--- ../mosh/src/frontend/mosh.cc	2016-04-29 00:42:24.837700203 +1000
+++ ./src/frontend/mosh.cc	2016-04-29 00:40:13.346294286 +1000
@@ -0,0 +1,519 @@
+//   Mosh: the mobile shell
+//   Copyright 2012 Keith Winstein
+//
+//   This program is free software: you can redistribute it and/or modify
+//   it under the terms of the GNU General Public License as published by
+//   the Free Software Foundation, either version 3 of the License, or
+//   (at your option) any later version.
+//
+//   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.  If not, see <http://www.gnu.org/licenses/>.
+
+#include "config.h"
+#include <limits.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <stdarg.h>
+#include <string.h>
+#include <vector>
+#include <map>
+#include <stdio.h>
+#include <string>
+#include <sys/socket.h>
+#include <getopt.h>
+#include <arpa/inet.h>
+#include <netdb.h>
+#include <signal.h>
+#include <errno.h>
+#include <sys/ioctl.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <termios.h>
+#if HAVE_PTY_H
+#include <pty.h>
+#elif HAVE_UTIL_H
+#include <util.h>
+#endif
+
+#if OPENPTY_IN_LIBUTIL
+#include <libutil.h>
+#endif
+
+#if !HAVE_GETLINE
+ssize_t getline( char ** restrict linep,
+    size_t * restrict linecapp,
+    FILE * restrict stream ) {
+  size_t num_read = 0;
+  if ( !linep || !linecapp ) {
+    errno = EINVAL;
+    return -1;
+  }
+  if ( !*linep ) {
+    *linecapp = 0;
+  }
+  while ( 1 ) {
+    int ch = getc( stream );
+    if ( ch == EOF ) {
+      return num_read ? (ssize_t)num_read : -1;
+    }
+    if ( num_read + 1 >= *linecapp ) {
+      char *new_line = *linep;
+      size_t new_linecap = *linecapp;
+      if ( *linecapp > SSIZE_MAX - 4096 ) {
+        errno = EOVERFLOW;
+        return -1;
+      }
+      new_linecap += 4096;
+      new_line = (char *)realloc( new_line, new_linecap );
+      if ( !new_line ) {
+        return -1;
+      }
+      *linecapp = new_linecap;
+      *linep = new_line;
+    }
+    (*linep)[num_read++] = ch;
+    // so that we can safely return at any time,
+    (*linep)[num_read] = '\0';
+    if (ch == '\n') {
+      return num_read;
+    }
+  }
+  return -1;
+}
+#endif
+
+using namespace std;
+
+inline string shell_quote_string( const string &x )
+{
+  string result = "'";
+  string rest = x;
+  while ( rest.size() ) {
+    size_t good_part = rest.find( "'" );
+    result += rest.substr( 0, good_part );
+    if ( good_part != string::npos ) {
+      result += "'\\''";
+      rest = rest.substr( good_part + 1 );
+    } else {
+      break;
+    }
+  }
+  return result + "'";
+}
+
+template <typename SequenceT>
+inline string shell_quote( const SequenceT &sequence )
+{
+  string result;
+  for ( typename SequenceT::const_iterator i = sequence.begin();
+        i != sequence.end();
+        i++ ) {
+    result += shell_quote_string( *i ) + " ";
+  }
+  return result.substr( 0, result.size() - 1 );
+}
+
+void die( const char *format, ... ) {
+  va_list args;
+  va_start( args, format );
+  vfprintf( stderr, format, args );
+  va_end( args );
+  fprintf( stderr, "\n" );
+  exit( 255 );
+}
+
+static const char *usage_format =
+"Usage: %s [options] [--] [user@]host [command...]\n"
+"        --client=PATH        mosh client on local machine\n"
+"                                (default: mosh-client)\n"
+"        --server=PATH        mosh server on remote machine\n"
+"                                (default: mosh-server)\n"
+"\n"
+"        --predict=adaptive   local echo for slower links [default]\n"
+"-a      --predict=always     use local echo even on fast links\n"
+"-n      --predict=never      never use local echo\n"
+"\n"
+"-p NUM  --port=NUM           server-side UDP port\n"
+"\n"
+"-P NUM  --ssh-port=NUM       ssh server port\n"
+"                                (default: let the ssh command choose)\n"
+"\n"
+"        --ssh=COMMAND        ssh command to run when setting up session\n"
+"                                (example: \"ssh -p 2222\")\n"
+"                                (default: \"ssh\")\n"
+"\n"
+"        --help               this message\n"
+"        --version            version and copyright information\n"
+"\n"
+"Please report bugs to mosh-devel@mit.edu.\n"
+"Mosh home page: http://mosh.mit.edu";
+
+static const char *version_format =
+"mosh %s\n"
+"Copyright 2012 Keith Winstein <mosh-devel@mit.edu>\n"
+"License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.\n"
+"This is free software: you are free to change and redistribute it.\n"
+"There is NO WARRANTY, to the extent permitted by law.";
+
+static const char *key_valid_char_set =
+"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789/+";
+
+static char *argv0;
+
+void predict_check( const string &predict, bool env_set )
+{
+  if ( predict != "adaptive" &&
+       predict != "always" &&
+       predict != "never" ) {
+    fprintf( stderr, "%s: Unknown mode \"%s\"%s.\n", argv0, predict.c_str(),
+        env_set ? " (MOSH_PREDICTION_DISPLAY in environment)" : "" );
+    die( usage_format, argv0 );
+  }
+}
+
+void cat( int ifd, int ofd )
+{
+  char buf[4096];
+  ssize_t n;
+  while ( 1 ) {
+    n = read( ifd, buf, sizeof( buf ) );
+    if ( n==-1 ) {
+      if (errno == EINTR ) {
+        continue;
+      }
+      break;
+    }
+    if ( n==0 ) {
+      break;
+    }
+    n = write( ofd, buf, n );
+    if ( n==-1 ) {
+      break;
+    }
+  }
+}
+
+bool valid_port(string port) {
+  if ( port.size() ) {
+    return port.find_first_not_of( "0123456789" ) == string::npos &&
+         atoi( port.c_str() ) > 0 &&
+         atoi( port.c_str() ) <= 65535;
+  }
+  return true; // consider no port to be the default value
+}
+
+int main( int argc, char *argv[] )
+{
+  argv0 = argv[0];
+  string client = "mosh-client";
+  string server = "mosh-server";
+  string ssh = "ssh";
+  string predict, port_request, ssh_port;
+  int help=0, version=0, fake_proxy=0;
+
+  static struct option long_options[] =
+  {
+    { "client",      required_argument,  0,              'c' },
+    { "server",      required_argument,  0,              's' },
+    { "predict",     required_argument,  0,              'r' },
+    { "port",        required_argument,  0,              'p' },
+    { "ssh-port",    required_argument,  0,              'P' },
+    { "ssh",         required_argument,  0,              'S' },
+    { "help",        no_argument,        &help,           1  },
+    { "version",     no_argument,        &version,        1  },
+    { "fake-proxy!", no_argument,        &fake_proxy,     1  },
+    { 0, 0, 0, 0 }
+  };
+  while ( 1 ) {
+    int option_index = 0;
+    int c = getopt_long( argc, argv, "anp:P:",
+        long_options, &option_index );
+    if ( c == -1 ) {
+      break;
+    }
+
+    switch ( c ) {
+      case 0:
+        // flag has been set
+        break;
+      case 'c':
+        client = optarg;
+        break;
+      case 's':
+        server = optarg;
+        break;
+      case 'r':
+        predict = optarg;
+        break;
+      case 'p':
+        port_request = optarg;
+        break;
+      case 'P':
+        ssh_port = optarg;
+        break;
+      case 'S':
+        ssh = optarg;
+        break;
+      case 'a':
+        predict = "always";
+        break;
+      case 'n':
+        predict = "never";
+        break;
+      default:
+        die( usage_format, argv[0] );
+    }
+  }
+
+  if ( help ) {
+    die( usage_format, argv[0] );
+  }
+  if ( version ) {
+    die( version_format, PACKAGE_VERSION );
+  }
+
+  if ( predict.size() ) {
+    predict_check( predict, 0 );
+  } else if ( getenv( "MOSH_PREDICTION_DELAY" ) ) {
+    predict = getenv( "MOSH_PREDICTION_DELAY" );
+    predict_check( predict, 1 );
+  } else {
+    predict = "adaptive";
+    predict_check( predict, 0 );
+  }
+
+  if(!valid_port(port_request)) {
+    die( "%s: Server-side port (%s) must be within valid range [0..65535].",
+        argv[0],
+        port_request.c_str() );
+  }
+
+  if(!valid_port(ssh_port)) {
+    die( "%s: SSH port (%s) must be within valid range [0..65535].",
+        argv[0],
+        ssh_port.c_str() );
+  }
+
+  unsetenv( "MOSH_PREDICTION_DISPLAY" );
+
+  if ( fake_proxy ) {
+    string host = argv[optind++];
+    string port = argv[optind++];
+
+    int sockfd = -1;
+    struct addrinfo hints, *servinfo, *p;
+    int rv;
+
+    memset( &hints, 0, sizeof( hints ) );
+    hints.ai_socktype = SOCK_STREAM;
+
+    if ( ( rv = getaddrinfo( host.c_str(),
+                             port.c_str(),
+                             &hints,
+                             &servinfo ) ) != 0 ) {
+      die( "%s: Could not resolve hostname %s: getaddrinfo: %s",
+           argv[0],
+           host.c_str(),
+           gai_strerror( rv ) );
+    }
+
+    int try_family = AF_INET;
+    // loop through all the results and connect to the first we can
+    for ( p = servinfo; p != NULL || try_family == AF_INET; p = p->ai_next ) {
+      if(p == NULL && try_family == AF_INET) { // start over and try AF_INET6
+        p = servinfo;
+        try_family = AF_INET6;
+      }
+      if(p == NULL) {
+        break; // servinfo == NULL
+      }
+
+      if(p->ai_family != try_family) {
+        continue;
+      }
+
+      if ( ( sockfd = socket( p->ai_family, SOCK_STREAM, IPPROTO_TCP ) ) == -1 ) {
+        continue;
+      }
+
+      if ( connect( sockfd, p->ai_addr, p->ai_addrlen ) == -1 ) {
+        close( sockfd );
+        continue;
+      }
+
+      char host[NI_MAXHOST], service[NI_MAXSERV];
+      if ( getnameinfo( p->ai_addr, p->ai_addrlen,
+            host, NI_MAXHOST,
+            service, NI_MAXSERV,
+            NI_NUMERICSERV | NI_NUMERICHOST ) == -1 ) {
+        die( "Couldn't get host name info" );
+      }
+
+      fprintf( stderr, "MOSH IP %s\n", host );
+      break; // if we get here, we must have connected successfully
+    }
+
+    if ( p == NULL ) {
+      // looped off the end of the list with no connection
+      die( "%s: failed to connect to host %s port %s",
+            argv[0], host.c_str(), port.c_str() );
+    }
+
+    freeaddrinfo( servinfo ); // all done with this structure
+
+    int pid = fork();
+    if ( pid == -1 ) {
+      die( "%s: fork: %d", argv[0], errno );
+    }
+    if ( pid == 0 ) {
+      cat( sockfd, 1 );
+      shutdown( sockfd, 0 );
+      exit( 0 );
+    }
+    signal( SIGHUP, SIG_IGN );
+    cat( 0, sockfd );
+    shutdown( sockfd, 1 );
+    waitpid( pid, NULL, 0 );
+    exit( 0 );
+  }
+
+  if ( argc - optind < 1 ) {
+    die( usage_format, argv[0] );
+  }
+
+  string userhost = argv[optind++];
+  char **command = &argv[optind];
+  int commands = argc - optind;
+
+  string color_invocation = client + " -c";
+  FILE *color_file = popen( color_invocation.c_str(), "r" );
+  if ( !color_file ) {
+    die( "%s: popen: %d", argv[0], errno );
+  }
+  char *buf = NULL;
+  size_t buf_sz = 0;
+  ssize_t n;
+  if ( ( n = getline( &buf, &buf_sz, color_file ) ) < 0 ) {
+    die( "%s: Can't count colors: %d", argv[0], errno );
+  }
+  string colors = string( buf, n );
+  pclose( color_file );
+
+  if ( !colors.size() ||
+       colors.find_first_not_of( "0123456789" ) != string::npos ||
+       atoi( colors.c_str() ) < 0 ) {
+    colors = "0";
+  }
+
+  int pty, pty_slave;
+  struct winsize ws;
+  if ( ioctl( 0, TIOCGWINSZ, &ws ) == -1 ) {
+    die( "%s: ioctl: %d", argv[0], errno );
+  }
+
+  if ( openpty( &pty, &pty_slave, NULL, NULL, &ws ) == -1 ) {
+    die( "%s: openpty: %d", argv[0], errno );
+  }
+
+  int pid = fork();
+  if ( pid == -1 ) {
+    die( "%s: fork: %d", argv[0], errno );
+  }
+  if ( pid == 0 ) {
+    close( pty );
+    if ( -1 == dup2( pty_slave, 1 ) ||
+         -1 == dup2( pty_slave, 2 ) ) {
+      die( "%s: dup2: %d", argv[0], errno );
+    }
+    close( pty_slave );
+
+    vector<string> server_args;
+    server_args.push_back( "new" );
+    server_args.push_back( "-s" );
+    server_args.push_back( "-c" );
+    server_args.push_back( colors );
+    if ( port_request.size() ) {
+      server_args.push_back( "-p" );
+      server_args.push_back( port_request );
+    }
+    if ( commands ) {
+      server_args.insert( server_args.end(), command, command + commands );
+    }
+    string quoted_self = shell_quote_string( string( argv[0] ) );
+    string quoted_server_args = shell_quote( server_args );
+    fflush( stdout );
+
+    string proxy_arg = "ProxyCommand=" + quoted_self + " --fake-proxy -- %h %p";
+    string ssh_remote_command = server + " " + quoted_server_args;
+
+    vector<string> ssh_args;
+    ssh_args.push_back( "-S" );
+    ssh_args.push_back( "none" );
+    ssh_args.push_back( "-o" );
+    ssh_args.push_back( proxy_arg );
+    ssh_args.push_back( "-t" );
+    ssh_args.push_back( userhost );
+    if ( ssh_port.size() ) {
+      ssh_args.push_back( "-p" );
+      ssh_args.push_back( ssh_port );
+    }
+    ssh_args.push_back( "--" );
+    ssh_args.push_back( ssh_remote_command );
+
+    string ssh_exec_string = ssh + " " + shell_quote( ssh_args );
+
+    int ret = execlp( "sh", "sh", "-c", ssh_exec_string.c_str(), (char *)NULL );
+    if ( ret == -1 ) {
+      die( "Cannot exec ssh: %d", errno );
+    }
+  }
+
+  close( pty_slave );
+  string ip, port, key;
+
+  FILE *pty_file = fdopen( pty, "r" );
+  string line;
+  while ( ( n = getline( &buf, &buf_sz, pty_file ) ) >= 0 ) {
+    line = string( buf, n );
+    line = line.erase( line.find_last_not_of( "\n" ) );
+    if ( line.compare( 0, 8, "MOSH IP " ) == 0 ) {
+      size_t ip_end = line.find_last_not_of( " \t\n\r" );
+      if ( ip_end != string::npos && ip_end >= 8 ) {
+        ip = line.substr( 8, ip_end + 1 - 8 );
+      }
+    } else if ( line.compare( 0, 13, "MOSH CONNECT " ) == 0 ) {
+      size_t port_end = line.find_first_not_of( "0123456789", 13 );
+      if ( port_end != string::npos && port_end >= 13 ) {
+        port = line.substr( 13, port_end - 13 );
+      }
+      string rest = line.substr( port_end + 1 );
+      size_t key_end = rest.find_last_not_of( " \t\n\r" );
+      size_t key_valid_end = rest.find_last_of( key_valid_char_set );
+      if ( key_valid_end == key_end && key_end + 1 == 22 ) {
+        key = rest.substr( 0, key_end + 1 );
+      }
+      break;
+    } else {
+      printf( "%s\n", line.c_str() );
+    }
+  }
+  waitpid( pid, NULL, 0 );
+
+  if ( !ip.size() ) {
+    die( "%s: Did not find remote IP address (is SSH ProxyCommand disabled?).",
+         argv[0] );
+  }
+
+  if ( !key.size() || !port.size() ) {
+    die( "%s: Did not find mosh server startup message.", argv[0] );
+  }
+
+  setenv( "MOSH_KEY", key.c_str(), 1 );
+  setenv( "MOSH_PREDICTION_DISPLAY", predict.c_str(), 1 );
+  execlp( client.c_str(), client.c_str(), ip.c_str(), port.c_str(), (char *)NULL );
+}