refactoring: split helper functions into smaller scripts (#2420)

target/scripts/helpers/network.sh

@@ -0,0 +1,40 @@
+#! /bin/bash
+
+function _mask_ip_digit
+{
+  if [[ ${1} -ge 8 ]]
+  then
+    MASK=255
+  elif [[ ${1} -le 0 ]]
+  then
+    MASK=0
+  else
+    VALUES=(0 128 192 224 240 248 252 254 255)
+    MASK=${VALUES[${1}]}
+  fi
+
+  local DVAL=${2}
+  ((DVAL&=MASK))
+
+  echo "${DVAL}"
+}
+
+# Transforms a specific IP with CIDR suffix
+# like 1.2.3.4/16 to subnet with cidr suffix
+# like 1.2.0.0/16.
+# Assumes correct IP and subnet are provided.
+function _sanitize_ipv4_to_subnet_cidr
+{
+  local DIGIT_PREFIX_LENGTH="${1#*/}"
+
+  declare -a MASKED_DIGITS DIGITS
+  IFS='.' ; read -r -a DIGITS < <(echo "${1%%/*}") ; unset IFS
+
+  for ((i = 0 ; i < 4 ; i++))
+  do
+    MASKED_DIGITS[i]=$(_mask_ip_digit "${DIGIT_PREFIX_LENGTH}" "${DIGITS[i]}")
+    DIGIT_PREFIX_LENGTH=$((DIGIT_PREFIX_LENGTH - 8))
+  done
+
+  echo "${MASKED_DIGITS[0]}.${MASKED_DIGITS[1]}.${MASKED_DIGITS[2]}.${MASKED_DIGITS[3]}/${1#*/}"
+}