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Merged
legionus merged 1 commit into from
Aug 24, 2025
Merged

ip-address: Add ipv6_ip_matches #6

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22 changes: 20 additions & 2 deletions docs/shell-ip-address.md
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Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,7 @@ shell-ip-address(3)

# NAME

ipv4_ip_subnet, ipv4_mask2prefix, ipv4_prefix2mask, ipv4_ptonx, ipv6_addr_type, ipv6_ptonx, valid_ipv4 - functions to manipulate IP addresses
ipv4_ip_subnet, ipv4_mask2prefix, ipv4_prefix2mask, ipv4_ptonx, ipv6_addr_type, ipv6_ip_matches, ipv6_ptonx, valid_ipv4 - functions to manipulate IP addresses

# SYNOPSIS

Expand All @@ -13,12 +13,13 @@ ipv4_ip_subnet, ipv4_mask2prefix, ipv4_prefix2mask, ipv4_ptonx, ipv6_addr_type,
- ipv4_ptonx ipaddr

- ipv6_addr_type ipaddr
- ipv6_ip_matches ipaddr prefix
- ipv6_ptonx ipaddr

# DESCRIPTION

## ipv4_ip_subnet
Function checks that IP address is in subnet.
Function checks that IPv4 address is in subnet.

Example:
```
Expand Down Expand Up @@ -133,6 +134,23 @@ done
The intended purpose of *ipv6_addr_type* is to prevent misuse of special-use addresses.
For example, since link-local unicast addresses only make sense within a link and are incomplete without a scope identifier, it generally makes no sense to specify them in DNS AAAA records.

## ipv6_ip_matches
Checks that an IPv6 address is in a prefix (IOW, belongs in a range with common leading bits).

Example:
```
ipv6_ip_matches 3fff:e:b:1::2 3fff:e:b:1::/64; echo res=$?
res=0

ipv6_ip_matches 3fff:e:b:3::2 3fff:e:b:1::/64; echo res=$?
res=1

ipv6_ip_matches 3fff:e:b:3::2 3fff:e:b::/48; echo res=$?
res=0
```

Remember that an IPv6 prefix (netmask of leading 1 bits), unlike an IPv4 prefix, does not necessarily have routing significance; it might or might not be reachable "on-link" in any subnet.

## ipv6_ptonx
This function interprets the given option value as an IPv6 address similarly to inet_pton(3), and outputs each octet in network byte order as 16 adjacent 2-digit hexadecimal numbers.
This form is useful to perform bitwise operations on the address.
Expand Down
54 changes: 53 additions & 1 deletion shell-ip-address
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Expand Up @@ -108,7 +108,7 @@ __len2mask_32()
printf '%s' "$mask"
}

### Checks that IP address is in subnet
### Checks that IPv4 address is in subnet
### Usage example:
### ipv4_ip_subnet 172.16.1.2 172.16.1.0/24; echo res=$?
### res=0
Expand Down Expand Up @@ -345,4 +345,56 @@ ipv6_addr_type()
return 0
}

### Checks that IPv6 address is in a prefix.
### Usage example:
### ipv6_ip_matches 3fff:e:b:1::2 3fff:e:b:1::/64; echo res=$?
### res=0
###
### ipv6_ip_matches 3fff:e:b:3::2 3fff:e:b:1::/64; echo res=$?
### res=1
###
### ipv6_ip_matches 3fff:e:b:3::2 3fff:e:b::/48; echo res=$?
### res=0
ipv6_ip_matches()
{
local addr pref preflen
addr="${1-}"; shift
pref="${1-}"; shift
preflen="${pref##*/}"

[ -n "$preflen" ] ||
return 2
[ "$preflen" = 0 ] || shell_var_is_number "$preflen" ||
return 2
[ "$preflen" -le 128 ] ||
return 2

local hex_addr hex_pref hex_mask

hex_addr="$(ipv6_ptonx "$addr")" &&
hex_pref="$(ipv6_ptonx "${pref%%/*}")" ||
return 2

local i_addr i_pref w_addr w_pref
while [ "$preflen" -gt 32 ]; do
i_addr="${hex_addr#????????}"
i_pref="${hex_pref#????????}"
w_addr="${hex_addr%$i_addr}"
w_pref="${hex_pref%$i_pref}"
[ "$w_pref" = "$w_addr" ] ||
return 1

hex_addr="$i_addr"
hex_pref="$i_pref"
preflen="$(($preflen - 32))"
done
i_addr="${hex_addr#????????}"
i_pref="${hex_pref#????????}"
w_addr="${hex_addr%$i_addr}"
w_pref="${hex_pref%$i_pref}"
hex_mask="$(__len2mask_32 "$preflen")"
[ "$((0x$w_pref & $hex_mask))" -eq "$((0x$w_addr & $hex_mask))" ] ||
return 1
}

fi #__included_shell_ip_address
180 changes: 180 additions & 0 deletions tests/ip_address
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Expand Up @@ -890,3 +890,183 @@ ip_address_test6t21() { # UnitTest
assertFalse "malformed address: $repr" $rc
assertNull "empty output" "$(ipv6_addr_type "$repr")"
}

ip_address_test_match600() { # UnitTest
. ../shell-ip-address

local rc=0
local addr=2001:7::23:443
local prefix=::/0
ipv6_ip_matches "$addr" "$prefix" || rc=1
assertTrue "matches 'default route': $addr" $rc
}

ip_address_test_match602() { # UnitTest
. ../shell-ip-address

local rc=0
local addr=::ffff:c000:2
local prefix=::/64
ipv6_ip_matches "$addr" "$prefix" || rc=1
assertTrue "enough common bits: $addr -> $prefix" $rc
}

ip_address_test_match603() { # UnitTest
. ../shell-ip-address

local rc=0
local addr=::ffff:c000:2
local prefix=::ffff:0:0/96
ipv6_ip_matches "$addr" "$prefix" || rc=1
assertTrue "$addr -> $prefix" $rc
}

ip_address_test_match604() { # UnitTest
. ../shell-ip-address

local rc=0
local addr=2001:db8:7:560a::c000:204
local prefix=2001:db8:7:5608::/61
ipv6_ip_matches "$addr" "$prefix" || rc=1
assertTrue "non-4bit-aligned prefix: $addr -> $prefix" $rc
}

ip_address_test_match605() { # UnitTest
. ../shell-ip-address

local rc=0
local addr=2001:db8:7:560a::c000:204
local prefix=2001:db8:7:5600::/60
ipv6_ip_matches "$addr" "$prefix" || rc=1
assertTrue "non-32bit-aligned prefix: $addr -> $prefix" $rc
}

ip_address_test_match606() { # UnitTest
. ../shell-ip-address

local rc=0
local addr=2001:db8:7:560a::c000:204
local prefix=2001:db8:7:5000::/52
ipv6_ip_matches "$addr" "$prefix" || rc=1
assertTrue "non-32bit-aligned prefix: $addr -> $prefix" $rc
}

ip_address_test_match607() { # UnitTest
. ../shell-ip-address

local rc=0
local addr=2001:db8:7:500a::c000:205
local prefix=2001:db8:7:500a::c000:204/127
ipv6_ip_matches "$addr" "$prefix" || rc=1
assertTrue "127-bit prefix: $addr -> $prefix" $rc
}

ip_address_test_match608() { # UnitTest
. ../shell-ip-address

local rc=0
local addr=2001:db8:7:500a::c000:204
local prefix=2001:db8:7:500a::c000:204/128
ipv6_ip_matches "$addr" "$prefix" || rc=1
assertTrue "128-bit prefix: $addr -> $prefix" $rc
}

ip_address_test_match616() { # UnitTest
. ../shell-ip-address

local rc=0
local addr=3fff:f:e:4::c
local prefix=3fff:f:e:4::/64
ipv6_ip_matches "$addr" "$prefix" || rc=1
assertTrue "$addr -> $prefix" $rc
}

ip_address_test_match617() { # UnitTest
. ../shell-ip-address

local rc=0
local addr=3fff:f:e:4::c
local prefix=3fff:f:e:4::/48
ipv6_ip_matches "$addr" "$prefix" || rc=1
assertTrue "$addr -> $prefix" $rc
}

ip_address_test_match620() { # UnitTest
. ../shell-ip-address

local rc=0
local addr=::ffff:c000:2
local prefix=::/96
ipv6_ip_matches "$addr" "$prefix" || rc=1
assertFalse "common bits too short: $addr -> $prefix" $rc
}

ip_address_test_match621() { # UnitTest
. ../shell-ip-address

local rc=0
local addr=2001::ffff:c000:2
local prefix=::ffff:0:0/96
ipv6_ip_matches "$addr" "$prefix" || rc=1
assertFalse "common low bits: $addr -> $prefix" $rc
}

ip_address_test_match624() { # UnitTest
. ../shell-ip-address

local rc=0
local addr=2001:db8:7:560a::c000:204
local prefix=2001:db8::/60
ipv6_ip_matches "$addr" "$prefix" || rc=1
assertFalse "! $addr -> $prefix" $rc
}

ip_address_test_match636() { # UnitTest
. ../shell-ip-address

local rc=0
local addr=3fff:f:e:4::c
local prefix=3fff:f:e:1::/64
ipv6_ip_matches "$addr" "$prefix" || rc=1
assertFalse "! $addr -> $prefix" $rc
}

ip_address_test_match640() { # UnitTest
. ../shell-ip-address

local rc=0
local addr=xxx
local prefix=2002::/16
ipv6_ip_matches "$addr" "$prefix" || rc=$?
assertEquals "garbage addr: $addr" 2 $rc
}

ip_address_test_match641() { # UnitTest
. ../shell-ip-address

local rc=0
local addr=2001:db8:7:e8::c0
local prefix=yyy/16
ipv6_ip_matches "$addr" "$prefix" || rc=$?
assertEquals "garbage prefix: $prefix" 2 $rc
}

ip_address_test_match642() { # UnitTest
. ../shell-ip-address

local rc=0
local addr=2001:db8:7:e8::c0
local prefix=3fff:1::/zzz
ipv6_ip_matches "$addr" "$prefix" || rc=$?
assertEquals "garbage prefix length: $prefix" 2 $rc
}

ip_address_test_match643() { # UnitTest
. ../shell-ip-address

local rc=0
local addr=2001:db8:7:e8::c0
local prefix=3fff:1::/100500
ipv6_ip_matches "$addr" "$prefix" || rc=$?
assertEquals "garbage prefix length: $prefix" 2 $rc
}