wsrep_sst_xtrabackup-v2 still doesn't support IPv6

I'm upgrading our XtraDB Cluster install from 5.6.30 to 5.6.34, and I wanted to point out that the newly-rewritten wsrep_sst_xtrabackup-v2 *still* does not support IPv6.

Specific issues:

   * Address parsing (in `setup_ports()`) still doesn't handle IPv6 address literals with colons in them.
   * `socat` creates IPv4-only sockets (using `TCP-LISTEN:`) instead of dual-stack sockets (using `TCP6-LISTEN:` on most modern linuxes)

I have our puppet install patching this file, but it's incredibly annoying to have to port our patches to every new release. It would be great if this tool could support IPv6 natively.

The current patch I'm using is below:

--- wsrep_sst_xtrabackup-v2 2016-12-13 08:53:55.000000000 +0000
+++ /proc/self/fd/11 2016-12-27 21:19:50.991911578 +0000
@@ -385,11 +385,11 @@
             if [[ $encrypt -eq 1 ]]; then
                 wsrep_log_warning "**** WARNING **** encrypt=1 is deprecated and will be removed in a future release"
             fi

             if [[ "$WSREP_SST_OPT_ROLE" == "joiner" ]]; then
- tcmd="socat -u TCP-LISTEN:${TSST_PORT},reuseaddr${sockopt} stdio"
+ tcmd="socat -u TCP6-LISTEN:${TSST_PORT},reuseaddr${sockopt} stdio"
             else
                 tcmd="socat -u stdio TCP:${REMOTEIP}:${TSST_PORT}${sockopt}"
             fi
         fi
     fi
@@ -634,16 +634,19 @@
 }

 setup_ports()
 {
     if [[ "$WSREP_SST_OPT_ROLE" == "donor" ]];then
- SST_PORT=$(echo $WSREP_SST_OPT_ADDR | awk -F '[:/]' '{ print $2 }')
- REMOTEIP=$(echo $WSREP_SST_OPT_ADDR | awk -F ':' '{ print $1 }')
- lsn=$(echo $WSREP_SST_OPT_ADDR | awk -F '[:/]' '{ print $4 }')
- sst_ver=$(echo $WSREP_SST_OPT_ADDR | awk -F '[:/]' '{ print $5 }')
+ SST_PORT=$(echo ${WSREP_SST_OPT_ADDR##*:} | tr -d [])
+ REMOTEIP="$(echo ${WSREP_SST_OPT_ADDR%:*} | tr -d [])"
+ if [[ "$REMOTEIP" =~ : ]] ; then
+ REMOTEIP="[$REMOTEIP]"
+ fi
+ lsn=$(echo $WSREP_SST_OPT_ADDR | awk -F '[/]' '{ print $3 }' | tr -d [])
+ sst_ver=$(echo $WSREP_SST_OPT_ADDR | awk -F '[/]' '{ print $4 }' | tr -d [])
     else
- SST_PORT=$(echo ${WSREP_SST_OPT_ADDR} | awk -F ':' '{ print $2 }')
+ SST_PORT=$(echo ${WSREP_SST_OPT_ADDR##*:} | tr -d [])
     fi
 }

 # waits ~10 seconds for nc to open the port and then reports ready
 # (regardless of timeout)