[Mocap][Multicast][IGMP] create a script to force send IGMP report to…

… router periodically (#641)

aerial_robot_base/bin/install_igmp_report.sh

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+#!/bin/bash
+
+# Define the path for the temporary file
+TEMP_CRON_FILE=$(mktemp)
+
+# Copy python file to the home directory
+FILE_NAME="send_igmp_report.py"
+cp `rospack find aerial_robot_base`/scripts/$FILE_NAME $HOME/$FILE_NAME
+
+# Retrieve the current crontab and save it to the temporary file
+sudo crontab -l 2>/dev/null > "$TEMP_CRON_FILE"
+
+# Add a new job
+CRON_COMMAND="*/2 * * * * /usr/bin/python3 $HOME/$FILE_NAME >> /var/log/force_send_GIMP_report.log 2>&1"
+grep -qxF "$CRON_COMMAND" "$TEMP_CRON_FILE" ||  echo "$CRON_COMMAND" >> "$TEMP_CRON_FILE"
+
+# Update the crontab
+sudo crontab "$TEMP_CRON_FILE"
+
+# Delete the temporary file
+rm -f "$TEMP_CRON_FILE"
+
+echo "Crontab has been updated."

aerial_robot_base/scripts/send_igmp_report.py

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+import socket
+import struct
+import netifaces
+import datetime
+
+def get_wifi_ip():
+    # Get the default gateway interface
+    gateway_interface = netifaces.gateways().get('default')
+    if gateway_interface:
+        gateway_interface_name = gateway_interface[2][-1]
+
+        # Get the IP address of the Wi-Fi interface
+        wifi_ip = netifaces.ifaddresses(gateway_interface_name).get(netifaces.AF_INET)
+        if wifi_ip:
+            return wifi_ip[0]['addr']
+    return None  # Return None if Wi-Fi interface is not found
+
+def send_igmp_v2_membership_report(group_ip, interface_ip):
+    # IGMPv2 Membership Report packet format
+    # Type (1 byte), Max Resp Time (1 byte), Checksum (2 bytes), Group Address (4 bytes)
+
+    IGMP_MEMBERSHIP_REPORT_TYPE = 0x16  # IGMPv2 Membership Report
+    MAX_RESP_TIME = 0  # Not used in Membership Report
+    CHECKSUM_PLACEHOLDER = 0
+
+    # Convert group IP to bytes
+    group_bytes = socket.inet_aton(group_ip)
+
+    # Create IGMP packet with a placeholder checksum
+    igmp_packet = struct.pack('!BBH4s',
+                               IGMP_MEMBERSHIP_REPORT_TYPE,
+                               MAX_RESP_TIME,
+                               CHECKSUM_PLACEHOLDER,
+                               group_bytes)
+
+    # Calculate checksum
+    def calculate_checksum(data):
+        if len(data) % 2:
+            data += b'\x00'
+        checksum = sum(struct.unpack('!%dH' % (len(data) // 2), data))
+        checksum = (checksum >> 16) + (checksum & 0xFFFF)
+        checksum += checksum >> 16
+        return ~checksum & 0xFFFF
+
+    checksum = calculate_checksum(igmp_packet)
+
+    # Rebuild the packet with the correct checksum
+    igmp_packet = struct.pack('!BBH4s',
+                               IGMP_MEMBERSHIP_REPORT_TYPE,
+                               MAX_RESP_TIME,
+                               checksum,
+                               group_bytes)
+
+    # Create a raw socket
+    sock = socket.socket(socket.AF_INET, socket.SOCK_RAW, socket.IPPROTO_IGMP)
+
+    # Bind to the interface
+    sock.setsockopt(socket.SOL_IP, socket.IP_MULTICAST_IF, socket.inet_aton(interface_ip))
+
+    # Send the IGMP packet
+    sock.sendto(igmp_packet, (group_ip, 0))
+    dt_now = datetime.datetime.now()
+    print("[{}] IGMPv2 Membership Report sent to {} from {}".format(dt_now, group_ip, interface_ip))
+
+# Example usage
+group_ip = "239.255.42.99"  # Multicast group address
+interface_ip = get_wifi_ip()  # Automatically detect the IP address of the Wi-Fi interface
+if interface_ip:
+    send_igmp_v2_membership_report(group_ip, interface_ip)
+else:
+    dt_now = datetime.datetime.now()
+    print("[{}] Wi-Fi interface not found.".format(dt_now))