In order to find the target, it seems that all we need to do is simply break the pathname apart at the / characters and see if each component exists in the dirblocks member of the extended attributes structure. While that's basically true at the highest level, as the saying goes, "The devil is in the details."
Permission-checks complicate this matter slightly. Symbolic links complicate this matter significantly (a symbolic link can point to a file, a directory, or another symbolic link). And, to make things even more complicated, under certain conditions the target may not even exist, so we may need to operate on the directory entry above the target instead of the target itself.
So, the connect function (c_open()) calls connect_msg_to_attr(), which in turn calls pathwalk().