[systemd-devel] [PATCH] resolved: re-add support for getting local domain from DHCP

[Michael Marineau]

When the code for generating resolv.conf was moved from networkd to
resolved the DHCP domain name code was dropped.
---

This is a resend, rebased since some recent changes changed how this
patch needed to be implemented.

 src/network/networkd-link.c    | 13 +++++++++++++
 src/network/sd-network.c       | 24 ++++++++++++++++++++++++
 src/resolve/resolved-link.c    | 20 ++++++++++++++++++++
 src/resolve/resolved-link.h    |  2 ++
 src/resolve/resolved-manager.c | 10 +++++++++-
 src/systemd/sd-network.h       |  3 +++
 6 files changed, 71 insertions(+), 1 deletion(-)

diff --git a/src/network/networkd-link.c b/src/network/networkd-link.c
index 3b8b7ed..827c428 100644
--- a/src/network/networkd-link.c
+++ b/src/network/networkd-link.c
@@ -2451,6 +2451,19 @@ int link_save(Link *link) {
                                 (address + 1 ? " " : ""));
 
                 fputs("\n", f);
+
+                fprintf(f, "DOMAINNAME=");
+
+                if (link->network->dhcp_domainname &&
+                    link->dhcp_lease) {
+                        const char *domainname;
+
+                        r = sd_dhcp_lease_get_domainname(link->dhcp_lease, &domainname);
+                        if (r >= 0)
+                                fputs(domainname, f);
+                }
+
+                fputs("\n", f);
         }
 
         if (link->dhcp_lease) {
diff --git a/src/network/sd-network.c b/src/network/sd-network.c
index bfb8321..a427a27 100644
--- a/src/network/sd-network.c
+++ b/src/network/sd-network.c
@@ -175,6 +175,30 @@ _public_ int sd_network_get_ntp(int ifindex, char ***ret) {
         return network_get_strv("NTP", ifindex, ret);
 }
 
+_public_ int sd_network_get_domainname(int ifindex, char **domainname) {
+        _cleanup_free_ char *s = NULL, *p = NULL;
+        int r;
+
+        assert_return(ifindex > 0, -EINVAL);
+        assert_return(domainname, -EINVAL);
+
+        if (asprintf(&p, "/run/systemd/netif/links/%d", ifindex) < 0)
+                return -ENOMEM;
+
+        r = parse_env_file(p, NEWLINE, "DOMAINNAME", &s, NULL);
+        if (r == -ENOENT)
+                return -ENODATA;
+        else if (r < 0)
+                return r;
+        else if (!s)
+                return -EIO;
+
+        *domainname = s;
+        s = NULL;
+
+        return 0;
+}
+
 static inline int MONITOR_TO_FD(sd_network_monitor *m) {
         return (int) (unsigned long) m - 1;
 }
diff --git a/src/resolve/resolved-link.c b/src/resolve/resolved-link.c
index 6ac7c5b..f6b7f6a 100644
--- a/src/resolve/resolved-link.c
+++ b/src/resolve/resolved-link.c
@@ -77,6 +77,7 @@ Link *link_free(Link *l) {
         while (l->dns_servers)
                 dns_server_free(l->dns_servers);
 
+        free(l->domainname);
         free(l);
         return NULL;
 }
@@ -191,10 +192,29 @@ clear:
         return r;
 }
 
+static int link_update_domainname(Link *l) {
+        char *domainname = NULL;
+        int r;
+
+        assert(l);
+
+        free(l->domainname);
+        l->domainname = NULL;
+
+        r = sd_network_get_domainname(l->ifindex, &domainname);
+        if (r < 0)
+                return r;
+
+        l->domainname = domainname;
+
+        return 0;
+}
+
 int link_update_monitor(Link *l) {
         assert(l);
 
         link_update_dns_servers(l);
+        link_update_domainname(l);
         link_allocate_scopes(l);
         link_add_rrs(l);
 
diff --git a/src/resolve/resolved-link.h b/src/resolve/resolved-link.h
index f58bd54..9730aec 100644
--- a/src/resolve/resolved-link.h
+++ b/src/resolve/resolved-link.h
@@ -68,6 +68,8 @@ struct Link {
 
         RateLimit mdns_ratelimit;
         RateLimit llmnr_ratelimit;
+
+        char *domainname;
 };
 
 int link_new(Manager *m, Link **ret, int ifindex);
diff --git a/src/resolve/resolved-manager.c b/src/resolve/resolved-manager.c
index a8715bd..253a97e 100644
--- a/src/resolve/resolved-manager.c
+++ b/src/resolve/resolved-manager.c
@@ -522,6 +522,7 @@ int manager_write_resolv_conf(Manager *m) {
         const char *path = "/run/systemd/resolve/resolv.conf";
         _cleanup_free_ char *temp_path = NULL;
         _cleanup_fclose_ FILE *f = NULL;
+        const char *domainname = NULL;
         unsigned count = 0;
         DnsServer *s;
         Iterator i;
@@ -542,13 +543,20 @@ int manager_write_resolv_conf(Manager *m) {
               "# resolv.conf(5) in a different way, replace the symlink by a\n"
               "# static file or a different symlink.\n\n", f);
 
-        HASHMAP_FOREACH(l, m->links, i)
+        HASHMAP_FOREACH(l, m->links, i) {
                 LIST_FOREACH(servers, s, l->dns_servers)
                         write_resolve_conf_server(s, f, &count);
 
+                if (!domainname && l->domainname)
+                        domainname = l->domainname;
+        }
+
         LIST_FOREACH(servers, s, m->dns_servers)
                 write_resolve_conf_server(s, f, &count);
 
+        if (domainname)
+                fprintf(f, "domain %s\n", domainname);
+
         r = fflush_and_check(f);
         if (r < 0)
                 goto fail;
diff --git a/src/systemd/sd-network.h b/src/systemd/sd-network.h
index ec01e07..06f147d 100644
--- a/src/systemd/sd-network.h
+++ b/src/systemd/sd-network.h
@@ -84,6 +84,9 @@ int sd_network_get_dns(int ifindex, char ***addr);
  * reperesentations of IP addresses */
 int sd_network_get_ntp(int ifindex, char ***addr);
 
+/* Get the DNS domain name for a given link. */
+int sd_network_get_domainname(int ifindex, char **domainname);
+
 /* Monitor object */
 typedef struct sd_network_monitor sd_network_monitor;
 
-- 
1.8.5.5