On 01.05.19 21:47, Brandon Noel wrote:
Hi, We are using lwIP’s (STABLE-2.1.2) non-blocking BSD socket interface in an application. Our current setup is two threads which each have their own socket and are communicating with different peers. Currently if lwip_send() returns -1 we call getsockopt(SOL_SOCKET, SO_ERROR) to get the error for that socket. We are unsure about what types of errors lwIP supports with getsockopt() and how to appropriately handle those errors. What is the appropriate way to handle getsockopt(SOL_SOCKET, SO_ERROR) returning a fatal error? Should we call lwip_close()? Is it improper to call lwip_close() (in other words we should do nothing because of possible double freeing)? Does it depend on the error type? We also cannot rely on errno because of race conditions between the two threads.
Calling close is required if you're sure that the socket was valid as it's not closed internally otherwise. The lwIP pcb *is* freed by the stack, but not the socket. In contrast, there's no check that the socket is yours, so if you just call close() with any integer in the socket range, you could close some connection. There's no risk of double-free though. About 'errno': it's more or less mandatory for this to be a per-thread value, so you might want to implement thread-local storage. Implementing nonblocking socket programs without errno is rather pointless I guess... Regards, Simon _______________________________________________ lwip-users mailing list lwip-users@nongnu.org https://lists.nongnu.org/mailman/listinfo/lwip-users
