golang.org/x/net v0.17.0: publicsuffix.PublicSuffix, publicsuffix.EffectiveTLDPlusOne, publicsuffix.List

Clean-room public code sample — generation instructions

Write a brand-new, minimal, self-contained code sample in this clean-room directory.
Do not copy, paraphrase, or reference any existing project source. Work only from this spec.

A csx.json manifest scaffold already exists. Do not recreate it from memory. Preserve its case.goal, packages and symbols; fill its empty case.contract with exact assertions and correct its environment, commands and verifierAdapter for the files you generate.

Goal: verify pkg:golang/golang.org/x/net@v0.17.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/golang.org/x/net@v0.17.0

Rules:
  - One focused purpose; the smallest project that proves the goal.
  - Include a contract test (test/contract.*) that runs OFFLINE and exits 0 exactly when the goal behavior works.
  - Pin every dependency with a lockfile so resolution is reproducible.
  - No secrets, credentials, or tokens. No real URLs (only example.com or localhost). No absolute paths.
  - No personal names, emails, company names, or project identifiers of any kind.
  - No binaries and no generated output (node_modules, dist, target, venv, .git, .env).
  - Keep it under 200 files and 256KB packed.

{"case":{"caseId":"case:sha256:16118ebb8e63d624113c4e9208ab3f047cf46be2acf87e5adcafb9627e0844bc","contract":["publicsuffix.PublicSuffix extracts the public suffix and indicates if it is managed by ICANN for domain names","publicsuffix.EffectiveTLDPlusOne extracts the effective top-level domain plus one label, or returns an error for invalid domains and bare public suffixes","publicsuffix.List implements the PublicSuffixList interface for cookie domain validation"],"goal":"verify pkg:golang/golang.org/x/net@v0.17.0","kind":"HOW","packages":["pkg:golang/golang.org/x/net@v0.17.0"],"schemaVersion":1,"symbols":["golang.org/x/net/publicsuffix.PublicSuffix","golang.org/x/net/publicsuffix.EffectiveTLDPlusOne","golang.org/x/net/publicsuffix.List"]},"contractCommand":["go","run","./test"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"golang","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"go","schemaVersion":1},"license":"MIT-0","packages":["pkg:golang/golang.org/x/net@v0.17.0"],"schemaVersion":1,"subject":"pkg:golang/golang.org/x/net@v0.17.0","symbols":["golang.org/x/net/publicsuffix.PublicSuffix","golang.org/x/net/publicsuffix.EffectiveTLDPlusOne","golang.org/x/net/publicsuffix.List"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.22

require golang.org/x/net v0.17.0

golang.org/x/net v0.17.0 h1:pVaXccu2ozPjCXewfr1S7xza/zcXTity9cCdXQYSjIM=
golang.org/x/net v0.17.0/go.mod h1:NxSsAGuq816PNPmqtQdLE42eU2Fs7NoRIZrHJAlaCOE=

package main

import (
	"fmt"
	"log"

	"golang.org/x/net/publicsuffix"
)

func main() {
	// 1. Determine Public Suffix and ICANN status
	domain := "subdomain.example.co.uk"
	suffix, icann := publicsuffix.PublicSuffix(domain)
	fmt.Printf("Domain: %s -> Public Suffix: %s (ICANN: %v)\n", domain, suffix, icann)

	// 2. Extract Effective TLD + 1 (eTLD+1)
	etldPlusOne, err := publicsuffix.EffectiveTLDPlusOne(domain)
	if err != nil {
		log.Fatalf("failed to extract eTLD+1: %v", err)
	}
	fmt.Printf("Domain: %s -> eTLD+1: %s\n", domain, etldPlusOne)

	// 3. Use PublicSuffixList interface
	cookieDomainSuffix := publicsuffix.List.PublicSuffix("api.service.org")
	fmt.Printf("Cookie Domain Suffix: %s\n", cookieDomainSuffix)

	fmt.Println("golang.org/x/net/publicsuffix sample completed successfully")
}

{
  "schemaVersion": 1,
  "goal": "verify pkg:golang/golang.org/x/net@v0.17.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/golang.org/x/net@v0.17.0"
  ]
}

package main

import (
	"fmt"
	"os"

	"golang.org/x/net/publicsuffix"
)

func main() {
	// Assertion 1: publicsuffix.PublicSuffix extracts the public suffix and indicates if it is managed by ICANN for domain names
	{
		testCases := []struct {
			domain     string
			wantSuffix string
			wantICANN  bool
		}{
			{"example.com", "com", true},
			{"foo.example.co.uk", "co.uk", true},
			{"golang.org", "org", true},
			{"myproject.github.io", "github.io", false},
			{"customblog.blogspot.com", "blogspot.com", false},
			{"localhost", "localhost", false},
		}

		for _, tc := range testCases {
			gotSuffix, gotICANN := publicsuffix.PublicSuffix(tc.domain)
			if gotSuffix != tc.wantSuffix || gotICANN != tc.wantICANN {
				fmt.Fprintf(os.Stderr, "assertion 1 failed for %q: got (%q, %v), want (%q, %v)\n",
					tc.domain, gotSuffix, gotICANN, tc.wantSuffix, tc.wantICANN)
				os.Exit(1)
			}
		}
	}

	// Assertion 2: publicsuffix.EffectiveTLDPlusOne extracts the effective top-level domain plus one label, or returns an error for invalid domains and bare public suffixes
	{
		validCases := []struct {
			domain  string
			wantDom string
		}{
			{"example.com", "example.com"},
			{"sub.example.com", "example.com"},
			{"a.b.c.example.co.uk", "example.co.uk"},
			{"foo.github.io", "foo.github.io"},
			{"sub.foo.github.io", "foo.github.io"},
		}

		for _, tc := range validCases {
			gotDom, err := publicsuffix.EffectiveTLDPlusOne(tc.domain)
			if err != nil {
				fmt.Fprintf(os.Stderr, "assertion 2 failed for %q: unexpected error: %v\n", tc.domain, err)
				os.Exit(1)
			}
			if gotDom != tc.wantDom {
				fmt.Fprintf(os.Stderr, "assertion 2 failed for %q: got %q, want %q\n", tc.domain, gotDom, tc.wantDom)
				os.Exit(1)
			}
		}

		invalidCases := []string{
			"com",
			"co.uk",
			"github.io",
			"",
			".",
			"..",
		}

		for _, inv := range invalidCases {
			gotDom, err := publicsuffix.EffectiveTLDPlusOne(inv)
			if err == nil {
				fmt.Fprintf(os.Stderr, "assertion 2 failed for invalid domain %q: expected error, got %q\n", inv, gotDom)
				os.Exit(1)
			}
		}
	}

	// Assertion 3: publicsuffix.List implements the PublicSuffixList interface for cookie domain validation
	{
		if publicsuffix.List == nil {
			fmt.Fprintf(os.Stderr, "assertion 3 failed: publicsuffix.List is nil\n")
			os.Exit(1)
		}

		ps := publicsuffix.List.PublicSuffix("sub.example.com")
		if ps != "com" {
			fmt.Fprintf(os.Stderr, "assertion 3 failed: List.PublicSuffix got %q, want %q\n", ps, "com")
			os.Exit(1)
		}

		psUK := publicsuffix.List.PublicSuffix("deep.nested.domain.co.uk")
		if psUK != "co.uk" {
			fmt.Fprintf(os.Stderr, "assertion 3 failed: List.PublicSuffix got %q, want %q\n", psUK, "co.uk")
			os.Exit(1)
		}

		str := publicsuffix.List.String()
		if str == "" {
			fmt.Fprintf(os.Stderr, "assertion 3 failed: List.String returned empty string\n")
			os.Exit(1)
		}
	}

	fmt.Println("PASS: pkg:golang/golang.org/x/net@v0.17.0 contract passed")
}