How to get caller pid in zmq (local socket)

Question

Im new to zmq. Im using the same for local IPC in a Linux based OS (The socket is AF_UNIX type) But I could not find a way to get the caller's (client) process Id. Is there any way to find the same using zmq ? (Finding the pid of the caller is must for my access control requirement and if zmq does not provide the same then I should switch to dbus) Please help me.

Answer 1

Forget most of the low-level socket designs and worries. Think higher in the sky. ZeroMQ is a pretty higher-level messaging concept. So you will have zero-worries about most of the socket-io problems.

For more on these ZMQ principles, read Pieter Hintjens' design maxims and his resources-rich book "Code Connected, Vol.1".

That said, the solution is fully in your control.

Solution

Create a problem-specific multi-zmq-socket / multi-zmq-pattern (multiple zmq-primitives used and orchestrated by your application level logic) as a problem-specific formal communication handshaking.

Ensure the <sender> adds it's own PID into message.

Re/authorise via another register/auth-socket-pattern with the pre-registered sender from the receiver side, so as to avoid a spoofed attack under a fake/stolen PID-identity.

Adapt your access-control policy according to your ProblemDOMAIN, use and implement any level of crypto-security formal handshaking protocols for identity-validation or key-exchange, to raise your access-control policy security to adequate strengths ( including MIL-STD grades ).