chore: import upstream snapshot with attribution
This commit is contained in:
wehub-resource-sync
@@ -0,0 +1,287 @@
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// Package oauth provides OAuth 2.0 Protected Resource Metadata (RFC 9728) support
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// for the GitHub MCP Server HTTP mode.
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package oauth
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import (
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"fmt"
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"net/http"
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"strings"
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"github.com/github/github-mcp-server/pkg/http/headers"
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"github.com/github/github-mcp-server/pkg/utils"
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"github.com/go-chi/chi/v5"
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"github.com/modelcontextprotocol/go-sdk/auth"
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"github.com/modelcontextprotocol/go-sdk/oauthex"
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)
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const (
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// OAuthProtectedResourcePrefix is the well-known path prefix for OAuth protected resource metadata.
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OAuthProtectedResourcePrefix = "/.well-known/oauth-protected-resource"
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)
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// SupportedScopes lists every OAuth scope that an MCP tool may require. It is the
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// source of truth in two places: HTTP mode advertises it as scopes_supported in
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// the protected-resource metadata, and stdio OAuth login requests it by default
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// and then filters the exposed tools to the granted scopes. A tool whose required
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// scope is absent here is therefore hidden under default OAuth even though a PAT
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// carrying that scope would expose it, so keep this list in sync with tool scope
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// requirements when scopes change.
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var SupportedScopes = []string{
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"repo",
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"read:org",
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"read:user",
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"user:email",
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"read:packages",
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"write:packages",
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"read:project",
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"project",
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"gist",
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"notifications",
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"workflow",
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"codespace",
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}
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// Config holds the OAuth configuration for the MCP server.
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type Config struct {
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// BaseURL is the publicly accessible URL where this server is hosted.
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// This is used to construct the OAuth resource URL.
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BaseURL string
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// AuthorizationServer is the OAuth authorization server URL.
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// Defaults to GitHub's OAuth server if not specified.
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AuthorizationServer string
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// ResourcePath is the externally visible base path for the MCP server (e.g., "/mcp").
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// This is used to restore the original path when a proxy strips a base path before forwarding.
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// If empty, requests are treated as already using the external path.
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ResourcePath string
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// TrustProxyHeaders indicates whether X-Forwarded-Host and X-Forwarded-Proto
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// should be honored when deriving the effective host and scheme for OAuth
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// resource URLs. This must only be enabled when the server is deployed
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// behind a trusted proxy that sets these headers; otherwise an untrusted
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// client can influence the OAuth resource metadata URL advertised to MCP
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// clients. When BaseURL is set, it always takes precedence and these
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// headers are unused.
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TrustProxyHeaders bool
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}
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// AuthHandler handles OAuth-related HTTP endpoints.
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type AuthHandler struct {
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cfg *Config
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apiHost utils.APIHostResolver
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}
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// NewAuthHandler creates a new OAuth auth handler.
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func NewAuthHandler(cfg *Config, apiHost utils.APIHostResolver) (*AuthHandler, error) {
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if cfg == nil {
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cfg = &Config{}
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}
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if apiHost == nil {
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var err error
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apiHost, err = utils.NewAPIHost("https://api.github.com")
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if err != nil {
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return nil, fmt.Errorf("failed to create default API host: %w", err)
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}
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}
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return &AuthHandler{
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cfg: cfg,
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apiHost: apiHost,
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}, nil
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}
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// routePatterns defines the route patterns for OAuth protected resource metadata.
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var routePatterns = []string{
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"", // Root: /.well-known/oauth-protected-resource
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"/readonly", // Read-only mode
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"/insiders", // Insiders mode
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"/x/{toolset}",
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"/x/{toolset}/readonly",
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}
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// RegisterRoutes registers the OAuth protected resource metadata routes.
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func (h *AuthHandler) RegisterRoutes(r chi.Router) {
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for _, pattern := range routePatterns {
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for _, route := range h.routesForPattern(pattern) {
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path := OAuthProtectedResourcePrefix + route
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r.Handle(path, h.metadataHandler())
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}
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}
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}
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func (h *AuthHandler) metadataHandler() http.Handler {
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return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
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ctx := r.Context()
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resourcePath := resolveResourcePath(
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strings.TrimPrefix(r.URL.Path, OAuthProtectedResourcePrefix),
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h.cfg.ResourcePath,
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)
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resourceURL := h.buildResourceURL(r, resourcePath)
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var authorizationServerURL string
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if h.cfg.AuthorizationServer != "" {
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authorizationServerURL = h.cfg.AuthorizationServer
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} else {
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authURL, err := h.apiHost.AuthorizationServerURL(ctx)
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if err != nil {
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http.Error(w, fmt.Sprintf("failed to resolve authorization server URL: %v", err), http.StatusInternalServerError)
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return
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}
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authorizationServerURL = authURL.String()
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}
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metadata := &oauthex.ProtectedResourceMetadata{
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Resource: resourceURL,
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AuthorizationServers: []string{authorizationServerURL},
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ResourceName: "GitHub MCP Server",
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ScopesSupported: SupportedScopes,
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BearerMethodsSupported: []string{"header"},
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}
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auth.ProtectedResourceMetadataHandler(metadata).ServeHTTP(w, r)
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})
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}
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// routesForPattern generates route variants for a given pattern.
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// GitHub strips the /mcp prefix before forwarding, so we register both variants:
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// - With /mcp prefix: for direct access or when GitHub doesn't strip
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// - Without /mcp prefix: for when GitHub has stripped the prefix
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func (h *AuthHandler) routesForPattern(pattern string) []string {
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basePaths := []string{""}
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if basePath := normalizeBasePath(h.cfg.ResourcePath); basePath != "" {
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basePaths = append(basePaths, basePath)
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} else {
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basePaths = append(basePaths, "/mcp")
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}
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routes := make([]string, 0, len(basePaths)*2)
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for _, basePath := range basePaths {
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routes = append(routes, joinRoute(basePath, pattern))
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routes = append(routes, joinRoute(basePath, pattern)+"/")
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}
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return routes
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}
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// resolveResourcePath returns the externally visible resource path,
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// restoring the configured base path when proxies strip it before forwarding.
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func resolveResourcePath(path, basePath string) string {
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if path == "" {
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path = "/"
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}
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base := normalizeBasePath(basePath)
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if base == "" {
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return path
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}
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if path == "/" {
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return base
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}
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if path == base || strings.HasPrefix(path, base+"/") {
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return path
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}
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return base + path
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}
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// ResolveResourcePath returns the externally visible resource path for a request.
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// Exported for use by middleware.
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func ResolveResourcePath(r *http.Request, cfg *Config) string {
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basePath := ""
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if cfg != nil {
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basePath = cfg.ResourcePath
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}
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return resolveResourcePath(r.URL.Path, basePath)
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}
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// buildResourceURL constructs the full resource URL for OAuth metadata.
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func (h *AuthHandler) buildResourceURL(r *http.Request, resourcePath string) string {
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host, scheme := GetEffectiveHostAndScheme(r, h.cfg)
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baseURL := fmt.Sprintf("%s://%s", scheme, host)
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if h.cfg.BaseURL != "" {
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baseURL = strings.TrimSuffix(h.cfg.BaseURL, "/")
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}
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if resourcePath == "" {
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resourcePath = "/"
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}
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if !strings.HasPrefix(resourcePath, "/") {
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resourcePath = "/" + resourcePath
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}
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return baseURL + resourcePath
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}
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// GetEffectiveHostAndScheme returns the effective host and scheme for a request.
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//
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// X-Forwarded-Host and X-Forwarded-Proto are only honored when cfg.TrustProxyHeaders
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// is true. Without that opt-in, an untrusted client could otherwise influence the
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// OAuth resource metadata URL advertised to MCP clients.
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func GetEffectiveHostAndScheme(r *http.Request, cfg *Config) (host, scheme string) { //nolint:revive
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trustProxy := cfg != nil && cfg.TrustProxyHeaders
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if trustProxy {
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if fh := r.Header.Get(headers.ForwardedHostHeader); fh != "" {
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host = fh
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}
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}
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if host == "" {
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host = r.Host
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}
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if host == "" {
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host = "localhost"
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}
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if trustProxy {
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if fp := r.Header.Get(headers.ForwardedProtoHeader); fp != "" {
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scheme = strings.ToLower(fp)
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}
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}
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if scheme == "" {
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if r.TLS != nil {
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scheme = "https"
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} else {
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scheme = "http"
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}
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}
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return
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}
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// BuildResourceMetadataURL constructs the full URL to the OAuth protected resource metadata endpoint.
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func BuildResourceMetadataURL(r *http.Request, cfg *Config, resourcePath string) string {
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host, scheme := GetEffectiveHostAndScheme(r, cfg)
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suffix := ""
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if resourcePath != "" && resourcePath != "/" {
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if !strings.HasPrefix(resourcePath, "/") {
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suffix = "/" + resourcePath
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} else {
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suffix = resourcePath
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}
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}
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if cfg != nil && cfg.BaseURL != "" {
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return strings.TrimSuffix(cfg.BaseURL, "/") + OAuthProtectedResourcePrefix + suffix
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}
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return fmt.Sprintf("%s://%s%s%s", scheme, host, OAuthProtectedResourcePrefix, suffix)
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}
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func normalizeBasePath(path string) string {
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trimmed := strings.TrimSpace(path)
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if trimmed == "" || trimmed == "/" {
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return ""
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}
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if !strings.HasPrefix(trimmed, "/") {
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trimmed = "/" + trimmed
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}
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return strings.TrimSuffix(trimmed, "/")
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}
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func joinRoute(basePath, pattern string) string {
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if basePath == "" {
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return pattern
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}
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if pattern == "" {
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return basePath
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}
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if before, ok := strings.CutSuffix(basePath, "/"); ok {
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return before + pattern
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}
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return basePath + pattern
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}
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