slirp: Reassign same address to same DHCP client

In case a client restarts a DHCP recovery without releasing its old
address, reassign the same address to prevent consuming free addresses
and moving away from the standard client address.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>

1 files changed, 4 insertions, 3 deletions

diff --git a/bootp.c b/bootp.c
index dc4670f..a120dbe 100644
--- a/bootp.c
+++ b/bootp.c
@@ -52,13 +52,14 @@ static const uint8_t rfc1533_cookie[] = { RFC1533_COOKIE };
 #define dprintf(fmt, ...)
 #endif
 
-static BOOTPClient *get_new_addr(struct in_addr *paddr)
+static BOOTPClient *get_new_addr(struct in_addr *paddr, const uint8_t *macaddr)
 {
     BOOTPClient *bc;
     int i;
 
     for (i = 0; i < NB_ADDR; i++) {
-        if (!bootp_clients[i].allocated)
+        bc = &bootp_clients[i];
+        if (!bc->allocated || !memcmp(macaddr, bc->macaddr, 6))
             goto found;
     }
     return NULL;
@@ -194,7 +195,7 @@ static void bootp_reply(const struct bootp_t *bp)
         }
         if (!bc) {
         new_addr:
-            bc = get_new_addr(&daddr.sin_addr);
+            bc = get_new_addr(&daddr.sin_addr, client_ethaddr);
             if (!bc) {
                 dprintf("no address left\n");
                 return;