The uIP IPv6 stack provides new Internet communication abilities to Contiki. More...

Modules
	RPL implementation ContikiRPL (RFC 6550).

	IPv6 Neighbor cache (link-layer/IPv6 address mapping)
	Data structure and methods for IPv6 Neighbor Cache (RFC 4861, section 5.1)

	Routing

	Network interface and stateless autoconfiguration (RFC 4862)

	Neighbor discovery (RFC 4861)

Files
file	rpl-ext-header.c
	Management of extension headers for ContikiRPL.

file	rpl-icmp6.c
	ICMP6 I/O for RPL control messages.

file	rpl-mrhof.c
	The Minimum Rank with Hysteresis Objective Function (MRHOF)

file	rpl-of0.c
	An implementation of RPL's objective function 0.

file	rpl-timers.c
	RPL timer management.

file	uip-ds6.c
	IPv6 data structures handling functions.

file	uip-icmp6.c
	ICMPv6 echo request and error messages (RFC 4443)

file	uip-icmp6.h
	ICMPv6 echo request and error messages (RFC 4443)

file	uip6.c
	The uIP TCP/IPv6 stack code.

Data Structures
struct	uip_icmp6_error
	ICMPv6 Error message constant part. More...

Macros
#define	UIP_ICMP6_ECHO_REQUEST_LEN 4
	Echo Request constant part length.

#define	UIP_ICMP6_ERROR_LEN 4
	ICMPv6 Error message constant part length.

#define	UIP_ND6_OPT_HDR_BUF ((uip_nd6_opt_hdr *)&uip_buf[uip_l2_l3_icmp_hdr_len + nd6_opt_offset])
	Pointer to ND option.

Typedefs
typedef struct uip_icmp6_error	uip_icmp6_error
	ICMPv6 Error message constant part.

Functions
enum rpl_mode	rpl_get_mode (void)
	Get the RPL mode. More...

enum rpl_mode	rpl_set_mode (enum rpl_mode m)
	Set the RPL mode. More...

void	uip_ds6_neighbors_init (void)
	Initialize neighbor cache. More...

uip_ds6_nbr_t *	uip_ds6_nbr_add (const uip_ipaddr_t ipaddr, const uip_lladdr_t lladdr, uint8_t isrouter, uint8_t state)
	Adds a neighbor to the neighbor cache. More...

void	uip_ds6_nbr_rm (uip_ds6_nbr_t *nbr)
	Removes entry from neighbor cache.

const uip_ipaddr_t *	uip_ds6_nbr_get_ipaddr (const uip_ds6_nbr_t *nbr)
	Returns IP address of neighbor.

const uip_lladdr_t *	uip_ds6_nbr_get_ll (const uip_ds6_nbr_t *nbr)
	Returns link-local address of neighbor.

int	uip_ds6_nbr_num (void)
	?

uip_ds6_nbr_t *	uip_ds6_nbr_lookup (const uip_ipaddr_t *ipaddr)
	Lookup if a neighbor cache entry for given IP address exists. More...

uip_ds6_nbr_t *	uip_ds6_nbr_ll_lookup (const uip_lladdr_t *lladdr)
	Lookup if a neighbor cache entry for given link-layer address exists. More...

uip_ipaddr_t *	uip_ds6_nbr_ipaddr_from_lladdr (const uip_lladdr_t *lladdr)
	Returns IP address associated with link-local address, based on neighbor cache entry. More...

const uip_lladdr_t *	uip_ds6_nbr_lladdr_from_ipaddr (const uip_ipaddr_t *ipaddr)
	Returns link-layer address associated with IP address, based on neighbor cache entry. More...

void	uip_ds6_link_neighbor_callback (int status, int numtx)
	?

void	uip_ds6_neighbor_periodic (void)
	?

uip_ds6_nbr_t *	uip_ds6_get_least_lifetime_neighbor (void)
	This searches inside the neighbor table for the neighbor that is about to expire the next. More...

void	uip_ds6_init (void)
	Initialize data structures.

void	uip_ds6_periodic (void)
	Periodic processing of data structures.

uint8_t	uip_ds6_list_loop (uip_ds6_element_t list, uint8_t size, uint16_t elementsize, uip_ipaddr_t ipaddr, uint8_t ipaddrlen, uip_ds6_element_t **out_element)
	Generic loop routine on an abstract data structure, which generalizes all data structures used in DS6.

void	uip_ds6_select_src (uip_ipaddr_t src, uip_ipaddr_t dst)
	Source address selection, see RFC 3484.

void	uip_ds6_set_addr_iid (uip_ipaddr_t ipaddr, uip_lladdr_t lladdr)
	set the last 64 bits of an IP address based on the MAC address

uint8_t	get_match_length (uip_ipaddr_t src, uip_ipaddr_t dst)
	Get the number of matching bits of two addresses.

void	uip_ds6_send_rs (void)
	Send periodic RS to find router.

uint32_t	uip_ds6_compute_reachable_time (void)
	Compute the reachable time based on base reachable time, see RFC 4861.

uint16_t	uip_chksum (uint16_t *data, uint16_t len)
	Calculate the Internet checksum over a buffer. More...

uint16_t	uip_ipchksum (void)
	Calculate the IP header checksum of the packet header in uip_buf. More...

uint16_t	uip_icmp6chksum (void)
	Calculate the ICMP checksum of the packet in uip_buf. More...

void	uip_init (void)
	uIP initialization function. More...

void	uip_process (uint8_t flag)
	process the options within a hop by hop or destination option header More...

uint16_t	uip_htons (uint16_t val)
	Convert a 16-bit quantity from host byte order to network byte order. More...

void	uip_send (const void *data, int len)
	Send data on the current connection. More...

Variables
struct etimer	uip_ds6_timer_rs
	Timer for maintenance of data structures.

"DS6" Data structures
number of rs already sent
uip_ds6_netif_t	uip_ds6_if

uip_ds6_prefix_t	uip_ds6_prefix_list [UIP_DS6_PREFIX_NB]
	The single interface.

uint8_t	uip_ds6_addr_size
	Prefix list.

uint8_t	uip_ds6_netif_addr_list_offset

ICMPv6 message types
#define	ICMP6_DST_UNREACH 1
	dest unreachable

#define	ICMP6_PACKET_TOO_BIG 2
	packet too big

#define	ICMP6_TIME_EXCEEDED 3
	time exceeded

#define	ICMP6_PARAM_PROB 4
	ip6 header bad

#define	ICMP6_ECHO_REQUEST 128
	Echo request.

#define	ICMP6_ECHO_REPLY 129
	Echo reply.

#define	ICMP6_RS 133
	Router Solicitation.

#define	ICMP6_RA 134
	Router Advertisement.

#define	ICMP6_NS 135
	Neighbor Solicitation.

#define	ICMP6_NA 136
	Neighbor advertisement.

#define	ICMP6_REDIRECT 137
	Redirect.

#define	ICMP6_RPL 155
	RPL.

#define	ICMP6_PRIV_EXP_100 100
	Private Experimentation.

#define	ICMP6_PRIV_EXP_101 101
	Private Experimentation.

#define	ICMP6_PRIV_EXP_200 200
	Private Experimentation.

#define	ICMP6_PRIV_EXP_201 201
	Private Experimentation.

#define	ICMP6_ROLL_TM ICMP6_PRIV_EXP_200
	ROLL Trickle Multicast.

ICMPv6 Destination Unreachable message codes
#define	ICMP6_DST_UNREACH_NOROUTE 0
	no route to destination

#define	ICMP6_DST_UNREACH_ADMIN 1
	administratively prohibited

#define	ICMP6_DST_UNREACH_NOTNEIGHBOR 2
	not a neighbor(obsolete)

#define	ICMP6_DST_UNREACH_BEYONDSCOPE 2
	beyond scope of source address

#define	ICMP6_DST_UNREACH_ADDR 3
	address unreachable

#define	ICMP6_DST_UNREACH_NOPORT 4
	port unreachable

ICMPv6 Time Exceeded message codes
#define	ICMP6_TIME_EXCEED_TRANSIT 0
	ttl==0 in transit

#define	ICMP6_TIME_EXCEED_REASSEMBLY 1
	ttl==0 in reass

ICMPv6 Parameter Problem message codes
#define	ICMP6_PARAMPROB_HEADER 0
	erroneous header field

#define	ICMP6_PARAMPROB_NEXTHEADER 1
	unrecognized next header

#define	ICMP6_PARAMPROB_OPTION 2
	unrecognized option

ICMPv6 RFC4443 Message processing and sending
typedef void(*	uip_icmp6_echo_reply_callback_t )(uip_ipaddr_t source, uint8_t ttl, uint8_t data, uint16_t datalen)

void	uip_icmp6_echo_request_input (void)
	\ brief Process an echo request More...

void	uip_icmp6_error_output (uint8_t type, uint8_t code, uint32_t param)
	Send an icmpv6 error message. More...

void	uip_icmp6_send (const uip_ipaddr_t *dest, int type, int code, int payload_len)
	Send an icmpv6 message. More...

void	uip_icmp6_echo_reply_input (void)
	\ brief Process an echo reply More...

void	uip_icmp6_echo_reply_callback_add (struct uip_icmp6_echo_reply_notification *n, uip_icmp6_echo_reply_callback_t c)
	Add a callback function for ping replies. More...

void	uip_icmp6_echo_reply_callback_rm (struct uip_icmp6_echo_reply_notification *n)
	Remove a callback function for ping replies. More...

Pointers to the header structures.
All pointers except UIP_IP_BUF depend on uip_ext_len, which at packet reception, is the total length of the extension headers. The pointer to ND6 options header also depends on nd6_opt_offset, which we set in each function. Care should be taken when manipulating these buffers about the value of these length variables
#define	UIP_IP_BUF ((struct uip_ip_hdr *)&uip_buf[UIP_LLH_LEN])
	Pointer to IP header.

#define	UIP_ICMP_BUF ((struct uip_icmp_hdr *)&uip_buf[uip_l2_l3_hdr_len])
	Pointer to ICMP header.

#define	UIP_ND6_RS_BUF ((uip_nd6_rs *)&uip_buf[uip_l2_l3_icmp_hdr_len])

#define	UIP_ND6_RA_BUF ((uip_nd6_ra *)&uip_buf[uip_l2_l3_icmp_hdr_len])

#define	UIP_ND6_NS_BUF ((uip_nd6_ns *)&uip_buf[uip_l2_l3_icmp_hdr_len])

#define	UIP_ND6_NA_BUF ((uip_nd6_na *)&uip_buf[uip_l2_l3_icmp_hdr_len])

Layer 2 variables
uip_lladdr_t	uip_lladdr = {{0x00,0x06,0x98,0x00,0x02,0x32}}
	Host L2 address.

Layer 3 variables
uint8_t *	uip_next_hdr
	Type of the next header in IPv6 header or extension headers. More...

uint8_t	uip_ext_bitmap = 0
	bitmap we use to record which IPv6 headers we have already seen

uint8_t	uip_ext_len = 0
	length of the extension headers read. More...

uint8_t	uip_ext_opt_offset = 0
	length of the header options read

Buffer defines
#define	FBUF ((struct uip_tcpip_hdr *)&uip_reassbuf[0])

#define	UIP_IP_BUF ((struct uip_ip_hdr *)&uip_buf[UIP_LLH_LEN])

#define	UIP_ICMP_BUF ((struct uip_icmp_hdr *)&uip_buf[uip_l2_l3_hdr_len])

#define	UIP_UDP_BUF ((struct uip_udp_hdr *)&uip_buf[UIP_LLH_LEN + UIP_IPH_LEN])

#define	UIP_TCP_BUF ((struct uip_tcp_hdr *)&uip_buf[UIP_LLH_LEN + UIP_IPH_LEN])

#define	UIP_EXT_BUF ((struct uip_ext_hdr *)&uip_buf[uip_l2_l3_hdr_len])

#define	UIP_ROUTING_BUF ((struct uip_routing_hdr *)&uip_buf[uip_l2_l3_hdr_len])

#define	UIP_FRAG_BUF ((struct uip_frag_hdr *)&uip_buf[uip_l2_l3_hdr_len])

#define	UIP_HBHO_BUF ((struct uip_hbho_hdr *)&uip_buf[uip_l2_l3_hdr_len])

#define	UIP_DESTO_BUF ((struct uip_desto_hdr *)&uip_buf[uip_l2_l3_hdr_len])

#define	UIP_EXT_HDR_OPT_BUF ((struct uip_ext_hdr_opt *)&uip_buf[uip_l2_l3_hdr_len + uip_ext_opt_offset])

#define	UIP_EXT_HDR_OPT_PADN_BUF ((struct uip_ext_hdr_opt_padn *)&uip_buf[uip_l2_l3_hdr_len + uip_ext_opt_offset])

#define	UIP_EXT_HDR_OPT_RPL_BUF ((struct uip_ext_hdr_opt_rpl *)&uip_buf[uip_l2_l3_hdr_len + uip_ext_opt_offset])

#define	UIP_ICMP6_ERROR_BUF ((struct uip_icmp6_error *)&uip_buf[uip_l2_l3_icmp_hdr_len])

Buffer variables
uip_buf_t	uip_aligned_buf
	Packet buffer for incoming and outgoing packets.

void *	uip_appdata
	Pointer to the application data in the packet buffer. More...

void *	uip_sappdata

uint16_t	uip_len
	The length of the packet in the uip_buf buffer. More...

uint16_t	uip_slen

General variables
uint8_t	uip_flags

struct uip_conn *	uip_conn
	Pointer to the current TCP connection. More...

TCP defines
#define	TCP_FIN 0x01

#define	TCP_SYN 0x02

#define	TCP_RST 0x04

#define	TCP_PSH 0x08

#define	TCP_ACK 0x10

#define	TCP_URG 0x20

#define	TCP_CTL 0x3f

#define	TCP_OPT_END 0 /* End of TCP options list */

#define	TCP_OPT_NOOP 1 /* "No-operation" TCP option */

#define	TCP_OPT_MSS 2 /* Maximum segment size TCP option */

#define	TCP_OPT_MSS_LEN 4 /* Length of TCP MSS option. */

Detailed Description

The uIP IPv6 stack provides new Internet communication abilities to Contiki.

This document describes Ipv6 specific features. For features that are common to the IPv4 and IPv6 code please refer to uIP.

Introduction

Ipv6 is to replace IPv4 in a near future. Indeed, to move to a real Internet of Things a larger address space is required. This extended address space (2^128 instead of 2^32) is one of the key features of IPv6 together with its simplified header format, its improved support for extensions and options, and its new QoS and security capabilities.

The uip IPv6 stack implementation targets constrained devices such as sensors. The code size is around 11.5Kbyte and the RAM usage around 1.7Kbyte (see below for more detailed information). Our implementation follows closely RFC 4294 IPv6 Node Requirements whose goal is to allow "IPv6 to function well and interoperate in a large number of situations and deployments".

The implementation currently does not support any router features (it does not forward packets, send RAs...)

IPv6 Protocol Implementation

This section gives a short overview of the different protocols that are part of the uIP IPv6 stack. A complete description can be found in the corresponding IETF standards which are available at http://www.ietf.org/rfc.html.

Note: The #UIP_CONF_IPV6 compilation flag is used to enable IPv6 (and disable IPv4). It is also recommended to set UIP_CONF_IPV6_CHECKS to 1 if one cannot guarantee that the incoming packets are correctly formed.

IPv6 (RFC 2460)

The IP packets are processed in the uip_process function. After a few validity checks on the IPv6 header, the extension headers are processed until an upper layer (ICMPv6, UDP or TCP) header is found. We support 4 extension headers:

Hop-by-Hop Options: this header is used to carry optional information that need to be examined only by a packet's destination node.
Routing: this header is used by an IPv6 source to list one or more intermediate nodes to be "visited" on the way to a packet's destination.
Fragment: this header is used when a large packet is divided into smaller fragments.
Destination Options: this header is used to carry optional information that need be examined only by a packet's destination node The Authentication and ESP headers are not currently supported.

The IPv6 header, extension headers, and options are defined in uip.h.

Although we can receive packets with the extension headers listed above, we do not offer support to send packets with extension headers.

Fragment Reassembly
This part of the code is very similar to the IPv4 fragmentation code. The only difference is that the fragmented packet is not assumed to be a TCP packet. As a result, we use a different timer to time-out reassembly if all fragments have not been received after UIP_REASS_MAXAGE = 60s.

Note: Fragment reassembly is enabled if #UIP_CONF_REASSEMBLY is set to 1.; We can only reassemble packet of at most UIP_LINK_MTU = 1280 bytes as we do not have larger buffers.

Interface and Addressing (RFC 4291, RFC 4861 p.51, RFC 4862 p.10)

An IPv6 address has 128 bits and is defined as follows:

typedef union uip_ip6addr_t {
  uint8_t  u8[16]
  uint16_t u16[8];
} uip_ip6addr_t;

We assume that each node has a single interface of type #uip_netif.

Each interface can have up to #UIP_NETIF_MAX_ADDRESSES unicast IPv6 addresses including its link-local address. It also has a solicited-node multicast address. We assume that the unicast addresses are obtained via stateless address autoconfiguration so that the solicited-node address is the same for all the unicast addresses. Indeed, the solicited-node multicast address is formed by combining the prefix FF02::1:FF00:0/104 and the last 24-bits of the corresponding IPv6 address. When using stateless address autoconfiguration these bits are always equal to the last 24-bits of the link-layer address.

Multicast support

We do not support applications using multicast. Nevertheless, our node should join the all-nodes multicast address, as well as its solicited-node multicast address. Joining the all-nodes multicast address does not require any action. Joining the solicited-node multicast address is done using Multicast Listener Discovery (MLD or MLDv2). More exactly, the node should send a MLD report packet. However this step can be safely skipped and we do so.

Neighbor Discovery (RFC 4861)

"IPv6 nodes on the same link use Neighbor Discovery to discover each other's presence, to determine each other's link-layer addresses, to find routers, and to maintain reachability information about the paths to active neighbors" (citation from the abstract of RFC 4861).

Note: In IPv6 terminology, a link is a communication medium over which nodes can communicate at the link layer, i.e., the layer immediately below IP (e.g.: ethernet, 802.11, etc.). Neighbors are thus nodes attached to the same link.

Neighbor Discovery (ND) replaces ARP in IPv4 but does much more.

Neighbor discovery messages

Neighbor Solicitation (NS)
Sent by a node during duplicate address detection, address resolution or neighbor unreachability detection (see explanations below).
Possible option: Source link-layer address
Neighbor Advertisement (NA)
Sent by a node in response to a NS.
Possible option: Target link-layer address
Router Advertisement (RA)
Sent periodically by routers to advertise their presence together with various link and Internet parameters.
Possible options: Source link-layer address, MTU, Prefix Information
Router Solicitation (RS)
Sent by a host to request routers to generate a RA immediately rather than at their next scheduled time. Received RS are discarded.
Possible option: Source link-layer address
Redirect Message
Not supported

The structures corresponding to the different message headers and options are in uip-nd6.h. The functions used to send / process this messages are also described in uip-nd6.h although the actual code is in uip-nd6-io.c.

Neighbor discovery structures
We use the following neighbor discovery structures (declared in uip-nd6.c):

A neighbor cache with entries of type #uip_nd6_neighbor
A prefix list with entries of type #uip_nd6_prefix
A default router list with entries of type #uip_nd6_defrouter

Each of this structure has its own add, remove and lookup functions. To update an entry in a ND structure, we first do a lookup to obtain a pointer to the entry, we then directly modify the different entry fields.

Neighbor discovery processes

Address resolution
Determine the link-layer address of a neighbor given its IPv6 address.
-> send a NS (done in tcpip_ipv6_output).
Neighbor unreachability detection
Verify that a neighbor is still reachable via a cached link-layer address.
-> send a NS (done in #uip_nd6_periodic).
Next-hop determination
Map an IPv6 destination address into the IPv6 address of the neighbor to which traffic for the destination should be sent.
-> look at on-link prefixes, if the destination is not on-link, choose a default router, else send directly (done in tcpip_ipv6_output).
Router, prefix, and parameter discovery
Update the list of default routers, on-link prefixes, and the network parameters.
-> receive a RA (see #uip_nd6_io_ra_input).

Stateless Address Autoconfiguration (RFC 4862)

RFC 4862 defines two main processes:

Duplicate Address Detection (DAD)
Make sure that an address the node wished to use is not already in use by another node.
-> send a NS (done in #uip_netif_dad)
Address Autoconfiguration
Configure an address for an interface by combining a received prefix and the interface ID (see #uip_netif_addr_add). The interface ID is obtained from the link-layer address using #uip_netif_get_interface_id.
-> Receive a RA with a prefix information option that has the autonomous flag set.

When an interface becomes active, its link-local address is created by combining the FE80::0/64 prefix and the interface ID. DAD is then performed for this link-local address. Available routers are discovered by sending up to #UIP_ND6_MAX_RTR_SOLICITATIONS RS packets. Address autoconfiguration is then performed based on the prefix information received in the RA. The interface initialization is performed in #uip_netif_init.

ICMPv6 (RFC 4443)

We support ICMPv6 Error messages as well as Echo Reply and Echo Request messages. The application used for sending Echo Requests (see ping6.c) is not part of the IP stack.

Note: RFC 4443 stipulates that 'Every ICMPv6 error message MUST include as much of the IPv6 offending (invoking) packet as possible'. In a constrained environment this is not very resource friendly.

The ICMPv6 message headers and constants are defined in uip-icmp6.h.

IPv6 Timers and Processes

The IPv6 stack (like the IPv4 stack) is a Contiki process

PROCESS(tcpip_process, "TCP/IP stack");

In addition to the periodic timer that is used by TCP, five IPv6 specific timers are attached to this process:

The #uip_nd6_timer_periodic is used for periodic checking of the neighbor discovery structures.
The #uip_netif_timer_dad is used to properly paced the Neighbor Solicitation packets sent for Duplicate Address Detection.
The #uip_netif_timer_rs is use to delay the sending of Router Solicitations packets in particular during the router discovery process.
The #uip_netif_timer_periodic is used to periodically check the validity of the addresses attached to the network interface.
The #uip_reass_timer is used to time-out the fragment reassembly process.

Both #uip_nd6_timer_periodic and #uip_netif_timer_periodic run continuously. This could be avoided by using callback timers to handle ND and Netif structures timeouts.

Compile time flags and variables

This section just lists all IPv6 related compile time flags. Each flag function is documented in this page in the appropriate section.

/*Boolean flags*/
UIP_CONF_IPV6        
UIP_CONF_IPV6_CHECKS
UIP_CONF_IPV6_QUEUE_PKT 
UIP_CONF_IPV6_REASSEMBLY        
/*Integer flags*/
UIP_NETIF_MAX_ADDRESSES 
UIP_ND6_MAX_PREFIXES   
UIP_ND6_MAX_NEIGHBORS   
UIP_ND6_MAX_DEFROUTER  

IPv6 Buffers

The IPv6 code uses the same single global buffer as the IPv4 code. This buffer should be large enough to contain one packet of maximum size, i.e., UIP_LINK_MTU = 1280 bytes. When fragment reassembly is enabled an additional buffer of the same size is used.

The only difference with the IPv4 code is the per neighbor buffering that is available when #UIP_CONF_QUEUE_PKT is set to 1. This additional buffering is used to queue one packet per neighbor while performing address resolution for it. This is a very costly feature as it increases the RAM usage by approximately #UIP_ND6_MAX_NEIGHBORS * UIP_LINK_MTU bytes.

IPv6 Code Size

Note: We used Atmel's RAVEN boards with the Atmega1284P MCU (128Kbyte of flash and 16Kbyte of SRAM) to benchmark our code. These numbers are obtained using 'avr-gcc 4.2.2 (WinAVR 20071221)'. Elf is the output format.; The following compilation flags were used:
UIP_CONF_IPV6 1

UIP_CONF_IPV6_CHECKS 1

UIP_CONF_IPV6_QUEUE_PKT 0

UIP_CONF_IPV6_REASSEMBLY 0

UIP_NETIF_MAX_ADDRESSES 3

UIP_ND6_MAX_PREFIXES 3

UIP_ND6_MAX_NEIGHBORS 4

UIP_ND6_MAX_DEFROUTER 2

The total IPv6 code size is approximately 11.5Kbyte and the RAM usage around 1.8Kbyte. For an additional NEIGHBOR count 35bytes, 25 for an additional PREFIX, 7 for an additional DEFROUTER, and 25 for an additional ADDRESS.

IPv6 Link Layer dependencies

The IPv6 stack can potentially run on very different link layers (ethernet, 802.15.4, 802.11, etc). The link-layer influences the following IP layer objects:

uip_lladdr_t, the link-layer address type, and its length, #UIP_LLADDR_LEN.
struct uip_eth_addr {

uint8_t addr[6];

};

typedef struct uip_eth_addr uip_lladdr_t;

#define UIP_LLADDR_LEN 6
uip_lladdr, the link-layer address of the node.
uip_lladdr_t uip_lladdr = {{0x00,0x06,0x98,0x00,0x02,0x32}};
UIP_ND6_OPT_LLAO_LEN, the length of the link-layer option in the different ND messages

Moreover, tcpip_output should point to the link-layer function used to send a packet. Similarly, the link-layer should call tcpip_input when an IP packet is received.

The code corresponding to the desired link layer is selected at compilation time (see for example the #UIP_LL_802154 flag).

IPv6 interaction with upper layers

The TCP and the UDP protocol are part of the uIP stack and were left unchanged by the IPv6 implementation. For the application layer, please refer to the application program interface.

IPv6 compliance

IPv6 Node Requirements, RFC4294

This section describes which parts of RFC4294 we are compliant with. For each section, we put between brackets the requirement level.
When all IPv6 related compile flags are set, our stack is fully compliant with RFC4294 (i.e. we implemement all the MUSTs), except for MLD support and redirect function support.

Note: RFC4294 is currently being updated by IETF 6man WG. One of the important points for us in the update is that after discussion on the 6man mailing list, IPSec support will become a SHOULD (was a MUST).

Sub IP layer
We support RFC2464 transmission of IPv6 packets over Ethernet
We will soon support RFC4944 transmission of IPv6 packets over 802.15.4

IP layer

IPv6 RFC2460 (MUST): When the compile flags UIP_CONF_IPV6_CHECKS and UIP_CONF_REASSEMBLY are set, full support
Neighbor Discovery RFC4861 (MUST): When the UIP_CONF_CHECKS and UIP_CONF_QUEUE_PKT flag are set, full support except redirect function
Address Autoconfiguration RFC4862 (MUST): When the UIP_CONF_CHECKS flag is set, full support except sending MLD report (see MLD)
Path MTU Discovery RFC 1981 (SHOULD): no support
Jumbograms RFC 2675 (MAY): no support
ICMPv6 RFC 4443 (MUST): full support
IPv6 addressing architecture RFC 3513 (MUST): full support
Privacy extensions for address autoconfiguration RFC 3041 (SHOULD): no support.
Default Address Selection RFC 3484 (MUST): full support.
MLDv1 (RFC 2710) and MLDv2 (RFC 3810) (conditional MUST applying here): no support. As we run IPv6 over Multicast or broadcast capable links (Ethernet or 802.15.4), the conditional MUST applies. We should be able to send an MLD report when joining a solicited node multicast group at address configuration time. This will be available in a later release.

DNS (RFC 1034, 1035, 3152, 3363, 3596) and DHCPv6 (RFC 3315) (conditional MUST)
no support

IPv4 Transition mechanisms RFC 4213 (conditional MUST)
no support

Mobile IP RFC 3775 (MAY / SHOULD)
no support

IPSec RFC 4301 4302 4303 2410 2404 2451 3602(MUSTs) 4305 (SHOULD)
no support

SNMP (MAY)
no support

IPv6 certification through ipv6ready alliance

IPv6ready is the certification authority for IPv6 implementations (http://www.ipv6ready.org). It delivers two certificates (phase 1 and phase 2).
When all the IPv6 related compile flags are set, we pass all the tests for phase 1.
We pass all the tests for phase 2 except:

the tests related to the redirect function
the tests related to PMTU discovery
test v6LC1.3.2C: A "bug" in the test suite (fragmentation states are not deleted after test v6LC1.3.2B) makes us fail this test unless we run it individually.
5.1.3: UDP port unreachable (the UDP message is too large for our implementation and the UDP code does not send any ICMP error message)

Macro Definition Documentation

#define UIP_ND6_RS_BUF ((uip_nd6_rs *)&uip_buf[uip_l2_l3_icmp_hdr_len])

Pointers to messages just after icmp header

Definition at line 107 of file uip-nd6.c.

Function Documentation

enum rpl_mode rpl_get_mode ( void )

Get the RPL mode.

Return values

The RPL mode

Definition at line 66 of file rpl.c.

enum rpl_mode rpl_set_mode ( enum rpl_mode mode )

Set the RPL mode.

Parameters

mode	The new RPL mode

Return values

The	previous RPL mode

Definition at line 72 of file rpl.c.

References NULL.

uint16_t uip_chksum	(	uint16_t *	buf,
		uint16_t	len
	)

Calculate the Internet checksum over a buffer.

The Internet checksum is the one's complement of the one's complement sum of all 16-bit words in the buffer.

See RFC1071.

Parameters

buf	A pointer to the buffer over which the checksum is to be computed.
len	The length of the buffer over which the checksum is to be computed.

Returns: The Internet checksum of the buffer.

Definition at line 335 of file uip6.c.

References uip_htons().

uip_ds6_nbr_t* uip_ds6_get_least_lifetime_neighbor ( void )

This searches inside the neighbor table for the neighbor that is about to expire the next.

Returns: A reference to the neighbor about to expire the next or NULL if table is empty.

Definition at line 280 of file uip-ds6-nbr.c.

References NULL, and stimer_remaining().

uip_ds6_nbr_t* uip_ds6_nbr_add	(	const uip_ipaddr_t *	ipaddr,
		const uip_lladdr_t *	lladdr,
		uint8_t	isrouter,
		uint8_t	state
	)

Adds a neighbor to the neighbor cache.

Parameters

ipaddr	IP address of the neighbor to add.
lladdr	Link-local address of the neighbor (may be unknown when added), NULL if not known (requires state to be set to NBR_INCOMPLETE)
isrouter	Set to 1 if neighbor is a router, to 0 if host or unknown
state	State of this entry. Possible values are: NBR_INCOMPLETE, NBR_REACHABLE, NBR_STALE, NBR_DELAY, NBR_PROBE

Definition at line 80 of file uip-ds6-nbr.c.

References NULL, stimer_set(), and uip_ipaddr_copy.

Referenced by tcpip_ipv6_output(), uip_nd6_ns_input(), and uip_nd6_ra_input().

uip_ipaddr_t* uip_ds6_nbr_ipaddr_from_lladdr ( const uip_lladdr_t * lladdr )

Returns IP address associated with link-local address, based on neighbor cache entry.

Definition at line 178 of file uip-ds6-nbr.c.

References NULL, and uip_ds6_nbr_ll_lookup().

uip_ds6_nbr_t* uip_ds6_nbr_ll_lookup ( const uip_lladdr_t * lladdr )

Lookup if a neighbor cache entry for given link-layer address exists.

Parameters

llpaddr link-layer address to look up

Returns: NULL if no entry was found, otherwise a pointer to that entry

Definition at line 171 of file uip-ds6-nbr.c.

Referenced by uip_ds6_link_neighbor_callback(), and uip_ds6_nbr_ipaddr_from_lladdr().

const uip_lladdr_t* uip_ds6_nbr_lladdr_from_ipaddr ( const uip_ipaddr_t * ipaddr )

Returns link-layer address associated with IP address, based on neighbor cache entry.

Definition at line 186 of file uip-ds6-nbr.c.

References NULL, uip_ds6_nbr_get_ll(), and uip_ds6_nbr_lookup().

Referenced by uip_ds6_route_add().

uip_ds6_nbr_t* uip_ds6_nbr_lookup ( const uip_ipaddr_t * ipaddr )

Lookup if a neighbor cache entry for given IP address exists.

Parameters

ipaddr IP address to look up

Returns: NULL if no entry was found, otherwise a pointer to that entry

Definition at line 156 of file uip-ds6-nbr.c.

References NULL.

Referenced by tcpip_ipv6_output(), uip_ds6_defrt_choose(), uip_ds6_nbr_lladdr_from_ipaddr(), uip_nd6_na_input(), uip_nd6_ns_input(), and uip_nd6_ra_input().

void uip_ds6_neighbors_init ( void )

Initialize neighbor cache.

Definition at line 74 of file uip-ds6-nbr.c.

References uip_ds6_nbr_rm().

Referenced by uip_ds6_init().

uint16_t uip_htons ( uint16_t val )

Convert a 16-bit quantity from host byte order to network byte order.

This function is primarily used for converting variables from host byte order to network byte order. For converting constants to network byte order, use the UIP_HTONS() macro instead.

Definition at line 2347 of file uip6.c.

References UIP_HTONS.

Referenced by mac_LowpanToEthernet(), roll_tm_icmp_input(), uip_chksum(), and uip_ipchksum().

void uip_icmp6_echo_reply_callback_add	(	struct uip_icmp6_echo_reply_notification *	n,
		uip_icmp6_echo_reply_callback_t	c
	)

Add a callback function for ping replies.

Parameters

n A struct uip_icmp6_echo_reply_notification that must have been allocated by the caller

c

A pointer to the callback function to be called

        This function adds a callback function to the list of
        callback functions that are called when an ICMP echo
        reply (ping reply) is received. This is used when
        implementing a ping protocol: attach a callback
        function to the ping reply, then send out a ping packet
        with uip_icmp6_send().

        The caller must have statically allocated a struct
        uip_icmp6_echo_reply_notification to hold the internal
        state of the callback function.

        When a ping reply packet is received, all registered
        callback functions are called. The callback functions
        must not modify the contents of the uIP buffer.

Definition at line 350 of file uip-icmp6.c.

References list_add(), and NULL.

void uip_icmp6_echo_reply_callback_rm ( struct uip_icmp6_echo_reply_notification * n )

Remove a callback function for ping replies.

Parameters

n	A struct uip_icmp6_echo_reply_notification that must have been previously added with uip_icmp6_echo_reply_callback_add() This function removes a callback function from the list of callback functions that are called when an ICMP echo reply (ping reply) is received.

Definition at line 360 of file uip-icmp6.c.

References list_remove().

void uip_icmp6_echo_reply_input ( void )

\ brief Process an echo reply

Perform a few checks, then call applications to inform that an echo reply has been received.

Definition at line 279 of file uip-icmp6.c.

References list_head(), list_item_next(), NULL, uip_ext_len, UIP_ICMP_BUF, UIP_IP_BUF, uip_ipaddr_copy, and uip_len.

Referenced by uip_process().

void uip_icmp6_echo_request_input ( void )

\ brief Process an echo request

Perform a few checks, then send an Echo reply. The reply is built here.

Definition at line 80 of file uip-icmp6.c.

References ICMP6_ECHO_REPLY, uip_ds6_select_src(), uip_ext_len, uip_icmp6chksum(), UIP_ICMP_BUF, UIP_IP_BUF, uip_ipaddr_copy, uip_is_addr_mcast, uip_len, and UIP_STAT.

Referenced by uip_process().

void uip_icmp6_error_output	(	uint8_t	type,
		uint8_t	code,
		uint32_t	param
	)

Send an icmpv6 error message.

Parameters

type	type of the error message
code	of the error message
type	32 bit parameter of the error message, semantic depends on error

Definition at line 167 of file uip-icmp6.c.

References ICMP6_PARAM_PROB, ICMP6_PARAMPROB_OPTION, uip_ds6_select_src(), uip_ext_len, UIP_ICMP6_ERROR_LEN, uip_icmp6chksum(), UIP_ICMP_BUF, UIP_IP_BUF, uip_ipaddr_copy, uip_is_addr_mcast, uip_is_addr_unspecified, uip_len, UIP_LINK_MTU, and UIP_STAT.

Referenced by uip_process().

void uip_icmp6_send	(	const uip_ipaddr_t *	dest,
		int	type,
		int	code,
		int	payload_len
	)

Send an icmpv6 message.

Parameters

dest	destination address of the message
type	type of the message
code	of the message
payload_len	length of the payload

Definition at line 254 of file uip-icmp6.c.

References tcpip_ipv6_output(), uip_ds6_select_src(), uip_icmp6chksum(), UIP_ICMP_BUF, UIP_IP_BUF, and uip_len.

uint16_t uip_icmp6chksum ( void )

Calculate the ICMP checksum of the packet in uip_buf.

Returns: The ICMP checksum of the ICMP packet in uip_buf

Definition at line 386 of file uip6.c.

Referenced by mac_translateIcmpLinkLayer(), uip_icmp6_echo_request_input(), uip_icmp6_error_output(), uip_icmp6_send(), uip_nd6_ns_input(), uip_nd6_ns_output(), uip_nd6_rs_output(), and uip_process().

void uip_init ( void )

uIP initialization function.

This function should be called at boot up to initilize the uIP TCP/IP stack.

Definition at line 410 of file uip6.c.

References uip_udp_conn::lport, UIP_CONNS, uip_ds6_init(), UIP_LISTENPORTS, and UIP_UDP_CONNS.

uint16_t uip_ipchksum ( void )

Calculate the IP header checksum of the packet header in uip_buf.

The IP header checksum is the Internet checksum of the 20 bytes of the IP header.

Returns: The IP header checksum of the IP header in the uip_buf buffer.

Definition at line 342 of file uip6.c.

References uip_htons(), and UIP_LLH_LEN.

void uip_process ( uint8_t flag )

process the options within a hop by hop or destination option header

Return values

0,:	nothing to send,
1,:	drop pkt
2,:	ICMP error message to send

Call echo reply input function.

Definition at line 918 of file uip6.c.

References ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_NOPORT, ICMP6_DST_UNREACH_NOTNEIGHBOR, ICMP6_ECHO_REPLY, ICMP6_ECHO_REQUEST, ICMP6_NA, ICMP6_NS, ICMP6_PACKET_TOO_BIG, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_HEADER, ICMP6_PARAMPROB_NEXTHEADER, ICMP6_RA, ICMP6_ROLL_TM, ICMP6_RPL, ICMP6_RS, ICMP6_TIME_EXCEED_TRANSIT, ICMP6_TIME_EXCEEDED, uip_conn::initialmss, uip_conn::len, uip_conn::lport, uip_udp_conn::lport, uip_conn::mss, uip_conn::nrtx, NULL, uip_conn::rcv_nxt, uip_conn::ripaddr, uip_udp_conn::ripaddr, roll_tm_icmp_input(), uip_conn::rport, uip_udp_conn::rport, uip_conn::rto, uip_conn::sa, uip_conn::snd_nxt, uip_conn::sv, uip_conn::tcpstateflags, uip_conn::timer, uip_udp_conn::ttl, uip_add32(), UIP_APPCALL, uip_appdata, uip_conn, UIP_CONNS, uip_ds6_is_my_addr, uip_ds6_is_my_maddr, uip_ds6_select_src(), uip_ext_bitmap, UIP_EXT_HDR_BITMAP_HBHO, uip_ext_len, UIP_HTONS, uip_icmp6_echo_reply_input(), uip_icmp6_echo_request_input(), uip_icmp6_error_output(), uip_icmp6chksum(), UIP_ICMP_BUF, UIP_IP_BUF, uip_ipaddr_copy, uip_is_addr_link_local, uip_is_addr_loopback, uip_is_addr_mcast, uip_is_addr_mcast_routable, uip_is_addr_unspecified, uip_len, UIP_LINK_MTU, UIP_LISTENPORTS, UIP_LLH_LEN, UIP_MAXRTX, UIP_MAXSYNRTX, uip_nd6_na_input(), uip_nd6_ns_input(), uip_nd6_ra_input(), uip_next_hdr, UIP_PROTO_HBHO, UIP_RECEIVE_WINDOW, UIP_RTO, UIP_STAT, UIP_TCP_MSS, uip_tcpchksum(), UIP_TIME_WAIT_TIMEOUT, uip_udp_conn, UIP_UDP_CONNS, and uip_udpchksum().

void uip_send	(	const void *	data,
		int	len
	)

Send data on the current connection.

This function is used to send out a single segment of TCP data. Only applications that have been invoked by uIP for event processing can send data.

The amount of data that actually is sent out after a call to this function is determined by the maximum amount of data TCP allows. uIP will automatically crop the data so that only the appropriate amount of data is sent. The function uip_mss() can be used to query uIP for the amount of data that actually will be sent.

Note: This function does not guarantee that the sent data will arrive at the destination. If the data is lost in the network, the application will be invoked with the uip_rexmit() event being set. The application will then have to resend the data using this function.

Parameters

data	A pointer to the data which is to be sent.
len	The maximum amount of data bytes to be sent.

Definition at line 2359 of file uip6.c.

References NULL, UIP_BUFSIZE, and UIP_LLH_LEN.

Variable Documentation

void* uip_appdata

Pointer to the application data in the packet buffer.

This pointer points to the application data when the application is called. If the application wishes to send data, the application may use this space to write the data into before calling uip_send().

Definition at line 173 of file uip6.c.

Referenced by slipdev_send(), uip_arp_out(), uip_fw_forward(), uip_process(), uip_split_output(), and uip_tcpchksum().

struct uip_conn* uip_conn

Pointer to the current TCP connection.

The uip_conn pointer can be used to access the current TCP connection.

Definition at line 196 of file uip6.c.

uint8_t uip_ext_len = 0

length of the extension headers read.

The length of the extension headers.

updated each time we process a header

Definition at line 136 of file uip6.c.

Referenced by roll_tm_icmp_input(), tcpip_input(), tcpip_ipv6_output(), uip_icmp6_echo_reply_input(), uip_icmp6_echo_request_input(), uip_icmp6_error_output(), uip_nd6_ns_input(), uip_nd6_ns_output(), and uip_process().

uint16_t uip_len

The length of the packet in the uip_buf buffer.

The global variable uip_len holds the length of the packet in the uip_buf buffer.

When the network device driver calls the uIP input function, uip_len should be set to the length of the packet in the uip_buf buffer.

When sending packets, the device driver should use the contents of the uip_len variable to determine the length of the outgoing packet.

Definition at line 184 of file uip6.c.

Referenced by mac_ethernetToLowpan(), mac_LowpanToEthernet(), mac_translateIcmpLinkLayer(), roll_tm_icmp_input(), slipdev_send(), tcpip_input(), tcpip_ipv6_output(), uip_arp_arpin(), uip_arp_out(), uip_ds6_neighbor_periodic(), uip_ds6_periodic(), uip_fw_forward(), uip_fw_output(), uip_icmp6_echo_reply_input(), uip_icmp6_echo_request_input(), uip_icmp6_error_output(), uip_icmp6_send(), uip_nd6_na_input(), uip_nd6_ns_input(), uip_nd6_ns_output(), uip_nd6_ra_input(), uip_nd6_rs_output(), uip_process(), and uip_split_output().

uint8_t* uip_next_hdr

Type of the next header in IPv6 header or extension headers.

Can be the next header field in the IPv6 header or in an extension header. When doing fragment reassembly, we must change the value of the next header field in the header before the fragmentation header, hence we need a pointer to this field.

Definition at line 129 of file uip6.c.

Referenced by uip_process().

Modules

Files

Data Structures

Macros

Typedefs

Functions

Variables

"DS6" Data structures

ICMPv6 message types

ICMPv6 Destination Unreachable message codes

ICMPv6 Time Exceeded message codes

ICMPv6 Parameter Problem message codes

ICMPv6 RFC4443 Message processing and sending

Pointers to the header structures.

Layer 2 variables

Layer 3 variables

Buffer defines

Buffer variables

General variables

TCP defines

Detailed Description

Introduction

IPv6 Protocol Implementation

IPv6 (RFC 2460)

Interface and Addressing (RFC 4291, RFC 4861 p.51, RFC 4862 p.10)

Multicast support

Neighbor Discovery (RFC 4861)

Stateless Address Autoconfiguration (RFC 4862)

ICMPv6 (RFC 4443)

IPv6 Timers and Processes

Compile time flags and variables

IPv6 Buffers

IPv6 Code Size

IPv6 Link Layer dependencies

IPv6 interaction with upper layers

IPv6 compliance

IPv6 Node Requirements, RFC4294

IPv6 certification through ipv6ready alliance

Macro Definition Documentation

Function Documentation

Variable Documentation