diff options
Diffstat (limited to 'src/net/http/server.go')
| -rw-r--r-- | src/net/http/server.go | 44 |
1 files changed, 34 insertions, 10 deletions
diff --git a/src/net/http/server.go b/src/net/http/server.go index d44b0fb256..bc3a4633da 100644 --- a/src/net/http/server.go +++ b/src/net/http/server.go @@ -98,8 +98,8 @@ type ResponseWriter interface { // Handlers can set HTTP trailers. // // Changing the header map after a call to WriteHeader (or - // Write) has no effect unless the modified headers are - // trailers. + // Write) has no effect unless the HTTP status code was of the + // 1xx class or the modified headers are trailers. // // There are two ways to set Trailers. The preferred way is to // predeclare in the headers which trailers you will later @@ -144,13 +144,18 @@ type ResponseWriter interface { // If WriteHeader is not called explicitly, the first call to Write // will trigger an implicit WriteHeader(http.StatusOK). // Thus explicit calls to WriteHeader are mainly used to - // send error codes. + // send error codes or 1xx informational responses. // // The provided code must be a valid HTTP 1xx-5xx status code. - // Only one header may be written. Go does not currently - // support sending user-defined 1xx informational headers, - // with the exception of 100-continue response header that the - // Server sends automatically when the Request.Body is read. + // Any number of 1xx headers may be written, followed by at most + // one 2xx-5xx header. 1xx headers are sent immediately, but 2xx-5xx + // headers may be buffered. Use the Flusher interface to send + // buffered data. The header map is cleared when 2xx-5xx headers are + // sent, but not with 1xx headers. + // + // The server will automatically send a 100 (Continue) header + // on the first read from the request body if the request has + // an "Expect: 100-continue" header. WriteHeader(statusCode int) } @@ -420,7 +425,7 @@ type response struct { req *Request // request for this response reqBody io.ReadCloser cancelCtx context.CancelFunc // when ServeHTTP exits - wroteHeader bool // reply header has been (logically) written + wroteHeader bool // a non-1xx header has been (logically) written wroteContinue bool // 100 Continue response was written wants10KeepAlive bool // HTTP/1.0 w/ Connection "keep-alive" wantsClose bool // HTTP request has Connection "close" @@ -1100,8 +1105,7 @@ func checkWriteHeaderCode(code int) { // Issue 22880: require valid WriteHeader status codes. // For now we only enforce that it's three digits. // In the future we might block things over 599 (600 and above aren't defined - // at https://httpwg.org/specs/rfc7231.html#status.codes) - // and we might block under 200 (once we have more mature 1xx support). + // at https://httpwg.org/specs/rfc7231.html#status.codes). // But for now any three digits. // // We used to send "HTTP/1.1 000 0" on the wire in responses but there's @@ -1144,6 +1148,26 @@ func (w *response) WriteHeader(code int) { return } checkWriteHeaderCode(code) + + // Handle informational headers + if code >= 100 && code <= 199 { + // Prevent a potential race with an automatically-sent 100 Continue triggered by Request.Body.Read() + if code == 100 && w.canWriteContinue.isSet() { + w.writeContinueMu.Lock() + w.canWriteContinue.setFalse() + w.writeContinueMu.Unlock() + } + + writeStatusLine(w.conn.bufw, w.req.ProtoAtLeast(1, 1), code, w.statusBuf[:]) + + // Per RFC 8297 we must not clear the current header map + w.handlerHeader.WriteSubset(w.conn.bufw, excludedHeadersNoBody) + w.conn.bufw.Write(crlf) + w.conn.bufw.Flush() + + return + } + w.wroteHeader = true w.status = code |