Run Capture

1#!/usr/bin/env bash
2# Execute one bounded capture inside the pinned Linux capture image.
3# Exit codes: 0 = success, 1 = capture/archive failure, 2 = invalid configuration.
4set -eu
5
6: "${OUT_DIR:?OUT_DIR is required}"
7: "${CAPTURE_ID:?CAPTURE_ID is required}"
8: "${NODE_NAME:?NODE_NAME is required}"
9: "${RUN_ID:?RUN_ID is required}"
10: "${CAPTURE_DURATION:?CAPTURE_DURATION is required}"
11: "${PACKET_SIZE:?PACKET_SIZE is required}"
12: "${PCAP_FILTER:=}"
13
14case "$CAPTURE_ID" in
15  ""|-*|*-|*[!a-z0-9-]*) echo "invalid CAPTURE_ID" >&2; exit 2 ;;
16esac
17[ "${#CAPTURE_ID}" -le 63 ] || {
18  echo "invalid CAPTURE_ID" >&2
19  exit 2
20}
21case "$NODE_NAME" in
22  ""|*[!A-Za-z0-9._-]*) echo "invalid NODE_NAME" >&2; exit 2 ;;
23esac
24case "$CAPTURE_DURATION" in
25  ""|*[!0-9]*) echo "invalid CAPTURE_DURATION" >&2; exit 2 ;;
26esac
27[ "$CAPTURE_DURATION" -ge 1 ] && [ "$CAPTURE_DURATION" -le 1800 ] || {
28  echo "invalid CAPTURE_DURATION" >&2
29  exit 2
30}
31case "$PACKET_SIZE" in
32  ""|*[!0-9]*) echo "invalid PACKET_SIZE" >&2; exit 2 ;;
33esac
34[ "$PACKET_SIZE" -le 262144 ] || {
35  echo "invalid PACKET_SIZE" >&2
36  exit 2
37}
38
39run_date=${RUN_ID%%-*}
40run_remainder=${RUN_ID#*-}
41run_time=${run_remainder%%-*}
42run_token=${run_remainder#*-}
43[ "${#run_date}" -eq 8 ] && [ "${#run_time}" -eq 6 ] \
44  && [ "${#run_token}" -eq 24 ] || {
45    echo "invalid RUN_ID" >&2
46    exit 2
47  }
48case "${run_date}${run_time}" in
49  *[!0-9]*) echo "invalid RUN_ID" >&2; exit 2 ;;
50esac
51case "$run_token" in
52  *[!0-9a-f]*) echo "invalid RUN_ID" >&2; exit 2 ;;
53esac
54
55PCAP_NAME="capture-${CAPTURE_ID}-${NODE_NAME}-${RUN_ID}.pcap"
56BUNDLE_NAME="capture-${CAPTURE_ID}-${NODE_NAME}-${RUN_ID}.tar.gz"
57PCAP_PATH="${OUT_DIR}/${PCAP_NAME}"
58BUNDLE_PATH="${OUT_DIR}/${BUNDLE_NAME}"
59mkdir -p "$OUT_DIR"
60
61if [ -n "$PCAP_FILTER" ]; then
62  tcpdump -d "$PCAP_FILTER" >/dev/null || {
63    echo "invalid BPF filter" >&2
64    exit 2
65  }
66fi
67
68set -- tcpdump -i any -w "$PCAP_PATH"
69[ "$PACKET_SIZE" -eq 0 ] || set -- "$@" -s "$PACKET_SIZE"
70[ -z "$PCAP_FILTER" ] || set -- "$@" "$PCAP_FILTER"
71
72echo "Capturing for ${CAPTURE_DURATION}s on ${NODE_NAME}"
73if timeout "$CAPTURE_DURATION" "$@"; then
74  capture_status=0
75else
76  capture_status=$?
77fi
78if [ "$capture_status" -ne 0 ] && [ "$capture_status" -ne 124 ]; then
79  echo "tcpdump failed with exit ${capture_status}" >&2
80  exit 1
81fi
82[ -s "$PCAP_PATH" ] || {
83  echo "tcpdump produced no capture file" >&2
84  exit 1
85}
86
87tar -C "$OUT_DIR" -czf "$BUNDLE_PATH" "$PCAP_NAME"
88rm -f "$PCAP_PATH"
89echo "bundle: $BUNDLE_PATH"