Manage `ip mptcp endpoint` state on linux

manage_mptcp_endpoint.sh

#!/bin/bash
set -e

echo "[+] Clearling old mptcp endpoints"
for i in `ip mptcp endpoint show|cut -d " " -f 3`; do
    ip mptcp endpoint delete id $i;
done

declare -A OLD

ID=1

(echo YES; ip monitor address) | while read LINE; do
    echo "[.] Update"

    declare -A NEW
    while read -r IFACE ADDR; do
        L="$ADDR dev $IFACE"
        if [ "${OLD[$L]}" == "" ] && [ "${NEW[$L]}" == "" ]; then
            NEW["$L"]="$ID"
            echo "ip mptcp endpoint add $L id $ID subflow"
            ip mptcp endpoint add $L id $ID subflow
            ID=$[$ID+1]
        elif [ "${NEW[$L]}" != "" ]; then
            NEW["$L"]="${OLD["$L"]}"
            unset OLD["$L"]
            # already there
        fi
    done <<< $(\
               ip -j address \
                   | jq -r \
                        ".[] \
                        | select( .operstate | contains(\"UP\") ) \
                        | .ifname as \$ifname \
                        | .addr_info[] \
                        | select(.scope | contains(\"global\")) \
                        | select(.temporary | . == null or . == \"\") \
                        | \$ifname + \" \" + .local" \
         )


    for OLDL in "${!OLD[@]}"; do
        DID="${OLD["$OLDL"]}"
        echo "ip mptcp endpoint delete id $DID # $OLDL"
        ip mptcp endpoint delete id $DID
        unset OLD["$OLDL"]
        unset NEW["$OLDL"]
    done

    for L in "${!NEW[@]}"; do
        OLD["$L"]="${NEW["$L"]}"
    done
done

Nice script!

Note that you can replace the first for loop to remove the old MPTCP endpoints by:

ip mptcp endpoint flush