mcp: token: handle authorization_code request (pt1) (#5587)

internal/oauth21/token.go

@@ -0,0 +1,34 @@
+package oauth21
+
+import (
+	"fmt"
+	"net/http"
+
+	"github.com/bufbuild/protovalidate-go"
+
+	"github.com/pomerium/pomerium/internal/oauth21/gen"
+)
+
+func ParseTokenRequest(r *http.Request) (*gen.TokenRequest, error) {
+	err := r.ParseForm()
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse form: %w", err)
+	}
+
+	v := &gen.TokenRequest{
+		GrantType:    r.Form.Get("grant_type"),
+		Code:         optionalFormParam(r, "code"),
+		CodeVerifier: optionalFormParam(r, "code_verifier"),
+		ClientId:     optionalFormParam(r, "client_id"),
+		RefreshToken: optionalFormParam(r, "refresh_token"),
+		Scope:        optionalFormParam(r, "scope"),
+		ClientSecret: optionalFormParam(r, "client_secret"),
+	}
+
+	err = protovalidate.Validate(v)
+	if err != nil {
+		return nil, fmt.Errorf("failed to validate token request: %w", err)
+	}
+
+	return v, nil
+}