netio.c File Reference

functions for network I/O More...

#include <netio.h>
#include <log.h>
#include <ssl_timeoutio.h>
#include <tls.h>
#include <assert.h>
#include <errno.h>
#include <poll.h>
#include <string.h>
#include <unistd.h>

Macros
#define	_GNU_SOURCE   /* to get POLLRDHUP if possible */
#define	POLL_IN_OR_ERROR   POLLIN
#define	DEBUG_IN(l)   {}
#define	DEBUG_OUT(s, l)   {}

Functions
static void	get_from_inbuffer (char *dest, const size_t len, const size_t droplen)
static size_t	readinput (char *buffer, const size_t len, const int fatal)
static const char *	find_eol (const char *buffer, const size_t buflen, int *valid)
static void	loop_long (int has_cr)
int	net_read (const int fatal)
	read one line from the network More...
int	netnwrite (const char *s, const size_t l)
int	net_writen (const char *const *s)
int	net_write_multiline (const char *const *s)
size_t	net_readbin (size_t num, char *buf)
size_t	net_readline (size_t num, char *buf)
int	data_pending (void)
	check if there is data ready to be read without blocking More...

Variables
static char	lineinbuf [1002]
struct string	linein
static char	lineinn [sizeof(lineinbuf)]
static size_t	linenlen
time_t	timeout

Detailed Description

functions for network I/O

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.

static const char* find_eol ( const char *  buffer, const size_t  buflen, int *  valid  )

static

detect the end of the first line in the given buffer

Parameters

buffer	input buffer to check
buflen	amount of data in buffer
valid	a flag is stored here if the line is valid

Returns

the first character after the line end

Return values

NULL	buffer does neither contain CR nor LF

If the buffer begins with a sequence of characters that contains a stray CR or LF a pointer one character behind this is returned and valid is set to 0. If the buffer begins with a valid line ending in CRLF a pointer behind the LF is returned. If neither CR nor LF is found NULL is returned.

static void get_from_inbuffer ( char *  dest, const size_t  len, const size_t  droplen  )

static

read the first characters of lineinn

Parameters

dest	destination buffer or NULL to simply drop the data
len	characters to copy
droplen	additional characters to drop (usually 2 to drop CRLF)

Move the rest of the buffer content forward (if any).

static void loop_long ( int  has_cr )

static

read input until a line with a valid length is in buffer

Parameters

has_cr

if the previous buffer ended with CR

This function will set errno to the proper error code before returning.

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

static size_t readinput ( char *  buffer, const size_t  len, const int  fatal  )

static

read characters from (network) input

Parameters

buffer	buffer to put the data in
len	maximum length of data to read (one char less is read, the last one is set to '\0')
fatal	if connection errors should lead to program termination

Returns

number of bytes read

Return values

-1	on error (errno is set)

Variable Documentation

struct string linein

Initial value:

= {
        .s = lineinbuf
}

char lineinbuf[1002]

static

buffer for the line to read: max 1000 chars including CRLF, leading extra '.', closing '\0'

char lineinn[sizeof(lineinbuf)]

static

if more than one line was in linein the rest is stored here

size_t linenlen

static

length of the lineinn

time_t timeout

how long to wait for data