Update install.sh

install.sh

@@ -11,12 +11,57 @@ if [ "$EUID" -ne 0 ]; then
     exit 1
 fi
 
+# Ask a question; Enter accepts the default.
 prompt() {
     local __var="$1" __question="$2" __default="$3" __answer=""
     read -r -p "$__question [$__default]: " __answer < /dev/tty || __answer=""
     printf -v "$__var" '%s' "${__answer:-$__default}"
 }
 
+# Like prompt, but "blank" is a legitimate value. Enter accepts the default;
+# typing the clear word (e.g. "all" or "none") sets the value to empty.
+prompt_blankable() {
+    local __var="$1" __question="$2" __default="$3" __clear="$4" __answer=""
+    read -r -p "$__question [${__default:-$__clear}]: " __answer < /dev/tty || __answer=""
+
+    case "$__answer" in
+        "")          __answer="$__default" ;;
+        "$__clear")  __answer="" ;;
+    esac
+
+    printf -v "$__var" '%s' "${__answer// /}"
+}
+
+# Ask until the answer is one of the allowed choices. Enter accepts the default.
+prompt_choice() {
+    local __var="$1" __question="$2" __default="$3" __answer="" __opt
+    shift 3
+
+    while true; do
+        read -r -p "$__question [$__default]: " __answer < /dev/tty || __answer=""
+        __answer="${__answer:-$__default}"
+
+        for __opt in "$@"; do
+            if [ "$__answer" = "$__opt" ]; then
+                printf -v "$__var" '%s' "$__answer"
+                return 0
+            fi
+        done
+
+        echo "  Please enter one of: $*"
+    done
+}
+
+# Lists wireless interfaces (those with a /sys/class/net/<iface>/wireless dir).
+detect_wireless() {
+    local dir
+    for dir in /sys/class/net/*; do
+        if [ -d "$dir/wireless" ]; then
+            basename "$dir"
+        fi
+    done
+}
+
 EXISTING_CONFIG="/etc/fallback-ap.conf"
 
 if [ -f "$EXISTING_CONFIG" ]; then
@@ -24,20 +69,79 @@ if [ -f "$EXISTING_CONFIG" ]; then
     source "$EXISTING_CONFIG"
 fi
 
+DETECTED_WIFI="$(detect_wireless | tr '\n' ' ')"
+DETECTED_WIFI="${DETECTED_WIFI% }"
+
 DEFAULT_SSID="${SAVED_SSID:-$(hostname)}"
 DEFAULT_PASSWORD="${SAVED_PASSWORD:-abcd1234}"
+DEFAULT_IFACE="${SAVED_IFACE:-${DETECTED_WIFI%% *}}"
+DEFAULT_IFACE="${DEFAULT_IFACE:-wlan0}"
 DEFAULT_CIDR="${SAVED_CIDR:-10.10.10.1/24}"
 DEFAULT_DHCP_START_OCTET="${SAVED_DHCP_START_OCTET:-100}"
 DEFAULT_DHCP_END_OCTET="${SAVED_DHCP_END_OCTET:-250}"
+DEFAULT_MONITOR_IFACE="${SAVED_MONITOR_IFACE-}"
+DEFAULT_IGNORE_IFACE="${SAVED_IGNORE_IFACE-}"
+DEFAULT_CHECK_MODE="${SAVED_CHECK_MODE:-link}"
+DEFAULT_CHECK_TARGETS="${SAVED_CHECK_TARGETS:-1.1.1.1 8.8.8.8}"
+
+# --- Access point ----------------------------------------------------------------------------------------------------
 
 [ -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"
+
+if [ -z "${FALLBACK_AP_IFACE:-}" ]; then
+    if [ -n "$DETECTED_WIFI" ]; then
+        echo "Detected Wi-Fi interfaces: $DETECTED_WIFI"
+    fi
+    prompt FALLBACK_AP_IFACE "Interface to create the access point on" "$DEFAULT_IFACE"
+fi
+
 [ -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
+# --- Connectivity monitoring -----------------------------------------------------------------------------------------
+#
+# The AP only starts when none of the monitored interfaces are online, and it
+# is only ever created on the interface chosen above.
+#
+# These use "unset" (not "empty") to decide whether to ask, because an empty
+# FALLBACK_AP_MONITOR_IFACE / FALLBACK_AP_IGNORE_IFACE is a valid answer
+# meaning "all real interfaces" / "ignore nothing".
 
+if [ -z "${FALLBACK_AP_MONITOR_IFACE+x}" ]; then
+    echo
+    echo "Which interfaces should count as 'online'? Enter a comma-separated list"
+    echo "(e.g. eth0,wlan0), or 'all' for every real interface. Virtual interfaces"
+    echo "(docker, veth, bridges, VPNs) are skipped automatically."
+    prompt_blankable FALLBACK_AP_MONITOR_IFACE "Interfaces to monitor" "$DEFAULT_MONITOR_IFACE" "all"
+fi
+
+if [ -z "$FALLBACK_AP_MONITOR_IFACE" ] && [ -z "${FALLBACK_AP_IGNORE_IFACE+x}" ]; then
+    echo
+    echo "Any physical interfaces to ignore (globs allowed, e.g. enx*,usb0)?"
+    prompt_blankable FALLBACK_AP_IGNORE_IFACE "Interfaces to ignore" "$DEFAULT_IGNORE_IFACE" "none"
+fi
+
+if [ -z "${FALLBACK_AP_CHECK_MODE:-}" ]; then
+    echo
+    echo "How should 'online' be determined?"
+    echo "  link     - the interface is connected (an upstream outage keeps the AP off)"
+    echo "  internet - the interface is connected AND can ping out"
+    prompt_choice FALLBACK_AP_CHECK_MODE "Check mode" "$DEFAULT_CHECK_MODE" link internet
+fi
+
+if [ "$FALLBACK_AP_CHECK_MODE" = "internet" ] && [ -z "${FALLBACK_AP_CHECK_TARGETS:-}" ]; then
+    prompt FALLBACK_AP_CHECK_TARGETS "Hosts to ping (space-separated)" "$DEFAULT_CHECK_TARGETS"
+fi
+
+export FALLBACK_AP_SSID FALLBACK_AP_PASSWORD FALLBACK_AP_IFACE FALLBACK_AP_CIDR FALLBACK_AP_DHCP_START_OCTET FALLBACK_AP_DHCP_END_OCTET
+export FALLBACK_AP_CHECK_MODE
+[ -n "${FALLBACK_AP_MONITOR_IFACE+x}" ] && export FALLBACK_AP_MONITOR_IFACE
+[ -n "${FALLBACK_AP_IGNORE_IFACE+x}" ]  && export FALLBACK_AP_IGNORE_IFACE
+[ -n "${FALLBACK_AP_CHECK_TARGETS+x}" ] && export FALLBACK_AP_CHECK_TARGETS
+
+echo
 echo "Downloading fallback-ap..."
 curl -fsSL "$SCRIPT_URL" -o "$INSTALL_PATH"
 chmod +x "$INSTALL_PATH"