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base-files: ipcalc.sh: Add netmask2prefix function

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Also add is_contiguous to check if it's a valid netmask.

Signed-off-by: Philip Prindeville <philipp@redfish-solutions.com>
This commit is contained in:
Philip Prindeville 2023-11-11 12:37:20 -07:00
parent 6cdc429a48
commit dd256099c3
2 changed files with 41 additions and 5 deletions
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7
package/base-files/files/bin/ipcalc.sh
View File

@ -44,6 +44,7 @@ case "$1" in
# data is n.n.n.n/m.m.m.m format, like on a Cisco router # data is n.n.n.n/m.m.m.m format, like on a Cisco router
str2ip ipaddr "${1%/*}" || exit 1 str2ip ipaddr "${1%/*}" || exit 1
str2ip netmask "${1#*/}" || exit 1 str2ip netmask "${1#*/}" || exit 1
netmask2prefix prefix "$netmask" || exit 1
shift shift
;; ;;
*/*) */*)
@ -62,6 +63,7 @@ case "$1" in
# address and netmask as two separate arguments # address and netmask as two separate arguments
str2ip ipaddr "$1" || exit 1 str2ip ipaddr "$1" || exit 1
str2ip netmask "$2" || exit 1 str2ip netmask "$2" || exit 1
netmask2prefix prefix "$netmask" || exit 1
shift 2 shift 2
;; ;;
esac esac
@ -71,11 +73,6 @@ if [ $# -ne 0 ] && [ $# -ne 2 ]; then
usage usage
fi fi
if ! bitcount prefix "$netmask"; then
printf "Invalid netmask (%s)\n" "$netmask" >&2
exit 1
fi
# complement of the netmask, i.e. the hostmask # complement of the netmask, i.e. the hostmask
hostmask=$((netmask ^ 0xffffffff)) hostmask=$((netmask ^ 0xffffffff))
network=$((ipaddr & netmask)) network=$((ipaddr & netmask))

39
package/base-files/files/lib/functions/ipv4.sh
View File

@ -157,3 +157,42 @@ prefix2netmask() {
export -- "$__var=$(((~(uint_max >> __n)) & uint_max))" export -- "$__var=$(((~(uint_max >> __n)) & uint_max))"
} }
_is_contiguous() {
local __x="$1" # no checking done
local __y=$((~__x & uint_max))
local __z=$(((__y + 1) & uint_max))
[ $((__z & __y)) -eq 0 ]
}
# check argument as being contiguous upper bits (and yes,
# 0 doesn't have any discontiguous bits).
is_contiguous() {
local __var="$1" __x="$2" __val=0
assert_uint32 "$__x" || return 1
local __y=$((~__x & uint_max))
local __z=$(((__y + 1) & uint_max))
[ $((__z & __y)) -eq 0 ] && __val=1
export -- "$__var=$__val"
}
# convert mask to prefix, validating that it's a conventional
# (contiguous) netmask.
netmask2prefix() {
local __var="$1" __n="$2" __cont __bits
assert_uint32 "$__n" || return 1
is_contiguous __cont "$__n" || return 1
if [ $__cont -eq 0 ]; then
printf "Not a contiguous netmask (%08x)\n" "$__n" >&2
return 1
fi
bitcount __bits "$__n" # already checked
export -- "$__var=$__bits"
}