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/* accept - listen for and accept a remote network connection on a given port */
/*
Copyright (C) 2020 Free Software Foundation, Inc.
This file is part of GNU Bash.
Bash 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.
Bash 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 Bash. If not, see <http://www.gnu.org/licenses/>.
*/
#include <config.h>
#if defined (HAVE_UNISTD_H)
# include <unistd.h>
#endif
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include "bashtypes.h"
#include <errno.h>
#include <time.h>
#include <limits.h>
#include "typemax.h"
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include "loadables.h"
static int accept_bind_variable (char *, int);
int
accept_builtin (list)
WORD_LIST *list;
{
SHELL_VAR *v;
intmax_t iport;
int opt;
char *tmoutarg, *fdvar, *rhostvar, *rhost, *bindaddr;
unsigned short uport;
int servsock, clisock;
struct sockaddr_in server, client;
socklen_t clientlen;
struct timeval timeval;
struct linger linger = { 0, 0 };
rhostvar = tmoutarg = fdvar = rhost = bindaddr = (char *)NULL;
reset_internal_getopt ();
while ((opt = internal_getopt (list, "b:r:t:v:")) != -1)
{
switch (opt)
{
case 'b':
bindaddr = list_optarg;
break;
case 'r':
rhostvar = list_optarg;
break;
case 't':
tmoutarg = list_optarg;
break;
case 'v':
fdvar = list_optarg;
break;
CASE_HELPOPT;
default:
builtin_usage ();
return (EX_USAGE);
}
}
list = loptend;
/* Validate input and variables */
if (tmoutarg)
{
long ival, uval;
opt = uconvert (tmoutarg, &ival, &uval, (char **)0);
if (opt == 0 || ival < 0 || uval < 0)
{
builtin_error ("%s: invalid timeout specification", tmoutarg);
return (EXECUTION_FAILURE);
}
timeval.tv_sec = ival;
timeval.tv_usec = uval;
/* XXX - should we warn if ival == uval == 0 ? */
}
if (list == 0)
{
builtin_usage ();
return (EX_USAGE);
}
if (legal_number (list->word->word, &iport) == 0 || iport < 0 || iport > TYPE_MAXIMUM (unsigned short))
{
builtin_error ("%s: invalid port number", list->word->word);
return (EXECUTION_FAILURE);
}
uport = (unsigned short)iport;
if (fdvar == 0)
fdvar = "ACCEPT_FD";
unbind_variable (fdvar);
if (rhostvar)
unbind_variable (rhostvar);
if ((servsock = socket (AF_INET, SOCK_STREAM, IPPROTO_IP)) < 0)
{
builtin_error ("cannot create socket: %s", strerror (errno));
return (EXECUTION_FAILURE);
}
memset ((char *)&server, 0, sizeof (server));
server.sin_family = AF_INET;
server.sin_port = htons(uport);
server.sin_addr.s_addr = bindaddr ? inet_addr (bindaddr) : htonl(INADDR_ANY);
if (server.sin_addr.s_addr == INADDR_NONE)
{
builtin_error ("invalid address: %s", strerror (errno));
return (EXECUTION_FAILURE);
}
opt = 1;
setsockopt (servsock, SOL_SOCKET, SO_REUSEADDR, (void *)&opt, sizeof (opt));
setsockopt (servsock, SOL_SOCKET, SO_LINGER, (void *)&linger, sizeof (linger));
if (bind (servsock, (struct sockaddr *)&server, sizeof (server)) < 0)
{
builtin_error ("socket bind failure: %s", strerror (errno));
close (servsock);
return (EXECUTION_FAILURE);
}
if (listen (servsock, 1) < 0)
{
builtin_error ("listen failure: %s", strerror (errno));
close (servsock);
return (EXECUTION_FAILURE);
}
if (tmoutarg)
{
fd_set iofds;
FD_ZERO(&iofds);
FD_SET(servsock, &iofds);
opt = select (servsock+1, &iofds, 0, 0, &timeval);
if (opt < 0)
builtin_error ("select failure: %s", strerror (errno));
if (opt <= 0)
{
close (servsock);
return (EXECUTION_FAILURE);
}
}
clientlen = sizeof (client);
if ((clisock = accept (servsock, (struct sockaddr *)&client, &clientlen)) < 0)
{
builtin_error ("client accept failure: %s", strerror (errno));
close (servsock);
return (EXECUTION_FAILURE);
}
close (servsock);
accept_bind_variable (fdvar, clisock);
if (rhostvar)
{
rhost = inet_ntoa (client.sin_addr);
v = builtin_bind_variable (rhostvar, rhost, 0);
if (v == 0 || readonly_p (v) || noassign_p (v))
builtin_error ("%s: cannot set variable", rhostvar);
}
return (EXECUTION_SUCCESS);
}
static int
accept_bind_variable (varname, intval)
char *varname;
int intval;
{
SHELL_VAR *v;
char ibuf[INT_STRLEN_BOUND (int) + 1], *p;
p = fmtulong (intval, 10, ibuf, sizeof (ibuf), 0);
v = builtin_bind_variable (varname, p, 0); /* XXX */
if (v == 0 || readonly_p (v) || noassign_p (v))
builtin_error ("%s: cannot set variable", varname);
return (v != 0);
}
char *accept_doc[] = {
"Accept a network connection on a specified port.",
""
"This builtin allows a bash script to act as a TCP/IP server.",
"",
"Options, if supplied, have the following meanings:",
" -b address use ADDRESS as the IP address to listen on; the",
" default is INADDR_ANY",
" -t timeout wait TIMEOUT seconds for a connection. TIMEOUT may",
" be a decimal number including a fractional portion",
" -v varname store the numeric file descriptor of the connected",
" socket into VARNAME. The default VARNAME is ACCEPT_FD",
" -r rhost store the IP address of the remote host into the shell",
" variable RHOST, in dotted-decimal notation",
"",
"If successful, the shell variable ACCEPT_FD, or the variable named by the",
"-v option, will be set to the fd of the connected socket, suitable for",
"use as 'read -u$ACCEPT_FD'. RHOST, if supplied, will hold the IP address",
"of the remote client. The return status is 0.",
"",
"On failure, the return status is 1 and ACCEPT_FD (or VARNAME) and RHOST,",
"if supplied, will be unset.",
"",
"The server socket fd will be closed before accept returns.",
(char *) NULL
};
struct builtin accept_struct = {
"accept", /* builtin name */
accept_builtin, /* function implementing the builtin */
BUILTIN_ENABLED, /* initial flags for builtin */
accept_doc, /* array of long documentation strings. */
"accept [-b address] [-t timeout] [-v varname] [-r addrvar ] port", /* usage synopsis; becomes short_doc */
0 /* reserved for internal use */
};
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