client: enable ipv6 support in seed brokers

Signed-off-by: Vasiliy Tolstov <[email protected]>

pkg/kgo/client.go

@@ -23,6 +23,7 @@ import (
 	"fmt"
 	"hash/crc32"
 	"math/rand"
+	"net"
 	"reflect"
 	"sort"
 	"strconv"
@@ -129,22 +130,28 @@ func NewClient(opts ...Opt) (*Client, error) {
 	}
 	seeds := make([]hostport, 0, len(cfg.seedBrokers))
 	for _, seedBroker := range cfg.seedBrokers {
-		addr := seedBroker
-		port := int32(9092) // default kafka port
-		if colon := strings.IndexByte(addr, ':'); colon > 0 {
-			port64, err := strconv.ParseInt(addr[colon+1:], 10, 64)
-			if err != nil {
-				return nil, fmt.Errorf("unable to parse addr:port in %q", seedBroker)
-			}
-			addr = addr[:colon]
-			port = int32(port64)
+		colon := strings.LastIndexByte(seedBroker, ':')
+		if colon == -1 { // no port in address, cannot be ipv6, append default port
+			seedBroker += ":9092"
+		} else if colon > 0 && seedBroker[colon-1] != ']' { // ipv6 without port (since port would follow bracket)
+			seedBroker += ":9092"
+		}
+
+		addr, port, err := net.SplitHostPort(seedBroker)
+		if err != nil {
+			return nil, fmt.Errorf("unable to split host port in %q: %w", seedBroker, err)
+		}
+
+		port32, err := strconv.ParseInt(port, 10, 32)
+		if err != nil {
+			return nil, fmt.Errorf("unable to parse port in %q: %w", seedBroker, err)
 		}
 
 		if addr == "localhost" {
 			addr = "127.0.0.1"
 		}
 
-		seeds = append(seeds, hostport{addr, port})
+		seeds = append(seeds, hostport{addr, int32(port32)})
 	}
 
 	ctx, cancel := context.WithCancel(context.Background())