caddytls: Upgrade ACMEz to v2; support ZeroSSL API; various fixes (#6229)

* WIP: acmez v2, CertMagic, and ZeroSSL issuer upgrades

* caddytls: ZeroSSLIssuer now uses ZeroSSL API instead of ACME

* Fix go.mod

* caddytls: Fix automation related to managers (fix #6060)

* Fix typo (appease linter)

* Fix HTTP validation with ZeroSSL API

3 files changed, 41 insertions, 24 deletions

diff --git a/caddyconfig/httpcaddyfile/builtins.go b/caddyconfig/httpcaddyfile/builtins.go
index 505885d2d..a7f4247f5 100644
--- a/caddyconfig/httpcaddyfile/builtins.go
+++ b/caddyconfig/httpcaddyfile/builtins.go
@@ -24,7 +24,7 @@ import (
 	"time"
 
 	"github.com/caddyserver/certmagic"
-	"github.com/mholt/acmez/acme"
+	"github.com/mholt/acmez/v2/acme"
 	"go.uber.org/zap/zapcore"
 
 	"github.com/caddyserver/caddy/v2"
@@ -107,7 +107,6 @@ func parseTLS(h Helper) ([]ConfigValue, error) {
 	var onDemand bool
 	var reusePrivateKeys bool
 
-	// file certificate loader
 	firstLine := h.RemainingArgs()
 	switch len(firstLine) {
 	case 0:
@@ -117,13 +116,13 @@ func parseTLS(h Helper) ([]ConfigValue, error) {
 		} else if !strings.Contains(firstLine[0], "@") {
 			return nil, h.Err("single argument must either be 'internal' or an email address")
 		} else {
-			if acmeIssuer == nil {
-				acmeIssuer = new(caddytls.ACMEIssuer)
+			acmeIssuer = &caddytls.ACMEIssuer{
+				Email: firstLine[0],
 			}
-			acmeIssuer.Email = firstLine[0]
 		}
 
 	case 2:
+		// file certificate loader
 		certFilename := firstLine[0]
 		keyFilename := firstLine[1]
 
@@ -488,19 +487,24 @@ func parseTLS(h Helper) ([]ConfigValue, error) {
 
 	case acmeIssuer != nil:
 		// implicit ACME issuers (from various subdirectives) - use defaults; there might be more than one
-		defaultIssuers := caddytls.DefaultIssuers()
+		defaultIssuers := caddytls.DefaultIssuers(acmeIssuer.Email)
 
-		// if a CA endpoint was set, override multiple implicit issuers since it's a specific one
+		// if an ACME CA endpoint was set, the user expects to use that specific one,
+		// not any others that may be defaults, so replace all defaults with that ACME CA
 		if acmeIssuer.CA != "" {
 			defaultIssuers = []certmagic.Issuer{acmeIssuer}
 		}
 
 		for _, issuer := range defaultIssuers {
-			switch iss := issuer.(type) {
-			case *caddytls.ACMEIssuer:
-				issuer = acmeIssuer
-			case *caddytls.ZeroSSLIssuer:
-				iss.ACMEIssuer = acmeIssuer
+			// apply settings from the implicitly-configured ACMEIssuer to any
+			// default ACMEIssuers, but preserve each default issuer's CA endpoint,
+			// because, for example, if you configure the DNS challenge, it should
+			// apply to any of the default ACMEIssuers, but you don't want to trample
+			// out their unique CA endpoints
+			if iss, ok := issuer.(*caddytls.ACMEIssuer); ok && iss != nil {
+				acmeCopy := *acmeIssuer
+				acmeCopy.CA = iss.CA
+				issuer = &acmeCopy
 			}
 			configVals = append(configVals, ConfigValue{
 				Class: "tls.cert_issuer",
diff --git a/caddyconfig/httpcaddyfile/options.go b/caddyconfig/httpcaddyfile/options.go
index 70d475d6b..bbc63ced8 100644
--- a/caddyconfig/httpcaddyfile/options.go
+++ b/caddyconfig/httpcaddyfile/options.go
@@ -18,7 +18,7 @@ import (
 	"strconv"
 
 	"github.com/caddyserver/certmagic"
-	"github.com/mholt/acmez/acme"
+	"github.com/mholt/acmez/v2/acme"
 
 	"github.com/caddyserver/caddy/v2"
 	"github.com/caddyserver/caddy/v2/caddyconfig"
@@ -212,9 +212,9 @@ func parseOptACMEDNS(d *caddyfile.Dispenser, _ any) (any, error) {
 	if err != nil {
 		return nil, err
 	}
-	prov, ok := unm.(certmagic.ACMEDNSProvider)
+	prov, ok := unm.(certmagic.DNSProvider)
 	if !ok {
-		return nil, d.Errf("module %s (%T) is not a certmagic.ACMEDNSProvider", modID, unm)
+		return nil, d.Errf("module %s (%T) is not a certmagic.DNSProvider", modID, unm)
 	}
 	return prov, nil
 }
diff --git a/caddyconfig/httpcaddyfile/tlsapp.go b/caddyconfig/httpcaddyfile/tlsapp.go
index 1adb2b6e0..08da3a5c7 100644
--- a/caddyconfig/httpcaddyfile/tlsapp.go
+++ b/caddyconfig/httpcaddyfile/tlsapp.go
@@ -24,7 +24,7 @@ import (
 	"strings"
 
 	"github.com/caddyserver/certmagic"
-	"github.com/mholt/acmez/acme"
+	"github.com/mholt/acmez/v2/acme"
 
 	"github.com/caddyserver/caddy/v2"
 	"github.com/caddyserver/caddy/v2/caddyconfig"
@@ -224,7 +224,7 @@ func (st ServerType) buildTLSApp(
 				var internal, external []string
 				for _, s := range ap.SubjectsRaw {
 					// do not create Issuers for Tailscale domains; they will be given a Manager instead
-					if strings.HasSuffix(strings.ToLower(s), ".ts.net") {
+					if isTailscaleDomain(s) {
 						continue
 					}
 					if !certmagic.SubjectQualifiesForCert(s) {
@@ -378,15 +378,12 @@ func (st ServerType) buildTLSApp(
 				if len(ap.Issuers) == 0 && automationPolicyHasAllPublicNames(ap) {
 					// for public names, create default issuers which will later be filled in with configured global defaults
 					// (internal names will implicitly use the internal issuer at auto-https time)
-					ap.Issuers = caddytls.DefaultIssuers()
+					emailStr, _ := globalEmail.(string)
+					ap.Issuers = caddytls.DefaultIssuers(emailStr)
 
 					// if a specific endpoint is configured, can't use multiple default issuers
 					if globalACMECA != nil {
-						if strings.Contains(globalACMECA.(string), "zerossl") {
-							ap.Issuers = []certmagic.Issuer{&caddytls.ZeroSSLIssuer{ACMEIssuer: new(caddytls.ACMEIssuer)}}
-						} else {
-							ap.Issuers = []certmagic.Issuer{new(caddytls.ACMEIssuer)}
-						}
+						ap.Issuers = []certmagic.Issuer{new(caddytls.ACMEIssuer)}
 					}
 				}
 			}
@@ -666,17 +663,33 @@ func automationPolicyShadows(i int, aps []*caddytls.AutomationPolicy) int {
 // subjectQualifiesForPublicCert is like certmagic.SubjectQualifiesForPublicCert() except
 // that this allows domains with multiple wildcard levels like '*.*.example.com' to qualify
 // if the automation policy has OnDemand enabled (i.e. this function is more lenient).
+//
+// IP subjects are considered as non-qualifying for public certs. Technically, there are
+// now public ACME CAs as well as non-ACME CAs that issue IP certificates. But this function
+// is used solely for implicit automation (defaults), where it gets really complicated to
+// keep track of which issuers support IP certificates in which circumstances. Currently,
+// issuers that support IP certificates are very few, and all require some sort of config
+// from the user anyway (such as an account credential). Since we cannot implicitly and
+// automatically get public IP certs without configuration from the user, we treat IPs as
+// not qualifying for public certificates. Users should expressly configure an issuer
+// that supports IP certs for that purpose.
 func subjectQualifiesForPublicCert(ap *caddytls.AutomationPolicy, subj string) bool {
 	return !certmagic.SubjectIsIP(subj) &&
 		!certmagic.SubjectIsInternal(subj) &&
 		(strings.Count(subj, "*.") < 2 || ap.OnDemand)
 }
 
+// automationPolicyHasAllPublicNames returns true if all the names on the policy
+// do NOT qualify for public certs OR are tailscale domains.
 func automationPolicyHasAllPublicNames(ap *caddytls.AutomationPolicy) bool {
 	for _, subj := range ap.SubjectsRaw {
-		if !subjectQualifiesForPublicCert(ap, subj) {
+		if !subjectQualifiesForPublicCert(ap, subj) || isTailscaleDomain(subj) {
 			return false
 		}
 	}
 	return true
 }
+
+func isTailscaleDomain(name string) bool {
+	return strings.HasSuffix(strings.ToLower(name), ".ts.net")
+}