[systemd-devel] [PATCH] libsystemd-network: Prepend hardware type byte to client identifier

[Patrik Flykt]

Even though client identifiers SHOULD be treated as opaque objects by
DHCP servers, follow the recommendation of a hardware type field with
value 0x01 (ethernet) followed by the hardware address as described in
RFC 2132.
---

	Hi,

This change "fixes" the DHCP client identifier to use the internal
structure described in RFC 2132 by prepending a type byte to the id.
The type byte was left off initially by mistake, but no harm seems to
have been caused by this omission.

With this change wireshark can pretty-print the MAC address in the client
identifier and systemd-networkd will now use the same client id format
as everybody else.


Cheers,

	Patrik


 src/libsystemd-network/sd-dhcp-client.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/src/libsystemd-network/sd-dhcp-client.c b/src/libsystemd-network/sd-dhcp-client.c
index ce375dd..1a57939 100644
--- a/src/libsystemd-network/sd-dhcp-client.c
+++ b/src/libsystemd-network/sd-dhcp-client.c
@@ -46,7 +46,10 @@ struct sd_dhcp_client {
         size_t req_opts_allocated;
         size_t req_opts_size;
         be32_t last_addr;
-        struct ether_addr mac_addr;
+        struct {
+                uint8_t type;
+                struct ether_addr mac_addr;
+        } _packed_ client_id;
         uint32_t xid;
         usec_t start_time;
         uint16_t secs;
@@ -152,7 +155,8 @@ int sd_dhcp_client_set_mac(sd_dhcp_client *client,
                         addr->ether_addr_octet[4],
                         addr->ether_addr_octet[5]);
 
-        memcpy(&client->mac_addr, addr, ETH_ALEN);
+        memcpy(&client->client_id.mac_addr, addr, ETH_ALEN);
+        client->client_id.type = 0x01;
 
         return 0;
 }
@@ -233,7 +237,7 @@ static int client_message_init(sd_dhcp_client *client, DHCPMessage *message,
            refuse to issue an DHCP lease if 'secs' is set to zero */
         message->secs = htobe16(secs);
 
-        memcpy(&message->chaddr, &client->mac_addr, ETH_ALEN);
+        memcpy(&message->chaddr, &client->client_id.mac_addr, ETH_ALEN);
 
         if (client->state == DHCP_STATE_RENEWING ||
             client->state == DHCP_STATE_REBINDING)
@@ -242,7 +246,7 @@ static int client_message_init(sd_dhcp_client *client, DHCPMessage *message,
         /* Some DHCP servers will refuse to issue an DHCP lease if the Client
            Identifier option is not set */
         r = dhcp_option_append(opt, optlen, DHCP_OPTION_CLIENT_IDENTIFIER,
-                               ETH_ALEN, &client->mac_addr);
+                               sizeof(client->client_id), &client->client_id);
         if (r < 0)
                 return r;
 
@@ -852,8 +856,8 @@ static int client_handle_message(sd_dhcp_client *client, DHCPMessage *message,
                 return 0;
         }
 
-        if (memcmp(&message->chaddr[0], &client->mac_addr.ether_addr_octet,
-                   ETHER_ADDR_LEN)) {
+        if (memcmp(&message->chaddr[0], &client->client_id.mac_addr,
+                   ETH_ALEN)) {
                 log_dhcp_client(client, "received chaddr does not match "
                                 "expected: ignoring");
                 return 0;
-- 
1.8.5.2