Some initial experimentation with SCPD reading.
This commit is contained in:
John Beisley
167
v2alpha/description/scpd/scpd.go
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167
v2alpha/description/scpd/scpd.go
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@@ -0,0 +1,167 @@
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// Package scpd contains data structures that represent an SCPD at a higher level than XML.
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package scpd
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import (
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"errors"
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"fmt"
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"sort"
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"github.com/huin/goupnp/v2alpha/description/xmlscpd"
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)
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var (
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BadDescriptionError = errors.New("bad XML description")
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UnsupportedDescriptionError = errors.New("unsupported XML description")
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)
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// SCPD is the top level service description.
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type SCPD struct {
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actionByName map[string]*Action
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variableByName map[string]*StateVariable
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}
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// FromXML creates an SCPD from XML data.
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//
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// It assumes that xmlDesc.Clean() has been called.
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func FromXML(xmlDesc *xmlscpd.SCPD) (*SCPD, error) {
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stateVariables := make(map[string]*StateVariable, len(xmlDesc.StateVariables))
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for _, xmlSV := range xmlDesc.StateVariables {
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sv, err := stateVariableFromXML(xmlSV)
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if err != nil {
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return nil, fmt.Errorf("processing state variable %q: %w", xmlSV.Name, err)
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}
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if _, exists := stateVariables[sv.name]; exists {
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return nil, fmt.Errorf("%w: multiple state variables with name %q",
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BadDescriptionError, sv.name)
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}
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stateVariables[sv.name] = sv
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}
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actions := make(map[string]*Action, len(xmlDesc.Actions))
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for _, xmlAction := range xmlDesc.Actions {
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action, err := actionFromXML(xmlAction)
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if err != nil {
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return nil, fmt.Errorf("processing action %q: %w", xmlAction.Name, err)
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}
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if _, exists := actions[action.name]; exists {
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return nil, fmt.Errorf("%w: multiple actions with name %q",
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BadDescriptionError, action.name)
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}
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actions[action.name] = action
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}
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return &SCPD{
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actionByName: actions,
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variableByName: stateVariables,
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}, nil
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}
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// ActionNames returns the ordered names of each action.
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func (scpd *SCPD) ActionNames() []string {
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names := make([]string, 0, len(scpd.actionByName))
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for name := range scpd.actionByName {
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names = append(names, name)
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}
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sort.Strings(names)
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return names
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}
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// Action returns an action with the given name.
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func (scpd *SCPD) Action(name string) *Action {
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return scpd.actionByName[name]
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}
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// Variable returns a state variable with the given name.
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func (scpd *SCPD) Variable(name string) *StateVariable {
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return scpd.variableByName[name]
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}
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// Action describes a single UPnP SOAP action.
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type Action struct {
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name string
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inArgs []*Argument
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outArgs []*Argument
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}
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// actionFromXML creates an Action from the given XML description.
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func actionFromXML(xmlAction *xmlscpd.Action) (*Action, error) {
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if xmlAction.Name == "" {
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return nil, fmt.Errorf("%w: empty action name", BadDescriptionError)
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}
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var inArgs []*Argument
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var outArgs []*Argument
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for _, xmlArg := range xmlAction.Arguments {
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arg, err := argumentFromXML(xmlArg)
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if err != nil {
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return nil, fmt.Errorf("processing argument %q: %w", xmlArg.Name, err)
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}
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switch xmlArg.Direction {
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case "in":
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inArgs = append(inArgs, arg)
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case "out":
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outArgs = append(outArgs, arg)
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default:
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return nil, fmt.Errorf("%w: argument %q has invalid direction %q",
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BadDescriptionError, xmlArg.Name, xmlArg.Direction)
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}
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}
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return &Action{
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name: xmlAction.Name,
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inArgs: inArgs,
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outArgs: outArgs,
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}, nil
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}
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// Argument description data.
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type Argument struct {
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name string
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relatedStateVariable string
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}
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// argumentFromXML creates an Argument from the XML description.
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func argumentFromXML(xmlArg *xmlscpd.Argument) (*Argument, error) {
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if xmlArg.Name == "" {
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return nil, fmt.Errorf("%w: empty argument name", BadDescriptionError)
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}
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if xmlArg.RelatedStateVariable == "" {
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return nil, fmt.Errorf("%w: empty related state variable", BadDescriptionError)
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}
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return &Argument{
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name: xmlArg.Name,
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relatedStateVariable: xmlArg.RelatedStateVariable,
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}, nil
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}
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func (arg *Argument) Name() string {
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return arg.name
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}
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func (arg *Argument) RelatedStateVariableName() string {
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return arg.relatedStateVariable
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}
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// StateVariable description data.
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type StateVariable struct {
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name string
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dataType string
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}
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func stateVariableFromXML(xmlSV *xmlscpd.StateVariable) (*StateVariable, error) {
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if xmlSV.Name == "" {
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return nil, fmt.Errorf("%w: empty state variable name", BadDescriptionError)
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}
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if xmlSV.DataType.Type != "" {
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return nil, fmt.Errorf("%w: unsupported data type %q",
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UnsupportedDescriptionError, xmlSV.DataType.Type)
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}
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return &StateVariable{
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name: xmlSV.Name,
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dataType: xmlSV.DataType.Name,
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}, nil
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}
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func (sv *StateVariable) Name() string {
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return sv.name
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}
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func (sv *StateVariable) DataTypeName() string {
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return sv.dataType
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}
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161
v2alpha/description/xmlscpd/xmlscpd.go
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161
v2alpha/description/xmlscpd/xmlscpd.go
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@@ -0,0 +1,161 @@
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// Package xmlscpd contains the XML data structures used in SCPD (Service Control Protocol Description).
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//
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// Described in section 2.5 of
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// https://openconnectivity.org/upnp-specs/UPnP-arch-DeviceArchitecture-v2.0-20200417.pdf.
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package xmlscpd
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import (
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"bytes"
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"encoding/xml"
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"fmt"
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"strings"
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)
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func cleanWhitespace(s *string) {
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*s = strings.TrimSpace(*s)
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}
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// SCPD is the top level XML service description.
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type SCPD struct {
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XMLName xml.Name `xml:"scpd"`
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ConfigId string `xml:"configId,attr"`
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SpecVersion SpecVersion `xml:"specVersion"`
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Actions []*Action `xml:"actionList>action"`
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StateVariables []*StateVariable `xml:"serviceStateTable>stateVariable"`
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}
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// Clean removes stray whitespace in the structure.
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//
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// It's common for stray whitespace to be present in SCPD documents, this method removes them
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// in-place.
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func (scpd *SCPD) Clean() {
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cleanWhitespace(&scpd.ConfigId)
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for i := range scpd.Actions {
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scpd.Actions[i].Clean()
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}
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for i := range scpd.StateVariables {
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scpd.StateVariables[i].Clean()
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}
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}
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// SpecVersion is part of a SCPD document, describes the version of the
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// specification that the data adheres to.
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type SpecVersion struct {
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Major int32 `xml:"major"`
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Minor int32 `xml:"minor"`
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}
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// Action XML description data.
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type Action struct {
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Name string `xml:"name"`
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Arguments []*Argument `xml:"argumentList>argument"`
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}
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// Clean removes stray whitespace in the structure.
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func (action *Action) Clean() {
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cleanWhitespace(&action.Name)
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for i := range action.Arguments {
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action.Arguments[i].Clean()
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}
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}
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// Argument XML data.
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type Argument struct {
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Name string `xml:"name"`
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Direction string `xml:"direction"` // in|out
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RelatedStateVariable string `xml:"relatedStateVariable"` // ?
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Retval string `xml:"retval"` // ?
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}
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// Clean removes stray whitespace in the structure.
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func (arg *Argument) Clean() {
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cleanWhitespace(&arg.Name)
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cleanWhitespace(&arg.Direction)
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cleanWhitespace(&arg.RelatedStateVariable)
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cleanWhitespace(&arg.Retval)
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}
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// StateVariable XML data.
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type StateVariable struct {
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Optional PresenceBool
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Name string `xml:"name"`
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SendEvents string `xml:"sendEvents,attr"` // yes|no
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Multicast string `xml:"multicast,attr"` // yes|no
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DataType DataType `xml:"dataType"`
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DefaultValue string `xml:"defaultValue"`
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AllowedValueRange *AllowedValueRange `xml:"allowedValueRange"`
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AllowedValues []string `xml:"allowedValueList>allowedValue"`
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}
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// Clean removes stray whitespace in the structure.
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func (v *StateVariable) Clean() {
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cleanWhitespace(&v.Name)
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cleanWhitespace(&v.SendEvents)
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cleanWhitespace(&v.Multicast)
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v.DataType.Clean()
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cleanWhitespace(&v.DefaultValue)
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if v.AllowedValueRange != nil {
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v.AllowedValueRange.Clean()
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}
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for i := range v.AllowedValues {
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cleanWhitespace(&v.AllowedValues[i])
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}
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}
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// AllowedValueRange XML data.
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type AllowedValueRange struct {
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Minimum string `xml:"minimum"`
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Maximum string `xml:"maximum"`
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Step string `xml:"step"`
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}
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// Clean removes stray whitespace in the structure.
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func (r *AllowedValueRange) Clean() {
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cleanWhitespace(&r.Minimum)
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cleanWhitespace(&r.Maximum)
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cleanWhitespace(&r.Step)
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}
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// DataType XML data.
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type DataType struct {
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Name string `xml:",chardata"`
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Type string `xml:"type,attr"`
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}
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// Clean removes stray whitespace in the structure.
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func (dt *DataType) Clean() {
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cleanWhitespace(&dt.Name)
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cleanWhitespace(&dt.Type)
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}
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// PresenceBool represents an empty XML element that is true if present.
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//
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// Is an error if it contains any attributes or contents.
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type PresenceBool bool
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func (pb *PresenceBool) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
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*pb = true
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if len(start.Attr) > 0 {
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return fmt.Errorf("unexpected attributes on element %s:%s",
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start.Name.Space, start.Name.Local)
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}
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for {
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tok, err := d.Token()
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if err != nil {
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return err
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}
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switch tok := tok.(type) {
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case xml.CharData:
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if len(bytes.TrimSpace([]byte(tok))) > 0 {
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return fmt.Errorf("unexpected char data on element %s:%s",
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start.Name.Space, start.Name.Local)
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}
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case xml.EndElement:
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return nil
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case xml.Comment:
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default:
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return fmt.Errorf("unexpected %T token on element %s:%s",
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tok, start.Name.Space, start.Name.Local)
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}
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}
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}
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