bugfix: protect addresses from external changes

We need to use copies of slices, not just pointers to them. It helps
to avoid unexpected changes.

Part of #208

Author: oleg-jukovec

CHANGELOG.md

@@ -20,6 +20,7 @@ Versioning](http://semver.org/spec/v2.0.0.html) except to the first release.
 - Missed Role type constants in the connection_pool subpackage (#208)
 - ConnectionPool does not close UnknownRole connections (#208)
 - Segmentation faults in ConnectionPool requests after disconnect (#208)
+- Addresses in ConnectionPool may be changed from an external code (#208)
 
 ## [1.8.0] - 2022-08-17
 

connection_pool/connection_pool.go

@@ -96,7 +96,7 @@ func ConnectWithOpts(addrs []string, connOpts tarantool.Opts, opts OptsPool) (co
 	anyPool := NewEmptyRoundRobin(size)
 
 	connPool = &ConnectionPool{
-		addrs:    addrs,
+		addrs:    make([]string, len(addrs)),
 		connOpts: connOpts,
 		opts:     opts,
 		notify:   notify,
@@ -105,6 +105,7 @@ func ConnectWithOpts(addrs []string, connOpts tarantool.Opts, opts OptsPool) (co
 		roPool:   roPool,
 		anyPool:  anyPool,
 	}
+	copy(connPool.addrs, addrs)
 
 	somebodyAlive := connPool.fillPools()
 	if !somebodyAlive {
@@ -178,7 +179,9 @@ func (connPool *ConnectionPool) Close() []error {
 
 // GetAddrs gets addresses of connections in pool.
 func (connPool *ConnectionPool) GetAddrs() []string {
-	return connPool.addrs
+	cpy := make([]string, len(connPool.addrs))
+	copy(cpy, connPool.addrs)
+	return cpy
 }
 
 // GetPoolInfo gets information of connections (connected status, ro/rw role).

connection_pool/connection_pool_test.go

@@ -244,6 +244,25 @@ func TestRequestOnClosed(t *testing.T) {
 	require.Nilf(t, err, "failed to restart tarantool")
 }
 
+func TestGetPoolInfo(t *testing.T) {
+	server1 := servers[0]
+	server2 := servers[1]
+
+	srvs := []string{server1, server2}
+	expected := []string{server1, server2}
+	connPool, err := connection_pool.Connect(srvs, connOpts)
+	require.Nilf(t, err, "failed to connect")
+	require.NotNilf(t, connPool, "conn is nil after Connect")
+
+	defer connPool.Close()
+
+	srvs[0] = "x"
+	connPool.GetAddrs()[1] = "y"
+	for i, addr := range connPool.GetAddrs() {
+		require.Equal(t, expected[i], addr)
+	}
+}
+
 func TestCall17(t *testing.T) {
 	roles := []bool{false, true, false, false, true}