baids-find-optimal-peers

#!/bin/bash
# apt install -y netcat-traditional mtr jq curl

function find-optimal-peers-get-relay-hops() {

  # This will stop counting hops on 5th imcp-unreachable hop
  # or on finished, successful traceroute
  mtr --json -c 1 -n -Z 1 -G 1 -U 5 ${1} | jq -r .report.hubs[].count | sort -n | tail -n1 | awk '{print $1}'

}

function find-optimal-peers-get-relay-avg-latency() {

  # Let's assume we're going to get as bad latency as the average of the
  # slowest of 3 probes from the hub
  mtr --json -c 3 -n -Z 1 -G 1 -U 5 ${1} | jq -r .report.hubs[].Avg | sort -n | tail -n1

}

function find-optimal-peers-by-hops() {

  find-optimal-peers hops

}

function find-optimal-peers-by-avg-latency() {

  find-optimal-peers avg-latency

}

function find-optimal-peers-check-depends() {

  # TODO:
  # apt install -y netcat-traditional mtr jq curl
  true

}

function find-optimal-peers-init() {

  MAX_PEERS=10
  PROBE_CONN_TIMEOUT=1
  SOURCE_ROUTE_POINTER=4
  TOPOLOGY_JSON_URL=https://explorer.mainnet.cardano.org/relays/topology.json
  TOPOLOGY_JSON_FILE=/tmp/topology.json
  PROXIMITY_TOPOLOGY_JSON=/tmp/proximity-topology.json

}

function find-optimal-peers() {

  find-optimal-peers-init

  export METRIC=${1:-avg-latency}
  
  curl -sLo ${TOPOLOGY_JSON_FILE} ${TOPOLOGY_JSON_URL}
  
  echo '{"Producers":[]}' > ${TOPOLOGY_JSON_FILE}.tmp
  
  jq -r '.Producers[] | "\(.addr):\(.port)"' ${TOPOLOGY_JSON_FILE} | while read line
  do
    ADDR=$(echo ${line} | awk -F: '{print $1}')
    PORT=$(echo ${line} | awk -F: '{print $2}')
    nc -G ${SOURCE_ROUTE_POINTER} -w ${PROBE_CONN_TIMEOUT} -zv ${ADDR} ${PORT} &> /dev/null
    # if connected, extract valency from the peers file
    if [ $? -eq 0 ]
    then
      VALENCY=$(jq -r \
                   --arg addr ${ADDR} \
                   --arg port ${PORT} \
                   '.Producers[] | select((.addr==($addr | tostring)) and (.port==($port | tonumber))) | .valency' 2> /dev/null \
                   ${TOPOLOGY_JSON_FILE})
      if [[ "${VALENCY}" == "null" ]] || [[ "${VALENCY}" == "" ]]
      then
        VALENCY=1
      fi
      jq -r \
         --arg addr ${ADDR} \
         --arg port ${PORT} \
         --arg valency ${VALENCY} \
         '.Producers += [{"addr":$addr,"port":($port|tonumber),"valency":($valency|tonumber)}]' \
         ${TOPOLOGY_JSON_FILE}.tmp > ${TOPOLOGY_JSON_FILE}
      mv ${TOPOLOGY_JSON_FILE} ${TOPOLOGY_JSON_FILE}.tmp
    fi
  done
  cp -a ${TOPOLOGY_JSON_FILE}.tmp ${TOPOLOGY_JSON_FILE}
  
  jq -r .Producers[].addr ${TOPOLOGY_JSON_FILE} | sort | uniq | \
    while read relay
    do
      VALUE=$(find-optimal-peers-get-relay-${METRIC} ${relay})
      echo "${VALUE} - ${relay}"
    done | sort -n -k1 > /tmp/find-optimal-peers-${METRIC}.log
  
  echo '{"Producers":[]}' > ${PROXIMITY_TOPOLOGY_JSON}.tmp
  head -n ${MAX_PEERS} /tmp/find-optimal-peers-${METRIC}.log | awk '{print $3}' | while read peer
  do
    PEER_OBJECTS=$(jq -r \
                     --arg addr ${peer} \
                     '.Producers[] | select(.addr==($addr | tostring))' \
                     ${TOPOLOGY_JSON_FILE} | \
                     jq -r --slurp . | \
                     awk '{printf "%s",$0} END {print ""}')
    jq -r \
       --argjson peer "${PEER_OBJECTS}" \
       '.Producers += $peer' \
       ${PROXIMITY_TOPOLOGY_JSON}.tmp > ${PROXIMITY_TOPOLOGY_JSON}
    mv ${PROXIMITY_TOPOLOGY_JSON} ${PROXIMITY_TOPOLOGY_JSON}.tmp
  done
  jq -r . ${PROXIMITY_TOPOLOGY_JSON}.tmp > ${PROXIMITY_TOPOLOGY_JSON}
  
}