Fix race in writeFrame

nhooyr · nhooyr · commit 0ed9c744fa64 · 2019-06-07T18:26:28.000-04:00
diff --git a/websocket.go b/websocket.go
@@ -632,8 +632,6 @@ func (c *Conn) writeFrame(ctx context.Context, fin bool, opcode opcode, p []byte
 		}
 	}
 
-	headerBytes := writeHeader(c.writeHeaderBuf, h)
-
 	err := c.acquireLock(ctx, c.writeFrameLock)
 	if err != nil {
 		return 0, err
@@ -664,6 +662,7 @@ func (c *Conn) writeFrame(ctx context.Context, fin bool, opcode opcode, p []byte
 		return err
 	}
 
+	headerBytes := writeHeader(c.writeHeaderBuf, h)
 	_, err = c.bw.Write(headerBytes)
 	if err != nil {
 		return 0, writeErr(err)

Original file line number	Diff line number	Diff line change
`@@ -632,8 +632,6 @@ func (c *Conn) writeFrame(ctx context.Context, fin bool, opcode opcode, p []byte`
`632`	`632`	`}`
`633`	`633`	`}`
`634`	`634`
`635`		`- headerBytes := writeHeader(c.writeHeaderBuf, h)`
`636`		`-`
`637`	`635`	`err := c.acquireLock(ctx, c.writeFrameLock)`
`638`	`636`	`if err != nil {`
`639`	`637`	`return 0, err`
`@@ -664,6 +662,7 @@ func (c *Conn) writeFrame(ctx context.Context, fin bool, opcode opcode, p []byte`
`664`	`662`	`return err`
`665`	`663`	`}`
`666`	`664`
	`665`	`+ headerBytes := writeHeader(c.writeHeaderBuf, h)`
`667`	`666`	`_, err = c.bw.Write(headerBytes)`
`668`	`667`	`if err != nil {`
`669`	`668`	`return 0, writeErr(err)`