#!/usr/bin/env etsh
:
: etsh - " Force sh(1), csh(1), and other shells to exit w/ error! " <'' ;;;
:
: "  @(#)$Id: 64df03aee04c5315bbc6d1843102526a8d0329e2 $  "
:
: "  The author of this file, J.A. Neitzel <jan (at) etsh (dot) io>,  "
: "  hereby grants it to the public domain.                           "
:

:
: "  Get client/user IPv6 and/or IPv4 address(es).         "
:
: "  This command is useful because ifconfig(8) may not    "
: "  reflect whether or not addresses are public.          "
:
: "  Exit w/ zero status (true) if request(s) succeed(s).  "
: "  Otherwise, exit w/ non-zero status (false).           "
:
: "  usage: myip [-4 | -46 | -6]  "
:

: " Check for correct usage. "
: >>$0'' <'' ; : >>$1'' <'' ; killer $0 myip
if ! \( $# -eq 0 -o \( \
	$# -eq 1 -a \( X$1 = X-4 -o X$1 = X-46 -o X$1 = X-6 \) \
     \) \) if { exit } pusage $0 '"[-4 | -46 | -6]"'

: " Exit w/ error if which is not found, fails, or curl is not found. "
trap : 2 3
if ! { fd2 which which >/dev/null } if { exit } perror $0 '"which: Not found"'
if   { fd2 which . >/dev/null } if { exit } perror $0 '"which: Invalid results"'
if ! { fd2 which curl >/dev/null } if { exit } perror $0 '"curl: Not found"'
trap - 2 3

: " Set variables used below. "
set C 'curl --fail --silent --show-error'
set D 'https://myip6.v6shell.org/'
set E 'https://myip.v6shell.org/'
set F 'https://myip4.v6shell.org/'
: " Default to zero status (true). "
set G 0 ; set H 0 ; set I 0

: " Do the work now. "
if $# -eq 1 -a X$1 = X-4 goto IPv4
if $# -eq 1 -a X$1 = X-46 goto IPv6orIPv4
: IPv6
	echo 'IPv6:'
	$C $D >/dev/null
	set G $?
	if $G -ne 0 if { echo '	Cannot connect via IPv6.' } goto Jump
		fd2 -f/dev/null -- $C $D | sed 's/^/	/'
		: fallthrough
	: Jump
		if $# -ne 0 exit ; if $G -eq 0
		echo
		: fallthrough

: IPv6orIPv4
	echo 'IPv6 <-> IPv4:'
	$C $E >/dev/null
	set H $?
	if $H -ne 0 if { echo '	Cannot connect via IPv6 or IPv4.' } goto Jump1
		fd2 -f/dev/null -- $C $E | sed 's/^/	/'
		: fallthrough
	: Jump1
		if $# -ne 0 exit ; if $H -eq 0
		echo
		: fallthrough

: IPv4
	echo 'IPv4:'
	$C $F >/dev/null
	set I $?
	if $I -ne 0 if { echo '	Cannot connect via IPv4.' } goto Done
		fd2 -f/dev/null -- $C $F | sed 's/^/	/'
		: fallthrough

: Done
	if $G -ne 0 -o $H -ne 0 -o $I -ne 0 if { exit } false
	: zero status