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chunked.go
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chunked.go
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package main
import (
"bufio"
"fmt"
"io"
)
func min(a, b int) int {
if a < b {
return a
}
return b
}
type ChunkedReader struct {
r *bufio.Reader
chunkLen int // -1 means the beginning of the next chunk
}
func NewChunkedReader(r io.Reader) *ChunkedReader {
// TODO: avoid creating new bufio.Reader if r is already implements it
return &ChunkedReader{bufio.NewReader(r), -1}
}
func (r *ChunkedReader) readChunkLength() error {
b, err := r.r.ReadBytes('\n')
if err != nil {
return fmt.Errorf("Failed to read chunk length: %v", err)
}
blen := len(b)
if blen < 2 || b[blen-2] != '\r' || b[blen-1] != '\n' {
return fmt.Errorf("Failed to read CRLF")
}
length := int(0)
for _, v := range b[:blen-2] {
if v >= '0' && v <= '9' {
length = length*16 + int(v-'0')
} else if v >= 'a' && v <= 'f' {
length = length*16 + int(v-'a') + 10
} else if v >= 'A' && v <= 'F' {
length = length*16 + int(v-'a') + 10
} else {
return fmt.Errorf("Invalid chunk length: %s", string(b))
}
}
r.chunkLen = length
return nil
}
func (r *ChunkedReader) readCRLF() error {
b, err := r.r.ReadBytes('\n')
if err != nil {
return err
}
blen := len(b)
if blen != 2 || b[blen-2] != '\r' || b[blen-1] != '\n' {
return fmt.Errorf("Failed to read CRLF")
}
return nil
}
func (r *ChunkedReader) Read(b []byte) (int, error) {
if r.chunkLen < 0 {
if err := r.readChunkLength(); err != nil {
return 0, err
}
}
if r.chunkLen == 0 {
err := r.readCRLF()
return 0, err
}
n := min(r.chunkLen, len(b))
m, err := r.r.Read(b[:n])
r.chunkLen -= m
if r.chunkLen == 0 {
r.chunkLen = -1
err = r.readCRLF()
}
if err != nil {
return m, err
}
return m, nil
}
var crlf = []byte("\r\n")
var closeBytes = []byte("0\r\n\r\n")
type ChunkedWriter struct {
w io.Writer
}
func NewChunkedWriter(w io.Writer) *ChunkedWriter {
return &ChunkedWriter{w}
}
func (w *ChunkedWriter) writeChunkLength(n int) error {
b := make([]byte, 0, 8)
for n > 0 {
hex := n % 16
if hex >= 10 {
b = append(b, byte(hex-10)+'a')
} else {
b = append(b, byte(hex)+'0')
}
n = n / 16
}
// TODO: avoid reverse
blen := len(b)
for i := 0; i < blen/2; i++ {
x, y := b[i], b[blen-i-1]
b[i] = y
b[blen-i-1] = x
}
b = append(b, crlf...)
m, err := w.w.Write(b)
if m != blen+2 || err != nil {
return fmt.Errorf("Failed to write chunk length")
}
return nil
}
func (w *ChunkedWriter) Write(b []byte) (int, error) {
blen := len(b)
if err := w.writeChunkLength(blen); err != nil {
return 0, err
}
writeSoFar := 0
for writeSoFar < blen {
m, err := w.w.Write(b[writeSoFar:])
writeSoFar += m
if err != nil {
return writeSoFar, err
}
}
m, err := w.w.Write(crlf)
if m != 2 || err != nil {
return blen, fmt.Errorf("Failed to write CRLF")
}
return blen, nil
}
func (w *ChunkedWriter) Close() error {
n, err := w.w.Write(closeBytes)
if err != nil || n != len(closeBytes) {
return fmt.Errorf("Failed to write the last chunk")
}
return nil
}