initial commit

2025-09-26 19:21:20 +08:00 · 2020-01-20 10:15:24 +01:00
parent d96555515e
commit a604f8bd66
12 changed files with 758 additions and 1 deletions
--- a/.dockerignore
+++ b/.dockerignore
@@ -0,0 +1 @@
+.git
--- a/.travis.yml
+++ b/.travis.yml
@@ -0,0 +1,14 @@
+language: go
+
+go:
+- "1.12.x"
+- "1.13.x"
+
+env:
+- GO111MODULE=on
+
+before_install:
+- go mod download
+
+script:
+- make test-nodocker
--- a/45
+++ b/45
@@ -0,0 +1,45 @@
+
+.PHONY: $(shell ls)
+
+BASE_IMAGE = amd64/golang:1.13-alpine3.10
+
+help:
+	@echo "usage: make [action]"
+	@echo ""
+	@echo "available actions:"
+	@echo ""
+	@echo "  mod-tidy       run go mod tidy"
+	@echo "  format         format source files"
+	@echo "  test           run available tests"
+	@echo ""
+
+mod-tidy:
+	docker run --rm -it -v $(PWD):/s $(BASE_IMAGE) \
+	sh -c "apk add git && cd /s && go get && go mod tidy"
+
+format:
+	docker run --rm -it -v $(PWD):/s $(BASE_IMAGE) \
+	sh -c "cd /s && find . -type f -name '*.go' | xargs gofmt -l -w -s"
+
+define DOCKERFILE_TEST
+FROM $(BASE_IMAGE)
+RUN apk add --no-cache make git
+WORKDIR /s
+COPY go.mod go.sum ./
+RUN go mod download
+COPY . ./
+endef
+export DOCKERFILE_TEST
+
+test:
+	echo "$$DOCKERFILE_TEST" | docker build -q . -f - -t temp
+	docker run --rm -it \
+	--name temp \
+	temp \
+	make test-nodocker
+
+IMAGES = $(shell echo test-images/*/ | xargs -n1 basename)
+
+test-nodocker:
+	$(eval export CGO_ENABLED = 0)
+	go test -v .
--- a/README.md
+++ b/README.md
@@ -1,2 +1,10 @@
+
 # gortsplib
-RTSP primitives for the go programming language
+
+[![GoDoc](https://godoc.org/github.com/aler9/gortsplib?status.svg)](https://godoc.org/github.com/aler9/gortsplib)
+[![Go Report Card](https://goreportcard.com/badge/github.com/aler9/gortsplib)](https://goreportcard.com/report/github.com/aler9/gortsplib)
+[![Build Status](https://travis-ci.org/aler9/gortsplib.svg?branch=master)](https://travis-ci.org/aler9/gortsplib)
+
+RTSP primitives for the Go programming language.
+
+See [rtsp-simple-server](https://github.com/aler9/rtsp-simple-server) and [rtsp-simple-proxy](https://github.com/aler9/rtsp-simple-proxy) for examples on how to use this library.
--- a/conn.go
+++ b/conn.go
@@ -0,0 +1,90 @@
+package gortsplib
+
+import (
+	"encoding/binary"
+	"fmt"
+	"io"
+	"net"
+)
+
+type Conn struct {
+	c        net.Conn
+	writeBuf []byte
+}
+
+func NewConn(c net.Conn) *Conn {
+	return &Conn{
+		c:        c,
+		writeBuf: make([]byte, 2048),
+	}
+}
+
+func (c *Conn) Close() error {
+	return c.c.Close()
+}
+
+func (c *Conn) RemoteAddr() net.Addr {
+	return c.c.RemoteAddr()
+}
+
+func (c *Conn) ReadRequest() (*Request, error) {
+	return requestDecode(c.c)
+}
+
+func (c *Conn) WriteRequest(req *Request) error {
+	return requestEncode(c.c, req)
+}
+
+func (c *Conn) ReadResponse() (*Response, error) {
+	return responseDecode(c.c)
+}
+
+func (c *Conn) WriteResponse(res *Response) error {
+	return responseEncode(c.c, res)
+}
+
+func (c *Conn) ReadInterleavedFrame(frame []byte) (int, int, error) {
+	var header [4]byte
+	_, err := io.ReadFull(c.c, header[:])
+	if err != nil {
+		return 0, 0, err
+	}
+
+	// connection terminated
+	if header[0] == 0x54 {
+		return 0, 0, io.EOF
+	}
+
+	if header[0] != 0x24 {
+		return 0, 0, fmt.Errorf("wrong magic byte (0x%.2x)", header[0])
+	}
+
+	framelen := binary.BigEndian.Uint16(header[2:])
+	if framelen > 2048 {
+		return 0, 0, fmt.Errorf("frame length greater than 2048")
+	}
+
+	_, err = io.ReadFull(c.c, frame[:framelen])
+	if err != nil {
+		return 0, 0, err
+	}
+
+	return int(header[1]), int(framelen), nil
+}
+
+func (c *Conn) WriteInterleavedFrame(channel int, frame []byte) error {
+	c.writeBuf[0] = 0x24
+	c.writeBuf[1] = byte(channel)
+	binary.BigEndian.PutUint16(c.writeBuf[2:], uint16(len(frame)))
+	n := copy(c.writeBuf[4:], frame)
+
+	_, err := c.c.Write(c.writeBuf[:4+n])
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func (c *Conn) Read(buf []byte) (int, error) {
+	return c.c.Read(buf)
+}
--- a/go.mod
+++ b/go.mod
@@ -0,0 +1,5 @@
+module github.com/aler9/gortsplib
+
+go 1.13
+
+require github.com/stretchr/testify v1.4.0
--- a/go.sum
+++ b/go.sum
@@ -0,0 +1,11 @@
+github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.4.0 h1:2E4SXV/wtOkTonXsotYi4li6zVWxYlZuYNCXe9XRJyk=
+github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v2 v2.2.2 h1:ZCJp+EgiOT7lHqUV2J862kp8Qj64Jo6az82+3Td9dZw=
+gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
--- a/request.go
+++ b/request.go
@@ -0,0 +1,88 @@
+package gortsplib
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+)
+
+type Request struct {
+	Method  string
+	Url     string
+	Headers map[string]string
+	Content []byte
+}
+
+func requestDecode(r io.Reader) (*Request, error) {
+	rb := bufio.NewReader(r)
+
+	req := &Request{}
+
+	byts, err := readBytesLimited(rb, ' ', 255)
+	if err != nil {
+		return nil, err
+	}
+	req.Method = string(byts[:len(byts)-1])
+
+	if len(req.Method) == 0 {
+		return nil, fmt.Errorf("empty method")
+	}
+
+	byts, err = readBytesLimited(rb, ' ', 255)
+	if err != nil {
+		return nil, err
+	}
+	req.Url = string(byts[:len(byts)-1])
+
+	if len(req.Url) == 0 {
+		return nil, fmt.Errorf("empty path")
+	}
+
+	byts, err = readBytesLimited(rb, '\r', 255)
+	if err != nil {
+		return nil, err
+	}
+	proto := string(byts[:len(byts)-1])
+
+	if proto != _RTSP_PROTO {
+		return nil, fmt.Errorf("expected '%s', got '%s'", _RTSP_PROTO, proto)
+	}
+
+	err = readByteEqual(rb, '\n')
+	if err != nil {
+		return nil, err
+	}
+
+	req.Headers, err = readHeaders(rb)
+	if err != nil {
+		return nil, err
+	}
+
+	req.Content, err = readContent(rb, req.Headers)
+	if err != nil {
+		return nil, err
+	}
+
+	return req, nil
+}
+
+func requestEncode(w io.Writer, req *Request) error {
+	wb := bufio.NewWriter(w)
+
+	_, err := wb.Write([]byte(req.Method + " " + req.Url + " " + _RTSP_PROTO + "\r\n"))
+	if err != nil {
+		return err
+	}
+
+	err = writeHeaders(wb, req.Headers)
+	if err != nil {
+		return err
+	}
+
+	err = writeContent(wb, req.Content)
+	if err != nil {
+		return err
+	}
+
+	return wb.Flush()
+}
--- a/request_test.go
+++ b/request_test.go
@@ -0,0 +1,134 @@
+package gortsplib
+
+import (
+	"bytes"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+var casesRequest = []struct {
+	name string
+	byts []byte
+	req  *Request
+}{
+	{
+		"options",
+		[]byte("OPTIONS rtsp://example.com/media.mp4 RTSP/1.0\r\n" +
+			"CSeq: 1\r\n" +
+			"Proxy-Require: gzipped-messages\r\n" +
+			"Require: implicit-play\r\n" +
+			"\r\n"),
+		&Request{
+			Method: "OPTIONS",
+			Url:    "rtsp://example.com/media.mp4",
+			Headers: map[string]string{
+				"CSeq":          "1",
+				"Require":       "implicit-play",
+				"Proxy-Require": "gzipped-messages",
+			},
+		},
+	},
+	{
+		"describe",
+		[]byte("DESCRIBE rtsp://example.com/media.mp4 RTSP/1.0\r\n" +
+			"CSeq: 2\r\n" +
+			"\r\n"),
+		&Request{
+			Method: "DESCRIBE",
+			Url:    "rtsp://example.com/media.mp4",
+			Headers: map[string]string{
+				"CSeq": "2",
+			},
+		},
+	},
+	{
+		"announce",
+		[]byte("ANNOUNCE rtsp://example.com/media.mp4 RTSP/1.0\r\n" +
+			"CSeq: 7\r\n" +
+			"Content-Length: 306\r\n" +
+			"Content-Type: application/sdp\r\n" +
+			"Date: 23 Jan 1997 15:35:06 GMT\r\n" +
+			"Session: 12345678\r\n" +
+			"\r\n" +
+			"v=0\n" +
+			"o=mhandley 2890844526 2890845468 IN IP4 126.16.64.4\n" +
+			"s=SDP Seminar\n" +
+			"i=A Seminar on the session description protocol\n" +
+			"u=http://www.cs.ucl.ac.uk/staff/M.Handley/sdp.03.ps\n" +
+			"e=mjh@isi.edu (Mark Handley)\n" +
+			"c=IN IP4 224.2.17.12/127\n" +
+			"t=2873397496 2873404696\n" +
+			"a=recvonly\n" +
+			"m=audio 3456 RTP/AVP 0\n" +
+			"m=video 2232 RTP/AVP 31\n"),
+		&Request{
+			Method: "ANNOUNCE",
+			Url:    "rtsp://example.com/media.mp4",
+			Headers: map[string]string{
+				"CSeq":           "7",
+				"Date":           "23 Jan 1997 15:35:06 GMT",
+				"Session":        "12345678",
+				"Content-Type":   "application/sdp",
+				"Content-Length": "306",
+			},
+			Content: []byte("v=0\n" +
+				"o=mhandley 2890844526 2890845468 IN IP4 126.16.64.4\n" +
+				"s=SDP Seminar\n" +
+				"i=A Seminar on the session description protocol\n" +
+				"u=http://www.cs.ucl.ac.uk/staff/M.Handley/sdp.03.ps\n" +
+				"e=mjh@isi.edu (Mark Handley)\n" +
+				"c=IN IP4 224.2.17.12/127\n" +
+				"t=2873397496 2873404696\n" +
+				"a=recvonly\n" +
+				"m=audio 3456 RTP/AVP 0\n" +
+				"m=video 2232 RTP/AVP 31\n",
+			),
+		},
+	},
+	{
+		"get_parameter",
+		[]byte("GET_PARAMETER rtsp://example.com/media.mp4 RTSP/1.0\r\n" +
+			"CSeq: 9\r\n" +
+			"Content-Length: 24\r\n" +
+			"Content-Type: text/parameters\r\n" +
+			"Session: 12345678\r\n" +
+			"\r\n" +
+			"packets_received\n" +
+			"jitter\n"),
+		&Request{
+			Method: "GET_PARAMETER",
+			Url:    "rtsp://example.com/media.mp4",
+			Headers: map[string]string{
+				"CSeq":           "9",
+				"Content-Type":   "text/parameters",
+				"Session":        "12345678",
+				"Content-Length": "24",
+			},
+			Content: []byte("packets_received\n" +
+				"jitter\n",
+			),
+		},
+	},
+}
+
+func TestRequestDecode(t *testing.T) {
+	for _, c := range casesRequest {
+		t.Run(c.name, func(t *testing.T) {
+			req, err := requestDecode(bytes.NewBuffer(c.byts))
+			require.NoError(t, err)
+			require.Equal(t, c.req, req)
+		})
+	}
+}
+
+func TestRequestEncode(t *testing.T) {
+	for _, c := range casesRequest {
+		t.Run(c.name, func(t *testing.T) {
+			var buf bytes.Buffer
+			err := requestEncode(&buf, c.req)
+			require.NoError(t, err)
+			require.Equal(t, c.byts, buf.Bytes())
+		})
+	}
+}
--- a/response.go
+++ b/response.go
@@ -0,0 +1,95 @@
+package gortsplib
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"strconv"
+)
+
+type Response struct {
+	StatusCode int
+	Status     string
+	Headers    map[string]string
+	Content    []byte
+}
+
+func responseDecode(r io.Reader) (*Response, error) {
+	rb := bufio.NewReader(r)
+
+	res := &Response{}
+
+	byts, err := readBytesLimited(rb, ' ', 255)
+	if err != nil {
+		return nil, err
+	}
+	proto := string(byts[:len(byts)-1])
+
+	if proto != _RTSP_PROTO {
+		return nil, fmt.Errorf("expected '%s', got '%s'", _RTSP_PROTO, proto)
+	}
+
+	byts, err = readBytesLimited(rb, ' ', 4)
+	if err != nil {
+		return nil, err
+	}
+	statusCodeStr := string(byts[:len(byts)-1])
+
+	statusCode64, err := strconv.ParseInt(statusCodeStr, 10, 32)
+	res.StatusCode = int(statusCode64)
+	if err != nil {
+		return nil, fmt.Errorf("unable to parse status code")
+	}
+
+	byts, err = readBytesLimited(rb, '\r', 255)
+	if err != nil {
+		return nil, err
+	}
+	res.Status = string(byts[:len(byts)-1])
+
+	if len(res.Status) == 0 {
+		return nil, fmt.Errorf("empty status")
+	}
+
+	err = readByteEqual(rb, '\n')
+	if err != nil {
+		return nil, err
+	}
+
+	res.Headers, err = readHeaders(rb)
+	if err != nil {
+		return nil, err
+	}
+
+	res.Content, err = readContent(rb, res.Headers)
+	if err != nil {
+		return nil, err
+	}
+
+	return res, nil
+}
+
+func responseEncode(w io.Writer, res *Response) error {
+	wb := bufio.NewWriter(w)
+
+	_, err := wb.Write([]byte(_RTSP_PROTO + " " + strconv.FormatInt(int64(res.StatusCode), 10) + " " + res.Status + "\r\n"))
+	if err != nil {
+		return err
+	}
+
+	if len(res.Content) != 0 {
+		res.Headers["Content-Length"] = strconv.FormatInt(int64(len(res.Content)), 10)
+	}
+
+	err = writeHeaders(wb, res.Headers)
+	if err != nil {
+		return err
+	}
+
+	err = writeContent(wb, res.Content)
+	if err != nil {
+		return err
+	}
+
+	return wb.Flush()
+}
--- a/response_test.go
+++ b/response_test.go
@@ -0,0 +1,105 @@
+package gortsplib
+
+import (
+	"bytes"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+var casesResponse = []struct {
+	name string
+	byts []byte
+	res  *Response
+}{
+	{
+		"ok",
+		[]byte("RTSP/1.0 200 OK\r\n" +
+			"CSeq: 1\r\n" +
+			"Public: DESCRIBE, SETUP, TEARDOWN, PLAY, PAUSE\r\n" +
+			"\r\n",
+		),
+		&Response{
+			StatusCode: 200,
+			Status:     "OK",
+			Headers: map[string]string{
+				"CSeq":   "1",
+				"Public": "DESCRIBE, SETUP, TEARDOWN, PLAY, PAUSE",
+			},
+		},
+	},
+	{
+		"ok with content",
+		[]byte("RTSP/1.0 200 OK\r\n" +
+			"CSeq: 2\r\n" +
+			"Content-Base: rtsp://example.com/media.mp4\r\n" +
+			"Content-Length: 444\r\n" +
+			"Content-Type: application/sdp\r\n" +
+			"\r\n" +
+			"m=video 0 RTP/AVP 96\n" +
+			"a=control:streamid=0\n" +
+			"a=range:npt=0-7.741000\n" +
+			"a=length:npt=7.741000\n" +
+			"a=rtpmap:96 MP4V-ES/5544\n" +
+			"a=mimetype:string;\"video/MP4V-ES\"\n" +
+			"a=AvgBitRate:integer;304018\n" +
+			"a=StreamName:string;\"hinted video track\"\n" +
+			"m=audio 0 RTP/AVP 97\n" +
+			"a=control:streamid=1\n" +
+			"a=range:npt=0-7.712000\n" +
+			"a=length:npt=7.712000\n" +
+			"a=rtpmap:97 mpeg4-generic/32000/2\n" +
+			"a=mimetype:string;\"audio/mpeg4-generic\"\n" +
+			"a=AvgBitRate:integer;65790\n" +
+			"a=StreamName:string;\"hinted audio track\"\n",
+		),
+		&Response{
+			StatusCode: 200,
+			Status:     "OK",
+			Headers: map[string]string{
+				"Content-Base":   "rtsp://example.com/media.mp4",
+				"Content-Length": "444",
+				"Content-Type":   "application/sdp",
+				"CSeq":           "2",
+			},
+			Content: []byte("m=video 0 RTP/AVP 96\n" +
+				"a=control:streamid=0\n" +
+				"a=range:npt=0-7.741000\n" +
+				"a=length:npt=7.741000\n" +
+				"a=rtpmap:96 MP4V-ES/5544\n" +
+				"a=mimetype:string;\"video/MP4V-ES\"\n" +
+				"a=AvgBitRate:integer;304018\n" +
+				"a=StreamName:string;\"hinted video track\"\n" +
+				"m=audio 0 RTP/AVP 97\n" +
+				"a=control:streamid=1\n" +
+				"a=range:npt=0-7.712000\n" +
+				"a=length:npt=7.712000\n" +
+				"a=rtpmap:97 mpeg4-generic/32000/2\n" +
+				"a=mimetype:string;\"audio/mpeg4-generic\"\n" +
+				"a=AvgBitRate:integer;65790\n" +
+				"a=StreamName:string;\"hinted audio track\"\n",
+			),
+		},
+	},
+}
+
+func TestResponseDecode(t *testing.T) {
+	for _, c := range casesResponse {
+		t.Run(c.name, func(t *testing.T) {
+			res, err := responseDecode(bytes.NewBuffer(c.byts))
+			require.NoError(t, err)
+			require.Equal(t, c.res, res)
+		})
+	}
+}
+
+func TestResponseEncode(t *testing.T) {
+	for _, c := range casesResponse {
+		t.Run(c.name, func(t *testing.T) {
+			var buf bytes.Buffer
+			err := responseEncode(&buf, c.res)
+			require.NoError(t, err)
+			require.Equal(t, c.byts, buf.Bytes())
+		})
+	}
+}
--- a/utils.go
+++ b/utils.go
@@ -0,0 +1,161 @@
+package gortsplib
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"sort"
+	"strconv"
+)
+
+const (
+	_RTSP_PROTO              = "RTSP/1.0"
+	_MAX_HEADER_COUNT        = 255
+	_MAX_HEADER_KEY_LENGTH   = 255
+	_MAX_HEADER_VALUE_LENGTH = 255
+	_MAX_CONTENT_LENGTH      = 4096
+)
+
+func readBytesLimited(rb *bufio.Reader, delim byte, n int) ([]byte, error) {
+	for i := 1; i <= n; i++ {
+		byts, err := rb.Peek(i)
+		if err != nil {
+			return nil, err
+		}
+
+		if byts[len(byts)-1] == delim {
+			rb.Discard(len(byts))
+			return byts, nil
+		}
+	}
+	return nil, fmt.Errorf("buffer length exceeds %d", n)
+}
+
+func readByteEqual(rb *bufio.Reader, cmp byte) error {
+	byt, err := rb.ReadByte()
+	if err != nil {
+		return err
+	}
+
+	if byt != cmp {
+		return fmt.Errorf("expected '%c', got '%c'", cmp, byt)
+	}
+
+	return nil
+}
+
+func readHeaders(rb *bufio.Reader) (map[string]string, error) {
+	ret := make(map[string]string)
+
+	for {
+		byt, err := rb.ReadByte()
+		if err != nil {
+			return nil, err
+		}
+
+		if byt == '\r' {
+			err := readByteEqual(rb, '\n')
+			if err != nil {
+				return nil, err
+			}
+
+			break
+		}
+
+		if len(ret) >= _MAX_HEADER_COUNT {
+			return nil, fmt.Errorf("headers count exceeds %d", _MAX_HEADER_COUNT)
+		}
+
+		key := string([]byte{byt})
+		byts, err := readBytesLimited(rb, ':', _MAX_HEADER_KEY_LENGTH-1)
+		if err != nil {
+			return nil, err
+		}
+		key += string(byts[:len(byts)-1])
+
+		err = readByteEqual(rb, ' ')
+		if err != nil {
+			return nil, err
+		}
+
+		byts, err = readBytesLimited(rb, '\r', _MAX_HEADER_VALUE_LENGTH)
+		if err != nil {
+			return nil, err
+		}
+		val := string(byts[:len(byts)-1])
+
+		if len(val) == 0 {
+			return nil, fmt.Errorf("empty header value")
+		}
+
+		err = readByteEqual(rb, '\n')
+		if err != nil {
+			return nil, err
+		}
+
+		ret[key] = val
+	}
+
+	return ret, nil
+}
+
+func writeHeaders(wb *bufio.Writer, headers map[string]string) error {
+	// sort headers by key
+	// in order to obtain deterministic results
+	var keys []string
+	for key := range headers {
+		keys = append(keys, key)
+	}
+	sort.Strings(keys)
+
+	for _, key := range keys {
+		_, err := wb.Write([]byte(key + ": " + headers[key] + "\r\n"))
+		if err != nil {
+			return err
+		}
+	}
+
+	_, err := wb.Write([]byte("\r\n"))
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func readContent(rb *bufio.Reader, headers map[string]string) ([]byte, error) {
+	cls, ok := headers["Content-Length"]
+	if !ok {
+		return nil, nil
+	}
+
+	cl, err := strconv.ParseInt(cls, 10, 64)
+	if err != nil {
+		return nil, fmt.Errorf("invalid Content-Length")
+	}
+
+	if cl > _MAX_CONTENT_LENGTH {
+		return nil, fmt.Errorf("Content-Length exceeds %d", _MAX_CONTENT_LENGTH)
+	}
+
+	ret := make([]byte, cl)
+	n, err := io.ReadFull(rb, ret)
+	if err != nil && n != len(ret) {
+		return nil, err
+	}
+
+	return ret, nil
+}
+
+func writeContent(wb *bufio.Writer, content []byte) error {
+	if len(content) == 0 {
+		return nil
+	}
+
+	_, err := wb.Write(content)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}