expand ipv6 address in shell script

问题:

I'd like to update a djbdns (dbndns) configuration file based on a given IPv6 address, e.g. 2a01:488:66:1000:523:f116:0:1 or ::1.

dbndns requires expanded IPv6 addresses, e.g. 2a010488006610000523f11600000001 for 2a01:488:66:1000:523:f116:0:1.

What's the most simple way to expand such an IPv6 address?

回答1:

Using sipcalc might do it. It gives more information than you need, but a bit of grep and cut can solve that :-)

$ EXPANDED=`sipcalc 2001::1 | fgrep Expanded | cut -d '-' -f 2`
$ echo $EXPAND
2001:0000:0000:0000:0000:0000:0000:0001

For reference, this is the full output of sipcalc:

$ sipcalc 2001::1
-[ipv6 : 2001::1] - 0

[IPV6 INFO]
Expanded Address        - 2001:0000:0000:0000:0000:0000:0000:0001
Compressed address      - 2001::1
Subnet prefix (masked)  - 2001:0:0:0:0:0:0:1/128
Address ID (masked)     - 0:0:0:0:0:0:0:0/128
Prefix address          - ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff
Prefix length           - 128
Address type            - Aggregatable Global Unicast Addresses
Network range           - 2001:0000:0000:0000:0000:0000:0000:0001 -
                          2001:0000:0000:0000:0000:0000:0000:0001

回答2:

I recently wanted a no-dependency solution that would be portable across shells and work on platforms such as openwrt. I came up with the following snippet:

# helper to convert hex to dec (portable version)
hex2dec(){
    [ "$1" != "" ] && printf "%d" "$(( 0x$1 ))"
}

# expand an ipv6 address
expand_ipv6() {
    ip=$1

    # prepend 0 if we start with :
    echo $ip | grep -qs "^:" && ip="0${ip}"

    # expand ::
    if echo $ip | grep -qs "::"; then
        colons=$(echo $ip | sed 's/[^:]//g')
        missing=$(echo ":::::::::" | sed "s/$colons//")
        expanded=$(echo $missing | sed 's/:/:0/g')
        ip=$(echo $ip | sed "s/::/$expanded/")
    fi

    blocks=$(echo $ip | grep -o "[0-9a-f]\+")
    set $blocks

    printf "%04x:%04x:%04x:%04x:%04x:%04x:%04x:%04x\n" \
        $(hex2dec $1) \
        $(hex2dec $2) \
        $(hex2dec $3) \
        $(hex2dec $4) \
        $(hex2dec $5) \
        $(hex2dec $6) \
        $(hex2dec $7) \
        $(hex2dec $8)
}

I also have this function to compress

# returns a compressed ipv6 address under the form recommended by RFC5952
compress_ipv6() {
    ip=$1

    blocks=$(echo $ip | grep -o "[0-9a-f]\+")
    set $blocks

    # compress leading zeros
    ip=$(printf "%x:%x:%x:%x:%x:%x:%x:%x\n" \
        $(hex2dec $1) \
        $(hex2dec $2) \
        $(hex2dec $3) \
        $(hex2dec $4) \
        $(hex2dec $5) \
        $(hex2dec $6) \
        $(hex2dec $7) \
        $(hex2dec $8)
    )

    # prepend : for easier matching
    ip=:$ip

    # :: must compress the longest chain
    for pattern in :0:0:0:0:0:0:0:0 \
            :0:0:0:0:0:0:0 \
            :0:0:0:0:0:0 \
            :0:0:0:0:0 \
            :0:0:0:0 \
            :0:0; do
        if echo $ip | grep -qs $pattern; then
            ip=$(echo $ip | sed "s/$pattern/::/")
            # if the substitution occured before the end, we have :::
            ip=$(echo $ip | sed 's/:::/::/')
            break # only one substitution
        fi
    done

    # remove prepending : if necessary
    echo $ip | grep -qs "^:[^:]" && ip=$(echo $ip | sed 's/://')

    echo $ip
}

You can combine them to test if a given input is an ipv6

# a valid ipv6 is either the expanded form or the compressed one
is_ipv6(){
    expanded="$(expand_ipv6 $1)"
    [ "$1" = "$expanded" ] && return 0
    compressed="$(compress_ipv6 $expanded)"
    [ "$1" = "$compressed" ] && return 0
    return 1
}

I hope this helps! Those snippets are taken from https://github.com/chmduquesne/wg-ip. If you spot any bug, please contribute!

回答3:

is this ok for you?

kent$  echo "2a01:488:66:1000:523:f116:0:1"|awk -F: '{for(i=1;i<=NF;i++)x=x""sprintf ("%4s", $i);gsub(/ /,"0",x);print x}'
2a010488006610000523f11600000001