ip.c File Reference

Functions
struct netif *	ip_route (struct ip_addr *dest)
err_t	ip_input (struct pbuf *p, struct netif *inp)

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Detailed Description

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

See also:

ip_frag.c

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Function Documentation

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)

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"

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

struct netif* ip_route

(

struct ip_addr *

dest

)

[read]

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:

dest

the destination IP address for which to find the route

Returns:

the netif on which to send to reach dest

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