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termux-packages/packages/mosh/mosh.cc

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// 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 <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>
#include <pty.h>
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=COMMAND 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"
"-6 use IPv6 only\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"
" --no-init do not send terminal initialization string\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, term_init=1;
int force_ipv6 = 0;
static struct option long_options[] =
{
{ "client", required_argument, 0, 'c' },
{ "server", required_argument, 0, 's' },
{ "no-init", no_argument, &term_init, 0 },
{ "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, "6anp: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;
case '6':
force_ipv6 = true;
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 (force_ipv6) {
hints.ai_family = AF_INET6;
}
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;
if (force_ipv6) {
try_family = AF_INET6;
}
// 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 ) {
close( STDIN_FILENO );
cat( sockfd, STDOUT_FILENO );
shutdown( sockfd, 0 );
exit( 0 );
}
signal( SIGHUP, SIG_IGN );
close( STDOUT_FILENO );
cat( STDIN_FILENO, sockfd );
shutdown( sockfd, SHUT_WR /* = 1 */ );
close( STDIN_FILENO );
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;
char *buf = NULL;
size_t buf_sz = 0;
ssize_t n;
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( "-c" );
server_args.push_back( "256" );
server_args.push_back( "-s" );
if ( port_request.size() ) {
server_args.push_back( "-p" );
server_args.push_back( port_request );
}
for (char const* env_name : {
"LANG", "LANGUAGE", "LC_CTYPE", "LC_NUMERIC",
"LC_TIME", "LC_COLLATE", "LC_MONETARY", "LC_MESSAGES", "LC_PAPER",
"LC_NAME", "LC_ADDRESS", "LC_TELEPHONE", "LC_MEASUREMENT",
"LC_IDENTIFICATION", "LC_ALL" }) {
char* env_value = getenv(env_name);
if (env_value) {
server_args.push_back("-l");
server_args.push_back(string(env_name) + "=" + env_value);
}
}
if ( commands ) {
server_args.push_back( "--" );
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;
if (force_ipv6) {
proxy_arg += " -6";
}
proxy_arg += " --fake-proxy -- %h %p";
string ssh_remote_command = server + " " + quoted_server_args;
vector<string> ssh_args;
ssh_args.push_back( "-n" );
ssh_args.push_back( "-tt" );
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( userhost );
if ( ssh_port.size() ) {
ssh_args.push_back( "-p" );
ssh_args.push_back( ssh_port );
}
if ( force_ipv6 ) {
ssh_args.push_back( "-6" );
}
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 );
if (!term_init) setenv( "MOSH_NO_TERM_INIT", "1", 1 );
execlp( client.c_str(), client.c_str(), ip.c_str(), port.c_str(), (char *)NULL );
}
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