Ematch used to classify CAN frames according to their identifiers
This ematch enables effective filtering of CAN frames (AF_CAN) based
on CAN identifiers with masking of compared bits. Implementation
utilizes bitmap based classification for standard frame format (SFF)
which is optimized for minimal overhead.
Signed-off-by: Rostislav Lisovy <lisovy@gmail.com>
diff --git a/tc/Makefile b/tc/Makefile
index dfbfac5..ccf6acd 100644
--- a/tc/Makefile
+++ b/tc/Makefile
@@ -45,6 +45,7 @@
TCMODULES += em_nbyte.o
TCMODULES += em_cmp.o
TCMODULES += em_u32.o
+TCMODULES += em_canid.o
TCMODULES += em_meta.o
TCMODULES += q_mqprio.o
TCMODULES += q_codel.o
diff --git a/tc/em_canid.c b/tc/em_canid.c
new file mode 100644
index 0000000..16f6ed5
--- /dev/null
+++ b/tc/em_canid.c
@@ -0,0 +1,191 @@
+/*
+ * em_canid.c Ematch rule to match CAN frames according to their CAN identifiers
+ *
+ * This program is free software; you can distribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ *
+ * Idea: Oliver Hartkopp <oliver.hartkopp@volkswagen.de>
+ * Copyright: (c) 2011 Czech Technical University in Prague
+ * (c) 2011 Volkswagen Group Research
+ * Authors: Michal Sojka <sojkam1@fel.cvut.cz>
+ * Pavel Pisa <pisa@cmp.felk.cvut.cz>
+ * Rostislav Lisovy <lisovy@gmail.cz>
+ * Funded by: Volkswagen Group Research
+ *
+ * Documentation: http://rtime.felk.cvut.cz/can/socketcan-qdisc-final.pdf
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <syslog.h>
+#include <fcntl.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <string.h>
+#include <errno.h>
+#include <linux/can.h>
+#include <inttypes.h>
+#include "m_ematch.h"
+
+#define EM_CANID_RULES_MAX 400 /* Main reason for this number is Nelink
+ message size limit equal to Single memory page size. When dump()
+ is invoked, there are even some ematch related headers sent from
+ kernel to userspace together with em_canid configuration --
+ 400*sizeof(struct can_filter) should fit without any problems */
+
+extern struct ematch_util canid_ematch_util;
+struct rules {
+ struct can_filter *rules_raw;
+ int rules_capacity; /* Size of array allocated for rules_raw */
+ int rules_cnt; /* Actual number of rules stored in rules_raw */
+};
+
+static void canid_print_usage(FILE *fd)
+{
+ fprintf(fd,
+ "Usage: canid(IDLIST)\n" \
+ "where: IDLIST := IDSPEC [ IDLIST ]\n" \
+ " IDSPEC := { ’sff’ CANID | ’eff’ CANID }\n" \
+ " CANID := ID[:MASK]\n" \
+ " ID, MASK := hexadecimal number (i.e. 0x123)\n" \
+ "Example: canid(sff 0x123 sff 0x124 sff 0x125:0xf)\n");
+}
+
+static int canid_parse_rule(struct rules *rules, struct bstr *a, int iseff)
+{
+ unsigned int can_id = 0;
+ unsigned int can_mask = 0;
+
+ if (sscanf(a->data, "%"SCNx32 ":" "%"SCNx32, &can_id, &can_mask) != 2) {
+ if (sscanf(a->data, "%"SCNx32, &can_id) != 1) {
+ return -1;
+ } else {
+ can_mask = (iseff) ? CAN_EFF_MASK : CAN_SFF_MASK;
+ }
+ }
+
+ /* Stretch rules array up to EM_CANID_RULES_MAX if necessary */
+ if (rules->rules_cnt == rules->rules_capacity) {
+ if (rules->rules_capacity <= EM_CANID_RULES_MAX/2) {
+ rules->rules_capacity *= 2;
+ rules->rules_raw = realloc(rules->rules_raw,
+ sizeof(struct can_filter) * rules->rules_capacity);
+ } else {
+ return -2;
+ }
+ }
+
+ rules->rules_raw[rules->rules_cnt].can_id =
+ can_id | ((iseff) ? CAN_EFF_FLAG : 0);
+ rules->rules_raw[rules->rules_cnt].can_mask =
+ can_mask | CAN_EFF_FLAG;
+
+ rules->rules_cnt++;
+
+ return 0;
+}
+
+static int canid_parse_eopt(struct nlmsghdr *n, struct tcf_ematch_hdr *hdr,
+ struct bstr *args)
+{
+ int iseff = 0;
+ int ret = 0;
+ struct rules rules = {
+ .rules_capacity = 25, /* Denominator of EM_CANID_RULES_MAX
+ Will be multiplied by 2 to calculate the size for realloc() */
+ .rules_cnt = 0
+ };
+
+#define PARSE_ERR(CARG, FMT, ARGS...) \
+ em_parse_error(EINVAL, args, CARG, &canid_ematch_util, FMT, ##ARGS)
+
+ if (args == NULL)
+ return PARSE_ERR(args, "canid: missing arguments");
+
+ rules.rules_raw = malloc(sizeof(struct can_filter) * rules.rules_capacity);
+ memset(rules.rules_raw, 0, sizeof(struct can_filter) * rules.rules_capacity);
+
+ do {
+ if (!bstrcmp(args, "sff")) {
+ iseff = 0;
+ } else if (!bstrcmp(args, "eff")) {
+ iseff = 1;
+ } else {
+ ret = PARSE_ERR(args, "canid: invalid key");
+ goto exit;
+ }
+
+ args = bstr_next(args);
+ if (args == NULL) {
+ ret = PARSE_ERR(args, "canid: missing argument");
+ goto exit;
+ }
+
+ ret = canid_parse_rule(&rules, args, iseff);
+ if (ret == -1) {
+ ret = PARSE_ERR(args, "canid: Improperly formed CAN ID & mask\n");
+ goto exit;
+ } else if (ret == -2) {
+ ret = PARSE_ERR(args, "canid: Too many arguments on input\n");
+ goto exit;
+ }
+ } while ((args = bstr_next(args)) != NULL);
+
+ addraw_l(n, MAX_MSG, hdr, sizeof(*hdr));
+ addraw_l(n, MAX_MSG, rules.rules_raw,
+ sizeof(struct can_filter) * rules.rules_cnt);
+
+#undef PARSE_ERR
+exit:
+ free(rules.rules_raw);
+ return ret;
+}
+
+static int canid_print_eopt(FILE *fd, struct tcf_ematch_hdr *hdr, void *data,
+ int data_len)
+{
+ struct can_filter *conf = data; /* Array with rules */
+ int rules_count;
+ int i;
+
+ rules_count = data_len / sizeof(struct can_filter);
+
+ for (i = 0; i < rules_count; i++) {
+ struct can_filter *pcfltr = &conf[i];
+
+ if (pcfltr->can_id & CAN_EFF_FLAG) {
+ if (pcfltr->can_mask == (CAN_EFF_FLAG | CAN_EFF_MASK))
+ fprintf(fd, "eff 0x%"PRIX32,
+ pcfltr->can_id & CAN_EFF_MASK);
+ else
+ fprintf(fd, "eff 0x%"PRIX32":0x%"PRIX32,
+ pcfltr->can_id & CAN_EFF_MASK,
+ pcfltr->can_mask & CAN_EFF_MASK);
+ } else {
+ if (pcfltr->can_mask == (CAN_EFF_FLAG | CAN_SFF_MASK))
+ fprintf(fd, "sff 0x%"PRIX32,
+ pcfltr->can_id & CAN_SFF_MASK);
+ else
+ fprintf(fd, "sff 0x%"PRIX32":0x%"PRIX32,
+ pcfltr->can_id & CAN_SFF_MASK,
+ pcfltr->can_mask & CAN_SFF_MASK);
+ }
+
+ if ((i + 1) < rules_count)
+ fprintf(fd, " ");
+ }
+
+ return 0;
+}
+
+struct ematch_util canid_ematch_util = {
+ .kind = "canid",
+ .kind_num = TCF_EM_CANID,
+ .parse_eopt = canid_parse_eopt,
+ .print_eopt = canid_print_eopt,
+ .print_usage = canid_print_usage
+};
