tracing: log_p2p_connections.bt example

A bpftrace script that logs information from the
net:*_connection tracepoints.

I've tested this script with bpftrace version 0.14.1 and v0.20.2.

Author: 0xB10C

contrib/tracing/README.md

@@ -335,4 +335,25 @@ $ python3 contrib/tracing/mempool_monitor.py $(pidof bitcoind)
  │ 13:10:32Z added c78e87be86c828137a6e7e00a177c03b52202ce4c39029b99904c2a094b9da87 with feerate 11.00 sat/vB (1562 sat, 142 vbytes)                                            │
  │                                                                                                                                                                              │
  └──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘
+
+### log_p2p_connections.bt
+
+A `bpftrace` script to log information about opened, closed, misbehaving, and
+evicted P2P connections. Uses the `net:*_connection` tracepoints.
+
+```bash
+$ bpftrace contrib/tracing/log_p2p_connections.bt
+```
+
+This should produce an output similar to the following.
+
+```bash
+Attaching 6 probes...
+Logging opened, closed, misbehaving, and evicted P2P connections
+OUTBOUND conn to 127.0.0.1:15287: id=0, type=block-relay-only, network=0, total_out=1
+INBOUND conn from 127.0.0.1:45324: id=1, type=inbound, network=0, total_in=1
+MISBEHAVING conn id=1, score_before=0, score_increase=20, message='getdata message size = 50001', threshold_exceeded=false
+CLOSED conn to 127.0.0.1:15287: id=0, type=block-relay-only, network=0, established=1231006505
+EVICTED conn to 127.0.0.1:45324: id=1, type=inbound, network=0, established=1612312312
+...
 ```

contrib/tracing/log_p2p_connections.bt

@@ -0,0 +1,51 @@
+#!/usr/bin/env bpftrace
+
+BEGIN
+{
+  printf("Logging opened, closed, misbehaving, and evicted P2P connections\n")
+}
+
+usdt:./build/src/bitcoind:net:inbound_connection
+{
+  $id = (int64) arg0;
+  $addr = str(arg1);
+  $conn_type = str(arg2);
+  $network = (int32) arg3;
+  $existing = (uint64) arg4;
+  printf("INBOUND conn from %s: id=%ld, type=%s, network=%d, total=%d\n", $addr, $id, $conn_type, $network, $existing);
+}
+
+usdt:./build/src/bitcoind:net:outbound_connection
+{
+  $id = (int64) arg0;
+  $addr = str(arg1);
+  $conn_type = str(arg2);
+  $network = (int32) arg3;
+  $existing = (uint64) arg4;
+  printf("OUTBOUND conn to %s: id=%ld, type=%s, network=%d, total=%d\n", $addr, $id, $conn_type, $network, $existing);
+}
+
+usdt:./build/src/bitcoind:net:closed_connection
+{
+  $id = (int64) arg0;
+  $addr = str(arg1);
+  $conn_type = str(arg2);
+  $network = (int32) arg3;
+  printf("CLOSED conn to %s: id=%ld, type=%s, network=%d, established=%ld\n", $addr, $id, $conn_type, $network, arg4);
+}
+
+usdt:./build/src/bitcoind:net:evicted_inbound_connection
+{
+  $id = (int64) arg0;
+  $addr = str(arg1);
+  $conn_type = str(arg2);
+  $network = (int32) arg3;
+  printf("EVICTED conn to %s: id=%ld, type=%s, network=%d, established=%ld\n", $addr, $id, $conn_type, $network, arg4);
+}
+
+usdt:./build/src/bitcoind:net:misbehaving_connection
+{
+  $id = (int64) arg0;
+  $message = str(arg1);
+  printf("MISBEHAVING conn id=%ld, message='%s'\n", $id, $message);
+}