[RFC PATCH 02/13] migration: Normalize tls arguments

[Fabiano Rosas]

The tls_creds, tls_authz and tls_hostname arguments are strings that
can be set by the user. They are allowed to be either a valid string,
an empty string or NULL. The values "" and NULL are effectively
treated the same by the code, but this is not entirely clear because
the handling is not uniform.

Make the 3 variables be handled the same and at the same place in
options.c. Note that this affects only the internal usage of the
variables.

(migrate_tls() had to be moved to be able to use migrate_tls_creds())

Signed-off-by: Fabiano Rosas <faro...@suse.de>
---
 migration/options.c | 81 ++++++++++++++++++++++++---------------------
 migration/tls.c     |  2 +-
 2 files changed, 44 insertions(+), 39 deletions(-)

diff --git a/migration/options.c b/migration/options.c
index cb8eec218f..7cd465ca94 100644
--- a/migration/options.c
+++ b/migration/options.c
@@ -379,13 +379,6 @@ bool migrate_rdma(void)
     return s->rdma_migration;
 }
 
-bool migrate_tls(void)
-{
-    MigrationState *s = migrate_get_current();
-
-    return s->parameters.tls_creds && *s->parameters.tls_creds;
-}
-
 typedef enum WriteTrackingSupport {
     WT_SUPPORT_UNKNOWN = 0,
     WT_SUPPORT_ABSENT,
@@ -814,21 +807,41 @@ const char *migrate_tls_authz(void)
 {
     MigrationState *s = migrate_get_current();
 
-    return s->parameters.tls_authz;
+    if (s->parameters.tls_authz &&
+        *s->parameters.tls_authz) {
+        return s->parameters.tls_authz;
+    }
+
+    return NULL;
 }
 
 const char *migrate_tls_creds(void)
 {
     MigrationState *s = migrate_get_current();
 
-    return s->parameters.tls_creds;
+    if (s->parameters.tls_creds &&
+        *s->parameters.tls_creds) {
+        return s->parameters.tls_creds;
+    }
+
+    return NULL;
 }
 
 const char *migrate_tls_hostname(void)
 {
     MigrationState *s = migrate_get_current();
 
-    return s->parameters.tls_hostname;
+    if (s->parameters.tls_hostname &&
+        *s->parameters.tls_hostname) {
+        return s->parameters.tls_hostname;
+    }
+
+    return NULL;
+}
+
+bool migrate_tls(void)
+{
+    return !!migrate_tls_creds();
 }
 
 uint64_t migrate_vcpu_dirty_limit_period(void)
@@ -883,8 +896,10 @@ MigrationParameters *qmp_query_migrate_parameters(Error 
**errp)
     params->cpu_throttle_increment = s->parameters.cpu_throttle_increment;
     params->has_cpu_throttle_tailslow = true;
     params->cpu_throttle_tailslow = s->parameters.cpu_throttle_tailslow;
-    params->tls_creds = g_strdup(s->parameters.tls_creds);
-    params->tls_hostname = g_strdup(s->parameters.tls_hostname);
+    params->tls_creds = g_strdup(s->parameters.tls_creds ?
+                                 s->parameters.tls_creds : "");
+    params->tls_hostname = g_strdup(s->parameters.tls_hostname ?
+                                    s->parameters.tls_hostname : "");
     params->tls_authz = g_strdup(s->parameters.tls_authz ?
                                  s->parameters.tls_authz : "");
     params->has_max_bandwidth = true;
@@ -945,6 +960,7 @@ void migrate_params_init(MigrationParameters *params)
 {
     params->tls_hostname = g_strdup("");
     params->tls_creds = g_strdup("");
+    params->tls_authz = g_strdup("");
 
     /* Set has_* up only for parameter checks */
     params->has_throttle_trigger_threshold = true;
@@ -1184,18 +1200,27 @@ static void 
migrate_params_test_apply(MigrateSetParameters *params,
     }
 
     if (params->tls_creds) {
-        assert(params->tls_creds->type == QTYPE_QSTRING);
-        dest->tls_creds = params->tls_creds->u.s;
+        if (params->tls_creds->type == QTYPE_QNULL) {
+            dest->tls_creds = NULL;
+        } else {
+            dest->tls_creds = params->tls_creds->u.s;
+        }
     }
 
     if (params->tls_hostname) {
-        assert(params->tls_hostname->type == QTYPE_QSTRING);
-        dest->tls_hostname = params->tls_hostname->u.s;
+        if (params->tls_hostname->type == QTYPE_QNULL) {
+            dest->tls_hostname = NULL;
+        } else {
+            dest->tls_hostname = params->tls_hostname->u.s;
+        }
     }
 
     if (params->tls_authz) {
-        assert(params->tls_authz->type == QTYPE_QSTRING);
-        dest->tls_authz = params->tls_authz->u.s;
+        if (params->tls_authz->type == QTYPE_QNULL) {
+            dest->tls_authz = NULL;
+        } else {
+            dest->tls_authz = params->tls_authz->u.s;
+        }
     }
 
     if (params->has_max_bandwidth) {
@@ -1413,26 +1438,6 @@ void qmp_migrate_set_parameters(MigrateSetParameters 
*params, Error **errp)
 {
     MigrationParameters tmp;
 
-    /* TODO Rewrite "" to null instead for all three tls_* parameters */
-    if (params->tls_creds
-        && params->tls_creds->type == QTYPE_QNULL) {
-        qobject_unref(params->tls_creds->u.n);
-        params->tls_creds->type = QTYPE_QSTRING;
-        params->tls_creds->u.s = strdup("");
-    }
-    if (params->tls_hostname
-        && params->tls_hostname->type == QTYPE_QNULL) {
-        qobject_unref(params->tls_hostname->u.n);
-        params->tls_hostname->type = QTYPE_QSTRING;
-        params->tls_hostname->u.s = strdup("");
-    }
-    if (params->tls_authz
-        && params->tls_authz->type == QTYPE_QNULL) {
-        qobject_unref(params->tls_authz->u.n);
-        params->tls_authz->type = QTYPE_QSTRING;
-        params->tls_authz->u.s = strdup("");
-    }
-
     migrate_params_test_apply(params, &tmp);
 
     if (!migrate_params_check(&tmp, errp)) {
diff --git a/migration/tls.c b/migration/tls.c
index 5cbf952383..8a89d3f767 100644
--- a/migration/tls.c
+++ b/migration/tls.c
@@ -126,7 +126,7 @@ QIOChannelTLS *migration_tls_client_create(QIOChannel *ioc,
     }
 
     const char *tls_hostname = migrate_tls_hostname();
-    if (tls_hostname && *tls_hostname) {
+    if (tls_hostname) {
         hostname = tls_hostname;
     }
 
-- 
2.35.3