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c6b92ddda8
goupnp is an existing upnp client for go, which provides all the functionality we need, licensed under BSD-2-Clause, so we can copy it over and modify parts of it for our case. Specifically, we add contexts to all the methods so we can better handle timeouts, remove the dependency on large charsets, and (eventually) trim out extra components we don't need. Signed-off-by: julianknodt <julianknodt@gmail.com>
103 lines
2.9 KiB
Go
103 lines
2.9 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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)
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const (
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ssdpDiscover = `"ssdp:discover"`
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ntsAlive = `ssdp:alive`
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ntsByebye = `ssdp:byebye`
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ntsUpdate = `ssdp:update`
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ssdpUDP4Addr = "239.255.255.250:1900"
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ssdpSearchPort = 1900
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methodSearch = "M-SEARCH"
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methodNotify = "NOTIFY"
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// SSDPAll is a value for searchTarget that searches for all devices and services.
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SSDPAll = "ssdp:all"
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// UPNPRootDevice is a value for searchTarget that searches for all root devices.
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UPNPRootDevice = "upnp:rootdevice"
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)
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// HTTPUClient is the interface required to perform HTTP-over-UDP requests.
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type HTTPUClient interface {
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Do(
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req *http.Request,
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timeout time.Duration,
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numSends int,
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) ([]*http.Response, error)
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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(
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httpu HTTPUClient,
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searchTarget string,
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maxWaitSeconds int,
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numSends int,
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) ([]*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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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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isExactSearch := searchTarget != SSDPAll && searchTarget != UPNPRootDevice
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seenUSNs := make(map[string]bool)
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var responses []*http.Response
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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"); isExactSearch && st != searchTarget {
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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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// Empty/missing USN in search response - using location instead.
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location, err := response.Location()
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if err != nil {
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// No usable location in search response - discard.
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continue
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}
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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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