dhcp4: fix DHCP on InfiniBand interfaces

With these patches applied, networkd is successfully able to get an
address from a DHCP server on an IPoIB interface.

1)
Makes networkd pass the actual interface type to the dhcp client,
instead of hardcoding it to Ethernet.

2)
Fixes some issues in handling the larger (20 Byte) IB MAC addresses in
the dhcp code.

3)
Add a new field to networkds Link struct, which holds the interface
broadcast address.

3.1)
Modify the DHCP code to also expect the broadcast address as parameter.
On an Ethernet-Interface the Broadcast address never changes and is always
all 6 bytes set to 0xFF.
On an IB one however it is not neccesarily always the same, thus
fetching the actual address from the interface is neccesary.

4)
Only the last 8 bytes of an IB MAC are stable, so when using an IB MAC to
generate a client ID, only pass those 8 bytes.

1 files changed, 19 insertions, 6 deletions

diff --git a/src/network/networkd-dhcp4.c b/src/network/networkd-dhcp4.c
index 5255ec3e1c..319ef61593 100644
--- a/src/network/networkd-dhcp4.c
+++ b/src/network/networkd-dhcp4.c
@@ -1271,14 +1271,24 @@ static int dhcp4_set_client_identifier(Link *link) {
                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set DUID: %m");
                 break;
         }
-        case DHCP_CLIENT_ID_MAC:
+        case DHCP_CLIENT_ID_MAC: {
+                const uint8_t *hw_addr = link->hw_addr.addr.bytes;
+                size_t hw_addr_len = link->hw_addr.length;
+
+                if (link->iftype == ARPHRD_INFINIBAND && hw_addr_len == INFINIBAND_ALEN) {
+                        /* set_client_id expects only last 8 bytes of an IB address */
+                        hw_addr += INFINIBAND_ALEN - 8;
+                        hw_addr_len -= INFINIBAND_ALEN - 8;
+                }
+
                 r = sd_dhcp_client_set_client_id(link->dhcp_client,
-                                                 ARPHRD_ETHER,
-                                                 link->hw_addr.addr.bytes,
-                                                 link->hw_addr.length);
+                                                 link->iftype,
+                                                 hw_addr,
+                                                 hw_addr_len);
                 if (r < 0)
                         return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set client ID: %m");
                 break;
+        }
         default:
                 assert_not_reached("Unknown client identifier type.");
         }
@@ -1326,7 +1336,8 @@ int dhcp4_configure(Link *link) {
 
         r = sd_dhcp_client_set_mac(link->dhcp_client,
                                    link->hw_addr.addr.bytes,
-                                   link->hw_addr.length, ARPHRD_ETHER);
+                                   link->bcast_addr.length > 0 ? link->bcast_addr.addr.bytes : NULL,
+                                   link->hw_addr.length, link->iftype);
         if (r < 0)
                 return log_link_error_errno(link, r, "DHCP4 CLIENT: Failed to set MAC address: %m");
 
@@ -1484,7 +1495,9 @@ int dhcp4_update_mac(Link *link) {
         if (!link->dhcp_client)
                 return 0;
 
-        r = sd_dhcp_client_set_mac(link->dhcp_client, link->hw_addr.addr.bytes, link->hw_addr.length, ARPHRD_ETHER);
+        r = sd_dhcp_client_set_mac(link->dhcp_client, link->hw_addr.addr.bytes,
+                                   link->bcast_addr.length > 0 ? link->bcast_addr.addr.bytes : NULL,
+                                   link->hw_addr.length, link->iftype);
         if (r < 0)
                 return r;