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Fixed RT 938 having to do with SIOCGIFCONF on Linux. We now do a first

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pass in which we pass a null pointer for the buffer, and we will get
back the length of the buffer we should allocate. This is because
if you pass in a buffer that is too small, Linux (unlike other OSes)
will not tell you that it is too small by returning a length greater
than the length you passed in.
This commit is contained in:
Ben Cottrell 2001-03-17 02:11:29 +00:00
parent ed5ee59141
commit c73ced691d
2 changed files with 32 additions and 1 deletions
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32
common/discover.c
View File

@ -43,7 +43,7 @@
#ifndef lint
static char copyright[] =
"$Id: discover.c,v 1.38 2001/02/17 21:16:44 mellon Exp $ Copyright (c) 1995-2000 The Internet Software Consortium. All rights reserved.\n";
"$Id: discover.c,v 1.39 2001/03/17 02:11:27 tamino Exp $ Copyright (c) 1995-2000 The Internet Software Consortium. All rights reserved.\n";
#endif /* not lint */
#include "dhcpd.h"
@ -157,8 +157,38 @@ void discover_interfaces (state)
log_fatal ("Can't create addrlist socket");
/* Get the interface configuration information... */
#ifdef SIOCGIFCONF_NULL_BUF_GIVES_CORRECT_LEN
/* linux will only tell us how long a buffer it wants if we give it
* a null buffer first. So, do a dry run to figure out the length.
*
* XXX this code is duplicated from below because trying to fold
* the logic into the if statement and goto resulted in excesssive
* obfuscation. The intent is that unless you run Linux you shouldn't
* have to deal with this. */
ic.ifc_len = 0;
ic.ifc_ifcu.ifcu_buf = (caddr_t)NULL;
i = ioctl(sock, SIOCGIFCONF, &ic);
if (i < 0)
log_fatal ("ioctl: SIOCGIFCONF: %m");
ic.ifc_ifcu.ifcu_buf = dmalloc ((size_t)ic.ifc_len, MDL);
if (!ic.ifc_ifcu.ifcu_buf)
log_fatal ("Can't allocate SIOCGIFCONF buffer.");
#else /* SIOCGIFCONF_NULL_BUF_GIVES_CORRECT_LEN */
/* otherwise, we just feed it a starting size, and it'll tell us if
* it needs more */
ic.ifc_len = sizeof buf;
ic.ifc_ifcu.ifcu_buf = (caddr_t)buf;
#endif /* SIOCGIFCONF_NULL_BUF_GIVES_CORRECT_LEN */
gifconf_again:
i = ioctl(sock, SIOCGIFCONF, &ic);

1
includes/cf/linux.h
View File

@ -151,6 +151,7 @@ extern int h_errno;
#define ALIAS_NAMES_PERMUTED
#define SKIP_DUMMY_INTERFACES
#define SIOCGIFCONF_NULL_BUF_GIVES_CORRECT_LEN
#ifdef NEED_PRAND_CONF
#ifndef HAVE_DEV_RANDOM