From bc972a52ab9de4bd501868ac896173fd38e8d8c7 Mon Sep 17 00:00:00 2001
From: Alvaro Saurin <alvaro.saurin@gmail.com>
Date: Mon, 9 Nov 2015 12:17:18 +0100
Subject: [PATCH] Resolve to a group of names (instead of taking only the first
 one)

---
 probe/endpoint/reporter.go               | 12 ++++--------
 probe/endpoint/resolver.go               | 18 +++++++++---------
 probe/endpoint/resolver_internal_test.go |  6 +++---
 3 files changed, 16 insertions(+), 20 deletions(-)

diff --git a/probe/endpoint/reporter.go b/probe/endpoint/reporter.go
index 24ad580eb..88ef46bf9 100644
--- a/probe/endpoint/reporter.go
+++ b/probe/endpoint/reporter.go
@@ -139,10 +139,8 @@ func (r *Reporter) addConnection(rpt *report.Report, localAddr, remoteAddr strin
 
 		// In case we have a reverse resolution for the IP, we can use it for
 		// the name...
-		if remoteName, err := r.reverseResolver.get(remoteAddr); err == nil {
-			remoteNode = remoteNode.WithMetadata(map[string]string{
-				"name": remoteName,
-			})
+		if remoteNames, err := r.reverseResolver.get(remoteAddr); err == nil {
+			remoteNode = remoteNode.WithSet("name", report.MakeStringSet(remoteNames...))
 		}
 
 		if localIsClient {
@@ -185,10 +183,8 @@ func (r *Reporter) addConnection(rpt *report.Report, localAddr, remoteAddr strin
 
 		// In case we have a reverse resolution for the IP, we can use it for
 		// the name...
-		if remoteName, err := r.reverseResolver.get(remoteAddr); err == nil {
-			remoteNode = remoteNode.WithMetadata(map[string]string{
-				"name": remoteName,
-			})
+		if remoteNames, err := r.reverseResolver.get(remoteAddr); err == nil {
+			remoteNode = remoteNode.WithSet("name", report.MakeStringSet(remoteNames...))
 		}
 
 		if localIsClient {
diff --git a/probe/endpoint/resolver.go b/probe/endpoint/resolver.go
index af11ad3d5..0f816d86e 100644
--- a/probe/endpoint/resolver.go
+++ b/probe/endpoint/resolver.go
@@ -3,7 +3,6 @@ package endpoint
 import (
 	"fmt"
 	"net"
-	"sort"
 	"strings"
 	"time"
 
@@ -44,13 +43,13 @@ func newReverseResolver() *reverseResolver {
 // get the reverse resolution for an IP address if already in the cache, a
 // gcache.NotFoundKeyError error otherwise. Note: it returns one of the
 // possible names that can be obtained for that IP.
-func (r *reverseResolver) get(address string) (string, error) {
+func (r *reverseResolver) get(address string) ([]string, error) {
 	val, err := r.cache.Get(address)
-	if hostname, ok := val.(string); err == nil && ok {
-		return hostname, nil
+	if hostnames, ok := val.([]string); err == nil && ok {
+		return hostnames, nil
 	}
 	if _, ok := val.(struct{}); err == nil && ok {
-		return "", errNotFound
+		return nil, errNotFound
 	}
 	if err == gcache.NotFoundKeyError {
 		// We trigger a asynchronous reverse resolution when not cached.
@@ -59,7 +58,7 @@ func (r *reverseResolver) get(address string) (string, error) {
 		default:
 		}
 	}
-	return "", errNotFound
+	return nil, errNotFound
 }
 
 func (r *reverseResolver) loop() {
@@ -71,9 +70,10 @@ func (r *reverseResolver) loop() {
 		<-r.Throttle // rate limit our DNS resolutions
 		names, err := r.Resolver(request)
 		if err == nil && len(names) > 0 {
-			sort.Strings(names)
-			name := strings.TrimRight(names[0], ".")
-			r.cache.Set(request, name)
+			for idx, name := range names {
+				names[idx] = strings.TrimRight(name, ".")
+			}
+			r.cache.Set(request, names)
 		} else {
 			r.cache.Set(request, struct{}{})
 		}
diff --git a/probe/endpoint/resolver_internal_test.go b/probe/endpoint/resolver_internal_test.go
index a3ac4632e..f10ba5707 100644
--- a/probe/endpoint/resolver_internal_test.go
+++ b/probe/endpoint/resolver_internal_test.go
@@ -29,9 +29,9 @@ func TestReverseResolver(t *testing.T) {
 	revRes.Throttle = time.Tick(time.Millisecond)
 
 	for ip, names := range tests {
-		test.Poll(t, 100*time.Millisecond, names[0], func() interface{} {
-			result, _ := revRes.get(ip)
-			return result
+		test.Poll(t, 100*time.Millisecond, names, func() interface{} {
+			ns, _ := revRes.get(ip)
+			return ns
 		})
 	}
 }