Merge pull request #771 from wakatime/bugfix/dns

Use host ip address when dns fails

pkg/api/api.go

@@ -2,15 +2,21 @@ package api
 
 import (
 	"errors"
+	"fmt"
 	"net"
 	"net/http"
+	"strings"
 
 	"github.com/wakatime/wakatime-cli/pkg/log"
 )
 
 const (
 	// BaseURL is the base url of the wakatime api.
 	BaseURL = "https://api.wakatime.com/api/v1"
+	// baseIPAddrv4 is the base ip address v4 of the wakatime api.
+	baseIPAddrv4 = "143.244.210.202"
+	// baseIPAddrv6 is the base ip address v6 of the wakatime api.
+	baseIPAddrv6 = "2604:a880:4:1d0::2a7:b000"
 	// DefaultTimeoutSecs is the default timeout used for requests to the wakatime api.
 	DefaultTimeoutSecs = 120
 )
@@ -59,19 +65,51 @@ func NewClient(baseURL string, opts ...Option) *Client {
 func (c *Client) Do(req *http.Request) (*http.Response, error) {
 	resp, err := c.doFunc(c, req)
 	if err != nil {
+		// don't set alternate host if there's a custom api url
+		if !strings.HasPrefix(c.baseURL, BaseURL) {
+			return nil, err
+		}
+
 		var dnsError *net.DNSError
-		if errors.As(err, &dnsError) {
-			log.Warnf("dns error: %s. Retrying with fallback dns resolver", req.URL)
+		if !errors.As(err, &dnsError) {
+			return nil, err
+		}
+
+		t, err := NewTransportWithHostVerificationDisabled()
+		if err != nil {
+			return nil, err
+		}
+
+		c.client = &http.Client{
+			Transport: t,
+		}
 
-			c.client = &http.Client{
-				Transport: NewTransportWithCloudfareDNS(),
-			}
+		var alternateHost = baseIPAddrv4
 
-			return c.doFunc(c, req)
+		if isLocalIPv6() {
+			alternateHost = baseIPAddrv6
 		}
 
-		return nil, err
+		req.URL.Host = alternateHost
+
+		log.Warnf("dns error, it will retry with host ip address '%s'", alternateHost)
+
+		return c.doFunc(c, req)
 	}
 
 	return resp, nil
 }
+
+func isLocalIPv6() bool {
+	conn, err := net.Dial("udp", fmt.Sprintf("%s:80", baseIPAddrv4))
+	if err != nil {
+		log.Warnf("failed dialing to detect default local ip address: %s", err)
+		return true
+	}
+
+	defer conn.Close()
+
+	localAddr := conn.LocalAddr().(*net.UDPAddr)
+
+	return localAddr.IP.To4() == nil
+}

pkg/api/transport.go

@@ -1,16 +1,16 @@
 package api
 
 import (
-	"context"
+	"crypto/tls"
 	"crypto/x509"
-	"net"
 	"net/http"
-	"strings"
 	"time"
 
 	"github.com/wakatime/wakatime-cli/pkg/log"
 )
 
+const serverName = "api.wakatime.com"
+
 // NewTransport initializes a new http.Transport.
 func NewTransport() *http.Transport {
 	return &http.Transport{
@@ -23,31 +23,17 @@ func NewTransport() *http.Transport {
 	}
 }
 
-// NewTransportWithCloudfareDNS initializes a new http.Transport with cloudfare DNS resolver.
-func NewTransportWithCloudfareDNS() *http.Transport {
+// NewTransportWithHostVerificationDisabled initializes a new http.Transport with disabled host verification.
+func NewTransportWithHostVerificationDisabled() (*http.Transport, error) {
 	t := NewTransport()
 
-	t.DialTLSContext = func(ctx context.Context, network, addr string) (net.Conn, error) {
-		r := &net.Resolver{
-			PreferGo: false,
-			Dial: func(ctx context.Context, network, address string) (net.Conn, error) {
-				d := net.Dialer{
-					Timeout: DefaultTimeoutSecs * time.Second,
-				}
-
-				// ipv6 only
-				if strings.HasSuffix(network, "6") {
-					return d.DialContext(ctx, network, "[2606:4700:4700::1111]:53")
-				}
-
-				return d.DialContext(ctx, network, "1.1.1.1:53")
-			},
-		}
-
-		return r.Dial(ctx, network, addr)
+	t.TLSClientConfig = &tls.Config{
+		MinVersion: tls.VersionTLS12,
+		RootCAs:    CACerts(),
+		ServerName: serverName,
 	}
 
-	return t
+	return t, nil
 }
 
 // LazyCreateNewTransport uses the client's Transport if exists, or creates a new one.