Make nic_bridge's MAC address range configurable

By adding a "mac=XX:XX:XX:XX:XX:XX" attribute/value pair to the nic_bridge's
configuration one can define the first MAC address from which the nic_brigde
will allocate MACs for it's clients. Note: that the least relevant byte will
be ignored, and ranges from 0-255. Fixes #424.

dde_linux/src/drivers/usb/nic/nic.cc

@@ -16,6 +16,7 @@
 #include <nic_session/nic_session.h>
 #include <cap_session/connection.h>
 #include <os/config.h>
+#include <nic/xml_node.h>
 #include <util/xml_node.h>
 
 #include <lx_emul.h>
@@ -567,39 +568,6 @@ struct sk_buff *skb_dequeue(struct sk_buff_head *list)
  ** linux/inerrupt.h **
  **********************/
 
-namespace Genode {
-
-	/**
-	 * Convert ASCII string to mac address
-	 */
-	template <>
-	inline size_t ascii_to<Nic::Mac_address>(char const *s, Nic::Mac_address* mac, unsigned)
-	{
-		enum { 
-			HEX     = true,
-		};
-	
-		if(strlen(s) < MAC_LEN)
-			throw -1;
-	
-		char mac_str[6];
-		for (int i = 0; i < ETH_ALEN; i++) {
-			int hi = i * 3;
-			int lo = hi + 1;
-	
-			if (!is_digit(s[hi], HEX) || !is_digit(s[lo], HEX))
-				throw -1;
-	
-			mac_str[i] = (digit(s[hi], HEX) << 4) | digit(s[lo], HEX);
-		}
-	
-		Genode::memcpy(mac->addr, mac_str, ETH_ALEN);
-	
-		return MAC_LEN;
-	}
-}
-
-
 static void snprint_mac(char *buf, char *mac)
 {
 	for (int i = 0; i < ETH_ALEN; i++)

os/include/nic/xml_node.h

@@ -0,0 +1,56 @@
+/*
+ * \brief  Xml-node routines used internally in NIC drivers
+ * \author Sebastian Sumpf
+ * \author Stefan Kalkowski
+ * \date   2012-10-22
+ */
+
+/*
+ * Copyright (C) 2012 Genode Labs GmbH
+ *
+ * This file is part of the Genode OS framework, which is distributed
+ * under the terms of the GNU General Public License version 2.
+ */
+
+#ifndef _INCLUDE__NIC__XML_NODE_H_
+#define _INCLUDE__NIC__XML_NODE_H_
+
+#include <nic_session/nic_session.h>
+#include <util/string.h>
+
+namespace Genode {
+
+	/**
+	 * Convert ASCII string to mac address
+	 */
+	template <>
+	inline size_t ascii_to<Nic::Mac_address>(char const *s,
+	                                         Nic::Mac_address* mac, unsigned)
+	{
+		enum {
+			HEX          = true,
+			MAC_CHAR_LEN = 17,   /* 12 number and 6 colons */
+			MAC_SIZE     = 6,
+		};
+
+		if(strlen(s) < MAC_CHAR_LEN)
+			throw -1;
+
+		char mac_str[6];
+		for (int i = 0; i < MAC_SIZE; i++) {
+			int hi = i * 3;
+			int lo = hi + 1;
+
+			if (!is_digit(s[hi], HEX) || !is_digit(s[lo], HEX))
+				throw -1;
+
+			mac_str[i] = (digit(s[hi], HEX) << 4) | digit(s[lo], HEX);
+		}
+
+		Genode::memcpy(mac->addr, mac_str, MAC_SIZE);
+
+		return MAC_CHAR_LEN;
+	}
+}
+
+#endif /* _INCLUDE__NIC__XML_NODE_H_ */

os/src/server/nic_bridge/README

@@ -0,0 +1,17 @@
+The nic_bridge provides multiple sessions of the 'Nic' service while
+using a single 'Nic' session for forwarding requests. For proper working
+it implements some kind of the 'proxy arp' protocol (rfc1027). That
+means it allocates a MAC address for each client. Whenever a client
+sends a packet it changes the sender MAC address to the one it hold
+available for the client. Moreover, it monitors DHCP packets, and
+tracks which IP address is used by which client. Whenever ARP packets
+come from the outside it will answer them with the corresponding MAC
+address.
+
+By adding the following attribute to the 'nic_bridge' config node:
+
+! <config mac="02:02:02:02:02:00"/>
+
+one can define the first MAC address from which the nic_brigde
+will allocate MACs for it's clients. Note: that the least relevant
+byte will be ignored always starting from 0.

os/src/server/nic_bridge/mac.cc

@@ -18,4 +18,4 @@
  * it's likely, that we will have no clashes here.
  * (e.g. Linux uses 02:00... for its tap-devices.)
  */
-const Net::Ethernet_frame::Mac_address Net::Mac_allocator::_mac_addr_base(0x02);
+Net::Ethernet_frame::Mac_address Net::Mac_allocator::mac_addr_base(0x02);

os/src/server/nic_bridge/mac.h

@@ -28,9 +28,6 @@ namespace Net {
 	{
 		private:
 
-			/* reference MAC address */
-			static const Ethernet_frame::Mac_address _mac_addr_base;
-
 			/* limit available MAC addresses to one byte range */
 			enum { MSB_MAX = 0xFF };
 
@@ -47,6 +44,9 @@ namespace Net {
 			class Alloc_failed : Genode::Exception {};
 
 
+			/* reference MAC address */
+			static Ethernet_frame::Mac_address mac_addr_base;
+
 			Mac_allocator() { Genode::memset(&_msbs, 0, sizeof(_msbs)); }
 
 
@@ -61,7 +61,7 @@ namespace Net {
 				for (int i=0; i < MSB_MAX; i++) {
 					if (!_msbs[i].used) {
 						_msbs[i].used = 1;
-						Ethernet_frame::Mac_address mac = _mac_addr_base;
+						Ethernet_frame::Mac_address mac = mac_addr_base;
 						mac.addr[5] = i;
 						return mac;
 					}

os/src/server/nic_bridge/main.cc

@@ -17,6 +17,8 @@
 #include <cap_session/connection.h>
 #include <nic_session/connection.h>
 #include <nic/packet_allocator.h>
+#include <nic/xml_node.h>
+#include <os/config.h>
 
 #include "packet_handler.h"
 #include "component.h"
@@ -38,6 +40,14 @@ int main(int, char **)
 		TX_BUF_SIZE = Nic::Session::TX_QUEUE_SIZE * PACKET_SIZE
 	};
 
+	/* read MAC address prefix from config file */
+	try {
+		Nic::Mac_address mac;
+		Genode::config()->xml_node().attribute("mac").value(&mac);
+		Genode::memcpy(&Net::Mac_allocator::mac_addr_base, &mac,
+		               sizeof(Net::Mac_allocator::mac_addr_base));
+	} catch(...) {}
+
 	Root_capability nic_root_cap;
 	try {
 		static Nic::Connection nic(&tx_block_alloc, TX_BUF_SIZE, RX_BUF_SIZE);