IPv6 Full (Expanded + Compressed) Regex for Go

What this pattern does

This page provides a comprehensive, battle-tested regular expression for matching ipv6 full (expanded + compressed), ported and verified for Go. A rigorously tested regex reduces debugging time and protects your application from edge-case failures. The snippet below is ready to drop into your Go project — whether you're validating in a Gin handler, a gRPC service, or a command-line tool.

Go Implementation

// IPv6 Full (Expanded + Compressed)
// ReDoS-safe | RegexVault — Web & Network > IPv6

package validation

import "regexp"

var ipv6FullExpandedCompressedRe = regexp.MustCompile(`^(([0-9a-fA-F]{1,4}:){7}[0-9a-fA-F]{1,4}|([0-9a-fA-F]{1,4}:){1,7}:|([0-9a-fA-F]{1,4}:){1,6}:[0-9a-fA-F]{1,4}|([0-9a-fA-F]{1,4}:){1,5}(:[0-9a-fA-F]{1,4}){1,2}|([0-9a-fA-F]{1,4}:){1,4}(:[0-9a-fA-F]{1,4}){1,3}|([0-9a-fA-F]{1,4}:){1,3}(:[0-9a-fA-F]{1,4}){1,4}|([0-9a-fA-F]{1,4}:){1,2}(:[0-9a-fA-F]{1,4}){1,5}|[0-9a-fA-F]{1,4}:(:[0-9a-fA-F]{1,4}){1,6}|:(:[0-9a-fA-F]{1,4}){1,7}|::)$`)

func ValidateIpv6FullExpandedCompressed(s string) bool {
    return ipv6FullExpandedCompressedRe.MatchString(s)
}

// Example
// fmt.Println(ValidateIpv6FullExpandedCompressed("2001:db8::1")) // true

Test Cases

When to use this pattern

This pattern is drawn from the Web & Network > IPv6 category and carries a ReDoS-safe certification. That matters for Go developers because Go's RE2 engine is inherently safe from catastrophic backtracking, but this pattern has been additionally verified for correctness. RegexVault audits patterns against known backtracking attack vectors, ensuring you have the necessary context before using this regex in a high-stakes production environment.

Common Pitfalls

Technical Notes

Each alternation handles a specific number of groups before/after ::. The :: can appear at most once (enforced by alternation structure, not lookahead). Go's RE2 may have issues with alternation of this complexity — use net.ParseIP() in Go instead.