UNISAP(3)

NAME
unimsg, unisve_check_addr, unisve_check_selector, unisve_check_blli_id2, unisve_check_blli_id3, unisve_check_bhli, unisve_check_sap, unisve_overlap_addr, unisve_overlap_selector, unisve_overlap_blli_id2, unisve_overlap_blli_id3, unisve_overlap_bhli, unisve_overlap_sap, unisve_is_catchall, unisve_match - ATM signalling library - ATM SAP handling

LIBRARY
Begemot ATM signalling library (libunimsg, -lunimsg)

SYNOPSIS
#include <uni4/unisap.h>
int
unisve_check_addr(const struct unisve_addr *sve);
int
unisve_check_selector(const struct unisve_selector *sve);
int
unisve_check_blli_id2(const struct unisve_blli_id2 *sve);
int
unisve_check_blli_id3(const struct unisve_blli_id3 *sve);
int
unisve_check_bhli(const struct unisve_bhli *sve);
int
unisve_check_sap(const struct uni_sap *sve);
int
unisve_overlap_addr(const struct unisve_addr *sve1, const struct unisve_addr *sve2);
int
unisve_overlap_selector(const struct unisve_selector *sve1, const struct unisve_selector *sve2);
int
unisve_overlap_blli_id2(const struct unisve_blli_id2 *sve1, const struct unisve_blli_id2 *sve2);
int
unisve_overlap_blli_id3(const struct unisve_blli_id3 *sve1, const struct unisve_blli_id3 *sve2);
int
unisve_overlap_bhli(const struct unisve_bhli *sve1, const struct unisve_bhli *sve2);
int
unisve_overlap_sap(const struct uni_sap *sap1, const struct uni_sap *sap2);
int
unisve_is_catchall(const struct uni_sap *sap);
int
unisve_match(const struct uni_sap *sap, const struct uni_ie_called *called, const struct uni_ie_blli *blli, const struct uni_ie_bhli *bhli);

DESCRIPTION
The unimsg library contains functions to handle Service Access Points (SAP) and SAP Vector Elements (SVE) as specified in the ATM Forum ATM API Semantic Description. SAPs are the analog of TCP and UDP ports in the ATM world. As usually in ATM they are a couple of orders of magnitude more complex as their Internet equivalent. See the ATM Forum document for a description.

A SAP is a data structure:

    struct uni_sap {
    	struct unisve_addr	addr;
    	struct unisve_selector	selector;
    	struct unisve_blli_id2	blli_id2;
    	struct unisve_blli_id3	blli_id3;
    	struct unisve_bhli	bhli;
    };

that consists of 5 elements matching different information elements in the SETUP message. Each of these elements has a tag that defines how the SVE is to be matched with the information element. The tag is one of

UNISVE_ABSENT
    The information element has to absent from the SETUP message.

UNISVE_PRESENT
    The information element has to be present in the SETUP message and must match the SVE.

UNISVE_ANY
    The information element may be absent from the SETUP message or may have any value.

The called address is matched by a

    struct unisve_addr {
    	enum unisve_tag	tag;
    	enum uni_addr_type type;/* type of address */
    	enum uni_addr_plan plan;/* addressing plan */
    	uint32_t	len;	/* length of address */
    	u_char		addr[UNI_ADDR_MAXLEN];
    };

Here type is the type of address and plan is the address plan. len is the length of the address (for ATME addresses not counting the selector byte) and addr is the address itself.

In case of ATME addresses the selector byte is matched by a

    struct unisve_selector {
    	enum unisve_tag	tag;
    	uint8_t		selector;
    };

Here selector is the selector byte that must match the 20th byte of the ATME calling address from the SETUP message.

The BLLI information element is matched by two SVEs: one for layer 2 options and one for layer 3 options. The layer 2 SVE is:

    struct unisve_blli_id2 {
    	enum unisve_tag	tag;
    	uint8_t		proto:5;/* the protocol */
    	uint8_t		user:7;	/* user specific protocol */
    };

Where the user fields is matched only if the proto field specifies UNI_BLLI_L2_USER. The layer 3 SVE is:

    struct unisve_blli_id3 {
    	enum unisve_tag	tag;
    	uint8_t		proto:5;/* L3 protocol */
    	uint8_t		user:7;	/* user specific protocol */
    	uint8_t		ipi:8;	/* ISO/IEC TR 9557 IPI */
    	uint32_t	oui:24;	/* IEEE 802.1 OUI */
    	uint32_t	pid:16;	/* IEEE 802.1 PID */
    	uint32_t	noipi;	/* ISO/IEC TR 9557 per frame */
    };

For the exact rules how matching occures refer to the source code or the ATM Forum document.

Finally the BHLI information element is matched with a

    struct unisve_bhli {
    	enum unisve_tag	tag;
    	enum uni_bhli	type;	/* type of info */
    	uint32_t	len;	/* length of info */
    	uint8_t		info[8];/* info itself */
    };

For each SVE type there is a function that checks whether the SVE is correct specified. The functions unisve_check_addr(), unisve_check_selector(), unisve_check_blli_id2(), unisve_check_blli_id3(), and unisve_check_bhli() return one of the following error codes:

    enum {
    	UNISVE_OK = 0,
    	UNISVE_ERROR_BAD_TAG,
    	UNISVE_ERROR_TYPE_PLAN_CONFLICT,
    	UNISVE_ERROR_ADDR_SEL_CONFLICT,
    	UNISVE_ERROR_ADDR_LEN,
    	UNISVE_ERROR_BAD_ADDR_TYPE,
    	UNISVE_ERROR_BAD_BHLI_TYPE,
    	UNISVE_ERROR_BAD_BHLI_LEN,
    };

A code of UNISVE_OK means that the SVE has no error. The function unisve_check_sap() checks a complete SAP and returns one of the above codes.

There is a definition UNISVE_ERRSTR that evaluates to a comma separated list of strings that can be used to initializes an array of char pointers to map the error codes into human readable strings.

The ATM Forum document defines the concept of overlaping SAPs. This basically means, that an incoming SETUP could match more than one SAP (and more than one application) to receive the SETUP. For each SVE type there is a function that checks whether two SVEs overlap and there is a function that checks whether two SAPs overlap. The functions unisve_overlap_addr(), unisve_overlap_selector(), unisve_overlap_blli_id2(), unisve_overlap_blli_id3(), unisve_overlap_bhli(,, and) unisve_overlap_sap() return 1 if the SVEs or SAPs overlap and 0 if they do not. They assume, that the SAPs are correct.

The ATM Forum document specifies a catch-all SAP. The function unisve_is_catchall() returns 1 if the SAP is the catch-all SAP and 0 otherwise.

Finally the function unisve_match() is used to match a SAP against the information elements from a SETUP message. It returns 1 if they match and 0 otherwise.

SEE ALSO
libunimsg(3)

AUTHORS
Hartmut Brandt <harti@FreeBSD.org>