Opentracing support

vendor/github.com/openzipkin/zipkin-go-opentracing/zipkin-endpoint.go

@@ -0,0 +1,72 @@
+package zipkintracer
+
+import (
+	"encoding/binary"
+	"net"
+	"strconv"
+	"strings"
+
+	"github.com/openzipkin/zipkin-go-opentracing/thrift/gen-go/zipkincore"
+)
+
+// makeEndpoint takes the hostport and service name that represent this Zipkin
+// service, and returns an endpoint that's embedded into the Zipkin core Span
+// type. It will return a nil endpoint if the input parameters are malformed.
+func makeEndpoint(hostport, serviceName string) (ep *zipkincore.Endpoint) {
+	ep = zipkincore.NewEndpoint()
+
+	// Set the ServiceName
+	ep.ServiceName = serviceName
+
+	if strings.IndexByte(hostport, ':') < 0 {
+		// "<host>" becomes "<host>:0"
+		hostport = hostport + ":0"
+	}
+
+	// try to parse provided "<host>:<port>"
+	host, port, err := net.SplitHostPort(hostport)
+	if err != nil {
+		// if unparsable, return as "undefined:0"
+		return
+	}
+
+	// try to set port number
+	p, _ := strconv.ParseUint(port, 10, 16)
+	ep.Port = int16(p)
+
+	// if <host> is a domain name, look it up
+	addrs, err := net.LookupIP(host)
+	if err != nil {
+		// return as "undefined:<port>"
+		return
+	}
+
+	var addr4, addr16 net.IP
+	for i := range addrs {
+		addr := addrs[i].To4()
+		if addr == nil {
+			// IPv6
+			if addr16 == nil {
+				addr16 = addrs[i].To16() // IPv6 - 16 bytes
+			}
+		} else {
+			// IPv4
+			if addr4 == nil {
+				addr4 = addr // IPv4 - 4 bytes
+			}
+		}
+		if addr16 != nil && addr4 != nil {
+			// IPv4 & IPv6 have been set, we can stop looking further
+			break
+		}
+	}
+	// default to 0 filled 4 byte array for IPv4 if IPv6 only host was found
+	if addr4 == nil {
+		addr4 = make([]byte, 4)
+	}
+
+	// set IPv4 and IPv6 addresses
+	ep.Ipv4 = (int32)(binary.BigEndian.Uint32(addr4))
+	ep.Ipv6 = []byte(addr16)
+	return
+}