slirp: Add domain-search option to slirp's DHCP server

This patch will allow the user to include the domain-search option in
replies from the built-in DHCP server. The domain suffixes can be
specified by adding dnssearch= entries to the "-net user" parameter.

[Jan: tiny style adjustments]

Signed-off-by: Klaus Stengel <Klaus.Stengel@asamnet.de>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/slirp/bootp.c b/slirp/bootp.c
index 64eac7d101..b7db9fa335 100644
--- a/slirp/bootp.c
+++ b/slirp/bootp.c
@@ -287,6 +287,18 @@ static void bootp_reply(Slirp *slirp, const struct bootp_t *bp)
             memcpy(q, slirp->client_hostname, val);
             q += val;
         }
+
+        if (slirp->vdnssearch) {
+            size_t spaceleft = sizeof(rbp->bp_vend) - (q - rbp->bp_vend);
+            val = slirp->vdnssearch_len;
+            if (val + 1 > spaceleft) {
+                g_warning("DHCP packet size exceeded, "
+                    "omitting domain-search option.");
+            } else {
+                memcpy(q, slirp->vdnssearch, val);
+                q += val;
+            }
+        }
     } else {
         static const char nak_msg[] = "requested address not available";