Fix data race condition in the Alt-Svc cache

imroc · imroc · commit 4a167cb3fc0d · 2025-08-19T10:03:37.000+08:00
Signed-off-by: roc &lt;roc@imroc.cc&gt;
diff --git a/transport.go b/transport.go
@@ -846,7 +846,9 @@ func (t *Transport) checkAltSvc(req *http.Request) (resp *http.Response, err err
 		return
 	}
 	addr := netutil.AuthorityKey(req.URL)
+	t.pendingAltSvcsMu.Lock()
 	pas, ok := t.pendingAltSvcs[addr]
+	t.pendingAltSvcsMu.Unlock()
 	if ok && pas.Transport != nil {
 		pas.Mu.Lock()
 		if pas.Transport != nil {
@@ -862,7 +864,9 @@ func (t *Transport) checkAltSvc(req *http.Request) (resp *http.Response, err err
 				}
 			} else {
 				t.altSvcJar.SetAltSvc(addr, pas.Entries[pas.CurrentIndex])
+				t.pendingAltSvcsMu.Lock()
 				delete(t.pendingAltSvcs, addr)
+				t.pendingAltSvcsMu.Unlock()
 			}
 		}
 		pas.Mu.Unlock()

Original file line number	Diff line number	Diff line change
`@@ -846,7 +846,9 @@ func (t Transport) checkAltSvc(req http.Request) (resp *http.Response, err err`
`846`	`846`	`return`
`847`	`847`	`}`
`848`	`848`	`addr := netutil.AuthorityKey(req.URL)`
	`849`	`+ t.pendingAltSvcsMu.Lock()`
`849`	`850`	`pas, ok := t.pendingAltSvcs[addr]`
	`851`	`+ t.pendingAltSvcsMu.Unlock()`
`850`	`852`	`if ok && pas.Transport != nil {`
`851`	`853`	`pas.Mu.Lock()`
`852`	`854`	`if pas.Transport != nil {`
`@@ -862,7 +864,9 @@ func (t Transport) checkAltSvc(req http.Request) (resp *http.Response, err err`
`862`	`864`	`}`
`863`	`865`	`} else {`
`864`	`866`	`t.altSvcJar.SetAltSvc(addr, pas.Entries[pas.CurrentIndex])`
	`867`	`+ t.pendingAltSvcsMu.Lock()`
`865`	`868`	`delete(t.pendingAltSvcs, addr)`
	`869`	`+ t.pendingAltSvcsMu.Unlock()`
`866`	`870`	`}`
`867`	`871`	`}`
`868`	`872`	`pas.Mu.Unlock()`