replaced multicast_expert by own socket handling

examples/simple_send_and_receive/send_psn.py

@@ -26,14 +26,14 @@
 
 try:
     tracker_num = int(sys.argv[1])
-    ip_addr = sys.argv[2]
-    mcast_ip = None
+    iface_ip = sys.argv[2]
+    mcast_grp = None
 
     if sys.argv[3]:
-        mcast_ip = sys.argv[3]
+        mcast_grp = sys.argv[3]
 
 except Exception as e:
-    print("Args: tracker_num ip_addr mcast_ip (opt).")
+    print("Args: tracker_num iface_ip mcast_grp (opt).")
     print(e)
 
 start_time_us = time.time_ns() // 1000
@@ -161,9 +161,9 @@
 
         pypsn.send_psn_packet(
             psn_packet=psn_info_packet_bytes,
-            mcast_ip=mcast_ip,
-            ip_addr=ip_addr,
+            iface_ip=iface_ip,
             port=56565,
+            mcast_grp=mcast_grp,
         )
 
     psn_data.info.timestamp = elapsed_time_us
@@ -185,7 +185,7 @@
 
     pypsn.send_psn_packet(
         psn_packet=psn_data_packet_bytes,
-        mcast_ip=mcast_ip,
-        ip_addr=ip_addr,
+        iface_ip=iface_ip,
         port=56565,
+        mcast_grp=mcast_grp,
     )

pyproject.toml

@@ -21,7 +21,6 @@ classifiers = [
   "Programming Language :: Python"
 ]
 dependencies = [
-  "multicast_expert>=1.4.0",
 ]
 
 [tool.setuptools]

pypsn/__init__.py

@@ -3,13 +3,13 @@
 Pure python PSN interface.
 """
 
+import os
+import sys
 import socket
 from struct import pack, unpack
 from enum import IntEnum
 from typing import List
-import os
 from threading import Thread
-import multicast_expert
 
 __version__ = "0.2.4"
 
@@ -655,23 +655,74 @@ def prepare_psn_data_packet_bytes(data_packet: PsnDataPacket):
 
 
 def send_psn_packet(
-    psn_packet, mcast_ip="236.10.10.10", ip_addr="127.0.0.1", port=56565
+    psn_packet,
+    iface_name="",
+    iface_ip="127.0.0.1",
+    port=56565,
+    mcast_grp="236.10.10.10",
+    transmit_block_size=9216,
+    time_to_live=31,
 ):
     """Send psn packet.
-        If mcast_ip is specified, it does via multicast with the help
-        of multicast_expert. If not, it does via simple unicast.
+        If mcast_ip is specified, it does via multicast.
+        If not, it does via simple unicast.
+        !IPV4 ONLY!
+        Thanks to https://gist.github.com/ifundef/09d3ec98459a856052bd935bd91683ed
+
 
     Args:
-        psn_packet (_type_): as bytes
-        mcast_ip (str, optional): multicastip. Default: "236.10.10.10"
-        ip_addr (str, optional): local ip. Default: 127.0.0.1
+        psn_packet (bytes): Use binary/bytes, not text/strings for data
+        iface_name (str, optional): local interface name
+        iface_ip (str, optional): local interface ip. Default: 127.0.0.1
         port (int, optional): udp port. Default: 56565
+        mcast_ip (str, optional): multicastip. Default: "236.10.10.10"
+        transmit_block_size (int, optional): max udp packet (65535) -
+        udp header (8) - ip header (20) = 65507. Defaults to 65507.
+        time_to_live (int, optional): time to live (TTL) of sent
+        packets. Defaults to 31 (maximum recommended for local network).
+
+    Raises:
+        AttributeError
     """
-    if mcast_ip:
-        with multicast_expert.McastTxSocket(
-            socket.AF_INET, mcast_ips=[mcast_ip], iface_ip=ip_addr
-        ) as mcast_tx_sock:
-            mcast_tx_sock.sendto(psn_packet, (mcast_ip, port))
+
+    if not iface_name:
+        iface_name = socket.inet_ntoa(pack("i", socket.INADDR_ANY))
+
+    output_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, socket.IPPROTO_UDP)
+    output_socket.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_TTL, time_to_live)
+
+    if mcast_grp:
+        ip_addr = mcast_grp
+
+        if sys.platform == "win32":
+            mreq = struct.pack(
+                "4s4s", socket.inet_aton(mcast_grp), socket.inet_aton(iface_ip)
+            )
+            output_socket.setsockopt(socket.IPPROTO_IP, socket.IP_ADD_MEMBERSHIP, mreq)
+
+        # disable Path MTU Discovery (PMTUD) as it doesn't address multicast
+        # and silently drops any IP packets > a remote network's MTU
+        if sys.platform == "linux" or sys.platform == "darwin":
+            try:
+                output_socket.setsockopt(
+                    socket.IPPROTO_IP, socket.IP_MTU_DISCOVER, socket.IP_PMTUDISC_DONT
+                )
+            except AttributeError as err:
+                # use numeric values instead of symbolic names
+                # see /usr/include/linux/in.h
+                if "IP_MTU_DISCOVER" in str(err) or "IP_PMTUDISC_DONT" in str(err):
+                    output_socket.setsockopt(socket.IPPROTO_IP, 10, 0)
+                else:
+                    raise err
+
+        # sent multicast packets should be looped back to local sockets
+        # by default, but set IP_MULTICAST_LOOP to true to insure such
+        output_socket.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_LOOP, True)
+        output_socket.setsockopt(
+            socket.IPPROTO_IP, socket.IP_MULTICAST_IF, socket.inet_aton(iface_ip)
+        )
     else:
-        sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
-        sock.sendto(psn_packet, (ip_addr, port))
+        ip_addr = iface_ip
+
+    output_socket.sendto(psn_packet, (ip_addr, port))
+    output_socket.close()