Global header file for all layers, containging all necessary libraries and defining global preprocessor directives such as the chunk size. More...

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>

Classes
struct	student

Macros
#define	MAX_CHUNK_SIZE 16 /* sets chunk for all layers as 16 bytes */

#define	LAYER 0 /* 1-5 for testing. 0 for normal use */

Functions
void	print_title (int num, FILE mode, char title)
	Used for testing, prints a pretty formatted title a specified file. More...

int	my_pow (int x, int n)
	Used fast exponentiation to calculate powers. More...

int	bin_exp (int num)
	Lazy Binary number calculation. More...

void	itozstring (char *o_buff, int num, int len)
	Converts a integer to a string. More...

int	stonum (char *i_buff, int len)
	Converts 0 padded strings to an integer. More...

double	stodoub (char *i_buff)
	Converts a string formatted as a double to an actual double. More...

int	layer1_read (char *b)
	Sample layer1_read just calls read on stdin. More...

int	layer1_write (char b)
	Sample layer1_write just calls write to stdout. More...

int	layer2_write (char *chunk, int len)
	Sends a chunk that consists of the sequence of bytes starting at the address specified by the first parameter (chunk) with length len. More...

int	layer2_read (char *chunk, int max)
	Reads a chunk and stores the incoming bytes in the buffer starting at the address specified by the first parameter (chunk). More...

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...

int	layer4_write (char *msg, int len)
	Computes a checksum of the message and sends it to layer4_read. More...

int	layer4_read (char *msg, int max)
	Reads a message into memory starting at the address specified by msg. More...

int	layer5_write (student *stu)

int	layer5_read (student *stu)
	Dynamically allocate memory of the appropriate size for the firstname and lastname fields. More...

Detailed Description

Global header file for all layers, containging all necessary libraries and defining global preprocessor directives such as the chunk size.

Additionally preprocessor directives are used to limit the scope of testing various layers. Set layer from 1-5 for testing and 0 for normal use.

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

Macro Definition Documentation

#define MAX_CHUNK_SIZE 16 /* sets chunk for all layers as 16 bytes */

A chunk :: a sequence of bytes whose length is no greater than 16 bytes

Each of the bytes in a chunk can have any value, including binary data and the '\0' character; only restriction is there are no more than 16 bytes.
Note that it is also valid to send/receive a chunk of size 0.

Function Documentation

int bin_exp ( int num )

Lazy Binary number calculation.

Parameters

[in] num The number to calculate binary of, i.e. 4 = 2^3 = 8

Returns: 2^num

void itozstring	(	char *	o_buff,
		int	num,
		int	len
	)

Converts a integer to a string.

Parameters

[out]	o_buff	The correctly sized buffer to store the string in.
[in]	num	The number to convert to a string.
[in]	len	The size of the zero padded string to produce.

Returns

int layer1_read ( char * b )

Sample layer1_read just calls read on stdin.

Parameters

[in] b

Returns: The number of bytes read: 1 if everything goes well. -1 if there was an error.

int layer1_write ( char b )

Sample layer1_write just calls write to stdout.

Parameters

[in] b

Returns: The number of bytes written: 1 if everything goes well. -1 if there was an error.

A chunk :: a sequence of bytes whose length is no greater than 16 bytes

Each of the bytes in a chunk can have any value, including binary data and the '\0' character; only restriction is there are no more than 16 bytes.
Note that it is also valid to send/receive a chunk of size 0. TODO List
Add check function that checks max length vs actual length (const)

Parameters

[in] b

Returns: The number of bytes written: 1 if everything goes well. -1 if there was an error.

int layer2_read	(	char *	chunk,
		int	max
	)

Reads a chunk and stores the incoming bytes in the buffer starting at the address specified by the first parameter (chunk).

Warning: Make sure that your layer2_read() does not allow the sender to overflow the buffer! And it's not enough to recognize when this has happened and return an error; you must not store anything beyond the max location of chunk.

Parameters

[in]	chunk	A sequence of bytes whose length is no greater than 16 bytes as defined by MAX_CHUNK_SIZE which can contain any type of data.
[in]	max	No more than max bytes will be put into chunk, so max limits the size of the chunk read.

Returns: Upon successfully receiving a chunk, the size of the chunk in bytes is returned.

int layer2_write	(	char *	chunk,
		int	len
	)

Sends a chunk that consists of the sequence of bytes starting at the address specified by the first parameter (chunk) with length len.

Warning: all errors that can be detected here must be handled here including valid values of len and the return value of layer1_write()

Parameters

[in]	chunk	The data to write using layer 1 protocols.
[in]	len	The size of the chunk to write.

Returns: len on success, -1 on error

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.

int layer4_read	(	char *	msg,
		int	max
	)

Reads a message into memory starting at the address specified by msg.

Parameters

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

Returns: -1 if max size is incorrect or if there is a transmission error. The size of the message in bytes is returned otherwise.

int layer4_write	(	char *	msg,
		int	len
	)

Computes a checksum of the message and sends it to layer4_read.

Parameters

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

Returns: The number of Bytes sent.

int layer5_read ( student * stu )

Dynamically allocate memory of the appropriate size for the firstname and lastname fields.

Warning: It is the responsibility of the caller to free this memory.

Parameters

[out] stu The student struct to read onto.

Returns: The return value is 1 on success, or -1 on error.

int my_pow	(	int	x,
		int	n
	)

Used fast exponentiation to calculate powers.

Parameters

[in]	x	The base.
[in]	y	The power.

Returns: x^y.

void print_title	(	int	num,
		FILE *	mode,
		char *	title
	)

Used for testing, prints a pretty formatted title a specified file.

Parameters

[in]	num	0 for first header, 1 for any other header
[in]	mode	The file to write to
[in]	title	The string to print in the title

Returns: void

double stodoub ( char * i_buff )

Converts a string formatted as a double to an actual double.

Parameters

[in] i_buff The string to convert.

Returns: The string result as a double.

int stonum	(	char *	i_buff,
		int	len
	)

Converts 0 padded strings to an integer.

Parameters

[in]	i_buff	The input buffer containing the string to decode.
[in]	size	The size of the input stirng.

Returns: The number as an integer.

Classes

Macros

Functions

Detailed Description

Macro Definition Documentation

Function Documentation