Add API functions

Signed-off-by: Christian König <ckoenig@posteo.de>

advanced/Scripts/api.sh

@@ -0,0 +1,140 @@
+#!/usr/bin/env sh
+# shellcheck disable=SC3043 #https://github.com/koalaman/shellcheck/wiki/SC3043#exceptions
+
+# Pi-hole: A black hole for Internet advertisements
+# (c) 2017 Pi-hole, LLC (https://pi-hole.net)
+# Network-wide ad blocking via your own hardware.
+#
+# Script to hold api functions for use in other scripts
+#
+# This file is copyright under the latest version of the EUPL.
+# Please see LICENSE file for your rights under this license.
+
+
+# The basic usage steps are
+# 1) Test Availability of the API
+# 2) Try to authenticate (read password if needed)
+# 3) Get the data from the API endpoint
+# 4) Delete the session
+
+
+TestAPIAvailability() {
+
+    # as we are running locally, we can get the port value from FTL directly
+    PORT="$(pihole-FTL --config webserver.port)"
+    PORT="${PORT%%,*}"
+
+    availabilityResonse=$(curl -s -o /dev/null -w "%{http_code}" "http://localhost:${PORT}/api/auth")
+
+    # test if http status code was 200 (OK) or 401 (authentication required)
+    if [ ! "${availabilityResonse}" = 200 ] && [ ! "${availabilityResonse}" = 401 ]; then
+        echo "API not available at: http://localhost:${PORT}/api"
+        echo "Exiting."
+        exit 1
+    fi
+}
+
+Authenthication() {
+    # Try to authenticate
+    LoginAPI
+
+    while [ "${validSession}" = false ] || [ -z "${validSession}" ] ; do
+        echo "Authentication failed. Please enter your Pi-hole password"
+
+        # secretly read the password
+        secretRead; printf '\n'
+
+        # Try to authenticate again
+        LoginAPI
+    done
+
+    # Loop exited, authentication was successful
+    echo "Authentication successful."
+
+}
+
+LoginAPI() {
+	sessionResponse="$(curl --silent -X POST "http://localhost:${PORT}/api/auth" --user-agent "Pi-hole cli " --data "{\"password\":\"${password}\"}" )"
+
+  if [ -z "${sessionResponse}" ]; then
+    echo "No response from FTL server. Please check connectivity"
+    exit 1
+  fi
+	# obtain validity and session ID from session response
+	validSession=$(echo "${sessionResponse}"| jq .session.valid 2>/dev/null)
+	SID=$(echo "${sessionResponse}"| jq --raw-output .session.sid 2>/dev/null)
+}
+
+DeleteSession() {
+    # if a valid Session exists (no password required or successful authenthication) and
+    # SID is not null (successful authenthication only), delete the session
+    if [ "${validSession}" = true ] && [ ! "${SID}" = null ]; then
+        # Try to delete the session. Omit the output, but get the http status code
+        deleteResponse=$(curl -s -o /dev/null -w "%{http_code}" -X DELETE "http://localhost:${PORT}/api/auth"  -H "Accept: application/json" -H "sid: ${SID}")
+
+        case "${deleteResponse}" in
+            "200") printf "%b" "A session that was not created cannot be deleted (e.g., empty API password).\n";;
+            "401") printf "%b" "Logout attempt without a valid session. Unauthorized!\n";;
+            "410") printf "%b" "Session successfully deleted.\n";;
+         esac;
+    fi
+
+}
+
+GetFTLData() {
+  local data
+  # get the data from querying the API as well as the http status code
+  data=$(curl -s -X GET "http://localhost:${PORT}/api$1" -H "Accept: application/json" -H "sid: ${SID}" )
+  echo "${data}"
+}
+
+secretRead() {
+
+    # POSIX compliant function to read user-input and
+    # mask every character entered by (*)
+    #
+    # This is challenging, because in POSIX, `read` does not support
+    # `-s` option (suppressing the input) or
+    # `-n` option (reading n chars)
+
+
+    # This workaround changes the terminal characteristics to not echo input and later resets this option
+    # credits https://stackoverflow.com/a/4316765
+    # showing asterisk instead of password
+    # https://stackoverflow.com/a/24600839
+    # https://unix.stackexchange.com/a/464963
+
+
+    # Save current terminal settings (needed for later restore after password prompt)
+    stty_orig=$(stty -g)
+
+    stty -echo # do not echo user input
+    stty -icanon min 1 time 0 # disable canonical mode https://man7.org/linux/man-pages/man3/termios.3.html
+
+    unset password
+    unset key
+    unset charcount
+    charcount=0
+    while key=$(dd ibs=1 count=1 2>/dev/null); do #read one byte of input
+        if [ "${key}" = "$(printf '\0' | tr -d '\0')" ] ; then
+            # Enter - accept password
+            break
+        fi
+        if [ "${key}" = "$(printf '\177')" ] ; then
+            # Backspace
+            if [ $charcount -gt 0 ] ; then
+                charcount=$((charcount-1))
+                printf '\b \b'
+                password="${password%?}"
+            fi
+        else
+            # any other character
+            charcount=$((charcount+1))
+            printf '*'
+            password="$password$key"
+        fi
+    done
+
+    # restore original terminal settings
+    stty "${stty_orig}"
+}