From 22a579a19c1f4db634c9bf516936b93b925df5de Mon Sep 17 00:00:00 2001
From: Nicolas Chan <nicolas@nicolaschan.com>
Date: Wed, 3 Mar 2021 22:12:28 -0800
Subject: [PATCH] Add rcon to backup script

---
 README.md         |   5 +-
 backup.sh         | 125 ++++++++++++++++++++++++++++--
 rcon.sh           | 188 ++++++++++++++++++++++++----------------------
 test/mock_rcon.py |  31 ++++++++
 test/test.sh      |  24 +++++-
 5 files changed, 272 insertions(+), 101 deletions(-)
 create mode 100644 test/mock_rcon.py

diff --git a/README.md b/README.md
index 1be40a6..b6bda51 100644
--- a/README.md
+++ b/README.md
@@ -10,7 +10,6 @@ Supports servers running in [screen](https://en.wikipedia.org/wiki/GNU_Screen),
 - Manage deletion of old backups
   - "thin" - keep last 24 hourly, last 30 daily, and use remaining space for weekly backups
   - "sequential" - delete oldest backup
-- Choose your own compression algorithm (tested with: `gzip`, `xz`, `zstd`)
 - Works on vanilla (no plugins required)
 - Print backup status to the Minecraft chat
 
@@ -66,11 +65,11 @@ tar -xzvf /path/to/backups/2019-04-09_02-15-01.tar.gz
 Then you can move your restored world (`restored-world` in this case) to your Minecraft server folder and rename it (usually called `world`) so the Minecraft server uses it.
 
 ## Why not use `tar` directly?
-If the Minecraft server is currently running, you need to disable world autosaving, or you will likely get an error like this:
+If you use `tar` while the server is running, you will likely get an error like this because Minecraft autosaves the world periodically:
 ```
 tar: /some/path/here/world/region/r.1.11.mca: file changed as we read it
 ```
-This script will take care of disabling and then re-enabling autosaving for you, and also alert players in the chat of successful backups or errors. This script also manages deleting old backups.
+To fix this problem, the backup script disables autosaving with the `save-off` Minecraft command before running `tar` and then re-enables autosaving after `tar` is done. 
 
 ## Help
 - Make sure the compression algorithm you specify is installed on your system. (zstd is not installed by default)
diff --git a/backup.sh b/backup.sh
index 9f2ad43..1b0a487 100755
--- a/backup.sh
+++ b/backup.sh
@@ -47,9 +47,9 @@ while getopts 'a:cd:e:f:hi:l:m:o:p:qs:vw:' FLAG; do
        echo "-o    Output directory"
        echo "-p    Prefix that shows in Minecraft chat (default: Backup)"
        echo "-q    Suppress warnings"
-       echo "-s    Minecraft server screen name"
+       echo "-s    Screen name, tmux session name, or hostname:port:password for rcon"
        echo "-v    Verbose mode"
-       echo "-w    Window manager: screen (default) or tmux"
+       echo "-w    Window manager: screen (default), tmux, rcon"
        exit 0
        ;;
     i) SERVER_WORLD=$OPTARG ;;
@@ -71,6 +71,116 @@ log-warning () {
   echo -e "\033[0;33mWARNING:\033[0m $*"
 }
 
+rcon-command () {
+  HOST="$(echo $1 | cut -d: -f1)"
+  PORT="$(echo $1 | cut -d: -f2)"
+  PASSWORD="$(echo $1 | cut -d: -f3-)"
+  COMMAND="$2"
+
+  reverse-hex-endian () {
+    # Given a 4-byte hex integer, reverse endianness
+    while read -r -d '' -N 8 INTEGER; do
+      echo "$INTEGER" | sed -E 's/(..)(..)(..)(..)/\4\3\2\1/'
+    done
+  }
+
+  decode-hex-int () {
+    # decode little-endian hex integer
+    while read -r -d '' -N 8 INTEGER; do
+      BIG_ENDIAN_HEX=$(echo "$INTEGER" | reverse-hex-endian)
+      echo "$((16#$BIG_ENDIAN_HEX))"
+    done
+  }
+
+  stream-to-hex () {
+    xxd -ps
+  }
+
+  hex-to-stream () {
+    xxd -ps -r
+  }
+
+  encode-int () {
+    # Encode an integer as 4 bytes in little endian and return as hex
+    INT="$1"
+    # Source: https://stackoverflow.com/a/9955198
+    printf "%08x" "$INT" | sed -E 's/(..)(..)(..)(..)/\4\3\2\1/' 
+  }
+
+  encode () {
+    # Encode a packet type and payload for the rcon protocol
+    TYPE="$1"
+    PAYLOAD="$2"
+    REQUEST_ID="$3"
+    PAYLOAD_LENGTH="${#PAYLOAD}" 
+    TOTAL_LENGTH="$((4 + 4 + PAYLOAD_LENGTH + 1 + 1))"
+
+    OUTPUT=""
+    OUTPUT+=$(encode-int "$TOTAL_LENGTH")
+    OUTPUT+=$(encode-int "$REQUEST_ID")
+    OUTPUT+=$(encode-int "$TYPE")
+    OUTPUT+=$(echo -n "$PAYLOAD" | stream-to-hex)
+    OUTPUT+="0000"
+    
+    echo -n "$OUTPUT" | hex-to-stream 
+  }
+
+  read-response () {
+    # read next response packet and return the payload text
+    HEX_LENGTH=$(head -c4 <&3 | stream-to-hex | reverse-hex-endian)
+    LENGTH=$((16#$HEX_LENGTH))
+
+    RESPONSE_PAYLOAD=$(head -c $LENGTH <&3 | stream-to-hex)
+    echo -n "$RESPONSE_PAYLOAD"
+  }
+
+  response-request-id () {
+    echo -n "${1:0:8}" | decode-hex-int
+  }
+
+  response-type () {
+    echo -n "${1:8:8}" | decode-hex-int
+  }
+
+  response-payload () {
+    echo -n "${1:16:-4}" | hex-to-stream
+  }
+
+  login () {
+    PASSWORD="$1"
+    encode 3 "$PASSWORD" 12 >&3
+
+    RESPONSE=$(read-response "$IN_PIPE")
+
+    RESPONSE_REQUEST_ID=$(response-request-id "$RESPONSE")
+    if [ "$RESPONSE_REQUEST_ID" -eq -1 ] || [ "$RESPONSE_REQUEST_ID" -eq 4294967295 ]; then
+      log-warning "RCON connection failed: Wrong RCON password" 1>&2
+      return 1
+    fi
+  }
+
+  run-command () {
+    COMMAND="$1"
+    
+    # encode 2 "$COMMAND" 13 >> "$OUT_PIPE"
+    encode 2 "$COMMAND" 13 >&3
+
+    RESPONSE=$(read-response "$IN_PIPE")
+    response-payload "$RESPONSE"
+  }
+
+  # Open a TCP socket
+  # Source: https://www.xmodulo.com/tcp-udp-socket-bash-shell.html
+  exec 3<>/dev/tcp/"$HOST"/"$PORT"
+
+  login "$PASSWORD" || return 1
+  run-command "$COMMAND"
+
+  # Close the socket
+  exec 3<&-
+  exec 3>&-
+}
+
 if [[ $COMPRESSION_FILE_EXTENSION == "." ]]; then
   COMPRESSION_FILE_EXTENSION=""
 fi
@@ -78,7 +188,7 @@ fi
 # Check for missing encouraged arguments
 if ! $SUPPRESS_WARNINGS; then
   if [[ $SCREEN_NAME == "" ]]; then
-    log-warning "Minecraft screen name not specified (use -s)"
+    log-warning "Minecraft screen/tmux/rcon location not specified (use -s)"
   fi
 fi
 # Check for required arguments
@@ -109,9 +219,11 @@ execute-command () {
   local COMMAND=$1
   if [[ $SCREEN_NAME != "" ]]; then
     case $WINDOW_MANAGER in
-      "screen") screen -S $SCREEN_NAME -p 0 -X stuff "$COMMAND$(printf \\r)"
+      "screen") screen -S "$SCREEN_NAME" -p 0 -X stuff "$COMMAND$(printf \\r)"
         ;;
-      "tmux") tmux send-keys -t $SCREEN_NAME "$COMMAND" ENTER
+      "tmux") tmux send-keys -t "$SCREEN_NAME" "$COMMAND" ENTER
+        ;;
+      "rcon") rcon-command "$SCREEN_NAME" "$COMMAND"
         ;;
     esac
   fi
@@ -238,6 +350,9 @@ delete-thinning () {
   delete-sequentially
 }
 
+# Ensure directory exists
+mkdir -p "$(dirname $ARCHIVE_PATH)"
+
 # Disable world autosaving
 execute-command "save-off"
 
diff --git a/rcon.sh b/rcon.sh
index bf5e42e..cc4f679 100755
--- a/rcon.sh
+++ b/rcon.sh
@@ -1,96 +1,102 @@
 #!/usr/bin/env bash
 
-reverse-hex-endian () {
-  # Given a 4-byte hex integer, reverse endianness
-  while read -r -d '' -N 8 INTEGER; do
-    echo "$INTEGER" | sed -E 's/(..)(..)(..)(..)/\4\3\2\1/'
-  done
-}
-
-decode-hex-int () {
-  # decode little-endian hex integer
-  while read -r -d '' -N 8 INTEGER; do
-    BIG_ENDIAN_HEX=$(echo "$INTEGER" | reverse-hex-endian)
-    echo "$((16#$BIG_ENDIAN_HEX))"
-  done
-}
-
-encode-int () {
-  # Encode an integer as 4 bytes in little endian and return as hex
-  INT="$1"
-  # Source: https://stackoverflow.com/a/9955198
-  printf "%08x" "$INT" | sed -E 's/(..)(..)(..)(..)/\4\3\2\1/' 
-}
-
-encode () {
-  # Encode a packet type and payload for the rcon protocol
-  TYPE="$1"
-  PAYLOAD="$2"
-  REQUEST_ID="$3"
-  PAYLOAD_LENGTH="${#PAYLOAD}" 
-  TOTAL_LENGTH="$((4 + 4 + PAYLOAD_LENGTH + 1 + 1))"
-
-  OUTPUT=""
-  OUTPUT+=$(encode-int "$TOTAL_LENGTH")
-  OUTPUT+=$(encode-int "$REQUEST_ID")
-  OUTPUT+=$(encode-int "$TYPE")
-  OUTPUT+=$(echo -n "$PAYLOAD" | xxd -ps)
-  OUTPUT+="0000"
-  
-  echo -n "$OUTPUT" | xxd -ps -r
-}
-
-read-response () {
-  # read next response packet and return the payload text
-  IN_PIPE="$1"
-  # HEX_LENGTH=$(head -c4 "$IN_PIPE" | xxd -ps | reverse-hex-endian)
-  HEX_LENGTH=$(head -c4 <&3 | xxd -ps | reverse-hex-endian)
-  LENGTH=$((16#$HEX_LENGTH))
-
-  RESPONSE_PAYLOAD=$(head -c $LENGTH <&3 | xxd -ps)
-  echo -n "$RESPONSE_PAYLOAD"
-}
-
-response-request-id () {
-  echo -n "${1:0:8}" | decode-hex-int
-}
-
-response-type () {
-  echo -n "${1:8:8}" | decode-hex-int
-}
-
-response-payload () {
-  echo -n "${1:16:-4}" | xxd -r -ps
-}
-
-login () {
-  PASSWORD="$1"
-  encode 3 "$PASSWORD" 12 >&3
-
-  RESPONSE=$(read-response "$IN_PIPE")
-
-  RESPONSE_REQUEST_ID=$(response-request-id "$RESPONSE")
-  if [ "$RESPONSE_REQUEST_ID" -eq -1 ] || [ "$RESPONSE_REQUEST_ID" -eq 4294967295 ]; then
-    echo "Authentication failed: Wrong RCON password" 1>&2
-    return 1
-  fi
-}
-
-run-command () {
-  COMMAND="$1"
-  
-  # encode 2 "$COMMAND" 13 >> "$OUT_PIPE"
-  encode 2 "$COMMAND" 13 >&3
-
-  RESPONSE=$(read-response "$IN_PIPE")
-  response-payload "$RESPONSE"
-}
-
 rcon-command () {
-  HOST="$1"
-  PORT="$2"
-  PASSWORD="$3"
-  COMMAND="$4"
+  HOST="$(echo $1 | cut -d: -f1)"
+  PORT="$(echo $1 | cut -d: -f2)"
+  PASSWORD="$(echo $1 | cut -d: -f3-)"
+  COMMAND="$2"
+
+  reverse-hex-endian () {
+    # Given a 4-byte hex integer, reverse endianness
+    while read -r -d '' -N 8 INTEGER; do
+      echo "$INTEGER" | sed -E 's/(..)(..)(..)(..)/\4\3\2\1/'
+    done
+  }
+
+  decode-hex-int () {
+    # decode little-endian hex integer
+    while read -r -d '' -N 8 INTEGER; do
+      BIG_ENDIAN_HEX=$(echo "$INTEGER" | reverse-hex-endian)
+      echo "$((16#$BIG_ENDIAN_HEX))"
+    done
+  }
+
+  stream-to-hex () {
+    xxd -ps
+  }
+
+  hex-to-stream () {
+    xxd -ps -r
+  }
+
+  encode-int () {
+    # Encode an integer as 4 bytes in little endian and return as hex
+    INT="$1"
+    # Source: https://stackoverflow.com/a/9955198
+    printf "%08x" "$INT" | sed -E 's/(..)(..)(..)(..)/\4\3\2\1/' 
+  }
+
+  encode () {
+    # Encode a packet type and payload for the rcon protocol
+    TYPE="$1"
+    PAYLOAD="$2"
+    REQUEST_ID="$3"
+    PAYLOAD_LENGTH="${#PAYLOAD}" 
+    TOTAL_LENGTH="$((4 + 4 + PAYLOAD_LENGTH + 1 + 1))"
+
+    OUTPUT=""
+    OUTPUT+=$(encode-int "$TOTAL_LENGTH")
+    OUTPUT+=$(encode-int "$REQUEST_ID")
+    OUTPUT+=$(encode-int "$TYPE")
+    OUTPUT+=$(echo -n "$PAYLOAD" | stream-to-hex)
+    OUTPUT+="0000"
+    
+    echo -n "$OUTPUT" | hex-to-stream 
+  }
+
+  read-response () {
+    # read next response packet and return the payload text
+    HEX_LENGTH=$(head -c4 <&3 | stream-to-hex | reverse-hex-endian)
+    LENGTH=$((16#$HEX_LENGTH))
+
+    RESPONSE_PAYLOAD=$(head -c $LENGTH <&3 | stream-to-hex)
+    echo -n "$RESPONSE_PAYLOAD"
+  }
+
+  response-request-id () {
+    echo -n "${1:0:8}" | decode-hex-int
+  }
+
+  response-type () {
+    echo -n "${1:8:8}" | decode-hex-int
+  }
+
+  response-payload () {
+    echo -n "${1:16:-4}" | hex-to-stream
+  }
+
+  login () {
+    PASSWORD="$1"
+    encode 3 "$PASSWORD" 12 >&3
+
+    RESPONSE=$(read-response "$IN_PIPE")
+
+    RESPONSE_REQUEST_ID=$(response-request-id "$RESPONSE")
+    if [ "$RESPONSE_REQUEST_ID" -eq -1 ] || [ "$RESPONSE_REQUEST_ID" -eq 4294967295 ]; then
+      echo "Authentication failed: Wrong RCON password" 1>&2
+      return 1
+    fi
+  }
+
+  run-command () {
+    COMMAND="$1"
+    
+    # encode 2 "$COMMAND" 13 >> "$OUT_PIPE"
+    encode 2 "$COMMAND" 13 >&3
+
+    RESPONSE=$(read-response "$IN_PIPE")
+    response-payload "$RESPONSE"
+  }
 
   # Open a TCP socket
   # Source: https://www.xmodulo.com/tcp-udp-socket-bash-shell.html
@@ -110,4 +116,4 @@ PORT="$2"
 PASSWORD="$3"
 COMMAND="$4"
 
-rcon-command "$HOST" "$PORT" "$PASSWORD" "$COMMAND"
+rcon-command "$HOST:$PORT:$PASSWORD" "$COMMAND"
diff --git a/test/mock_rcon.py b/test/mock_rcon.py
new file mode 100644
index 0000000..c5f7c35
--- /dev/null
+++ b/test/mock_rcon.py
@@ -0,0 +1,31 @@
+# Reference: https://docs.python.org/3/library/socketserver.html
+import codecs
+import socketserver
+import sys
+
+class Handler(socketserver.BaseRequestHandler):
+    def handle(self):
+        while True:
+            length = int.from_bytes(self.request.recv(4), 'little')
+            if not length:
+                continue
+
+            self.request.recv(4)
+            type_ = int.from_bytes(self.request.recv(4), 'little')
+            self.data = self.request.recv(length - 8)[:-2].decode('utf-8')
+            if self.data:
+                if type_ == 2:
+                    print(self.data)
+                    sys.stdout.flush()
+            try:
+                if type_ == 3 and self.data != sys.argv[2]:
+                    self.request.sendall(codecs.decode('0a000000ffffffff020000000000', 'hex'))
+                else:
+                    self.request.sendall(codecs.decode('0a00000010000000020000000000', 'hex'))
+            except:
+                break
+
+if __name__ == "__main__":
+    HOST, PORT = "localhost", int(sys.argv[1])
+    with socketserver.ThreadingTCPServer((HOST, PORT), Handler) as server:
+        server.serve_forever()
diff --git a/test/test.sh b/test/test.sh
index 7e3e0c9..ae1b0ce 100755
--- a/test/test.sh
+++ b/test/test.sh
@@ -5,6 +5,8 @@
 TEST_DIR="test"
 TEST_TMP="$TEST_DIR/tmp"
 SCREEN_TMP="tmp-screen"
+RCON_PORT="8088"
+RCON_PASSWORD="supersecret"
 setUp () {
   rm -rf "$TEST_TMP"
   mkdir -p "$TEST_TMP/server/world"
@@ -13,6 +15,8 @@ setUp () {
   echo "file2" > "$TEST_TMP/server/world/file2.txt"
   echo "file3" > "$TEST_TMP/server/world/file3.txt"
 
+  python test/mock_rcon.py "$RCON_PORT" "$RCON_PASSWORD" > "$TEST_TMP/rcon-output" &
+  echo "$!" > "$TEST_TMP/rcon-pid"
   screen -dmS "$SCREEN_TMP" bash
   screen -S "$SCREEN_TMP" -X stuff "cat > $TEST_TMP/screen-output\n"
   tmux new-session -d -s "$SCREEN_TMP"
@@ -21,6 +25,8 @@ setUp () {
 }
 
 tearDown () {
+  RCON_PID="$(cat "$TEST_TMP/rcon-pid")"
+  kill "$RCON_PID" >/dev/null 2>&1 || true
   screen -S "$SCREEN_TMP" -X quit >/dev/null 2>&1 || true
   tmux kill-session -t "$SCREEN_TMP" >/dev/null 2>&1 || true
 }
@@ -88,7 +94,7 @@ test-missing-options () {
   OUTPUT="$(./backup.sh 2>&1)"
   EXIT_CODE="$?"
   assertEquals 1 "$EXIT_CODE"
-  assertContains "$OUTPUT" "Minecraft screen name not specified"
+  assertContains "$OUTPUT" "Minecraft screen/tmux/rcon location not specified (use -s)"
   assertContains "$OUTPUT" "Server world not specified"
   assertContains "$OUTPUT" "Backup directory not specified"
 }
@@ -97,7 +103,7 @@ test-missing-options-suppress-warnings () {
   OUTPUT="$(./backup.sh -q 2>&1)"
   EXIT_CODE="$?"
   assertEquals 1 "$EXIT_CODE"
-  assertNotContains "$OUTPUT" "Minecraft screen name not specified"
+  assertNotContains "$OUTPUT" "Minecraft screen/tmux/rcon location not specified (use -s)"
 }
 
 test-empty-world-warning () {
@@ -129,6 +135,20 @@ test-tmux-interface () {
   assertEquals "$SCREEN_CONTENTS" "$EXPECTED_CONTENTS" 
 }
 
+test-rcon-interface () {
+  TIMESTAMP="$(date +%F_%H-%M-%S --date="2021-01-01")"
+  ./backup.sh -w rcon -i "$TEST_TMP/server/world" -o "$TEST_TMP/backups" -s "localhost:$RCON_PORT:$RCON_PASSWORD" -f "$TIMESTAMP"
+  EXPECTED_CONTENTS=$(echo -e "save-off\nsave-on\nsave-all") 
+  SCREEN_CONTENTS="$(head -n3 "$TEST_TMP/rcon-output")"
+  assertEquals "$SCREEN_CONTENTS" "$EXPECTED_CONTENTS" 
+}
+
+test-rcon-interface-wrong-password () {
+  TIMESTAMP="$(date +%F_%H-%M-%S --date="2021-01-01")"
+  OUTPUT="$(./backup.sh -w rcon -i "$TEST_TMP/server/world" -o "$TEST_TMP/backups" -s "localhost:$RCON_PORT:wrong$RCON_PASSWORD" -f "$TIMESTAMP" 2>&1)"
+  assertContains "$OUTPUT" "Wrong RCON password"
+}
+
 test-sequential-delete () {
   for i in $(seq 0 99); do
     TIMESTAMP="$(date +%F_%H-%M-%S --date="2021-01-01 +$i hour")"