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// Copyright 2015 Matthew Holt and The Caddy Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package fastcgi
import (
"bytes"
"encoding/binary"
)
// streamWriter abstracts out the separation of a stream into discrete records.
// It only writes maxWrite bytes at a time.
type streamWriter struct {
c *client
h header
buf *bytes.Buffer
recType uint8
}
func (w *streamWriter) writeRecord(recType uint8, content []byte) (err error) {
w.h.init(recType, w.c.reqID, len(content))
w.buf.Write(pad[:8])
w.writeHeader()
w.buf.Write(content)
w.buf.Write(pad[:w.h.PaddingLength])
_, err = w.buf.WriteTo(w.c.rwc)
return err
}
func (w *streamWriter) writeBeginRequest(role uint16, flags uint8) error {
b := [8]byte{byte(role >> 8), byte(role), flags}
return w.writeRecord(BeginRequest, b[:])
}
func (w *streamWriter) Write(p []byte) (int, error) {
// init header
if w.buf.Len() < 8 {
w.buf.Write(pad[:8])
}
nn := 0
for len(p) > 0 {
n := len(p)
nl := maxWrite + 8 - w.buf.Len()
if n > nl {
n = nl
w.buf.Write(p[:n])
if err := w.Flush(); err != nil {
return nn, err
}
// reset headers
w.buf.Write(pad[:8])
} else {
w.buf.Write(p[:n])
}
nn += n
p = p[n:]
}
return nn, nil
}
func (w *streamWriter) endStream() error {
// send empty record to close the stream
return w.writeRecord(w.recType, nil)
}
func (w *streamWriter) writePairs(pairs map[string]string) error {
b := make([]byte, 8)
nn := 0
// init headers
w.buf.Write(b)
for k, v := range pairs {
m := 8 + len(k) + len(v)
if m > maxWrite {
// param data size exceed 65535 bytes"
vl := maxWrite - 8 - len(k)
v = v[:vl]
}
n := encodeSize(b, uint32(len(k)))
n += encodeSize(b[n:], uint32(len(v)))
m = n + len(k) + len(v)
if (nn + m) > maxWrite {
if err := w.Flush(); err != nil {
return err
}
// reset headers
w.buf.Write(b)
nn = 0
}
nn += m
w.buf.Write(b[:n])
w.buf.WriteString(k)
w.buf.WriteString(v)
}
return w.FlushStream()
}
func encodeSize(b []byte, size uint32) int {
if size > 127 {
size |= 1 << 31
binary.BigEndian.PutUint32(b, size)
return 4
}
b[0] = byte(size)
return 1
}
// writeHeader populate header wire data in buf, it abuses buffer.Bytes() modification
func (w *streamWriter) writeHeader() {
h := w.buf.Bytes()[:8]
h[0] = w.h.Version
h[1] = w.h.Type
binary.BigEndian.PutUint16(h[2:4], w.h.ID)
binary.BigEndian.PutUint16(h[4:6], w.h.ContentLength)
h[6] = w.h.PaddingLength
h[7] = w.h.Reserved
}
// Flush write buffer data to the underlying connection, it assumes header data is the first 8 bytes of buf
func (w *streamWriter) Flush() error {
w.h.init(w.recType, w.c.reqID, w.buf.Len()-8)
w.writeHeader()
w.buf.Write(pad[:w.h.PaddingLength])
_, err := w.buf.WriteTo(w.c.rwc)
return err
}
// FlushStream flush data then end current stream
func (w *streamWriter) FlushStream() error {
if err := w.Flush(); err != nil {
return err
}
return w.endStream()
}
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