IPv4. More...

#include <core/system.h>
#include <core/string.h>
#include <net/byteorder.h>
#include <net/inet.h>
#include <net/tcp.h>
#include <aquila/errno.h>

Functions
static int	on_link (struct netif *netif, uint32_t ip)
	Returns whether ip is on netif's link (its network).
static int	is_broadcast (struct netif *netif, uint32_t ip)
	Returns whether ip is a broadcast address on netif's link.
static int	is_loopback (uint32_t ip)
	Returns whether ip is a loopback address (127.0.0.0/8).
int	ipv4_is_local (uint32_t ip)
	Says whether an address is one of ours: a loopback address, or an interface's.
uint32_t	ipv4_source (struct netif *netif, uint32_t dst)
	Chooses the source address of a packet to dst sent through netif.
void	ipv4_input (struct netif netif, struct netbuf nb, const uint8_t src_mac[6])
	Takes in an IPv4 packet that an interface received, and passes it to its protocol.
struct netif *	ipv4_route (uint32_t dst)
	Chooses the interface to send a packet to dst through: the one whose link it is on, or else the first one with a gateway.
int	ipv4_output (struct netif netif, uint32_t src, uint32_t dst, uint8_t proto, struct netbuf nb)
	Sends a packet through an interface: adds its IPv4 header and sends it to dst, or to the gateway if dst isn't on the link, once ARP knows the hardware address.
int	ipv4_send (uint32_t dst, uint8_t proto, struct netbuf *nb)
	Sends a packet to dst, through the interface its route says.

Variables
static uint16_t	ip_id
static const uint8_t	ether_broadcast [6] = {0xff, 0xff, 0xff, 0xff, 0xff, 0xff}

Detailed Description

IPv4.

A packet for us goes to its protocol: ICMP, UDP or TCP. A packet to send gets its IPv4 header here, and goes to its destination directly if that is on the interface's link, or through the interface's gateway otherwise. Fragments aren't supported either way: a fragment that arrives is dropped, and what is sent is never fragmented.

Definition in file ipv4.c.

Function Documentation

◆ ipv4_input()

void ipv4_input	(	struct netif *	netif,
		struct netbuf *	nb,
		const uint8_t	src_mac[6] )

Takes in an IPv4 packet that an interface received, and passes it to its protocol.

A packet that is malformed, not for us, or a fragment is dropped; one for a protocol we don't have gets a "protocol unreachable".

Parameters

netif	the interface it came in on
nb	the packet, from its IPv4 header; it is freed or passed on
src_mac	the sender's MAC address, to update ARP's cache

Definition at line 84 of file ipv4.c.

References arp_update(), netbuf::data, ipv4_hdr::dst, netif::flags, ipv4_hdr::frag, icmp_input(), icmp_unreachable(), inet_checksum(), netif::ip, IP_PROTO_ICMP, IP_PROTO_TCP, IP_PROTO_UDP, ipv4_input(), ipv4_is_local(), is_broadcast(), ipv4_hdr::len, netbuf::len, netbuf_free(), netbuf_pull(), NETIF_LOOPBACK, ntohs, on_link(), ipv4_hdr::proto, ipv4_hdr::src, netif::stats, tcp_input(), udp_input(), and ipv4_hdr::ver_ihl.

Referenced by ether_input(), ipv4_input(), and net_main().

◆ ipv4_is_local()

int ipv4_is_local ( uint32_t ip )

Says whether an address is one of ours: a loopback address, or an interface's.

Parameters

ip	the address, in network byte order

Returns: 1 if it is ours, 0 if not

Definition at line 48 of file ipv4.c.

References netif::ip, ipv4_is_local(), is_loopback(), netifs, and netif::next.

Referenced by icmp_input(), ipv4_input(), ipv4_is_local(), ipv4_output(), ipv4_source(), socket_inet_bind(), socket_tcp_bind(), tcp_input(), and udp_input().

◆ ipv4_output()

int ipv4_output	(	struct netif *	netif,
		uint32_t	src,
		uint32_t	dst,
		uint8_t	proto,
		struct netbuf *	nb )

Sends a packet through an interface: adds its IPv4 header and sends it to dst, or to the gateway if dst isn't on the link, once ARP knows the hardware address.

A packet to one of our own addresses loops back. The netbuf is freed (or kept by ARP until it can be sent).

Parameters

netif	the interface
src	the source address, or 0 for ipv4_source()'s
dst	the destination
proto	the protocol (IP_PROTO_*)
nb	the payload, with room for the headers before it