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all: stabilize client OAuth support (#861)

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Also fix lint errors that were hidden because of the build tag.
This commit is contained in:
Maciej Kisiel 2026-03-31 12:36:31 +02:00 • committed by GitHub
commit 638d404e0d
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13 changed files with 387 additions and 915 deletions
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2
oauthex/auth_meta.go
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@ -5,8 +5,6 @@
// This file implements Authorization Server Metadata.
// See https://www.rfc-editor.org/rfc/rfc8414.html.
//go:build mcp_go_client_oauth
package oauthex
import (

2
oauthex/auth_meta_test.go
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@ -2,8 +2,6 @@
// Use of this source code is governed by an MIT-style
// license that can be found in the LICENSE file.
//go:build mcp_go_client_oauth
package oauthex
import (

2
oauthex/client.go
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@ -2,8 +2,6 @@
// Use of this source code is governed by an MIT-style
// license that can be found in the LICENSE file.
//go:build mcp_go_client_oauth
package oauthex
import "errors"

2
oauthex/dcr.go
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@ -5,8 +5,6 @@
// This file implements Authorization Server Metadata.
// See https://www.rfc-editor.org/rfc/rfc8414.html.
//go:build mcp_go_client_oauth
package oauthex
import (

2
oauthex/dcr_test.go
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@ -2,8 +2,6 @@
// Use of this source code is governed by an MIT-style
// license that can be found in the LICENSE file.
//go:build mcp_go_client_oauth
package oauthex
import (

2
oauthex/oauth2.go
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@ -4,8 +4,6 @@
// Package oauthex implements extensions to OAuth2.
//go:build mcp_go_client_oauth
package oauthex
import (

2
oauthex/oauthex_test.go
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@ -2,8 +2,6 @@
// Use of this source code is governed by an MIT-style
// license that can be found in the LICENSE file.
//go:build mcp_go_client_oauth
package oauthex
import (

155
oauthex/resource_meta.go
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@ -5,8 +5,6 @@
// This file implements Protected Resource Metadata.
// See https://www.rfc-editor.org/rfc/rfc9728.html.
//go:build mcp_go_client_oauth
package oauthex
import (
@ -14,81 +12,108 @@ import (
"errors"
"fmt"
"net/http"
"net/url"
"path"
"strings"
"unicode"
"github.com/modelcontextprotocol/go-sdk/internal/util"
)
const defaultProtectedResourceMetadataURI = "/.well-known/oauth-protected-resource"
// ProtectedResourceMetadata is the metadata for an OAuth 2.0 protected resource,
// as defined in section 2 of https://www.rfc-editor.org/rfc/rfc9728.html.
//
// The following features are not supported:
// - additional keys (§2, last sentence)
// - human-readable metadata (§2.1)
// - signed metadata (§2.2)
type ProtectedResourceMetadata struct {
// Resource (resource) is the protected resource's resource identifier.
// Required.
Resource string `json:"resource"`
// GetProtectedResourceMetadataFromID issues a GET request to retrieve protected resource
// metadata from a resource server by its ID.
// The resource ID is an HTTPS URL, typically with a host:port and possibly a path.
// For example:
//
// https://example.com/server
//
// This function, following the spec (§3), inserts the default well-known path into the
// URL. In our example, the result would be
//
// https://example.com/.well-known/oauth-protected-resource/server
//
// It then retrieves the metadata at that location using the given client (or the
// default client if nil) and validates its resource field against resourceID.
//
// Deprecated: Use [GetProtectedResourceMetadata] instead. This function will be removed in v1.5.0.
func GetProtectedResourceMetadataFromID(ctx context.Context, resourceID string, c *http.Client) (_ *ProtectedResourceMetadata, err error) {
defer util.Wrapf(&err, "GetProtectedResourceMetadataFromID(%q)", resourceID)
// AuthorizationServers (authorization_servers) is an optional slice containing a list of
// OAuth authorization server issuer identifiers (as defined in RFC 8414) that can be
// used with this protected resource.
AuthorizationServers []string `json:"authorization_servers,omitempty"`
u, err := url.Parse(resourceID)
if err != nil {
return nil, err
}
// Insert well-known URI into URL.
u.Path = path.Join(defaultProtectedResourceMetadataURI, u.Path)
return GetProtectedResourceMetadata(ctx, u.String(), resourceID, c)
// JWKSURI (jwks_uri) is an optional URL of the protected resource's JSON Web Key (JWK) Set
// document. This contains public keys belonging to the protected resource, such as
// signing key(s) that the resource server uses to sign resource responses.
JWKSURI string `json:"jwks_uri,omitempty"`
// ScopesSupported (scopes_supported) is a recommended slice containing a list of scope
// values (as defined in RFC 6749) used in authorization requests to request access
// to this protected resource.
ScopesSupported []string `json:"scopes_supported,omitempty"`
// BearerMethodsSupported (bearer_methods_supported) is an optional slice containing
// a list of the supported methods of sending an OAuth 2.0 bearer token to the
// protected resource. Defined values are "header", "body", and "query".
BearerMethodsSupported []string `json:"bearer_methods_supported,omitempty"`
// ResourceSigningAlgValuesSupported (resource_signing_alg_values_supported) is an optional
// slice of JWS signing algorithms (alg values) supported by the protected
// resource for signing resource responses.
ResourceSigningAlgValuesSupported []string `json:"resource_signing_alg_values_supported,omitempty"`
// ResourceName (resource_name) is a human-readable name of the protected resource
// intended for display to the end user. It is RECOMMENDED that this field be included.
// This value may be internationalized.
ResourceName string `json:"resource_name,omitempty"`
// ResourceDocumentation (resource_documentation) is an optional URL of a page containing
// human-readable information for developers using the protected resource.
// This value may be internationalized.
ResourceDocumentation string `json:"resource_documentation,omitempty"`
// ResourcePolicyURI (resource_policy_uri) is an optional URL of a page containing
// human-readable policy information on how a client can use the data provided.
// This value may be internationalized.
ResourcePolicyURI string `json:"resource_policy_uri,omitempty"`
// ResourceTOSURI (resource_tos_uri) is an optional URL of a page containing the protected
// resource's human-readable terms of service. This value may be internationalized.
ResourceTOSURI string `json:"resource_tos_uri,omitempty"`
// TLSClientCertificateBoundAccessTokens (tls_client_certificate_bound_access_tokens) is an
// optional boolean indicating support for mutual-TLS client certificate-bound
// access tokens (RFC 8705). Defaults to false if omitted.
TLSClientCertificateBoundAccessTokens bool `json:"tls_client_certificate_bound_access_tokens,omitempty"`
// AuthorizationDetailsTypesSupported (authorization_details_types_supported) is an optional
// slice of 'type' values supported by the resource server for the
// 'authorization_details' parameter (RFC 9396).
AuthorizationDetailsTypesSupported []string `json:"authorization_details_types_supported,omitempty"`
// DPOPSigningAlgValuesSupported (dpop_signing_alg_values_supported) is an optional
// slice of JWS signing algorithms supported by the resource server for validating
// DPoP proof JWTs (RFC 9449).
DPOPSigningAlgValuesSupported []string `json:"dpop_signing_alg_values_supported,omitempty"`
// DPOPBoundAccessTokensRequired (dpop_bound_access_tokens_required) is an optional boolean
// specifying whether the protected resource always requires the use of DPoP-bound
// access tokens (RFC 9449). Defaults to false if omitted.
DPOPBoundAccessTokensRequired bool `json:"dpop_bound_access_tokens_required,omitempty"`
// SignedMetadata (signed_metadata) is an optional JWT containing metadata parameters
// about the protected resource as claims. If present, these values take precedence
// over values conveyed in plain JSON.
// TODO:implement.
// Note that §2.2 says it's okay to ignore this.
// SignedMetadata string `json:"signed_metadata,omitempty"`
}
// GetProtectedResourceMetadataFromHeader retrieves protected resource metadata
// using information in the given header, using the given client (or the default
// client if nil).
// It issues a GET request to a URL discovered by parsing the WWW-Authenticate headers in the given request.
// Per RFC 9728 section 3.3, it validates that the resource field of the resulting metadata
// matches the serverURL (the URL that the client used to make the original request to the resource server).
// If there is no metadata URL in the header, it returns nil, nil.
//
// Deprecated: Use [GetProtectedResourceMetadata] instead. This function will be removed in v1.5.0.
func GetProtectedResourceMetadataFromHeader(ctx context.Context, serverURL string, header http.Header, c *http.Client) (_ *ProtectedResourceMetadata, err error) {
headers := header[http.CanonicalHeaderKey("WWW-Authenticate")]
if len(headers) == 0 {
return nil, nil
}
cs, err := ParseWWWAuthenticate(headers)
if err != nil {
return nil, err
}
metadataURL := resourceMetadataURL(cs)
if metadataURL == "" {
return nil, nil
}
return GetProtectedResourceMetadata(ctx, metadataURL, serverURL, c)
// Challenge represents a single authentication challenge from a WWW-Authenticate header.
// As per RFC 9110, Section 11.6.1, a challenge consists of a scheme and optional parameters.
type Challenge struct {
// Scheme is the authentication scheme (e.g., "Bearer", "Basic").
// It is case-insensitive. A parsed value will always be lower-case.
Scheme string
// Params is a map of authentication parameters.
// Keys are case-insensitive. Parsed keys are always lower-case.
Params map[string]string
}
// resourceMetadataURL returns a resource metadata URL from the given "WWW-Authenticate" header challenges,
// or the empty string if there is none.
func resourceMetadataURL(cs []Challenge) string {
for _, c := range cs {
if u := c.Params["resource_metadata"]; u != "" {
return u
}
}
return ""
}
// GetProtectedResourceMetadataFromID issues a GET request to retrieve protected resource
// GetProtectedResourceMetadata issues a GET request to retrieve protected resource
// metadata from a resource server.
// The metadataURL is typically a URL with a host:port and possibly a path.
// The resourceURL is the resource URI the metadataURL is for.

105
oauthex/resource_meta_public.go
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@ -1,105 +0,0 @@
// Copyright 2025 The Go MCP SDK Authors. All rights reserved.
// Use of this source code is governed by an MIT-style
// license that can be found in the LICENSE file.
// This file implements Protected Resource Metadata.
// See https://www.rfc-editor.org/rfc/rfc9728.html.
// This is a temporary file to expose the required objects to the main package.
package oauthex
// ProtectedResourceMetadata is the metadata for an OAuth 2.0 protected resource,
// as defined in section 2 of https://www.rfc-editor.org/rfc/rfc9728.html.
//
// The following features are not supported:
// - additional keys (§2, last sentence)
// - human-readable metadata (§2.1)
// - signed metadata (§2.2)
type ProtectedResourceMetadata struct {
// Resource (resource) is the protected resource's resource identifier.
// Required.
Resource string `json:"resource"`
// AuthorizationServers (authorization_servers) is an optional slice containing a list of
// OAuth authorization server issuer identifiers (as defined in RFC 8414) that can be
// used with this protected resource.
AuthorizationServers []string `json:"authorization_servers,omitempty"`
// JWKSURI (jwks_uri) is an optional URL of the protected resource's JSON Web Key (JWK) Set
// document. This contains public keys belonging to the protected resource, such as
// signing key(s) that the resource server uses to sign resource responses.
JWKSURI string `json:"jwks_uri,omitempty"`
// ScopesSupported (scopes_supported) is a recommended slice containing a list of scope
// values (as defined in RFC 6749) used in authorization requests to request access
// to this protected resource.
ScopesSupported []string `json:"scopes_supported,omitempty"`
// BearerMethodsSupported (bearer_methods_supported) is an optional slice containing
// a list of the supported methods of sending an OAuth 2.0 bearer token to the
// protected resource. Defined values are "header", "body", and "query".
BearerMethodsSupported []string `json:"bearer_methods_supported,omitempty"`
// ResourceSigningAlgValuesSupported (resource_signing_alg_values_supported) is an optional
// slice of JWS signing algorithms (alg values) supported by the protected
// resource for signing resource responses.
ResourceSigningAlgValuesSupported []string `json:"resource_signing_alg_values_supported,omitempty"`
// ResourceName (resource_name) is a human-readable name of the protected resource
// intended for display to the end user. It is RECOMMENDED that this field be included.
// This value may be internationalized.
ResourceName string `json:"resource_name,omitempty"`
// ResourceDocumentation (resource_documentation) is an optional URL of a page containing
// human-readable information for developers using the protected resource.
// This value may be internationalized.
ResourceDocumentation string `json:"resource_documentation,omitempty"`
// ResourcePolicyURI (resource_policy_uri) is an optional URL of a page containing
// human-readable policy information on how a client can use the data provided.
// This value may be internationalized.
ResourcePolicyURI string `json:"resource_policy_uri,omitempty"`
// ResourceTOSURI (resource_tos_uri) is an optional URL of a page containing the protected
// resource's human-readable terms of service. This value may be internationalized.
ResourceTOSURI string `json:"resource_tos_uri,omitempty"`
// TLSClientCertificateBoundAccessTokens (tls_client_certificate_bound_access_tokens) is an
// optional boolean indicating support for mutual-TLS client certificate-bound
// access tokens (RFC 8705). Defaults to false if omitted.
TLSClientCertificateBoundAccessTokens bool `json:"tls_client_certificate_bound_access_tokens,omitempty"`
// AuthorizationDetailsTypesSupported (authorization_details_types_supported) is an optional
// slice of 'type' values supported by the resource server for the
// 'authorization_details' parameter (RFC 9396).
AuthorizationDetailsTypesSupported []string `json:"authorization_details_types_supported,omitempty"`
// DPOPSigningAlgValuesSupported (dpop_signing_alg_values_supported) is an optional
// slice of JWS signing algorithms supported by the resource server for validating
// DPoP proof JWTs (RFC 9449).
DPOPSigningAlgValuesSupported []string `json:"dpop_signing_alg_values_supported,omitempty"`
// DPOPBoundAccessTokensRequired (dpop_bound_access_tokens_required) is an optional boolean
// specifying whether the protected resource always requires the use of DPoP-bound
// access tokens (RFC 9449). Defaults to false if omitted.
DPOPBoundAccessTokensRequired bool `json:"dpop_bound_access_tokens_required,omitempty"`
// SignedMetadata (signed_metadata) is an optional JWT containing metadata parameters
// about the protected resource as claims. If present, these values take precedence
// over values conveyed in plain JSON.
// TODO:implement.
// Note that §2.2 says it's okay to ignore this.
// SignedMetadata string `json:"signed_metadata,omitempty"`
}
// Challenge represents a single authentication challenge from a WWW-Authenticate header.
// As per RFC 9110, Section 11.6.1, a challenge consists of a scheme and optional parameters.
type Challenge struct {
// Scheme is the authentication scheme (e.g., "Bearer", "Basic").
// It is case-insensitive. A parsed value will always be lower-case.
Scheme string
// Params is a map of authentication parameters.
// Keys are case-insensitive. Parsed keys are always lower-case.
Params map[string]string
}

258
oauthex/resource_meta_test.go Normal file
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@ -0,0 +1,258 @@
// Copyright 2025 The Go MCP SDK Authors. All rights reserved.
// Use of this source code is governed by an MIT-style
// license that can be found in the LICENSE file.
package oauthex
import (
"encoding/json"
"net/http"
"net/http/httptest"
"reflect"
"testing"
)
func TestSplitChallenges(t *testing.T) {
tests := []struct {
name string
input string
want []string
}{
{
name: "single challenge no params",
input: `Basic`,
want: []string{`Basic`},
},
{
name: "single challenge with params",
input: `Bearer realm="example.com", error="invalid_token"`,
want: []string{`Bearer realm="example.com", error="invalid_token"`},
},
{
name: "single challenge with comma in quoted string",
input: `Bearer realm="example, with comma"`,
want: []string{`Bearer realm="example, with comma"`},
},
{
name: "two challenges",
input: `Basic, Bearer realm="example"`,
want: []string{`Basic`, ` Bearer realm="example"`},
},
{
name: "multiple challenges complex",
input: `Newauth realm="apps", Basic, Bearer realm="example.com", error="invalid_token"`,
want: []string{`Newauth realm="apps"`, ` Basic`, ` Bearer realm="example.com", error="invalid_token"`},
},
{
name: "challenge with escaped quote",
input: `Bearer realm="example \"quoted\""`,
want: []string{`Bearer realm="example \"quoted\""`},
},
{
name: "empty input",
input: "",
want: []string{""},
},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
got, err := splitChallenges(tt.input)
if err != nil {
t.Fatal(err)
}
if !reflect.DeepEqual(got, tt.want) {
t.Errorf("splitChallenges() = %v, want %v", got, tt.want)
}
})
}
}
func TestSplitChallengesError(t *testing.T) {
if _, err := splitChallenges(`"Bearer"`); err == nil {
t.Fatal("got nil, want error")
}
}
func TestParseSingleChallenge(t *testing.T) {
tests := []struct {
name string
input string
want Challenge
wantErr bool
}{
{
name: "scheme only",
input: "Basic",
want: Challenge{
Scheme: "basic",
},
wantErr: false,
},
{
name: "scheme with one quoted param",
input: `Bearer realm="example.com"`,
want: Challenge{
Scheme: "bearer",
Params: map[string]string{"realm": "example.com"},
},
wantErr: false,
},
{
name: "scheme with one unquoted param",
input: `Bearer realm=example.com`,
want: Challenge{
Scheme: "bearer",
Params: map[string]string{"realm": "example.com"},
},
wantErr: false,
},
{
name: "scheme with multiple params",
input: `Bearer realm="example", error="invalid_token", error_description="The token expired"`,
want: Challenge{
Scheme: "bearer",
Params: map[string]string{
"realm": "example",
"error": "invalid_token",
"error_description": "The token expired",
},
},
wantErr: false,
},
{
name: "scheme with multiple unquoted params",
input: `Bearer realm=example, error=invalid_token, error_description=The token expired`,
want: Challenge{
Scheme: "bearer",
Params: map[string]string{
"realm": "example",
"error": "invalid_token",
"error_description": "The token expired",
},
},
wantErr: false,
},
{
name: "case-insensitive scheme and keys",
input: `BEARER ReAlM="example"`,
want: Challenge{
Scheme: "bearer",
Params: map[string]string{"realm": "example"},
},
wantErr: false,
},
{
name: "param with escaped quote",
input: `Bearer realm="example \"foo\" bar"`,
want: Challenge{
Scheme: "bearer",
Params: map[string]string{"realm": `example "foo" bar`},
},
wantErr: false,
},
{
name: "param without quotes (token)",
input: "Bearer realm=example.com",
want: Challenge{
Scheme: "bearer",
Params: map[string]string{"realm": "example.com"},
},
wantErr: false,
},
{
name: "malformed param - no value",
input: "Bearer realm=",
wantErr: true,
},
{
name: "malformed param - unterminated quote",
input: `Bearer realm="example`,
wantErr: true,
},
{
name: "malformed param - missing comma",
input: `Bearer realm="a" error="b"`,
wantErr: true,
},
{
name: "malformed param - initial equal",
input: `Bearer ="a"`,
wantErr: true,
},
{
name: "empty input",
input: "",
wantErr: true,
},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
got, err := parseSingleChallenge(tt.input)
if (err != nil) != tt.wantErr {
t.Errorf("parseSingleChallenge() error = %v, wantErr %v", err, tt.wantErr)
return
}
if !reflect.DeepEqual(got, tt.want) {
t.Errorf("parseSingleChallenge() = %v, want %v", got, tt.want)
}
})
}
}
func TestGetProtectedResourceMetadata(t *testing.T) {
ctx := t.Context()
t.Run("Success", func(t *testing.T) {
h := &fakeResourceHandler{}
server := httptest.NewTLSServer(h)
h.installHandlers(server.URL)
client := server.Client()
metadataURL := server.URL + "/.well-known/oauth-protected-resource"
prm, err := GetProtectedResourceMetadata(ctx, metadataURL, server.URL, client)
if err != nil {
t.Fatal(err)
}
if prm == nil {
t.Fatal("nil prm")
}
})
t.Run("RejectsIncorrectResource", func(t *testing.T) {
h := &fakeResourceHandler{resourceOverride: "https://attacker.com/evil"}
server := httptest.NewTLSServer(h)
h.installHandlers(server.URL)
client := server.Client()
metadataURL := server.URL + "/.well-known/oauth-protected-resource"
prm, err := GetProtectedResourceMetadata(ctx, metadataURL, server.URL, client)
if err == nil {
t.Fatal("Expected validation error for mismatched resource, got nil")
}
if prm != nil {
t.Fatal("Expected nil prm on validation failure")
}
})
}
type fakeResourceHandler struct {
http.ServeMux
resourceOverride string // If set, use this instead of correct resource (for testing validation)
}
func (h *fakeResourceHandler) installHandlers(serverURL string) {
path := "/.well-known/oauth-protected-resource"
h.Handle("GET "+path, http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
w.Header().Set("Content-Type", "application/json")
// Per RFC 9728 section 3.3, the resource field should contain the actual resource identifier,
// which is the URL the client uses to access the resource (serverURL + "/resource" for WWW-Authenticate case).
// For the well-known URL test case, it's just the serverURL.
resource := serverURL
// Allow testing with custom resource values (e.g., impersonation attacks).
if h.resourceOverride != "" {
resource = h.resourceOverride
}
prm := &ProtectedResourceMetadata{Resource: resource}
if err := json.NewEncoder(w).Encode(prm); err != nil {
panic(err)
}
}))
}

2
oauthex/token_exchange.go
View file

@ -5,8 +5,6 @@
// This file implements Token Exchange (RFC 8693) for Enterprise Managed Authorization.
// See https://datatracker.ietf.org/doc/html/rfc8693
//go:build mcp_go_client_oauth
package oauthex
import (

2
oauthex/token_exchange_test.go
View file

@ -2,8 +2,6 @@
// Use of this source code is governed by an MIT-style
// license that can be found in the LICENSE file.
//go:build mcp_go_client_oauth
package oauthex
import (

11
oauthex/url_scheme_test.go
View file

@ -2,8 +2,6 @@
// Use of this source code is governed by an MIT-style
// license that can be found in the LICENSE file.
//go:build mcp_go_client_oauth
package oauthex
import (
@ -240,7 +238,7 @@ func TestGetAuthServerMetaRejectsDangerousURLs(t *testing.T) {
}
// TestGetProtectedResourceMetadataRejectsDangerousURLs tests that
// GetProtectedResourceMetadataFromID rejects metadata with dangerous authorization server URLs.
// GetProtectedResourceMetadata rejects metadata with dangerous authorization server URLs.
func TestGetProtectedResourceMetadataRejectsDangerousURLs(t *testing.T) {
server := httptest.NewTLSServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
serverURL := "https://" + r.Host
@ -254,12 +252,13 @@ func TestGetProtectedResourceMetadataRejectsDangerousURLs(t *testing.T) {
defer server.Close()
ctx := context.Background()
_, err := GetProtectedResourceMetadataFromID(ctx, server.URL, server.Client())
metadataURL := server.URL + "/.well-known/oauth-protected-resource"
_, err := GetProtectedResourceMetadata(ctx, metadataURL, server.URL, server.Client())
if err == nil {
t.Fatal("GetProtectedResourceMetadataFromID(): got nil error, want error")
t.Fatal("GetProtectedResourceMetadata(): got nil error, want error")
}
if !strings.Contains(err.Error(), "disallowed scheme") {
t.Errorf("GetProtectedResourceMetadataFromID(): got error %v, want error containing \"disallowed scheme\"", err)
t.Errorf("GetProtectedResourceMetadata(): got error %v, want error containing \"disallowed scheme\"", err)
}
}