IP stack headers

Overview

Definition of the auxiliary data structures and functions to operate the IP stack headers and checksums

// structs

struct te_ipstack_pseudo_header_ip;
struct te_ipstack_pseudo_header_ip6;
struct vlanhdr;

// global functions

te_errno te_ipstack_calc_l4_cksum(const struct sockaddr* ip_dst_addr, const struct sockaddr* ip_src_addr, const uint8_t next_hdr, const uint8_t* datagram, const size_t datagram_len, uint16_t* cksum_out);
te_errno te_ipstack_prepare_raw_tcpv4_packet(uint8_t* raw_packet, ssize_t* total_size, bool remove_vlan_hdr, struct sockaddr_ll* sadr_ll);
te_errno te_ipstack_mirror_udp_packet(uint8_t* pkt, size_t len);

Detailed Documentation

Definition of the auxiliary data structures and functions to operate the IP stack headers and checksums

Global Functions

te_errno te_ipstack_calc_l4_cksum(const struct sockaddr* ip_dst_addr, const struct sockaddr* ip_src_addr, const uint8_t next_hdr, const uint8_t* datagram, const size_t datagram_len, uint16_t* cksum_out)

Auxiliary function to calculate checksums for L4 datagrams (UDP, TCP) using a so-called pseudo-header in accordance with principles of checksum calculation defined by RFC 793 (in case of underlying IPv4 network) and RFC 2460 (i.e., it takes into account pseudo-header composition peculiarities brought by IPv6) but without taking into account any possible IPv6 routing headers (i.e., it uses IPv6 DST address from the main header)

Parameters:

ip_dst_addr	Destination IPv4/6 address
ip_src_addr	Source IPv4/6 address
next_hdr	L4 protocol ID (i.e., IPPROTO_UDP)
datagram	Buffer containing L4 header and L4 payload
datagram_len	Buffer length
cksum_out	Location for the resulting checksum

Returns:

Status code

te_errno te_ipstack_prepare_raw_tcpv4_packet(uint8_t* raw_packet, ssize_t* total_size, bool remove_vlan_hdr, struct sockaddr_ll* sadr_ll)

Function to prepare raw TCPv4 packet for sending via raw socket. This includes checking headers, filling checksums and removing of the VLAN header to avoid duplication during sending via raw socket. In addition, it prepares the address for sending based on given headers.

Parameters:

raw_packet	Pointer to buffer with headers and payload
total_size	Total size of raw packet
remove_vlan_hdr	Remove all VLAN headers if `true`
sadr_ll	Link local address to filling. May be `NULL`.

Returns:

Status code

te_errno te_ipstack_mirror_udp_packet(uint8_t* pkt, size_t len)

Reverse addresses and ports of a RAW Ethernet/IP[4,6]/UDP packet, so that it can be echoed back.

Parameters:

pkt	UDP packet.
len	Packet length.

Returns:

Status code.