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Begin hacking on a pure Go SAML 2.0 implementation
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‎LICENSE

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Apache License
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Version 2.0, January 2004
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http://www.apache.org/licenses/
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8. Limitation of Liability. In no event and under no legal theory,
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‎s2example/demo.go

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package main
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import (
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"io"
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"net/http"
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"github.com/russellhaering/gosaml2"
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"github.com/russellhaering/goxmldsig"
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)
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func main() {
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sp := &saml2.SAMLServiceProvider{
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IdentityProviderSSOURL: "https://dev-116807.oktapreview.com/app/scaleftdev116807_scaleft_1/exk5zt0r12Edi4rD20h7/sso/saml",
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IdentityProviderIssuer: "http://www.okta.com/exk5zt0r12Edi4rD20h7",
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AssertionConsumerServiceURL: "http://localhost:8080/v1/_saml_callback",
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SignAuthnRequests: true,
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IDPCertificateStore: nil,
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SPKeyStore: dsig.RandomKeyStoreForTest(),
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}
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http.HandleFunc("/v1/_saml_callback", func(rw http.ResponseWriter, req *http.Request) {
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err := req.ParseForm()
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if err != nil {
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panic(err)
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}
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err = sp.ValidateEncodedResponse(req.FormValue("SAMLResponse"))
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if err != nil {
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panic(err)
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}
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io.WriteString(rw, "nope")
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})
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authUrl, err := sp.BuildAuthURL("")
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if err != nil {
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panic(err)
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}
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println(authUrl)
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err = http.ListenAndServe(":8080", nil)
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if err != nil {
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panic(err)
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}
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}

‎saml.go

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package saml2
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import (
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"bytes"
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"encoding/base64"
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"net/url"
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"time"
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"github.com/beevik/etree"
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"github.com/russellhaering/goxmldsig"
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"github.com/satori/go.uuid"
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)
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const issueInstantFormat = "2006-01-02T15:04:05"
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type SAMLServiceProvider struct {
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IdentityProviderSSOURL string
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IdentityProviderIssuer string
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AssertionConsumerServiceURL string
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SignAuthnRequests bool
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IDPCertificateStore dsig.X509CertificateStore
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SPKeyStore dsig.X509KeyStore
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}
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func (sp *SAMLServiceProvider) signingContext() *dsig.SigningContext {
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return dsig.NewDefaultSigningContext(sp.SPKeyStore)
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}
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func (sp *SAMLServiceProvider) validationContext() *dsig.ValidationContext {
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return dsig.NewDefaultValidationContext(sp.IDPCertificateStore)
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}
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func (sp *SAMLServiceProvider) BuildAuthRequest() (string, error) {
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authnRequest := &etree.Element{
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Space: "samlp",
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Tag: "AuthnRequest",
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}
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authnRequest.CreateAttr("xmlns:samlp", "urn:oasis:names:tc:SAML:2.0:protocol")
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authnRequest.CreateAttr("xmlns:saml", "urn:oasis:names:tc:SAML:2.0:assertion")
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authnRequest.CreateAttr("ID", "_"+uuid.NewV4().String())
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authnRequest.CreateAttr("Version", "2.0")
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authnRequest.CreateAttr("ProtocolBinding", "urn:oasis:names:tc:SAML:2.0:bindings:HTTP-POST")
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authnRequest.CreateAttr("AssertionConsumerServiceURL", sp.AssertionConsumerServiceURL)
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authnRequest.CreateAttr("AssertionConsumerServiceIndex", "0")
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authnRequest.CreateAttr("AttributeConsumingServiceIndex", "0")
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authnRequest.CreateAttr("IssueInstant", time.Now().UTC().Format(issueInstantFormat))
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authnRequest.CreateElement("saml:Issuer").SetText(sp.IdentityProviderIssuer)
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nameIdPolicy := authnRequest.CreateElement("samlp:NameIDPolicy")
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nameIdPolicy.CreateAttr("AllowCreate", "true")
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nameIdPolicy.CreateAttr("Format", "urn:oasis:names:tc:SAML:2.0:nameid-format:transient")
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requestedAuthnContext := authnRequest.CreateElement("samlp:RequestedAuthnContext")
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requestedAuthnContext.CreateAttr("Comparison", "exact")
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authnContextClassRef := requestedAuthnContext.CreateElement("saml:AuthnContextClassRef")
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authnContextClassRef.SetText("urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport")
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var doc *etree.Document
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if sp.SignAuthnRequests {
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signed, err := sp.signingContext().SignEnveloped(authnRequest)
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if err != nil {
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return "", err
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}
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doc = etree.CreateDocument(signed)
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} else {
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doc = etree.CreateDocument(authnRequest)
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}
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buf := &bytes.Buffer{}
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_, err := doc.WriteTo(buf)
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if err != nil {
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return "", err
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}
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return doc.WriteToString()
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}
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func (sp *SAMLServiceProvider) BuildAuthURL(relayState string) (string, error) {
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parsedUrl, err := url.Parse(sp.IdentityProviderSSOURL)
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if err != nil {
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return "", err
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}
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authnRequest, err := sp.BuildAuthRequest()
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if err != nil {
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return "", err
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}
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qs := parsedUrl.Query()
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qs.Add("SAMLRequest", base64.StdEncoding.EncodeToString([]byte(authnRequest)))
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if relayState != "" {
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qs.Add("RelayState", relayState)
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}
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parsedUrl.RawQuery = qs.Encode()
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return parsedUrl.String(), nil
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}
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func (sp *SAMLServiceProvider) ValidateEncodedResponse(encodedResponse string) error {
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raw, err := base64.StdEncoding.DecodeString(encodedResponse)
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if err != nil {
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return err
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}
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doc := etree.NewDocument()
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err = doc.ReadFromBytes(raw)
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if err != nil {
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return err
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}
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_, err = sp.validationContext().Validate(doc.Root())
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if err != nil {
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return err
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}
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return nil
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}

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