[ovs-dev,v6,04/10] Userspace datapath: Add fragmentation handling.

Message ID 1523242444-76467-5-git-send-email-dlu998@gmail.com
State New
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Series
  • Userspace datapath: Add fragmentation support.
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Commit Message

Darrell Ball April 9, 2018, 2:53 a.m.
Fragmentation handling is added for supporting conntrack.
Both v4 and v6 are supported.

After discussion with several people, I decided to not store
configuration state in the database to be more consistent with
the kernel in future, similarity with other conntrack configuration
which will not be in the database as well and overall simplicity.
Accordingly, fragmentation handling is enabled by default.

This patch enables fragmentation tests for the userspace datapath.

Signed-off-by: Darrell Ball <dlu998@gmail.com>
---
 NEWS                         |    2 +
 include/sparse/netinet/ip6.h |    1 +
 lib/automake.mk              |    2 +
 lib/conntrack.c              |    7 +
 lib/ipf.c                    | 1238 ++++++++++++++++++++++++++++++++++++++++++
 lib/ipf.h                    |   63 +++
 tests/system-traffic.at      |   10 -
 7 files changed, 1313 insertions(+), 10 deletions(-)
 create mode 100644 lib/ipf.c
 create mode 100644 lib/ipf.h

Patch

diff --git a/NEWS b/NEWS
index 0cfcac5..2f31680 100644
--- a/NEWS
+++ b/NEWS
@@ -10,6 +10,8 @@  Post-v2.9.0
      * ovs-ofctl now accepts and display table names in place of numbers.  By
        default it always accepts names and in interactive use it displays them;
        use --names or --no-names to override.  See ovs-ofctl(8) for details.
+   - Userspace datapath:
+     * Add v4/v6 fragmentation support for conntrack.
    - ovs-vsctl: New commands "add-bond-iface" and "del-bond-iface".
    - OpenFlow:
      * OFPT_ROLE_STATUS is now available in OpenFlow 1.3.
diff --git a/include/sparse/netinet/ip6.h b/include/sparse/netinet/ip6.h
index d2a54de..bfa637a 100644
--- a/include/sparse/netinet/ip6.h
+++ b/include/sparse/netinet/ip6.h
@@ -64,5 +64,6 @@  struct ip6_frag {
 };
 
 #define IP6F_OFF_MASK ((OVS_FORCE ovs_be16) 0xfff8)
+#define IP6F_MORE_FRAG ((OVS_FORCE ovs_be16) 0x0001)
 
 #endif /* netinet/ip6.h sparse */
diff --git a/lib/automake.mk b/lib/automake.mk
index 915a33b..04163b3 100644
--- a/lib/automake.mk
+++ b/lib/automake.mk
@@ -107,6 +107,8 @@  lib_libopenvswitch_la_SOURCES = \
 	lib/hmapx.h \
 	lib/id-pool.c \
 	lib/id-pool.h \
+	lib/ipf.c \
+	lib/ipf.h \
 	lib/jhash.c \
 	lib/jhash.h \
 	lib/json.c \
diff --git a/lib/conntrack.c b/lib/conntrack.c
index 2b20e93..987c034 100644
--- a/lib/conntrack.c
+++ b/lib/conntrack.c
@@ -30,6 +30,7 @@ 
 #include "ct-dpif.h"
 #include "dp-packet.h"
 #include "flow.h"
+#include "ipf.h"
 #include "netdev.h"
 #include "odp-netlink.h"
 #include "openvswitch/hmap.h"
@@ -340,6 +341,7 @@  conntrack_init(struct conntrack *ct)
     atomic_init(&ct->n_conn_limit, DEFAULT_N_CONN_LIMIT);
     latch_init(&ct->clean_thread_exit);
     ct->clean_thread = ovs_thread_create("ct_clean", clean_thread_main, ct);
+    ipf_init();
 }
 
 /* Destroys the connection tracker 'ct' and frees all the allocated memory. */
@@ -382,6 +384,7 @@  conntrack_destroy(struct conntrack *ct)
     hindex_destroy(&ct->alg_expectation_refs);
     ct_rwlock_unlock(&ct->resources_lock);
     ct_rwlock_destroy(&ct->resources_lock);
+    ipf_destroy();
 }
 
 static unsigned hash_to_bucket(uint32_t hash)
@@ -1308,6 +1311,8 @@  conntrack_execute(struct conntrack *ct, struct dp_packet_batch *pkt_batch,
                   const struct nat_action_info_t *nat_action_info,
                   long long now)
 {
+    ipf_preprocess_conntrack(pkt_batch, now, dl_type, zone, ct->hash_basis);
+
     struct dp_packet *packet;
     struct conn_lookup_ctx ctx;
 
@@ -1321,6 +1326,8 @@  conntrack_execute(struct conntrack *ct, struct dp_packet_batch *pkt_batch,
                     setlabel, nat_action_info, tp_src, tp_dst, helper);
     }
 
+    ipf_postprocess_conntrack(pkt_batch, now, dl_type);
+
     return 0;
 }
 
diff --git a/lib/ipf.c b/lib/ipf.c
new file mode 100644
index 0000000..3837c60
--- /dev/null
+++ b/lib/ipf.c
@@ -0,0 +1,1238 @@ 
+/*
+ * Copyright (c) 2018 Nicira, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <config.h>
+#include <ctype.h>
+#include <errno.h>
+#include <sys/types.h>
+#include <netinet/in.h>
+#include <netinet/ip6.h>
+#include <netinet/icmp6.h>
+#include <string.h>
+
+#include "coverage.h"
+#include "csum.h"
+#include "ipf.h"
+#include "openvswitch/hmap.h"
+#include "openvswitch/vlog.h"
+#include "ovs-atomic.h"
+#include "packets.h"
+#include "util.h"
+
+VLOG_DEFINE_THIS_MODULE(ipf);
+COVERAGE_DEFINE(ipf_stuck_frag_list_purged);
+
+enum {
+    IPV4_PACKET_MAX_HDR_SIZE = 60,
+    IPV4_PACKET_MAX_SIZE = 65535,
+    IPV6_PACKET_MAX_DATA = 65535,
+};
+
+enum ipf_list_state {
+    IPF_LIST_STATE_UNUSED,
+    IPF_LIST_STATE_REASS_FAIL,
+    IPF_LIST_STATE_OTHER_SEEN,
+    IPF_LIST_STATE_FIRST_SEEN,
+    IPF_LIST_STATE_LAST_SEEN,
+    IPF_LIST_STATE_FIRST_LAST_SEEN,
+    IPF_LIST_STATE_COMPLETED,
+    IPF_LIST_STATE_NUM,
+};
+
+enum ipf_list_type {
+    IPF_FRAG_COMPLETED_LIST,
+    IPF_FRAG_EXPIRY_LIST,
+};
+
+enum {
+    IPF_INVALID_IDX = -1,
+    IPF_V4_FRAG_SIZE_LBOUND = 400,
+    IPF_V4_FRAG_SIZE_MIN_DEF = 1200,
+    IPF_V6_FRAG_SIZE_LBOUND = 1280,
+    IPF_V6_FRAG_SIZE_MIN_DEF = 1280,
+    IPF_MAX_FRAGS_DEFAULT = 1000,
+    IPF_NFRAG_UBOUND = 5000,
+};
+
+enum ipf_counter_type {
+    IPF_COUNTER_NFRAGS,
+    IPF_COUNTER_NFRAGS_ACCEPTED,
+    IPF_COUNTER_NFRAGS_COMPL_SENT,
+    IPF_COUNTER_NFRAGS_EXPD_SENT,
+    IPF_COUNTER_NFRAGS_TOO_SMALL,
+    IPF_COUNTER_NFRAGS_OVERLAP,
+};
+
+struct ipf_addr {
+    union {
+        ovs_16aligned_be32 ipv4;
+        union ovs_16aligned_in6_addr ipv6;
+        ovs_be32 ipv4_aligned;
+        struct in6_addr ipv6_aligned;
+    };
+};
+
+struct ipf_frag {
+    struct dp_packet *pkt;
+    uint16_t start_data_byte;
+    uint16_t end_data_byte;
+};
+
+struct ipf_list_key {
+    struct ipf_addr src_addr;
+    struct ipf_addr dst_addr;
+    uint32_t recirc_id;
+    ovs_be32 ip_id;   /* V6 is 32 bits. */
+    ovs_be16 dl_type;
+    uint16_t zone;
+    uint8_t nw_proto;
+};
+
+struct ipf_list {
+    struct hmap_node node;
+    struct ovs_list exp_node;
+    struct ovs_list complete_node;
+    struct ipf_frag *frag_list;
+    struct ipf_list_key key;
+    struct dp_packet *reass_execute_ctx;
+    long long expiration;
+    int last_sent_idx;
+    int last_inuse_idx;
+    int size;
+    uint8_t state;
+};
+
+struct reassembled_pkt {
+    struct ovs_list rp_list_node;
+    struct dp_packet *pkt;
+    struct ipf_list *list;
+};
+
+struct OVS_LOCKABLE ipf_lock {
+    struct ovs_mutex lock;
+};
+
+static int max_v4_frag_list_size;
+
+static struct hmap frag_lists OVS_GUARDED;
+static struct ovs_list frag_exp_list OVS_GUARDED;
+static struct ovs_list frag_complete_list OVS_GUARDED;
+static struct ovs_list reassembled_pkt_list OVS_GUARDED;
+
+static atomic_bool ifp_v4_enabled;
+static atomic_bool ifp_v6_enabled;
+static atomic_uint nfrag_max;
+/* Will be clamped above 400 bytes; the value chosen should handle
+ * alg control packets of interest that use string encoding of mutable
+ * IP fields; meaning, the control packets should not be fragmented. */
+static atomic_uint min_v4_frag_size;
+static atomic_uint min_v6_frag_size;
+
+static atomic_count nfrag;
+static atomic_count n4frag_accepted;
+static atomic_count n4frag_completed_sent;
+static atomic_count n4frag_expired_sent;
+static atomic_count n4frag_too_small;
+static atomic_count n4frag_overlap;
+static atomic_count n6frag_accepted;
+static atomic_count n6frag_completed_sent;
+static atomic_count n6frag_expired_sent;
+static atomic_count n6frag_too_small;
+static atomic_count n6frag_overlap;
+
+static struct ipf_lock ipf_lock;
+
+static void ipf_lock_init(struct ipf_lock *lock)
+{
+    ovs_mutex_init_adaptive(&lock->lock);
+}
+
+static void ipf_lock_lock(struct ipf_lock *lock)
+    OVS_ACQUIRES(lock)
+    OVS_NO_THREAD_SAFETY_ANALYSIS
+{
+    ovs_mutex_lock(&lock->lock);
+}
+
+static void ipf_lock_unlock(struct ipf_lock *lock)
+    OVS_RELEASES(lock)
+    OVS_NO_THREAD_SAFETY_ANALYSIS
+{
+    ovs_mutex_unlock(&lock->lock);
+}
+
+static void ipf_lock_destroy(struct ipf_lock *lock)
+{
+    ovs_mutex_destroy(&lock->lock);
+}
+
+static void
+ipf_count(bool v4, enum ipf_counter_type cntr)
+{
+    if (v4) {
+        switch (cntr) {
+        case IPF_COUNTER_NFRAGS_ACCEPTED:
+            atomic_count_inc(&n4frag_accepted);
+            break;
+        case IPF_COUNTER_NFRAGS_COMPL_SENT:
+            atomic_count_inc(&n4frag_completed_sent);
+            break;
+        case IPF_COUNTER_NFRAGS_EXPD_SENT:
+            atomic_count_inc(&n4frag_expired_sent);
+            break;
+        case IPF_COUNTER_NFRAGS_TOO_SMALL:
+            atomic_count_inc(&n4frag_too_small);
+            break;
+        case IPF_COUNTER_NFRAGS_OVERLAP:
+            atomic_count_inc(&n4frag_overlap);
+            break;
+        case IPF_COUNTER_NFRAGS:
+        default:
+            OVS_NOT_REACHED();
+        }
+    } else {
+        switch (cntr) {
+        case IPF_COUNTER_NFRAGS_ACCEPTED:
+            atomic_count_inc(&n6frag_accepted);
+            break;
+        case IPF_COUNTER_NFRAGS_COMPL_SENT:
+            atomic_count_inc(&n6frag_completed_sent);
+            break;
+        case IPF_COUNTER_NFRAGS_EXPD_SENT:
+            atomic_count_inc(&n6frag_expired_sent);
+            break;
+        case IPF_COUNTER_NFRAGS_TOO_SMALL:
+            atomic_count_inc(&n6frag_too_small);
+            break;
+        case IPF_COUNTER_NFRAGS_OVERLAP:
+            atomic_count_inc(&n6frag_overlap);
+            break;
+        case IPF_COUNTER_NFRAGS:
+        default:
+            OVS_NOT_REACHED();
+        }
+    }
+}
+
+static bool
+ipf_get_enabled(void)
+{
+    bool ifp_v4_enabled_;
+    bool ifp_v6_enabled_;
+    atomic_read_relaxed(&ifp_v4_enabled, &ifp_v4_enabled_);
+    atomic_read_relaxed(&ifp_v6_enabled, &ifp_v6_enabled_);
+    return ifp_v4_enabled_ || ifp_v6_enabled_;
+}
+
+static bool
+ipf_get_v4_enabled(void)
+{
+    bool ifp_v4_enabled_;
+    atomic_read_relaxed(&ifp_v4_enabled, &ifp_v4_enabled_);
+    return ifp_v4_enabled_;
+}
+
+static bool
+ipf_get_v6_enabled(void)
+{
+    bool ifp_v6_enabled_;
+    atomic_read_relaxed(&ifp_v6_enabled, &ifp_v6_enabled_);
+    return ifp_v6_enabled_;
+}
+
+static uint32_t
+ipf_addr_hash_add(uint32_t hash, const struct ipf_addr *addr)
+{
+    BUILD_ASSERT_DECL(sizeof *addr % 4 == 0);
+    return hash_add_bytes32(hash, (const uint32_t *) addr, sizeof *addr);
+}
+
+static void
+ipf_expiry_list_add(struct ipf_list *ipf_list, long long now)
+    OVS_REQUIRES(ipf_lock)
+{
+    enum {
+        IPF_FRAG_LIST_TIMEOUT_DEFAULT = 15000,
+    };
+
+    ipf_list->expiration = now + IPF_FRAG_LIST_TIMEOUT_DEFAULT;
+    ovs_list_push_back(&frag_exp_list, &ipf_list->exp_node);
+}
+
+static void
+ipf_completed_list_add(struct ipf_list *ipf_list)
+    OVS_REQUIRES(ipf_lock)
+{
+    ovs_list_push_back(&frag_complete_list, &ipf_list->complete_node);
+}
+
+static void
+ipf_reassembled_list_add(struct reassembled_pkt *rp)
+    OVS_REQUIRES(ipf_lock)
+{
+    ovs_list_push_back(&reassembled_pkt_list, &rp->rp_list_node);
+}
+
+static void
+ipf_expiry_list_remove(struct ipf_list *ipf_list)
+    OVS_REQUIRES(ipf_lock)
+{
+    ovs_list_remove(&ipf_list->exp_node);
+}
+
+static void
+ipf_completed_list_remove(struct ipf_list *ipf_list)
+    OVS_REQUIRES(ipf_lock)
+{
+    ovs_list_remove(&ipf_list->complete_node);
+}
+
+static void
+ipf_reassembled_list_remove(struct reassembled_pkt *rp)
+    OVS_REQUIRES(ipf_lock)
+{
+    ovs_list_remove(&rp->rp_list_node);
+}
+
+/* Symmetric */
+static uint32_t
+ipf_list_key_hash(const struct ipf_list_key *key, uint32_t basis)
+{
+    uint32_t hsrc, hdst, hash;
+    hsrc = hdst = basis;
+    hsrc = ipf_addr_hash_add(hsrc, &key->src_addr);
+    hdst = ipf_addr_hash_add(hdst, &key->dst_addr);
+    hash = hsrc ^ hdst;
+
+    /* Hash the rest of the key. */
+    hash = hash_words((uint32_t *) (&key->dst_addr + 1),
+                      (uint32_t *) (key + 1) -
+                          (uint32_t *) (&key->dst_addr + 1),
+                      hash);
+
+    return hash_finish(hash, 0);
+}
+
+static bool
+ipf_is_first_v4_frag(const struct dp_packet *pkt)
+{
+    const struct ip_header *l3 = dp_packet_l3(pkt);
+    if (!(l3->ip_frag_off & htons(IP_FRAG_OFF_MASK)) &&
+        l3->ip_frag_off & htons(IP_MORE_FRAGMENTS)) {
+        return true;
+    }
+    return false;
+}
+
+static bool
+ipf_is_last_v4_frag(const struct dp_packet *pkt)
+{
+    const struct ip_header *l3 = dp_packet_l3(pkt);
+    if (l3->ip_frag_off & htons(IP_FRAG_OFF_MASK) &&
+        !(l3->ip_frag_off & htons(IP_MORE_FRAGMENTS))) {
+        return true;
+    }
+    return false;
+}
+
+static bool
+ipf_is_v6_frag(ovs_be16 ip6f_offlg)
+{
+    if (ip6f_offlg & (IP6F_OFF_MASK | IP6F_MORE_FRAG)) {
+        return true;
+    }
+    return false;
+}
+
+static bool
+ipf_is_first_v6_frag(ovs_be16 ip6f_offlg)
+{
+    if (!(ip6f_offlg & IP6F_OFF_MASK) &&
+        ip6f_offlg & IP6F_MORE_FRAG) {
+        return true;
+    }
+    return false;
+}
+
+static bool
+ipf_is_last_v6_frag(ovs_be16 ip6f_offlg)
+{
+    if ((ip6f_offlg & IP6F_OFF_MASK) &&
+        !(ip6f_offlg & IP6F_MORE_FRAG)) {
+        return true;
+    }
+    return false;
+}
+
+static bool
+ipf_list_complete(const struct ipf_list *ipf_list)
+    OVS_REQUIRES(ipf_lock)
+{
+    for (int i = 0; i < ipf_list->last_inuse_idx; i++) {
+        if (ipf_list->frag_list[i].end_data_byte + 1
+            != ipf_list->frag_list[i + 1].start_data_byte) {
+            return false;
+        }
+    }
+    return true;
+}
+
+/* Runs O(n) for a sorted or almost sorted list. */
+static void
+ipf_sort(struct ipf_frag *frag_list, size_t last_idx)
+    OVS_REQUIRES(ipf_lock)
+{
+    int running_last_idx = 1;
+    struct ipf_frag ipf_frag;
+    while (running_last_idx <= last_idx) {
+        ipf_frag = frag_list[running_last_idx];
+        int frag_list_idx = running_last_idx - 1;
+        while (frag_list_idx >= 0 &&
+               frag_list[frag_list_idx].start_data_byte >
+                   ipf_frag.start_data_byte) {
+            frag_list[frag_list_idx + 1] = frag_list[frag_list_idx];
+            frag_list_idx -= 1;
+        }
+        frag_list[frag_list_idx + 1] = ipf_frag;
+        running_last_idx++;
+    }
+}
+
+/* Called on a sorted complete list of fragments. */
+static struct dp_packet *
+ipf_reassemble_v4_frags(struct ipf_list *ipf_list)
+    OVS_REQUIRES(ipf_lock)
+{
+    struct ipf_frag *frag_list = ipf_list->frag_list;
+    struct dp_packet *pkt = dp_packet_clone(frag_list[0].pkt);
+    struct ip_header *l3 = dp_packet_l3(pkt);
+    int len = ntohs(l3->ip_tot_len);
+    size_t add_len;
+    size_t ip_hdr_len = IP_IHL(l3->ip_ihl_ver) * 4;
+
+    for (int i = 1; i <= ipf_list->last_inuse_idx; i++) {
+        add_len = frag_list[i].end_data_byte -
+                         frag_list[i].start_data_byte + 1;
+        len += add_len;
+        if (len > IPV4_PACKET_MAX_SIZE) {
+            dp_packet_delete(pkt);
+            return NULL;
+        }
+        l3 = dp_packet_l3(frag_list[i].pkt);
+        dp_packet_put(pkt, (char *)l3 + ip_hdr_len, add_len);
+    }
+    l3 = dp_packet_l3(pkt);
+    ovs_be16 new_ip_frag_off = l3->ip_frag_off & ~htons(IP_MORE_FRAGMENTS);
+    l3->ip_csum = recalc_csum16(l3->ip_csum, l3->ip_frag_off,
+                                new_ip_frag_off);
+    l3->ip_csum = recalc_csum16(l3->ip_csum, l3->ip_tot_len, htons(len));
+    l3->ip_tot_len = htons(len);
+    l3->ip_frag_off = new_ip_frag_off;
+
+    return pkt;
+}
+
+/* Called on a sorted complete list of fragments. */
+static struct dp_packet *
+ipf_reassemble_v6_frags(struct ipf_list *ipf_list)
+    OVS_REQUIRES(ipf_lock)
+{
+    struct ipf_frag *frag_list = ipf_list->frag_list;
+    struct dp_packet *pkt = dp_packet_clone(frag_list[0].pkt);
+    struct  ovs_16aligned_ip6_hdr *l3 = dp_packet_l3(pkt);
+    int pl = ntohs(l3->ip6_plen) - sizeof(struct ovs_16aligned_ip6_frag);
+    const char *tail = dp_packet_tail(pkt);
+    uint8_t pad = dp_packet_l2_pad_size(pkt);
+    const char *l4 = dp_packet_l4(pkt);
+    size_t l3_size = tail - (char *)l3 -pad;
+    size_t l4_size = tail - (char *)l4 -pad;
+    size_t l3_hlen = l3_size - l4_size;
+    size_t add_len;
+
+    for (int i = 1; i <= ipf_list->last_inuse_idx; i++) {
+        add_len = frag_list[i].end_data_byte -
+                          frag_list[i].start_data_byte + 1;
+        pl += add_len;
+        if (pl > IPV6_PACKET_MAX_DATA) {
+            dp_packet_delete(pkt);
+            return NULL;
+        }
+        l3 = dp_packet_l3(frag_list[i].pkt);
+        dp_packet_put(pkt, (char *)l3 + l3_hlen, add_len);
+    }
+    l3 = dp_packet_l3(pkt);
+    l4 = dp_packet_l4(pkt);
+    tail = dp_packet_tail(pkt);
+    pad = dp_packet_l2_pad_size(pkt);
+    l3_size = tail - (char *)l3 -pad;
+
+    uint8_t nw_proto = l3->ip6_nxt;
+    uint8_t nw_frag = 0;
+    const void *data = l3 + 1;
+    size_t datasize = l3_size - sizeof *l3;
+
+    const struct ovs_16aligned_ip6_frag *frag_hdr = NULL;
+    if (!parse_ipv6_ext_hdrs(&data, &datasize, &nw_proto, &nw_frag, &frag_hdr)
+        || !nw_frag || !frag_hdr) {
+        return NULL;
+    }
+
+    struct ovs_16aligned_ip6_frag *fh =
+        CONST_CAST(struct ovs_16aligned_ip6_frag *, frag_hdr);
+    fh->ip6f_offlg = 0;;
+    l3->ip6_plen = htons(pl);
+    l3->ip6_ctlun.ip6_un1.ip6_un1_nxt = nw_proto;
+    return pkt;
+}
+
+/* Called when a valid fragment is added. */
+static void
+ipf_list_state_transition(struct ipf_list *ipf_list, bool ff, bool lf,
+                          bool v4)
+    OVS_REQUIRES(ipf_lock)
+{
+    enum ipf_list_state curr_state = ipf_list->state;
+    enum ipf_list_state next_state;
+    switch (curr_state) {
+    case IPF_LIST_STATE_UNUSED:
+    case IPF_LIST_STATE_OTHER_SEEN:
+        if (ff) {
+            next_state = IPF_LIST_STATE_FIRST_SEEN;
+        } else if (lf) {
+            next_state = IPF_LIST_STATE_LAST_SEEN;
+        } else {
+            next_state = IPF_LIST_STATE_OTHER_SEEN;
+        }
+        break;
+    case IPF_LIST_STATE_FIRST_SEEN:
+        if (ff) {
+            next_state = IPF_LIST_STATE_FIRST_SEEN;
+        } else if (lf) {
+            next_state = IPF_LIST_STATE_FIRST_LAST_SEEN;
+        } else {
+            next_state = IPF_LIST_STATE_FIRST_SEEN;
+        }
+        break;
+    case IPF_LIST_STATE_LAST_SEEN:
+        if (ff) {
+            next_state = IPF_LIST_STATE_FIRST_LAST_SEEN;
+        } else if (lf) {
+            next_state = IPF_LIST_STATE_LAST_SEEN;
+        } else {
+            next_state = IPF_LIST_STATE_LAST_SEEN;
+        }
+        break;
+    case IPF_LIST_STATE_FIRST_LAST_SEEN:
+        next_state = IPF_LIST_STATE_FIRST_LAST_SEEN;
+        ipf_sort(ipf_list->frag_list, ipf_list->last_inuse_idx);
+        break;
+    case IPF_LIST_STATE_COMPLETED:
+        next_state = curr_state;
+        break;
+    case IPF_LIST_STATE_REASS_FAIL:
+    case IPF_LIST_STATE_NUM:
+    default:
+        OVS_NOT_REACHED();
+    }
+
+    if (next_state == IPF_LIST_STATE_FIRST_LAST_SEEN &&
+        ipf_list_complete(ipf_list)) {
+        struct dp_packet *reass_pkt = NULL;
+        if (v4) {
+            reass_pkt = ipf_reassemble_v4_frags(ipf_list);
+        } else {
+            reass_pkt = ipf_reassemble_v6_frags(ipf_list);
+        }
+        if (reass_pkt) {
+            struct reassembled_pkt *rp = xzalloc(sizeof *rp);
+            rp->pkt = reass_pkt;
+            rp->list = ipf_list;
+            ipf_reassembled_list_add(rp);
+            ipf_expiry_list_remove(ipf_list);
+            next_state = IPF_LIST_STATE_COMPLETED;
+        } else {
+            next_state = IPF_LIST_STATE_REASS_FAIL;
+        }
+    }
+    ipf_list->state = next_state;
+}
+
+static bool
+ipf_v4_key_extract(const struct dp_packet *pkt, ovs_be16 dl_type,
+                   uint16_t zone, struct ipf_list_key *key,
+                   uint16_t *start_data_byte, uint16_t *end_data_byte,
+                   bool *ff, bool *lf)
+{
+    if (dp_packet_ip_checksum_bad(pkt)) {
+        return false;
+    }
+
+    const struct eth_header *l2 = dp_packet_eth(pkt);
+    const struct ip_header *l3 = dp_packet_l3(pkt);
+
+    if (!l2 || !l3) {
+        return false;
+    }
+
+    const char *tail = dp_packet_tail(pkt);
+    uint8_t pad = dp_packet_l2_pad_size(pkt);
+    size_t size = tail - (char *)l3 -pad;
+    if (OVS_UNLIKELY(size < IP_HEADER_LEN)) {
+        return false;
+    }
+
+    uint16_t ip_tot_len = ntohs(l3->ip_tot_len);
+    if (ip_tot_len != size) {
+        return false;
+    }
+
+    if (!(IP_IS_FRAGMENT(l3->ip_frag_off))) {
+        return false;
+    }
+
+    size_t ip_hdr_len = IP_IHL(l3->ip_ihl_ver) * 4;
+    if (OVS_UNLIKELY(ip_hdr_len < IP_HEADER_LEN)) {
+        return false;
+    }
+    if (OVS_UNLIKELY(size < ip_hdr_len)) {
+        return false;
+    }
+
+    if (!dp_packet_ip_checksum_valid(pkt) && csum(l3, ip_hdr_len) != 0) {
+        return false;
+    }
+
+    uint32_t min_v4_frag_size_;
+    atomic_read_relaxed(&min_v4_frag_size, &min_v4_frag_size_);
+    *lf = ipf_is_last_v4_frag(pkt);
+    if (!*lf && dp_packet_size(pkt) <= min_v4_frag_size_) {
+        ipf_count(true, IPF_COUNTER_NFRAGS_TOO_SMALL);
+        return false;
+    }
+
+    *start_data_byte = ntohs(l3->ip_frag_off & htons(IP_FRAG_OFF_MASK)) * 8;
+    *end_data_byte = *start_data_byte + ip_tot_len - ip_hdr_len - 1;
+    *ff = ipf_is_first_v4_frag(pkt);
+    memset(key, 0, sizeof *key);
+    key->ip_id = be16_to_be32(l3->ip_id);
+    key->dl_type = dl_type;
+    key->src_addr.ipv4 = l3->ip_src;
+    key->dst_addr.ipv4 = l3->ip_dst;
+    key->nw_proto = l3->ip_proto;
+    key->zone = zone;
+    key->recirc_id = pkt->md.recirc_id;
+    return true;
+}
+
+static bool
+ipf_v6_key_extract(const struct dp_packet *pkt, ovs_be16 dl_type,
+                uint16_t zone, struct ipf_list_key *key,
+                uint16_t *start_data_byte, uint16_t *end_data_byte,
+                bool *ff, bool *lf)
+{
+    const struct eth_header *l2 = dp_packet_eth(pkt);
+    const struct  ovs_16aligned_ip6_hdr *l3 = dp_packet_l3(pkt);
+    const char *l4 = dp_packet_l4(pkt);
+
+    if (!l2 || !l3 || !l4) {
+        return false;
+    }
+
+    const char *tail = dp_packet_tail(pkt);
+    uint8_t pad = dp_packet_l2_pad_size(pkt);
+    size_t l3_size = tail - (char *)l3 -pad;
+    size_t l4_size = tail - (char *)l4 -pad;
+    size_t l3_hdr_size = sizeof *l3;
+
+    if (OVS_UNLIKELY(l3_size < l3_hdr_size)) {
+        return false;
+    }
+
+    int pl = ntohs(l3->ip6_plen);
+    if (pl + l3_hdr_size != l3_size) {
+        return false;
+    }
+
+    uint8_t nw_frag = 0;
+    uint8_t nw_proto = l3->ip6_nxt;
+    const void *data = l3 + 1;
+    size_t datasize = l3_size - l3_hdr_size;
+    const struct ovs_16aligned_ip6_frag *frag_hdr = NULL;
+    if (!parse_ipv6_ext_hdrs(&data, &datasize, &nw_proto, &nw_frag,
+                             &frag_hdr) || !nw_frag || !frag_hdr) {
+        return false;
+    }
+
+    ovs_be16 ip6f_offlg = frag_hdr->ip6f_offlg;
+
+    if (!(ipf_is_v6_frag(ip6f_offlg))) {
+        return false;
+    }
+
+    uint32_t min_v6_frag_size_;
+    atomic_read_relaxed(&min_v6_frag_size, &min_v6_frag_size_);
+    *lf = ipf_is_last_v6_frag(ip6f_offlg);
+
+    if (!(*lf) && dp_packet_size(pkt) <= min_v6_frag_size_) {
+        ipf_count(false, IPF_COUNTER_NFRAGS_TOO_SMALL);
+        return false;
+    }
+
+    *start_data_byte = ntohs(ip6f_offlg & IP6F_OFF_MASK) +
+        sizeof (struct ovs_16aligned_ip6_frag);
+    *end_data_byte = *start_data_byte + l4_size - 1;
+    *ff = ipf_is_first_v6_frag(ip6f_offlg);
+    memset(key, 0, sizeof *key);
+    key->ip_id = get_16aligned_be32(&frag_hdr->ip6f_ident);
+    key->dl_type = dl_type;
+    key->src_addr.ipv6 = l3->ip6_src;
+    /* We are not supporting parsing of the routing header header
+     * to use as the dst address part of the key. */
+    key->dst_addr.ipv6 = l3->ip6_dst;
+    /* Not used for key for V6. */
+    key->nw_proto = 0;
+    key->zone = zone;
+    key->recirc_id = pkt->md.recirc_id;
+    return true;
+}
+
+static int
+ipf_list_key_cmp(const struct ipf_list_key *key1,
+                 const struct ipf_list_key *key2)
+    OVS_REQUIRES(ipf_lock)
+{
+    if (!memcmp(&key1->src_addr, &key2->src_addr, sizeof key1->src_addr) &&
+        !memcmp(&key1->dst_addr, &key2->dst_addr, sizeof key1->dst_addr) &&
+        (key1->dl_type == key2->dl_type) &&
+        (key1->ip_id == key2->ip_id) &&
+        (key1->zone == key2->zone) &&
+        (key1->nw_proto == key2->nw_proto) &&
+        (key1->recirc_id == key2->recirc_id)) {
+        return 0;
+    }
+    return 1;
+}
+
+static struct ipf_list *
+ipf_list_key_lookup(const struct ipf_list_key *key,
+                    uint32_t hash)
+    OVS_REQUIRES(ipf_lock)
+{
+    struct ipf_list *ipf_list;
+    HMAP_FOR_EACH_WITH_HASH (ipf_list, node, hash, &frag_lists) {
+        if (!ipf_list_key_cmp(&ipf_list->key, key)) {
+            return ipf_list;
+        }
+    }
+    return NULL;
+}
+
+static bool
+ipf_is_frag_duped(const struct ipf_frag *frag_list, int last_inuse_idx,
+                  size_t start_data_byte, size_t end_data_byte)
+    OVS_REQUIRES(ipf_lock)
+{
+    for (int i = 0; i <= last_inuse_idx; i++) {
+        if (((start_data_byte >= frag_list[i].start_data_byte) &&
+            (start_data_byte <= frag_list[i].end_data_byte)) ||
+            ((end_data_byte >= frag_list[i].start_data_byte) &&
+             (end_data_byte <= frag_list[i].end_data_byte))) {
+            return true;
+        }
+    }
+    return false;
+}
+
+static bool
+ipf_process_frag(struct ipf_list *ipf_list, struct dp_packet *pkt,
+                 uint16_t start_data_byte, uint16_t end_data_byte,
+                 bool ff, bool lf, bool v4)
+    OVS_REQUIRES(ipf_lock)
+{
+    bool duped_frag = ipf_is_frag_duped(ipf_list->frag_list,
+        ipf_list->last_inuse_idx, start_data_byte, end_data_byte);
+    int last_inuse_idx = ipf_list->last_inuse_idx;
+
+    if (!duped_frag) {
+        if (last_inuse_idx < ipf_list->size - 1) {
+            /* In the case of dpdk, it would be unfortunate if we had
+             * to create a clone fragment outside the dpdk mp due to the
+             * mempool size being too limited. We will otherwise need to
+             * recommend not setting the mempool number of buffers too low
+             * and also clamp the number of fragments. */
+            ipf_list->frag_list[last_inuse_idx + 1].pkt = pkt;
+            ipf_list->frag_list[last_inuse_idx + 1].start_data_byte =
+                start_data_byte;
+            ipf_list->frag_list[last_inuse_idx + 1].end_data_byte =
+                end_data_byte;
+            ipf_list->last_inuse_idx++;
+            atomic_count_inc(&nfrag);
+            ipf_count(v4, IPF_COUNTER_NFRAGS_ACCEPTED);
+            ipf_list_state_transition(ipf_list, ff, lf, v4);
+        } else {
+            OVS_NOT_REACHED();
+        }
+    } else {
+        ipf_count(v4, IPF_COUNTER_NFRAGS_OVERLAP);
+        pkt->md.ct_state = CS_INVALID;
+        return false;
+    }
+    return true;
+}
+
+static bool
+ipf_handle_frag(struct dp_packet *pkt, ovs_be16 dl_type, uint16_t zone,
+                long long now, uint32_t hash_basis)
+    OVS_REQUIRES(ipf_lock)
+{
+    struct ipf_list_key key;
+    uint16_t start_data_byte;
+    uint16_t end_data_byte;
+    bool ff;
+    bool lf;
+    bool v4;
+
+    if (dl_type == htons(ETH_TYPE_IP) && ipf_get_v4_enabled()) {
+        if (!ipf_v4_key_extract(pkt, dl_type, zone, &key, &start_data_byte,
+                &end_data_byte, &ff, &lf)) {
+            return false;
+        }
+        v4 = true;
+    } else if (dl_type == htons(ETH_TYPE_IPV6) && ipf_get_v6_enabled()) {
+        if (!ipf_v6_key_extract(pkt, dl_type, zone, &key, &start_data_byte,
+                &end_data_byte, &ff, &lf)) {
+            return false;
+        }
+        v4 = false;
+    } else {
+        return false;
+    }
+
+    unsigned int nfrag_max_;
+    atomic_read_relaxed(&nfrag_max, &nfrag_max_);
+    if (atomic_count_get(&nfrag) >= nfrag_max_) {
+        return false;
+    }
+
+    uint32_t hash = ipf_list_key_hash(&key, hash_basis);
+    struct ipf_list *ipf_list =
+        ipf_list_key_lookup(&key, hash);
+    enum {
+        IPF_FRAG_LIST_MIN_INCREMENT = 4,
+        IPF_UNBOUNDED_FRAG_LIST_SIZE = 65535,
+    };
+
+    int max_frag_list_size;
+    if (v4) {
+        max_frag_list_size = max_v4_frag_list_size;
+    } else {
+        max_frag_list_size = IPF_UNBOUNDED_FRAG_LIST_SIZE;
+    }
+
+    if (!ipf_list) {
+        ipf_list = xzalloc(sizeof *ipf_list);
+        ipf_list->key = key;
+        ipf_list->last_inuse_idx = IPF_INVALID_IDX;
+        ipf_list->last_sent_idx = IPF_INVALID_IDX;
+        ipf_list->size =
+            MIN(max_frag_list_size, IPF_FRAG_LIST_MIN_INCREMENT);
+        ipf_list->frag_list =
+            xzalloc(ipf_list->size * sizeof *ipf_list->frag_list);
+        hmap_insert(&frag_lists, &ipf_list->node, hash);
+        ipf_expiry_list_add(ipf_list, now);
+    } else if (ipf_list->state == IPF_LIST_STATE_REASS_FAIL) {
+        /* Bail out as early as possible. */
+        return false;
+    } else if (ipf_list->last_inuse_idx + 1 >= ipf_list->size) {
+        int increment = MIN(IPF_FRAG_LIST_MIN_INCREMENT,
+                            max_frag_list_size - ipf_list->size);
+        /* Enforce limit. */
+        if (increment > 0) {
+            ipf_list->frag_list =
+                xrealloc(ipf_list->frag_list, (ipf_list->size + increment) *
+                  sizeof *ipf_list->frag_list);
+            ipf_list->size += increment;
+        } else {
+            return false;
+        }
+    }
+
+    return ipf_process_frag(ipf_list, pkt, start_data_byte, end_data_byte, ff,
+                            lf, v4);
+}
+
+/* Handles V4 fragments right now. */
+static void
+ipf_extract_frags_from_batch(struct dp_packet_batch *pb, ovs_be16 dl_type,
+                             uint16_t zone, long long now, uint32_t hash_basis)
+{
+    const size_t pb_cnt = dp_packet_batch_size(pb);
+    int pb_idx; /* Index in a packet batch. */
+    struct dp_packet *pkt;
+
+    DP_PACKET_BATCH_REFILL_FOR_EACH (pb_idx, pb_cnt, pkt, pb) {
+        ipf_lock_lock(&ipf_lock);
+
+        if (!ipf_handle_frag(pkt, dl_type, zone, now, hash_basis)) {
+            dp_packet_batch_refill(pb, pkt, pb_idx);
+        }
+
+        ipf_lock_unlock(&ipf_lock);
+    }
+}
+
+/* In case of DPDK, a memory source check is done, as DPDK memory pool
+ * management has trouble dealing with multiple source types.  The
+ * check_source paramater is used to indicate when this check is needed. */
+static bool
+ipf_dp_packet_batch_add(struct dp_packet_batch *pb , struct dp_packet *pkt,
+                        bool check_source OVS_UNUSED)
+    OVS_REQUIRES(ipf_lock)
+{
+#ifdef DPDK_NETDEV
+    if ((pb->count >= NETDEV_MAX_BURST) ||
+        /* DPDK cannot handle multiple sources in a batch. */
+        (check_source && pb->count && pb->packets[0]->source != pkt->source)) {
+#else
+    if (pb->count >= NETDEV_MAX_BURST) {
+#endif
+        return false;
+    }
+
+    dp_packet_batch_add(pb, pkt);
+    return true;
+}
+
+/* This would be used in a rare case where a list cannot be sent. The only
+ * reason known right now is a mempool source check,which exists due to DPDK
+ * support, where packets are no longer being received on any port with a
+ * source matching the fragment.
+ * Returns true if the list was purged. */
+static bool
+ipf_purge_list_check(struct ipf_list *ipf_list, long long now)
+    OVS_REQUIRES(ipf_lock)
+{
+    enum {
+        /* 10 minutes. */
+        IPF_FRAG_LIST_TIMEOUT_PURGE = 600000,
+    };
+
+    if (now < ipf_list->expiration + IPF_FRAG_LIST_TIMEOUT_PURGE) {
+        return false;
+    }
+
+    struct dp_packet *pkt;
+    while (ipf_list->last_sent_idx < ipf_list->last_inuse_idx) {
+        pkt = ipf_list->frag_list[ipf_list->last_sent_idx + 1].pkt;
+        dp_packet_delete(pkt);
+        atomic_count_dec(&nfrag);
+        ipf_list->last_sent_idx++;
+    }
+
+    static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 5);
+    VLOG_WARN_RL(&rl, "Fragments dropped due to stuck fragment list purge.");
+    COVERAGE_INC(ipf_stuck_frag_list_purged);
+    return true;
+}
+
+static bool
+ipf_send_frags_in_list(struct ipf_list *ipf_list, struct dp_packet_batch *pb,
+                       enum ipf_list_type list_type, bool v4, long long now)
+    OVS_REQUIRES(ipf_lock)
+{
+    if (ipf_purge_list_check(ipf_list, now)) {
+        return true;
+    }
+
+    struct dp_packet *pkt;
+    while (ipf_list->last_sent_idx < ipf_list->last_inuse_idx) {
+        pkt = ipf_list->frag_list[ipf_list->last_sent_idx + 1].pkt;
+        if (ipf_dp_packet_batch_add(pb, pkt, true)) {
+
+            ipf_list->last_sent_idx++;
+            atomic_count_dec(&nfrag);
+
+            if (list_type == IPF_FRAG_COMPLETED_LIST) {
+                ipf_count(v4, IPF_COUNTER_NFRAGS_COMPL_SENT);
+            } else {
+                ipf_count(v4, IPF_COUNTER_NFRAGS_EXPD_SENT);
+                pkt->md.ct_state = CS_INVALID;
+            }
+
+            if (ipf_list->last_sent_idx == ipf_list->last_inuse_idx) {
+                return true;
+            }
+        } else {
+            return false;
+        }
+    }
+    OVS_NOT_REACHED();
+}
+
+static void
+ipf_list_remove(struct ipf_list *ipf_list, enum ipf_list_type list_type)
+    OVS_REQUIRES(ipf_lock)
+{
+    if (list_type == IPF_FRAG_COMPLETED_LIST) {
+        ipf_completed_list_remove(ipf_list);
+    } else {
+        ipf_expiry_list_remove(ipf_list);
+    }
+    hmap_remove(&frag_lists, &ipf_list->node);
+    free(ipf_list->frag_list);
+    free(ipf_list);
+}
+
+static void
+ipf_send_completed_frags(struct dp_packet_batch *pb, long long now, bool v4)
+{
+    if (ovs_list_is_empty(&frag_complete_list)) {
+        return;
+    }
+
+    ipf_lock_lock(&ipf_lock);
+    struct ipf_list *ipf_list, *next;
+
+    LIST_FOR_EACH_SAFE (ipf_list, next, complete_node, &frag_complete_list) {
+        if (ipf_send_frags_in_list(ipf_list, pb, IPF_FRAG_COMPLETED_LIST,
+                                   v4, now)) {
+            ipf_list_remove(ipf_list, IPF_FRAG_COMPLETED_LIST);
+        } else {
+            break;
+        }
+    }
+    ipf_lock_unlock(&ipf_lock);
+}
+
+static void
+ipf_send_expired_frags(struct dp_packet_batch *pb, long long now, bool v4)
+{
+    enum {
+        /* Very conservative, due to DOS probability. */
+        IPF_FRAG_LIST_MAX_EXPIRED = 1,
+    };
+
+
+    if (ovs_list_is_empty(&frag_exp_list)) {
+        return;
+    }
+
+    ipf_lock_lock(&ipf_lock);
+    struct ipf_list *ipf_list, *next;
+    size_t lists_removed = 0;
+
+    LIST_FOR_EACH_SAFE (ipf_list, next, exp_node, &frag_exp_list) {
+        if (!(now > ipf_list->expiration) ||
+            lists_removed >= IPF_FRAG_LIST_MAX_EXPIRED) {
+            break;
+        }
+
+        if (ipf_send_frags_in_list(ipf_list, pb, IPF_FRAG_EXPIRY_LIST, v4,
+                                   now)) {
+            ipf_list_remove(ipf_list, IPF_FRAG_EXPIRY_LIST);
+            lists_removed++;
+        } else {
+            break;
+        }
+    }
+    ipf_lock_unlock(&ipf_lock);
+}
+
+static void
+ipf_execute_reass_pkts(struct dp_packet_batch *pb)
+{
+    if (ovs_list_is_empty(&reassembled_pkt_list)) {
+        return;
+    }
+
+    ipf_lock_lock(&ipf_lock);
+    struct reassembled_pkt *rp, *next;
+
+    LIST_FOR_EACH_SAFE (rp, next, rp_list_node, &reassembled_pkt_list) {
+        if (!rp->list->reass_execute_ctx &&
+            ipf_dp_packet_batch_add(pb, rp->pkt, false)) {
+            rp->list->reass_execute_ctx = rp->pkt;
+        }
+    }
+    ipf_lock_unlock(&ipf_lock);
+}
+
+static void
+ipf_post_execute_reass_pkts(struct dp_packet_batch *pb, bool v4)
+{
+    if (ovs_list_is_empty(&reassembled_pkt_list)) {
+        return;
+    }
+
+    ipf_lock_lock(&ipf_lock);
+    struct reassembled_pkt *rp, *next;
+
+    LIST_FOR_EACH_SAFE (rp, next, rp_list_node, &reassembled_pkt_list) {
+        const size_t pb_cnt = dp_packet_batch_size(pb);
+        int pb_idx;
+        struct dp_packet *pkt;
+        /* Inner batch loop is constant time since batch size is <=
+         * NETDEV_MAX_BURST. */
+        DP_PACKET_BATCH_REFILL_FOR_EACH (pb_idx, pb_cnt, pkt, pb) {
+            if (pkt == rp->list->reass_execute_ctx) {
+                for (int i = 0; i <= rp->list->last_inuse_idx; i++) {
+                    rp->list->frag_list[i].pkt->md.ct_label = pkt->md.ct_label;
+                    rp->list->frag_list[i].pkt->md.ct_mark = pkt->md.ct_mark;
+                    rp->list->frag_list[i].pkt->md.ct_state = pkt->md.ct_state;
+                    rp->list->frag_list[i].pkt->md.ct_zone = pkt->md.ct_zone;
+                    rp->list->frag_list[i].pkt->md.ct_orig_tuple_ipv6 =
+                        pkt->md.ct_orig_tuple_ipv6;
+                    if (pkt->md.ct_orig_tuple_ipv6) {
+                        rp->list->frag_list[i].pkt->md.ct_orig_tuple.ipv6 =
+                            pkt->md.ct_orig_tuple.ipv6;
+                    } else {
+                        rp->list->frag_list[i].pkt->md.ct_orig_tuple.ipv4  =
+                            pkt->md.ct_orig_tuple.ipv4;
+                    }
+                }
+
+                const char *tail_frag =
+                    dp_packet_tail(rp->list->frag_list[0].pkt);
+                uint8_t pad_frag =
+                    dp_packet_l2_pad_size(rp->list->frag_list[0].pkt);
+
+                void *l4_frag = dp_packet_l4(rp->list->frag_list[0].pkt);
+                void *l4_reass = dp_packet_l4(pkt);
+                memcpy(l4_frag, l4_reass,
+                       tail_frag - (char *) l4_frag - pad_frag);
+
+                if (v4) {
+                    struct ip_header *l3_frag =
+                        dp_packet_l3(rp->list->frag_list[0].pkt);
+                    struct ip_header *l3_reass = dp_packet_l3(pkt);
+                    ovs_be32 reass_ip = get_16aligned_be32(&l3_reass->ip_src);
+                    ovs_be32 frag_ip = get_16aligned_be32(&l3_frag->ip_src);
+                    l3_frag->ip_csum = recalc_csum32(l3_frag->ip_csum,
+                                                 frag_ip, reass_ip);
+                    l3_frag->ip_src = l3_reass->ip_src;
+
+                    reass_ip = get_16aligned_be32(&l3_reass->ip_dst);
+                    frag_ip = get_16aligned_be32(&l3_frag->ip_dst);
+                    l3_frag->ip_csum = recalc_csum32(l3_frag->ip_csum,
+                                                     frag_ip, reass_ip);
+                    l3_frag->ip_dst = l3_reass->ip_dst;
+                } else {
+                    struct  ovs_16aligned_ip6_hdr *l3_frag =
+                        dp_packet_l3(rp->list->frag_list[0].pkt);
+                    struct  ovs_16aligned_ip6_hdr *l3_reass =
+                        dp_packet_l3(pkt);
+                    l3_frag->ip6_src = l3_reass->ip6_src;
+                    l3_frag->ip6_dst = l3_reass->ip6_dst;
+                }
+
+                ipf_completed_list_add(rp->list);
+                ipf_reassembled_list_remove(rp);
+                dp_packet_delete(rp->pkt);
+                free(rp);
+            } else {
+                dp_packet_batch_refill(pb, pkt, pb_idx);
+            }
+        }
+    }
+    ipf_lock_unlock(&ipf_lock);
+}
+
+void
+ipf_preprocess_conntrack(struct dp_packet_batch *pb, long long now,
+                         ovs_be16 dl_type, uint16_t zone, uint32_t hash_basis)
+{
+    if (ipf_get_enabled()) {
+        ipf_extract_frags_from_batch(pb, dl_type, zone, now, hash_basis);
+    }
+
+    if (ipf_get_enabled() || atomic_count_get(&nfrag)) {
+        ipf_execute_reass_pkts(pb);
+    }
+}
+
+void
+ipf_postprocess_conntrack(struct dp_packet_batch *pb, long long now,
+                          ovs_be16 dl_type)
+{
+    if (ipf_get_enabled() || atomic_count_get(&nfrag)) {
+        ipf_post_execute_reass_pkts(pb, dl_type == htons(ETH_TYPE_IP));
+        ipf_send_completed_frags(pb, dl_type == htons(ETH_TYPE_IP), now);
+        ipf_send_expired_frags(pb, now, dl_type == htons(ETH_TYPE_IP));
+    }
+}
+
+void
+ipf_init(void)
+{
+    ipf_lock_init(&ipf_lock);
+    ipf_lock_lock(&ipf_lock);
+    hmap_init(&frag_lists);
+    ovs_list_init(&frag_exp_list);
+    ovs_list_init(&frag_complete_list);
+    ovs_list_init(&reassembled_pkt_list);
+    atomic_init(&min_v4_frag_size, IPF_V4_FRAG_SIZE_MIN_DEF);
+    atomic_init(&min_v6_frag_size, IPF_V6_FRAG_SIZE_MIN_DEF);
+    max_v4_frag_list_size = DIV_ROUND_UP(
+        IPV4_PACKET_MAX_SIZE - IPV4_PACKET_MAX_HDR_SIZE,
+        min_v4_frag_size - IPV4_PACKET_MAX_HDR_SIZE);
+    ipf_lock_unlock(&ipf_lock);
+    atomic_count_init(&nfrag, 0);
+    atomic_count_init(&n4frag_accepted, 0);
+    atomic_count_init(&n4frag_completed_sent, 0);
+    atomic_count_init(&n4frag_expired_sent, 0);
+    atomic_count_init(&n4frag_too_small, 0);
+    atomic_count_init(&n4frag_overlap, 0);
+    atomic_count_init(&n6frag_accepted, 0);
+    atomic_count_init(&n6frag_completed_sent, 0);
+    atomic_count_init(&n6frag_expired_sent, 0);
+    atomic_count_init(&n6frag_too_small, 0);
+    atomic_count_init(&n6frag_overlap, 0);
+    atomic_init(&nfrag_max, IPF_MAX_FRAGS_DEFAULT);
+    atomic_init(&ifp_v4_enabled, true);
+    atomic_init(&ifp_v6_enabled, true);
+}
+
+void
+ipf_destroy(void)
+{
+    ipf_lock_lock(&ipf_lock);
+
+    struct ipf_list *ipf_list;
+    HMAP_FOR_EACH_POP (ipf_list, node, &frag_lists) {
+        struct dp_packet *pkt;
+        while (ipf_list->last_sent_idx < ipf_list->last_inuse_idx) {
+            pkt = ipf_list->frag_list[ipf_list->last_sent_idx + 1].pkt;
+            dp_packet_delete(pkt);
+            atomic_count_dec(&nfrag);
+            ipf_list->last_sent_idx++;
+        }
+        free(ipf_list->frag_list);
+        free(ipf_list);
+    }
+
+    struct reassembled_pkt * rp;
+    LIST_FOR_EACH_POP (rp, rp_list_node, &reassembled_pkt_list) {
+        dp_packet_delete(rp->pkt);
+        free(rp);
+    }
+
+    hmap_destroy(&frag_lists);
+    ovs_list_poison(&frag_exp_list);
+    ovs_list_poison(&frag_complete_list);
+    ovs_list_poison(&reassembled_pkt_list);
+    ipf_lock_unlock(&ipf_lock);
+    ipf_lock_destroy(&ipf_lock);
+}
diff --git a/lib/ipf.h b/lib/ipf.h
new file mode 100644
index 0000000..5861e96
--- /dev/null
+++ b/lib/ipf.h
@@ -0,0 +1,63 @@ 
+/*
+ * Copyright (c) 2018 Nicira, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef IPF_H
+#define IPF_H 1
+
+#include "dp-packet.h"
+#include "openvswitch/types.h"
+
+struct ipf_status {
+   bool ifp_v4_enabled;
+   unsigned int min_v4_frag_size;
+   unsigned int nfrag_max;
+   unsigned int nfrag;
+   unsigned int n4frag_accepted;
+   unsigned int n4frag_completed_sent;
+   unsigned int n4frag_expired_sent;
+   unsigned int n4frag_too_small;
+   unsigned int n4frag_overlap;
+   bool ifp_v6_enabled;
+   unsigned int min_v6_frag_size;
+   unsigned int n6frag_accepted;
+   unsigned int n6frag_completed_sent;
+   unsigned int n6frag_expired_sent;
+   unsigned int n6frag_too_small;
+   unsigned int n6frag_overlap;
+};
+
+/* Collects and reassembles fragments which are to be sent through
+ * conntrack, if fragment processing is enabled or fragments are
+ * in flight. */
+void
+ipf_preprocess_conntrack(struct dp_packet_batch *pb, long long now,
+                         ovs_be16 dl_type, uint16_t zone, uint32_t hash_basis);
+
+/* Updates the state of fragments associated with reassembled packets and
+ * sends out fragments that are either associated with completed
+ * packets or expired, if fragment processing is enabled or fragments are
+ * in flight. */
+void
+ipf_postprocess_conntrack(struct dp_packet_batch *pb, long long now,
+                          ovs_be16 dl_type);
+
+void
+ipf_init(void);
+
+void
+ipf_destroy(void);
+
+#endif /* ipf.h */
diff --git a/tests/system-traffic.at b/tests/system-traffic.at
index 33a89c8..115bca9 100644
--- a/tests/system-traffic.at
+++ b/tests/system-traffic.at
@@ -1758,7 +1758,6 @@  AT_CLEANUP
 
 AT_SETUP([conntrack - IPv4 fragmentation])
 CHECK_CONNTRACK()
-CHECK_CONNTRACK_FRAG()
 OVS_TRAFFIC_VSWITCHD_START()
 
 ADD_NAMESPACES(at_ns0, at_ns1)
@@ -1792,7 +1791,6 @@  AT_CLEANUP
 
 AT_SETUP([conntrack - IPv4 fragmentation expiry])
 CHECK_CONNTRACK()
-CHECK_CONNTRACK_FRAG()
 OVS_TRAFFIC_VSWITCHD_START()
 
 ADD_NAMESPACES(at_ns0, at_ns1)
@@ -1823,7 +1821,6 @@  AT_CLEANUP
 
 AT_SETUP([conntrack - IPv4 fragmentation + vlan])
 CHECK_CONNTRACK()
-CHECK_CONNTRACK_FRAG()
 OVS_TRAFFIC_VSWITCHD_START()
 
 ADD_NAMESPACES(at_ns0, at_ns1)
@@ -1859,7 +1856,6 @@  AT_CLEANUP
 
 AT_SETUP([conntrack - IPv4 fragmentation + cvlan])
 CHECK_CONNTRACK()
-CHECK_CONNTRACK_FRAG()
 OVS_TRAFFIC_VSWITCHD_START([set Open_vSwitch . other_config:vlan-limit=0])
 OVS_CHECK_8021AD()
 
@@ -1912,7 +1908,6 @@  AT_CLEANUP
 
 AT_SETUP([conntrack - IPv6 fragmentation])
 CHECK_CONNTRACK()
-CHECK_CONNTRACK_FRAG()
 OVS_TRAFFIC_VSWITCHD_START()
 
 ADD_NAMESPACES(at_ns0, at_ns1)
@@ -1952,7 +1947,6 @@  AT_CLEANUP
 
 AT_SETUP([conntrack - IPv6 fragmentation expiry])
 CHECK_CONNTRACK()
-CHECK_CONNTRACK_FRAG()
 OVS_TRAFFIC_VSWITCHD_START()
 
 ADD_NAMESPACES(at_ns0, at_ns1)
@@ -1993,7 +1987,6 @@  AT_CLEANUP
 
 AT_SETUP([conntrack - IPv6 fragmentation + vlan])
 CHECK_CONNTRACK()
-CHECK_CONNTRACK_FRAG()
 OVS_TRAFFIC_VSWITCHD_START()
 
 ADD_NAMESPACES(at_ns0, at_ns1)
@@ -2036,7 +2029,6 @@  AT_CLEANUP
 
 AT_SETUP([conntrack - IPv6 fragmentation + cvlan])
 CHECK_CONNTRACK()
-CHECK_CONNTRACK_FRAG()
 OVS_TRAFFIC_VSWITCHD_START([set Open_vSwitch . other_config:vlan-limit=0])
 OVS_CHECK_8021AD()
 
@@ -2091,7 +2083,6 @@  AT_CLEANUP
 AT_SETUP([conntrack - Fragmentation over vxlan])
 OVS_CHECK_VXLAN()
 CHECK_CONNTRACK()
-CHECK_CONNTRACK_FRAG()
 CHECK_CONNTRACK_LOCAL_STACK()
 
 OVS_TRAFFIC_VSWITCHD_START()
@@ -2144,7 +2135,6 @@  AT_CLEANUP
 AT_SETUP([conntrack - IPv6 Fragmentation over vxlan])
 OVS_CHECK_VXLAN()
 CHECK_CONNTRACK()
-CHECK_CONNTRACK_FRAG()
 CHECK_CONNTRACK_LOCAL_STACK()
 
 OVS_TRAFFIC_VSWITCHD_START()