networkd: dhcp-server - allow configuration of the pool

The constraints we place on the pool is that it is a contiguous
sequence of addresses in the same subnet as the server address, not
including the subnet nor broadcast addresses, but possibly including
the server address itself. If the server address is included in the
pool it is (obviously) reserved and not handed out to clients.

6 files changed, 25 insertions, 1 deletions

diff --git a/man/systemd.network.xml b/man/systemd.network.xml
index ded2c0ceff..2fb4733494 100644
--- a/man/systemd.network.xml
+++ b/man/systemd.network.xml
@@ -684,6 +684,23 @@
     <variablelist class='network-directives'>
 
       <varlistentry>
+        <term><varname>PoolOffset=</varname></term>
+        <term><varname>PoolSize=</varname></term>
+
+        <listitem><para>Configures the pool of addresses to hand out. The pool
+        is a contiguous sequence of IP addresses in the subnet configured for
+        the server address, which does not include the subnet nor the broadcast
+        address. <varname>PoolOffset=</varname> takes the offset of the pool
+        from the start of subnet, or zero to use the default value.
+        <varname>PoolSize=</varname> takes the number of IP addresses in the
+        pool or zero to use the default value. By default the pool starts at
+        the first address after the subnet address and takes up the rest of
+        the subnet, excluding the broadcast address. If the pool includes
+        the server address (the default), this is reserved and not handed
+        out to clients.</para></listitem>
+      </varlistentry>
+
+      <varlistentry>
         <term><varname>DefaultLeaseTimeSec=</varname></term>
         <term><varname>MaxLeaseTimeSec=</varname></term>
 
diff --git a/src/network/networkd-link.c b/src/network/networkd-link.c
index c5434147ed..979f3115f6 100644
--- a/src/network/networkd-link.c
+++ b/src/network/networkd-link.c
@@ -742,7 +742,8 @@ static int link_enter_set_addresses(Link *link) {
                 }
 
                 /* use the server address' subnet as the pool */
-                r = sd_dhcp_server_configure_pool(link->dhcp_server, &address->in_addr.in, address->prefixlen, 0, 0);
+                r = sd_dhcp_server_configure_pool(link->dhcp_server, &address->in_addr.in, address->prefixlen,
+                                                  link->network->dhcp_server_pool_offset, link->network->dhcp_server_pool_size);
                 if (r < 0)
                         return r;
 
diff --git a/src/network/networkd-network-gperf.gperf b/src/network/networkd-network-gperf.gperf
index 108e892fb8..10ca9dae35 100644
--- a/src/network/networkd-network-gperf.gperf
+++ b/src/network/networkd-network-gperf.gperf
@@ -82,6 +82,8 @@ DHCPServer.EmitNTP,            config_parse_bool,                              0
 DHCPServer.NTP,                config_parse_dhcp_server_ntp,                   0,                             0
 DHCPServer.EmitTimezone,       config_parse_bool,                              0,                             offsetof(Network, dhcp_server_emit_timezone)
 DHCPServer.Timezone,           config_parse_timezone,                          0,                             offsetof(Network, dhcp_server_timezone)
+DHCPServer.PoolOffset,         config_parse_uint32,                            0,                             offsetof(Network, dhcp_server_pool_offset)
+DHCPServer.PoolSize,           config_parse_uint32,                            0,                             offsetof(Network, dhcp_server_pool_size)
 Bridge.Cost,                   config_parse_unsigned,                          0,                             offsetof(Network, cost)
 Bridge.UseBPDU,                config_parse_bool,                              0,                             offsetof(Network, use_bpdu)
 Bridge.HairPin,                config_parse_bool,                              0,                             offsetof(Network, hairpin)
diff --git a/src/network/networkd-network.h b/src/network/networkd-network.h
index d691cc3a45..c3439a70ba 100644
--- a/src/network/networkd-network.h
+++ b/src/network/networkd-network.h
@@ -102,6 +102,8 @@ struct Network {
         bool dhcp_server_emit_timezone;
         char *dhcp_server_timezone;
         usec_t dhcp_server_default_lease_time_usec, dhcp_server_max_lease_time_usec;
+        uint32_t dhcp_server_pool_offset;
+        uint32_t dhcp_server_pool_size;
 
         /* IPV4LL Support */
         AddressFamilyBoolean link_local;
diff --git a/src/shared/conf-parser.c b/src/shared/conf-parser.c
index d99aa1d6e9..1f4aea6d6b 100644
--- a/src/shared/conf-parser.c
+++ b/src/shared/conf-parser.c
@@ -450,6 +450,7 @@ int config_parse_many(const char *conf_file,
 
 DEFINE_PARSER(int, int, safe_atoi)
 DEFINE_PARSER(long, long, safe_atoli)
+DEFINE_PARSER(uint32, uint32_t, safe_atou32)
 DEFINE_PARSER(uint64, uint64_t, safe_atou64)
 DEFINE_PARSER(unsigned, unsigned, safe_atou)
 DEFINE_PARSER(double, double, safe_atod)
diff --git a/src/shared/conf-parser.h b/src/shared/conf-parser.h
index 6152ee33b9..66c80890d3 100644
--- a/src/shared/conf-parser.h
+++ b/src/shared/conf-parser.h
@@ -104,6 +104,7 @@ int config_parse_many(const char *conf_file,      /* possibly NULL */
 int config_parse_int(const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);
 int config_parse_unsigned(const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);
 int config_parse_long(const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);
+int config_parse_uint32(const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);
 int config_parse_uint64(const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);
 int config_parse_double(const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line,  const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);
 int config_parse_iec_size(const char *unit, const char *filename, unsigned line, const char *section, unsigned section_line, const char *lvalue, int ltype, const char *rvalue, void *data, void *userdata);