Understanding Linux Network Internals

Functions and Variables Featured in This Chapter

Table 13-5 lists the main functions introduced in this chapter, together with the most important global variables and data structures.

Table 13-5. Functions and data involved in protocol handler management

Name	Description
Function
dev_add_pack dev_remove_pack	Add/remove a protocol handler.
register_8022_client unregister_8022_client	Register/unregister an 802.2 protocol. They are defined as wrappers around llc_sap_open and llc_sap_close.
register_snap_client unregister_snap_client	Register/unregister a SNAP client.
llc_sap_open llc_sap_close	Create/remove an SAP.
eth_type_trans	Used by Ethernet devices to extract the higher-layer protocol identifier and classify the frame as unicast/multicast/broadcast.
Variables
netdev_nit	Number of protocol sniffers registered.
ptype_base	Pointer to the data structure containing the registered protocol handler.
ptype_all	Same as ptype_base but applied to protocol sniffers.
snap_list	List of SNAP clients.
Data structure type
struct packet_type	Used to store information about an ETH_P_ XXX protocol handler.
struct datalink_proto	Used to represent a SNAP protocol.