feat: add configurable transport-independent CORS policy

examples/cors/main.go

@@ -0,0 +1,76 @@
+package main
+
+import (
+	"errors"
+	"flag"
+	"fmt"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"time"
+
+	omni "git.yuntuo.hk/k2safe/go-omni"
+	"git.yuntuo.hk/k2safe/go-omni/config"
+)
+
+type Config struct {
+	Server config.Config `json:"server"`
+}
+
+func (c Config) Validate() error { return config.AtField("server", c.Server.Validate()) }
+
+func run(path string) error {
+	cfg, err := config.LoadProject(path, Config{Server: config.Default()})
+	if err != nil {
+		return err
+	}
+	a := omni.New(omni.WithConfig(cfg.Server))
+	defer a.Close()
+	a.GET("/private", func(c *omni.Context) error {
+		if c.Header("Authorization") != "Bearer example-only" {
+			return omni.Unauthorized("LOGIN_REQUIRED", "login required")
+		}
+		return c.OK("authenticated")
+	})
+	server := httptest.NewServer(a)
+	defer server.Close()
+	client := &http.Client{Timeout: 3 * time.Second}
+	defer client.CloseIdleConnections()
+	for _, tc := range []struct {
+		method, path, auth string
+		status             int
+	}{{"OPTIONS", "/private", "", 204}, {"GET", "/private", "", 401}, {"GET", "/private", "Bearer example-only", 200}, {"GET", "/missing", "", 404}} {
+		r, _ := http.NewRequest(tc.method, server.URL+tc.path, nil)
+		r.Header.Set("Origin", cfg.Server.CORS.AllowedOrigins[0])
+		if tc.method == "OPTIONS" {
+			r.Header.Set("Access-Control-Request-Method", "GET")
+			r.Header.Set("Access-Control-Request-Headers", "authorization")
+		}
+		if tc.auth != "" {
+			r.Header.Set("Authorization", tc.auth)
+		}
+		res, err := client.Do(r)
+		if err != nil {
+			return err
+		}
+		_, readErr := io.Copy(io.Discard, res.Body)
+		closeErr := res.Body.Close()
+		if err := errors.Join(readErr, closeErr); err != nil {
+			return err
+		}
+		if res.StatusCode != tc.status || res.Header.Get("Access-Control-Allow-Origin") == "" {
+			return fmt.Errorf("unexpected CORS response: %d", res.StatusCode)
+		}
+		fmt.Printf("%s %s -> %d, CORS allowed\n", tc.method, tc.path, res.StatusCode)
+	}
+	return nil
+}
+func main() {
+	path := flag.String("config", "examples/cors/config.yaml", "selected configuration file")
+	flag.Parse()
+	if err := run(*path); err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+}