[Lguest] [PATCH 3/3] lguest: Support assigning a MAC address
Mark McLoughlin
markmc at redhat.com
Fri Jun 13 23:05:00 EST 2008
If you've got a nice DHCP configuration which maps MAC
addresses to specific IP addresses, then you're going to
want to start your guest with one of those MAC addresses.
Also, in Fedora, we have persistent network interface naming
based on the MAC address, so with randomly assigned
addresses you're soon going to hit eth13. Who knows what
will happen then!
Allow assigning a MAC address to the network interface with
e.g.
--tunnet=bridge:eth0:00:FF:95:6B:DA:3D
or:
--tunnet=192.168.121.1:00:FF:95:6B:DA:3D
which is pretty unintelligable, but ...
Signed-off-by: Mark McLoughlin <markmc at redhat.com>
---
Documentation/lguest/lguest.c | 92 ++++++++++++++++++++++++++++-------------
1 files changed, 63 insertions(+), 29 deletions(-)
diff --git a/Documentation/lguest/lguest.c b/Documentation/lguest/lguest.c
index 40bec7e..0c4d75d 100644
--- a/Documentation/lguest/lguest.c
+++ b/Documentation/lguest/lguest.c
@@ -1273,6 +1273,19 @@ static u32 str2ip(const char *ipaddr)
return (byte[0] << 24) | (byte[1] << 16) | (byte[2] << 8) | byte[3];
}
+static void str2mac(const char *macaddr, unsigned char mac[6])
+{
+ unsigned int m[6];
+ sscanf(macaddr, "%02x:%02x:%02x:%02x:%02x:%02x",
+ &m[0], &m[1], &m[2], &m[3], &m[4], &m[5]);
+ mac[0] = m[0];
+ mac[1] = m[1];
+ mac[2] = m[2];
+ mac[3] = m[3];
+ mac[4] = m[4];
+ mac[5] = m[5];
+}
+
/* This code is "adapted" from libbridge: it attaches the Host end of the
* network device to the bridge device specified by the command line.
*
@@ -1291,6 +1304,7 @@ static void add_to_bridge(int fd, const char *if_name, const char *br_name)
errx(1, "interface %s does not exist!", if_name);
strncpy(ifr.ifr_name, br_name, IFNAMSIZ);
+ ifr.ifr_name[IFNAMSIZ-1] = '\0';
ifr.ifr_ifindex = ifidx;
if (ioctl(fd, SIOCBRADDIF, &ifr) < 0)
err(1, "can't add %s to bridge %s", if_name, br_name);
@@ -1299,29 +1313,28 @@ static void add_to_bridge(int fd, const char *if_name, const char *br_name)
/* This sets up the Host end of the network device with an IP address, brings
* it up so packets will flow, the copies the MAC address into the hwaddr
* pointer. */
-static void configure_device(int fd, const char *devname, u32 ipaddr,
- unsigned char hwaddr[6])
+static void configure_device(int fd, struct ifreq *ifr, u32 ipaddr)
{
- struct ifreq ifr;
- struct sockaddr_in *sin = (struct sockaddr_in *)&ifr.ifr_addr;
+ struct sockaddr_in *sin = (struct sockaddr_in *)&ifr->ifr_addr;
/* Don't read these incantations. Just cut & paste them like I did! */
- memset(&ifr, 0, sizeof(ifr));
- strcpy(ifr.ifr_name, devname);
sin->sin_family = AF_INET;
sin->sin_addr.s_addr = htonl(ipaddr);
- if (ioctl(fd, SIOCSIFADDR, &ifr) != 0)
- err(1, "Setting %s interface address", devname);
- ifr.ifr_flags = IFF_UP;
- if (ioctl(fd, SIOCSIFFLAGS, &ifr) != 0)
- err(1, "Bringing interface %s up", devname);
+ if (ioctl(fd, SIOCSIFADDR, ifr) != 0)
+ err(1, "Setting %s interface address", ifr->ifr_name);
+ ifr->ifr_flags = IFF_UP;
+ if (ioctl(fd, SIOCSIFFLAGS, ifr) != 0)
+ err(1, "Bringing interface %s up", ifr->ifr_name);
+}
+static void get_mac(int fd, struct ifreq *ifr, unsigned char hwaddr[6])
+{
/* SIOC stands for Socket I/O Control. G means Get (vs S for Set
* above). IF means Interface, and HWADDR is hardware address.
* Simple! */
- if (ioctl(fd, SIOCGIFHWADDR, &ifr) != 0)
- err(1, "getting hw address for %s", devname);
- memcpy(hwaddr, ifr.ifr_hwaddr.sa_data, 6);
+ if (ioctl(fd, SIOCGIFHWADDR, ifr) != 0)
+ err(1, "getting hw address for %s", ifr->ifr_name);
+ memcpy(hwaddr, ifr->ifr_hwaddr.sa_data, 6);
}
/*L:195 Our network is a Host<->Guest network. This can either use bridging or
@@ -1333,8 +1346,10 @@ static void setup_tun_net(const char *arg)
struct device *dev;
struct ifreq ifr;
int netfd, ipfd;
- u32 ip;
- const char *br_name = NULL;
+ u32 ip = INADDR_ANY;
+ int bridging = 0;
+ char name_or_ip[IFNAMSIZ];
+ const char *p;
struct virtio_net_config conf;
/* We open the /dev/net/tun device and tell it we want a tap device. A
@@ -1367,14 +1382,30 @@ static void setup_tun_net(const char *arg)
/* If the command line was --tunnet=bridge:<name> do bridging. */
if (!strncmp(BRIDGE_PFX, arg, strlen(BRIDGE_PFX))) {
- ip = INADDR_ANY;
- br_name = arg + strlen(BRIDGE_PFX);
- add_to_bridge(ipfd, ifr.ifr_name, br_name);
- } else /* It is an IP address to set up the device with */
- ip = str2ip(arg);
+ arg += strlen(BRIDGE_PFX);
+ bridging = 1;
+ }
- /* Set up the tun device, and get the mac address for the interface. */
- configure_device(ipfd, ifr.ifr_name, ip, conf.mac);
+ /* A mac address may follow the bridge name or IP address */
+ if ((p = strchr(arg, ':')))
+ str2mac(p+1, conf.mac);
+ else {
+ p = arg + strlen(arg);
+ /* None supplied; query the randomly assigned mac. */
+ get_mac(ipfd, &ifr, conf.mac);
+ }
+
+ /* arg is now either an IP address or a bridge name */
+ strncpy(name_or_ip, arg, p-arg);
+ name_or_ip[p-arg] = '\0';
+
+ if (bridging)
+ add_to_bridge(ipfd, ifr.ifr_name, name_or_ip);
+ else
+ ip = str2ip(name_or_ip);
+
+ /* Set up the tun device. */
+ configure_device(ipfd, &ifr, ip);
/* Tell Guest what MAC address to use. */
add_feature(dev, VIRTIO_NET_F_MAC);
@@ -1384,11 +1415,14 @@ static void setup_tun_net(const char *arg)
/* We don't need the socket any more; setup is done. */
close(ipfd);
- verbose("device %u: tun net %u.%u.%u.%u\n",
- devices.device_num++,
- (u8)(ip>>24),(u8)(ip>>16),(u8)(ip>>8),(u8)ip);
- if (br_name)
- verbose("attached to bridge: %s\n", br_name);
+ devices.device_num++;
+
+ if (bridging)
+ verbose("device %u: tun net attached to bridge: %s\n",
+ devices.device_num, name_or_ip);
+ else
+ verbose("device %u: tun net: %s\n",
+ devices.device_num, name_or_ip);
}
/* Our block (disk) device should be really simple: the Guest asks for a block
@@ -1700,7 +1734,7 @@ static struct option opts[] = {
static void usage(void)
{
errx(1, "Usage: lguest [--verbose] "
- "[--tunnet=(<ipaddr>|bridge:<bridgename>)\n"
+ "[--tunnet=(<ipaddr>:<macaddr>|bridge:<bridgename>:<macaddr>)\n"
"|--block=<filename>|--initrd=<filename>]...\n"
"<mem-in-mb> vmlinux [args...]");
}
--
1.5.4.1
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