Update fallback-ap.sh

Reviewed-on: #12

fallback-ap.sh

@@ -3,16 +3,34 @@
 set -e
 
 # Configuration =======================================================================================================
+#
+# Connection settings (SSID, passphrase, subnet, DHCP range, interface) can
+# be supplied three ways, highest priority first:
+#   1. Environment variables (FALLBACK_AP_*) - used for headless installs.
+#   2. The persisted config file below, written by `install`.
+#   3. The hard-coded defaults in this block.
+#
+# Everything else (timers, paths) is not meant to be reconfigured per-install
+# and stays as plain constants.
 
-WLAN0_IFACE="wlan0"
+CONFIG_FILE="/etc/fallback-ap.conf"
+if [ -f "$CONFIG_FILE" ]; then source "$CONFIG_FILE"; fi
 
-AP_NAME="${HOSTNAME}"
-AP_PASSWORD='guesswhatitis'
-AP_ENCRYPTION="wpa-psk" # none | wpa-psk | sae
+WLAN0_IFACE="${FALLBACK_AP_IFACE:-${SAVED_IFACE:-wlan0}}"
 
-AP_CIDR="10.10.10.1/24"
-DHCP_START="10.10.10.100"
-DHCP_END="10.10.10.250"
+AP_NAME="${FALLBACK_AP_SSID:-${SAVED_SSID:-$HOSTNAME}}"
+AP_PASSWORD="${FALLBACK_AP_PASSWORD:-${SAVED_PASSWORD:-abcd1234}}"
+AP_ENCRYPTION="${FALLBACK_AP_ENCRYPTION:-${SAVED_ENCRYPTION:-wpa-psk}}" # none | wpa-psk | sae
+
+FALLBACK_AP_CIDR="${FALLBACK_AP_CIDR:-${SAVED_CIDR:-10.10.10.1/24}}"
+FALLBACK_AP_DHCP_START_OCTET="${FALLBACK_AP_DHCP_START_OCTET:-${SAVED_DHCP_START_OCTET:-100}}"
+FALLBACK_AP_DHCP_END_OCTET="${FALLBACK_AP_DHCP_END_OCTET:-${SAVED_DHCP_END_OCTET:-250}}"
+
+AP_CIDR="$FALLBACK_AP_CIDR"
+AP_NETWORK_BASE="${AP_CIDR%%/*}"   # e.g. "10.10.10.1" out of "10.10.10.1/24"
+AP_NETWORK_BASE="${AP_NETWORK_BASE%.*}" # e.g. "10.10.10"
+DHCP_START="${AP_NETWORK_BASE}.${FALLBACK_AP_DHCP_START_OCTET}"
+DHCP_END="${AP_NETWORK_BASE}.${FALLBACK_AP_DHCP_END_OCTET}"
 
 # How often, while the AP has no clients, to stop the AP and give
 # NetworkManager a chance to reconnect to a known Wi-Fi network.
@@ -27,10 +45,10 @@ RECOVERY_WINDOW=20
 STATE_SETTLE_DELAY=1
 
 CONNECTION_NAME="Fallback AP"
-SERVICE_NAME="pi-fallback-ap"
+SERVICE_NAME="fallback-ap"
 SERVICE_FILE="/etc/systemd/system/$SERVICE_NAME.service"
 
-STATE_DIR="/var/lib/pi-fallback-ap"
+STATE_DIR="/var/lib/fallback-ap"
 LAST_WIFI_FILE="$STATE_DIR/last-wifi"
 LOCK_FILE="$STATE_DIR/lock"
 STATE_FILE="$STATE_DIR/state"
@@ -189,16 +207,6 @@ stop_ap() {
     return 0
 }
 
-
-# ==========================================================================
-# One tick of the control loop. Called once per second, always while
-# holding the wlan0 lock, so everything here runs to completion before
-# the next tick starts - there is no interleaving to race against.
-#
-# `last_attempt` is intentionally not declared `local` here: it lives in
-# run()'s scope and this function updates it directly (bash resolves it
-# via the caller's scope as long as nothing else shadows it).
-# ==========================================================================
 tick() {
     local now="$1"
 
@@ -227,8 +235,6 @@ tick() {
     clients="$(get_client_count)"
 
     if [ "$clients" -gt 0 ]; then
-        # Someone is using the AP right now. Leave it alone and push the
-        # next recovery attempt back so we don't kick them off.
         last_attempt="$now"
         return
     fi
@@ -239,9 +245,6 @@ tick() {
     fi
 }
 
-
-# Stop the AP, give NetworkManager a window to autoconnect to any known
-# network it can see, and bring the AP back if that doesn't happen.
 attempt_recovery() {
     log "No AP clients, checking for known Wi-Fi (AP down for up to ${RECOVERY_WINDOW}s)"
 
@@ -276,6 +279,21 @@ attempt_recovery() {
 }
 
 
+save_config() {
+    mkdir -p "$(dirname "$CONFIG_FILE")"
+    cat > "$CONFIG_FILE" <<EOF
+SAVED_IFACE="$WLAN0_IFACE"
+SAVED_SSID="$AP_NAME"
+SAVED_PASSWORD="$AP_PASSWORD"
+SAVED_ENCRYPTION="$AP_ENCRYPTION"
+SAVED_CIDR="$FALLBACK_AP_CIDR"
+SAVED_DHCP_START_OCTET="$FALLBACK_AP_DHCP_START_OCTET"
+SAVED_DHCP_END_OCTET="$FALLBACK_AP_DHCP_END_OCTET"
+EOF
+    chmod 600 "$CONFIG_FILE"
+}
+
+
 install() {
     if [ "$EUID" -ne 0 ]; then
         echo "Run this script as root."
@@ -297,6 +315,7 @@ install() {
     fi
 
     create_connection
+    save_config
 
     log "Creating recovery service"
 
@@ -324,6 +343,7 @@ EOF
 
     log "Installation complete"
     log "Script: $SCRIPT_PATH"
+    log "Config file: $CONFIG_FILE"
     log "SSID: $AP_NAME"
     log "Interface: $WLAN0_IFACE"
     log "Network: $AP_CIDR"
@@ -411,6 +431,7 @@ uninstall() {
     nmcli connection delete "$CONNECTION_NAME" >/dev/null 2>&1 || true
 
     rm -f "$SERVICE_FILE"
+    rm -f "$CONFIG_FILE"
     rm -rf "$STATE_DIR"
 
     systemctl daemon-reload
@@ -460,6 +481,13 @@ status() {
     echo "=== Fallback AP ==="
     nmcli connection show "$CONNECTION_NAME" 2>/dev/null || echo "Not installed"
 
+    echo
+    echo "=== Config ($CONFIG_FILE) ==="
+    echo "SSID: $AP_NAME"
+    echo "Interface: $WLAN0_IFACE"
+    echo "Network: $AP_CIDR"
+    echo "DHCP: $DHCP_START - $DHCP_END"
+
     echo
     echo "=== Last Known Wi-Fi ==="
     get_last_wifi || echo "None"
@@ -486,13 +514,6 @@ run() {
 
     log "Fallback AP service started"
     log "Script: $SCRIPT_PATH"
-
-    # Open the lock fd once for the life of the process. Using `flock`
-    # directly against this fd (instead of wrapping each tick in its own
-    # `( ... ) 9>"$LOCK_FILE"` subshell) matters: any variable a tick
-    # updates - like last_attempt below - has to survive into the next
-    # loop iteration, and a subshell would silently throw those updates
-    # away when it exits.
     exec 9>"$LOCK_FILE"
 
     flock 9

install.sh

@@ -11,10 +11,35 @@ if [ "$EUID" -ne 0 ]; then
     exit 1
 fi
 
-echo "Downloading..."
+prompt() {
+    local __var="$1" __question="$2" __default="$3" __answer=""
+    read -r -p "$__question [$__default]: " __answer < /dev/tty || __answer=""
+    printf -v "$__var" '%s' "${__answer:-$__default}"
+}
+
+EXISTING_CONFIG="/etc/fallback-ap.conf"
+
+if [ -f "$EXISTING_CONFIG" ]; then
+    # shellcheck disable=SC1090
+    source "$EXISTING_CONFIG"
+fi
+
+DEFAULT_SSID="${SAVED_SSID:-$(hostname)}"
+DEFAULT_PASSWORD="${SAVED_PASSWORD:-guesswhatitis}"
+DEFAULT_CIDR="${SAVED_CIDR:-10.10.10.1/24}"
+DEFAULT_DHCP_START_OCTET="${SAVED_DHCP_START_OCTET:-100}"
+DEFAULT_DHCP_END_OCTET="${SAVED_DHCP_END_OCTET:-250}"
+
+[ -z "${FALLBACK_AP_SSID:-}" ]              && prompt FALLBACK_AP_SSID "Access point SSID" "$DEFAULT_SSID"
+[ -z "${FALLBACK_AP_PASSWORD:-}" ]          && prompt FALLBACK_AP_PASSWORD "Access point passphrase" "$DEFAULT_PASSWORD"
+[ -z "${FALLBACK_AP_CIDR:-}" ]              && prompt FALLBACK_AP_CIDR "Access point subnet (CIDR)" "$DEFAULT_CIDR"
+[ -z "${FALLBACK_AP_DHCP_START_OCTET:-}" ]  && prompt FALLBACK_AP_DHCP_START_OCTET "DHCP range start (last octet)" "$DEFAULT_DHCP_START_OCTET"
+[ -z "${FALLBACK_AP_DHCP_END_OCTET:-}" ]    && prompt FALLBACK_AP_DHCP_END_OCTET "DHCP range end   (last octet)" "$DEFAULT_DHCP_END_OCTET"
+
+export FALLBACK_AP_SSID FALLBACK_AP_PASSWORD FALLBACK_AP_CIDR FALLBACK_AP_DHCP_START_OCTET FALLBACK_AP_DHCP_END_OCTET
+
+echo "Downloading fallback-ap..."
 curl -fsSL "$SCRIPT_URL" -o "$INSTALL_PATH"
-
 chmod +x "$INSTALL_PATH"
-
 echo "Running installer..."
 "$INSTALL_PATH" install