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From: Randi Botse <nightdecoder@gmail.com>
To: linux-c-programming@vger.kernel.org
Subject: UDP message boundary
Date: Mon, 15 Oct 2012 11:50:50 +0700	[thread overview]
Message-ID: <CAA6iF_7Hmu4c2FyGFRUw12QxK=t_tMvyu_xhMUjFGe7fCTxw5Q@mail.gmail.com> (raw)

Hi All

When using TCP socket, I loop send() or recv() until ALL the data has
been transmitted (or error, disconnect, etc.), because TCP socket
packet is transmitted in stream nature, maybe a byte, bytes or all
bytes in one transfer.

The UDP socket preserve message boundary which TCP socket doesn't.
Does this means single call to sendto() will processed by single call
recvfrom()?, and how about packet that exceeds UDP data MAX size?.

So in code, do I need to loop sendto() or recvfrom() to transmit the data?.

Example codes is:

char packet[100];
size_t nbytes = 0;
int ret;

while (nbytes < sizeof(packet)) {
    ret = recvfrom(socket, packet + nbytes, addr, 0,  sizeof(packet) - nbytes);
    if (ret <= 0) {
        /* deal with recvfrom() error */
    }
    nbytes += ret
}


Thanks

next             reply	other threads:[~2012-10-15  4:50 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-10-15  4:50 Randi Botse [this message]
2012-10-17  3:24 ` UDP message boundary Randi Botse
2012-10-19 14:15   ` Lorenzo Beretta
2012-10-19 15:03     ` Randi Botse
2012-10-20 21:55 ` Hendrik Visage
2012-10-21  9:46   ` Randi Botse

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