lib/config: Don't migrate non-HTTPS-URL discovery servers to new path (fixes #3103)

GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/3104

lib/config/config.go

@@ -14,6 +14,7 @@ import (
 	"io/ioutil"
 	"net/url"
 	"os"
+	"path"
 	"sort"
 	"strings"
 
@@ -23,7 +24,7 @@ import (
 
 const (
 	OldestHandledVersion = 10
-	CurrentVersion       = 14
+	CurrentVersion       = 15
 	MaxRescanIntervalS   = 365 * 24 * 60 * 60
 )
 
@@ -201,6 +202,9 @@ func (cfg *Configuration) prepare(myID protocol.DeviceID) {
 	if cfg.Version == 13 {
 		convertV13V14(cfg)
 	}
+	if cfg.Version == 14 {
+		convertV14V15(cfg)
+	}
 
 	// Build a list of available devices
 	existingDevices := make(map[protocol.DeviceID]bool)
@@ -254,6 +258,21 @@ func (cfg *Configuration) prepare(myID protocol.DeviceID) {
 	}
 }
 
+func convertV14V15(cfg *Configuration) {
+	// Undo v0.13.0 broken migration
+
+	for i, addr := range cfg.Options.GlobalAnnServers {
+		switch addr {
+		case "default-v4v2/":
+			cfg.Options.GlobalAnnServers[i] = "default-v4"
+		case "default-v6v2/":
+			cfg.Options.GlobalAnnServers[i] = "default-v6"
+		}
+	}
+
+	cfg.Version = 15
+}
+
 func convertV13V14(cfg *Configuration) {
 	// Not using the ignore cache is the new default. Disable it on existing
 	// configurations.
@@ -307,12 +326,13 @@ func convertV13V14(cfg *Configuration) {
 
 	var newAddrs []string
 	for _, addr := range cfg.Options.GlobalAnnServers {
-		if addr != "default" {
-			uri, err := url.Parse(addr)
-			if err != nil {
-				panic(err)
-			}
-			uri.Path += "v2/"
+		uri, err := url.Parse(addr)
+		if err != nil {
+			// That's odd. Skip the broken address.
+			continue
+		}
+		if uri.Scheme == "https" {
+			uri.Path = path.Join(uri.Path, "v2") + "/"
 			addr = uri.String()
 		}