From d4b37f7a7b4d7ee2f8c23d63093ac32810bf0621 Mon Sep 17 00:00:00 2001
From: Daniel Wang <wonderfly@google.com>
Date: Mon, 6 Mar 2017 15:35:13 -0800
Subject: [PATCH 1/1] libsystemd-networkd: use single-label hostname.

---
 src/libsystemd-network/sd-dhcp-lease.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/src/libsystemd-network/sd-dhcp-lease.c b/src/libsystemd-network/sd-dhcp-lease.c
index 8387b185c..2d60d4223 100644
--- a/src/libsystemd-network/sd-dhcp-lease.c
+++ b/src/libsystemd-network/sd-dhcp-lease.c
@@ -141,12 +141,27 @@ int sd_dhcp_lease_get_domainname(sd_dhcp_lease *lease, const char **domainname)
 }
 
 int sd_dhcp_lease_get_hostname(sd_dhcp_lease *lease, const char **hostname) {
+        char *firstdot = NULL;
+
         assert_return(lease, -EINVAL);
         assert_return(hostname, -EINVAL);
 
         if (!lease->hostname)
                 return -ENODATA;
 
+        // Lakitu-specific behavior: always use single-label hostname
+        // or unqualified domain-name instead of FQDN.
+        // Lakitu configures systemd-networkd to set the hostname via
+        // DHCP. RFC 1497 says the DHCP server may send a
+        // fully-qualified domain name as the hostname.  The FQDN can
+        // be 255 bytes long, but the hostname on Linux is typically
+        // limited to 64 bytes.  To avoid dropping the FQDN as
+        // "invalid" for its length, we mutate |hostname| such that it
+        // contains only the single-label hostname.
+        if ((firstdot = strchr(lease->hostname, '.')) != NULL) {
+            *firstdot = 0;
+        }
+
         *hostname = lease->hostname;
         return 0;
 }
-- 
2.12.0.rc1.440.g5b76565f74-goog