From b52da1045e968f75a54aee80809add41bf99518b Mon Sep 17 00:00:00 2001
From: Johannes Schlatow <schlatow@ida.ing.tu-bs.de>
Date: Tue, 25 Mar 2014 15:30:36 +0100
Subject: [PATCH] nic_drv: read MAC and tap device from config

E.g.:
<nic mac="12:23:34:45:56:67" tap="tap1"/>

Fixes #1165.
---
 repos/os/src/drivers/nic/linux/main.cc   | 51 +++++++++++++++++++-----
 repos/os/src/drivers/nic/linux/target.mk |  2 +-
 2 files changed, 42 insertions(+), 11 deletions(-)

diff --git a/repos/os/src/drivers/nic/linux/main.cc b/repos/os/src/drivers/nic/linux/main.cc
index a6bffbe78..3e650996a 100644
--- a/repos/os/src/drivers/nic/linux/main.cc
+++ b/repos/os/src/drivers/nic/linux/main.cc
@@ -4,11 +4,15 @@
  * \author Christian Helmuth
  * \date   2011-08-08
  *
- * Currently, we connect to tap0 only. Possbile candidates for configuration
- * options are:
+ * Configuration options are:
  *
  * - TAP device to connect to (default is tap0)
  * - MAC address (default is 02-00-00-00-00-01)
+ *
+ * These can be set in the config section as follows:
+ *  <config>
+ *  	<nic mac="12:23:34:45:56:67" tap="tap1"/>
+ *  </config>
  */
 
 /*
@@ -22,6 +26,8 @@
 #include <base/sleep.h>
 #include <cap_session/connection.h>
 #include <nic/component.h>
+#include <os/config.h>
+#include <nic/xml_node.h>
 
 /* Linux */
 #include <unistd.h>
@@ -79,9 +85,21 @@ class Linux_driver : public Nic::Driver
 				/* this error is fatal */
 				throw Genode::Exception();
 			}
+
 			Genode::memset(&ifr, 0, sizeof(ifr));
 			ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
-			Genode::strncpy(ifr.ifr_name, "tap0", sizeof(ifr.ifr_name));
+
+			/* get tap device from config */
+			try {
+				Genode::Xml_node nic_node = Genode::config()->xml_node().sub_node("nic");
+				nic_node.attribute("tap").value(ifr.ifr_name, sizeof(ifr.ifr_name));
+				PINF("Using tap device \"%s\"", ifr.ifr_name);
+			} catch (...) {
+				/* use tap0 if no config has been provided */
+				Genode::strncpy(ifr.ifr_name, "tap0", sizeof(ifr.ifr_name));
+				PINF("No config provided, using tap0");
+			}
+
 			ret = ioctl(fd, TUNSETIFF, (void *) &ifr);
 			if (ret != 0) {
 				PERR("could not configure /dev/net/tun: no virtual network emulation");
@@ -98,13 +116,26 @@ class Linux_driver : public Nic::Driver
 		Linux_driver(Nic::Rx_buffer_alloc &alloc)
 		: _alloc(alloc), _tap_fd(_setup_tap_fd()), _rx_thread(_tap_fd, *this)
 		{
-			/* fake MAC address (unicast, locally managed) */
-			_mac_addr.addr[0] = 0x02;
-			_mac_addr.addr[1] = 0x00;
-			_mac_addr.addr[2] = 0x00;
-			_mac_addr.addr[3] = 0x00;
-			_mac_addr.addr[4] = 0x00;
-			_mac_addr.addr[5] = 0x01;
+			/* try using configured MAC address */
+			try {
+				Genode::Xml_node nic_config = Genode::config()->xml_node().sub_node("nic");
+				nic_config.attribute("mac").value(&_mac_addr);
+				PINF("Using configured MAC address \"%02x:%02x:%02x:%02x:%02x:%02x\"",
+						_mac_addr.addr[0],
+						_mac_addr.addr[1],
+						_mac_addr.addr[2],
+						_mac_addr.addr[3],
+						_mac_addr.addr[4],
+						_mac_addr.addr[5]	);
+			} catch (...) {
+				/* fall back to fake MAC address (unicast, locally managed) */
+				_mac_addr.addr[0] = 0x02;
+				_mac_addr.addr[1] = 0x00;
+				_mac_addr.addr[2] = 0x00;
+				_mac_addr.addr[3] = 0x00;
+				_mac_addr.addr[4] = 0x00;
+				_mac_addr.addr[5] = 0x01;
+			}
 
 			_rx_thread.start();
 		}
diff --git a/repos/os/src/drivers/nic/linux/target.mk b/repos/os/src/drivers/nic/linux/target.mk
index 3fa319750..953ce5e00 100644
--- a/repos/os/src/drivers/nic/linux/target.mk
+++ b/repos/os/src/drivers/nic/linux/target.mk
@@ -1,4 +1,4 @@
 TARGET   = nic_drv
 REQUIRES = linux
-LIBS     = lx_hybrid
+LIBS     = lx_hybrid config
 SRC_CC   = main.cc