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some clarification on if_getmtu()

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- avoid to use freed (by freeifaddrs) data
  - 1st try getifaddrs, then try SIOCGIFMTU as the last resort

Submitted by:	JINMEI Tatuya <jinmei@isl.rdc.toshiba.co.jp>
Obtained from:	KAME Project
This commit is contained in:
Hajimu UMEMOTO 2000-10-28 17:57:38 +00:00
parent 7363d0e795
commit 7c991abcbc
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=67801
1 changed files with 35 additions and 25 deletions
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60
usr.sbin/rtadvd/if.c
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@ -1,4 +1,4 @@
/* $KAME: if.c,v 1.9 2000/05/27 11:30:43 jinmei Exp $ */
/* $KAME: if.c,v 1.14 2000/10/25 04:28:34 jinmei Exp $ */
/*
* Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
@ -148,42 +148,44 @@ if_nametosdl(char *name)
int
if_getmtu(char *name)
{
#if 0
struct ifreq ifr;
int s;
if ((s = socket(AF_INET6, SOCK_DGRAM, 0)) < 0)
return(0);
ifr.ifr_addr.sa_family = AF_INET6;
strncpy(ifr.ifr_name, name, sizeof(ifr.ifr_name));
if (ioctl(s, SIOCGIFMTU, (caddr_t)&ifr) < 0) {
close(s);
return(0);
}
close(s);
return(ifr.ifr_mtu);
#else
struct ifaddrs *ifap, *ifa;
struct if_data *ifd;
u_long mtu = 0;
if (getifaddrs(&ifap) < 0)
return(0);
for (ifa = ifap; ifa; ifa = ifa->ifa_next) {
if (strcmp(ifa->ifa_name, name) == 0) {
ifd = ifa->ifa_data;
freeifaddrs(ifap);
if (ifd)
return ifd->ifi_mtu;
else
return 0;
mtu = ifd->ifi_mtu;
break;
}
}
freeifaddrs(ifap);
return 0;
#ifdef SIOCGIFMTU /* XXX: this ifdef may not be necessary */
if (mtu == 0) {
struct ifreq ifr;
int s;
if ((s = socket(AF_INET6, SOCK_DGRAM, 0)) < 0)
return(0);
ifr.ifr_addr.sa_family = AF_INET6;
strncpy(ifr.ifr_name, name,
sizeof(ifr.ifr_name));
if (ioctl(s, SIOCGIFMTU, (caddr_t)&ifr) < 0) {
close(s);
return(0);
}
close(s);
mtu = ifr.ifr_mtu;
}
#endif
return(mtu);
}
/* give interface index and its old flags, then new flags returned */
@ -206,6 +208,7 @@ if_getflags(int ifindex, int oifflags)
close(s);
return (oifflags & ~IFF_UP);
}
close(s);
return (ifr.ifr_flags);
}
@ -410,7 +413,6 @@ get_prefixlen(char *buf)
{
struct rt_msghdr *rtm = (struct rt_msghdr *)buf;
struct sockaddr *sa, *rti_info[RTAX_MAX];
int masklen;
u_char *p, *lim;
sa = (struct sockaddr *)(rtm + 1);
@ -419,6 +421,14 @@ get_prefixlen(char *buf)
p = (u_char *)(&SIN6(sa)->sin6_addr);
lim = (u_char *)sa + sa->sa_len;
return prefixlen(p, lim);
}
int
prefixlen(u_char *p, u_char *lim)
{
int masklen;
for (masklen = 0; p < lim; p++) {
switch (*p) {
case 0xff: