From: Toke Høiland-Jørgensen <toke@redhat.com>
Date: Fri, 29 Oct 2021 10:24:33 +0000 (+0200)
Subject: sd-dhcp-server: fix address availability checks
X-Git-Tag: v250-rc1~380^2
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=cb3c06a02eea17999c4fd577d35be7c9d1745a91;p=thirdparty%2Fsystemd.git

sd-dhcp-server: fix address availability checks

The checks for finding a new available address in the pool were broken in two
ways: not using UINT32_TO_PTR() on hashmap lookups resulted in false negatives,
and the check wasn't skipping the server address if that was part of the pool.

Move the check for available addresses to a small helper function and fix both
issues, and also add a check to the REQUEST code for the server address.
---

diff --git a/src/libsystemd-network/sd-dhcp-server.c b/src/libsystemd-network/sd-dhcp-server.c
index 39ac5e86fa2..604c34fe155 100644
--- a/src/libsystemd-network/sd-dhcp-server.c
+++ b/src/libsystemd-network/sd-dhcp-server.c
@@ -875,6 +875,17 @@ static int dhcp_server_cleanup_expired_leases(sd_dhcp_server *server) {
         return 0;
 }
 
+static bool address_available(sd_dhcp_server *server, be32_t address) {
+        assert(server);
+
+        if (hashmap_contains(server->bound_leases_by_address, UINT32_TO_PTR(address)) ||
+            hashmap_contains(server->static_leases_by_address, UINT32_TO_PTR(address)) ||
+            address == server->address)
+                return false;
+
+        return true;
+}
+
 #define HASH_KEY SD_ID128_MAKE(0d,1d,fe,bd,f1,24,bd,b3,47,f1,dd,6e,73,21,93,30)
 
 int dhcp_server_handle_message(sd_dhcp_server *server, DHCPMessage *message, size_t length) {
@@ -943,8 +954,7 @@ int dhcp_server_handle_message(sd_dhcp_server *server, DHCPMessage *message, siz
                                 be32_t tmp_address;
 
                                 tmp_address = server->subnet | htobe32(server->pool_offset + (hash + i) % server->pool_size);
-                                if (!hashmap_contains(server->bound_leases_by_address, &tmp_address) &&
-                                    !hashmap_contains(server->static_leases_by_address, &tmp_address)) {
+                                if (address_available(server, tmp_address)) {
                                         address = tmp_address;
                                         break;
                                 }
@@ -1021,6 +1031,10 @@ int dhcp_server_handle_message(sd_dhcp_server *server, DHCPMessage *message, siz
                         address = req->message->ciaddr;
                 }
 
+                /* disallow our own address */
+                if (address == server->address)
+                        return 0;
+
                 pool_offset = get_pool_offset(server, address);
                 existing_lease_by_address = hashmap_get(server->bound_leases_by_address, UINT32_TO_PTR(address));