feat: add HTTP client option to OAuthConfig

It's already possible to customize the underlying client used by the SSE and streamable HTTP transports, but not the OAuth handler. This adds an option to customize the underlying client used by the OAuth handler.

Author: sd2k

client/transport/oauth.go

@@ -34,6 +34,9 @@ type OAuthConfig struct {
 AuthServerMetadataURL string
 // PKCEEnabled enables PKCE for the OAuth flow (recommended for public clients)
 PKCEEnabled bool
+// An optional HTTP client to use for requests.
+// If not provided, a default HTTP client will be used.
+HTTPClient *http.Client
 }
 
 // TokenStore is an interface for storing and retrieving OAuth tokens.
@@ -151,10 +154,13 @@ func NewOAuthHandler(config OAuthConfig) *OAuthHandler {
 if config.TokenStore == nil {
 config.TokenStore = NewMemoryTokenStore()
 }
+if config.HTTPClient == nil {
+config.HTTPClient = &http.Client{Timeout: 30 * time.Second}
+}
 
 return &OAuthHandler{
 config: config,
-httpClient: &http.Client{Timeout: 30 * time.Second},
+httpClient: config.HTTPClient,
 }
 }