修改了restoreCommand时：（1）topics指针未申请内存的问题；（2）unsub误写为sub的问题。

Signed-off-by: LeonLi <liting6680@gmail.com>

src/MQTTAsync.c

@@ -718,6 +718,12 @@ static MQTTAsync_queuedCommand* MQTTAsync_restoreCommand(char* buffer, int bufle
 		case SUBSCRIBE:
 			command->details.sub.count = *(int*)ptr;
 			ptr += sizeof(int);
+			
+			if (command->details.sub.count > 0)
+			{
+					command->details.sub.topics = (char **)malloc(sizeof(char *) * command->details.sub.count);
+					command->details.sub.qoss = (int *)malloc(sizeof(int) * command->details.sub.count);
+			}
 
 			for (i = 0; i < command->details.sub.count; ++i)
 			{
@@ -733,8 +739,13 @@ static MQTTAsync_queuedCommand* MQTTAsync_restoreCommand(char* buffer, int bufle
 			break;
 
 		case UNSUBSCRIBE:
-			command->details.sub.count = *(int*)ptr;
+			command->details.unsub.count = *(int*)ptr;
 			ptr += sizeof(int);
+			
+			if (command->details.unsub.count > 0)
+			{
+					command->details.unsub.topics = (char **)malloc(sizeof(char *) * command->details.unsub.count);					
+			}
 
 			for (i = 0; i < command->details.unsub.count; ++i)
 			{