netio.h File Reference

functions for network I/O More...

#include "sstring.h"
#include <string.h>
#include <sys/types.h>
#include <time.h>

Go to the source code of this file.

Enumerations
enum	conn_shutdown_type { shutdown_clean, shutdown_abort }

Functions
int	net_read (const int fatal)
	read one line from the network More...
int	net_writen (const char *const *)
int	net_write_multiline (const char *const *)
static int	netwrite (const char *)
int	netnwrite (const char *, const size_t)
size_t	net_readbin (size_t, char *)
size_t	net_readline (size_t, char *)
int	data_pending (void)
	check if there is data ready to be read without blocking More...
void	net_conn_shutdown (const enum conn_shutdown_type sd_type)
	shutdown the connection and end the program More...

Variables
struct string	linein
time_t	timeout
int	socketd

Detailed Description

functions for network I/O

Enumeration Type Documentation

enum conn_shutdown_type

Enumerator
shutdown_clean	do a normal shutdown and notify the partner about the shutdown
shutdown_abort	do hard abort of connection

Function Documentation

int data_pending

(

void

)

check if there is data ready to be read without blocking

Returns

if there is data available

Return values

0	if no data
1	if data
<0	error code

This will return -ECONNRESET if the connection has been closed by the remote end.

void net_conn_shutdown

(

const enum conn_shutdown_type

sd_type

)

shutdown the connection and end the program

Parameters

sd_type

specifies the way the shutdown should be performed

This is a forward declaration only, every program has to implement this function in a way that matches how it works.

A shutdown_clean shutdown is e.g. sending QUIT to the server and waiting for it's reply. A shutdown with shutdown_abort is e.g. hard dropping of the connection if the client sends spam and has a broken SMTP engine that does not react to error codes.

Calling this function even before the connection was established is fine.

int net_read

(

const int

fatal

)

read one line from the network

Parameters

fatal

if connection errors should lead to program termination

Return values

0	on success
-1	on error (errno is set)

does not return on timeout, program will be cancelled

size_t net_readbin	(	size_t	num,
		char *	buf
	)

read a given number of bytes from network as binary data (i.e. without any mangling)

Parameters

num	number of bytes to read
buf	buffer to store data (must have enough space for (num + 1) bytes)

Returns

number of bytes read

Return values

-1

on error

size_t net_readline	(	size_t	num,
		char *	buf
	)

read up to a given number of bytes from network but stop at the first CRLF

Parameters

num	number of bytes to read, must be < 1002 so everything behind the CRLF can be copied back to lineinn
buf	buffer to store data (must have enough space)

Returns

number of bytes read

Return values

-1

on error

The trailing CRLF sequence is kept in the buffer. This function will return an error if it detects a bare CR or LF in the middle of the input data, but it cannot detect if the CR goes in one call and LF in the next, so it will allow the output to be just LF or to end in CR.

int net_write_multiline

(

const char *const *

s

)

write multiple lines to the network

Parameters

s	array of strings to send

Return values

0	on success
-1	on error (errno is set)

This combines all given strings into one buffer and send them out to the network. This allows the underlying network stack to use the least sensible number of packets, reducing network latency. If memory allocation fails for the intermediate buffer the lines may be send in smaller chunks, which is less efficient but is no other loss in functionality.

Does not return on timeout, program will be cancelled.

If one part or multiple consecutive parts covers a whole SMTP line this line must conform to the SMTP line length limit (512 bytes).

int net_writen

(

const char *const *

s

)

write one line to the network, fold if needed

Parameters

s	array of strings to send

Return values

0	on success
-1	on error (errno is set)

does not return on timeout, program will be cancelled

Warning

s[0] must be short enough to fit completely into the buffer

s[0] must contain the whole status code as well as the following space (' ') or hyphen ('-')

every s[] must not have a sequence longer then 506 characters without a space (' ') in them

int netnwrite	(	const char *	s,
		const size_t	l
	)

write one line to the network

Parameters

s	line to be written (nothing else it written so it should contain CRLF)
l	length of s

Return values

0	on success
-1	on error (errno is set)

does not return on timeout, program will be cancelled

Variable Documentation

int socketd

the descriptor where messages to network are written to

time_t timeout

how long to wait for data