 0
char *
get_windows_internet_string (const DWORD dwOption, struct gc_arena *gc)
{
  DWORD size = 0;
  char *ret = NULL;

  /* Initially, get size of return buffer */
  InternetQueryOption (NULL, dwOption, NULL, &size);
  if (size)
    {
      /* Now get actual info */
      ret = (INTERNET_PROXY_INFO *) gc_malloc (size, false, gc);
      if (!InternetQueryOption (NULL, dwOption, (LPVOID) ret, &size))
	ret = NULL;
    }
  return ret;
}
#endif

static INTERNET_PROXY_INFO *
get_windows_proxy_settings (struct gc_arena *gc)
{
  DWORD size = 0;
  INTERNET_PROXY_INFO *ret = NULL;

  /* Initially, get size of return buffer */
  InternetQueryOption (NULL, INTERNET_OPTION_PROXY, NULL, &size);
  if (size)
    {
      /* Now get actual info */
      ret = (INTERNET_PROXY_INFO *) gc_malloc (size, false, gc);
      if (!InternetQueryOption (NULL, INTERNET_OPTION_PROXY, (LPVOID) ret, &size))
	ret = NULL;
    }
  return ret;
}

static const char *
parse_windows_proxy_setting (const char *str, struct auto_proxy_info_entry *e, struct gc_arena *gc)
{
  char buf[128];
  const char *ret = NULL;
  struct buffer in;

  CLEAR (*e);

  buf_set_read (&in, (const uint8_t *)str, strlen (str));

  if (strchr (str, '=') != NULL)
    {
      if (buf_parse (&in, '=', buf, sizeof (buf)))
	ret = string_alloc (buf, gc);
    }
	
  if (buf_parse (&in, ':', buf, sizeof (buf)))
    e->server = string_alloc (buf, gc);

  if (e->server && buf_parse (&in, '\0', buf, sizeof (buf)))
    e->port = atoi (buf);

  return ret;
}

static void
parse_windows_proxy_setting_list (const char *str, const char *type, struct auto_proxy_info_entry *e, struct gc_arena *gc)
{
  struct gc_arena gc_local = gc_new ();
  struct auto_proxy_info_entry el;

  CLEAR (*e);
  if (type)
    {
      char buf[128];
      struct buffer in;

      buf_set_read (&in, (const uint8_t *)str, strlen (str));
      if (strchr (str, '=') != NULL)
	{
	  while (buf_parse (&in, ' ', buf, sizeof (buf)))
	    {
	      const char *t = parse_windows_proxy_setting (buf, &el, &gc_local);
	      if (t && !strcmp (t, type))
		goto found;
	    }
	}
    }
  else
    {
      if (!parse_windows_proxy_setting (str, &el, &gc_local))
	goto found;
    }
  goto done;

 found:
  if (el.server && el.port > 0)
    {
      e->server = string_alloc (el.server, gc);
      e->port = el.port;
    }

 done:
  gc_free (&gc_local);
}

static const char *
win_proxy_access_type (const DWORD dwAccessType)
{
  switch (dwAccessType)
    {
    case INTERNET_OPEN_TYPE_DIRECT:
      return "INTERNET_OPEN_TYPE_DIRECT";
    case INTERNET_OPEN_TYPE_PROXY:
      return "INTERNET_OPEN_TYPE_PROXY";
    default:
      return "[UNKNOWN]";
    }
}

void
show_win_proxy_settings (const int msglevel)
{
  INTERNET_PROXY_INFO *info;
  struct gc_arena gc = gc_new ();

  info = get_windows_proxy_settings (&gc);
  msg (msglevel, "PROXY INFO: %s %s",
       win_proxy_access_type (info->dwAccessType),
       info->lpszProxy ? info->lpszProxy : "[NULL]");

  gc_free (&gc);
}

struct auto_proxy_info *
get_proxy_settings (char **err, struct gc_arena *gc)
{
  struct gc_arena gc_local = gc_new ();
  INTERNET_PROXY_INFO *info;
  struct auto_proxy_info *pi;

  ALLOC_OBJ_CLEAR_GC (pi, struct auto_proxy_info, gc);

  if (err)
    *err = NULL;

  info = get_windows_proxy_settings (&gc_local);

  if (!info)
    {
      if (err)
	*err = "PROXY: failed to obtain windows proxy info";
      goto done;
    }

  switch (info->dwAccessType)
    {
    case INTERNET_OPEN_TYPE_DIRECT:
      break;
    case INTERNET_OPEN_TYPE_PROXY:
      if (!info->lpszProxy)
	break;
      parse_windows_proxy_setting_list (info->lpszProxy, NULL, &pi->http, gc);
      if (!pi->http.server)
	parse_windows_proxy_setting_list (info->lpszProxy, "http", &pi->http, gc);
      parse_windows_proxy_setting_list (info->lpszProxy, "socks", &pi->socks, gc);
      break;
    default:
      if (err)
	*err = "PROXY: unknown proxy type";
      break;
    }

 done:
  gc_free (&gc_local);
  return pi;
}

#else

struct auto_proxy_info *
get_proxy_settings (char **err, struct gc_arena *gc)
{
#if 1
  if (err)
    *err = string_alloc ("PROXY: automatic detection not supported on this OS", gc);
  return NULL;
#else /* test --auto-proxy feature */
  struct auto_proxy_info *pi;
  ALLOC_OBJ_CLEAR_GC (pi, struct auto_proxy_info, gc);
  pi->http.server = "10.10.0.2";
  pi->http.port = 4000;
  return pi;
#endif
}

#endif

#endif /* GENERAL_PROXY_SUPPORT */