#!/bin/sh
# Usage: ipaddr [<iface>]
# Show the IP address (IPv4 and/or IPv6) for interface <iface> or all interfaces
# when no <iface> given.

UNAME=$(uname)
IFACE=$1
awk="command awk"

# Helper function for converting a hex (or decimal) netmask into CIDR format
awk_mask2cdr='
function mask2cdr(mask) {
    if(mask ~ /[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+/) {
        split(mask,d,".");
        mask = sprintf("0x%x%x%x%x",d[1],d[2],d[3],d[4]);
    };
    sub("^0x","",mask);
    cidr=0;
    while(mask != "") {
        digit=substr(mask,1,1);
        mask=substr(mask,2);
        if(digit ~ /f|F/) cidr += 4;
        if(digit ~ /e|E/) cidr += 3;
        if(digit ~ /c|C/) cidr += 2;
        if(digit ~ /8/) cidr += 1;
    };
    return cidr
};'

case "$UNAME" in
    Darwin|FreeBSD)
        test -n "$IFACE" && if_args="$IFACE"
        test -z "$if_args" && if_args="-a"
        ifconfig $if_args | $awk "$awk_mask2cdr"'
            /^[a-z-0-9]/ {iface=$1};
            $1 == "inet" {printf("%-10s %s/%s\n",iface,$2,mask2cdr($4))};
            $1 == "inet6" && !/scopeid|inet6 ::1|temporary/ {printf("%-10s %s/%s\n",iface,$2,$4)}'
        ;;
    Linux)
        test -n "$IFACE" && if_args="$IFACE"
        test -z "$if_args" && if_args="-a"
        ifconfig $if_args | $awk "$awk_mask2cdr"'
            /^[^ ]+/ {iface=$1};
            $1 == "inet" { printf("%-10s %s/%s\n", iface ":", substr($2,6), mask2cdr(substr($0,index($0,"Mask:")+5))) };
            $1 == "inet6" && /Scope:Global/ { printf("%-10s %s\n", iface ":", $3) }'
        ;;
    SunOS)
        test -x "/usr/gnu/bin/awk" && awk=/usr/gnu/bin/awk
        test -n "$IFACE" && if_args="$IFACE"
        test -z "$if_args" && if_args="-a"
        ifconfig $if_args | $awk "$awk_mask2cdr"'
            /^[a-z0-9]+/ {iface=$1};
            $1 == "inet" { printf("%-10s %s/%s\n", iface, $2, mask2cdr($4)) };
            $1 == "inet6" && !/inet6 ::|inet6 fe80:/ { printf("%-10s %s\n", iface, $2) }'
        ;;
    *)
        echo "Unhandled host-type: $UNAME"
esac