sd-dhcp: generalise ip header generation

This will be needed for sd-dhcp-server.

3 files changed, 27 insertions, 16 deletions

diff --git a/src/libsystemd-network/dhcp-internal.h b/src/libsystemd-network/dhcp-internal.h
index ce83b81631..3c3e1f649f 100644
--- a/src/libsystemd-network/dhcp-internal.h
+++ b/src/libsystemd-network/dhcp-internal.h
@@ -48,7 +48,9 @@ int dhcp_option_parse(DHCPMessage *message, size_t len,
 int dhcp_message_init(DHCPMessage *message, uint8_t op, uint32_t xid, uint8_t type,
                       uint8_t **opt, size_t *optlen);
 
-void dhcp_packet_append_ip_headers(DHCPPacket *packet, uint16_t len);
+void dhcp_packet_append_ip_headers(DHCPPacket *packet, be32_t source_addr,
+                                   uint16_t source, be32_t destination_addr,
+                                   uint16_t destination, uint16_t len);
 
 int dhcp_packet_verify_headers(DHCPPacket *packet, size_t len, bool checksum);
 
diff --git a/src/libsystemd-network/dhcp-packet.c b/src/libsystemd-network/dhcp-packet.c
index 95c4277f8c..418a9773f2 100644
--- a/src/libsystemd-network/dhcp-packet.c
+++ b/src/libsystemd-network/dhcp-packet.c
@@ -92,17 +92,19 @@ static uint16_t dhcp_checksum(void *buf, int len) {
         return ~sum;
 }
 
-void dhcp_packet_append_ip_headers(DHCPPacket *packet, uint16_t len) {
+void dhcp_packet_append_ip_headers(DHCPPacket *packet, be32_t source_addr,
+                                   uint16_t source_port, be32_t destination_addr,
+                                   uint16_t destination_port, uint16_t len) {
         packet->ip.version = IPVERSION;
         packet->ip.ihl = DHCP_IP_SIZE / 4;
         packet->ip.tot_len = htobe16(len);
 
         packet->ip.protocol = IPPROTO_UDP;
-        packet->ip.saddr = INADDR_ANY;
-        packet->ip.daddr = INADDR_BROADCAST;
+        packet->ip.saddr = source_addr;
+        packet->ip.daddr = destination_addr;
 
-        packet->udp.source = htobe16(DHCP_PORT_CLIENT);
-        packet->udp.dest = htobe16(DHCP_PORT_SERVER);
+        packet->udp.source = htobe16(source_port);
+        packet->udp.dest = htobe16(destination_port);
 
         packet->udp.len = htobe16(len - DHCP_IP_SIZE);
 
diff --git a/src/libsystemd-network/sd-dhcp-client.c b/src/libsystemd-network/sd-dhcp-client.c
index 07b27d5393..e0fce5b5ad 100644
--- a/src/libsystemd-network/sd-dhcp-client.c
+++ b/src/libsystemd-network/sd-dhcp-client.c
@@ -264,6 +264,15 @@ static int client_message_init(sd_dhcp_client *client, DHCPMessage *message,
         return 0;
 }
 
+static int dhcp_client_send_raw(sd_dhcp_client *client, DHCPPacket *packet,
+                                size_t len) {
+        dhcp_packet_append_ip_headers(packet, INADDR_ANY, DHCP_PORT_CLIENT,
+                                      INADDR_BROADCAST, DHCP_PORT_SERVER, len);
+
+        return dhcp_network_send_raw_socket(client->fd, &client->link,
+                                            packet, len);
+}
+
 static int client_send_discover(sd_dhcp_client *client, uint16_t secs) {
         int err = 0;
         _cleanup_free_ DHCPPacket *discover;
@@ -295,14 +304,13 @@ static int client_send_discover(sd_dhcp_client *client, uint16_t secs) {
         if (err < 0)
                 return err;
 
-        dhcp_packet_append_ip_headers(discover, len);
-
-        err = dhcp_network_send_raw_socket(client->fd, &client->link,
-                                           discover, len);
+        err = dhcp_client_send_raw(client, discover, len);
+        if (err < 0)
+                return err;
 
         log_dhcp_client(client, "DISCOVER");
 
-        return err;
+        return 0;
 }
 
 static int client_send_request(sd_dhcp_client *client, uint16_t secs) {
@@ -348,15 +356,14 @@ static int client_send_request(sd_dhcp_client *client, uint16_t secs) {
                                                    &request->dhcp,
                                                    len - DHCP_IP_UDP_SIZE);
         } else {
-                dhcp_packet_append_ip_headers(request, len);
-
-                err = dhcp_network_send_raw_socket(client->fd, &client->link,
-                                                   request, len);
+                err = dhcp_client_send_raw(client, request, len);
         }
+        if (err < 0)
+                return err;
 
         log_dhcp_client(client, "REQUEST");
 
-        return err;
+        return 0;
 }
 
 static uint16_t client_update_secs(sd_dhcp_client *client, usec_t time_now)