lwip_ip4.c File Reference

Determine whether an IP address is in a reserved set of addresses that may not be forwarded, or whether datagrams to that destination may be forwarded.

Parameters:

p	the packet to forward

Returns:

1: can forward 0: discard

Definition at line 232 of file lwip_ip4.c.

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:

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

Definition at line 268 of file lwip_ip4.c.

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 LWIP_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 == LWIP_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 == IP4_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"

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

Same as ip_output_if() but 'src' address is not replaced by netif address when it is 'any'.

Same as ip_output_if_opt() but 'src' address is not replaced by netif address when it is 'any'.

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 == LWIP_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 == IP4_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

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

Parameters:

p	the packet to send (p->payload points to the data, e.g. next protocol header; if dest == LWIP_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 == IP4_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
addr_hint	address 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 374 of file lwip_ip4.c.

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

Definition at line 152 of file lwip_ip4.c.

Source based IPv4 routing must be fully implemented in LWIP_HOOK_IP4_ROUTE_SRC().

This function only provides he parameters.

Definition at line 129 of file lwip_ip4.c.

The default netif used for multicast.

Definition at line 111 of file lwip_ip4.c.

The IP header ID of the next outgoing IP packet.

Definition at line 107 of file lwip_ip4.c.