github.com/caddyserver/certmagic v0.23.0: SubjectQualifiesForPublicCert

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 github.com/caddyserver/certmagic.SubjectQualifiesForPublicCert in pkg:golang/github.com/caddyserver/certmagic@v0.23.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/caddyserver/certmagic@v0.23.0
Demonstrate these symbols/APIs:
  - github.com/caddyserver/certmagic.SubjectQualifiesForPublicCert
Constraints:
  - executionContext: node
Required runtime conditions:
  - ecosystem: npm
  - language: javascript
  - moduleSystem: cjs
  - packageManager: npm@10.9.8
  - runtime: node@22.23.2

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:e435235b1ee8074cc13051da6be293dabe0182d5b0d84183f8f9d34cb4cd3f0e","contract":["SubjectQualifiesForPublicCert returns true for public fully qualified domain names","SubjectQualifiesForPublicCert returns true for valid leftmost wildcard domain names with three or more labels","SubjectQualifiesForPublicCert returns false for empty or whitespace-only subject names","SubjectQualifiesForPublicCert returns false for localhost and .localhost domain names","SubjectQualifiesForPublicCert returns false for internal domain names with suffixes like .local, .internal, and .home.arpa","SubjectQualifiesForPublicCert returns false for private and loopback IPv4 and IPv6 addresses","SubjectQualifiesForPublicCert returns true for public IPv4 addresses","SubjectQualifiesForPublicCert returns false for invalid wildcard placements or multiple wildcards","SubjectQualifiesForPublicCert returns false for subject names with leading dots, trailing dots, or invalid characters"],"goal":"verify github.com/caddyserver/certmagic.SubjectQualifiesForPublicCert in pkg:golang/github.com/caddyserver/certmagic@v0.23.0","kind":"HOW","packages":["pkg:golang/github.com/caddyserver/certmagic@v0.23.0"],"schemaVersion":1,"symbols":["github.com/caddyserver/certmagic.SubjectQualifiesForPublicCert"]},"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/github.com/caddyserver/certmagic@v0.23.0"],"schemaVersion":1,"subject":"pkg:golang/github.com/caddyserver/certmagic@v0.23.0","symbols":["github.com/caddyserver/certmagic.SubjectQualifiesForPublicCert"],"verifierAdapter":"golang@1"}

module sample

go 1.26.6

require github.com/caddyserver/certmagic v0.23.0

require (
	github.com/caddyserver/zerossl v0.1.3 // indirect
	github.com/klauspost/cpuid/v2 v2.2.10 // indirect
	github.com/libdns/libdns v1.0.0-beta.1 // indirect
	github.com/mholt/acmez/v3 v3.1.2 // indirect
	github.com/miekg/dns v1.1.63 // indirect
	github.com/zeebo/blake3 v0.2.4 // indirect
	go.uber.org/multierr v1.11.0 // indirect
	go.uber.org/zap v1.27.0 // indirect
	go.uber.org/zap/exp v0.3.0 // indirect
	golang.org/x/crypto v0.36.0 // indirect
	golang.org/x/mod v0.24.0 // indirect
	golang.org/x/net v0.37.0 // indirect
	golang.org/x/sync v0.12.0 // indirect
	golang.org/x/sys v0.31.0 // indirect
	golang.org/x/text v0.23.0 // indirect
	golang.org/x/tools v0.31.0 // indirect
)

github.com/caddyserver/certmagic v0.23.0 h1:CfpZ/50jMfG4+1J/u2LV6piJq4HOfO6ppOnOf7DkFEU=
github.com/caddyserver/certmagic v0.23.0/go.mod h1:9mEZIWqqWoI+Gf+4Trh04MOVPD0tGSxtqsxg87hAIH4=
github.com/caddyserver/zerossl v0.1.3 h1:onS+pxp3M8HnHpN5MMbOMyNjmTheJyWRaZYwn+YTAyA=
github.com/caddyserver/zerossl v0.1.3/go.mod h1:CxA0acn7oEGO6//4rtrRjYgEoa4MFw/XofZnrYwGqG4=
github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
github.com/klauspost/cpuid/v2 v2.2.10 h1:tBs3QSyvjDyFTq3uoc/9xFpCuOsJQFNPiAhYdw2skhE=
github.com/klauspost/cpuid/v2 v2.2.10/go.mod h1:hqwkgyIinND0mEev00jJYCxPNVRVXFQeu1XKlok6oO0=
github.com/libdns/libdns v1.0.0-beta.1 h1:KIf4wLfsrEpXpZ3vmc/poM8zCATXT2klbdPe6hyOBjQ=
github.com/libdns/libdns v1.0.0-beta.1/go.mod h1:4Bj9+5CQiNMVGf87wjX4CY3HQJypUHRuLvlsfsZqLWQ=
github.com/mholt/acmez/v3 v3.1.2 h1:auob8J/0FhmdClQicvJvuDavgd5ezwLBfKuYmynhYzc=
github.com/mholt/acmez/v3 v3.1.2/go.mod h1:L1wOU06KKvq7tswuMDwKdcHeKpFFgkppZy/y0DFxagQ=
github.com/miekg/dns v1.1.63 h1:8M5aAw6OMZfFXTT7K5V0Eu5YiiL8l7nUAkyN6C9YwaY=
github.com/miekg/dns v1.1.63/go.mod h1:6NGHfjhpmr5lt3XPLuyfDJi5AXbNIPM9PY6H6sF1Nfs=
github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
github.com/stretchr/testify v1.8.1 h1:w7B6lhMri9wdJUVmEZPGGhZzrYTPvgJArz7wNPgYKsk=
github.com/stretchr/testify v1.8.1/go.mod h1:w2LPCIKwWwSfY2zedu0+kehJoqGctiVI29o6fzry7u4=
github.com/zeebo/assert v1.1.0 h1:hU1L1vLTHsnO8x8c9KAR5GmM5QscxHg5RNU5z5qbUWY=
github.com/zeebo/assert v1.1.0/go.mod h1:Pq9JiuJQpG8JLJdtkwrJESF0Foym2/D9XMU5ciN/wJ0=
github.com/zeebo/blake3 v0.2.4 h1:KYQPkhpRtcqh0ssGYcKLG1JYvddkEA8QwCM/yBqhaZI=
github.com/zeebo/blake3 v0.2.4/go.mod h1:7eeQ6d2iXWRGF6npfaxl2CU+xy2Fjo2gxeyZGCRUjcE=
github.com/zeebo/pcg v1.0.1 h1:lyqfGeWiv4ahac6ttHs+I5hwtH/+1mrhlCtVNQM2kHo=
github.com/zeebo/pcg v1.0.1/go.mod h1:09F0S9iiKrwn9rlI5yjLkmrug154/YRW6KnnXVDM/l4=
go.uber.org/goleak v1.3.0 h1:2K3zAYmnTNqV73imy9J1T3WC+gmCePx2hEGkimedGto=
go.uber.org/goleak v1.3.0/go.mod h1:CoHD4mav9JJNrW/WLlf7HGZPjdw8EucARQHekz1X6bE=
go.uber.org/multierr v1.11.0 h1:blXXJkSxSSfBVBlC76pxqeO+LN3aDfLQo+309xJstO0=
go.uber.org/multierr v1.11.0/go.mod h1:20+QtiLqy0Nd6FdQB9TLXag12DsQkrbs3htMFfDN80Y=
go.uber.org/zap v1.27.0 h1:aJMhYGrd5QSmlpLMr2MftRKl7t8J8PTZPA732ud/XR8=
go.uber.org/zap v1.27.0/go.mod h1:GB2qFLM7cTU87MWRP2mPIjqfIDnGu+VIO4V/SdhGo2E=
go.uber.org/zap/exp v0.3.0 h1:6JYzdifzYkGmTdRR59oYH+Ng7k49H9qVpWwNSsGJj3U=
go.uber.org/zap/exp v0.3.0/go.mod h1:5I384qq7XGxYyByIhHm6jg5CHkGY0nsTfbDLgDDlgJQ=
golang.org/x/crypto v0.36.0 h1:AnAEvhDddvBdpY+uR+MyHmuZzzNqXSe/GvuDeob5L34=
golang.org/x/crypto v0.36.0/go.mod h1:Y4J0ReaxCR1IMaabaSMugxJES1EpwhBHhv2bDHklZvc=
golang.org/x/mod v0.24.0 h1:ZfthKaKaT4NrhGVZHO1/WDTwGES4De8KtWO0SIbNJMU=
golang.org/x/mod v0.24.0/go.mod h1:IXM97Txy2VM4PJ3gI61r1YEk/gAj6zAHN3AdZt6S9Ww=
golang.org/x/net v0.37.0 h1:1zLorHbz+LYj7MQlSf1+2tPIIgibq2eL5xkrGk6f+2c=
golang.org/x/net v0.37.0/go.mod h1:ivrbrMbzFq5J41QOQh0siUuly180yBYtLp+CKbEaFx8=
golang.org/x/sync v0.12.0 h1:MHc5BpPuC30uJk597Ri8TV3CNZcTLu6B6z4lJy+g6Jw=
golang.org/x/sync v0.12.0/go.mod h1:1dzgHSNfp02xaA81J2MS99Qcpr2w7fw1gpm99rleRqA=
golang.org/x/sys v0.31.0 h1:ioabZlmFYtWhL+TRYpcnNlLwhyxaM9kWTDEmfnprqik=
golang.org/x/sys v0.31.0/go.mod h1:BJP2sWEmIv4KK5OTEluFJCKSidICx8ciO85XgH3Ak8k=
golang.org/x/text v0.23.0 h1:D71I7dUrlY+VX0gQShAThNGHFxZ13dGLBHQLVl1mJlY=
golang.org/x/text v0.23.0/go.mod h1:/BLNzu4aZCJ1+kcD0DNRotWKage4q2rGVAg4o22unh4=
golang.org/x/tools v0.31.0 h1:0EedkvKDbh+qistFTd0Bcwe/YLh4vHwWEkiI0toFIBU=
golang.org/x/tools v0.31.0/go.mod h1:naFTU+Cev749tSJRXJlna0T3WxKvb1kWEx15xA4SdmQ=
gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

package main

import (
	"fmt"

	"github.com/caddyserver/certmagic"
)

// CheckSubjectEligibility checks if the given hostname or IP qualifies for public CA certificate issuance.
func CheckSubjectEligibility(subject string) bool {
	return certmagic.SubjectQualifiesForPublicCert(subject)
}

func main() {
	subjects := []string{
		"example.com",
		"*.example.com",
		"localhost",
		"127.0.0.1",
		"internal.local",
	}

	for _, subj := range subjects {
		eligible := CheckSubjectEligibility(subj)
		fmt.Printf("Subject %q eligible for public cert: %v\n", subj, eligible)
	}
}

{
  "schemaVersion": 1,
  "goal": "verify github.com/caddyserver/certmagic.SubjectQualifiesForPublicCert in pkg:golang/github.com/caddyserver/certmagic@v0.23.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/caddyserver/certmagic@v0.23.0"
  ],
  "symbols": [
    "github.com/caddyserver/certmagic.SubjectQualifiesForPublicCert"
  ],
  "constraints": {
    "executionContext": "node"
  },
  "runtimeConditions": {
    "ecosystem": "npm",
    "language": "javascript",
    "moduleSystem": "cjs",
    "packageManager": "npm@10.9.8",
    "runtime": "node@22.23.2"
  }
}

package main

import (
	"fmt"
	"os"

	"github.com/caddyserver/certmagic"
)

func main() {
	// Assertion 1: SubjectQualifiesForPublicCert returns true for public fully qualified domain names
	publicDomains := []string{"example.com", "sub.example.com", "api.service.example.org"}
	for _, domain := range publicDomains {
		if !certmagic.SubjectQualifiesForPublicCert(domain) {
			fmt.Fprintf(os.Stderr, "assertion 1 failed: expected true for public domain %q\n", domain)
			os.Exit(1)
		}
	}

	// Assertion 2: SubjectQualifiesForPublicCert returns true for valid leftmost wildcard domain names with three or more labels
	validWildcards := []string{"*.example.com", "*.sub.example.com"}
	for _, wildcard := range validWildcards {
		if !certmagic.SubjectQualifiesForPublicCert(wildcard) {
			fmt.Fprintf(os.Stderr, "assertion 2 failed: expected true for valid wildcard %q\n", wildcard)
			os.Exit(1)
		}
	}

	// Assertion 3: SubjectQualifiesForPublicCert returns false for empty or whitespace-only subject names
	emptyNames := []string{"", "   ", "\t\n"}
	for _, name := range emptyNames {
		if certmagic.SubjectQualifiesForPublicCert(name) {
			fmt.Fprintf(os.Stderr, "assertion 3 failed: expected false for empty/whitespace name %q\n", name)
			os.Exit(1)
		}
	}

	// Assertion 4: SubjectQualifiesForPublicCert returns false for localhost and .localhost domain names
	localhostNames := []string{"localhost", "sub.localhost", "app.localhost"}
	for _, name := range localhostNames {
		if certmagic.SubjectQualifiesForPublicCert(name) {
			fmt.Fprintf(os.Stderr, "assertion 4 failed: expected false for localhost name %q\n", name)
			os.Exit(1)
		}
	}

	// Assertion 5: SubjectQualifiesForPublicCert returns false for internal domain names with suffixes like .local, .internal, and .home.arpa
	internalDomains := []string{"service.local", "db.internal", "router.home.arpa"}
	for _, name := range internalDomains {
		if certmagic.SubjectQualifiesForPublicCert(name) {
			fmt.Fprintf(os.Stderr, "assertion 5 failed: expected false for internal domain %q\n", name)
			os.Exit(1)
		}
	}

	// Assertion 6: SubjectQualifiesForPublicCert returns false for private and loopback IPv4 and IPv6 addresses
	internalIPs := []string{"127.0.0.1", "10.0.0.1", "172.16.0.1", "192.168.1.1", "::1", "fe80::1"}
	for _, ip := range internalIPs {
		if certmagic.SubjectQualifiesForPublicCert(ip) {
			fmt.Fprintf(os.Stderr, "assertion 6 failed: expected false for private/loopback IP %q\n", ip)
			os.Exit(1)
		}
	}

	// Assertion 7: SubjectQualifiesForPublicCert returns true for public IPv4 addresses
	publicIPs := []string{"8.8.8.8", "203.0.113.1"}
	for _, ip := range publicIPs {
		if !certmagic.SubjectQualifiesForPublicCert(ip) {
			fmt.Fprintf(os.Stderr, "assertion 7 failed: expected true for public IP %q\n", ip)
			os.Exit(1)
		}
	}

	// Assertion 8: SubjectQualifiesForPublicCert returns false for invalid wildcard placements or multiple wildcards
	invalidWildcards := []string{"*", "*.com", "*.*.example.com", "sub.*.example.com", "example*.com"}
	for _, wildcard := range invalidWildcards {
		if certmagic.SubjectQualifiesForPublicCert(wildcard) {
			fmt.Fprintf(os.Stderr, "assertion 8 failed: expected false for invalid wildcard %q\n", wildcard)
			os.Exit(1)
		}
	}

	// Assertion 9: SubjectQualifiesForPublicCert returns false for subject names with leading dots, trailing dots, or invalid characters
	invalidNames := []string{".example.com", "example.com.", "exam ple.com", "example;test.com"}
	for _, name := range invalidNames {
		if certmagic.SubjectQualifiesForPublicCert(name) {
			fmt.Fprintf(os.Stderr, "assertion 9 failed: expected false for invalid subject name %q\n", name)
			os.Exit(1)
		}
	}

	fmt.Println("All SubjectQualifiesForPublicCert contract assertions passed.")
}