Fix: Vulnerability in Comparison of different type sizes

[FeedehC]

Little change in sizes of for loop iterator "i", from uint16_t to uint32_t, to avoid possible infinite loop, which depends on the value of "plength".
More information in issue: #1000

[Flole998]

Well, now length could potentially overflow so the buffer is incorrectly filled. Also you're still mixing datatypes, an unsigned int and an uint32_t could potentially have different sizes, so I suggest to use unsigned int for the length everywhere.