pbuf struct

next pbuf in singly linked pbuf chain.

pointer to the actual data in the buffer.

total length of this buffer and all next buffers in chain belonging to the same packet. For non-queue packet chains this is the invariant: p->tot_len == p->len + (p->next? p->next->tot_len: 0).

length of this buffer.

a bit field indicating pbuf type and allocation sources (see PBUF_TYPE_FLAG_*, PBUF_ALLOC_FLAG_* and PBUF_TYPE_ALLOC_SRC_MASK).

misc flags.

the reference count always equals the number of pointers that refer to this pbuf. This can be pointers from an application, the stack itself, or pbuf->next pointers from a chain.

For incoming packets, this contains the input netif's index.