1 files changed, 91 insertions, 0 deletions
diff --git a/pysnmp/carrier/sockmsg.py b/pysnmp/carrier/sockmsg.py
new file mode 100644
index 0000000..d0666eb
--- /dev/null
+++ b/pysnmp/carrier/sockmsg.py
@@ -0,0 +1,91 @@
+#
+# The following routines act like sendto()/recvfrom() calls but additionally
+# support local address retrieval (what can be useful when listening on 
+# 0.0.0.0 or [::]) and source address spoofing (for transparent proxying).
+#
+# These routines are based on POSIX sendmsg()/recvmsg() calls which were made
+# available since Python 3.3. Therefore this module is only Python 3.x 
+# compatible.
+#
+# Parts of the code below is taken from:
+# http://carnivore.it/2012/10/12/python3.3_sendmsg_and_recvmsg
+#
+try:
+    import ctypes
+    import ipaddress
+except ImportError:
+    def getRecvFrom(addressType):
+        raise error.CarrierError('sendmsg()/recvmsg() interface is not supported by this OS and/or Python version')
+
+    def getSendTo(addressType):
+        raise error.CarrierError('sendmsg()/recvmsg() interface is not supported by this OS and/or Python version')
+else:
+    import sys
+    import socket
+    from pysnmp import debug
+    from pysnmp.carrier import sockfix, error
+
+    uint32_t = ctypes.c_uint32
+    in_addr_t = uint32_t
+ 
+    class in_addr(ctypes.Structure):
+        _fields_ = [('s_addr', in_addr_t)]
+ 
+    class in6_addr_U(ctypes.Union):
+        _fields_ = [
+            ('__u6_addr8', ctypes.c_uint8 * 16),
+            ('__u6_addr16', ctypes.c_uint16 * 8),
+            ('__u6_addr32', ctypes.c_uint32 * 4),
+        ]
+ 
+    class in6_addr(ctypes.Structure):
+        _fields_ = [
+            ('__in6_u', in6_addr_U),
+        ]
+ 
+    class in_pktinfo(ctypes.Structure):
+        _fields_ = [
+            ('ipi_ifindex', ctypes.c_int),
+            ('ipi_spec_dst', in_addr),
+            ('ipi_addr', in_addr),
+        ]
+ 
+    class in6_pktinfo(ctypes.Structure):
+        _fields_ = [
+            ('ipi6_addr', in6_addr),
+            ('ipi6_ifindex', ctypes.c_uint),
+        ]
+
+    def getRecvFrom(addressType):
+        def recvfrom(s, sz):
+            _to = None
+            data, ancdata, msg_flags, _from = s.recvmsg(sz, socket.CMSG_LEN(sz))
+            for anc in ancdata:
+                if anc[0] == socket.SOL_IP and anc[1] == socket.IP_PKTINFO:
+                    addr = in_pktinfo.from_buffer_copy(anc[2])
+                    addr = ipaddress.IPv4Address(memoryview(addr.ipi_addr).tobytes())
+                    _to = (str(addr),s.getsockname()[1])
+                elif anc[0] == socket.SOL_IPV6 and anc[1] == socket.IPV6_PKTINFO:
+                    addr = in6_pktinfo.from_buffer_copy(anc[2])
+                    addr = ipaddress.ip_address(memoryview(addr.ipi6_addr).tobytes())
+                    _to = (str(addr),s.getsockname()[1])
+            return data, addressType(_from).setLocalAddress(_to)
+        return recvfrom
+ 
+    def getSendTo(addressType):
+        def sendto(s, _data, _to):
+            ancdata = []
+            if type(_to) == addressType:
+                addr = ipaddress.ip_address(_to.getLocalAddress()[0])
+            else:
+                addr = ipaddress.ip_address(s.getsockname()[0])
+            if type(addr) == ipaddress.IPv4Address:
+                _f = in_pktinfo()
+                _f.ipi_spec_dst = in_addr.from_buffer_copy(addr.packed)
+                ancdata = [(socket.SOL_IP, socket.IP_PKTINFO, memoryview(_f).tobytes())]
+            elif s.family == socket.AF_INET6 and type(addr) == ipaddress.IPv6Address:
+                _f = in6_pktinfo()
+                _f.ipi6_addr = in6_addr.from_buffer_copy(addr.packed)
+                ancdata = [(socket.SOL_IPV6, socket.IPV6_PKTINFO, memoryview(_f).tobytes())]
+            return s.sendmsg([_data], ancdata, 0, _to)
+        return sendto