Easier netlink captures

easycap.sh

#!/usr/bin/env bash

set -euo pipefail

clean_up_strace_io() {
  printf -- 'command: %s\n' "${*}"
  printf -- 'messages:\n'
  declare line
  declare strace_parse
  declare label
  declare message=""
  while read -r line; do
    if [[ "${line}" =~ "sendto"* ]] || [[ "${line}" =~ "recvmsg"* ]] || [[ "${line}" =~ "sendmsg"* ]]; then
      if [[ -n "${message}" ]]; then
        printf -- '      message: "%s"\n' "${message}"
      fi
      message=""
      strace_parse="${line}"
      label="$(
        sed 's|sendto(\([0-9]\+\).*|sendto \1|;s|sendmsg(\([0-9]\+\).*|sendmsg \1|;s|recvmsg(\([0-9]\+\).*|recvmsg \1|;' <<< "${strace_parse}"
      )"
      printf -- '    - op: %s\n' "${label}"
      printf -- '      strace-parse: %s\n' "${strace_parse}"
      continue
    fi
    # remove stray message size lines
    if [[ "${line}" =~ "bytes in buffer" ]]; then
      continue
    fi
    message+="$(cut -d' ' -f3-21  <<< "${line}" | sed 's| \+||g')"
  done
  if [[ -n "${message}" ]]; then
    printf -- '      message: "%s"\n' "${message}"
  fi
}

trace_send_recv() {
  strace \
    -e sendto,sendmsg,recvmsg \
    --quiet=all \
    --string-limit=999999999 \
    --write=3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20 \
    --read=3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20 \
    --strings-in-hex=all \
    --const-print-style=raw \
    --output=>(clean_up_strace_io "${@}" > /tmp/trace.yml) \
    "${@}"
}

trace_send_recv ip route
wait
cat /tmp/trace.yml