goupnp/goupnp.go

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// goupnp is an implementation of a client for various UPnP services.
//
// For most uses, it is recommended to use the code-generated packages under
// github.com/huin/goupnp/dcps. Example use is shown at
// http://godoc.org/github.com/huin/goupnp/example
//
// A commonly used client is internetgateway1.WANPPPConnection1:
// http://godoc.org/github.com/huin/goupnp/dcps/internetgateway1#WANPPPConnection1
//
// Currently only a couple of schemas have code generated for them from the
// UPnP example XML specifications. Not all methods will work on these clients,
// because the generated stubs contain the full set of specified methods from
// the XML specifications, and the discovered services will likely support a
// subset of those methods.
package goupnp
import (
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"context"
"encoding/xml"
"fmt"
"io"
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"net"
"net/http"
"net/url"
"time"
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"git.cyrilix.bzh/cyrilix/goupnp/httpu"
"git.cyrilix.bzh/cyrilix/goupnp/ssdp"
)
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// ContextError is an error that wraps an error with some context information.
type ContextError struct {
Context string
Err error
}
func ctxError(err error, msg string) ContextError {
return ContextError{
Context: msg,
Err: err,
}
}
func ctxErrorf(err error, msg string, args ...interface{}) ContextError {
return ContextError{
Context: fmt.Sprintf(msg, args...),
Err: err,
}
}
func (err ContextError) Error() string {
return fmt.Sprintf("%s: %v", err.Context, err.Err)
}
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// MaybeRootDevice contains either a RootDevice or an error.
type MaybeRootDevice struct {
// Identifier of the device. Note that this in combination with Location
// uniquely identifies a result from DiscoverDevices.
USN string
// Set iff Err == nil.
Root *RootDevice
// The location the device was discovered at. This can be used with
// DeviceByURL, assuming the device is still present. A location represents
// the discovery of a device, regardless of if there was an error probing it.
Location *url.URL
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// The address from which the device was discovered (if known - otherwise nil).
LocalAddr net.IP
// Any error encountered probing a discovered device.
Err error
}
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// DiscoverDevicesCtx attempts to find targets of the given type. This is
// typically the entry-point for this package. searchTarget is typically a URN
// in the form "urn:schemas-upnp-org:device:..." or
// "urn:schemas-upnp-org:service:...". A single error is returned for errors
// while attempting to send the query. An error or RootDevice is returned for
// each discovered RootDevice.
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func DiscoverDevicesCtx(ctx context.Context, searchTarget string) ([]MaybeRootDevice, error) {
hc, hcCleanup, err := httpuClient()
if err != nil {
return nil, err
}
defer hcCleanup()
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responses, err := ssdp.SSDPRawSearchCtx(ctx, hc, string(searchTarget), 2, 3)
if err != nil {
return nil, err
}
results := make([]MaybeRootDevice, len(responses))
for i, response := range responses {
maybe := &results[i]
maybe.USN = response.Header.Get("USN")
loc, err := response.Location()
if err != nil {
maybe.Err = ContextError{"unexpected bad location from search", err}
continue
}
maybe.Location = loc
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if root, err := DeviceByURLCtx(ctx, loc); err != nil {
maybe.Err = err
} else {
maybe.Root = root
}
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if i := response.Header.Get(httpu.LocalAddressHeader); len(i) > 0 {
maybe.LocalAddr = net.ParseIP(i)
}
}
return results, nil
}
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// DiscoverDevices is the legacy version of DiscoverDevicesCtx, but uses
// context.Background() as the context.
func DiscoverDevices(searchTarget string) ([]MaybeRootDevice, error) {
return DiscoverDevicesCtx(context.Background(), searchTarget)
}
func DeviceByURLCtx(ctx context.Context, loc *url.URL) (*RootDevice, error) {
locStr := loc.String()
root := new(RootDevice)
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if err := requestXml(ctx, locStr, DeviceXMLNamespace, root); err != nil {
return nil, ContextError{fmt.Sprintf("error requesting root device details from %q", locStr), err}
}
var urlBaseStr string
if root.URLBaseStr != "" {
urlBaseStr = root.URLBaseStr
} else {
urlBaseStr = locStr
}
urlBase, err := url.Parse(urlBaseStr)
if err != nil {
return nil, ContextError{fmt.Sprintf("error parsing location URL %q", locStr), err}
}
root.SetURLBase(urlBase)
return root, nil
}
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func DeviceByURL(loc *url.URL) (*RootDevice, error) {
return DeviceByURLCtx(context.Background(), loc)
}
// CharsetReaderDefault specifies the charset reader used while decoding the output
// from a UPnP server. It can be modified in an init function to allow for non-utf8 encodings,
// but should not be changed after requesting clients.
var CharsetReaderDefault func(charset string, input io.Reader) (io.Reader, error)
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func requestXml(ctx context.Context, url string, defaultSpace string, doc interface{}) error {
ctx, cancel := context.WithTimeout(ctx, 3*time.Second)
defer cancel()
req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
if err != nil {
return err
}
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resp, err := http.DefaultClient.Do(req)
if err != nil {
return err
}
defer resp.Body.Close()
if resp.StatusCode != 200 {
return fmt.Errorf("goupnp: got response status %s from %q",
resp.Status, url)
}
decoder := xml.NewDecoder(resp.Body)
decoder.DefaultSpace = defaultSpace
decoder.CharsetReader = CharsetReaderDefault
return decoder.Decode(doc)
}