Date: Wed, 1 Jul 1998 10:24:26 -0400 (EDT) From: Garrett Wollman <wollman@khavrinen.lcs.mit.edu> To: smoergrd@oslo.geco-prakla.slb.com (Dag-Erling Coidan Smørgrav) Cc: net@FreeBSD.ORG Subject: Length of incoming UDP datagrams Message-ID: <199807011424.KAA25111@khavrinen.lcs.mit.edu> In-Reply-To: <rx4yaud4vck.fsf@oslo.geco-prakla.slb.com> References: <rx4yaud4vck.fsf@oslo.geco-prakla.slb.com>
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<<On 01 Jul 1998 14:19:23 +0200, smoergrd@oslo.geco-prakla.slb.com (Dag-Erling Coidan Smørgrav) said:
> Is there any way to obtain information about the length of an incoming
> UDP datagram short of actually receiving it in a large enough
> buffer?
>From /sys/kern/sys_socket.c:
case FIONREAD:
*(int *)data = so->so_rcv.sb_cc;
return (0);
That will actually give you the total amount waiting in the buffer,
not just the first packet. Of course, UDP/IP also gives you a strict
upper bound of 65534-20-8 = 65506 bytes per packet.
-GAWollman
--
Garrett A. Wollman | O Siem / We are all family / O Siem / We're all the same
wollman@lcs.mit.edu | O Siem / The fires of freedom
Opinions not those of| Dance in the burning flame
MIT, LCS, CRS, or NSA| - Susan Aglukark and Chad Irschick
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