Merge pull request #19611 from yuwata/network-dhcp-server-introduce-server-address

network: dhcp-server: introduce ServerAddress= setting

1 files changed, 97 insertions, 34 deletions

diff --git a/src/network/networkd-address.c b/src/network/networkd-address.c
index daf959ec5f..2bc860954b 100644
--- a/src/network/networkd-address.c
+++ b/src/network/networkd-address.c
@@ -146,12 +146,38 @@ Address *address_free(Address *address) {
 static bool address_may_have_broadcast(const Address *a) {
         assert(a);
 
+        if (a->family != AF_INET)
+                return false;
+
+        if (in4_addr_is_set(&a->in_addr_peer.in))
+                return false;
+
         /* A /31 or /32 IPv4 address does not have a broadcast address.
          * See https://tools.ietf.org/html/rfc3021 */
+        if (a->prefixlen > 30)
+                return false;
+
+        if (a->set_broadcast >= 0)
+                return a->set_broadcast;
+
+        return true; /* Defaults to true. */
+}
+
+void address_set_broadcast(Address *a) {
+        assert(a);
+
+        if (!address_may_have_broadcast(a))
+                return;
 
-        return a->family == AF_INET &&
-                in4_addr_is_null(&a->in_addr_peer.in) &&
-                a->prefixlen <= 30;
+        /* If explicitly configured, do not update the address. */
+        if (in4_addr_is_set(&a->broadcast))
+                return;
+
+        /* If Address= is 0.0.0.0, then the broadcast address will be set later in address_acquire(). */
+        if (in4_addr_is_null(&a->in_addr.in))
+                return;
+
+        a->broadcast.s_addr = a->in_addr.in.s_addr | htobe32(UINT32_C(0xffffffff) >> a->prefixlen);
 }
 
 static bool address_may_set_broadcast(const Address *a, const Link *link) {
@@ -161,9 +187,6 @@ static bool address_may_set_broadcast(const Address *a, const Link *link) {
         if (!address_may_have_broadcast(a))
                 return false;
 
-        if (a->set_broadcast >= 0)
-                return a->set_broadcast;
-
         /* Typical configuration for wireguard does not set broadcast. */
         return !streq_ptr(link->kind, "wireguard");
 }
@@ -466,7 +489,7 @@ int address_get(Link *link, const Address *in, Address **ret) {
         return -ENOENT;
 }
 
-int link_has_ipv6_address(Link *link, const struct in6_addr *address) {
+int link_get_ipv6_address(Link *link, const struct in6_addr *address, Address **ret) {
         _cleanup_(address_freep) Address *a = NULL;
         int r;
 
@@ -482,10 +505,10 @@ int link_has_ipv6_address(Link *link, const struct in6_addr *address) {
         a->family = AF_INET6;
         a->in_addr.in6 = *address;
 
-        return address_get(link, a, NULL) >= 0;
+        return address_get(link, a, ret);
 }
 
-static int link_get_ipv4_address(Set *addresses, const struct in_addr *address, Address **ret) {
+static int addresses_get_ipv4_address(Set *addresses, const struct in_addr *address, Address **ret) {
         Address *a;
 
         assert(address);
@@ -506,7 +529,35 @@ static int link_get_ipv4_address(Set *addresses, const struct in_addr *address,
         return -ENOENT;
 }
 
+int link_get_ipv4_address(Link *link, const struct in_addr *address, unsigned char prefixlen, Address **ret) {
+        int r;
+
+        assert(link);
+        assert(address);
+
+        if (prefixlen != 0) {
+                _cleanup_(address_freep) Address *a = NULL;
+
+                /* If prefixlen is set, then we can use address_get(). */
+
+                r = address_new(&a);
+                if (r < 0)
+                        return r;
+
+                a->family = AF_INET;
+                a->in_addr.in = *address;
+                a->prefixlen = prefixlen;
+
+                return address_get(link, a, ret);
+        }
+
+        if (addresses_get_ipv4_address(link->addresses, address, ret) >= 0)
+                return 0;
+        return addresses_get_ipv4_address(link->addresses_foreign, address, ret);
+}
+
 int manager_has_address(Manager *manager, int family, const union in_addr_union *address, bool check_ready) {
+        Address *a;
         Link *link;
         int r;
 
@@ -514,18 +565,12 @@ int manager_has_address(Manager *manager, int family, const union in_addr_union
         assert(IN_SET(family, AF_INET, AF_INET6));
         assert(address);
 
-        if (family == AF_INET)
-                HASHMAP_FOREACH(link, manager->links) {
-                        Address *a;
-
-                        if (link_get_ipv4_address(link->addresses, &address->in, &a) >= 0)
-                                return !check_ready || address_is_ready(a);
-                        if (link_get_ipv4_address(link->addresses_foreign, &address->in, &a) >= 0)
+        if (family == AF_INET) {
+                HASHMAP_FOREACH(link, manager->links)
+                        if (link_get_ipv4_address(link, &address->in, 0, &a) >= 0)
                                 return !check_ready || address_is_ready(a);
-                }
-        else {
+        } else {
                 _cleanup_(address_freep) Address *tmp = NULL;
-                Address *a;
 
                 r = address_new(&tmp);
                 if (r < 0)
@@ -825,7 +870,6 @@ int link_drop_addresses(Link *link) {
 
 static int address_acquire(Link *link, const Address *original, Address **ret) {
         union in_addr_union in_addr = IN_ADDR_NULL;
-        struct in_addr broadcast = {};
         _cleanup_(address_freep) Address *na = NULL;
         int r;
 
@@ -847,16 +891,10 @@ static int address_acquire(Link *link, const Address *original, Address **ret) {
         if (r == 0)
                 return -EBUSY;
 
-        if (original->family == AF_INET) {
-                /* Pick first address in range for ourselves ... */
+        /* Pick first address in range for ourselves. */
+        if (original->family == AF_INET)
                 in_addr.in.s_addr = in_addr.in.s_addr | htobe32(1);
-
-                /* .. and use last as broadcast address */
-                if (original->prefixlen > 30)
-                        broadcast.s_addr = 0;
-                else
-                        broadcast.s_addr = in_addr.in.s_addr | htobe32(0xFFFFFFFFUL >> original->prefixlen);
-        } else if (original->family == AF_INET6)
+        else if (original->family == AF_INET6)
                 in_addr.in6.s6_addr[15] |= 1;
 
         r = address_new(&na);
@@ -867,8 +905,8 @@ static int address_acquire(Link *link, const Address *original, Address **ret) {
         if (r < 0)
                 return r;
 
-        na->broadcast = broadcast;
         na->in_addr = in_addr;
+        address_set_broadcast(na);
 
         r = set_ensure_put(&link->pool_addresses, &address_hash_ops, na);
         if (r < 0)
@@ -1119,6 +1157,32 @@ int link_request_static_addresses(Link *link) {
                 req->after_configure = static_address_after_configure;
         }
 
+        if (in4_addr_is_set(&link->network->dhcp_server_address)) {
+                _cleanup_(address_freep) Address *address = NULL;
+
+                r = address_new(&address);
+                if (r < 0)
+                        return log_oom();
+
+                address->family = AF_INET;
+                address->in_addr.in = link->network->dhcp_server_address;
+                address->prefixlen = link->network->dhcp_server_address_prefixlen;
+                address_set_broadcast(address);
+
+                /* The same address may be explicitly configured in [Address] or [Network] section.
+                 * Configure the DHCP server address only when it is not. */
+                if (!link_is_static_address_configured(link, address)) {
+                        Request *req;
+
+                        r = link_request_address(link, TAKE_PTR(address), true, &link->static_address_messages,
+                                                 static_address_handler, &req);
+                        if (r < 0)
+                                return r;
+
+                        req->after_configure = static_address_after_configure;
+                }
+        }
+
         if (link->static_address_messages == 0) {
                 link->static_addresses_configured = true;
                 link_check_ready(link);
@@ -1960,10 +2024,9 @@ static int address_section_verify(Address *address) {
                                          address->section->filename, address->section->line);
         }
 
-        if (address_may_have_broadcast(address)) {
-                if (address->broadcast.s_addr == 0 && address->set_broadcast != 0)
-                        address->broadcast.s_addr = address->in_addr.in.s_addr | htobe32(0xfffffffflu >> address->prefixlen);
-        } else if (address->broadcast.s_addr != 0) {
+        if (address_may_have_broadcast(address))
+                address_set_broadcast(address);
+        else if (address->broadcast.s_addr != 0) {
                 log_warning("%s: broadcast address is set for IPv6 address or IPv4 address with prefixlength larger than 30. "
                             "Ignoring Broadcast= setting in the [Address] section from line %u.",
                             address->section->filename, address->section->line);