46 lines
1.8 KiB
Plaintext
46 lines
1.8 KiB
Plaintext
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#!/bin/sh
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# Revoke the PPPoE dial lease. Runs every 5s. Only ever takes the WAN AWAY.
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#
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# vrrp-wan-reconcile is the single writer and runs every 30s; this is the
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# watcher, and it exists because `may-dial` must be a LEASE, not a flag.
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# ConditionPathExists is evaluated at START only -- it can prevent a dial, it can
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# never revoke one. So if the reconciler stops running (timer masked, box wedged,
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# someone stops it during maintenance) and the box is then demoted, nothing would
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# ever hang up: it would keep the one ISP session while the new master tries to
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# take it.
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#
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# Two conditions revoke, both biased the safe way:
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# - this box does not hold the management VIP
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# - the lease has not been renewed within LEASE_TTL (the reconciler is dead)
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#
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# Deliberately tiny: no config mode, no flock, no commit. It cannot wedge the
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# router's configuration system, which is what earns it a 5s timer. Running at
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# 5s rather than the reconciler's 30s is also what shrinks the double-dial
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# window on a demotion from up to 30s down to about 5.
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CONF=/config/vrrp-wan.conf
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[ -r "$CONF" ] && . "$CONF"
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VIP="${VRRP_WAN_VIP:-192.168.1.1}"
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LEASE_TTL="${LEASE_TTL:-75}"
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STATE=/run/vrrp-wan
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revoke() {
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rm -f "$STATE/may-dial"
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systemctl is-active --quiet ppp@pppoe0 2>/dev/null || return 0
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logger -t vrrp-wan "GUARD: $1 -- hanging up pppoe0"
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systemctl stop ppp@pppoe0 2>/dev/null
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}
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if ! ip -4 -o addr show 2>/dev/null | grep -q " ${VIP}/"; then
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revoke "does not hold ${VIP}"
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exit 0
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fi
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# Holds the VIP, so it is entitled to dial -- but only while something is
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# actively renewing the lease on its behalf.
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if [ -f "$STATE/may-dial" ]; then
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age=$(( $(date +%s) - $(stat -c %Y "$STATE/may-dial" 2>/dev/null || echo 0) ))
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[ "$age" -gt "$LEASE_TTL" ] && revoke "lease stale (${age}s > ${LEASE_TTL}s; is vrrp-wan-reconcile.timer running?)"
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fi
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exit 0
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