This is the IPv4 layer implementation for incoming and outgoing IP traffic.

See Also: ip_frag.c

#include "lwip/opt.h"
#include "lwip/ip.h"
#include "lwip/def.h"
#include "lwip/mem.h"
#include "lwip/ip_frag.h"
#include "lwip/inet_chksum.h"
#include "lwip/netif.h"
#include "lwip/icmp.h"
#include "lwip/igmp.h"
#include "lwip/raw.h"
#include "lwip/udp.h"
#include "lwip/tcp_impl.h"
#include "lwip/snmp.h"
#include "lwip/dhcp.h"
#include "lwip/autoip.h"
#include "lwip/stats.h"
#include "arch/perf.h"
#include <string.h>

Macros
#define	CHECKSUM_GEN_IP_INLINE 0

#define	IP_ACCEPT_LINK_LAYER_ADDRESSING 0

#define	LWIP_INLINE_IP_CHKSUM 1
	Set this to 0 in the rare case of wanting to call an extra function to generate the IP checksum (in contrast to calculating it on-the-fly). More...

Functions
err_t	ip_input (struct pbuf p, struct netif inp)
	This function is called by the network interface device driver when an IP packet is received. More...

err_t	ip_output (struct pbuf p, ip_addr_t src, ip_addr_t *dest, u8_t ttl, u8_t tos, u8_t proto)
	Simple interface to ip_output_if. More...

err_t	ip_output_if (struct pbuf p, ip_addr_t src, ip_addr_t dest, u8_t ttl, u8_t tos, u8_t proto, struct netif netif)
	Sends an IP packet on a network interface. More...

struct netif *	ip_route (ip_addr_t *dest)
	Finds the appropriate network interface for a given IP address. More...

Variables
struct ip_hdr *	current_header
	Header of the input packet currently being processed. More...

ip_addr_t	current_iphdr_dest
	Destination IP address of current_header. More...

ip_addr_t	current_iphdr_src
	Source IP address of current_header. More...

struct netif *	current_netif
	The interface that provided the packet for the current callback invocation. More...

static u16_t	ip_id
	The IP header ID of the next outgoing IP packet. More...

#define CHECKSUM_GEN_IP_INLINE 0

#define IP_ACCEPT_LINK_LAYER_ADDRESSING 0

#define LWIP_INLINE_IP_CHKSUM 1

Set this to 0 in the rare case of wanting to call an extra function to generate the IP checksum (in contrast to calculating it on-the-fly).

err_t ip_input	(	struct pbuf *	p,
		struct netif *	inp
	)

This function is called by the network interface device driver when an IP packet is received.

The function does the basic checks of the IP header such as packet size being at least larger than the header size etc. If the packet was not destined for us, the packet is forwarded (using ip_forward). The IP checksum is always checked.

Finally, the packet is sent to the upper layer protocol input function.

Parameters

p	the received IP packet (p->payload points to IP header)
inp	the netif on which this packet was received

Returns: ERR_OK if the packet was processed (could return ERR_* if it wasn't processed, but currently always returns ERR_OK)

References current_iphdr_dest, current_iphdr_src, ERR_OK, netif::flags, icmp_dest_unreach(), ICMP_DUR_PROTO, icmp_input(), if(), inet_chksum(), ip4_addr_get_u32, netif::ip_addr, ip_addr_cmp, ip_addr_copy, ip_addr_isany, ip_addr_isbroadcast, ip_addr_ismulticast, ip_addr_set_any, IP_DEBUG, ip_debug_print, IP_HLEN, IP_MF, IP_OFFMASK, IP_PROTO_ICMP, IP_PROTO_IGMP, IP_PROTO_TCP, IP_PROTO_UDP, IP_PROTO_UDPLITE, ip_reass(), IP_STATS_INC, IPH_HL, IPH_ID, IPH_LEN, IPH_OFFSET, IPH_PROTO, IPH_V, iphdr, pbuf::len, LWIP_DBG_LEVEL_SERIOUS, LWIP_DBG_LEVEL_WARNING, LWIP_DBG_TRACE, LWIP_DEBUGF, netif::name, NETIF_FLAG_IGMP, netif_is_up, netif_list, netif::netmask, netif::next, ntohs, NULL, pbuf::payload, pbuf_free(), pbuf_realloc(), PP_HTONS, snmp_inc_ipinaddrerrors, snmp_inc_ipindelivers, snmp_inc_ipindiscards, snmp_inc_ipinhdrerrors, snmp_inc_ipinreceives, snmp_inc_ipinunknownprotos, tcp_input(), pbuf::tot_len, udp_input(), X16_F, and X32_F.

Referenced by ethernet_input(), and netif_init().

err_t ip_output	(	struct pbuf *	p,
		ip_addr_t *	src,
		ip_addr_t *	dest,
		u8_t	ttl,
		u8_t	tos,
		u8_t	proto
	)

Simple interface to ip_output_if.

It finds the outgoing network interface and calls upon ip_output_if to do the actual work.

Parameters

p	the packet to send (p->payload points to the data, e.g. next protocol header; if dest == IP_HDRINCL, p already includes an IP header and p->payload points to that IP header)
src	the source IP address to send from (if src == IP_ADDR_ANY, the IP address of the netif used to send is used as source address)
dest	the destination IP address to send the packet to
ttl	the TTL value to be set in the IP header
tos	the TOS value to be set in the IP header
proto	the PROTOCOL to be set in the IP header

Returns: ERR_RTE if no route is found see ip_output_if() for more return values

References ERR_RTE, ip4_addr1_16, ip4_addr2_16, ip4_addr3_16, ip4_addr4_16, IP_DEBUG, ip_output_if(), ip_route(), IP_STATS_INC, LWIP_ASSERT, LWIP_DEBUGF, NULL, and pbuf::ref.

Referenced by icmp_send_response(), tcp_keepalive(), tcp_output_segment(), tcp_rst(), tcp_send_empty_ack(), and tcp_zero_window_probe().

err_t ip_output_if	(	struct pbuf *	p,
		ip_addr_t *	src,
		ip_addr_t *	dest,
		u8_t	ttl,
		u8_t	tos,
		u8_t	proto,
		struct netif *	netif
	)

Sends an IP packet on a network interface.

This function constructs the IP header and calculates the IP header checksum. If the source IP address is NULL, the IP address of the outgoing network interface is filled in as source address. If the destination IP address is IP_HDRINCL, p is assumed to already include an IP header and p->payload points to it instead of the data.

Parameters

p	the packet to send (p->payload points to the data, e.g. next protocol header; if dest == IP_HDRINCL, p already includes an IP header and p->payload points to that IP header)
src	the source IP address to send from (if src == IP_ADDR_ANY, the IP address of the netif used to send is used as source address)
dest	the destination IP address to send the packet to
ttl	the TTL value to be set in the IP header
tos	the TOS value to be set in the IP header
proto	the PROTOCOL to be set in the IP header
netif	the netif on which to send this packet

Returns: ERR_OK if the packet was sent OK ERR_BUF if p doesn't have enough space for IP/LINK headers returns errors returned by netif->output

Note: ip_id: RFC791 "some host may be able to simply use unique identifiers independent of destination"

References NULL.

Referenced by icmp_input(), and ip_output().

struct netif* ip_route ( ip_addr_t * dest )

Finds the appropriate network interface for a given IP address.

It searches the list of network interfaces linearly. A match is found if the masked IP address of the network interface equals the masked IP address given to the function.

Parameters