🦟 internal/httpreq: add DefaultHttpTransportClone

Moved from producer/ipapi for shared use.

Author: database64128

internal/httpreq/httpreq.go

@@ -6,9 +6,11 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
+	"net"
 	"net/http"
 	"net/url"
 	"strings"
+	"time"
 
 	ddnsgo "github.com/database64128/ddns-go"
 )
@@ -75,3 +77,26 @@ func ReadResponseBody(buf *bytes.Buffer, resp *http.Response, maxSize int64) err
 	}
 	return nil
 }
+
+// DefaultHttpTransportClone returns a clone of [http.DefaultTransport] if possible,
+// or a best-effort approximation of the original if it has been changed by user code
+// to a custom implementation.
+func DefaultHttpTransportClone() *http.Transport {
+	transport, ok := http.DefaultTransport.(*http.Transport)
+	if !ok {
+		dialer := net.Dialer{
+			Timeout:   30 * time.Second,
+			KeepAlive: 30 * time.Second,
+		}
+		return &http.Transport{
+			Proxy:                 http.ProxyFromEnvironment,
+			DialContext:           dialer.DialContext,
+			ForceAttemptHTTP2:     true,
+			MaxIdleConns:          100,
+			IdleConnTimeout:       90 * time.Second,
+			TLSHandshakeTimeout:   10 * time.Second,
+			ExpectContinueTimeout: 1 * time.Second,
+		}
+	}
+	return transport.Clone()
+}

producer/ipapi/text.go

@@ -8,7 +8,6 @@ import (
 	"net/http"
 	"net/netip"
 	"sync"
-	"time"
 
 	"github.com/database64128/ddns-go/internal/httpreq"
 	"github.com/database64128/ddns-go/producer"
@@ -150,28 +149,10 @@ func (s *textSource) get(ctx context.Context) (netip.Addr, error) {
 	return addr.Unmap(), nil
 }
 
-func defaultHttpTransportClone() *http.Transport {
-	transport, ok := http.DefaultTransport.(*http.Transport)
-	if !ok {
-		// http.DefaultTransport was changed by user code to some custom implementation,
-		// so here we create a best-effort approximation of the original.
-		return &http.Transport{
-			Proxy: http.ProxyFromEnvironment,
-			// DialContext will be set by caller.
-			ForceAttemptHTTP2:     true,
-			MaxIdleConns:          100,
-			IdleConnTimeout:       90 * time.Second,
-			TLSHandshakeTimeout:   10 * time.Second,
-			ExpectContinueTimeout: 1 * time.Second,
-		}
-	}
-	return transport.Clone()
-}
-
 // defaultHttpClient4 returns an [*http.Client] that behaves like
 // [http.DefaultClient] but forces connections to use IPv4 only.
 var defaultHttpClient4 = sync.OnceValue(func() *http.Client {
-	transport := defaultHttpTransportClone()
+	transport := httpreq.DefaultHttpTransportClone()
 	transport.DialContext = func(ctx context.Context, network, addr string) (net.Conn, error) {
 		switch network {
 		case "tcp":
@@ -188,7 +169,7 @@ var defaultHttpClient4 = sync.OnceValue(func() *http.Client {
 // defaultHttpClient6 returns an [*http.Client] that behaves like
 // [http.DefaultClient] but forces connections to use IPv6 only.
 var defaultHttpClient6 = sync.OnceValue(func() *http.Client {
-	transport := defaultHttpTransportClone()
+	transport := httpreq.DefaultHttpTransportClone()
 	transport.DialContext = func(ctx context.Context, network, addr string) (net.Conn, error) {
 		switch network {
 		case "tcp":