mirror of
https://github.com/livekit/livekit.git
synced 2026-07-02 11:22:04 +00:00
David Chen
127 lines
3.7 KiB
Bash
Executable File
127 lines
3.7 KiB
Bash
Executable File
#!/usr/bin/env bash
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# Traffic shaper for the FlexFEC test harness (macOS, dummynet via dnctl/pfctl).
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#
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# Applies packet loss to UDP traffic destined to the SFU's pinned media port on
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# loopback, simulating a robot uplink over cellular: continuous low base loss
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# plus periodic high-loss bursts. Burst on/off transitions are appended to an
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# events file (wall-clock microseconds) so plots can shade the burst windows.
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#
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# Usage:
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# sudo ./shape_macos.sh start --port 7882 --base-loss 0.02 \
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# --burst-loss 0.25 --burst-every 15 --burst-len 3 --events events.csv
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# sudo ./shape_macos.sh stop
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#
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# `start` runs in the foreground until terminated, cleaning up on exit.
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# `stop` force-cleans shaping state from a previous run.
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set -u
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ANCHOR="livekit_fec"
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PIPE=1
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STATE_DIR="${TMPDIR:-/tmp}/livekit_fec_shaper"
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PORT=7882
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BASE_LOSS=0.02
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BURST_LOSS=0.25
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BURST_EVERY=15
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BURST_LEN=3
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EVENTS_FILE=""
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log() { echo "[shape_macos] $*" >&2; }
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now_us() { python3 -c 'import time; print(int(time.time() * 1e6))'; }
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record_event() {
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if [ -n "$EVENTS_FILE" ]; then
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echo "$(now_us),$1" >> "$EVENTS_FILE"
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fi
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}
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cleanup() {
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trap - EXIT INT TERM
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log "cleaning up"
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pfctl -a "$ANCHOR" -F all 2>/dev/null
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# restore the system ruleset, dropping our anchor attachment
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pfctl -f /etc/pf.conf 2>/dev/null
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dnctl -q flush 2>/dev/null
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if [ -f "$STATE_DIR/pf_token" ]; then
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pfctl -X "$(cat "$STATE_DIR/pf_token")" 2>/dev/null
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rm -f "$STATE_DIR/pf_token"
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fi
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record_event "shaper_stopped"
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log "done"
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}
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start() {
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mkdir -p "$STATE_DIR"
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if ! command -v dnctl >/dev/null; then
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log "ERROR: dnctl not found. dummynet is unavailable on this system,"
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log "consider Network Link Conditioner or running the test on Linux."
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exit 1
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fi
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trap cleanup EXIT INT TERM
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# configure the dummynet pipe with the base loss
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dnctl pipe $PIPE config plr "$BASE_LOSS" || { log "dnctl failed"; exit 1; }
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# enable pf, keeping the reference token for clean disable
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local token
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token=$(pfctl -E 2>&1 | awk '/Token/ {print $NF}')
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if [ -n "$token" ]; then
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echo "$token" > "$STATE_DIR/pf_token"
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fi
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# attach our dummynet anchor on top of the system ruleset
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pfctl -q -f - <<EOF
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include "/etc/pf.conf"
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dummynet-anchor "$ANCHOR"
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anchor "$ANCHOR"
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EOF
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# shape UDP packets addressed to the SFU media port (publisher -> SFU leg)
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echo "dummynet in quick proto udp from any to any port $PORT pipe $PIPE" | \
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pfctl -q -a "$ANCHOR" -f -
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log "shaping active: udp dport $PORT, base loss $BASE_LOSS, burst $BURST_LOSS for ${BURST_LEN}s every ${BURST_EVERY}s"
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record_event "shaper_started base=$BASE_LOSS burst=$BURST_LOSS"
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# periodic burst loop
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while true; do
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sleep "$BURST_EVERY"
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dnctl pipe $PIPE config plr "$BURST_LOSS"
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record_event "burst_on"
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log "burst on ($BURST_LOSS)"
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sleep "$BURST_LEN"
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dnctl pipe $PIPE config plr "$BASE_LOSS"
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record_event "burst_off"
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log "burst off ($BASE_LOSS)"
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done
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}
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CMD="${1:-}"
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shift || true
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while [ $# -gt 0 ]; do
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case "$1" in
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--port) PORT="$2"; shift 2 ;;
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--base-loss) BASE_LOSS="$2"; shift 2 ;;
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--burst-loss) BURST_LOSS="$2"; shift 2 ;;
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--burst-every) BURST_EVERY="$2"; shift 2 ;;
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--burst-len) BURST_LEN="$2"; shift 2 ;;
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--events) EVENTS_FILE="$2"; shift 2 ;;
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*) log "unknown argument: $1"; exit 1 ;;
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esac
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done
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if [ "$(id -u)" -ne 0 ]; then
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log "ERROR: must run as root (sudo)"
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exit 1
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fi
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case "$CMD" in
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start) start ;;
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stop) cleanup ;;
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*) echo "usage: $0 {start|stop} [--port N] [--base-loss F] [--burst-loss F] [--burst-every S] [--burst-len S] [--events FILE]" >&2; exit 1 ;;
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esac
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