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Implement RFC-4388 DHCPv4 leasequery.

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This commit is contained in:
Simon Kelley
2025-03-20 15:59:55 +00:00
parent 57c7ae8fc0
commit 4fbe1add95
12 changed files with 1183 additions and 135 deletions
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32
src/dhcp.c
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@@ -135,7 +135,7 @@ void dhcp_packet(time_t now, int pxe_fd)
struct dhcp_packet *mess;
struct dhcp_context *context;
struct dhcp_relay *relay;
int is_relay_reply = 0;
int is_relay_reply = 0, is_relay_use_source = 0;
struct iname *tmp;
struct ifreq ifr;
struct msghdr msg;
@@ -231,7 +231,18 @@ void dhcp_packet(time_t now, int pxe_fd)
mess = (struct dhcp_packet *)daemon->dhcp_packet.iov_base;
loopback = !mess->giaddr.s_addr && (ifr.ifr_flags & IFF_LOOPBACK);
/* Non-standard extension:
If giaddr == 255.255.255.255 we reply to the source
address in the request packet header. This makes
stand-alone leasequery clients easier, as they
can leave source address determination to the kernel. */
if (mess->giaddr.s_addr == INADDR_BROADCAST)
{
mess->giaddr.s_addr = 0;
is_relay_use_source = 1;
}
#ifdef HAVE_LINUX_NETWORK
/* ARP fiddling uses original interface even if we pretend to use a different one. */
safe_strncpy(arp_req.arp_dev, ifr.ifr_name, sizeof(arp_req.arp_dev));
@@ -337,8 +348,8 @@ void dhcp_packet(time_t now, int pxe_fd)
return;
lease_prune(NULL, now); /* lose any expired leases */
iov.iov_len = dhcp_reply(parm.current, ifr.ifr_name, iface_index, (size_t)sz,
now, unicast_dest, loopback, &is_inform, pxe_fd, iface_addr, recvtime);
iov.iov_len = dhcp_reply(parm.current, ifr.ifr_name, iface_index, (size_t)sz, now, unicast_dest,
loopback, &is_inform, pxe_fd, iface_addr, recvtime, is_relay_use_source);
lease_update_file(now);
lease_update_dns(0);
@@ -365,11 +376,16 @@ void dhcp_packet(time_t now, int pxe_fd)
if (mess->ciaddr.s_addr != 0)
dest.sin_addr = mess->ciaddr;
}
else if (mess->giaddr.s_addr && !is_relay_reply)
if ((is_relay_use_source || mess->giaddr.s_addr) && !is_relay_reply)
{
/* Send to BOOTP relay */
dest.sin_port = htons(daemon->dhcp_server_port);
dest.sin_addr = mess->giaddr;
/* Send to BOOTP relay. */
if (is_relay_use_source)
mess->giaddr.s_addr = INADDR_BROADCAST;
else
{
dest.sin_addr = mess->giaddr;
dest.sin_port = htons(daemon->dhcp_server_port);
}
}
else if (mess->ciaddr.s_addr)
{