fragmentation-reassembly

code/bngblaster/src/bbl.c

@@ -527,6 +527,8 @@ main(int argc, char *argv[])
     if(igmp_group_count) g_ctx->config.igmp_group_count = atoi(igmp_group_count);
     if(igmp_zap_interval) g_ctx->config.igmp_zap_interval = atoi(igmp_zap_interval);
 
+    bbl_fragment_init();
+
 #ifdef BNGBLASTER_DPDK
     /* Init DPDK. */
     if(!io_dpdk_init()) {

code/bngblaster/src/bbl.h

@@ -50,6 +50,7 @@
 #include "bbl_tcp.h"
 #include "bbl_http_client.h"
 #include "bbl_http_server.h"
+#include "bbl_fragment.h"
 
 #include "io/io.h"
 #include "bgp/bgp.h"

code/bngblaster/src/bbl_access.c

@@ -631,11 +631,11 @@ bbl_access_rx_ipv4(bbl_access_interface_s *interface,
     bbl_udp_s *udp;
 
     if(ipv4->offset & ~IPV4_DF) {
-        /* Reassembling of fragmented IPv4 packets is currently not supported. */
         session->stats.accounting_packets_rx++;
         session->stats.accounting_bytes_rx += eth->length;
         session->stats.ipv4_fragmented_rx++;
         interface->stats.ipv4_fragmented_rx++;
+        bbl_fragment_rx(interface, NULL, eth, ipv4);
         return;
     }
 

code/bngblaster/src/bbl_config.c

@@ -3499,6 +3499,7 @@ json_parse_config(json_t *root)
             "stream-rate-calculation",
             "stream-delay-calculation",
             "stream-burst-ms",
+            "reassemble-fragments",
             "multicast-autostart",
             "udp-checksum"
         };
@@ -3531,6 +3532,10 @@ json_parse_config(json_t *root)
         if(value) {
             g_ctx->config.stream_burst_ms = json_number_value(value) * MSEC;
         }
+        JSON_OBJ_GET_BOOL(section, value, "traffic", "reassemble-fragments");
+        if(value) {
+            g_ctx->config.traffic_reassemble_fragments = json_boolean_value(value);
+        }
         JSON_OBJ_GET_BOOL(section, value, "traffic", "multicast-autostart");
         if(value) {
             g_ctx->config.multicast_traffic_autostart = json_boolean_value(value);

code/bngblaster/src/bbl_ctx.h

@@ -21,6 +21,7 @@ typedef struct bbl_ctx_
     struct timer_ *keyboard_timer;
 
     struct timer_ *tcp_timer;
+    struct timer_ *fragmentation_timer;
 
     struct timespec timestamp_start;
     struct timespec timestamp_stop;
@@ -93,6 +94,8 @@ typedef struct bbl_ctx_
     ldp_instance_s *ldp_instances;
     ldp_raw_update_s *ldp_raw_updates;
 
+    bbl_fragment_s *ipv4_fragments;
+
     /* Scratchpad memory */
     uint8_t *sp;
 
@@ -328,6 +331,7 @@ typedef struct bbl_ctx_
         /* Global Traffic */
         bool traffic_autostart;
         bool traffic_stop_verified;
+        bool traffic_reassemble_fragments;
 
         /* Stream Traffic */
         bool stream_autostart;

code/bngblaster/src/bbl_def.h

@@ -244,5 +244,6 @@ typedef struct bbl_http_client_ bbl_http_client_s;
 typedef struct bbl_http_server_config_ bbl_http_server_config_s;
 typedef struct bbl_http_server_ bbl_http_server_s;
 typedef struct bbl_http_server_connection_ bbl_http_server_connection_s;
+typedef struct bbl_fragment_ bbl_fragment_s;
 
 #endif

code/bngblaster/src/bbl_fragment.c

@@ -0,0 +1,188 @@
+/*
+ * BNG Blaster (BBL) - IP Fragmentation
+ *
+ * Christian Giese, October 2024
+ *
+ * Copyright (C) 2020-2024, RtBrick, Inc.
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+#include "bbl.h"
+
+static void
+bbl_fragment_free(bbl_fragment_s *ipv4_fragment)
+{
+    if(ipv4_fragment->next) {
+        ipv4_fragment->next->prev = ipv4_fragment->prev;
+    }
+    if(ipv4_fragment->prev) {
+        ipv4_fragment->prev->next = ipv4_fragment->next;
+    } else {
+        g_ctx->ipv4_fragments = ipv4_fragment->next;
+    }
+    free(ipv4_fragment);
+}
+
+/**
+ * bbl_fragment_rx
+ * 
+ * This function stores incoming IPv4 fragments in fragmentation buffers, 
+ * which are organized as a doubly-linked list. A cleanup job periodically 
+ * removes outdated buffers. Once all fragments of a single packet have been received, 
+ * the packet is reassembled and processed. 
+ * 
+ * Currently, this function supports BBL stream traffic only!
+ * 
+ * @param access_interface pointer to access interface on which packet was received
+ * @param network_interface pointer to network interface on which packet was received
+ * @param eth pointer to ethernet header structure of received packet
+ * @param ipv4 pointer to IPv4 header structure of received packet
+ */
+void 
+bbl_fragment_rx(bbl_access_interface_s *access_interface,
+                bbl_network_interface_s *network_interface,
+                bbl_ethernet_header_s *eth, bbl_ipv4_s *ipv4)
+{
+    if(!g_ctx->config.traffic_reassemble_fragments) return;
+
+    bbl_fragment_s *fragment = g_ctx->ipv4_fragments;
+    bbl_stream_s *stream;
+
+    uint8_t  *bbl_start;
+    bbl_bbl_s bbl;
+
+    uint16_t offset;
+
+    while(fragment) {
+        if(fragment->id == ipv4->id && 
+           fragment->src == ipv4->src && 
+           fragment->dst == ipv4->dst) {
+            break;
+        }
+        fragment = fragment->next;
+    }
+    if(!fragment) {
+        fragment = calloc(1, sizeof(bbl_fragment_s));
+        fragment->id = ipv4->id;
+        fragment->src = ipv4->src;
+        fragment->dst = ipv4->dst;
+        if(g_ctx->ipv4_fragments) {
+            g_ctx->ipv4_fragments->prev = fragment;
+            fragment->next = g_ctx->ipv4_fragments;
+        }
+        g_ctx->ipv4_fragments = fragment;
+    }
+
+    offset = (ipv4->offset & 0x1FFF) * 8;
+    if(offset+ipv4->payload_len > sizeof(fragment->buf)) {
+        LOG(INFO, "IPv4 fragmented packet to big (%u)\n", (offset+ipv4->payload_len));
+        bbl_fragment_free(fragment);
+        return;
+    }
+
+    if(eth->length > fragment->max_length) {
+        fragment->max_length = eth->length;
+    }
+    if(offset > fragment->max_offset) {
+        fragment->max_offset = offset;
+    }
+
+    fragment->fragments++;
+    fragment->timestamp = eth->timestamp.tv_sec;
+
+    memcpy(fragment->buf+offset, ipv4->payload, ipv4->payload_len);
+    fragment->recived += ipv4->payload_len;
+
+    if(!(ipv4->offset & IPV4_MF)) {
+        /* Last fragment recieved. */
+        fragment->expected = offset + ipv4->payload_len;
+    }
+    if(fragment->recived == fragment->expected) {
+        /* All fragments received. */
+        if(packet_is_bbl(fragment->buf, fragment->recived)) {
+            /* Currently, we support only the reassembly of BBL stream packets. */
+            bbl_start = fragment->buf + (fragment->recived-BBL_HEADER_LEN);
+            bbl.type = *(bbl_start+8);
+            bbl.sub_type = *(bbl_start+9);
+            bbl.direction = *(bbl_start+10);
+            bbl.tos = *(bbl_start+11);
+            bbl.session_id = *(uint32_t*)(bbl_start+12);
+            if(bbl.type == BBL_TYPE_UNICAST) {
+                bbl.ifindex = *(uint32_t*)(bbl_start+16);
+                bbl.outer_vlan_id = *(uint16_t*)(bbl_start+20);
+                bbl.inner_vlan_id = *(uint16_t*)(bbl_start+22);
+                bbl.mc_source = 0;
+                bbl.mc_source = 0;
+            } else {
+                bbl.mc_source = *(uint32_t*)(bbl_start+16);
+                bbl.mc_source = *(uint32_t*)(bbl_start+20);
+                bbl.ifindex = 0;
+                bbl.outer_vlan_id = 0;
+                bbl.inner_vlan_id = 0;
+            }
+            bbl.flow_id = *(uint64_t*)(bbl_start+24);
+            bbl.flow_seq = *(uint64_t*)(bbl_start+32);
+            bbl.timestamp.tv_sec = *(uint32_t*)(bbl_start+40);
+            bbl.timestamp.tv_nsec = *(uint32_t*)(bbl_start+44);
+
+            eth->bbl = &bbl;
+            eth->length = fragment->max_length;
+
+            if(access_interface) {
+                stream = bbl_stream_rx(eth, NULL);
+                if(stream) {
+                    if(stream->rx_access_interface == NULL) {
+                        stream->rx_access_interface = access_interface;
+                    }
+                }
+            } else if (network_interface) {
+                stream = bbl_stream_rx(eth, network_interface->mac);
+                if(stream) {
+                    if(stream->rx_network_interface != network_interface) {
+                        if(stream->rx_network_interface) {
+                            /* RX interface has changed! */
+                            stream->rx_interface_changes++;
+                            stream->rx_interface_changed_epoch = eth->timestamp.tv_sec;
+                        }
+                        stream->rx_network_interface = network_interface;
+                    }
+                }
+            }
+            if(stream) {
+                if(fragment->fragments > stream->rx_fragments) {
+                    stream->rx_fragments = fragment->fragments;
+                }
+                if(fragment->max_offset > stream->rx_fragment_offset) {
+                    stream->rx_fragment_offset = fragment->max_offset;
+                }
+            }
+        }
+        bbl_fragment_free(fragment);
+    }
+}
+
+void
+bbl_fragment_cleanup_job(timer_s *timer)
+{
+    bbl_fragment_s *fragment = g_ctx->ipv4_fragments;
+    bbl_fragment_s *next = fragment;
+
+    /* Delete all fragments older than 10 seconds. */
+    uint32_t timestamp = timer->timestamp->tv_sec - 10;
+    while(next) {
+        fragment = next;
+        next = fragment->next;
+        if(fragment->timestamp < timestamp) {
+            bbl_fragment_free(fragment);
+        } 
+    }
+}
+
+void
+bbl_fragment_init()
+{
+    if(!g_ctx->config.traffic_reassemble_fragments) return;
+
+    timer_add_periodic(&g_ctx->timer_root, &g_ctx->fragmentation_timer, 
+                       "FRAGMENT", 3, 0, NULL,
+                       &bbl_fragment_cleanup_job);
+}

code/bngblaster/src/bbl_fragment.h

@@ -0,0 +1,39 @@
+/*
+ * BNG Blaster (BBL) - IP Fragmentation
+ *
+ * Christian Giese, October 2024
+ *
+ * Copyright (C) 2020-2024, RtBrick, Inc.
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef __BBL_FRAGMENT_H__
+#define __BBL_FRAGMENT_H__
+
+typedef struct bbl_fragment_ {
+    uint32_t    timestamp;
+    uint32_t    src;
+    uint32_t    dst;
+    uint16_t    id;
+    uint16_t    fragments; /* Number of fragments */
+    uint16_t    max_offset; /* Max offset value */
+    uint16_t    max_length; /* Max length (L2) */
+    uint16_t    recived;
+    uint16_t    expected;
+
+    struct bbl_fragment_ *prev;
+    struct bbl_fragment_ *next;
+
+    uint8_t     buf[4050];
+
+} bbl_fragment_s;
+
+void 
+bbl_fragment_rx(bbl_access_interface_s *access_interface,
+                bbl_network_interface_s *network_interface,
+                bbl_ethernet_header_s *eth, bbl_ipv4_s *ipv4);
+
+void
+bbl_fragment_init();
+
+#endif

code/bngblaster/src/bbl_network.c

@@ -469,6 +469,8 @@ bbl_network_rx_handler(bbl_network_interface_s *interface,
             } else if(ipv4->protocol == PROTOCOL_IPV4_OSPF && interface->ospfv2_interface) {
                 ospf_handler_rx_ipv4(interface, eth, ipv4);
                 return;
+            } else if(ipv4->offset & ~IPV4_DF) {
+                bbl_fragment_rx(NULL, interface, eth, ipv4);
             }
             break;
         case ETH_TYPE_IPV6:

code/bngblaster/src/bbl_stream.c

@@ -2173,6 +2173,9 @@ bbl_stream_reset(bbl_stream_s *stream)
     stream->rx_min_delay_us = 0;
     stream->rx_max_delay_us = 0;
     stream->rx_len = 0;
+    stream->rx_fragments = 0;
+    stream->rx_fragment_offset = 0;
+    stream->rx_ttl = 0;
     stream->rx_priority = 0;
     stream->rx_outer_vlan_pbit = 0;
     stream->rx_inner_vlan_pbit = 0;
@@ -2596,6 +2599,10 @@ bbl_stream_json(bbl_stream_s *stream, bool debug)
             json_object_set_new(root, "rx-interface-changes", json_integer(stream->rx_interface_changes));
             json_object_set_new(root, "rx-interface-changed-epoch", json_integer(stream->rx_interface_changed_epoch));
         }
+        if(stream->rx_fragments) {
+            json_object_set_new(root, "rx-fragments", json_integer(stream->rx_fragments));
+            json_object_set_new(root, "rx-fragment-offset", json_integer(stream->rx_fragment_offset));
+        }
         if(stream->config->rx_mpls1) { 
             json_object_set_new(root, "rx-mpls1-expected", json_integer(stream->config->rx_mpls1_label));
         }

code/bngblaster/src/bbl_stream.h

@@ -197,6 +197,9 @@ typedef struct bbl_stream_
     __time_t rx_interface_changed_epoch;
     uint8_t  rx_interface_changes;
 
+    uint8_t  rx_fragments;
+    uint16_t rx_fragment_offset; /* Max fragmentation offset received */
+
     uint8_t  rx_ttl; /* IPv4 or IPv6 TTL */
     uint8_t  rx_priority; /* IPv4 TOS or IPv6 TC */
     uint8_t  rx_outer_vlan_pbit;

docs/_sources/configuration/traffic.rst.txt

@@ -52,4 +52,9 @@
 +---------------------------------+--------------------------------------------------------+
 | **udp-checksum**                | | Enable UDP checksums.                                |
 |                                 | | Default: false                                       |
++---------------------------------+--------------------------------------------------------+
+| **reassemble-fragments**        | | Enable reassembly of fragmented IPv4 stream packets. |
+|                                 | | Currently, this is restricted to BBL stream traffic  |
+|                                 | | only!                                                |
+|                                 | | Default: false                                       |
 +---------------------------------+--------------------------------------------------------+