TUN-528: Move cloudflared into a separate repo

origin/discovery.go

@@ -0,0 +1,82 @@
+package origin
+
+import (
+	"fmt"
+	"net"
+)
+
+const (
+	// Used to discover HA Warp servers
+	srvService = "warp"
+	srvProto   = "tcp"
+	srvName    = "cloudflarewarp.com"
+)
+
+func ResolveEdgeIPs(addresses []string) ([]*net.TCPAddr, error) {
+	if len(addresses) > 0 {
+		var tcpAddrs []*net.TCPAddr
+		for _, address := range addresses {
+			// Addresses specified (for testing, usually)
+			tcpAddr, err := net.ResolveTCPAddr("tcp", address)
+			if err != nil {
+				return nil, err
+			}
+			tcpAddrs = append(tcpAddrs, tcpAddr)
+		}
+		return tcpAddrs, nil
+	}
+	// HA service discovery lookup
+	_, addrs, err := net.LookupSRV(srvService, srvProto, srvName)
+	if err != nil {
+		return nil, err
+	}
+	var resolvedIPsPerCNAME [][]*net.TCPAddr
+	var lookupErr error
+	for _, addr := range addrs {
+		ips, err := ResolveSRVToTCP(addr)
+		if err != nil || len(ips) == 0 {
+			// don't return early, we might be able to resolve other addresses
+			lookupErr = err
+			continue
+		}
+		resolvedIPsPerCNAME = append(resolvedIPsPerCNAME, ips)
+	}
+	ips := FlattenServiceIPs(resolvedIPsPerCNAME)
+	if lookupErr == nil && len(ips) == 0 {
+		return nil, fmt.Errorf("Unknown service discovery error")
+	}
+	return ips, lookupErr
+}
+
+func ResolveSRVToTCP(srv *net.SRV) ([]*net.TCPAddr, error) {
+	ips, err := net.LookupIP(srv.Target)
+	if err != nil {
+		return nil, err
+	}
+	addrs := make([]*net.TCPAddr, len(ips))
+	for i, ip := range ips {
+		addrs[i] = &net.TCPAddr{IP: ip, Port: int(srv.Port)}
+	}
+	return addrs, nil
+}
+
+// FlattenServiceIPs transposes and flattens the input slices such that the
+// first element of the n inner slices are the first n elements of the result.
+func FlattenServiceIPs(ipsByService [][]*net.TCPAddr) []*net.TCPAddr {
+	var result []*net.TCPAddr
+	for len(ipsByService) > 0 {
+		filtered := ipsByService[:0]
+		for _, ips := range ipsByService {
+			if len(ips) == 0 {
+				// sanity check
+				continue
+			}
+			result = append(result, ips[0])
+			if len(ips) > 1 {
+				filtered = append(filtered, ips[1:])
+			}
+		}
+		ipsByService = filtered
+	}
+	return result
+}