net/http: enable Transfer-Encoding: identity without Content-Length for HTTP 1.1.

Use case is SSE recommended configuration: http://www.w3.org/TR/eventsource/#notes
Removes a TODO.

LGTM=bradfitz
R=golang-codereviews, bradfitz, tommi.virtanen
CC=golang-codereviews
https://golang.org/cl/100000044

1 files changed, 14 insertions, 7 deletions

diff --git a/src/net/http/server.go b/src/net/http/server.go
index 7ad0bcbc20..b5959f7321 100644
--- a/src/net/http/server.go
+++ b/src/net/http/server.go
@@ -839,13 +839,20 @@ func (cw *chunkWriter) writeHeader(p []byte) {
 	} else if hasCL {
 		delHeader("Transfer-Encoding")
 	} else if w.req.ProtoAtLeast(1, 1) {
-		// HTTP/1.1 or greater: use chunked transfer encoding
-		// to avoid closing the connection at EOF.
-		// TODO: this blows away any custom or stacked Transfer-Encoding they
-		// might have set.  Deal with that as need arises once we have a valid
-		// use case.
-		cw.chunking = true
-		setHeader.transferEncoding = "chunked"
+		// HTTP/1.1 or greater: Transfer-Encoding has been set to identity,  and no
+		// content-length has been provided. The connection must be closed after the
+		// reply is written, and no chunking is to be done. This is the setup
+		// recommended in the Server-Sent Events candidate recommendation 11,
+		// section 8.
+		if hasTE && te == "identity" {
+			cw.chunking = false
+			w.closeAfterReply = true
+		} else {
+			// HTTP/1.1 or greater: use chunked transfer encoding
+			// to avoid closing the connection at EOF.
+			cw.chunking = true
+			setHeader.transferEncoding = "chunked"
+		}
 	} else {
 		// HTTP version < 1.1: cannot do chunked transfer
 		// encoding and we don't know the Content-Length so