tftpd: Use poll() instead of alarm() + setjmp().

[des]

Summary

While there, don't log an error when timing out waiting for a possible retransmit after a successful transfer.

Sponsored by: Klara, Inc.

[markj]

libexec/tftpd/tftp-io.c

380

Why not add a new parameter which lets the caller indicate what it wants?

401

Shouldn't we always log an error if poll() returns -1?

libexec/tftpd/tftp-transfer.c

439

I think a comment should explain why we don't want an error message here.

[des]

libexec/tftpd/tftp-io.c

380

I'm trying to change as little as possible.

401

It can't happen.

[markj]

libexec/tftpd/tftp-io.c

401

It can, if a bug elsewhere causes peer to be an invalid fd.

413

This check is always false.

[des]

libexec/tftpd/tftp-io.c

401

I'm confident that it can't happen. This isn't a library function that needs to take all possible contingencies into account.

413

Correct, the previous check should be removed as it's already been handled (even before my changes).

libexec/tftpd/tftp-transfer.c

439

Isn't it obvious? We expect to time out here, unless our final ACK was lost, causing the client to retransmit their final data packet.

[des]

Drop redundant timeout check.