From 905ad6767f174dbcfef4a771019189c5eb104a29 Mon Sep 17 00:00:00 2001
From: Juanlu <juanlufont@gmail.com>
Date: Mon, 2 Dec 2024 00:15:08 +0100
Subject: [PATCH] Add script to update Transmission peer port

The script `transmission-port-update.sh` updates the _peer port_ used by
the torrent client Transmission. The peer port is the port used and
announced by Transmission to accept incoming connections.
---
 extras/scripts/transmission-port-update.sh | 121 +++++++++++++++++++++
 1 file changed, 121 insertions(+)
 create mode 100755 extras/scripts/transmission-port-update.sh

diff --git a/extras/scripts/transmission-port-update.sh b/extras/scripts/transmission-port-update.sh
new file mode 100755
index 000000000..64f12d437
--- /dev/null
+++ b/extras/scripts/transmission-port-update.sh
@@ -0,0 +1,121 @@
+#!/bin/sh
+
+# Description: This script updates the peer port for the Transmission torrent
+# client using its RPC API.
+# Author: Juan Luis Font
+
+# default values
+DEFAULT_URL="http://localhost:9091/transmission/rpc"
+WGET_OPTS="--quiet"
+
+usage() {
+    echo "Usage: $0 [OPTIONS]"
+    echo
+    echo "Options:"
+    echo "  -h, --help       Show this help message and exit."
+    echo "  -u, --user USER  Specify the Transmission RPC user name."
+    echo "                   (Omit if not required)"
+    echo "  -p, --pass PASS  Specify the Transmission RPC password."
+    echo "                   (Omit if not required)"
+    echo "  -P, --port PORT  Specify the Transmission Peer Port."
+    echo "                   REQUIRED"
+    echo "  -U, --url  URL   Specify the Transmission RPC URL."
+    echo "                   DEFAULT: ${DEFAULT_URL}"
+    echo "Example:"
+    echo "  $0 -u admin -p **** 40409"
+    exit 1
+}
+
+while [ $# -gt 0 ]; do
+    case "$1" in
+    -h | --help)
+        usage
+        ;;
+    -u | --user)
+        USERNAME="$2"
+        _USECRED=true
+        shift 2
+        ;;
+    -p | --pass)
+        PASSWORD="$2"
+        _USECRED=true
+        shift 2
+        ;;
+    -P | --port)
+        PORT="$2"
+        shift 2
+        ;;
+    -U | --url)
+        RPC_URL="$2"
+        shift 2
+        ;;
+    *)
+        echo "Unknown option: $1"
+        usage
+        ;;
+    esac
+done
+
+if [ -z "${PORT}" ]; then
+    echo "ERROR: No PORT provided!"
+    exit 1
+fi
+
+if [ "${_USECRED}" ]; then
+    # make sure username AND password were provided
+    if [ -z "${USERNAME}" ] || [ -z "${PASSWORD}" ]; then
+        echo "ERROR: Username or password not provided."
+        exit 1
+    else
+        # basic auth options, --auth-no-challenge avoids 409 Conflict
+        WGET_OPTS="
+            ${WGET_OPTS}
+            --auth-no-challenge
+            --user=${USERNAME}
+            --password=${PASSWORD}
+        "
+    fi
+fi
+
+if [ -z "${RPC_URL+x}" ]; then
+    RPC_URL="${DEFAULT_URL}"
+fi
+
+# get the X-Transmission-Session-Id
+SESSION_ID=$(
+    wget \
+        ${WGET_OPTS} \
+        --server-response \
+        "$RPC_URL" 2>&1 |
+        grep 'X-Transmission-Session-Id:' |
+        awk '{print $2}'
+)
+
+# generate payload string
+PAYLOAD=$(printf '{
+  "method": "session-set",
+  "arguments": {
+    "peer-port": %s
+  }
+}' "$PORT")
+
+# update peer host via API
+RES=$(
+    wget \
+        ${WGET_OPTS} \
+        --header="Content-Type: application/json" \
+        --header="X-Transmission-Session-Id: $SESSION_ID" \
+        --post-data="${PAYLOAD}" \
+        "$RPC_URL" \
+        -O -
+)
+
+# check string returned by wget
+SUCCESS='{"arguments":{},"result":"success"}'
+if [ "$RES" = "$SUCCESS" ]; then
+    echo "Success! Peer port updated to ${PORT}"
+    exit 0
+else
+    echo "ERROR: Could not update peer port"
+    exit 1
+fi