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ip.c File Reference

ip.c File Reference

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

Go to the source code of this file.

Functions

struct netifip_route (ip_addr_t *dest)
 Finds the appropriate network interface for a given IP address.
static void ip_forward (struct pbuf *p, struct ip_hdr *iphdr, struct netif *inp)
 Forwards an IP packet.
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.

Variables

struct netifcurrent_netif
 The interface that provided the packet for the current callback invocation.
struct ip_hdr * current_header
 Header of the input packet currently being processed.
ip_addr_t current_iphdr_src
 Source IP address of current_header.
ip_addr_t current_iphdr_dest
 Destination IP address of current_header.
static u16_t ip_id
 The IP header ID of the next outgoing IP packet.

Detailed Description

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

See also:
ip_frag.c

Definition in file ip.c.


Function Documentation

static void ip_forward ( struct pbuf *  p,
struct ip_hdr *  iphdr,
struct netif inp 
) [static]

Forwards an IP packet.

It finds an appropriate route for the packet, decrements the TTL value of the packet, adjusts the checksum and outputs the packet on the appropriate interface.

Parameters:
pthe packet to forward (p->payload points to IP header)
iphdrthe IP header of the input packet
inpthe netif on which this packet was received

Definition at line 160 of file ip.c.

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:
pthe received IP packet (p->payload points to IP header)
inpthe 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:
pthe 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)
srcthe 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)
destthe destination IP address to send the packet to
ttlthe TTL value to be set in the IP header
tosthe TOS value to be set in the IP header
protothe PROTOCOL to be set in the IP header
netifthe 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"

Same as ip_output_if() but with the possibility to include IP options:

@ param ip_options pointer to the IP options, copied into the IP header @ param optlen length of ip_options

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

Parameters:
pthe 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)
srcthe 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)
destthe destination IP address to send the packet to
ttlthe TTL value to be set in the IP header
tosthe TOS value to be set in the IP header
protothe PROTOCOL to be set in the IP header
Returns:
ERR_RTE if no route is found see ip_output_if() for more return values

Like ip_output, but takes and addr_hint pointer that is passed on to netif->addr_hint before calling ip_output_if.

Parameters:
pthe 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)
srcthe 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)
destthe destination IP address to send the packet to
ttlthe TTL value to be set in the IP header
tosthe TOS value to be set in the IP header
protothe PROTOCOL to be set in the IP header
addr_hintaddress hint pointer set to netif->addr_hint before calling ip_output_if()
Returns:
ERR_RTE if no route is found see ip_output_if() for more return values

Definition at line 242 of file ip.c.

struct netif* ip_route ( ip_addr_t *  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:
destthe destination IP address for which to find the route
Returns:
the netif on which to send to reach dest

Definition at line 124 of file ip.c.


Variable Documentation

struct ip_hdr* current_header

Header of the input packet currently being processed.

Definition at line 105 of file ip.c.

ip_addr_t current_iphdr_dest

Destination IP address of current_header.

Definition at line 109 of file ip.c.

ip_addr_t current_iphdr_src

Source IP address of current_header.

Definition at line 107 of file ip.c.

The interface that provided the packet for the current callback invocation.

Definition at line 100 of file ip.c.

u16_t ip_id [static]

The IP header ID of the next outgoing IP packet.

Definition at line 112 of file ip.c.