CODEWITHSUNDEEP
c++linuxsocketstcpbuffer
user1639653
user1639653

Reputation:

What happens on buffer overflow?

I read somewhere that every TCP connection has it's own 125kB output and input buffer. What happens if this buffer is full, and I still continue sending data on linux?

According to http://www.kernel.org/doc/man-pages/online/pages/man2/send.2.html the packets are just silently dropped, without notifying me. What can I do to stop this from happening? Is there any way to find out if at least some of my data has been sent correctly, so that I can continue at a later point in time?

Upvotes: 2

Views: 2150

Answers (2)

selbie
selbie

Reputation: 104494

Short answer is this. "send" calls on a TCP socket will just block until the TCP sliding window (or internal queue buffers) opens up as a result of the remote endpoint receiving and consuming data. It's not much different than trying to write bytes to a file faster than the disk can save it.

If your socket is configured for non-blocking mode, send will return EWOULDBLOCK or EAGAIN, until data can be sent. Standard poll, select, and epoll calls will work as expected so you know when to "send" again.

Upvotes: 7

Jon Trauntvein
Jon Trauntvein

Reputation: 4554

I don't know that the "packets are dropped". I think that what is more likely is that the calls that the program makes to write() will either block or return a failure.

Upvotes: 0

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