Serial Line IP (SLIP) protocol

The SLIP protocol is a very simple way to transmit IP packets over a serial line.

It does not provide any framing or error control, and is therefore not very widely used today.

This SLIP implementation requires two functions for accessing the serial device: slipdev_char_poll() and slipdev_char_put(). These must be implemented specifically for the system on which the SLIP protocol is to be run.

Files
file	slipdev.c
	SLIP protocol implementation.
file	slipdev.h
	SLIP header file.

Macros
#define	SLIP_END   0300
#define	SLIP_ESC   0333
#define	SLIP_ESC_END   0334
#define	SLIP_ESC_ESC   0335

Functions
uint8_t	slipdev_char_poll (uint8_t *c)
	Poll the serial device for a character. More...
void	slipdev_char_put (uint8_t c)
	Put a character on the serial device. More...
void	slipdev_init (void)
	Initialize the SLIP module. More...
uint16_t	slipdev_poll (void)
	Poll the SLIP device for an available packet. More...
uint8_t	slipdev_send (void)
	Send the packet in the uip_buf and uip_appdata buffers using the SLIP protocol. More...

Variables
static uint8_t	lastc
static uint16_t	len
static uint8_t	slip_buf [UIP_BUFSIZE]
static uint16_t	tmplen

#define SLIP_END   0300

Referenced by slipdev_poll(), and slipdev_send().

#define SLIP_ESC   0333

Referenced by slipdev_poll(), and slipdev_send().

#define SLIP_ESC_END   0334

Referenced by slipdev_poll(), and slipdev_send().

#define SLIP_ESC_ESC   0335

Referenced by slipdev_poll(), and slipdev_send().

uint8_t slipdev_char_poll

(

uint8_t *

c

)

Poll the serial device for a character.

This function is used by the SLIP implementation to poll the serial device for a character. It must be implemented specifically for the system on which the SLIP implementation is to be run.

The function should return immediately regardless if a character is available or not. If a character is available it should be placed at the memory location pointed to by the pointer supplied by the argument c.

Parameters

c	A pointer to a byte that is filled in by the function with the received character, if available.

Return values

0	If no character is available.
Non-zero	If a character is available.

Referenced by slipdev_poll().

void slipdev_char_put

(

uint8_t

c

)

Put a character on the serial device.

This function is used by the SLIP implementation to put a character on the serial device. It must be implemented specifically for the system on which the SLIP implementation is to be run.

Parameters

c	The character to be put on the serial device.

Referenced by slipdev_send().

void slipdev_init

(

void

)

Initialize the SLIP module.

This function does not initialize the underlying RS232 device, but only the SLIP part.

References lastc, and len.

uint16_t slipdev_poll

(

void

)

Poll the SLIP device for an available packet.

This function will poll the SLIP device to see if a packet is available. It uses a buffer in which all avaliable bytes from the RS232 interface are read into. When a full packet has been read into the buffer, the packet is copied into the uip_buf buffer and the length of the packet is returned.

Returns

The length of the packet placed in the uip_buf buffer, or zero if no packet is available.

References c, lastc, len, slip_buf, SLIP_END, SLIP_ESC, SLIP_ESC_END, SLIP_ESC_ESC, slipdev_char_poll(), tmplen, uip_buf, UIP_BUFSIZE, and UIP_LLH_LEN.

uint8_t slipdev_send

(

void

)

Send the packet in the uip_buf and uip_appdata buffers using the SLIP protocol.

The first 40 bytes of the packet (the IP and TCP headers) are read from the uip_buf buffer, and the following bytes (the application data) are read from the uip_appdata buffer.

Returns

This function will always return 0.

References c, i, SLIP_END, SLIP_ESC, SLIP_ESC_END, SLIP_ESC_ESC, slipdev_char_put(), uip_appdata, uip_buf, uip_len, UIP_LLH_LEN, and UIP_TCPIP_HLEN.

uint8_t lastc

static

Referenced by slipdev_init(), and slipdev_poll().

uint16_t len

static

Referenced by _read(), _write(), cbcmac_calc(), cbcmac_verify(), crc16_data(), create(), dao_input(), decode_name(), dio_input(), get_match_length(), handle_incoming_rreq(), mdns_lookup(), mdns_query(), newdata(), packetbuf_compact(), packetbuf_copyfrom(), packetbuf_reference(), packetbuf_set_datalen(), parse(), parse_options(), PROCESS_THREAD(), PT_THREAD(), read(), remove_trailing_dots(), rf233_read(), rpl_set_prefix(), send_one_packet(), send_packet(), send_rreq(), senddata(), sensors_find(), slip_poll_handler(), slip_write(), slipdev_init(), slipdev_poll(), tcp_socket_send(), uip_packetqueue_set_buflen(), uip_udp_packet_send(), uiplib_ip6addrconv(), and uncompress_hdr_hc06().

uint8_t slip_buf[UIP_BUFSIZE]

static

Referenced by slipdev_poll().

uint16_t tmplen

static

Referenced by slipdev_poll().