[dpdk-dev] [PATCH] ip_frag: add function rte_ip_frag_sweep_table()

["Fu, Qiaobin" <qiaobinf@bu.edu>]

Function rte_ip_frag_sweep_table() enables callers to
incrementally sweep IP frament tables for incomplete, expired fragments.

rte_ip_frag_sweep_table() is needed to identify
never-to-be-completed fragments during DDoS attacks.

Signed-off-by: Qiaobin Fu <qiaobinf@bu.edu>
Reviewed-by: Cody Doucette <doucette@bu.edu>
Reviewed-by: Michel Machado <michel@digirati.com.br>
---
 lib/librte_ip_frag/ip_frag_common.h     | 18 +++++++++++++++++
 lib/librte_ip_frag/ip_frag_internal.c   | 18 -----------------
 lib/librte_ip_frag/rte_ip_frag.h        | 17 ++++++++++++++++
 lib/librte_ip_frag/rte_ip_frag_common.c | 26 +++++++++++++++++++++++++
 4 files changed, 61 insertions(+), 18 deletions(-)

diff --git a/lib/librte_ip_frag/ip_frag_common.h b/lib/librte_ip_frag/ip_frag_common.h
index 197acf8d8..ef869182d 100644
--- a/lib/librte_ip_frag/ip_frag_common.h
+++ b/lib/librte_ip_frag/ip_frag_common.h
@@ -25,6 +25,12 @@
 #define IPv6_KEY_BYTES_FMT \
 	"%08" PRIx64 "%08" PRIx64 "%08" PRIx64 "%08" PRIx64
 
+#ifdef RTE_LIBRTE_IP_FRAG_TBL_STAT
+#define	IP_FRAG_TBL_STAT_UPDATE(s, f, v)	((s)->f += (v))
+#else
+#define	IP_FRAG_TBL_STAT_UPDATE(s, f, v)	do {} while (0)
+#endif /* IP_FRAG_TBL_STAT */
+
 /* internal functions declarations */
 struct rte_mbuf * ip_frag_process(struct ip_frag_pkt *fp,
 		struct rte_ip_frag_death_row *dr, struct rte_mbuf *mb,
@@ -149,4 +155,16 @@ ip_frag_reset(struct ip_frag_pkt *fp, uint64_t tms)
 	fp->frags[IP_FIRST_FRAG_IDX] = zero_frag;
 }
 
+/* frag table helper functions */
+static inline void
+ip_frag_tbl_del(struct rte_ip_frag_tbl *tbl, struct rte_ip_frag_death_row *dr,
+	struct ip_frag_pkt *fp)
+{
+	ip_frag_free(fp, dr);
+	ip_frag_key_invalidate(&fp->key);
+	TAILQ_REMOVE(&tbl->lru, fp, lru);
+	tbl->use_entries--;
+	IP_FRAG_TBL_STAT_UPDATE(&tbl->stat, del_num, 1);
+}
+
 #endif /* _IP_FRAG_COMMON_H_ */
diff --git a/lib/librte_ip_frag/ip_frag_internal.c b/lib/librte_ip_frag/ip_frag_internal.c
index 2560c7713..97470a872 100644
--- a/lib/librte_ip_frag/ip_frag_internal.c
+++ b/lib/librte_ip_frag/ip_frag_internal.c
@@ -14,24 +14,6 @@
 #define	IP_FRAG_TBL_POS(tbl, sig)	\
 	((tbl)->pkt + ((sig) & (tbl)->entry_mask))
 
-#ifdef RTE_LIBRTE_IP_FRAG_TBL_STAT
-#define	IP_FRAG_TBL_STAT_UPDATE(s, f, v)	((s)->f += (v))
-#else
-#define	IP_FRAG_TBL_STAT_UPDATE(s, f, v)	do {} while (0)
-#endif /* IP_FRAG_TBL_STAT */
-
-/* local frag table helper functions */
-static inline void
-ip_frag_tbl_del(struct rte_ip_frag_tbl *tbl, struct rte_ip_frag_death_row *dr,
-	struct ip_frag_pkt *fp)
-{
-	ip_frag_free(fp, dr);
-	ip_frag_key_invalidate(&fp->key);
-	TAILQ_REMOVE(&tbl->lru, fp, lru);
-	tbl->use_entries--;
-	IP_FRAG_TBL_STAT_UPDATE(&tbl->stat, del_num, 1);
-}
-
 static inline void
 ip_frag_tbl_add(struct rte_ip_frag_tbl *tbl,  struct ip_frag_pkt *fp,
 	const struct ip_frag_key *key, uint64_t tms)
diff --git a/lib/librte_ip_frag/rte_ip_frag.h b/lib/librte_ip_frag/rte_ip_frag.h
index b3f3f78df..79443096c 100644
--- a/lib/librte_ip_frag/rte_ip_frag.h
+++ b/lib/librte_ip_frag/rte_ip_frag.h
@@ -146,6 +146,23 @@ struct rte_ip_frag_tbl * rte_ip_frag_table_create(uint32_t bucket_num,
 		uint32_t bucket_entries,  uint32_t max_entries,
 		uint64_t max_cycles, int socket_id);
 
+/**
+ * Sweep the IP fragmentation table for expired segments.
+ *
+ * @param tbl
+ *   Fragmentation table to sweep.
+ * @param dr
+ *   Death row to free buffers to
+ * @param next
+ *   Pointer to the bucket iterator.
+ *   Should be 0 to start sweeping the fragmentation table.
+ *   Bucket iterator is incremented after each call of this function.
+ * @return
+ *   0 if successful. -EINVAL if the parameters are invalid.
+ */
+int rte_ip_frag_sweep_table(struct rte_ip_frag_tbl *tbl,
+	struct rte_ip_frag_death_row *dr, uint32_t *next);
+
 /**
  * Free allocated IP fragmentation table.
  *
diff --git a/lib/librte_ip_frag/rte_ip_frag_common.c b/lib/librte_ip_frag/rte_ip_frag_common.c
index 659a17951..53325ddae 100644
--- a/lib/librte_ip_frag/rte_ip_frag_common.c
+++ b/lib/librte_ip_frag/rte_ip_frag_common.c
@@ -7,6 +7,7 @@
 
 #include <rte_memory.h>
 #include <rte_log.h>
+#include <rte_cycles.h>
 
 #include "ip_frag_common.h"
 
@@ -93,6 +94,31 @@ rte_ip_frag_table_destroy(struct rte_ip_frag_tbl *tbl)
 	rte_free(tbl);
 }
 
+/* Sweep the IP fragmentation table. */
+int
+rte_ip_frag_sweep_table(struct rte_ip_frag_tbl *tbl,
+	struct rte_ip_frag_death_row *dr, uint32_t *next)
+{
+	uint32_t i;
+	uint64_t cur_tsc = rte_rdtsc();
+	struct ip_frag_pkt *pkt;
+
+	if (tbl == NULL || dr == NULL || next == NULL ||
+			(*next * tbl->bucket_entries >= tbl->nb_entries))
+		return -EINVAL;
+
+	pkt = tbl->pkt + *next * tbl->bucket_entries;
+	for (i = 0; i < tbl->bucket_entries; i++) {
+		if (tbl->max_cycles + pkt[i].start < cur_tsc)
+			ip_frag_tbl_del(tbl, dr, pkt + i);
+	}
+
+	*next = (*next + 1) * tbl->bucket_entries >= tbl->nb_entries ?
+		0 : *next + 1;
+
+	return 0;
+}
+
 /* dump frag table statistics to file */
 void
 rte_ip_frag_table_statistics_dump(FILE *f, const struct rte_ip_frag_tbl *tbl)
-- 
2.17.1