Adding support for specifying TTL of the multicast traffic. Defaulting to 0 (instead of 1).

README.md

@@ -61,7 +61,7 @@ services:
 
 * **to_bus** and **from_bus**
 
-  Pipes data to or from the `bus`. Expects a single argument, the `bus_id`, which needs to be in the range 0-255.
+  Pipes data to or from the `bus`. Expects a single argument, the `bus_id`, which needs to be in the range 0-255. In addition, `to_bus` accepts the optional argument `--ttl` which can be used to set the TTL (Time-to-Live) of the outgoing multicast datagram, it defaults to `--ttl 0` (which constrains the traffic to the own host only).
 
 * **record**
 
@@ -87,6 +87,7 @@ services:
 
   Rate limit the flow through a pipe on a line-by-line basis. Expects a single required argument, `interval`, and an optional argument, `--key` with a format specification of how to find the key of each line whereby to "group" the flow.
 
+
 ### 3rd-party tools
 
 * **socat**
@@ -131,6 +132,12 @@ services:
         restart: always
         command: ["from_bus 3 | socat STDIN UDP4-DATAGRAM:1458"]
 
+    sink2:
+        image: ghcr.io/mo-rise/porla
+        network_mode: host
+        restart: always
+        command: ["from_bus 3 | to_bus 255 --ttl 1"]
+
     record_1:
         image: ghcr.io/mo-rise/porla
         network_mode: host

bash-init.sh

@@ -3,7 +3,19 @@
 set -euo pipefail
 
 function to_bus () {
-    socat STDIN "UDP4-DATAGRAM:239.111.42.$1:12737"
+    bus="$1"
+
+    #Read the argument values
+    while [ $# -gt 0 ]
+    do
+        case "$1" in
+            --ttl) ttl="$2"; shift;;
+            --) shift;;
+        esac
+        shift;
+    done
+
+    socat STDIN "UDP4-DATAGRAM:239.111.42.$bus:12737,ip-multicast-ttl=${ttl:-0}"
 }
 export to_bus
 

tests/test_porla.bats

@@ -30,7 +30,7 @@ teardown() {
 
     docker run -d -v "$TMP_DIR":/recordings --network=host porla "from_bus 37 | record /recordings/out.txt"
 
-    docker run -v "$TMP_DIR":/recordings --network=host porla "cat /recordings/test.txt | to_bus 37"
+    docker run -v "$TMP_DIR":/recordings --network=host porla "cat /recordings/test.txt | to_bus 37 --ttl 1"
 
     assert_exists "$TMP_DIR"/out.txt