如何从挖掘结果解析 SRV 记录的端口？

Question

我正在像这样解析dig的输出，以获取SRV记录的端口。

export SERVER_DNS_NAME=myserver
echo "SERVER_DNS_NAME: " $SERVER_DNS_NAME
echo "dig: " $(dig +noall +answer $SERVER_DNS_NAME SRV )
echo "port old: " $(dig +noall +answer $SERVER_DNS_NAME SRV | cut -d ' ' -f 6)
SERVER_DIG_RESULT=$(dig +noall +answer $SERVER_DNS_NAME SRV )
echo "SERVER_DIG_RESULT: " $SERVER_DIG_RESULT
SERVER_STRING_ARRAY=($SERVER_DIG_RESULT)
for i in "${SERVER_STRING_ARRAY[@]}"
do
  :
  echo $i
done
SERVER_PORT=${SERVER_STRING_ARRAY[6]}
echo "server port new: " $SERVER_PORT
if [ -z $SERVER_PORT ]; then
  echo "invalid port"
  exit 1
fi
until nc -z $SERVER_DNS_NAME $SERVER_PORT
... do something

我的问题是，有时端口位于数组项6，有时位于7。

我的问题是：如何从挖掘结果可靠地解析端口

Answer 1

将+short选项用于dig，这将为您提供最简短的输出，然后对其进行简单的解析：

% dig +short _xmpp-client._tcp.jabber.org. SRV
31 30 5222 hermes2v6.jabber.org.
30 30 5222 hermes2.jabber.org.

Answer 2

你可能也喜欢这个：

host -t SRV mySRVdomain.local                                           
# mySRVdomain.local has SRV record 1 1 2368 e04dc24b-96c6-4b52-8356-42be0d34e7bb.mySRVdomain.local.

# get it as host:port
host -t SRV mySRVdomain.local | sed -r 's/.+ ([^ ]+) ([^ ]+).$/2:1/g'
# This will print: e04dc24b-96c6-4b52-8356-42be0d34e7bb.mySRVdomain.local:2368
# which is the first real URL with PORT

它可能与您需要的不完全相同，但您可以获得

Answer 3

使用Curl和AWK形成一个快速命令：

curl http://$(dig +short {HOST} srv | awk '{printf "%s:%sn",$4,$3}')