#!/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
};'
# Display the final results
awk_print_ifdata='
iflen=0;
for ( ifnam in ifdata ) { if(length(ifnam)>iflen) iflen=length(ifnam) };
for ( ifnam in ifdata ) { split(ifdata[ifnam], data, "^"); for (v in data) { if (length(data[v])>1) printf("%-" int(iflen+1) "s %s\n", ifnam, data[v]) }}
'

case "$UNAME" in
    Darwin|FreeBSD|AIX)
        test -n "$IFACE" && if_args="$IFACE"
        test -z "$if_args" && if_args="-a"
        ifconfig $if_args | $awk "$awk_mask2cdr"'
            /^[a-z0-9:]+/ { ifnam=$1 };

            # Ex: `inet x.x.x.x netmask 0xffffff00 broadcast x.x.x.x`
            $1 == "inet" { ifdata[ifnam]=ifdata[ifnam] "^" $2 "/" mask2cdr($4) };
            # Ex: `inet6 xx:xx::1 prefixlen 64 autoconf secured`
            $1 == "inet6" && !/scopeid|inet6 ::1|temporary/ { ifdata[ifnam]=ifdata[ifnam] "^" $2 "/" $4 };

            END { '"$awk_print_ifdata"'}'
        ;;
    Linux)
        test -n "$IFACE" && if_args="$IFACE"
        test -z "$if_args" && if_args="-a"
        ifconfig $if_args | $awk "$awk_mask2cdr"'
            /^[^ ]+/ { gsub(":", "", $1); ifnam=$1 ":" };

            # ifconfig net-tools 1.x
            # Ex: `inet addr:x.x.x.x  Bcast:x.x.x.x  Mask:255.255.255.0`
            $1 == "inet" && /inet addr/ { ifdata[ifnam]=ifdata[ifnam] "^" substr($2,6) "/" mask2cdr(substr($0,index($0,"Mask:")+5)) };
            # Ex: `inet6 addr: xx:xx::1/64 Scope:Global`
            $1 == "inet6" && /Scope:Global/ { ifdata[ifnam]=ifdata[ifnam] "^" $3 }

            # ifconfig net-tools 2.x
            # Ex: `inet x.x.x.x  netmask 255.255.255.0  broadcast x.x.x.x`
            $1 == "inet" && !/inet addr/ { ifdata[ifnam]=ifdata[ifnam] "^" $2 "/" mask2cdr($4) };
            # Ex: `inet6 xx:xx::1  prefixlen 64  scopeid 0x0<global>`
            $1 == "inet6" && /scopeid 0x0<global>/ { ifdata[ifnam]=ifdata[ifnam] "^" $2 "/" $4 }

            END { '"$awk_print_ifdata"'}'
        ;;
    SunOS)
        test -x "/usr/gnu/bin/awk" && awk=/usr/gnu/bin/awk
        test -n "$IFACE" && if_args="$IFACE"
        test -z "$if_args" && if_args="-a"
        ifconfig $if_args | $awk "$awk_mask2cdr"'
            /^[a-z0-9:]+/ { ifnam=$1 };

            $1 == "inet" { ifdata[ifnam]=ifdata[ifnam] "^" $2 "/" mask2cdr($4) };
            $1 == "inet6" && !/inet6 ::|inet6 fe80:/ { ifdata[ifnam]=ifdata[ifnam] "^" $2 }

            END { '"$awk_print_ifdata"'}'
        ;;
    *)
        echo "Unhandled host-type: $UNAME"
esac