On Sun, Jan 18, 2004 at 01:19:58PM -0800, Saint Aardvark the Carpeted wrote: > The problem seems to come in at lines 142/143: before this, > sin.sin_addr.s_addr is localhost (as set at line 130), as is > hent->h_addr_list[0][0]. *After* this, it's set with the Weird IP, > bind_tohost() is called, and packets go off to the Weird IP. > > ObDisclaimer: I Am Not A Programmer, and my knowledge of C is pretty > slim. But: if I change lines 142/143 to: > > bcopy(&hent->h_addr_list[0][0], &sin.sin_addr, sizeof sin.sin_addr); > > then the Weird IP doesn't show up in sin, and ypset only tries to bind > to the IP address listed in its arguments. > > Looking through man pages and header files, it looks like > hostent->h_addr_list is an array of pointers to chars (is that the > right term?): > > char **h_addr_list > > and so gethostbyname is returning the IP address as the *first entry* > in that list. It makes sense to me, then, that bcopy should have > h_addr_list[0][0] as its first argument.
Nice analysis. Yes, it looks to me like you've discovered a real bug here. Someone is taking the address of what is already a pointer -- an equivalent to the fix you show would be: bcopy(hent->h_addr_list[0], &sin.sin_addr, sizeof sin.sin_addr); which is possibly slightly clearer as to intent. Another point in your argument would be to convert those weird IP addresses to hexadecimal: 164.110.15.40 = 0xa46e0f28 132.110.15.40 = 0x846e0f28 and use gdb to compare those values with the contents of the *hent structure. Please do submit a PR with your analysis and a patch. It's slightly perturbing that no-one spotted this a long time ago, but these things happen from time to time. Cheers, Matthew -- Dr Matthew J Seaman MA, D.Phil. 26 The Paddocks Savill Way PGP: http://www.infracaninophile.co.uk/pgpkey Marlow Tel: +44 1628 476614 Bucks., SL7 1TH UK
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