server: support binding to arbitrary interfaces

Some installations of OpenOCD are used in restricted environments that
do not permit binding to public interfaces.

This patch does not affect the default behavior to listen on all
interfaces, however it does give the option to restrict services by way
of the bindto command.

Change-Id: Id51bd64b376a8c62dd47b08b4d834872925e6af2
Signed-off-by: Steven Stallion <stallion@squareup.com>
Reviewed-on: http://openocd.zylin.com/3534
Tested-by: jenkins
Reviewed-by: Tomas Vanek <vanekt@fbl.cz>

2 files changed, 49 insertions, 2 deletions

diff --git a/doc/openocd.texi b/doc/openocd.texi
index 94f1f315..1d517213 100644
--- a/doc/openocd.texi
+++ b/doc/openocd.texi
@@ -6731,6 +6731,11 @@ the initial log output channel is stderr.
 Add @var{directory} to the file/script search path.
 @end deffn
 
+@deffn Command bindto [name]
+Specify address by name on which to listen for incoming TCP/IP connections.
+By default, OpenOCD will listen on all available interfaces.
+@end deffn
+
 @anchor{targetstatehandling}
 @section Target State handling
 @cindex reset
diff --git a/src/server/server.c b/src/server/server.c
index cdb62851..f6889a01 100644
--- a/src/server/server.c
+++ b/src/server/server.c
@@ -36,6 +36,10 @@
 
 #include <signal.h>
 
+#ifdef HAVE_NETDB_H
+#include <netdb.h>
+#endif
+
 #ifndef _WIN32
 #include <netinet/tcp.h>
 #endif
@@ -52,6 +56,9 @@ static int last_signal;
 /* set the polling period to 100ms */
 static int polling_period = 100;
 
+/* address by name on which to listen for incoming TCP/IP connections */
+static char *bindto_name;
+
 static int add_connection(struct service *service, struct command_context *cmd_ctx)
 {
 	socklen_t address_size;
@@ -194,6 +201,7 @@ int add_service(char *name,
 	void *priv)
 {
 	struct service *c, **p;
+	struct hostent *hp;
 	int so_reuseaddr_option = 1;
 
 	c = malloc(sizeof(struct service));
@@ -240,11 +248,21 @@ int add_service(char *name,
 
 		memset(&c->sin, 0, sizeof(c->sin));
 		c->sin.sin_family = AF_INET;
-		c->sin.sin_addr.s_addr = INADDR_ANY;
+
+		if (bindto_name == NULL)
+			c->sin.sin_addr.s_addr = INADDR_ANY;
+		else {
+			hp = gethostbyname(bindto_name);
+			if (hp == NULL) {
+				LOG_ERROR("couldn't resolve bindto address: %s", bindto_name);
+				exit(-1);
+			}
+			memcpy(&c->sin.sin_addr, hp->h_addr_list[0], hp->h_length);
+		}
 		c->sin.sin_port = htons(c->portnumber);
 
 		if (bind(c->fd, (struct sockaddr *)&c->sin, sizeof(c->sin)) == -1) {
-			LOG_ERROR("couldn't bind to socket: %s", strerror(errno));
+			LOG_ERROR("couldn't bind %s to socket: %s", name, strerror(errno));
 			exit(-1);
 		}
 
@@ -632,6 +650,22 @@ COMMAND_HANDLER(handle_poll_period_command)
 	return ERROR_OK;
 }
 
+COMMAND_HANDLER(handle_bindto_command)
+{
+	switch (CMD_ARGC) {
+		case 0:
+			command_print(CMD_CTX, "bindto name: %s", bindto_name);
+			break;
+		case 1:
+			free(bindto_name);
+			bindto_name = strdup(CMD_ARGV[0]);
+			break;
+		default:
+			return ERROR_COMMAND_SYNTAX_ERROR;
+	}
+	return ERROR_OK;
+}
+
 static const struct command_registration server_command_handlers[] = {
 	{
 		.name = "shutdown",
@@ -647,6 +681,14 @@ static const struct command_registration server_command_handlers[] = {
 		.usage = "",
 		.help = "set the servers polling period",
 	},
+	{
+		.name = "bindto",
+		.handler = &handle_bindto_command,
+		.mode = COMMAND_ANY,
+		.usage = "[name]",
+		.help = "Specify address by name on which to listen for "
+		    "incoming TCP/IP connections",
+	},
 	COMMAND_REGISTRATION_DONE
 };