xend: Add interface name definition support for xend-relocation-address

Add a new feature for xend-relocation-address option to support
definition by interface name which can be useful for people having
e.g. a cluster environment with multiple network interfaces on all of
the machines with only one reserved to be registered to a private
cluster network. This way they won't need to specify the relocation
address manually on all the machines but just simple providing the
interface name to get the IP address from would do the job (all the
machines have to have this interface named the same to make it
working, of course).

Technically it reads the interface name and gets its IP address using
ioctl call of SIOCGIFADDR and if the interface doesn't have the
address, i.e. if non-existing interface or hostname was provided the
original ifname is returned to preserve the old behaviour.

Signed-off-by: Michal Novotny <minovotn@redhat.com>

diff --git a/tools/examples/xend-config.sxp b/tools/examples/xend-config.sxp
index 6c056d4e05a7c8386be2fce3bf95ea4c4232922d..7ab7eb8f380586550f1dc2f24c2266148911b30e 100644 (file)
--- a/tools/examples/xend-config.sxp
+++ b/tools/examples/xend-config.sxp
@@ -110,6 +110,8 @@
 # Address xend should listen on for relocation-socket connections, if
 # xend-relocation-server is set.
 # Meaning and default as for xend-address above.
+# Also, interface name is allowed (e.g. eth0) there to get the
+# relocation address to be bound on.
 #(xend-relocation-address '')
 
 # The hosts allowed to talk to the relocation port.  If this is empty (the

diff --git a/tools/python/xen/web/tcp.py b/tools/python/xen/web/tcp.py
index c4436d506e6dc62cd540f91584de7c82050e9c7a..222737514a0ce0b66a7bef7483d417c29306c096 100644 (file)
--- a/tools/python/xen/web/tcp.py
+++ b/tools/python/xen/web/tcp.py
@@ -21,6 +21,8 @@ import errno
 import re
 import socket
 import time
+import fcntl     # For get_interface_addr
+import struct    # For get_interface_addr
 
 import connection
 
@@ -35,6 +37,49 @@ class TCPListener(connection.SocketListener):
         self.hosts_allow = hosts_allow
         connection.SocketListener.__init__(self, protocol_class)
 
+    def isValidHex(self, word):
+        # If we have empty word we treat it as valid
+        if len(word) == 0:
+            return True
+        try:
+            int(word, 16)
+            return True
+        except ValueError:
+            return False
+
+    def isValidIP(self, ipaddr):
+        # Check for IPv4 address
+        numValid = 0
+        tmp = ipaddr.split('.')
+        for byte in tmp:
+            if byte.isdigit():
+                numValid += 1
+
+        if numValid == len(tmp):
+            return True
+
+        # Check for IPv6 address
+        numValid = 0
+        tmp = ipaddr.split(':')
+        for word in tmp:
+            if self.isValidHex(word):
+                numValid += 1
+
+        return numValid == len(tmp)
+
+    def getIfAddr(self, ifname):
+        s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+        try:
+            x = socket.inet_ntoa(fcntl.ioctl(
+                s.fileno(),
+                0x8915,  # SIOCGIFADDR
+                struct.pack('256s', ifname[:15])
+            )[20:24])
+            s.close()
+        except Exception, e:
+            x = ifname
+
+        return x
 
     def createSocket(self):
         sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
@@ -46,6 +91,9 @@ class TCPListener(connection.SocketListener):
         timeout = time.time() + 30
         while True:
             try:
+                if not self.isValidIP(self.interface):
+                    self.interface = self.getIfAddr(self.interface)
+                log.debug("Listening on %s:%s" % (self.interface, self.port))
                 sock.bind((self.interface, self.port))
                 return sock
             except socket.error, (_errno, strerrno):
@@ -78,6 +126,49 @@ class SSLTCPListener(TCPListener):
 
         TCPListener.__init__(self, protocol_class, port, interface, hosts_allow)
 
+    def isValidHex(self, word):
+        # If we have empty word we treat it as valid
+        if len(word) == 0:
+            return True
+        try:
+            int(word, 16)
+            return True
+        except ValueError:
+            return False
+
+    def isValidIP(self, ipaddr):
+        # Check for IPv4 address
+        numValid = 0
+        tmp = ipaddr.split('.')
+        for byte in tmp:
+            if byte.isdigit():
+                numValid += 1
+
+        if numValid == len(tmp):
+            return True
+
+        # Check for IPv6 address
+        numValid = 0
+        tmp = ipaddr.split(':')
+        for word in tmp:
+            if self.isValidHex(word):
+                numValid += 1
+
+        return numValid == len(tmp)
+
+    def getIfAddr(self, ifname):
+        s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+        try:
+            x = socket.inet_ntoa(fcntl.ioctl(
+                s.fileno(),
+                0x8915,  # SIOCGIFADDR
+                struct.pack('256s', ifname[:15])
+            )[20:24])
+            s.close()
+        except Exception, e:
+            x = ifname
+
+        return x
 
     def createSocket(self):
         from OpenSSL import SSL
@@ -97,6 +188,9 @@ class SSLTCPListener(TCPListener):
         timeout = time.time() + 30
         while True:
             try:
+                if not self.isValidIP(self.interface):
+                    self.interface = self.getIfAddr(self.interface)
+                log.debug("Listening on %s:%s" % (self.interface, self.port))
                 sock.bind((self.interface, self.port))
                 return sock
             except socket.error, (_errno, strerrno):