The set of functions which accept, queue, and send packets; Most of your work will go here. More...

#include <stdio.h>
#include <assert.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include "sr_if.h"
#include "sr_rt.h"
#include "sr_router.h"
#include "sr_protocol.h"
#include "sr_arpcache.h"
#include "sr_utils.h"

Include dependency graph for sr_router.c:

Functions
void	sr_init (struct sr_instance *sr)
	Initializes router state.

int	ether_to_me (unsigned char my_address, unsigned char addr_s)
	Determine if an ethernet frame is addressed to a given interface's MAC address. More...

void	sr_handlepacket (struct sr_instance sr, uint8_t packet, unsigned int len, char *interface)
	Called whenever an incoming packet is received; You are responsible for writing this. More...

int	handle_arp (struct sr_instance sr, uint8_t packet, unsigned int len, char *interface)
	Handles all incoming packets with an ARP header; You are responsible for writing this. More...

int	handle_ip (struct sr_instance sr, uint8_t packet, unsigned int len, char *interface)
	Handles all incoming packets with an IP header; You are responsible for writing this. More...

uint16_t	checksum_ip (struct sr_ip_hdr *hdr)
	Helper function which computes and sets the checksum on an IP header.

uint16_t	checksum (uint16_t *buf, unsigned len)
	Helper function which computes the checksum over the specified length of the given buffer.

void	icmp_send (struct sr_instance router, uint32_t dst, uint32_t src, uint8_t ip_packet, unsigned len, uint8_t type, uint8_t code, uint16_t id, uint16_t seq)
	Creates an ICMP header and encapsulates the given buffer (if any); You are responsible for writing this. More...

struct sr_if *	router_lookup_interface_via_ip (struct sr_instance *sr, uint32_t dst)

int	ip_send_packet (struct sr_instance router, uint32_t dst, uint8_t proto_id, uint8_t payload, unsigned len)
	Wrapper function for ip_send_packet_from when the outbound address & interface are not known; This is already implemented for you. More...

int	ip_to_me (struct sr_instance *sr, uint32_t dst)
	Helper function to determine whether an IP packet is destined for any of the router's interfaces' addresses. More...

void	icmp_handle_packet (struct sr_instance router, uint8_t ip_packet, unsigned len)
	Handles all incoming packets with an ICMP header; This is already implemented for you.

uint16_t	checksum_icmp (sr_icmp_hdr_t *icmp_hdr, unsigned total_len)
	Computes and sets the checksum on an ICMP header.

int	ip_send_packet_from (struct sr_instance router, uint32_t dst, uint32_t src, uint8_t proto_id, uint8_t buf, unsigned len)
	Creates an IP header and encapsulates the given buffer; You are responsible for writing this. More...

struct sr_rt *	rtable_find_route (struct sr_instance *sr, uint32_t dst_ip)
	Given a destination IP address, looks up the routing table entry for the next hop; This is already implemented for you.

int	router_send_ethernet_frame (struct sr_instance router, uint32_t dst_ip, uint16_t type, uint8_t payload, unsigned len)
	Searches the routing table to find the correct interface on which to send the payload based on the destination IP, then queues the packet; This is already implemented for you. More...

int	router_queue_ethernet_frame (struct sr_instance sr, struct sr_rt rti, struct sr_if intf, uint16_t type, uint8_t payload, unsigned payload_len)
	Constructs an ethernet packet to the correct MAC address - if this exists in the cache the packet can be sent immediately, otherwise it must be queued while the ARP cache resolves the next hop IP address's MAC address; You are responsible for writing this. More...

int	handle_arpreq (struct sr_instance sr, struct sr_arpreq req)
	Handles sending ARP requests to get IP/MAC mappings; You are responsible for writing this. More...

Detailed Description

The set of functions which accept, queue, and send packets; Most of your work will go here.

Function Documentation

◆ ether_to_me()

int ether_to_me	(	unsigned char *	my_address,
		unsigned char *	addr_s
	)

Determine if an ethernet frame is addressed to a given interface's MAC address.

Parameters

my_address	the router interface's MAC address
addr_s	the MAC address we would like to check against

Returns: Nonzero (true) if the addresses match, or the second argument is the broadcast address. Zero (false) otherwise.

◆ handle_arp()

int handle_arp	(	struct sr_instance *	sr,
		uint8_t *	packet,
		unsigned int	len,
		char *	interface
	)

Handles all incoming packets with an ARP header; You are responsible for writing this.

Parameters

sr	the router instance
packet	the raw ARP packet
len	the size of the raw ARP packet
interface	the name of the interface which the packet arrived on

◆ handle_arpreq()

int handle_arpreq	(	struct sr_instance *	sr,
		struct sr_arpreq *	req
	)

Handles sending ARP requests to get IP/MAC mappings; You are responsible for writing this.

Parameters

sr	the router instance
req	the ARP request to be resolved

◆ handle_ip()

int handle_ip	(	struct sr_instance *	sr,
		uint8_t *	packet,
		unsigned int	len,
		char *	interface
	)

Handles all incoming packets with an IP header; You are responsible for writing this.

Parameters

sr	the router instance
packet	the raw IP packet
len	the size of the raw IP packet
interface	the name of the interface which the packet arrived on

◆ icmp_send()

void icmp_send	(	struct sr_instance *	router,
		uint32_t	dst,
		uint32_t	src,
		uint8_t *	ip_packet,
		unsigned	len,
		uint8_t	type,
		uint8_t	code,
		uint16_t	id,
		uint16_t	seq
	)

Creates an ICMP header and encapsulates the given buffer (if any); You are responsible for writing this.

Parameters

router	the router instance
dst	the destination address
src	the source address
ip_packet	the IP packet which triggered the creation of this ICMP packet, if any
len	the length of the IP packet, if any
type	type of ICMP packet to be created
code	code of ICMP packet to be created
id	id of the ICMP packet
seq	sequence number of the ICMP packet

◆ ip_send_packet()

int ip_send_packet	(	struct sr_instance *	router,
		uint32_t	dst,
		uint8_t	proto,
		uint8_t *	payload,
		unsigned	len
	)

Wrapper function for ip_send_packet_from when the outbound address & interface are not known; This is already implemented for you.

Parameters

router	the router instance
dst	the destination address
proto	the protocol of the encapsulated buffer
payload	buffer to encapsulate with IP header
len	size of the buffer

◆ ip_send_packet_from()

int ip_send_packet_from	(	struct sr_instance *	,
		uint32_t	dst,
		uint32_t	src,
		uint8_t	proto,
		uint8_t *	buf,
		unsigned	len
	)

Creates an IP header and encapsulates the given buffer; You are responsible for writing this.

Parameters

sr_instance	the router instance
dst	the destination address
src	the source address
proto	the protocol of the encapsulated buffer
buf	buffer to encapsulate with IP header
len	size of the buffer

◆ ip_to_me()

int ip_to_me	(	struct sr_instance *	,
		uint32_t
	)

Helper function to determine whether an IP packet is destined for any of the router's interfaces' addresses.

Parameters

sr_instance	the router instance
uint32_t	the destination address in question

◆ router_queue_ethernet_frame()

int router_queue_ethernet_frame	(	struct sr_instance *	router,
		struct sr_rt *	rti,
		struct sr_if *	intf,
		uint16_t	type,
		uint8_t *	payload,
		unsigned	payload_len
	)

Constructs an ethernet packet to the correct MAC address - if this exists in the cache the packet can be sent immediately, otherwise it must be queued while the ARP cache resolves the next hop IP address's MAC address; You are responsible for writing this.

Parameters

router	the router instance
rti	the routing table
intf	the outgoing interface
type	the type of ethernet traffic
payload	the packet to be encapsulated in an ethernet frame
payload_len	the size of the payload

◆ router_send_ethernet_frame()

int router_send_ethernet_frame	(	struct sr_instance *	router,
		uint32_t	dst_ip,
		uint16_t	type,
		uint8_t *	payload,
		unsigned	len
	)

Searches the routing table to find the correct interface on which to send the payload based on the destination IP, then queues the packet; This is already implemented for you.

Parameters

router	the router instance
dst_ip	the destination IP address
type	the type of ethernet traffic
payload	the packet to be encapsulated in an ethernet frame
len	the size of the payload

◆ sr_handlepacket()

void sr_handlepacket	(	struct sr_instance *	,
		uint8_t *	,
		unsigned	int,
		char *
	)

Called whenever an incoming packet is received; You are responsible for writing this.

This function checks that a received packet is well structured, decapsulates it, and then calls another handler based on the packet type.

Functions

Detailed Description

Function Documentation

◆ ether_to_me()

◆ handle_arp()

◆ handle_arpreq()

◆ handle_ip()

◆ icmp_send()

◆ ip_send_packet()

◆ ip_send_packet_from()

◆ ip_to_me()

◆ router_queue_ethernet_frame()

◆ router_send_ethernet_frame()

◆ sr_handlepacket()