Currently, an outbound socket connection (client) can be created using the syntax:
exec 5<> /dev/tcp/HOST/PORT This patch implements support for accepting incoming connections (server) using a slightly different syntax: exec 6<> /dev/tcp/HOST/:PORT # note the colon The listen/accept call will block until a connection is received and it will be bound to the redirection. Included in the patch is a small test that has an example of usage. I've also attach a minimal web server that leverages this functionality (pure bash except for a call to wc and cat). Please include me in Cc since I am not on the list. Thanks, Joel Martin (kanaka)
From 04df5a7a23325a7e9b42ee3d4b306fa222326d99 Mon Sep 17 00:00:00 2001
From: Joel Martin <git...@martintribe.org>
Date: Tue, 12 Nov 2013 15:30:47 -0500
Subject: [PATCH] Listening socket support via /dev/tcp/HOST/:PORT
In addition to the ability to create normal outgoing socket
connections (/dev/tcp/HOST/PORT) this adds the ability to create
a listen socket connection. The creation of the listener will block
until a new connection is created via the listener.
Signed-off-by: Joel Martin <git...@martintribe.org>
---
lib/sh/netopen.c | 110 +++++++++++++++++++++++++++++++----------
tests/misc/dev-tcp-serv.tests | 44 +++++++++++++++++
2 files changed, 127 insertions(+), 27 deletions(-)
create mode 100644 tests/misc/dev-tcp-serv.tests
diff --git a/lib/sh/netopen.c b/lib/sh/netopen.c
index 736d413..0a2a9f1 100644
--- a/lib/sh/netopen.c
+++ b/lib/sh/netopen.c
@@ -69,9 +69,9 @@ extern int inet_aton __P((const char *, struct in_addr *));
#ifndef HAVE_GETADDRINFO
static int _getaddr __P((char *, struct in_addr *));
static int _getserv __P((char *, int, unsigned short *));
-static int _netopen4 __P((char *, char *, int));
+static int _netopen4 __P((char *, char *, int, int));
#else /* HAVE_GETADDRINFO */
-static int _netopen6 __P((char *, char *, int));
+static int _netopen6 __P((char *, char *, int, int));
#endif
static int _netopen __P((char *, char *, int));
@@ -154,14 +154,16 @@ _getserv (serv, proto, pp)
* traditional BSD mechanisms. Returns the connected socket or -1 on error.
*/
static int
-_netopen4(host, serv, typ)
+_netopen4(host, serv, typ, listener)
char *host, *serv;
- int typ;
+ int typ, listener;
{
struct in_addr ina;
struct sockaddr_in sin;
unsigned short p;
- int s, e;
+ int optval = 1;
+ int s, c, e;
+ const char *step;
if (_getaddr(host, &ina) == 0)
{
@@ -189,16 +191,39 @@ _netopen4(host, serv, typ)
return (-1);
}
- if (connect (s, (struct sockaddr *)&sin, sizeof (sin)) < 0)
+ if (!listener)
+ {
+ step = "connect";
+ if (connect (s, (struct sockaddr *)&sin, sizeof (sin)) < 0)
+ goto cleanup;
+ }
+ else
{
- e = errno;
- sys_error("connect");
+ //internal_error("Listening (4) on: %s:%s %c\n", host, serv, typ);
+ step = "setsockopt";
+ if (setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &optval, sizeof optval) <0)
+ goto cleanup;
+ step = "bind";
+ if (bind(s, (struct sockaddr*)&sin, sizeof(sin)) < 0)
+ goto cleanup;
+ step = "listen";
+ if (listen(s, 1) < 0)
+ goto cleanup;
+ step = "accept";
+ if ((c = accept(s, (struct sockaddr*)NULL, NULL)) < 0)
+ goto cleanup;
close(s);
- errno = e;
- return (-1);
+ s = c;
}
return(s);
+
+ cleanup:
+ e = errno;
+ sys_error(step);
+ close(s);
+ errno = e;
+ return (-1);
}
#endif /* ! HAVE_GETADDRINFO */
@@ -209,13 +234,15 @@ _netopen4(host, serv, typ)
* on error.
*/
static int
-_netopen6 (host, serv, typ)
+_netopen6 (host, serv, typ, listener)
char *host, *serv;
- int typ;
+ int typ, listener;
{
- int s, e;
+ int s, c, e;
struct addrinfo hints, *res, *res0;
+ int optval = 1;
int gerr;
+ const char *step;
memset ((char *)&hints, 0, sizeof (hints));
/* XXX -- if problems with IPv6, set to PF_INET for IPv4 only */
@@ -247,22 +274,45 @@ _netopen6 (host, serv, typ)
freeaddrinfo (res0);
return -1;
}
- if (connect (s, res->ai_addr, res->ai_addrlen) < 0)
+ if (!listener)
{
- if (res->ai_next)
- {
- close (s);
- continue;
- }
- e = errno;
- sys_error ("connect");
- close (s);
- freeaddrinfo (res0);
- errno = e;
- return -1;
+ step = "connect";
+ if (connect (s, res->ai_addr, res->ai_addrlen) < 0)
+ goto cleanup;
+ }
+ else
+ {
+ //internal_error("Listening 6 on: %s:%s %c\n", host, serv, typ);
+ step = "setsockopt";
+ if (setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &optval, sizeof optval) < 0)
+ goto cleanup;
+ step = "bind";
+ if (bind(s, res->ai_addr, res->ai_addrlen) < 0)
+ goto cleanup;
+ step = "listen";
+ if (listen(s, 1) < 0)
+ goto cleanup;
+ step = "accept";
+ if ((c = accept(s, (struct sockaddr*)NULL, NULL)) < 0)
+ goto cleanup;
+ close(s);
+ s = c;
}
freeaddrinfo (res0);
break;
+
+ cleanup:
+ if (res->ai_next)
+ {
+ close (s);
+ continue;
+ }
+ e = errno;
+ sys_error (step);
+ close (s);
+ freeaddrinfo (res0);
+ errno = e;
+ return -1;
}
return s;
}
@@ -278,10 +328,16 @@ _netopen(host, serv, typ)
char *host, *serv;
int typ;
{
+ int listener = 0;
+ if (serv[0] == ':') {
+ listener = 1;
+ serv++;
+ }
+
#ifdef HAVE_GETADDRINFO
- return (_netopen6 (host, serv, typ));
+ return (_netopen6 (host, serv, typ, listener));
#else
- return (_netopen4 (host, serv, typ));
+ return (_netopen4 (host, serv, typ, listener));
#endif
}
diff --git a/tests/misc/dev-tcp-serv.tests b/tests/misc/dev-tcp-serv.tests
new file mode 100644
index 0000000..53a89a7
--- /dev/null
+++ b/tests/misc/dev-tcp-serv.tests
@@ -0,0 +1,44 @@
+#!/bin/bash
+
+# Start a background server
+(
+CNT=0
+while true; do
+ exec 9<> /dev/tcp/127.0.0.1/:13567 || break
+ echo "CNT: $CNT" >&9
+ CNT=$(( CNT + 1 ))
+ exec 9>&- # close it
+done
+) &
+
+spid=$!
+
+# cleanup the background server on exit
+cleanup() {
+ kill $spid
+}
+trap "cleanup" TERM QUIT INT EXIT
+
+# Wait for the server to startup
+sleep 1
+
+# Connect to the server and get the first response
+exec 10<> /dev/tcp/127.0.0.1/13567
+read -u 10 -r LINE
+exec 10>&-
+echo "Got server response: $LINE"
+if [ "${LINE}" != "CNT: 0" ]; then
+ echo "Expected: CNT: 0"
+ exit 1
+fi
+
+# Connect to the server and get the second response
+exec 10<> /dev/tcp/127.0.0.1/13568
+read -u 10 -r LINE
+echo "Got server response: $LINE"
+if [ "${LINE}" != "CNT: 1" ]; then
+ echo "Expected: CNT: 1"
+ exit 1
+fi
+
+exit 0
--
1.7.9.5
www.sh
Description: Bourne shell script
