caddytls: Fix TrustedCACerts backwards compatibility (#6889)

* add failing test

* fix ca pool provisioning

* remove unused param

modules/caddytls/connpolicy.go

@@ -798,10 +798,14 @@ func (clientauth *ClientAuthentication) provision(ctx caddy.Context) error {
 
 	// if we have TrustedCACerts explicitly set, create an 'inline' CA and return
 	if len(clientauth.TrustedCACerts) > 0 {
-		clientauth.ca = InlineCAPool{
+		caPool := InlineCAPool{
 			TrustedCACerts: clientauth.TrustedCACerts,
 		}
-		return nil
+		err := caPool.Provision(ctx)
+		if err != nil {
+			return nil
+		}
+		clientauth.ca = caPool
 	}
 
 	// if we don't have any CARaw set, there's not much work to do

modules/caddytls/connpolicy_test.go

@@ -20,6 +20,7 @@ import (
 	"reflect"
 	"testing"
 
+	"github.com/caddyserver/caddy/v2"
 	"github.com/caddyserver/caddy/v2/caddyconfig/caddyfile"
 )
 
@@ -278,3 +279,49 @@ func TestClientAuthenticationUnmarshalCaddyfileWithDirectiveName(t *testing.T) {
 		})
 	}
 }
+
+func TestClientAuthenticationProvision(t *testing.T) {
+	tests := []struct {
+		name    string
+		ca      ClientAuthentication
+		wantErr bool
+	}{
+		{
+			name: "specifying both 'CARaw' and 'TrustedCACerts' produces an error",
+			ca: ClientAuthentication{
+				CARaw:          json.RawMessage(`{"provider":"inline","trusted_ca_certs":["foo"]}`),
+				TrustedCACerts: []string{"foo"},
+			},
+			wantErr: true,
+		},
+		{
+			name: "specifying both 'CARaw' and 'TrustedCACertPEMFiles' produces an error",
+			ca: ClientAuthentication{
+				CARaw:                 json.RawMessage(`{"provider":"inline","trusted_ca_certs":["foo"]}`),
+				TrustedCACertPEMFiles: []string{"foo"},
+			},
+			wantErr: true,
+		},
+		{
+			name: "setting 'TrustedCACerts' provisions the cert pool",
+			ca: ClientAuthentication{
+				TrustedCACerts: []string{test_der_1},
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			err := tt.ca.provision(caddy.Context{})
+			if (err != nil) != tt.wantErr {
+				t.Errorf("ClientAuthentication.provision() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if !tt.wantErr {
+				if tt.ca.ca.CertPool() == nil {
+					t.Error("CertPool is nil, expected non-nil value")
+				}
+			}
+		})
+	}
+}