/* NAME rtsp.go DESCRIPTION rtsp.go provides functionality for forming and sending RTSP requests for methods, DESCRIBE, OPTIONS, SETUP and PLAY, as described by the RTSP standards, see https://tools.ietf.org/html/rfc7826 AUTHORS Saxon A. Nelson-Milton <saxon@ausocean.org> LICENSE This is Copyright (C) 2019 the Australian Ocean Lab (AusOcean). It is free software: you can redistribute it and/or modify them under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. It is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License in gpl.txt. If not, see http://www.gnu.org/licenses. */ // Package rtsp provides an RTSP client implementation and methods for // communication with an RTSP server to request video. package rtsp import ( "bufio" "errors" "fmt" "io" "io/ioutil" "net/http" "net/url" "strconv" "strings" ) // Minimum response size to be considered valid in bytes. const minResponse = 12 var errInvalidResponse = errors.New("invalid response") // Request describes an RTSP request. type Request struct { Method string URL *url.URL Proto string ProtoMajor int ProtoMinor int Header http.Header ContentLength int Body io.ReadCloser } // NewRequest returns a pointer to a new Request. func NewRequest(method, cSeq string, u *url.URL, body io.ReadCloser) (*Request, error) { req := &Request{ Method: method, URL: u, Proto: "RTSP", ProtoMajor: 1, ProtoMinor: 0, Header: map[string][]string{"CSeq": []string{cSeq}}, Body: body, } return req, nil } // Write writes the request r to the given io.Writer w. func (r *Request) Write(w io.Writer) error { _, err := w.Write([]byte(r.String())) return err } // String returns a formatted string of the Request. func (r Request) String() string { var b strings.Builder fmt.Fprintf(&b, "%s %s %s/%d.%d\r\n", r.Method, r.URL.String(), r.Proto, r.ProtoMajor, r.ProtoMinor) for k, v := range r.Header { for _, v := range v { fmt.Fprintf(&b, "%s: %s\r\n", k, v) } } b.WriteString("\r\n") if r.Body != nil { s, _ := ioutil.ReadAll(r.Body) b.WriteString(string(s)) } return b.String() } // Response describes an RTSP response. type Response struct { Proto string ProtoMajor int ProtoMinor int StatusCode int ContentLength int Header http.Header Body io.ReadCloser } // String returns a formatted string of the Response. func (r Response) String() string { var b strings.Builder fmt.Fprintf(&b, "%s/%d.%d %d\n", r.Proto, r.ProtoMajor, r.ProtoMinor, r.StatusCode) for k, v := range r.Header { for _, v := range v { fmt.Fprintf(&b, "%s: %s", k, v) } } return b.String() } // ReadResponse will read the response of the RTSP request from the connection, // and return a pointer to a new Response. func ReadResponse(r io.Reader) (*Response, error) { resp := &Response{Header: make(map[string][]string)} scanner := bufio.NewScanner(r) // Read the first line. scanner.Scan() err := scanner.Err() if err != nil { return nil, err } s := scanner.Text() if len(s) < minResponse || !strings.HasPrefix(s, "RTSP/") { return nil, errInvalidResponse } resp.Proto = "RTSP" n, err := fmt.Sscanf(s[5:], "%d.%d %d", &resp.ProtoMajor, &resp.ProtoMinor, &resp.StatusCode) if err != nil || n != 3 { return nil, fmt.Errorf("could not Sscanf response, error: %w", err) } // Read headers. for scanner.Scan() { err = scanner.Err() if err != nil { return nil, err } parts := strings.SplitN(scanner.Text(), ":", 2) if len(parts) < 2 { break } resp.Header.Add(strings.TrimSpace(parts[0]), strings.TrimSpace(parts[1])) } // Get the content length from the header. resp.ContentLength, _ = strconv.Atoi(resp.Header.Get("Content-Length")) resp.Body = closer{r} return resp, nil } type closer struct { io.Reader } func (c closer) Close() error { if c.Reader == nil { return nil } defer func() { c.Reader = nil }() if r, ok := c.Reader.(io.ReadCloser); ok { return r.Close() } return nil }