Revert "net/tlsdial: add memory-optimized TLS cert verification path for iOS"

This reverts commit 6fcbd4c4d4.

Decided to put it in tailscale/go's crypto/x509 instead.

net/tlsdial/tlsdial.go

@@ -8,8 +8,6 @@ package tlsdial
 
 import "crypto/tls"
 
-var platformModifyConf func(*tls.Config)
-
 // Config returns a tls.Config for dialing the given host.
 // If base is non-nil, it's cloned as the base config before
 // being configured and returned.
@@ -22,9 +20,5 @@ func Config(host string, base *tls.Config) *tls.Config {
 	}
 	conf.ServerName = host
 
-	if platformModifyConf != nil {
-		platformModifyConf(conf)
-	}
-
 	return conf
 }

net/tlsdial/verify_darwin_arm64.go

@@ -1,58 +0,0 @@
-// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// +build darwin,arm64,usex509fork
-
-package tlsdial
-
-import (
-	"crypto/tls"
-	"errors"
-	"time"
-
-	"crypto/x509"
-
-	x509fork "tailscale.com/tempfork/x509"
-)
-
-func init() {
-	platformModifyConf = useX509Fork
-}
-
-func useX509Fork(conf *tls.Config) {
-	// Modify conf to use our fork of crypto/x509 instead.
-
-	// This prevents crypto/tls from using the standard library's
-	// x509. We will then be responsible for the rest.
-	conf.InsecureSkipVerify = true
-
-	// Do what crypto/tls would've done for us:
-	conf.VerifyPeerCertificate = func(rawCerts [][]byte, _verifiedChains [][]*x509.Certificate) error {
-		if conf.ServerName == "" {
-			return errors.New("no tls.Config.ServerName set")
-		}
-		if len(rawCerts) == 0 {
-			// Shouldn't happen, but.
-			return errors.New("no rawCerts from server")
-		}
-		certs := make([]*x509fork.Certificate, len(rawCerts))
-		for i, asn1Data := range rawCerts {
-			cert, err := x509fork.ParseCertificate(asn1Data)
-			if err != nil {
-				return err
-			}
-			certs[i] = cert
-		}
-		opts := x509fork.VerifyOptions{
-			CurrentTime:   time.Now(),
-			DNSName:       conf.ServerName,
-			Intermediates: x509fork.NewCertPool(),
-		}
-		for _, cert := range certs[1:] {
-			opts.Intermediates.AddCert(cert)
-		}
-		_, err := certs[0].Verify(opts)
-		return err
-	}
-}