.

tmcast.py

@@ -9,7 +9,7 @@ from socket import socket, AF_INET, SOCK_DGRAM, IPPROTO_UDP, SOL_SOCKET, \
     SO_REUSEADDR, IPPROTO_IP, IP_ADD_MEMBERSHIP, IP_MULTICAST_TTL, IP_MULTICAST_LOOP,   \
     inet_aton, INADDR_ANY
 
-from golang import b
+from golang import b, u
 from golang import sync, context
 
 
@@ -17,68 +17,64 @@ group4 = '224.1.1.1'
 group6 = 'XXX'
 port   =  5678
 
-# mjoin returns socket prepated to send/receive to/from multicast group:port.
-def mjoin(group, port, ttl=2):
+# mjoin_tx returns socket prepated to send/receive to/from multicast group:port.
+def mjoin_tx(group, port, ttl=2):
     # XXX autodetect ip4/ip6 based on group addr
     sk = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)
-    sk.setsockopt(SOL_SOCKET, SO_REUSEADDR, 1)
-    sk.bind((group, port))
-
-    # join group (for rx)
-    mreq = struct.pack("4sl", inet_aton(group), INADDR_ANY)
-    sk.setsockopt(IPPROTO_IP, IP_ADD_MEMBERSHIP, mreq)
 
     # set ttl and default destination address (for tx)
     sk.setsockopt(IPPROTO_IP, IP_MULTICAST_TTL, ttl)
     sk.connect((group, port))
 
-    # receive what we send
+    # so that what we send is received locally as well
     sk.setsockopt(IPPROTO_IP, IP_MULTICAST_LOOP, 1)
-
     return sk
 
-"""
-# open_tx returns function to send to group:port.
-def open_tx(group, port, ttl=2):
+# mjoin_rx returns socket prepated to send/receive to/from multicast group:port.
+def mjoin_rx(group, port):
+    # XXX autodetect ip4/ip6 based on group addr
     sk = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)
-    sk.setsockopt(IPPROTO_IP, IP_MULTICAST_TTL, ttl)
-    # XXX IP_MULTICAST_LOOP
-    def _(data):
-        return sk.sendto(data, (group, port))
-    return _
-"""
+
+    sk.setsockopt(SOL_SOCKET, SO_REUSEADDR, 1)
+    sk.bind((group, port))
+
+    # join the group (for rx)
+    mreq = struct.pack("4sl", inet_aton(group), INADDR_ANY)
+    sk.setsockopt(IPPROTO_IP, IP_ADD_MEMBERSHIP, mreq)
+
+    return sk
 
 
 def txloop(ctx, sk, pkt):
-    print("txloop ...")
     i = 0
     while 1:
         if ctx.err():
             raise ctx.err()
         i += 1
-        pkt_ = pkt + (b'%d' % i)
-        print("tx: %r ..." % pkt_)
-        sk.send(pkt + (b'%d' % i))
+        pkt_ = pkt + (b'.%d' % i)
+        print("tx: %s ..." % u(pkt_))
+        sk.send(pkt_)
         time.sleep(1)
 
 def rxloop(ctx, sk):
-    print("rxloop ...")
     while 1:
         if ctx.err():
             raise ctx.err()
         pkt = sk.recv(4096)
-        print("rx: %r" % pkt)
+        print("rx: %s" % u(pkt))
 
 
 def main():
-    sk = mjoin(group4, port)
+    G = (group4, port)
     action = sys.argv[1]
 
     wg = sync.WorkGroup(context.background())
     if "tx" in action:
-        wg.go(txloop, sk, b(sys.argv[2]))
+        sktx = mjoin_tx(*G)
+        wg.go(txloop, sktx, b(sys.argv[2]))
     if "rx" in action:
-        wg.go(rxloop, sk)
+        skrx = mjoin_rx(*G)
+        wg.go(rxloop, skrx)
 
     wg.wait()