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Make OAuth Redirect URI Configurable #3

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Merged
merged 2 commits into from
Oct 31, 2025
+130 −6
Merged

Make OAuth Redirect URI Configurable #3

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d54920a
remove hard-coded URL
saucow Oct 27, 2025
07fb032
restrict to localhost or docker URLs
saucow Oct 28, 2025
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11 changes: 9 additions & 2 deletions dcr.go
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Original file line number Diff line number Diff line change
Expand Up @@ -18,15 +18,22 @@ const DefaultRedirectURI = "https://mcp.docker.com/oauth/callback"
// - Uses token_endpoint_auth_method="none" for public clients
// - Includes redirect_uris pointing to mcp-oauth proxy
// - Requests authorization_code and refresh_token grant types
func PerformDCR(ctx context.Context, discovery *Discovery, serverName string) (*ClientCredentials, error) {
//
// redirectURI: The OAuth callback URI to register. If empty, uses DefaultRedirectURI.
func PerformDCR(ctx context.Context, discovery *Discovery, serverName string, redirectURI string) (*ClientCredentials, error) {
if discovery.RegistrationEndpoint == "" {
return nil, fmt.Errorf("no registration endpoint found for %s", serverName)
}

// Use provided redirectURI, fallback to default if empty
if redirectURI == "" {
redirectURI = DefaultRedirectURI
}
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@kgprs kgprs Oct 28, 2025

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When the redirect url is specified, should we add a check that it's either 127.0.0.1 or mcp.docker.com? Might avoid a situation where an attacker passes in their own url

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@kgprs kgprs Oct 29, 2025

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I think we should drop the localhost since an attacker can override it


// Build DCR request for PUBLIC client
registration := DCRRequest{
ClientName: fmt.Sprintf("MCP Gateway - %s", serverName),
RedirectURIs: []string{DefaultRedirectURI},
RedirectURIs: []string{redirectURI},
TokenEndpointAuthMethod: "none", // PUBLIC client (no client secret)
GrantTypes: []string{"authorization_code", "refresh_token"},
ResponseTypes: []string{"code"},
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8 changes: 4 additions & 4 deletions dcr_test.go
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Expand Up @@ -39,8 +39,8 @@ func TestPerformDCR_PublicClient(t *testing.T) {
Scopes: []string{"read", "write"},
}

// Perform DCR
creds, err := PerformDCR(context.Background(), discovery, "test-server")
// Perform DCR (empty redirectURI uses default)
creds, err := PerformDCR(context.Background(), discovery, "test-server", "")
// Verify no error
if err != nil {
t.Fatalf("DCR failed: %v", err)
Expand Down Expand Up @@ -82,8 +82,8 @@ func TestPerformDCR_NoRegistrationEndpoint(t *testing.T) {
RegistrationEndpoint: "", // Empty - DCR not supported
}

// Attempt DCR
creds, err := PerformDCR(context.Background(), discovery, "test-server")
// Attempt DCR (empty redirectURI uses default)
creds, err := PerformDCR(context.Background(), discovery, "test-server", "")

// Verify error occurred
if err == nil {
Expand Down