tunnel: provide better logging for when iphlpapi fails

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

3 files changed, 12 insertions, 5 deletions

diff --git a/services/errors.go b/services/errors.go
index 8986ebcb..e4fcc77d 100644
--- a/services/errors.go
+++ b/services/errors.go
@@ -61,7 +61,7 @@ func (e Error) Error() string {
 	case ErrorMonitorMTUChanges:
 		return "Unable to monitor default route MTU for changes"
 	case ErrorSetNetConfig:
-		return "Unable to set interface addresses, routes, dns, and/or interface settings"
+		return "Unable to configure adapter network settings"
 	case ErrorTrackTunnels:
 		return "Unable to track existing tunnels"
 	case ErrorEnumerateSessions:
diff --git a/tunnel/addressconfig.go b/tunnel/addressconfig.go
index fba7d770..74ad75b3 100644
--- a/tunnel/addressconfig.go
+++ b/tunnel/addressconfig.go
@@ -7,6 +7,7 @@ package tunnel
 
 import (
 	"bytes"
+	"fmt"
 	"log"
 	"net"
 	"sort"
@@ -105,7 +106,7 @@ func configureInterface(family winipcfg.AddressFamily, conf *conf.Config, luid w
 		err = luid.SetIPAddressesForFamily(family, addresses)
 	}
 	if err != nil {
-		return err
+		return fmt.Errorf("unable to set ips %v: %w", addresses, err)
 	}
 
 	deduplicatedRoutes := make([]*winipcfg.RouteData, 0, len(routes))
@@ -137,6 +138,7 @@ func configureInterface(family winipcfg.AddressFamily, conf *conf.Config, luid w
 	if !conf.Interface.TableOff {
 		err = luid.SetRoutesForFamily(family, deduplicatedRoutes)
 		if err != nil {
+			return fmt.Errorf("unable to set routes %v: %w", deduplicatedRoutes, err)
 			return err
 		}
 	}
@@ -166,10 +168,14 @@ func configureInterface(family winipcfg.AddressFamily, conf *conf.Config, luid w
 	}
 	err = ipif.Set()
 	if err != nil {
-		return err
+		return fmt.Errorf("unable to set metric and MTU: %w", err)
 	}
 
-	return luid.SetDNS(family, conf.Interface.DNS, conf.Interface.DNSSearch)
+	err = luid.SetDNS(family, conf.Interface.DNS, conf.Interface.DNSSearch)
+	if err != nil {
+		return fmt.Errorf("unable to set DNS %v %v: %w", conf.Interface.DNS, conf.Interface.DNSSearch, err)
+	}
+	return nil
 }
 
 func enableFirewall(conf *conf.Config, luid winipcfg.LUID) error {
diff --git a/tunnel/interfacewatcher.go b/tunnel/interfacewatcher.go
index 32132e93..1abc021d 100644
--- a/tunnel/interfacewatcher.go
+++ b/tunnel/interfacewatcher.go
@@ -6,6 +6,7 @@
 package tunnel
 
 import (
+	"fmt"
 	"log"
 	"sync"
 
@@ -145,7 +146,7 @@ func watchInterface() (*interfaceWatcher, error) {
 		iw.setup(iface.Family)
 	})
 	if err != nil {
-		return nil, err
+		return nil, fmt.Errorf("unable to register interface change callback: %w", err)
 	}
 	return iw, nil
 }