layer3.c File Reference

Layer 3 provides the capability to send and receive messages, where a message is defined as any sequence of bytes. More...

#include "layer.h"

Functions
int	layer3_write (char *msg, int len)
	Sends a message. More...
int	layer3_read (char *msg, int max)
	reads a message and stores it in memory starting at the address specified by msg More...

Detailed Description

Layer 3 provides the capability to send and receive messages, where a message is defined as any sequence of bytes.

More specifically, there is no length limitation at layer 3, so a sender can ask layer 3 to send any size message.

Peer-to-peer and Interface Protocols Using C

Author

Nicholas Guthrie guthr.nosp@m.n@rp.nosp@m.i.edu http//nickguthrie.com January 30, 2014

Compile with: gcc -c layer3.c -o ../build/layer3.o

Function Documentation

int layer3_read	(	char *	msg,
		int	max
	)

reads a message and stores it in memory starting at the address specified by msg

Parameters

[in]	msg	Where the message that is read is stored.
[in]	max	No more than max bytes will be put into memory, so max must limit the size of the message read.

Returns

The size of the message received or -1 on error.

If a message is received by layer3_read() that would require more than max bytes, layer3_read() must return -1 (indicating an error).

int layer3_write	(	char *	msg,
		int	len
	)

Sends a message.

Parameters

[in]	msg	A message of any length to send.
[in]	len	The size of the message to send.

Returns

The number of bytes (of the message) sent on success (should be len) or -1 on error.