Enumerations | |
| enum | P_FILTER { FILTER_TYPE_LOCATION = 0x001, FILTER_TYPE_ID = 0x002, FILTER_TYPE_ACL = 0x004, FILTER_TYPE_ACL_POSITION = 0x008, FILTER_TYPE_FILTER = 0x010, FILTER_TYPE_MASK = 0x0ff, FILTER_CONCAT_AND = 0x0100, FILTER_CONCAT_OR = 0x0200, FILTER_CONCAT_MASK = 0x0300, FILTER_MODE_WILDCARD = 0x400, FILTER_MODE_NOT = 0x800000 } |
Functions | |
| int | p_filter_create (const char *filter_name) |
| Create a new filter. | |
| int | p_filter_destroy (int filter) |
| Destroy a filter. | |
| int | p_filter_add (int filter, int type, const void *arg) |
| Adds a new condition to a filter. | |
| int | p_filter_add_str (int filter, const char *char_type, const char *char_arg) |
| Adds a new condition to a filter, takes strings as arguments. | |
| int | p_filter_apply (int filter, struct p_packet *packet) |
| Applies a filter onto a packet. | |
| void | p_describe_filter (int filter) |
| Prints out all information about a filter. | |
| void * | p_filter_arg (int filter) |
| Get a pointer for a filter. | |
| enum P_FILTER |
Filter type
Definition at line 50 of file filter_enum.h.
| void p_describe_filter | ( | int | filter | ) |
Prints out all information about a filter.
Debug function, which prints out all internal information of filter to stdout.
| filter | Filter that should be described |
| int p_filter_add | ( | int | filter, | |
| int | type, | |||
| const void * | arg | |||
| ) |
Adds a new condition to a filter.
We have three types of conditions, which can be filtered: The sender-ID of a packet (FILTER_TYPE_ID), the location, where the sending particle is located (FILTER_TYPE_LOCATION) and the type of the ACL-tuples, which are inside a packet (FILTER_TYPE_ACL).
The use of FILTER_TYPE_ID and FILTER_TYPE_LOCATION is very similar, so I will only show some examples for FILTER_TYPE_ID. The simplest way to add a filter for an ID is to initialize an 8 byte long field with the ID and then adding this ID to the filter.
uint8_t id[8] = { 1, 1, 1, 1, 129, 150, 24, 27 }; p_filter_add(filter_nr, FILTER_TYPE_ID|FILTER_CONCAT_AND, id);
As you also can negate a filter, the following filter will return exactly the packets, the last one has not returned:
uint8_t id[8] = { 1, 1, 1, 1, 129, 150, 24, 27 }; p_filter_add(filter_nr, FILTER_TYPE_ID|FILTER_CONCAT_AND|FLTER_MODE_NOT, id);
Another feature is filtering with wildcards. There are two possible wildcard-operators: ? and *. If you just want to use a wildcard for one (or more) single bytes of the ID, you should use ?. A filter_add-operation for such a wildcard would look like this:
p_filter_add(filter_nr, FILTER_TYPE_ID|FILTER_CONCAT_AND|FLTER_MODE_WILDCARD, "1.1.1.1.129.150.24.?");
If you are interested in packet-IDs with a special prefix, you can also use *. The following filter will return exactly the same packets as the last one:
p_filter_add(filter_nr, FILTER_TYPE_ID|FILTER_CONCAT_AND|FLTER_MODE_WILDCARD, "1.1.1.1.129.150.24.*");
As already said, filtering for locations goes exactly the same way as for IDs, you just have to take FILTER_TYPE_LOCATION instead of FILTER_TYPE_ID and you have to change the length of the conditions from 8 byte to 44 byte.
The third possibility is to filter by the ACL-types a packet contains. The following code would add a filter for the ACL-type ACM:
uint8_t acl[8] = { 165, 14};
p_filter_add(filter_nr, FILTER_TYPE_ACL|FILTER_CONCAT_AND, acl);
If you want to put in a 3-byte ACL-string, you can use p_util_str2acl:
p_filter_add(filter_nr, FILTER_TYPE_ACL|FILTER_CONCAT_AND, p_util_str2acl("ACM", NULL));
It's not possible to filter ACL-types with wildcards. Of cause, FILTER_TYPE_NOT is possible for FILTER_TYPE_ACL.
Of cause, you can add more than one condition to a filter, you must just use p_filter_add for several times.
Each filter condition can be contacted with a logical AND (FILTER_CONCAT_AND) or a logical OR (FILTER_CONCAT_OR) to the existing filter. The AND-operator is binding stronger than OR.
PLEASE NOTE: The first condition which is added to a filter must be conceded by AND. As every filter is initialized with "TRUE", concating the first condition with OR would result in "TRUE OR condition" which is always TRUE. Cause of this, p_filter_add will return -1, if the first condition is added with OR!
p_filter_add can also combine 2 existing filters by using FILTER_TYPE_FILTER. In this case, the 3rd argument of p_filter_add must be p_filter_arg(filter_xy) with filter_xy as the filter, which will be added to the filter in the first argument of p_filter_add.
p_filter_add(filter_nr, FILTER_TYPE_FILTER|FILTER_CONCAT_AND, p_filter_arg(filter_nr2));
| filter | pointer to the filter, to which the new condition should be added | |
| type | a combination of the FILTER_ Constants. | |
| arg | the argument for the given FILTER_ type. |
| int p_filter_add_str | ( | int | filter, | |
| const char * | char_type, | |||
| const char * | char_arg | |||
| ) |
Adds a new condition to a filter, takes strings as arguments.
p_filter_add_str adds a new condition to a filter and takes strings as arguments.
The type argument indicates how the arg argument should be interpreted and added to the filter chain.
It must conform to the following Format:
TYPE.CONCAT.[NOT].[WILDCARD] where TYPE is one of ID, LOC or ACL and CONCAT is AND or OR
NOT and WILDCARD are optional.
I is neccessary to hold this arguments in the given sequence. For example, OR.ACL.NOT is not allowed, it must be ACL.OR.NOT
The "arg" string holds the data you want to add to the filter.
Examples:
int filter = p_filter_create("filter"); p_filter_add_str( filter, "ID.AND.NOT", "1.2.3.4.5.6.7.8" );
For detailed instructions on filter conditions, see documentation of p_filter_add
| filter | pointer to the filter, to which the new condition should be added | |
| char_type | the type of filter. | |
| char_arg | the argument for the filter condition. |
| int p_filter_apply | ( | int | filter, | |
| struct p_packet * | packet | |||
| ) |
Applies a filter onto a packet.
| filter | Filter that should be applied | |
| packet | CL-packet that should be tested |
| void* p_filter_arg | ( | int | filter | ) |
Get a pointer for a filter.
Little util that is only needed when adding one filter into another.
| filter | Filter, for which the pointer should be get |
| int p_filter_create | ( | const char * | filter_name | ) |
Create a new filter.
Creates a new Filter. The filter will be initialized with "AND 1", so it will return true for every packet until no other conditions have been added.
| filter_name | Name of the new filter, only used by the p_filter_describe() function. |
| int p_filter_destroy | ( | int | filter | ) |
Destroy a filter.
Destroys a filter and frees memory allocated for internal structures.
| filter | Pointer to the filter |
1.5.1