Handle IPv6 in connection URLs

Previously IPv6 addresses were wrongly split and lead to a parse error.
This commit fixes the behavior.

config.go

@@ -399,13 +399,19 @@ func parseURLSettings(connString string) (map[string]string, error) {
 	var hosts []string
 	var ports []string
 	for _, host := range strings.Split(url.Host, ",") {
-		parts := strings.SplitN(host, ":", 2)
+		if host == "" {
-		if parts[0] != "" {
+			continue
-			hosts = append(hosts, parts[0])
 		}
-		if len(parts) == 2 {
+		if isIPOnly(host) {
-			ports = append(ports, parts[1])
+			hosts = append(hosts, strings.Trim(host, "[]"))
+			continue
 		}
+		h, p, err := net.SplitHostPort(host)
+		if err != nil {
+			return nil, errors.Errorf("failed to split host:port in '%s', err: %w", host, err)
+		}
+		hosts = append(hosts, h)
+		ports = append(ports, p)
 	}
 	if len(hosts) > 0 {
 		settings["host"] = strings.Join(hosts, ",")
@@ -426,6 +432,10 @@ func parseURLSettings(connString string) (map[string]string, error) {
 	return settings, nil
 }
 
+func isIPOnly(host string) bool {
+	return net.ParseIP(strings.Trim(host, "[]")) != nil || !strings.Contains(host, ":")
+}
+
 var asciiSpace = [256]uint8{'\t': 1, '\n': 1, '\v': 1, '\f': 1, '\r': 1, ' ': 1}
 
 func parseDSNSettings(s string) (map[string]string, error) {

config_test.go

@@ -127,11 +127,11 @@ func TestParseConfig(t *testing.T) {
 			name:       "sslmode verify-ca",
 			connString: "postgres://jack:secret@localhost:5432/mydb?sslmode=verify-ca",
 			config: &pgconn.Config{
-				User:          "jack",
+				User:     "jack",
-				Password:      "secret",
+				Password: "secret",
-				Host:          "localhost",
+				Host:     "localhost",
-				Port:          5432,
+				Port:     5432,
-				Database:      "mydb",
+				Database: "mydb",
 				TLSConfig: &tls.Config{
 					InsecureSkipVerify: true,
 				},
@@ -228,6 +228,42 @@ func TestParseConfig(t *testing.T) {
 				RuntimeParams: map[string]string{},
 			},
 		},
+		{
+			name:       "database url IPv4 with port",
+			connString: "postgresql://jack@127.0.0.1:5433/mydb?sslmode=disable",
+			config: &pgconn.Config{
+				User:          "jack",
+				Host:          "127.0.0.1",
+				Port:          5433,
+				Database:      "mydb",
+				TLSConfig:     nil,
+				RuntimeParams: map[string]string{},
+			},
+		},
+		{
+			name:       "database url IPv6 with port",
+			connString: "postgresql://jack@[2001:db8::1]:5433/mydb?sslmode=disable",
+			config: &pgconn.Config{
+				User:          "jack",
+				Host:          "2001:db8::1",
+				Port:          5433,
+				Database:      "mydb",
+				TLSConfig:     nil,
+				RuntimeParams: map[string]string{},
+			},
+		},
+		{
+			name:       "database url IPv6 no port",
+			connString: "postgresql://jack@[2001:db8::1]/mydb?sslmode=disable",
+			config: &pgconn.Config{
+				User:          "jack",
+				Host:          "2001:db8::1",
+				Port:          5432,
+				Database:      "mydb",
+				TLSConfig:     nil,
+				RuntimeParams: map[string]string{},
+			},
+		},
 		{
 			name:       "DSN everything",
 			connString: "user=jack password=secret host=localhost port=5432 dbname=mydb sslmode=disable application_name=pgxtest search_path=myschema",