[wpr-go] Use a dummy cert if no cert is recorded

web_page_replay_go/src/webpagereplay/legacyformatconvertor.go

Index: web_page_replay_go/src/webpagereplay/legacyformatconvertor.go
diff --git a/web_page_replay_go/src/webpagereplay/legacyformatconvertor.go b/web_page_replay_go/src/webpagereplay/legacyformatconvertor.go
index 5fe4fca959ed46ecbb9f6d6c443948a7731770c7..61f5b27a8d68a41bbaad8d30badd24ca5991bd33 100644
--- a/web_page_replay_go/src/webpagereplay/legacyformatconvertor.go
+++ b/web_page_replay_go/src/webpagereplay/legacyformatconvertor.go
@@ -10,14 +10,11 @@ package webpagereplay
 
 import (
 	"bytes"
-	"crypto"
-	"crypto/rand"
 	"crypto/tls"
 	"crypto/x509"
 	"encoding/base64"
 	"encoding/json"
 	"fmt"
-	"io"
 	"io/ioutil"
 	"net"
 	"net/http"
@@ -75,29 +72,6 @@ func (cfg *ConvertorConfig) Flags() []cli.Flag {
 	}
 }
 
-// Mints a dummy server cert to be used when the real server is not reachable.
-// This is used in the transition from the python wpr format to the new wprgo format where servers
-// from the old recordings (especially CDNs) have since become unreachable. crbug.com/730036
-func mintDummyCertificate(serverName string, rootCert *x509.Certificate, rootKey crypto.PrivateKey) ([]byte, string, error) {
-	template := rootCert
-	if ip := net.ParseIP(serverName); ip != nil {
-		template.IPAddresses = []net.IP{ip}
-	} else {
-		template.DNSNames = []string{serverName}
-	}
-	var buf [20]byte
-	if _, err := io.ReadFull(rand.Reader, buf[:]); err != nil {
-		return nil, "", fmt.Errorf("create cert failed: %v", err)
-	}
-	template.SerialNumber.SetBytes(buf[:])
-	template.Issuer = template.Subject
-	derBytes, err := x509.CreateCertificate(rand.Reader, template, template, template.PublicKey, rootKey)
-	if err != nil {
-		return nil, "", fmt.Errorf("create cert failed: %v", err)
-	}
-	return derBytes, "", err
-}
-
 func (r *ConvertorConfig) recordServerCert(scheme string, serverName string, archive *WritableArchive) error {
 	if scheme != "https" {
 		return nil
@@ -108,7 +82,7 @@ func (r *ConvertorConfig) recordServerCert(scheme string, serverName string, arc
 	}
 	derBytes, negotiatedProtocol, err = MintServerCert(serverName, r.x509Cert, r.tlsCert.PrivateKey)
 	if err != nil {
-		derBytes, negotiatedProtocol, err = mintDummyCertificate(serverName, r.x509Cert, r.tlsCert.PrivateKey)
+		derBytes, negotiatedProtocol, err = MintDummyCertificate(serverName, r.x509Cert, r.tlsCert.PrivateKey)
 		if err != nil {
 			return err
 		}