status-go/vendor/github.com/koron/go-ssdp/search.go

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2019-06-09 07:24:20 +00:00
package ssdp
import (
"bufio"
"bytes"
"errors"
"fmt"
"net"
"net/http"
"regexp"
"strconv"
"time"
)
// Service is discovered service.
type Service struct {
// Type is a property of "ST"
Type string
// USN is a property of "USN"
USN string
// Location is a property of "LOCATION"
Location string
// Server is a property of "SERVER"
Server string
rawHeader http.Header
maxAge *int
}
var rxMaxAge = regexp.MustCompile(`\bmax-age\s*=\s*(\d+)\b`)
func extractMaxAge(s string, value int) int {
v := value
if m := rxMaxAge.FindStringSubmatch(s); m != nil {
i64, err := strconv.ParseInt(m[1], 10, 32)
if err == nil {
v = int(i64)
}
}
return v
}
// MaxAge extracts "max-age" value from "CACHE-CONTROL" property.
func (s *Service) MaxAge() int {
if s.maxAge == nil {
s.maxAge = new(int)
*s.maxAge = extractMaxAge(s.rawHeader.Get("CACHE-CONTROL"), -1)
}
return *s.maxAge
}
// Header returns all properties in response of search.
func (s *Service) Header() http.Header {
return s.rawHeader
}
const (
// All is a search type to search all services and devices.
All = "ssdp:all"
// RootDevice is a search type to search UPnP root devices.
RootDevice = "upnp:rootdevice"
)
// Search searchs services by SSDP.
func Search(searchType string, waitSec int, localAddr string) ([]Service, error) {
// dial multicast UDP packet.
conn, err := multicastListen(localAddr)
if err != nil {
return nil, err
}
defer conn.Close()
logf("search on %s", conn.LocalAddr().String())
// send request.
msg, err := buildSearch(ssdpAddrIPv4, searchType, waitSec)
if err != nil {
return nil, err
}
if _, err := conn.WriteTo(msg, ssdpAddrIPv4); err != nil {
return nil, err
}
// wait response.
var list []Service
h := func(a net.Addr, d []byte) error {
srv, err := parseService(a, d)
if err != nil {
logf("invalid search response from %s: %s", a.String(), err)
return nil
}
list = append(list, *srv)
logf("search response from %s: %s", a.String(), srv.USN)
return nil
}
d := time.Second * time.Duration(waitSec)
if err := conn.readPackets(d, h); err != nil {
return nil, err
}
return list, err
}
func buildSearch(raddr net.Addr, searchType string, waitSec int) ([]byte, error) {
b := new(bytes.Buffer)
// FIXME: error should be checked.
b.WriteString("M-SEARCH * HTTP/1.1\r\n")
fmt.Fprintf(b, "HOST: %s\r\n", raddr.String())
fmt.Fprintf(b, "MAN: %q\r\n", "ssdp:discover")
fmt.Fprintf(b, "MX: %d\r\n", waitSec)
fmt.Fprintf(b, "ST: %s\r\n", searchType)
b.WriteString("\r\n")
return b.Bytes(), nil
}
var (
errWithoutHTTPPrefix = errors.New("without HTTP prefix")
)
// FIXME: https://github.com/koron/go-ssdp/issues/10
var endOfHeader = []byte{'\r', '\n', '\r', '\n'}
func parseService(addr net.Addr, data []byte) (*Service, error) {
if !bytes.HasPrefix(data, []byte("HTTP")) {
return nil, errWithoutHTTPPrefix
}
// Complement newlines on tail of header for buggy SSDP responses.
if !bytes.HasSuffix(data, endOfHeader) {
// why we should't use append() for this purpose:
// https://play.golang.org/p/IM1pONW9lqm
data = bytes.Join([][]byte{data, endOfHeader}, nil)
}
resp, err := http.ReadResponse(bufio.NewReader(bytes.NewReader(data)), nil)
if err != nil {
return nil, err
}
defer resp.Body.Close()
return &Service{
Type: resp.Header.Get("ST"),
USN: resp.Header.Get("USN"),
Location: resp.Header.Get("LOCATION"),
Server: resp.Header.Get("SERVER"),
rawHeader: resp.Header,
}, nil
}