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Accept leading zeros in IPv4-mapped IPv6 #568

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Merged
arturobernalg merged 1 commit into from
Oct 11, 2025
Merged

Accept leading zeros in IPv4-mapped IPv6 #568

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9 changes: 7 additions & 2 deletions httpcore5/src/main/java/org/apache/hc/core5/net/InetAddressUtils.java
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Original file line number Diff line number Diff line change
Expand Up @@ -66,8 +66,13 @@ private InetAddressUtils() {
private static final Pattern IPV4_PATTERN =
Pattern.compile("^" + IPV4_BASIC_PATTERN_STRING + "$");

private static final Pattern IPV4_MAPPED_IPV6_PATTERN = // TODO does not allow for redundant leading zeros
Pattern.compile("^::[fF]{4}:" + IPV4_BASIC_PATTERN_STRING + "$");
// Accept IPv4-mapped IPv6, allowing redundant leading zeros in the IPv4 part.
// Examples: ::ffff:1.2.3.4, ::FFFF:001.002.003.004
// Still enforces each octet <= 255 and max 3 digits per octet.
private static final String IPV4_MAPPED_OCTET = "(25[0-5]|2[0-4]\\d|1\\d\\d|0?\\d?\\d)";
private static final Pattern IPV4_MAPPED_IPV6_PATTERN = Pattern.compile("^::[fF]{4}:((" + IPV4_MAPPED_OCTET + ")\\.){3}" + IPV4_MAPPED_OCTET + "$");



private static final Pattern IPV6_STD_PATTERN =
Pattern.compile(
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18 changes: 18 additions & 0 deletions httpcore5/src/test/java/org/apache/hc/core5/net/TestInetAddressUtils.java
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Expand Up @@ -198,4 +198,22 @@ void testInValidIPv4MappedIPv6Address() {
Assertions.assertFalse(InetAddressUtils.isIPv4MappedIPv6("::ffff:1:2:3:4"));
}

@Test
void testValidIPv4MappedIPv6AddressWithLeadingZeros() {
Assertions.assertTrue(InetAddressUtils.isIPv4MappedIPv6("::ffff:001.002.003.004"));
Assertions.assertTrue(InetAddressUtils.isIPv4MappedIPv6("::FFFF:000.000.000.255"));
Assertions.assertTrue(InetAddressUtils.isIPv4MappedIPv6("::ffff:010.020.030.040"));
}

@Test
void testInvalidIPv4MappedIPv6AddressWithBadOctets() {
// >255 not allowed
Assertions.assertFalse(InetAddressUtils.isIPv4MappedIPv6("::ffff:256.000.000.000"));
// too few octets
Assertions.assertFalse(InetAddressUtils.isIPv4MappedIPv6("::ffff:01.02.03"));
// too many digits in an octet (4 digits)
Assertions.assertFalse(InetAddressUtils.isIPv4MappedIPv6("::ffff:0255.000.000.000"));
}


}