532 lines
15 KiB
Bash
532 lines
15 KiB
Bash
#!/bin/bash
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#
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# Network watchdog for the CUPS print server.
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# Default behavior: when connectivity checks fail repeatedly, switch the
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# configured interface back to DHCP so the box can regain network access.
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# If DHCP reveals a different gateway, the script can rebuild the static IP
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# with the new network prefix while keeping the old host octet.
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#
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# Edit /etc/cups-watchdog/network-watchdog.conf to set STATIC_IP,
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# STATIC_PREFIX, STATIC_GATEWAY and STATIC_DNS. You can also run:
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# /opt/cups-watchdog/network-watchdog.sh static
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# /opt/cups-watchdog/network-watchdog.sh dhcp
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#
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set -u
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CONFIG_FILE="${CUPS_NETWORK_WATCHDOG_CONFIG:-/etc/cups-watchdog/network-watchdog.conf}"
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STATE_DIR="/run/cups-watchdog"
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INTERFACE=""
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STATIC_IP=""
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STATIC_PREFIX="24"
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STATIC_GATEWAY=""
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STATIC_DNS="114.114.114.114 223.5.5.5"
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STATIC_HOST_OCTET=""
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PING_TARGETS="223.5.5.5 114.114.114.114"
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FAIL_THRESHOLD=3
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DHCP_AFTER_FAILURE=1
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REBASE_STATIC_ON_GATEWAY_CHANGE=1
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REBASE_WAIT_SECONDS=20
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LOG_FILE="/var/log/cups-watchdog/network.log"
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MAX_LOG_SIZE_KB=256
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if [ -f "$CONFIG_FILE" ]; then
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# shellcheck disable=SC1090
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. "$CONFIG_FILE"
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fi
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mkdir -p "$STATE_DIR"
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mkdir -p "$(dirname "$LOG_FILE")" 2>/dev/null || true
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acquire_lock() {
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local lock_dir="$STATE_DIR/network.lock"
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if ! mkdir "$lock_dir" 2>/dev/null; then
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echo "$(date '+%Y-%m-%d %H:%M:%S') [network-watchdog] another run is active"
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exit 0
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fi
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trap 'rmdir "$lock_dir" 2>/dev/null || true' EXIT
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}
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rotate_log() {
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local max_bytes=$((MAX_LOG_SIZE_KB * 1024))
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if [ -f "$LOG_FILE" ] && [ "$(wc -c < "$LOG_FILE" 2>/dev/null || echo 0)" -gt "$max_bytes" ]; then
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mv "$LOG_FILE" "$LOG_FILE.1" 2>/dev/null || true
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: > "$LOG_FILE"
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fi
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}
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log_msg() {
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local msg="$1"
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local line
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rotate_log
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line="$(date '+%Y-%m-%d %H:%M:%S') [network-watchdog] $msg"
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echo "$line"
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echo "$line" >> "$LOG_FILE" 2>/dev/null || true
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}
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detect_interface() {
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if [ -n "${INTERFACE:-}" ] && ip link show "$INTERFACE" >/dev/null 2>&1; then
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echo "$INTERFACE"
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return 0
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fi
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ip route show default 2>/dev/null | awk '{print $5; exit}'
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}
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current_ipv4_for_interface() {
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local iface="$1"
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ip -4 -o addr show dev "$iface" scope global 2>/dev/null | awk '{split($4, a, "/"); print a[1]; exit}'
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}
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current_prefix_for_interface() {
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local iface="$1"
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ip -4 -o addr show dev "$iface" scope global 2>/dev/null | awk '{split($4, a, "/"); print a[2]; exit}'
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}
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current_gateway_for_interface() {
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local iface="$1"
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local gateway
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gateway="$(ip route show default dev "$iface" 2>/dev/null | awk '{print $3; exit}')"
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if [ -z "$gateway" ]; then
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gateway="$(ip route show default 2>/dev/null | awk '{print $3; exit}')"
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fi
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echo "$gateway"
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}
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last_octet() {
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local ip="$1"
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case "$ip" in
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*.*.*.*) echo "${ip##*.}" ;;
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*) echo "" ;;
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esac
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}
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prefix24() {
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local ip="$1"
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case "$ip" in
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*.*.*.*) echo "${ip%.*}" ;;
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*) echo "" ;;
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esac
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}
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valid_host_octet() {
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local octet="$1"
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case "$octet" in
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''|*[!0-9]*) return 1 ;;
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esac
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[ "$octet" -ge 1 ] 2>/dev/null && [ "$octet" -le 254 ] 2>/dev/null
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}
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nm_connection_for_interface() {
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local iface="$1"
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nmcli -t -f NAME,DEVICE con show --active 2>/dev/null | awk -F: -v iface="$iface" '$2 == iface {print $1; exit}'
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}
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configure_dhcp_nmcli() {
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local iface="$1"
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local conn
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conn="$(nm_connection_for_interface "$iface")"
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[ -n "$conn" ] || conn="$iface"
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nmcli con mod "$conn" ipv4.method auto ipv4.addresses "" ipv4.gateway "" ipv4.dns "" >/dev/null
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nmcli con down "$conn" >/dev/null 2>&1 || true
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nmcli con up "$conn" >/dev/null
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}
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configure_dhcp_netplan() {
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local iface="$1"
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local target_file="/etc/netplan/99-cups-watchdog-dhcp.yaml"
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cat > "$target_file" << EOF
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# DHCP recovery config generated by cups network watchdog.
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network:
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version: 2
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renderer: networkd
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ethernets:
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$iface:
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dhcp4: yes
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EOF
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chmod 600 "$target_file"
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rm -f /etc/netplan/01-static-ip.yaml /etc/netplan/99-cups-static-ip.yaml /etc/netplan/99-cups-watchdog-static.yaml 2>/dev/null || true
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netplan apply
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}
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configure_dhcp_interfaces() {
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local iface="$1"
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if [ -f /etc/network/interfaces ]; then
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cp /etc/network/interfaces /etc/network/interfaces.cups-watchdog.bak
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fi
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cat > /etc/network/interfaces << EOF
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# DHCP recovery config generated by cups network watchdog.
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auto lo
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iface lo inet loopback
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auto $iface
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iface $iface inet dhcp
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EOF
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systemctl restart networking 2>/dev/null || /etc/init.d/networking restart 2>/dev/null || true
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}
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configure_dhcp() {
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local iface
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iface="$(detect_interface)"
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if [ -z "$iface" ]; then
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log_msg "cannot switch to DHCP: network interface not found"
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return 1
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fi
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log_msg "switching $iface to DHCP"
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if command -v nmcli >/dev/null 2>&1 && systemctl is-active --quiet NetworkManager 2>/dev/null; then
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configure_dhcp_nmcli "$iface"
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elif [ -d /etc/netplan ] && command -v netplan >/dev/null 2>&1; then
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configure_dhcp_netplan "$iface"
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else
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configure_dhcp_interfaces "$iface"
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fi
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}
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set_config_value() {
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local key="$1"
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local value="$2"
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local tmp_file
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if [ ! -f "$CONFIG_FILE" ]; then
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mkdir -p "$(dirname "$CONFIG_FILE")" 2>/dev/null || true
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: > "$CONFIG_FILE" 2>/dev/null || return 1
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fi
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tmp_file="${CONFIG_FILE}.tmp.$$"
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if grep -q "^${key}=" "$CONFIG_FILE" 2>/dev/null; then
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awk -v key="$key" -v value="$value" '
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BEGIN { q = sprintf("%c", 34) }
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$0 ~ "^" key "=" { print key "=" q value q; next }
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{ print }
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' "$CONFIG_FILE" > "$tmp_file" && mv "$tmp_file" "$CONFIG_FILE"
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else
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printf '%s="%s"\n' "$key" "$value" >> "$CONFIG_FILE"
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fi
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chmod 600 "$CONFIG_FILE" 2>/dev/null || true
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}
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wait_for_dhcp_network() {
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local iface="$1"
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local i=0
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local ip
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local gateway
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while [ "$i" -lt "${REBASE_WAIT_SECONDS:-20}" ]; do
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ip="$(current_ipv4_for_interface "$iface")"
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gateway="$(current_gateway_for_interface "$iface")"
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if [ -n "$ip" ] && [ -n "$gateway" ]; then
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echo "$ip $gateway"
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return 0
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fi
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i=$((i + 1))
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sleep 1
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done
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return 1
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}
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candidate_ip_in_use() {
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local iface="$1"
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local candidate_ip="$2"
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local current_ip="$3"
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[ "$candidate_ip" = "$current_ip" ] && return 1
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if command -v arping >/dev/null 2>&1; then
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# arping duplicate-address detection returns success when no reply is seen.
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arping -D -I "$iface" -c 2 -w 3 "$candidate_ip" >/dev/null 2>&1
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[ "$?" != "0" ] && return 0
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return 1
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fi
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if ping -c 1 -W 1 "$candidate_ip" >/dev/null 2>&1; then
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return 0
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fi
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return 1
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}
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configure_static_nmcli() {
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local iface="$1"
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local conn
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conn="$(nm_connection_for_interface "$iface")"
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[ -n "$conn" ] || conn="$iface"
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nmcli con mod "$conn" ipv4.method manual ipv4.addresses "$STATIC_IP/$STATIC_PREFIX" ipv4.gateway "$STATIC_GATEWAY" ipv4.dns "$STATIC_DNS" >/dev/null
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nmcli con down "$conn" >/dev/null 2>&1 || true
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nmcli con up "$conn" >/dev/null
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}
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configure_static_netplan() {
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local iface="$1"
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local target_file="/etc/netplan/99-cups-watchdog-static.yaml"
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local dns_list=""
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local d
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for d in $STATIC_DNS; do
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dns_list="$dns_list, $d"
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done
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dns_list="${dns_list#, }"
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cat > "$target_file" << EOF
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# Static network config generated by cups network watchdog.
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network:
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version: 2
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renderer: networkd
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ethernets:
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$iface:
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dhcp4: no
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addresses:
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- $STATIC_IP/$STATIC_PREFIX
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routes:
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- to: default
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via: $STATIC_GATEWAY
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nameservers:
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addresses: [$dns_list]
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EOF
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chmod 600 "$target_file"
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rm -f /etc/netplan/01-dhcp.yaml /etc/netplan/99-cups-dhcp.yaml /etc/netplan/99-cups-watchdog-dhcp.yaml 2>/dev/null || true
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netplan apply
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}
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configure_static_interfaces() {
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local iface="$1"
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local netmask="255.255.255.0"
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case "$STATIC_PREFIX" in
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8) netmask="255.0.0.0" ;;
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16) netmask="255.255.0.0" ;;
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24) netmask="255.255.255.0" ;;
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25) netmask="255.255.255.128" ;;
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26) netmask="255.255.255.192" ;;
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27) netmask="255.255.255.224" ;;
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28) netmask="255.255.255.240" ;;
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29) netmask="255.255.255.248" ;;
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30) netmask="255.255.255.252" ;;
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esac
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if [ -f /etc/network/interfaces ]; then
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cp /etc/network/interfaces /etc/network/interfaces.cups-watchdog.bak
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fi
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cat > /etc/network/interfaces << EOF
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# Static network config generated by cups network watchdog.
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auto lo
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iface lo inet loopback
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auto $iface
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iface $iface inet static
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address $STATIC_IP
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netmask $netmask
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gateway $STATIC_GATEWAY
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dns-nameservers $STATIC_DNS
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EOF
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systemctl restart networking 2>/dev/null || /etc/init.d/networking restart 2>/dev/null || true
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}
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configure_static() {
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local iface
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iface="$(detect_interface)"
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if [ -z "$iface" ]; then
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log_msg "cannot switch to static: network interface not found"
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return 1
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fi
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if [ -z "${STATIC_IP:-}" ] || [ -z "${STATIC_GATEWAY:-}" ]; then
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log_msg "cannot switch to static: STATIC_IP or STATIC_GATEWAY is empty in $CONFIG_FILE"
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return 1
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fi
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log_msg "switching $iface to static $STATIC_IP/$STATIC_PREFIX"
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if command -v nmcli >/dev/null 2>&1 && systemctl is-active --quiet NetworkManager 2>/dev/null; then
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configure_static_nmcli "$iface"
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elif [ -d /etc/netplan ] && command -v netplan >/dev/null 2>&1; then
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configure_static_netplan "$iface"
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else
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configure_static_interfaces "$iface"
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fi
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}
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rebase_static_after_dhcp() {
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local iface="$1"
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local dhcp_state
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local dhcp_ip
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local dhcp_gateway
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local dhcp_prefix
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local host_octet
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local base_prefix
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local candidate_ip
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local old_static_ip="$STATIC_IP"
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local old_static_gateway="$STATIC_GATEWAY"
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local old_static_prefix="$STATIC_PREFIX"
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local old_static_dns="$STATIC_DNS"
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local current_dns
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[ "${REBASE_STATIC_ON_GATEWAY_CHANGE:-1}" = "1" ] || return 0
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if [ -z "${STATIC_IP:-}" ] || [ -z "${STATIC_GATEWAY:-}" ]; then
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log_msg "skip static rebase: STATIC_IP or STATIC_GATEWAY is empty"
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return 0
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fi
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dhcp_state="$(wait_for_dhcp_network "$iface" 2>/dev/null || true)"
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if [ -z "$dhcp_state" ]; then
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log_msg "skip static rebase: DHCP did not provide an IP and gateway in time"
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return 0
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fi
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dhcp_ip="$(echo "$dhcp_state" | awk '{print $1}')"
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dhcp_gateway="$(echo "$dhcp_state" | awk '{print $2}')"
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if [ "$dhcp_gateway" = "$STATIC_GATEWAY" ]; then
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log_msg "DHCP gateway is still $dhcp_gateway; keep DHCP recovery without rebasing static IP"
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return 0
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fi
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host_octet="${STATIC_HOST_OCTET:-$(last_octet "$STATIC_IP")}"
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if ! valid_host_octet "$host_octet"; then
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log_msg "skip static rebase: invalid STATIC_HOST_OCTET '$host_octet'"
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return 0
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fi
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base_prefix="$(prefix24 "$dhcp_ip")"
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[ -n "$base_prefix" ] || base_prefix="$(prefix24 "$dhcp_gateway")"
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if [ -z "$base_prefix" ]; then
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log_msg "skip static rebase: cannot derive IPv4 /24 prefix from DHCP state"
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return 0
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fi
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candidate_ip="${base_prefix}.${host_octet}"
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if candidate_ip_in_use "$iface" "$candidate_ip" "$dhcp_ip"; then
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log_msg "skip static rebase: candidate $candidate_ip appears to be in use; staying on DHCP"
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return 0
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fi
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dhcp_prefix="$(current_prefix_for_interface "$iface")"
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STATIC_IP="$candidate_ip"
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STATIC_GATEWAY="$dhcp_gateway"
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STATIC_PREFIX="${dhcp_prefix:-$STATIC_PREFIX}"
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current_dns="$(grep -E '^nameserver ' /etc/resolv.conf 2>/dev/null | awk '{print $2}' | head -n2 | tr '\n' ' ')"
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STATIC_DNS="${current_dns:-$STATIC_DNS}"
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log_msg "gateway changed from $old_static_gateway to $STATIC_GATEWAY; rebasing static IP from $old_static_ip to $STATIC_IP/$STATIC_PREFIX"
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configure_static
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sleep 3
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if connectivity_ok; then
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set_config_value "STATIC_IP" "$STATIC_IP" || true
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set_config_value "STATIC_GATEWAY" "$STATIC_GATEWAY" || true
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set_config_value "STATIC_PREFIX" "$STATIC_PREFIX" || true
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set_config_value "STATIC_DNS" "$STATIC_DNS" || true
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set_config_value "STATIC_HOST_OCTET" "$host_octet" || true
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set_config_value "PING_TARGETS" "$STATIC_GATEWAY 223.5.5.5 114.114.114.114" || true
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log_msg "static rebase succeeded: $STATIC_IP via $STATIC_GATEWAY"
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return 0
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fi
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STATIC_IP="$old_static_ip"
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STATIC_GATEWAY="$old_static_gateway"
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STATIC_PREFIX="$old_static_prefix"
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STATIC_DNS="$old_static_dns"
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log_msg "static rebase to $candidate_ip failed connectivity check; falling back to DHCP"
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configure_dhcp
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}
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recover_after_failure() {
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local iface
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local fallback_iface
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fallback_iface="$(detect_interface)"
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configure_dhcp || return 1
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iface="$(detect_interface)"
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[ -n "$iface" ] || iface="$fallback_iface"
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if [ -z "$iface" ]; then
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log_msg "skip static rebase: network interface not found after DHCP recovery"
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return 1
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fi
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rebase_static_after_dhcp "$iface"
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}
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connectivity_ok() {
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local iface
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local gateway
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local target
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iface="$(detect_interface)"
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if [ -n "$iface" ] && [ -f "/sys/class/net/$iface/carrier" ]; then
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if [ "$(cat "/sys/class/net/$iface/carrier" 2>/dev/null || echo 0)" != "1" ]; then
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return 1
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fi
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fi
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gateway="$(ip route show default 2>/dev/null | awk '{print $3; exit}')"
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if [ -n "$gateway" ] && ping -c 1 -W 2 "$gateway" >/dev/null 2>&1; then
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return 0
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fi
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for target in $PING_TARGETS; do
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[ -n "$target" ] || continue
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if ping -c 1 -W 2 "$target" >/dev/null 2>&1; then
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return 0
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fi
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done
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return 1
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}
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check_network() {
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local count_file="$STATE_DIR/network.fail_count"
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local fail_count=0
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if connectivity_ok; then
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echo 0 > "$count_file"
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log_msg "connectivity ok"
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return 0
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fi
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if [ -f "$count_file" ]; then
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fail_count="$(cat "$count_file" 2>/dev/null || echo 0)"
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fi
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fail_count=$((fail_count + 1))
|
|
echo "$fail_count" > "$count_file"
|
|
|
|
log_msg "connectivity failed ($fail_count/$FAIL_THRESHOLD)"
|
|
if [ "$fail_count" -ge "$FAIL_THRESHOLD" ] && [ "$DHCP_AFTER_FAILURE" = "1" ]; then
|
|
recover_after_failure
|
|
echo 0 > "$count_file"
|
|
fi
|
|
}
|
|
|
|
case "${1:-check}" in
|
|
check)
|
|
acquire_lock
|
|
check_network
|
|
;;
|
|
dhcp)
|
|
acquire_lock
|
|
configure_dhcp
|
|
;;
|
|
static)
|
|
acquire_lock
|
|
configure_static
|
|
;;
|
|
*)
|
|
echo "Usage: $0 [check|dhcp|static]"
|
|
exit 2
|
|
;;
|
|
esac
|