196 lines
6.9 KiB
Bash
Executable file
196 lines
6.9 KiB
Bash
Executable file
#!/usr/bin/env bash
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set -Eeuo pipefail
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IFS=$'\n\t'
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export LC_ALL=C
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umask 077
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readonly TABLE_FAMILY="inet"
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readonly TABLE_NAME="ochenstarik_smm"
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readonly CHAIN_NAME="links"
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fail() { printf '%s\n' "policy helper: $*" >&2; exit 78; }
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firewall_unavailable() { printf '%s\n' "mesh.firewall-unavailable" >&2; exit 79; }
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testing="${SMM_POLICY_TESTING:-0}"
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if [[ "$testing" != "1" ]]; then
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[[ ${EUID:-$(id -u)} -eq 0 ]] || fail "root is required"
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readonly STATE_FILE="/var/lib/ochenstarik-server-monitor-manager/mesh/nodes.tsv"
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readonly RECONCILE_MARKER="/var/lib/ochenstarik-server-monitor-manager/mesh/reconcile-requested"
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readonly RECONCILE_LOCK="/var/lib/ochenstarik-server-monitor-manager/mesh/reconcile-requested.lock"
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readonly FLOCK_COMMAND="/usr/bin/flock"
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else
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readonly STATE_FILE="${SMM_POLICY_STATE_FILE:-/dev/null}"
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readonly RECONCILE_MARKER="${SMM_POLICY_RECONCILE_MARKER:-${TMPDIR:-/tmp}/smm-policy-reconcile-requested}"
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readonly RECONCILE_LOCK="${SMM_POLICY_RECONCILE_LOCK:-${RECONCILE_MARKER}.lock}"
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readonly FLOCK_COMMAND="${SMM_POLICY_FLOCK:-/usr/bin/flock}"
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fi
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node_pattern='^[a-z0-9]([a-z0-9-]{0,61}[a-z0-9])?$'
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ipv4_pattern='^([0-9]{1,3}\.){3}[0-9]{1,3}$'
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generation_pattern='^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$'
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validate_node_id() {
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[[ "$1" =~ $node_pattern ]] || fail "invalid node id"
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}
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lookup_node_ip() {
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local node_id="$1" ip
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[[ -r "$STATE_FILE" ]] || fail "mesh node state is unavailable"
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ip="$(awk -F '\t' -v node="$node_id" '$1 == node { print $2; exit }' "$STATE_FILE")"
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[[ "$ip" =~ $ipv4_pattern ]] || fail "node has no valid mesh address: $node_id"
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printf '%s\n' "$ip"
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}
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validate_rule() {
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local action="$1"
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case "$action" in
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link-connect) [[ $# -eq 6 ]] || fail "invalid link-connect argument count" ;;
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link-disconnect) [[ $# -eq 5 ]] || fail "invalid link-disconnect argument count" ;;
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link-status) [[ $# -eq 5 ]] || fail "invalid link-status argument count" ;;
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*) fail "unsupported action" ;;
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esac
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validate_node_id "$2"
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validate_node_id "$3"
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[[ "$2" != "$3" ]] || fail "source and destination must differ"
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[[ "$4" == "tcp" || "$4" == "udp" ]] || fail "invalid protocol"
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[[ "$5" =~ ^[0-9]+$ ]] && (( 10#$5 >= 1 && 10#$5 <= 65535 )) || fail "invalid port"
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if [[ "$action" == "link-connect" ]]; then
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[[ "$6" =~ ^[0-9]+$ ]] && (( 10#$6 >= 0 && 10#$6 <= 525600 )) || fail "invalid TTL"
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fi
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}
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run_nft() {
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if [[ "$testing" == "1" ]]; then
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printf 'nft'
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printf ' %q' "$@"
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printf '\n'
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else
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/usr/sbin/nft "$@"
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fi
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}
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inspect_firewall() {
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local listing
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if [[ "$testing" == "1" ]]; then
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[[ "${SMM_POLICY_FIREWALL_UNAVAILABLE:-0}" != "1" ]] || firewall_unavailable
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[[ -z "${SMM_POLICY_FIREWALL_ERROR:-}" ]] \
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|| fail "could not inspect nftables Link policy: $SMM_POLICY_FIREWALL_ERROR"
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return 0
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fi
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if listing="$(/usr/sbin/nft -a list chain "$TABLE_FAMILY" "$TABLE_NAME" "$CHAIN_NAME" 2>&1)"; then
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printf '%s\n' "$listing"
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return 0
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fi
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if grep -Eiq 'No such file or directory|does not exist' <<<"$listing"; then
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firewall_unavailable
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fi
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fail "could not inspect nftables Link policy: ${listing%%$'\n'*}"
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}
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ensure_firewall_available() {
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inspect_firewall >/dev/null
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}
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rule_exists() {
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local comment="$1" listing
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listing="$(inspect_firewall)"
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grep -Fq "comment \"$comment\"" <<<"$listing"
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}
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connect_rule() {
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local source_id="$1" target_id="$2" protocol="$3" port="$4"
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local source_ip target_ip comment
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ensure_firewall_available
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source_ip="$(lookup_node_ip "$source_id")"
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target_ip="$(lookup_node_ip "$target_id")"
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comment="smm:${source_id}:${target_id}:${protocol}:${port}"
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rule_exists "$comment" && return 0
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run_nft add rule "$TABLE_FAMILY" "$TABLE_NAME" "$CHAIN_NAME" \
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ip saddr "$source_ip" ip daddr "$target_ip" "$protocol" dport "$port" \
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counter accept comment "$comment"
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}
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disconnect_rule() {
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local source_id="$1" target_id="$2" protocol="$3" port="$4" comment handle
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ensure_firewall_available
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# Resolve both identities before touching firewall state.
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lookup_node_ip "$source_id" >/dev/null
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lookup_node_ip "$target_id" >/dev/null
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comment="smm:${source_id}:${target_id}:${protocol}:${port}"
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if [[ "$testing" == "1" ]]; then
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printf 'nft-delete-comment %q\n' "$comment"
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return
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fi
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while IFS= read -r handle; do
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[[ "$handle" =~ ^[0-9]+$ ]] || continue
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run_nft delete rule "$TABLE_FAMILY" "$TABLE_NAME" "$CHAIN_NAME" handle "$handle"
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done < <(
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/usr/sbin/nft -a list chain "$TABLE_FAMILY" "$TABLE_NAME" "$CHAIN_NAME" \
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| grep -F "comment \"$comment\"" \
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| sed -n 's/.* # handle \([0-9][0-9]*\)$/\1/p'
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)
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}
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status_rule() {
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local source_id="$1" target_id="$2" protocol="$3" port="$4" comment
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ensure_firewall_available
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# A status is meaningful only for identities currently known to the mesh.
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lookup_node_ip "$source_id" >/dev/null
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lookup_node_ip "$target_id" >/dev/null
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comment="smm:${source_id}:${target_id}:${protocol}:${port}"
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if rule_exists "$comment"; then
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printf '%s\n' active
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else
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printf '%s\n' disabled
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fi
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}
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reconcile_status() {
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local generation
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exec 9>"$RECONCILE_LOCK"
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chmod 0600 "$RECONCILE_LOCK"
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"$FLOCK_COMMAND" -x 9
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if [[ ! -f "$RECONCILE_MARKER" ]]; then
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printf '%s\n' complete
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return
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fi
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IFS= read -r generation <"$RECONCILE_MARKER" || fail "invalid reconciliation marker"
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[[ "$generation" =~ $generation_pattern ]] || fail "invalid reconciliation marker"
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printf 'requested:%s\n' "$generation"
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}
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reconcile_complete() {
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local expected_generation="$1" current_generation=''
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[[ "$expected_generation" =~ $generation_pattern ]] || fail "invalid reconciliation generation"
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exec 9>"$RECONCILE_LOCK"
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chmod 0600 "$RECONCILE_LOCK"
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"$FLOCK_COMMAND" -x 9
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if [[ -f "$RECONCILE_MARKER" ]]; then
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IFS= read -r current_generation <"$RECONCILE_MARKER" || fail "invalid reconciliation marker"
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[[ "$current_generation" =~ $generation_pattern ]] || fail "invalid reconciliation marker"
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if [[ "$current_generation" == "$expected_generation" ]]; then
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rm -f -- "$RECONCILE_MARKER"
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fi
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fi
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printf '%s\n' complete
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}
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action="${1:-}"
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case "$action" in
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reconcile-status)
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[[ $# -eq 1 ]] || fail "invalid reconcile-status argument count"
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reconcile_status
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exit 0
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;;
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reconcile-complete)
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[[ $# -eq 2 ]] || fail "invalid reconcile-complete argument count"
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reconcile_complete "$2"
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exit 0
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;;
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esac
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validate_rule "$@"
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case "$action" in
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link-connect) connect_rule "$2" "$3" "$4" "$5" ;;
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link-disconnect) disconnect_rule "$2" "$3" "$4" "$5" ;;
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link-status) status_rule "$2" "$3" "$4" "$5" ;;
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esac
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