79 lines
2.4 KiB
Go
79 lines
2.4 KiB
Go
package ssdp
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import (
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"errors"
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"log"
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"net/http"
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"net/url"
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"strconv"
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"time"
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"github.com/huin/goupnp/httpu"
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)
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const (
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ssdpDiscover = `"ssdp:discover"`
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methodSearch = "M-SEARCH"
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ssdpUDP4Addr = "239.255.255.250:1900"
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)
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// SSDPRawSearch performs a fairly raw SSDP search request, and returns the
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// unique response(s) that it receives. Each response has the requested
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// searchTarget, a USN, and a valid location. maxWaitSeconds states how long to
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// wait for responses in seconds, and must be a minimum of 1 (the
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// implementation waits an additional 100ms for responses to arrive), 2 is a
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// reasonable value for this. numSends is the number of requests to send - 3 is
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// a reasonable value for this.
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func SSDPRawSearch(httpu *httpu.HTTPUClient, searchTarget string, maxWaitSeconds int, numSends int) ([]*http.Response, error) {
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if maxWaitSeconds < 1 {
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return nil, errors.New("ssdp: maxWaitSeconds must be >= 1")
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}
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seenUsns := make(map[string]bool)
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var responses []*http.Response
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req := http.Request{
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Method: methodSearch,
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// TODO: Support both IPv4 and IPv6.
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Host: ssdpUDP4Addr,
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URL: &url.URL{Opaque: "*"},
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Header: http.Header{
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// Putting headers in here avoids them being title-cased.
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// (The UPnP discovery protocol uses case-sensitive headers)
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"HOST": []string{ssdpUDP4Addr},
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"MX": []string{strconv.FormatInt(int64(maxWaitSeconds), 10)},
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"MAN": []string{ssdpDiscover},
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"ST": []string{searchTarget},
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},
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}
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allResponses, err := httpu.Do(&req, time.Duration(maxWaitSeconds)*time.Second+100*time.Millisecond, numSends)
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if err != nil {
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return nil, err
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}
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for _, response := range allResponses {
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if response.StatusCode != 200 {
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log.Printf("ssdp: got response status code %q in search response", response.Status)
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continue
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}
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if st := response.Header.Get("ST"); st != searchTarget {
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log.Printf("ssdp: got unexpected search target result %q", st)
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continue
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}
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location, err := response.Location()
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if err != nil {
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log.Printf("ssdp: no usable location in search response (discarding): %v", err)
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continue
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}
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usn := response.Header.Get("USN")
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if usn == "" {
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log.Printf("ssdp: empty/missing USN in search response (using location instead): %v", err)
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usn = location.String()
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}
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if _, alreadySeen := seenUsns[usn]; !alreadySeen {
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seenUsns[usn] = true
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responses = append(responses, response)
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}
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}
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return responses, nil
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}
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