test: Improve layout of helper binaries

This patch moves the test helper binaries to a "one directory per
helper" layout, and also makes them to be ignored in the coverage build
instead of all builds.

With this change, "go build ./..." will build all binaries including the
test helpers, which helps make sure that module manage automation also
considers them. In particular, this makes "go mod tidy" work fine.

test/util/generate_cert/generate_cert.go

@@ -0,0 +1,168 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build !coverage
+// +build !coverage
+
+// Generate a self-signed X.509 certificate for a TLS server. Outputs to
+// 'cert.pem' and 'key.pem' and will overwrite existing files.
+
+package main
+
+import (
+	"crypto/ecdsa"
+	"crypto/elliptic"
+	"crypto/rand"
+	"crypto/rsa"
+	"crypto/x509"
+	"crypto/x509/pkix"
+	"encoding/pem"
+	"flag"
+	"fmt"
+	"log"
+	"math/big"
+	"net"
+	"os"
+	"strings"
+	"time"
+
+	"golang.org/x/net/idna"
+)
+
+var (
+	host       = flag.String("host", "", "Comma-separated hostnames and IPs to generate a certificate for")
+	validFrom  = flag.String("start-date", "", "Creation date formatted as Jan 1 15:04:05 2011")
+	validFor   = flag.Duration("duration", 365*24*time.Hour, "Duration that certificate is valid for")
+	isCA       = flag.Bool("ca", false, "whether this cert should be its own Certificate Authority")
+	rsaBits    = flag.Int("rsa-bits", 2048, "Size of RSA key to generate. Ignored if --ecdsa-curve is set")
+	ecdsaCurve = flag.String("ecdsa-curve", "", "ECDSA curve to use to generate a key. Valid values are P224, P256, P384, P521")
+)
+
+func publicKey(priv interface{}) interface{} {
+	switch k := priv.(type) {
+	case *rsa.PrivateKey:
+		return &k.PublicKey
+	case *ecdsa.PrivateKey:
+		return &k.PublicKey
+	default:
+		return nil
+	}
+}
+
+func pemBlockForKey(priv interface{}) *pem.Block {
+	switch k := priv.(type) {
+	case *rsa.PrivateKey:
+		return &pem.Block{Type: "RSA PRIVATE KEY", Bytes: x509.MarshalPKCS1PrivateKey(k)}
+	case *ecdsa.PrivateKey:
+		b, err := x509.MarshalECPrivateKey(k)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "Unable to marshal ECDSA private key: %v", err)
+			os.Exit(2)
+		}
+		return &pem.Block{Type: "EC PRIVATE KEY", Bytes: b}
+	default:
+		return nil
+	}
+}
+
+func main() {
+	flag.Parse()
+
+	if len(*host) == 0 {
+		log.Fatalf("Missing required --host parameter")
+	}
+
+	var priv interface{}
+	var err error
+	switch *ecdsaCurve {
+	case "":
+		priv, err = rsa.GenerateKey(rand.Reader, *rsaBits)
+	case "P224":
+		priv, err = ecdsa.GenerateKey(elliptic.P224(), rand.Reader)
+	case "P256":
+		priv, err = ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
+	case "P384":
+		priv, err = ecdsa.GenerateKey(elliptic.P384(), rand.Reader)
+	case "P521":
+		priv, err = ecdsa.GenerateKey(elliptic.P521(), rand.Reader)
+	default:
+		fmt.Fprintf(os.Stderr, "Unrecognized elliptic curve: %q", *ecdsaCurve)
+		os.Exit(1)
+	}
+	if err != nil {
+		log.Fatalf("failed to generate private key: %s", err)
+	}
+
+	var notBefore time.Time
+	if len(*validFrom) == 0 {
+		notBefore = time.Now()
+	} else {
+		notBefore, err = time.Parse("Jan 2 15:04:05 2006", *validFrom)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "Failed to parse creation date: %s\n", err)
+			os.Exit(1)
+		}
+	}
+
+	notAfter := notBefore.Add(*validFor)
+
+	serialNumberLimit := new(big.Int).Lsh(big.NewInt(1), 128)
+	serialNumber, err := rand.Int(rand.Reader, serialNumberLimit)
+	if err != nil {
+		log.Fatalf("failed to generate serial number: %s", err)
+	}
+
+	template := x509.Certificate{
+		SerialNumber: serialNumber,
+		Subject: pkix.Name{
+			Organization: []string{"Acme Co"},
+		},
+		NotBefore: notBefore,
+		NotAfter:  notAfter,
+
+		KeyUsage:              x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature,
+		ExtKeyUsage:           []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
+		BasicConstraintsValid: true,
+	}
+
+	hosts := strings.Split(*host, ",")
+	for _, h := range hosts {
+		if ip := net.ParseIP(h); ip != nil {
+			template.IPAddresses = append(template.IPAddresses, ip)
+		} else {
+			// We use IDNA-encoded DNS names, otherwise the TLS library won't
+			// load the certificates.
+			ih, err := idna.ToASCII(h)
+			if err != nil {
+				log.Fatalf("host %q cannot be IDNA-encoded: %v", h, err)
+			}
+			template.DNSNames = append(template.DNSNames, ih)
+		}
+	}
+
+	if *isCA {
+		template.IsCA = true
+		template.KeyUsage |= x509.KeyUsageCertSign
+	}
+
+	derBytes, err := x509.CreateCertificate(rand.Reader, &template, &template, publicKey(priv), priv)
+	if err != nil {
+		log.Fatalf("Failed to create certificate: %s", err)
+	}
+
+	certOut, err := os.Create("fullchain.pem")
+	if err != nil {
+		log.Fatalf("failed to open fullchain.pem for writing: %s", err)
+	}
+	pem.Encode(certOut, &pem.Block{Type: "CERTIFICATE", Bytes: derBytes})
+	certOut.Close()
+
+	keyOut, err := os.OpenFile("privkey.pem", os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
+	if err != nil {
+		log.Fatalf("failed to open privkey.pem for writing: %s", err)
+		return
+	}
+	pem.Encode(keyOut, pemBlockForKey(priv))
+	keyOut.Close()
+}