152 lines
4.3 KiB
Go
152 lines
4.3 KiB
Go
// Package envelope is responsible for encoding and decoding SOAP envelopes.
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package envelope
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import (
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"encoding/xml"
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"errors"
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"fmt"
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"io"
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)
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// ErrFault can be used as a target with errors.Is.
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var ErrFault error = errors.New("xml fault")
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// FaultDetail carries XML-encoded application-specific Fault details.
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type FaultDetail struct {
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Raw []byte `xml:",innerxml"`
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}
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// Fault implements error, and contains SOAP fault information.
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type Fault struct {
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Code string `xml:"faultcode"`
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String string `xml:"faultstring"`
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Actor string `xml:"faultactor"`
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Detail FaultDetail `xml:"detail"`
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}
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func (fe *Fault) Error() string {
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return fmt.Sprintf("SOAP fault code=%s: %s", fe.Code, fe.String)
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}
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func (fe *Fault) Is(target error) bool {
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return target == ErrFault
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}
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// Action wraps a SOAP action to be read or written as part of a SOAP envelope.
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type Action struct {
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// XMLName specifies the XML element namespace (URI) and name. Together
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// these identify the SOAP action.
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XMLName xml.Name
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// Args is an arbitrary struct containing fields for encoding or decoding
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// arguments. See https://pkg.go.dev/encoding/xml@go1.17.1#Marshal and
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// https://pkg.go.dev/encoding/xml@go1.17.1#Unmarshal for details on
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// annotating fields in the structure.
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Args any
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}
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// NewSendAction creates a SOAP action for receiving arguments.
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func NewRecvAction(args any) *Action {
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return &Action{Args: args}
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}
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// NewSendAction creates a SOAP action for sending with the given namespace URL,
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// action name, and arguments.
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func NewSendAction(serviceType, actionName string, args any) *Action {
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return &Action{
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XMLName: xml.Name{Space: serviceType, Local: actionName},
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Args: args,
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}
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}
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var _ xml.Marshaler = &Action{}
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// MarshalXML implements `xml.Marshaller`.
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//
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// This is an implementation detail that allows packing elements inside the
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// action element from the struct in `a.Args`.
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func (a *Action) MarshalXML(e *xml.Encoder, start xml.StartElement) error {
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// Hardcodes the XML namespace. See comment in Write() for context.
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return e.EncodeElement(a.Args, xml.StartElement{
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Name: xml.Name{Space: "", Local: "u:" + a.XMLName.Local},
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Attr: []xml.Attr{{
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Name: xml.Name{Space: "", Local: "xmlns:u"},
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Value: a.XMLName.Space,
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}},
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})
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}
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var _ xml.Unmarshaler = &Action{}
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// UnmarshalXML implements `xml.Unmarshaller`.
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//
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// This is an implementation detail that allows unpacking elements inside the
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// action element into the struct in `a.Args`.
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func (a *Action) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
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a.XMLName = start.Name
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return d.DecodeElement(a.Args, &start)
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}
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// Various "constant" bytes used in the written envelope.
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var (
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envOpen = []byte(xml.Header + `<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/" s:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"><s:Body>`)
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envClose = []byte(`</s:Body></s:Envelope>`)
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)
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// Write marshals a SOAP envelope to the writer. Errors can be from the writer
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// or XML encoding.
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func Write(w io.Writer, action *Action) error {
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// Experiments with one router have shown that it 500s for requests where
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// the outer default xmlns is set to the SOAP namespace, and then
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// reassigning the default namespace within that to the service namespace.
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// Most of the code in this function is hand-coding the outer XML to
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// workaround this.
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// Resolving https://github.com/golang/go/issues/9519 might remove the need
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// for this workaround.
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_, err := w.Write(envOpen)
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if err != nil {
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return err
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}
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enc := xml.NewEncoder(w)
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err = enc.Encode(action)
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if err != nil {
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return err
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}
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err = enc.Flush()
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_, err = w.Write(envClose)
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return err
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}
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// Read unmarshals a SOAP envelope from the reader. Errors can either be from
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// the reader, XML decoding, or a *Fault.
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func Read(r io.Reader, action *Action) error {
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env := envelope{
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Body: body{
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Action: action,
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},
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}
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dec := xml.NewDecoder(r)
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err := dec.Decode(&env)
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if err != nil {
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return err
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}
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if env.Body.Fault != nil {
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return env.Body.Fault
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}
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return nil
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}
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type envelope struct {
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XMLName xml.Name `xml:"http://schemas.xmlsoap.org/soap/envelope/ Envelope"`
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EncodingStyle string `xml:"http://schemas.xmlsoap.org/soap/envelope/ encodingStyle,attr"`
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Body body `xml:"http://schemas.xmlsoap.org/soap/envelope/ Body"`
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}
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type body struct {
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Fault *Fault `xml:"Fault"`
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Action *Action `xml:",any"`
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}
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