Add command to fetch a URL

cmd/sing-box/cmd_tools_fetch.go

@@ -0,0 +1,95 @@
+package main
+
+import (
+	"context"
+	"errors"
+	"io"
+	"net"
+	"net/http"
+	"net/url"
+	"os"
+
+	"github.com/sagernet/sing-box/log"
+	"github.com/sagernet/sing/common/bufio"
+	M "github.com/sagernet/sing/common/metadata"
+	N "github.com/sagernet/sing/common/network"
+
+	"github.com/spf13/cobra"
+)
+
+var commandFetchFlagOutbound string
+
+var commandFetch = &cobra.Command{
+	Use:   "fetch",
+	Short: "Fetch an URL",
+	Args:  cobra.MinimumNArgs(1),
+	Run: func(cmd *cobra.Command, args []string) {
+		err := fetch(args)
+		if err != nil {
+			log.Fatal(err)
+		}
+	},
+}
+
+func init() {
+	commandFetch.Flags().StringVar(&commandFetchFlagOutbound, "outbound", "", "outbound tag")
+	commandTools.AddCommand(commandFetch)
+}
+
+var httpClient *http.Client
+
+func fetch(args []string) error {
+	instance, err := createPreStartedClient()
+	if err != nil {
+		return err
+	}
+	defer instance.Close()
+	httpClient = &http.Client{
+		Transport: &http.Transport{
+			DialContext: func(ctx context.Context, network, addr string) (net.Conn, error) {
+				dialer, err := createDialer(instance, N.NetworkTCP, commandFetchFlagOutbound)
+				if err != nil {
+					return nil, err
+				}
+				return dialer.DialContext(ctx, network, M.ParseSocksaddr(addr))
+			},
+			ForceAttemptHTTP2: true,
+		},
+	}
+	defer httpClient.CloseIdleConnections()
+	for _, urlString := range args {
+		parsedURL, err := url.Parse(urlString)
+		if err != nil {
+			return err
+		}
+		switch parsedURL.Scheme {
+		case "":
+			parsedURL.Scheme = "http"
+			fallthrough
+		case "http", "https":
+			err = fetchHTTP(parsedURL)
+			if err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}
+
+func fetchHTTP(parsedURL *url.URL) error {
+	request, err := http.NewRequest("GET", parsedURL.String(), nil)
+	if err != nil {
+		return err
+	}
+	request.Header.Add("User-Agent", "curl/7.88.0")
+	response, err := httpClient.Do(request)
+	if err != nil {
+		return err
+	}
+	defer response.Body.Close()
+	_, err = bufio.Copy(os.Stdout, response.Body)
+	if errors.Is(err, io.EOF) {
+		return nil
+	}
+	return err
+}