find space-delimited ip address anywhere in line

I'd prefer this were more robust and perhaps used a regexp.

main.go

@@ -9,6 +9,7 @@ import (
 	"net"
 	"os"
 	"sort"
+	"strings"
 )
 
 type lines []string
@@ -16,7 +17,19 @@ type lines []string
 func (l lines) Len() int      { return len(l) }
 func (l lines) Swap(i, j int) { l[i], l[j] = l[j], l[i] }
 func (l lines) Less(i, j int) bool {
-	a, b := net.ParseIP(l[i]), net.ParseIP(l[j])
+	var a, b net.IP
+	for _, s := range strings.Fields(l[i]) {
+		a = net.ParseIP(s)
+		if a != nil {
+			break
+		}
+	}
+	for _, s := range strings.Fields(l[j]) {
+		b = net.ParseIP(s)
+		if b != nil {
+			break
+		}
+	}
 	return bytes.Compare(a, b) < 0
 }