initscripts: Add some basic functions for IP address maths

Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>

diff --git a/src/initscripts/networking/functions.network b/src/initscripts/networking/functions.network
index 4463b75879fe97102527f7d3fa0da40da2e109ad..e134d0cce40d21a81e7bd402953a6962dbe8bd78 100644 (file)
--- a/src/initscripts/networking/functions.network
+++ b/src/initscripts/networking/functions.network
@@ -22,6 +22,150 @@
 eval $(/usr/local/bin/readhash /var/ipfire/ethernet/settings)
 eval $(/usr/local/bin/readhash /var/ipfire/dns/settings)
 
+ip2bin() {
+       local address="${1}"
+
+       local IFS='.'
+       local octet
+
+       local n=0
+
+       for octet in ${address}; do
+               # Shift n
+               (( n <<= 8 ))
+
+               # Apply the octet
+               (( n |= octet ))
+       done
+
+       echo "${n}"
+}
+
+bin2ip() {
+       local n="${1}"
+
+       local IFS='.'
+       local address=()
+
+       for i in {3..0}; do
+               address+=( $(( n >> (8 * i) & 0xff )) )
+       done
+
+       echo "${address[*]}"
+}
+
+network_get_address() {
+       local network="${1}"
+
+       # Return everything before the slash
+       echo "${network%%/*}"
+}
+
+network_get_prefix() {
+       local network="${1}"
+
+       # Consider everything after the / the prefix
+       local prefix="${network##*/}"
+
+       # If the prefix is valid, return it
+       if network_prefix_is_valid "${prefix}"; then
+               echo "${prefix}"
+
+       # Otherwise it might be a subnet mask
+       else
+               network_netmask_to_prefix "${prefix}"
+       fi
+}
+
+network_get_netmask() {
+       local network="${1}"
+
+       # Consider everything after the / the netmask
+       local netmask="${network##*/}"
+
+       # If we have a prefix, we need to convert
+       if network_prefix_is_valid "${netmask}"; then
+               network_prefix_to_netmask "${netmask}"
+
+       # Otherwise return what we got
+       else
+               echo "${netmask}"
+       fi
+}
+
+network_prefix_is_valid() {
+       local prefix="${1}"
+
+       # The prefix must be numbers only
+       if ! [[ "${prefix}" =~ ^[0-9]+$ ]]; then
+               return 1
+       fi
+
+       # Must be a number between 0 and 32 (inclusive)
+       [ "${prefix}" -ge 0 -a "${prefix}" -le 32 ]
+}
+
+network_prefix_to_netmask() {
+       local prefix="${1}"
+
+       # Set n with all bits set
+       local n=0xffffffff
+
+       # Shift
+       (( n <<= (32 - prefix) ))
+
+       # Convert back
+       bin2ip "${n}"
+}
+
+network_netmask_to_prefix() {
+       local netmask="${1}"
+
+       local prefix=0
+
+       # Convert to binary
+       local n="$(ip2bin "${netmask}")"
+
+       while [ "${n}" -gt 0 ]; do
+               # If the highest bit is not set, we are done
+               [ "$(( n & (1 << 31) ))" -eq 0 ] && break
+
+               # Increment prefix & shift n
+               (( prefix++ ))
+               (( n <<= 1 ))
+       done
+
+       echo "${prefix}"
+}
+
+network_address_in_network() {
+       local address="${1}"
+       local network="${2}"
+
+       # Split the network into its address & mask
+       local netaddr="$(network_get_address "${network}")"
+       local netmask="$(network_get_netmask "${network}")"
+
+       # Abort if we could not parse the network
+       if [ -z "${netaddr}" -o -z "${netmask}" ]; then
+               return 1
+       fi
+
+       # Convert everything to binary
+       address="$(ip2bin "${address}")"
+       netaddr="$(ip2bin "${netaddr}")"
+       netmask="$(ip2bin "${netmask}")"
+
+       # Ensure the network address is the first address
+       (( netaddr &= netmask ))
+
+       # Compute broadcast
+       local broadcast=$(( netaddr | (~netmask & 0xffffffff) ))
+
+       # Return true if address is in the network
+       [ "${address}" -ge "${netaddr}" -a "${address}" -le "${broadcast}" ]
+}
+
 dhcpcd_get_pid() {
                # This function returns the pid of a dhcpcd by a given
                # network device, if a pidfile exists.