[ros-users] getting a topic's md5sum without subscribing

[Ken Tossell]

Hey ROS,

I'm working on a node to send messages between other nodes (the proxy
subscribes to a topic, the publisher sends one copy of a message to it,
then it forwards the message to several nodes). I need to find the MD5 sum
of all of the topics so that the proxy can advertise its version of /topic
as /proxy/topic using the correct signature.

I had planned to get the MD5 sum using master::getTopics(), but where
TopicInfo is supposed to have [name, type, md5], getTopics()'s output is
[name, type, type]. (The underlying RPC doesn't convey the MD5 sum,
either.)

Is there any way to determine the MD5 sum of a topic without first
subscribing to it?

Thanks,
Ken