svn commit: r264905 - in head: sys/net sys/netinet sys/netinet6 tests/sys/netinet
Alan Somers
asomers at FreeBSD.org
Thu Apr 24 23:56:59 UTC 2014
Author: asomers
Date: Thu Apr 24 23:56:56 2014
New Revision: 264905
URL: http://svnweb.freebsd.org/changeset/base/264905
Log:
Fix subnet and default routes on different FIBs on the same subnet.
These two bugs are closely related. The root cause is that ifa_ifwithnet
does not consider FIBs when searching for an interface address.
sys/net/if_var.h
sys/net/if.c
Add a fib argument to ifa_ifwithnet and ifa_ifwithdstadddr. Those
functions will only return an address whose interface fib equals the
argument.
sys/net/route.c
Update calls to ifa_ifwithnet and ifa_ifwithdstaddr with fib
arguments.
sys/netinet/in.c
Update in_addprefix to consider the interface fib when adding
prefixes. This will prevent it from not adding a subnet route when
one already exists on a different fib.
sys/net/rtsock.c
sys/netinet/in_pcb.c
sys/netinet/ip_output.c
sys/netinet/ip_options.c
sys/netinet6/nd6.c
Add RT_DEFAULT_FIB arguments to ifa_ifwithdstaddr and ifa_ifwithnet.
In some cases it there wasn't a clear specific fib number to use.
In others, I was unable to test those functions so I chose
RT_DEFAULT_FIB to minimize divergence from current behavior. I will
fix some of the latter changes along with PR kern/187553.
tests/sys/netinet/fibs_test.sh
tests/sys/netinet/udp_dontroute.c
tests/sys/netinet/Makefile
Revert r263738. The udp_dontroute test was right all along.
However, bugs kern/187550 and kern/187553 cancelled each other out
when it came to this test. Because of kern/187553, ifa_ifwithnet
searched the default fib instead of the requested one, but because
of kern/187550, there was an applicable subnet route on the default
fib. The new test added in r263738 doesn't work right, however. I
can verify with dtrace that ifa_ifwithnet returned the wrong address
before I applied this commit, but route(8) miraculously found the
correct interface to use anyway. I don't know how.
Clear expected failure messages for kern/187550 and kern/187552.
PR: kern/187550
PR: kern/187552
Reviewed by: melifaro
MFC after: 3 weeks
Sponsored by: Spectra Logic
Added:
head/tests/sys/netinet/udp_dontroute.c
- copied unchanged from r263737, head/tests/sys/netinet/udp_dontroute.c
Modified:
head/sys/net/if.c
head/sys/net/if_var.h
head/sys/net/route.c
head/sys/net/rtsock.c
head/sys/netinet/in.c
head/sys/netinet/in_pcb.c
head/sys/netinet/ip_options.c
head/sys/netinet/ip_output.c
head/sys/netinet6/nd6.c
head/tests/sys/netinet/Makefile
head/tests/sys/netinet/fibs_test.sh
Modified: head/sys/net/if.c
==============================================================================
--- head/sys/net/if.c Thu Apr 24 23:28:09 2014 (r264904)
+++ head/sys/net/if.c Thu Apr 24 23:56:56 2014 (r264905)
@@ -1653,7 +1653,7 @@ done:
*/
/*ARGSUSED*/
struct ifaddr *
-ifa_ifwithdstaddr(struct sockaddr *addr)
+ifa_ifwithdstaddr(struct sockaddr *addr, int fibnum)
{
struct ifnet *ifp;
struct ifaddr *ifa;
@@ -1662,6 +1662,8 @@ ifa_ifwithdstaddr(struct sockaddr *addr)
TAILQ_FOREACH(ifp, &V_ifnet, if_link) {
if ((ifp->if_flags & IFF_POINTOPOINT) == 0)
continue;
+ if ((ifp->if_fib != fibnum))
+ continue;
IF_ADDR_RLOCK(ifp);
TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
if (ifa->ifa_addr->sa_family != addr->sa_family)
@@ -1686,7 +1688,7 @@ done:
* is most specific found.
*/
struct ifaddr *
-ifa_ifwithnet(struct sockaddr *addr, int ignore_ptp)
+ifa_ifwithnet(struct sockaddr *addr, int ignore_ptp, int fibnum)
{
struct ifnet *ifp;
struct ifaddr *ifa;
@@ -1706,12 +1708,14 @@ ifa_ifwithnet(struct sockaddr *addr, int
/*
* Scan though each interface, looking for ones that have addresses
- * in this address family. Maintain a reference on ifa_maybe once
- * we find one, as we release the IF_ADDR_RLOCK() that kept it stable
- * when we move onto the next interface.
+ * in this address family and the requested fib. Maintain a reference
+ * on ifa_maybe once we find one, as we release the IF_ADDR_RLOCK() that
+ * kept it stable when we move onto the next interface.
*/
IFNET_RLOCK_NOSLEEP();
TAILQ_FOREACH(ifp, &V_ifnet, if_link) {
+ if (ifp->if_fib != fibnum)
+ continue;
IF_ADDR_RLOCK(ifp);
TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
char *cp, *cp2, *cp3;
Modified: head/sys/net/if_var.h
==============================================================================
--- head/sys/net/if_var.h Thu Apr 24 23:28:09 2014 (r264904)
+++ head/sys/net/if_var.h Thu Apr 24 23:56:56 2014 (r264905)
@@ -495,8 +495,8 @@ int ifa_switch_loopback_route(struct ifa
struct ifaddr *ifa_ifwithaddr(struct sockaddr *);
int ifa_ifwithaddr_check(struct sockaddr *);
struct ifaddr *ifa_ifwithbroadaddr(struct sockaddr *);
-struct ifaddr *ifa_ifwithdstaddr(struct sockaddr *);
-struct ifaddr *ifa_ifwithnet(struct sockaddr *, int);
+struct ifaddr *ifa_ifwithdstaddr(struct sockaddr *, int);
+struct ifaddr *ifa_ifwithnet(struct sockaddr *, int, int);
struct ifaddr *ifa_ifwithroute(int, struct sockaddr *, struct sockaddr *);
struct ifaddr *ifa_ifwithroute_fib(int, struct sockaddr *, struct sockaddr *, u_int);
struct ifaddr *ifaof_ifpforaddr(struct sockaddr *, struct ifnet *);
Modified: head/sys/net/route.c
==============================================================================
--- head/sys/net/route.c Thu Apr 24 23:28:09 2014 (r264904)
+++ head/sys/net/route.c Thu Apr 24 23:56:56 2014 (r264905)
@@ -582,7 +582,7 @@ rtredirect_fib(struct sockaddr *dst,
}
/* verify the gateway is directly reachable */
- if ((ifa = ifa_ifwithnet(gateway, 0)) == NULL) {
+ if ((ifa = ifa_ifwithnet(gateway, 0, fibnum)) == NULL) {
error = ENETUNREACH;
goto out;
}
@@ -739,7 +739,7 @@ ifa_ifwithroute_fib(int flags, struct so
*/
ifa = NULL;
if (flags & RTF_HOST)
- ifa = ifa_ifwithdstaddr(dst);
+ ifa = ifa_ifwithdstaddr(dst, fibnum);
if (ifa == NULL)
ifa = ifa_ifwithaddr(gateway);
} else {
@@ -748,10 +748,10 @@ ifa_ifwithroute_fib(int flags, struct so
* or host, the gateway may still be on the
* other end of a pt to pt link.
*/
- ifa = ifa_ifwithdstaddr(gateway);
+ ifa = ifa_ifwithdstaddr(gateway, fibnum);
}
if (ifa == NULL)
- ifa = ifa_ifwithnet(gateway, 0);
+ ifa = ifa_ifwithnet(gateway, 0, fibnum);
if (ifa == NULL) {
struct rtentry *rt = rtalloc1_fib(gateway, 0, RTF_RNH_LOCKED, fibnum);
if (rt == NULL)
@@ -865,7 +865,7 @@ rt_getifa_fib(struct rt_addrinfo *info,
*/
if (info->rti_ifp == NULL && ifpaddr != NULL &&
ifpaddr->sa_family == AF_LINK &&
- (ifa = ifa_ifwithnet(ifpaddr, 0)) != NULL) {
+ (ifa = ifa_ifwithnet(ifpaddr, 0, fibnum)) != NULL) {
info->rti_ifp = ifa->ifa_ifp;
ifa_free(ifa);
}
Modified: head/sys/net/rtsock.c
==============================================================================
--- head/sys/net/rtsock.c Thu Apr 24 23:28:09 2014 (r264904)
+++ head/sys/net/rtsock.c Thu Apr 24 23:56:56 2014 (r264905)
@@ -735,7 +735,8 @@ route_output(struct mbuf *m, struct sock
rt->rt_ifp->if_type == IFT_PROPVIRTUAL) {
struct ifaddr *ifa;
- ifa = ifa_ifwithnet(info.rti_info[RTAX_DST], 1);
+ ifa = ifa_ifwithnet(info.rti_info[RTAX_DST], 1,
+ RT_DEFAULT_FIB);
if (ifa != NULL)
rt_maskedcopy(ifa->ifa_addr,
&laddr,
Modified: head/sys/netinet/in.c
==============================================================================
--- head/sys/netinet/in.c Thu Apr 24 23:28:09 2014 (r264904)
+++ head/sys/netinet/in.c Thu Apr 24 23:56:56 2014 (r264905)
@@ -617,7 +617,7 @@ in_addprefix(struct in_ifaddr *target, i
{
struct in_ifaddr *ia;
struct in_addr prefix, mask, p, m;
- int error, fibnum;
+ int error;
if ((flags & RTF_HOST) != 0) {
prefix = target->ia_dstaddr.sin_addr;
@@ -628,9 +628,8 @@ in_addprefix(struct in_ifaddr *target, i
prefix.s_addr &= mask.s_addr;
}
- fibnum = rt_add_addr_allfibs ? RT_ALL_FIBS : target->ia_ifp->if_fib;
-
IN_IFADDR_RLOCK();
+ /* Look for an existing address with the same prefix, mask, and fib */
TAILQ_FOREACH(ia, &V_in_ifaddrhead, ia_link) {
if (rtinitflags(ia)) {
p = ia->ia_dstaddr.sin_addr;
@@ -646,6 +645,8 @@ in_addprefix(struct in_ifaddr *target, i
mask.s_addr != m.s_addr)
continue;
}
+ if (target->ia_ifp->if_fib != ia->ia_ifp->if_fib)
+ continue;
/*
* If we got a matching prefix route inserted by other
@@ -664,6 +665,10 @@ in_addprefix(struct in_ifaddr *target, i
IN_IFADDR_RUNLOCK();
return (EEXIST);
} else {
+ int fibnum;
+
+ fibnum = rt_add_addr_allfibs ? RT_ALL_FIBS :
+ target->ia_ifp->if_fib;
rt_addrmsg(RTM_ADD, &target->ia_ifa, fibnum);
IN_IFADDR_RUNLOCK();
return (0);
Modified: head/sys/netinet/in_pcb.c
==============================================================================
--- head/sys/netinet/in_pcb.c Thu Apr 24 23:28:09 2014 (r264904)
+++ head/sys/netinet/in_pcb.c Thu Apr 24 23:56:56 2014 (r264905)
@@ -745,9 +745,11 @@ in_pcbladdr(struct inpcb *inp, struct in
struct in_ifaddr *ia;
struct ifnet *ifp;
- ia = ifatoia(ifa_ifwithdstaddr((struct sockaddr *)sin));
+ ia = ifatoia(ifa_ifwithdstaddr((struct sockaddr *)sin,
+ RT_DEFAULT_FIB));
if (ia == NULL)
- ia = ifatoia(ifa_ifwithnet((struct sockaddr *)sin, 0));
+ ia = ifatoia(ifa_ifwithnet((struct sockaddr *)sin, 0,
+ RT_DEFAULT_FIB));
if (ia == NULL) {
error = ENETUNREACH;
goto done;
@@ -862,9 +864,10 @@ in_pcbladdr(struct inpcb *inp, struct in
sain.sin_len = sizeof(struct sockaddr_in);
sain.sin_addr.s_addr = faddr->s_addr;
- ia = ifatoia(ifa_ifwithdstaddr(sintosa(&sain)));
+ ia = ifatoia(ifa_ifwithdstaddr(sintosa(&sain), RT_DEFAULT_FIB));
if (ia == NULL)
- ia = ifatoia(ifa_ifwithnet(sintosa(&sain), 0));
+ ia = ifatoia(ifa_ifwithnet(sintosa(&sain), 0,
+ RT_DEFAULT_FIB));
if (ia == NULL)
ia = ifatoia(ifa_ifwithaddr(sintosa(&sain)));
Modified: head/sys/netinet/ip_options.c
==============================================================================
--- head/sys/netinet/ip_options.c Thu Apr 24 23:28:09 2014 (r264904)
+++ head/sys/netinet/ip_options.c Thu Apr 24 23:56:56 2014 (r264905)
@@ -227,8 +227,11 @@ dropit:
if (opt == IPOPT_SSRR) {
#define INA struct in_ifaddr *
#define SA struct sockaddr *
- if ((ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr)) == NULL)
- ia = (INA)ifa_ifwithnet((SA)&ipaddr, 0);
+ if ((ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr,
+ RT_DEFAULT_FIB)) == NULL) {
+ ia = (INA)ifa_ifwithnet((SA)&ipaddr, 0,
+ RT_DEFAULT_FIB);
+ }
} else
/* XXX MRT 0 for routing */
ia = ip_rtaddr(ipaddr.sin_addr, M_GETFIB(m));
Modified: head/sys/netinet/ip_output.c
==============================================================================
--- head/sys/netinet/ip_output.c Thu Apr 24 23:28:09 2014 (r264904)
+++ head/sys/netinet/ip_output.c Thu Apr 24 23:56:56 2014 (r264905)
@@ -230,7 +230,8 @@ again:
*/
if (flags & IP_SENDONES) {
if ((ia = ifatoia(ifa_ifwithbroadaddr(sintosa(dst)))) == NULL &&
- (ia = ifatoia(ifa_ifwithdstaddr(sintosa(dst)))) == NULL) {
+ (ia = ifatoia(ifa_ifwithdstaddr(sintosa(dst),
+ RT_DEFAULT_FIB))) == NULL) {
IPSTAT_INC(ips_noroute);
error = ENETUNREACH;
goto bad;
@@ -241,8 +242,10 @@ again:
ip->ip_ttl = 1;
isbroadcast = 1;
} else if (flags & IP_ROUTETOIF) {
- if ((ia = ifatoia(ifa_ifwithdstaddr(sintosa(dst)))) == NULL &&
- (ia = ifatoia(ifa_ifwithnet(sintosa(dst), 0))) == NULL) {
+ if ((ia = ifatoia(ifa_ifwithdstaddr(sintosa(dst),
+ RT_DEFAULT_FIB))) == NULL &&
+ (ia = ifatoia(ifa_ifwithnet(sintosa(dst), 0,
+ RT_DEFAULT_FIB))) == NULL) {
IPSTAT_INC(ips_noroute);
error = ENETUNREACH;
goto bad;
Modified: head/sys/netinet6/nd6.c
==============================================================================
--- head/sys/netinet6/nd6.c Thu Apr 24 23:28:09 2014 (r264904)
+++ head/sys/netinet6/nd6.c Thu Apr 24 23:56:56 2014 (r264905)
@@ -945,7 +945,7 @@ nd6_is_new_addr_neighbor(struct sockaddr
* If the address is assigned on the node of the other side of
* a p2p interface, the address should be a neighbor.
*/
- dstaddr = ifa_ifwithdstaddr((struct sockaddr *)addr);
+ dstaddr = ifa_ifwithdstaddr((struct sockaddr *)addr, RT_DEFAULT_FIB);
if (dstaddr != NULL) {
if (dstaddr->ifa_ifp == ifp) {
ifa_free(dstaddr);
Modified: head/tests/sys/netinet/Makefile
==============================================================================
--- head/tests/sys/netinet/Makefile Thu Apr 24 23:28:09 2014 (r264904)
+++ head/tests/sys/netinet/Makefile Thu Apr 24 23:56:56 2014 (r264905)
@@ -1,7 +1,12 @@
# $FreeBSD$
TESTSDIR= ${TESTSBASE}/sys/netinet
+BINDIR= ${TESTSDIR}
ATF_TESTS_SH+= fibs_test
+PROG= udp_dontroute
+SRCS= udp_dontroute.c
+NO_MAN=
+WARNS?= 6
.include <bsd.test.mk>
Modified: head/tests/sys/netinet/fibs_test.sh
==============================================================================
--- head/tests/sys/netinet/fibs_test.sh Thu Apr 24 23:28:09 2014 (r264904)
+++ head/tests/sys/netinet/fibs_test.sh Thu Apr 24 23:56:56 2014 (r264905)
@@ -175,7 +175,6 @@ default_route_with_multiple_fibs_on_same
default_route_with_multiple_fibs_on_same_subnet_body()
{
- atf_expect_fail "kern/187552 default route uses the wrong interface when multiple interfaces have the same subnet but different fibs"
# Configure the TAP interfaces to use a RFC5737 nonrouteable addresses
# and a non-default fib
ADDR0="192.0.2.2"
@@ -225,7 +224,6 @@ subnet_route_with_multiple_fibs_on_same_
subnet_route_with_multiple_fibs_on_same_subnet_body()
{
- atf_expect_fail "kern/187550 Multiple interfaces on different FIBs but the same subnet don't all have a subnet route"
# Configure the TAP interfaces to use a RFC5737 nonrouteable addresses
# and a non-default fib
ADDR0="192.0.2.2"
@@ -253,66 +251,54 @@ subnet_route_with_multiple_fibs_on_same_
cleanup_tap
}
-# Regression test for kern/187553 "Source address selection for UDP packets
-# with SO_DONTROUTE uses the default FIB". The original complaint was that a
-# UDP packet with SO_DONTROUTE set would select a source address from an
-# interface on the default FIB instead of the process FIB.
+# Test that source address selection works correctly for UDP packets with
+# SO_DONTROUTE set that are sent on non-default FIBs.
# This bug was discovered with "setfib 1 netperf -t UDP_STREAM -H some_host"
# Regression test for kern/187553
-
+#
# The root cause was that ifa_ifwithnet() did not have a fib argument. It
# would return an address from an interface on any FIB that had a subnet route
# for the destination. If more than one were available, it would choose the
-# most specific. The root cause is most easily tested by creating two
-# interfaces with overlapping subnet routes, adding a default route to the
-# interface with the less specific subnet route, and looking up a host that
-# requires the default route using the FIB of the interface with the less
-# specific subnet route. "route get" should provide a route that uses the
-# interface on the chosen FIB. However, absent the patch for this bug it will
-# instead use the other interface.
-atf_test_case src_addr_selection_by_subnet cleanup
-src_addr_selection_by_subnet_head()
+# most specific. This is most easily tested by creating a FIB without a
+# default route, then trying to send a UDP packet with SO_DONTROUTE set to an
+# address which is not routable on that FIB. Absent the fix for this bug,
+# in_pcbladdr would choose an interface on any FIB with a default route. With
+# the fix, you will get EUNREACH or ENETUNREACH.
+atf_test_case udp_dontroute cleanup
+udp_dontroute_head()
{
atf_set "descr" "Source address selection for UDP packets with SO_DONTROUTE on non-default FIBs works"
atf_set "require.user" "root"
atf_set "require.config" "fibs"
}
-src_addr_selection_by_subnet_body()
+udp_dontroute_body()
{
atf_expect_fail "kern/187553 Source address selection for UDP packets with SO_DONTROUTE uses the default FIB"
# Configure the TAP interface to use an RFC5737 nonrouteable address
# and a non-default fib
- ADDR0="192.0.2.2"
- ADDR1="192.0.2.3"
- GATEWAY0="192.0.2.1"
- TARGET="192.0.2.128"
+ ADDR="192.0.2.2"
SUBNET="192.0.2.0"
- MASK0="25"
- MASK1="26"
+ MASK="24"
+ # Use a different IP on the same subnet as the target
+ TARGET="192.0.2.100"
# Check system configuration
if [ 0 != `sysctl -n net.add_addr_allfibs` ]; then
atf_skip "This test requires net.add_addr_allfibs=0"
fi
- get_fibs 2
+ get_fibs 1
# Configure a TAP interface
- setup_tap ${FIB0} ${ADDR0} ${MASK0}
- TAP0=${TAP}
- setup_tap ${FIB1} ${ADDR1} ${MASK1}
- TAP1=${TAP}
-
- # Add a gateway to the interface with the less specific subnet route
- setfib ${FIB0} route add default ${GATEWAY0}
+ setup_tap ${FIB0} ${ADDR} ${MASK}
- # Lookup a route
- echo "Looking up route to ${TARGET} with fib ${FIB0}"
- echo "Expected behavior is to use interface ${TAP0}"
- atf_check -o match:"interface:.${TAP0}" setfib ${FIB0} route -n get ${TARGET}
+ # Send a UDP packet with SO_DONTROUTE. In the failure case, it will
+ # return ENETUNREACH
+ SRCDIR=`atf_get_srcdir`
+ atf_check -o ignore setfib ${FIB0} ${SRCDIR}/udp_dontroute ${TARGET}
}
-src_addr_selection_by_subnet_cleanup()
+udp_dontroute_cleanup()
{
cleanup_tap
}
@@ -324,7 +310,7 @@ atf_init_test_cases()
atf_add_test_case loopback_and_network_routes_on_nondefault_fib
atf_add_test_case default_route_with_multiple_fibs_on_same_subnet
atf_add_test_case subnet_route_with_multiple_fibs_on_same_subnet
- atf_add_test_case src_addr_selection_by_subnet
+ atf_add_test_case udp_dontroute
}
# Looks up one or more fibs from the configuration data and validates them.
Copied: head/tests/sys/netinet/udp_dontroute.c (from r263737, head/tests/sys/netinet/udp_dontroute.c)
==============================================================================
--- /dev/null 00:00:00 1970 (empty, because file is newly added)
+++ head/tests/sys/netinet/udp_dontroute.c Thu Apr 24 23:56:56 2014 (r264905, copy of r263737, head/tests/sys/netinet/udp_dontroute.c)
@@ -0,0 +1,85 @@
+/*
+ * Copyright (c) 2014 Spectra Logic Corporation
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions, and the following disclaimer,
+ * without modification.
+ * 2. Redistributions in binary form must reproduce at minimum a disclaimer
+ * substantially similar to the "NO WARRANTY" disclaimer below
+ * ("Disclaimer") and any redistribution must be conditioned upon
+ * including a substantially similar Disclaimer requirement for further
+ * binary redistribution.
+ *
+ * NO WARRANTY
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
+ * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGES.
+ *
+ * Authors: Alan Somers (Spectra Logic Corporation)
+ *
+ * $FreeBSD$
+ */
+
+#include <arpa/inet.h>
+#include <netinet/in.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+
+#include <err.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+/*
+ * Sends a single UDP packet to the provided address, with SO_DONTROUTE set
+ * I couldn't find a way to do this with builtin utilities like nc(1)
+ */
+int main(int argc, char **argv)
+{
+ struct sockaddr_in dst;
+ int s;
+ int opt;
+ int ret;
+ const char* buf = "Hello, World!";
+
+ if (argc != 2) {
+ fprintf(stderr, "Usage: %s ip_address\n", argv[0]);
+ exit(2);
+ }
+ s = socket(PF_INET, SOCK_DGRAM, 0);
+ if (s < 0)
+ err(errno, "socket");
+ opt = 1;
+
+ ret = setsockopt(s, SOL_SOCKET, SO_DONTROUTE, &opt, sizeof(opt));
+ if (ret == -1)
+ err(errno, "setsockopt(SO_DONTROUTE)");
+
+ dst.sin_len = sizeof(dst);
+ dst.sin_family = AF_INET;
+ dst.sin_port = htons(46120);
+ dst.sin_addr.s_addr = inet_addr(argv[1]);
+ if (dst.sin_addr.s_addr == htonl(INADDR_NONE)) {
+ fprintf(stderr, "Invalid address: %s\n", argv[1]);
+ exit(2);
+ }
+ ret = sendto(s, buf, strlen(buf), 0, (struct sockaddr*)&dst,
+ dst.sin_len);
+ if (ret == -1)
+ err(errno, "sendto");
+
+ return (0);
+}
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