commit 46e612d2e9afd6e5dfa54c473ed17aeab49001af Author: David Fifield david@bamsoftware.com Date: Wed Dec 29 22:06:41 2021 -0700

Fix the locking around rt.rt.

sync.Once does not prevent other goroutines from accessing a variable that has not been defined yet. --- meek-client/utls.go | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/meek-client/utls.go b/meek-client/utls.go index 1f3effb..3bb5308 100644 --- a/meek-client/utls.go +++ b/meek-client/utls.go @@ -97,7 +97,7 @@ type UTLSRoundTripper struct { clientHelloID *utls.ClientHelloID config *utls.Config proxyDialer proxy.Dialer - rtOnce sync.Once + rtLock sync.Mutex rt http.RoundTripper

// Transport for HTTP requests, which don't use uTLS. @@ -114,12 +114,14 @@ func (rt *UTLSRoundTripper) RoundTrip(req *http.Request) (*http.Response, error) return nil, fmt.Errorf("unsupported URL scheme %q", req.URL.Scheme) }

- // On the first call, make an http.Transport or http2.Transport as - // appropriate. var err error - rt.rtOnce.Do(func() { + rt.rtLock.Lock() + if rt.rt == nil { + // On the first call, make an http.Transport or http2.Transport + // as appropriate. rt.rt, err = makeRoundTripper(req.URL, rt.clientHelloID, rt.config, rt.proxyDialer) - }) + } + rt.rtLock.Unlock() if err != nil { return nil, err }