planktoscope/scripts/raspbian_configuration/usr/bin/autohotspotN

#!/bin/bash
#version 0.961-N/HS-I-PlanktonPlanet

#changes by PlanktonPlanet includes the following:
#- formatting and shellcheck validation
#- removal of ip forwarding setup

#You may share this script on the condition a reference to RaspberryConnect.com
#must be included in copies or derivatives of this script.

#Network Wifi & Hotspot with Internet
#A script to switch between a wifi network and an Internet routed Hotspot
#A Raspberry Pi with a network port required for Internet in hotspot mode.
#Works at startup or with a seperate timer or manually without a reboot
#Other setup required find out more at
#http://www.raspberryconnect.com

wifidev="wlan0" #device name to use. Default is wlan0.
ethdev="eth0"   #Ethernet port to use with IP tables
#use the command: iw dev ,to see wifi interface name

#These two lines capture the wifi networks the RPi is setup to use
wpassid=$(awk '/ssid="/{ print $0 }' /etc/wpa_supplicant/wpa_supplicant.conf | awk -F'ssid=' '{ print $2 }' | sed 's/\r//g' | awk 'BEGIN{ORS=","} {print}' | sed 's/\"/''/g' | sed 's/,$//')
IFS="," read -r -a ssids <<<"$wpassid"

#Note:If you only want to check for certain SSIDs
#Remove the # in in front of ssids=('mySSID1'.... below and put a # infront of all four lines above
# separated by a space, eg ('mySSID1' 'mySSID2')
#ssids=('mySSID1' 'mySSID2' 'mySSID3')

#Enter the Routers Mac Addresses for hidden SSIDs, seperated by spaces ie
#( '11:22:33:44:55:66' 'aa:bb:cc:dd:ee:ff' )
mac=()

ssidsmac=("${ssids[@]}" "${mac[@]}") #combines ssid and MAC for checking

createAdHocNetwork() {
       echo "Creating Hotspot"
       ip link set dev "$wifidev" down
       ip a add 192.168.4.1/24 brd + dev "$wifidev"
       ip link set dev "$wifidev" up
       dhcpcd -k "$wifidev" >/dev/null 2>&1
       systemctl start dnsmasq
       systemctl start hostapd
}

KillHotspot() {
       echo "Shutting Down Hotspot"
       ip link set dev "$wifidev" down
       systemctl stop hostapd
       systemctl stop dnsmasq
       ip addr flush dev "$wifidev"
       ip link set dev "$wifidev" up
       dhcpcd -n "$wifidev" >/dev/null 2>&1
}

ChkWifiUp() {
       echo "Checking WiFi connection ok"
       sleep 20                                                                    #give time for connection to be completed to router
       if ! wpa_cli -i "$wifidev" status | grep 'ip_address' >/dev/null 2>&1; then #Failed to connect to wifi (check your wifi settings, password etc)
              echo 'Wifi failed to connect, falling back to Hotspot.'
              wpa_cli terminate "$wifidev" >/dev/null 2>&1
              createAdHocNetwork
       fi
}

chksys() {
       #After some system updates hostapd gets masked using Raspbian Buster, and above. This checks and fixes
       #the issue and also checks dnsmasq is ok so the hotspot can be generated.
       #Check Hostapd is unmasked and disabled
       if systemctl -all list-unit-files hostapd.service | grep "hostapd.service masked" >/dev/null 2>&1; then
              systemctl unmask hostapd.service >/dev/null 2>&1
       fi
       if systemctl -all list-unit-files hostapd.service | grep "hostapd.service enabled" >/dev/null 2>&1; then
              systemctl disable hostapd.service >/dev/null 2>&1
              systemctl stop hostapd >/dev/null 2>&1
       fi
       #Check dnsmasq is disabled
       if systemctl -all list-unit-files dnsmasq.service | grep "dnsmasq.service masked" >/dev/null 2>&1; then
              systemctl unmask dnsmasq >/dev/null 2>&1
       fi
       if systemctl -all list-unit-files dnsmasq.service | grep "dnsmasq.service enabled" >/dev/null 2>&1; then
              systemctl disable dnsmasq >/dev/null 2>&1
              systemctl stop dnsmasq >/dev/null 2>&1
       fi
}

FindSSID() {
       #Check to see what SSID's and MAC addresses are in range
       ssidChk='NoSSid'
       i=0
       j=0
       until [ $i -eq 1 ]; do #wait for wifi if busy, usb wifi is slower.
              ssidreply=$( (iw dev "$wifidev" scan ap-force | grep -E "^BSS|SSID:") 2>&1) >/dev/null 2>&1
              #echo "SSid's in range: " $ssidreply
              printf '%s\n' "${ssidreply[@]}"
              echo "Device Available Check try " $j
              if ((j >= 5)); then #if busy 5 times goto hotspot
                     echo "Device busy or unavailable 5 times, going to Hotspot"
                     ssidreply=""
                     i=1
              elif echo "$ssidreply" | grep "No such device (-19)" >/dev/null 2>&1; then
                     echo "No Device Reported, try " $j
                     NoDevice
              elif echo "$ssidreply" | grep "Network is down (-100)" >/dev/null 2>&1; then
                     echo "Network Not available, trying again" $j
                     j=$((j + 1))
                     sleep 2
              elif echo "$ssidreply" | grep "Read-only file system (-30)" >/dev/null 2>&1; then
                     echo "Temporary Read only file system, trying again"
                     j=$((j + 1))
                     sleep 2
              elif echo "$ssidreply" | grep "Invalid exchange (-52)" >/dev/null 2>&1; then
                     echo "Temporary unavailable, trying again"
                     j=$((j + 1))
                     sleep 2
              elif echo "$ssidreply" | grep -v "resource busy (-16)" >/dev/null 2>&1; then
                     echo "Device Available, checking SSid Results"
                     i=1
              else #see if device not busy in 2 seconds
                     echo "Device unavailable checking again, try " $j
                     j=$((j + 1))
                     sleep 2
              fi
       done

       for ssid in "${ssidsmac[@]}"; do
              if (echo "$ssidreply" | grep -F -- "$ssid") >/dev/null 2>&1; then
                     #Valid SSid found, passing to script
                     echo "Valid SSID Detected, assesing Wifi status"
                     ssidChk=$ssid
                     return 0
              else
                     #No Network found, NoSSid issued"
                     echo "No SSid found, assessing WiFi status"
                     ssidChk='NoSSid'
              fi
       done
}

NoDevice() {
       #if no wifi device,ie usb wifi removed, activate wifi so when it is
       #reconnected wifi to a router will be available
       echo "No wifi device connected"
       wpa_supplicant -B -i "$wifidev" -c /etc/wpa_supplicant/wpa_supplicant.conf >/dev/null 2>&1
       exit 1
}

chksys
FindSSID

#Create Hotspot or connect to valid wifi networks
if [ "$ssidChk" != "NoSSid" ]; then
       if systemctl status hostapd | grep "(running)" >/dev/null 2>&1; then #hotspot running and ssid in range
              KillHotspot
              echo "Hotspot Deactivated, Bringing Wifi Up"
              wpa_supplicant -B -i "$wifidev" -c /etc/wpa_supplicant/wpa_supplicant.conf >/dev/null 2>&1
              ChkWifiUp
       elif { wpa_cli -i "$wifidev" status | grep 'ip_address'; } >/dev/null 2>&1; then #Already connected
              echo "Wifi already connected to a network"
       else #ssid exists and no hotspot running connect to wifi network
              echo "Connecting to the WiFi Network"
              wpa_supplicant -B -i "$wifidev" -c /etc/wpa_supplicant/wpa_supplicant.conf >/dev/null 2>&1
              ChkWifiUp
       fi
else #ssid or MAC address not in range
       if systemctl status hostapd | grep "(running)" >/dev/null 2>&1; then
              echo "Hostspot already active"
       elif { wpa_cli status | grep "$wifidev"; } >/dev/null 2>&1; then
              echo "Cleaning wifi files and Activating Hotspot"
              wpa_cli terminate >/dev/null 2>&1
              ip addr flush "$wifidev"
              ip link set dev "$wifidev" down
              # ip addr flush "$ethdev"
              # ip link set dev "$ethdev" down
              rm -r /var/run/wpa_supplicant >/dev/null 2>&1
              createAdHocNetwork
       else #"No SSID, activating Hotspot"
              createAdHocNetwork
       fi
fi