Date: Thu, 5 Jun 2008 17:12:47 +0200 From: Marc =?iso-8859-1?q?L=F6rner?= <marc.loerner@hob.de> To: freebsd-net@freebsd.org Subject: Probable Bug in tcp.h Message-ID: <200806051712.47048.marc.loerner@hob.de>
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Hello,
I probably found a bug in declaration of "struct tcphdr"!
struct tcphdr {
u_short th_sport; /* source port */
u_short th_dport; /* destination port */
tcp_seq th_seq; /* sequence number */
tcp_seq th_ack; /* acknowledgement number */
#if BYTE_ORDER == LITTLE_ENDIAN
u_int th_x2:4, /* (unused) */ <---here
th_off:4; /* data offset */ <---
#endif
#if BYTE_ORDER == BIG_ENDIAN
u_int th_off:4, /* data offset */
th_x2:4; /* (unused) */
#endif
u_char th_flags;
First of all I have the problam of misalignment of th_off. Because in this way
always 4 bytes are read and the the bits of th_off are replaced. Then the 4
bytes are written back.
But should (th_x and th_off) not only be 1 byte in whole -> only read and
write 1 byte?
I think if this was changed, my misalignment problems would go away!
I'll appreciate any thoughts on this!
Regards,
Marc
P.S.: Please cc me because I'm not on the list!
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