Packets processing¶

Matchers¶

Matchers are criteria used to match a network packet against a specific rule. For example, a matcher could be used to match the destination IP field of an IPv4 packet to a specific IP address.

Matchers are composed of:

A type, defining which data in the network packet to match the payload against. In the example about, the type would be related to IPv4 destination address field.
An operator, to know how to compare the data in the packet defined by the type to the payload contained in the matcher. For example, we want the matcher to match when the IPv4 destination address is equal to the IP address in the payload.
A payload, which is compared to the similar value in the network packet.

Defines

_cleanup_bf_matcher_¶: Automatically destroy bf_matcher objects going out of the scope.

Enums

enum bf_matcher_type¶

Matcher type.

The matcher type define which header/field of a packet is to be used to match against the payload.

Values:

enumerator BF_MATCHER_META_L3_PROTO¶: Matches the L3 protocol.

enumerator BF_MATCHER_META_L4_PROTO¶: Matches the L4 protocol, idependently from the L3 protocol.

enumerator BF_MATCHER_IP4_SRC_ADDR¶: Matches IPv4 source address.

enumerator BF_MATCHER_IP4_DST_ADDR¶: Matches IPv4 destination address.

enumerator BF_MATCHER_IP4_PROTO¶: Matches against the IPv4 protocol field.

enumerator BF_MATCHER_IP6_SADDR¶: Matches IPv6 source address.

enumerator BF_MATCHER_IP6_DADDR¶: Matches IPv6 destination address.

enumerator BF_MATCHER_TCP_SPORT¶: Matches against the TCP source port.

enumerator BF_MATCHER_TCP_DPORT¶: Matches against the TCP destination port.

enumerator BF_MATCHER_TCP_FLAGS¶: Matchers against the TCP flags.

enumerator BF_MATCHER_UDP_SPORT¶: Matches against the UDP source port.

enumerator BF_MATCHER_UDP_DPORT¶: Matches against the UDP destination port.

enumerator _BF_MATCHER_TYPE_MAX¶

enum bf_matcher_tcp_flag¶

Define the TCP flags values as number of shifts of 1.

Values:

enumerator BF_MATCHER_TCP_FLAG_FIN = 0¶

enumerator BF_MATCHER_TCP_FLAG_SYN = 1¶

enumerator BF_MATCHER_TCP_FLAG_RST = 2¶

enumerator BF_MATCHER_TCP_FLAG_PSH = 3¶

enumerator BF_MATCHER_TCP_FLAG_ACK = 4¶

enumerator BF_MATCHER_TCP_FLAG_URG = 5¶

enumerator BF_MATCHER_TCP_FLAG_ECE = 6¶

enumerator BF_MATCHER_TCP_FLAG_CWR = 7¶

enumerator _BF_MATCHER_TCP_FLAG_MAX¶

enum bf_matcher_op¶

Matcher comparison operator.

The matcher comparison operator defines the type of comparison to operator for a specific matcher.

Values:

enumerator BF_MATCHER_EQ¶: Test for equality.

enumerator BF_MATCHER_NE¶: Test for inequality.

enumerator BF_MATCHER_ANY¶: Test for partial subset match.

enumerator BF_MATCHER_ALL¶: Test for complete subset match.

enumerator BF_MATCHER_IN¶: Test if the value is in a set.

enumerator _BF_MATCHER_OP_MAX¶

Functions

int bf_matcher_new(struct bf_matcher **matcher, enum bf_matcher_type type, enum bf_matcher_op op, const void *payload, size_t payload_len)¶

Allocate and initalise a new matcher.

Parameters:

matcher – Matcher object to allocate and initialise. Can’t be NULL. On success, contain a pointer to the matcher object, unchanged on error.
type – Matcher type.
op – Comparison operator.
payload – Payload of the matcher, its content and size depends on type . Can be NULL but only if payload_len is 0, in which case there is no payload.
payload_len – Length of the payload.

Returns:

0 on success, or negative errno value on failure.

int bf_matcher_new_from_marsh(struct bf_matcher **matcher, const struct bf_marsh *marsh)¶

Allocate a new matcher and initialise it from serialised data.

Parameters:

matcher – On success, points to the newly allocated and initialised matcher. Can’t be NULL.
marsh – Serialised data to use to initialise the matcher.

Returns:

0 on success, or negative errno value on failure.

void bf_matcher_free(struct bf_matcher **matcher)¶

Deinitialise and deallocate a matcher.

Parameters:

matcher – Matcher. Can’t be NULL.

int bf_matcher_marsh(const struct bf_matcher *matcher, struct bf_marsh **marsh)¶

Serialise a matcher.

Parameters:

matcher – Matcher object to serialise. Can’t be NULL.
marsh – On success, contains the serialised matcher. Can’t be NULL.

void bf_matcher_dump(const struct bf_matcher *matcher, prefix_t *prefix)¶

Dump a matcher.

Parameters:

matcher – Matcher to dump.
prefix – Prefix for each printed line.

const char *bf_matcher_type_to_str(enum bf_matcher_type type)¶

Convert a matcher type to a string.

Parameters:

type – The matcher type to convert. Must be a valid bf_matcher_type .

Returns:

String representation of the matcher type.

int bf_matcher_type_from_str(const char *str, enum bf_matcher_type *type)¶

Convert a string to the corresponding matcher type.

Parameters:

str – String containing the name of a matcher type.
type – Matcher type value, if the parsing succeeds.

Returns:

0 on success, or negative errno value on failure.

const char *bf_matcher_op_to_str(enum bf_matcher_op op)¶

Convert a matcher operator to a string.

Parameters:

op – The matcher operator to convert. Must be a valid bf_matcher_op

Returns:

String representation of the matcher operator.

int bf_matcher_op_from_str(const char *str, enum bf_matcher_op *op)¶

Convert a string to the corresponding matcher operator.

Parameters:

str – String containing the name of a matcher operator.
op – Matcher operator value, if the parsing succeeds.

Returns:

0 on success, or negative errno value on failure.

const char *bf_matcher_tcp_flag_to_str(enum bf_matcher_tcp_flag flag)¶

Convert a TCP flag to a string.

Parameters:

flag – TCP flag to convert.

Returns:

String representation of the TCP flag.

int bf_matcher_tcp_flag_from_str(const char *str, enum bf_matcher_tcp_flag *flag)¶

Convert a string to the corresponding TCP flag.

Parameters:

str – String containing the name of the TCP flag.
flag – TCP flag value, if the parsing succeeds.

Returns:

0 on success, or negative errno value on failure.

struct bf_matcher_ip4_addr¶

#include <core/matcher.h>

Defines the structure of the payload for bf_matcher’s BF_MATCHER_IP4_SRC_ADDR and BF_MATCHER_IP4_DST_ADDR types.

Public Members

uint32_t addr¶

uint32_t mask¶

struct bf_matcher_ip6_addr¶

#include <core/matcher.h>

Defines the payload for the IPv6 address matcher.

Public Members

uint64_t addr[2]¶: 128-bits IPv6 address.

uint64_t mask[2]¶: 128-bits IPv6 mask.

struct bf_matcher¶

#include <core/matcher.h>

Matcher definition.

Matchers are criterias to match the packet against. A set of matcher defines what a rule should match on.

Public Members

enum bf_matcher_type type¶: Matcher type.

enum bf_matcher_op op¶: Comparison operator.

size_t len¶: Total matcher size (including payload).

uint8_t payload[0]¶: Payload to match the packet against (if any).