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From 3d27384fc5f2a437b7bce128c8ba62e8d6e12df7 Mon Sep 17 00:00:00 2001
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From: Brian Haley <haleyb.dev@gmail.com>
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Date: Wed, 28 Aug 2019 16:13:23 -0400
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Subject: [PATCH] Change dhcp_release to use default address when no IP subnet
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matches
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Currently, dhcp_release will only send a 'fake' release
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when the address given is in the same subnet as an IP
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on the interface that was given.
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This doesn't work in an environment where dnsmasq is
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managing leases for remote subnets via a DHCP relay, as
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running dhcp_release locally will just cause it to
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silently exit without doing anything, leaving the lease
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in the database.
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Change it to use the default IP on the interface, as the
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dnsmasq source code at src/dhcp.c does, if no matching subnet
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IP is found, as a fall-back. This fixes an issue we are
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seeing in certain Openstack deployments where we are using
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dnsmasq to provision baremetal systems in a datacenter.
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While using Dbus might have seemed like an obvious solution,
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because of our extensive use of network namespaces (which
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Dbus doesn't support), this seemed like a better solution
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than creating system.d policy files for each dnsmasq we
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might spawn and using --enable-dbus=$id in order to isolate
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messages to specific dnsmasq instances.
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Signed-off-by: Brian Haley <haleyb.dev@gmail.com>
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(cherry picked from commit d9f882bea2806799bf3d1f73937f5e72d0bfc650)
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---
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contrib/lease-tools/dhcp_release.c | 12 +++++++++---
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1 file changed, 9 insertions(+), 3 deletions(-)
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diff --git a/contrib/lease-tools/dhcp_release.c b/contrib/lease-tools/dhcp_release.c
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index a51f04b..1dd8d32 100644
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--- a/contrib/lease-tools/dhcp_release.c
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+++ b/contrib/lease-tools/dhcp_release.c
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@@ -178,7 +178,7 @@ static int is_same_net(struct in_addr a, struct in_addr b, struct in_addr mask)
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return (a.s_addr & mask.s_addr) == (b.s_addr & mask.s_addr);
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}
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-static struct in_addr find_interface(struct in_addr client, int fd, unsigned int index)
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+static struct in_addr find_interface(struct in_addr client, int fd, unsigned int index, int ifrfd, struct ifreq *ifr)
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{
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struct sockaddr_nl addr;
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struct nlmsghdr *h;
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@@ -218,7 +218,13 @@ static struct in_addr find_interface(struct in_addr client, int fd, unsigned int
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for (h = (struct nlmsghdr *)iov.iov_base; NLMSG_OK(h, (size_t)len); h = NLMSG_NEXT(h, len))
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if (h->nlmsg_type == NLMSG_DONE)
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- exit(0);
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+ {
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+ /* No match found, return first address as src/dhcp.c code does */
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+ ifr->ifr_addr.sa_family = AF_INET;
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+ if (ioctl(ifrfd, SIOCGIFADDR, ifr) != -1)
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+ return ((struct sockaddr_in *)&ifr->ifr_addr)->sin_addr;
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+ exit(0);
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+ }
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else if (h->nlmsg_type == RTM_NEWADDR)
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{
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struct ifaddrmsg *ifa = NLMSG_DATA(h);
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@@ -284,7 +290,7 @@ int main(int argc, char **argv)
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}
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lease.s_addr = inet_addr(argv[2]);
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- server = find_interface(lease, nl, if_nametoindex(argv[1]));
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+ server = find_interface(lease, nl, if_nametoindex(argv[1]), fd, &ifr);
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memset(&packet, 0, sizeof(packet));
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--
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2.20.1
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