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BSD: Use MSG_DONTROUTE for unicast packets on FreeBSD

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BSD systems cannot use SO_DONTROUTE, because it does not work properly
with multicast packets (perhaps it tries to find iface based on multicast
group address). But we can use MSG_DONTROUTE sendmsg() flag for unicast
packets. Works on FreeBSD, is ignored on OpenBSD and is broken on NetBSD
(i guess due to integrated routing table and ARP table).
This commit is contained in:
Ondrej Zajicek (work) 2018-07-28 16:54:06 +02:00
parent 0ed3129f6b
commit 318acb0f6c
4 changed files with 16 additions and 1 deletions
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3
lib/ip.h
View file

@ -241,6 +241,9 @@ static inline int ip6_is_v4mapped(ip6_addr a)
#define ipa_classify(x) ip6_classify(&(x))
#define ipa_is_link_local(x) ip6_is_link_local(x)
static inline int ip4_is_unicast(ip4_addr a)
{ return _I(a) < 0xe0000000; }
/* XXXX remove */
static inline int ipa_classify_net(ip_addr a)
{ return ipa_zero2(a) ? (IADDR_HOST | SCOPE_UNIVERSE) : ipa_classify(a); }

5
sysdep/bsd/sysio.h
View file

@ -12,6 +12,11 @@
#include <sys/param.h>
#ifdef __FreeBSD__
/* Should be defined in sysdep/cf/bsd.h, but it is flavor-specific */
#define CONFIG_DONTROUTE_UNICAST
#endif
#ifdef __NetBSD__
#ifndef IP_RECVTTL

1
sysdep/cf/README
View file

@ -11,6 +11,7 @@ CONFIG_MC_PROPER_SRC Multicast packets have source address according to socket s
CONFIG_SKIP_MC_BIND Don't call bind on multicast socket (def for *BSD)
CONFIG_NO_IFACE_BIND Bind to iface is not available, use workarounds (def for *BSD)
CONFIG_UNIX_DONTROUTE Use setsockopts DONTROUTE (undef for *BSD)
CONFIG_DONTROUTE_UNICAST Use MSG_DONTROUTE flag for unicast packets (def for FreeBSD)
CONFIG_USE_HDRINCL Use IP_HDRINCL instead of control messages for source address on raw IP sockets.
CONFIG_RESTRICTED_PRIVILEGES Implements restricted privileges using drop_uid()

8
sysdep/unix/io.c
View file

@ -1541,6 +1541,7 @@ sk_sendmsg(sock *s)
struct iovec iov = {s->tbuf, s->tpos - s->tbuf};
byte cmsg_buf[CMSG_TX_SPACE];
sockaddr dst;
int flags = 0;
sockaddr_fill(&dst, s->af, s->daddr, s->iface, s->dport);
@ -1551,6 +1552,11 @@ sk_sendmsg(sock *s)
.msg_iovlen = 1
};
#ifdef CONFIG_DONTROUTE_UNICAST
if (ipa_is_ip4(s->daddr) && ip4_is_unicast(ipa_to_ip4(s->daddr)))
flags = MSG_DONTROUTE;
#endif
#ifdef CONFIG_USE_HDRINCL
byte hdr[20];
struct iovec iov2[2] = { {hdr, 20}, iov };
@ -1566,7 +1572,7 @@ sk_sendmsg(sock *s)
if (s->flags & SKF_PKTINFO)
sk_prepare_cmsgs(s, &msg, cmsg_buf, sizeof(cmsg_buf));
return sendmsg(s->fd, &msg, 0);
return sendmsg(s->fd, &msg, flags);
}
static inline int