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http: reply to Expect 100-continue requests automatically

This CL replaces my earlier https://golang.org/cl/1640044/show
in which Continue handling was explicit.  Instead, this CL makes
it automatic.  Reading from Body() is an implicit acknowledgement
that the request headers were fine and the body is wanted.  In that
case, the 100 Continue response is written automatically when the
request continues the "Expect: 100-continue" header.

R=rsc, adg
CC=golang-dev
https://golang.org/cl/1610042
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bradfitz authored and rsc committed Jun 16, 2010
1 parent 93ea2ae commit 743f818218c92822ee56d35e816d86a2205ff17a
Showing with 35 additions and 0 deletions.
  1. +5 −0 src/pkg/http/request.go
  2. +30 −0 src/pkg/http/server.go
@@ -635,3 +635,8 @@ func (r *Request) FormValue(key string) string {
}
return ""
}

func (r *Request) expectsContinue() bool {
expectation, ok := r.Header["Expect"]
return ok && strings.ToLower(expectation) == "100-continue"
}
@@ -56,6 +56,7 @@ type Conn struct {
closeAfterReply bool // close connection after this reply
chunking bool // using chunked transfer encoding for reply body
wroteHeader bool // reply header has been written
wroteContinue bool // 100 Continue response was written
header map[string]string // reply header parameters
written int64 // number of bytes written in body
status int // status code passed to WriteHeader
@@ -75,6 +76,28 @@ func newConn(rwc net.Conn, handler Handler) (c *Conn, err os.Error) {
return c, nil
}

// wrapper around io.ReaderCloser which on first read, sends an
// HTTP/1.1 100 Continue header
type expectContinueReader struct {
conn *Conn
readCloser io.ReadCloser
}

func (ecr *expectContinueReader) Read(p []byte) (n int, err os.Error) {
if !ecr.conn.wroteContinue && !ecr.conn.hijacked {
ecr.conn.wroteContinue = true
if ecr.conn.Req.ProtoAtLeast(1, 1) {
io.WriteString(ecr.conn.buf, "HTTP/1.1 100 Continue\r\n\r\n")
ecr.conn.buf.Flush()
}
}
return ecr.readCloser.Read(p)
}

func (ecr *expectContinueReader) Close() os.Error {
return ecr.readCloser.Close()
}

// Read next request from connection.
func (c *Conn) readRequest() (req *Request, err os.Error) {
if c.hijacked {
@@ -87,8 +110,15 @@ func (c *Conn) readRequest() (req *Request, err os.Error) {
// Reset per-request connection state.
c.header = make(map[string]string)
c.wroteHeader = false
c.wroteContinue = false
c.Req = req

// Expect 100 Continue support
if req.expectsContinue() {
// Wrap the Body reader with one that replies on the connection
req.Body = &expectContinueReader{readCloser: req.Body, conn: c}
}

// Default output is HTML encoded in UTF-8.
c.SetHeader("Content-Type", "text/html; charset=utf-8")

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