Crash when namespace is longer than topic name

[afrixs]

ros-iron-image-transport-plugins version: 3.1.0-1jammy.20230908.194115

My node uses

image_transport::create_subscription(this, "input", [&](auto &msg) {}, "compressed", rmw_qos_profile_sensor_data);

When I run the node in a longer namespace, e.g. camera360, it crashes at this line

[sjgiewont]

I just ran into this same issue. As far as I'm aware the real issue is not due to the length of the namespace, but the namespace itself that is being referenced.

This section of code seems to be declaring the parameters for the image topics if they do not already exist. The problem is its trying to use the namespace of the subscriber node instead of the publisher node, which can be completely different! Ideally the namespace being referenced to determine ns_len (https://github.com/ros-perception/image_transport_plugins/blob/dd28c769bc22117ab32c15375b0c989bfb6d39a3/compressed_image_transport/src/compressed_subscriber.cpp#L79C10-L79C16) should be based on the namespace of base_topic, not the namespace of the current subscriber node. To my best knowledge this code was likely just copy pasted from the publisher source code, where using the node namespace is correct.

I was able to validate this quickly by changing my subscriber node namespace to match the namespace of the image topic being published. When i did this, the image transport was able to create the parameters correctly and there was no crash.

To ROS maintainers, what is the process for making this fix? Seems like this is an issue even in the latest rolling release.

[berndpfrommer]

I rediscovered this bug, but it's no longer in rolling and I don't see it in Jazzy either, just in Humble. This PR fixes the problem by fully resolving the topic before passing it to the plugins.

[berndpfrommer]

Apologies, it doesn't look like it's fixed in Jazzy.