CODEWITHSUNDEEP
csocketstcp
Michal Pietras
Michal Pietras

Reputation: 442

Check how much data has been delivered to the destination using TCP/IP socket

I am developing a server application that needs to send a lot of data to the client. However, client can get disconnected at any time and send()/write() on socket will return an error in this case. I would like to check how much data has been actually delivered before a client get disconnected to be able to continue sending data from the place where it left off when the client reconnect.

Is it possible to check it using sockets API?

Upvotes: 3

Views: 296

Answers (1)

Celada
Celada

Reputation: 22261

No, the sockets API does not give you this information. In fact, it is not possible in general to know this. Depending on the particular way in which the connection failed, the TCP stack on one side generally can't know how much data successfully made it to the other side. The only thing it can know is how much data was acknowledged, which is not the same thing. And considering that other things than TCP/IP might have failed (the local OS, the remote OS, the remote process, the remote application logic), the amount of data that has been acknowledged at the TCP level probably doesn't mean much anyway.

You need to use an end-to-end application protocol to have the remote end acknowledge the data it has received and successfully processed (and committed, if applicable).

Upvotes: 6

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