tcp_echo_server malloc buff is not cleared, and the reception is garbled

[hh-kai]

void alloc_buffer(uv_handle_t *handle, size_t suggested_size, uv_buf_t buf) {
buf->base = (char) malloc(suggested_size);
memset(buf->base, 0, suggested_size); // set 0
buf->len = suggested_size;
}

After malloc, memset should be added, otherwise the received data may be scrambled. Actually, the test will be scrambled