s3: Cache the username map in gencache

This is for uses with a heavy-weight username map script

docs-xml/smbdotconf/security/usernamemapcachetime.xml

@@ -0,0 +1,18 @@
+<samba:parameter name="username map cache time"
+                 context="G"
+                 advanced="1" developer="0"
+				 type="integer"
+                 xmlns:samba="http://www.samba.org/samba/DTD/samba-doc">
+<description>
+    <para>This option controls if and how long the result of the
+      <smbconfoption name="username map"/> and
+      <smbconfoption name="username map script"/> across smbds in gencache.
+      If set to non-zero, it denotes the number of seconds the output of
+      both mappings will be cached.</para>
+    <para>This option is mainly useful for heavy-weight
+      <smbconfoption name="username map script"/> scripts.</para>
+</description>
+
+<value type="default">0</value>
+<value type="example">60</value>
+</samba:parameter>

source3/include/proto.h

@@ -3998,6 +3998,7 @@ char *lp_addmachine_script(void);
 char *lp_shutdown_script(void);
 char *lp_abort_shutdown_script(void);
 char *lp_username_map_script(void);
+int lp_username_map_cache_time(void);
 char *lp_check_password_script(void);
 char *lp_wins_hook(void);
 const char *lp_template_homedir(void);

source3/param/loadparm.c

@@ -181,6 +181,7 @@ struct global {
 	char *szShutdownScript;
 	char *szAbortShutdownScript;
 	char *szUsernameMapScript;
+	int iUsernameMapCacheTime;
 	char *szCheckPasswordScript;
 	char *szWINSHook;
 	char *szUtmpDir;
@@ -3290,6 +3291,15 @@ static struct parm_struct parm_table[] = {
 		.enum_list	= NULL,
 		.flags		= FLAG_ADVANCED,
 	},
+	{
+		.label		= "username map cache time",
+		.type		= P_INTEGER,
+		.p_class	= P_GLOBAL,
+		.ptr		= &Globals.iUsernameMapCacheTime,
+		.special	= NULL,
+		.enum_list	= NULL,
+		.flags		= FLAG_ADVANCED,
+	},
 	{
 		.label		= "logon script",
 		.type		= P_STRING,
@@ -5494,6 +5504,7 @@ FN_GLOBAL_STRING(lp_addmachine_script, &Globals.szAddMachineScript)
 FN_GLOBAL_STRING(lp_shutdown_script, &Globals.szShutdownScript)
 FN_GLOBAL_STRING(lp_abort_shutdown_script, &Globals.szAbortShutdownScript)
 FN_GLOBAL_STRING(lp_username_map_script, &Globals.szUsernameMapScript)
+FN_GLOBAL_INTEGER(lp_username_map_cache_time, &Globals.iUsernameMapCacheTime)
 
 FN_GLOBAL_STRING(lp_check_password_script, &Globals.szCheckPasswordScript)
 

source3/smbd/map_username.c

@@ -76,6 +76,48 @@ static char *skip_space(char *s)
 	return s;
 }
 
+static bool fetch_map_from_gencache(fstring user)
+{
+	char *key, *value;
+	bool found;
+
+	if (lp_username_map_cache_time() == 0) {
+		return false;
+	}
+
+	key = talloc_asprintf_strupper_m(talloc_tos(), "USERNAME_MAP/%s",
+					 user);
+	if (key == NULL) {
+		return false;
+	}
+	found = gencache_get(key, &value, NULL);
+	TALLOC_FREE(key);
+	if (!found) {
+		return false;
+	}
+	fstrcpy(user, value);
+	SAFE_FREE(value);
+	return true;
+}
+
+static void store_map_in_gencache(const char *from, const char *to)
+{
+	char *key;
+	int cache_time = lp_username_map_cache_time();
+
+	if (cache_time == 0) {
+		return;
+	}
+
+	key = talloc_asprintf_strupper_m(talloc_tos(), "USERNAME_MAP/%s",
+					 from);
+        if (key == NULL) {
+                return;
+        }
+	gencache_set(key, to, cache_time + time(NULL));
+	TALLOC_FREE(key);
+}
+
 bool map_username(struct smbd_server_connection *sconn, fstring user)
 {
 	XFILE *f;
@@ -97,6 +139,10 @@ bool map_username(struct smbd_server_connection *sconn, fstring user)
 		return true;
 	}
 
+	if (fetch_map_from_gencache(user)) {
+		return true;
+	}
+
 	/* first try the username map script */
 
 	if ( *cmd ) {
@@ -134,6 +180,7 @@ bool map_username(struct smbd_server_connection *sconn, fstring user)
 		if (numlines && qlines) {
 			DEBUG(3,("Mapped user %s to %s\n", user, qlines[0] ));
 			set_last_from_to(user, qlines[0]);
+			store_map_in_gencache(user, qlines[0]);
 			fstrcpy( user, qlines[0] );
 		}
 
@@ -197,6 +244,7 @@ bool map_username(struct smbd_server_connection *sconn, fstring user)
 			mapped_user = True;
 
 			set_last_from_to(user, unixname);
+			store_map_in_gencache(user, unixname);
 			fstrcpy( user, unixname );
 
 			if ( return_if_mapped ) {
@@ -217,6 +265,7 @@ bool map_username(struct smbd_server_connection *sconn, fstring user)
 	 */
 
 	set_last_from_to(user, user);
+	store_map_in_gencache(user, user);
 
 	return mapped_user;
 }