init: embed a simple DHCP client

If there's a eth0 interface present, and one of the interfaces has been
configured with the newly introduced NET_FLAG_DHCP_CLIENT flag, the
embedded dhcp client will try to obtain an address.

For 2.x we should be more flexible and actually allow both dhcp and
static IP configuration on specific interfaces (identified by their
MAC addresses, since ifnames aren't deterministic), but this should
be good enough for 1.x.

Signed-off-by: Sergio Lopez <[email protected]>

Author: slp

include/libkrun.h

@@ -354,7 +354,8 @@ int32_t krun_add_virtiofs3(uint32_t ctx_id,
 
 /* Send the VFKIT magic after establishing the connection,
    as required by gvproxy in vfkit mode. */
-#define NET_FLAG_VFKIT 1 << 0
+#define NET_FLAG_VFKIT (1 << 0)
+#define NET_FLAG_DHCP_CLIENT (1 << 1)
 
 /* TSI (Transparent Socket Impersonation) feature flags for vsock */
 #define KRUN_TSI_HIJACK_INET  (1 << 0)