autofs-5.1.6 - add support for new sss autofs proto version call

From: Ian Kent <raven@themaw.net>

Add sss protocol feature version function existence check and local get
function.

Signed-off-by: Ian Kent <raven@themaw.net>
---
 CHANGELOG            |    1 +
 modules/lookup_sss.c |   44 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 45 insertions(+)

diff --git a/CHANGELOG b/CHANGELOG
index 1830730..7c22aa1 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -96,6 +96,7 @@ xx/xx/2018 autofs-5.1.5
 - fix sss_master_map_wait timing.
 - add sss ECONREFUSED return handling.
 - use mapname in sss context for setautomntent().
+- add support for new sss autofs proto version call.
 
 19/12/2017 autofs-5.1.4
 - fix spec file url.
diff --git a/modules/lookup_sss.c b/modules/lookup_sss.c
index c44c55d..3819981 100644
--- a/modules/lookup_sss.c
+++ b/modules/lookup_sss.c
@@ -37,11 +37,29 @@
 
 #define SSS_SO_NAME "libsss_autofs"
 
+/* If the sss library protocol version is greater than 0 there are
+ * more possibile error returns from the sss autofs library calls.
+ *
+ * If ECONNREFUSED is returned then sssd is not running or not
+ * configured on the system, immediately return an unavailable
+ * status.
+ *
+ * A return of EHOSTDOWN means sss backend server is down so we
+ * should retry.
+ *
+ * With older sss ilibrary we can get a return of ENOENT for the
+ * above cases so also wait in that case since we can't be sure
+ * the map doesn't exist.
+ */
+#define SSS_PROTO_VERSION 1
+
+unsigned int _sss_auto_protocol_version(unsigned int);
 int _sss_setautomntent(const char *, void **);
 int _sss_getautomntent_r(char **, char **, void *);
 int _sss_getautomntbyname_r(char *, char **, void *);
 int _sss_endautomntent(void **);
 
+typedef unsigned int (*protocol_version_t) (unsigned int);
 typedef int (*setautomntent_t) (const char *, void **);
 typedef int (*getautomntent_t) (char **, char **, void *);
 typedef int (*getautomntbyname_t) (char *, char **, void *);
@@ -50,6 +68,7 @@ typedef int (*endautomntent_t) (void **);
 struct lookup_context {
 	const char *mapname;
     	void *dlhandle;
+	protocol_version_t protocol_version;
 	setautomntent_t setautomntent;
 	getautomntent_t getautomntent_r;
 	getautomntbyname_t getautomntbyname_r;
@@ -58,6 +77,8 @@ struct lookup_context {
 };
 
 int lookup_version = AUTOFS_LOOKUP_VERSION;	/* Required by protocol */
+int sss_proto_version = SSS_PROTO_VERSION;	/* 0 => initial version,
+						 * >= 1 => new error handling. */
 
 static int open_sss_lib(struct lookup_context *ctxt)
 {
@@ -78,6 +99,11 @@ static int open_sss_lib(struct lookup_context *ctxt)
 		return 1;
 	ctxt->dlhandle = dh;
 
+	/* Don't fail on NULL, it's simply not present in this version of the
+	 * sss autofs library.
+	 */
+	ctxt->protocol_version = (protocol_version_t) dlsym(dh, "_sss_auto_protocol_version");
+
 	ctxt->setautomntent = (setautomntent_t) dlsym(dh, "_sss_setautomntent");
 	if (!ctxt->setautomntent)
 		goto lib_names_fail;
@@ -193,6 +219,7 @@ int lookup_reinit(const char *mapfmt,
 	}
 
 	new->dlhandle = ctxt->dlhandle;
+	new->protocol_version = ctxt->protocol_version;
 	new->setautomntent = ctxt->setautomntent;
 	new->getautomntent_r = ctxt->getautomntent_r;
 	new->getautomntbyname_r = ctxt->getautomntbyname_r;
@@ -219,6 +246,23 @@ static int setautomntent(unsigned int logopt,
 	return ret;
 }
 
+static unsigned int proto_version(struct lookup_context *ctxt)
+{
+	unsigned int proto_version = 0;
+
+	if (ctxt->protocol_version) {
+		/* If ctxt->protocol_version() is defined it's assumed
+		 * that for sss_proto_version <= sss autofs library
+		 * protocol version ctxt->protocol_version() will
+		 * return the version requested by autofs to indicate
+		 * it userstands what the autofs module is capable of
+		 * handling.
+		 */
+		proto_version = ctxt->protocol_version(sss_proto_version);
+	}
+	return proto_version;
+}
+
 static int setautomntent_wait(unsigned int logopt,
 			      struct lookup_context *ctxt,
 			      void **sss_ctxt, unsigned int retries)