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内核路由表：fib_table
路由表项的增加和查询，fib_table_insert和fib_table_lookup。
跟踪fib_table_insert和fib_table_lookup两个接口。
#!/usr/bin/env bpftrace #include <linux/pci.h> #include <linux/netdevice.h> kprobe:fib_table_insert { printf("fib_table_insert\n"); @[kstack]=count(); } kprobe:fib_table_lookup { printf("fib_table_lookup\n"); @[kstack]=count(); }在创建路由的时候，可以捕获到fib_table_insert接口的使用。
正常的接受报文会触发路由表的查询。
1）一个是接收报文路径，会有入向input路由表的查找；
2）一个是用户态发起connec/bind，或者内核tcp接受路径回复ack的时候，会有出向output路由表的创建和查找。
[root@localhost leiyanjie]# bpftrace route.bt Attaching 2 probes... fib_table_lookup fib_table_lookup fib_table_lookup fib_table_lookup fib_table_lookup fib_table_lookup fib_table_lookup fib_table_lookup fib_table_lookup fib_table_lookup fib_table_lookup fib_table_lookup fib_table_lookup fib_table_lookup fib_table_lookup fib_table_lookup fib_table_lookup fib_table_lookup fib_table_lookup fib_table_lookup fib_table_lookup fib_table_lookup fib_table_lookup fib_table_lookup fib_table_lookup fib_table_lookup fib_table_lookup fib_table_lookup fib_table_lookup fib_table_lookup fib_table_lookup fib_table_lookup fib_table_lookup fib_table_lookup fib_table_lookup fib_table_lookup fib_table_lookup fib_table_lookup fib_table_lookup fib_table_lookup ^C @[ fib_table_lookup+1 ip_route_output_key_hash_rcu+942 ip_route_output_key_hash+90 ip_route_output_flow+25 inet_csk_route_req+221 tcp_conn_request+898 tcp_rcv_state_process+382 tcp_v4_do_rcv+186 tcp_v4_rcv+3577 ip_protocol_deliver_rcu+48 ip_local_deliver_finish+68 ip_local_deliver+255 ip_rcv+216 __netif_receive_skb_one_core+137 process_backlog+158 net_rx_action+309 __do_softirq+188 asm_call_sysvec_on_stack+15 do_softirq_own_stack+55 do_softirq.part.18+47 __local_bh_enable_ip+79 ip_finish_output2+384 ip_output+109 __ip_queue_xmit+359 __tcp_transmit_skb+2638 tcp_connect+2856 tcp_v4_connect+1237 __inet_stream_connect+210 inet_stream_connect+54 __sys_connect+154 __x64_sys_connect+22 do_syscall_64+48 entry_SYSCALL_64_after_hwframe+98 ]: 1 @[ fib_table_lookup+1 __inet_dev_addr_type.isra.28+167 __inet6_bind+675 __sys_bind+211 __x64_sys_bind+22 do_syscall_64+48 entry_SYSCALL_64_after_hwframe+98 ]: 1 @[ fib_table_lookup+1 ip_route_output_key_hash_rcu+942 ip_route_output_key_hash+90 ip_route_output_flow+25 inet_csk_route_child_sock+286 tcp_v4_syn_recv_sock+912 tcp_v6_syn_recv_sock+1568 tcp_check_req+306 tcp_v4_rcv+2456 ip_protocol_deliver_rcu+48 ip_local_deliver_finish+68 ip_local_deliver+255 ip_rcv+216 __netif_receive_skb_one_core+137 process_backlog+158 net_rx_action+309 __do_softirq+188 asm_call_sysvec_on_stack+15 do_softirq_own_stack+55 do_softirq.part.18+47 __local_bh_enable_ip+79 ip_finish_output2+384 ip_output+109 __ip_queue_xmit+359 __tcp_transmit_skb+2638 tcp_rcv_synsent_state_process+1803 tcp_rcv_state_process+235 tcp_v4_do_rcv+186 __release_sock+121 release_sock+43 inet_stream_connect+65 __sys_connect+154 __x64_sys_connect+22 do_syscall_64+48 entry_SYSCALL_64_after_hwframe+98 ]: 1 @[ fib_table_lookup+1 ip_route_output_key_hash_rcu+942 ip_route_output_key_hash+90 ip_route_output_flow+25 ip_send_unicast_reply+480 tcp_v4_send_ack+648 tcp_v4_rcv+1259 ip_protocol_deliver_rcu+48 ip_local_deliver_finish+68 ip_local_deliver+255 ip_rcv+216 __netif_receive_skb_one_core+137 process_backlog+158 net_rx_action+309 __do_softirq+188 asm_call_sysvec_on_stack+15 do_softirq_own_stack+55 do_softirq.part.18+47 flush_smp_call_function_from_idle+68 do_idle+328 cpu_startup_entry+25 start_secondary+276 secondary_startup_64_no_verify+176 ]: 3 @[ fib_table_lookup+1 ip_route_output_key_hash_rcu+942 ip_route_output_key_hash+90 ip_route_output_flow+25 tcp_v4_connect+1209 __inet_stream_connect+210 inet_stream_connect+54 __sys_connect+154 __x64_sys_connect+22 do_syscall_64+48 entry_SYSCALL_64_after_hwframe+98 ]: 4 @[ fib_table_lookup+1 ip_route_output_key_hash_rcu+942 ip_route_output_key_hash+90 ip_route_output_flow+25 tcp_v4_connect+357 __inet_stream_connect+210 inet_stream_connect+54 __sys_connect+154 __x64_sys_connect+22 do_syscall_64+48 entry_SYSCALL_64_after_hwframe+98 ]: 4 @[ fib_table_lookup+1 ip_route_output_key_hash_rcu+942 ip_route_output_key_hash+90 tcp_v4_connect+943 __inet_stream_connect+210 inet_stream_connect+54 __sys_connect+154 __x64_sys_connect+22 do_syscall_64+48 entry_SYSCALL_64_after_hwframe+98 ]: 4 @[ fib_table_lookup+1 ip_route_input_slow+492 ip_route_input_rcu+609 ip_route_input_noref+37 ip_rcv_finish_core.isra.22+101 ip_rcv_finish+100 ip_rcv+216 __netif_receive_skb_one_core+137 process_backlog+158 net_rx_action+309 __do_softirq+188 asm_call_sysvec_on_stack+15 do_softirq_own_stack+55 do_softirq.part.18+47 flush_smp_call_function_from_idle+68 do_idle+328 cpu_startup_entry+25 start_secondary+276 secondary_startup_64_no_verify+176 ]: 11 @[ fib_table_lookup+1 __fib_validate_source+326 fib_validate_source+70 ip_route_input_slow+2498 ip_route_input_rcu+609 ip_route_input_noref+37 ip_rcv_finish_core.isra.22+101 ip_rcv_finish+100 ip_rcv+216 __netif_receive_skb_one_core+137 process_backlog+158 net_rx_action+309 __do_softirq+188 asm_call_sysvec_on_stack+15 do_softirq_own_stack+55 do_softirq.part.18+47 flush_smp_call_function_from_idle+68 do_idle+328 cpu_startup_entry+25 start_secondary+276 secondary_startup_64_no_verify+176 ]: 11