vendor: Revert to github.com/jackpal/gateway instead of fork

It now includes all the fixes

GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/3246

vendor/github.com/jackpal/gateway/gateway_common.go

@@ -0,0 +1,129 @@
+package gateway
+
+import (
+	"errors"
+	"net"
+	"strings"
+)
+
+var errNoGateway = errors.New("no gateway found")
+
+func parseWindowsRoutePrint(output []byte) (net.IP, error) {
+	// Windows route output format is always like this:
+	// ===========================================================================
+	// Active Routes:
+	// Network Destination        Netmask          Gateway       Interface  Metric
+	//           0.0.0.0          0.0.0.0      192.168.1.1    192.168.1.100     20
+	// ===========================================================================
+	// I'm trying to pick the active route,
+	// then jump 2 lines and pick the third IP
+	// Not using regex because output is quite standard from Windows XP to 8 (NEEDS TESTING)
+	lines := strings.Split(string(output), "\n")
+	for idx, line := range lines {
+		if strings.HasPrefix(line, "Active Routes:") {
+			if len(lines) <= idx+2 {
+				return nil, errNoGateway
+			}
+
+			fields := strings.Fields(lines[idx+2])
+			if len(fields) < 3 {
+				return nil, errNoGateway
+			}
+
+			ip := net.ParseIP(fields[2])
+			if ip != nil {
+				return ip, nil
+			}
+		}
+	}
+	return nil, errNoGateway
+}
+
+func parseLinuxIPRoute(output []byte) (net.IP, error) {
+	// Linux '/usr/bin/ip route show' format looks like this:
+	// default via 192.168.178.1 dev wlp3s0  metric 303
+	// 192.168.178.0/24 dev wlp3s0  proto kernel  scope link  src 192.168.178.76  metric 303
+	lines := strings.Split(string(output), "\n")
+	for _, line := range lines {
+		fields := strings.Fields(line)
+		if len(fields) >= 3 && fields[0] == "default" {
+			ip := net.ParseIP(fields[2])
+			if ip != nil {
+				return ip, nil
+			}
+		}
+	}
+
+	return nil, errNoGateway
+}
+
+func parseLinuxRoute(output []byte) (net.IP, error) {
+	// Linux route out format is always like this:
+	// Kernel IP routing table
+	// Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
+	// 0.0.0.0         192.168.1.1     0.0.0.0         UG    0      0        0 eth0
+	lines := strings.Split(string(output), "\n")
+	for _, line := range lines {
+		fields := strings.Fields(line)
+		if len(fields) >= 2 && fields[0] == "0.0.0.0" {
+			ip := net.ParseIP(fields[1])
+			if ip != nil {
+				return ip, nil
+			}
+		}
+	}
+
+	return nil, errNoGateway
+}
+
+func parseDarwinRouteGet(output []byte) (net.IP, error) {
+	// Darwin route out format is always like this:
+	//    route to: default
+	// destination: default
+	//        mask: default
+	//     gateway: 192.168.1.1
+	lines := strings.Split(string(output), "\n")
+	for _, line := range lines {
+		fields := strings.Fields(line)
+		if len(fields) >= 2 && fields[0] == "gateway:" {
+			ip := net.ParseIP(fields[1])
+			if ip != nil {
+				return ip, nil
+			}
+		}
+	}
+
+	return nil, errNoGateway
+}
+
+func parseBSDSolarisNetstat(output []byte) (net.IP, error) {
+	// netstat -rn produces the following on FreeBSD:
+	// Routing tables
+	//
+	// Internet:
+	// Destination        Gateway            Flags      Netif Expire
+	// default            10.88.88.2         UGS         em0
+	// 10.88.88.0/24      link#1             U           em0
+	// 10.88.88.148       link#1             UHS         lo0
+	// 127.0.0.1          link#2             UH          lo0
+	//
+	// Internet6:
+	// Destination                       Gateway                       Flags      Netif Expire
+	// ::/96                             ::1                           UGRS        lo0
+	// ::1                               link#2                        UH          lo0
+	// ::ffff:0.0.0.0/96                 ::1                           UGRS        lo0
+	// fe80::/10                         ::1                           UGRS        lo0
+	// ...
+	outputLines := strings.Split(string(output), "\n")
+	for _, line := range outputLines {
+		fields := strings.Fields(line)
+		if len(fields) >= 2 && fields[0] == "default" {
+			ip := net.ParseIP(fields[1])
+			if ip != nil {
+				return ip, nil
+			}
+		}
+	}
+
+	return nil, errNoGateway
+}