kadm5/kadmin: Add read-only mode

Now we can have read-only kadmind instances.

lib/kadm5/admin.h

@@ -204,6 +204,8 @@ typedef struct _kadm5_policy_ent_t {
 #define KADM5_CONFIG_EXPIRATION			(1 << 16)
 #define KADM5_CONFIG_FLAGS			(1 << 17)
 #define KADM5_CONFIG_ENCTYPES			(1 << 18)
+#define KADM5_CONFIG_READONLY_ADMIN_SERVER	(1 << 19)
+#define KADM5_CONFIG_READONLY_KADMIN_PORT	(1 << 20)
 
 #define KADM5_PRIV_GET		(1 << 0)
 #define KADM5_PRIV_ADD 		(1 << 1)
@@ -218,6 +220,10 @@ typedef struct _kadm5_policy_ent_t {
 
 #define KADM5_BOGUS_KEY_DATA    "\xe5\xe5\xe5\xe5"
 
+/*
+ * ABI NOTE: We can add fields at the end of this provided that we define new
+ * mask bits that must be set in the mask field when setting the new fields.
+ */
 typedef struct _kadm5_config_params {
     uint32_t mask;
 
@@ -234,6 +240,10 @@ typedef struct _kadm5_config_params {
 
     /* server library (database) fields */
     char *stash_file;
+
+    /* read-only kadmin server */
+    char *readonly_admin_server;
+    int readonly_kadmind_port;
 } kadm5_config_params;
 
 typedef krb5_error_code kadm5_ret_t;

lib/kadm5/chpass_c.c

@@ -58,7 +58,7 @@ kadm5_c_chpass_principal(void *server_handle,
     if (n_ks_tuple > 0)
        return KADM5_KS_TUPLE_NOSUPP;
 
-    ret = _kadm5_connect(server_handle);
+    ret = _kadm5_connect(server_handle, 1 /* want_write */);
     if (ret)
 	return ret;
 
@@ -121,7 +121,7 @@ kadm5_c_chpass_principal_with_key(void *server_handle,
     krb5_data reply;
     int i;
 
-    ret = _kadm5_connect(server_handle);
+    ret = _kadm5_connect(server_handle, 1 /* want_write */);
     if (ret)
 	return ret;
 

lib/kadm5/create_c.c

@@ -64,7 +64,7 @@ kadm5_c_create_principal(void *server_handle,
     if (n_ks_tuple > 0)
 	return KADM5_KS_TUPLE_NOSUPP;
 
-    ret = _kadm5_connect(server_handle);
+    ret = _kadm5_connect(server_handle, 1 /* want_write */);
     if (ret)
 	return ret;
 

lib/kadm5/delete_c.c

@@ -45,7 +45,7 @@ kadm5_c_delete_principal(void *server_handle, krb5_principal princ)
     int32_t tmp;
     krb5_data reply;
 
-    ret = _kadm5_connect(server_handle);
+    ret = _kadm5_connect(server_handle, 1 /* want_write */);
     if (ret)
 	return ret;
 

lib/kadm5/destroy_c.c

@@ -41,6 +41,7 @@ kadm5_c_destroy(void *server_handle)
     kadm5_client_context *context = server_handle;
 
     free(context->realm);
+    free(context->readonly_admin_server);
     free(context->admin_server);
     rk_closesocket(context->sock);
     if (context->client_name)

lib/kadm5/get_c.c

@@ -48,7 +48,7 @@ kadm5_c_get_principal(void *server_handle,
     int32_t tmp;
     krb5_data reply;
 
-    ret = _kadm5_connect(server_handle);
+    ret = _kadm5_connect(server_handle, 0 /* want_write */);
     if (ret)
 	return ret;
 

lib/kadm5/get_princs_c.c

@@ -52,7 +52,7 @@ kadm5_c_get_principals(void *server_handle,
     *count = 0;
     *princs = NULL;
 
-    ret = _kadm5_connect(server_handle);
+    ret = _kadm5_connect(server_handle, 0 /* want_write */);
     if (ret)
 	return ret;
 

lib/kadm5/init_c.c

@@ -89,13 +89,13 @@ _kadm5_c_init_context(kadm5_client_context **ctx,
     char *colon;
 
     *ctx = malloc(sizeof(**ctx));
-    if(*ctx == NULL)
+    if (*ctx == NULL)
 	return krb5_enomem(context);
     memset(*ctx, 0, sizeof(**ctx));
-    krb5_add_et_list (context, initialize_kadm5_error_table_r);
+    krb5_add_et_list(context, initialize_kadm5_error_table_r);
     set_funcs(*ctx);
     (*ctx)->context = context;
-    if(params->mask & KADM5_CONFIG_REALM) {
+    if (params->mask & KADM5_CONFIG_REALM) {
 	ret = 0;
 	(*ctx)->realm = strdup(params->realm);
 	if ((*ctx)->realm == NULL)
@@ -106,19 +106,24 @@ _kadm5_c_init_context(kadm5_client_context **ctx,
 	free(*ctx);
 	return ret;
     }
-    if(params->mask & KADM5_CONFIG_ADMIN_SERVER)
+
+    /*
+     * FIXME: If we have a hostlist, we should use the hostlist so that if we
+     *        can't reach one server we try another.
+     */
+    if (params->mask & KADM5_CONFIG_ADMIN_SERVER)
 	(*ctx)->admin_server = strdup(params->admin_server);
     else {
 	char **hostlist;
 
-	ret = krb5_get_krb_admin_hst (context, &(*ctx)->realm, &hostlist);
+	ret = krb5_get_krb_admin_hst(context, &(*ctx)->realm, &hostlist);
 	if (ret) {
 	    free((*ctx)->realm);
 	    free(*ctx);
 	    return ret;
 	}
 	(*ctx)->admin_server = strdup(*hostlist);
-	krb5_free_krbhst (context, hostlist);
+	krb5_free_krbhst(context, hostlist);
     }
 
     if ((*ctx)->admin_server == NULL) {
@@ -126,22 +131,64 @@ _kadm5_c_init_context(kadm5_client_context **ctx,
 	free(*ctx);
 	return krb5_enomem(context);
     }
-    colon = strchr ((*ctx)->admin_server, ':');
+    colon = strchr((*ctx)->admin_server, ':');
     if (colon != NULL)
 	*colon++ = '\0';
 
     (*ctx)->kadmind_port = 0;
 
-    if(params->mask & KADM5_CONFIG_KADMIND_PORT)
+    if (params->mask & KADM5_CONFIG_KADMIND_PORT)
 	(*ctx)->kadmind_port = params->kadmind_port;
     else if (colon != NULL) {
 	char *end;
 
-	(*ctx)->kadmind_port = htons(strtol (colon, &end, 0));
+	(*ctx)->kadmind_port = htons(strtol(colon, &end, 0));
     }
     if ((*ctx)->kadmind_port == 0)
-	(*ctx)->kadmind_port = krb5_getportbyname (context, "kerberos-adm",
-						   "tcp", 749);
+	(*ctx)->kadmind_port = krb5_getportbyname(context, "kerberos-adm",
+						  "tcp", 749);
+
+    if (params->mask & KADM5_CONFIG_READONLY_ADMIN_SERVER) {
+	(*ctx)->readonly_admin_server = strdup(params->readonly_admin_server);
+        if ((*ctx)->readonly_admin_server == NULL) {
+            free((*ctx)->realm);
+            free(*ctx);
+            return krb5_enomem(context);
+        }
+    } else {
+	char **hostlist;
+
+        ret = krb5_get_krb_readonly_admin_hst(context, &(*ctx)->realm,
+                                              &hostlist);
+        if (ret == 0) {
+            (*ctx)->readonly_admin_server = strdup(*hostlist);
+            krb5_free_krbhst(context, hostlist);
+            if ((*ctx)->readonly_admin_server == NULL) {
+                free((*ctx)->realm);
+                free(*ctx);
+                return krb5_enomem(context);
+            }
+        }
+    }
+    if ((*ctx)->readonly_admin_server) {
+        colon = strchr((*ctx)->readonly_admin_server, ':');
+        if (colon != NULL)
+            *colon++ = '\0';
+
+    } else {
+        colon = NULL;
+    }
+
+    (*ctx)->readonly_kadmind_port = 0;
+    if (params->mask & KADM5_CONFIG_READONLY_KADMIN_PORT)
+	(*ctx)->readonly_kadmind_port = params->readonly_kadmind_port;
+    else if (colon != NULL) {
+	char *end;
+
+	(*ctx)->readonly_kadmind_port = htons(strtol(colon, &end, 0));
+    }
+    if ((*ctx)->readonly_kadmind_port == 0)
+	(*ctx)->readonly_kadmind_port = (*ctx)->kadmind_port;
     return 0;
 }
 
@@ -434,10 +481,24 @@ kadm_connect(kadm5_client_context *ctx)
     struct addrinfo *ai, *a;
     struct addrinfo hints;
     int error;
+    int kadmin_port = 0;
+    const char *admin_server = NULL;
     char portstr[NI_MAXSERV];
     char *hostname, *slash;
     char *service_name;
     krb5_context context = ctx->context;
+    int writable = 0;
+
+    if (!ctx->want_write) {
+        admin_server = ctx->readonly_admin_server;
+        kadmin_port = ctx->readonly_kadmind_port;
+    }
+    if (admin_server == NULL) {
+        admin_server = ctx->admin_server;
+        writable = 1;
+    }
+    if (kadmin_port < 1)
+        kadmin_port = ctx->kadmind_port;
 
     memset (&hints, 0, sizeof(hints));
     hints.ai_socktype = SOCK_STREAM;
@@ -563,14 +624,31 @@ kadm_connect(kadm5_client_context *ctx)
 	krb5_cc_close(context, cc);
     ctx->sock = s;
 
+    ctx->connected_to_writable = !!writable;
     return 0;
 }
 
 kadm5_ret_t
-_kadm5_connect(void *handle)
+_kadm5_connect(void *handle, int want_write)
 {
     kadm5_client_context *ctx = handle;
-    if(ctx->sock == -1)
+
+    /*
+     * Reconnect?  Note that we don't reconnect to read-only kadmin servers if
+     * we're already connected to a writable kadmin server because we sometimes
+     * get a principal record after writing it.  We really need the application
+     * upstairs to tell us when to stop hogging writable kadmin servers.
+     *
+     * FIXME: Add an API for marking a kadm5_client_context as not needing to
+     * connect to writable kadmin servers.
+     */
+    ctx->want_write = !!want_write;
+    if (ctx->sock != rk_INVALID_SOCKET && want_write &&
+        !ctx->connected_to_writable) {
+        rk_closesocket(ctx->sock);
+        ctx->sock = rk_INVALID_SOCKET;
+    }
+    if (ctx->sock == rk_INVALID_SOCKET)
 	return kadm_connect(ctx);
     return 0;
 }

lib/kadm5/kadm5_err.et

@@ -71,3 +71,4 @@ error_code BAD_SERVER_HOOK,	    "Bad KADM5 server hook"
 error_code SERVER_HOOK_NOT_FOUND,   "Cannot find KADM5 server hook"
 error_code OLD_SERVER_HOOK_VERSION, "KADM5 server hook is too old for this version of Heimdal"
 error_code NEW_SERVER_HOOK_VERSION, "KADM5 server hook is too new for this version of Heimdal"
+error_code READ_ONLY,           "Database is read-only; try primary server"

lib/kadm5/modify_c.c

@@ -47,7 +47,7 @@ kadm5_c_modify_principal(void *server_handle,
     int32_t tmp;
     krb5_data reply;
 
-    ret = _kadm5_connect(server_handle);
+    ret = _kadm5_connect(server_handle, 1 /* want_write */);
     if (ret)
 	return ret;
 

lib/kadm5/private.h

@@ -137,6 +137,10 @@ typedef struct kadm5_client_context {
     const char *keytab;
     krb5_ccache ccache;
     kadm5_config_params *realm_params;
+    char *readonly_admin_server;
+    int readonly_kadmind_port;
+    unsigned int want_write:1;
+    unsigned int connected_to_writable:1;
 } kadm5_client_context;
 
 typedef struct kadm5_ad_context {

lib/kadm5/privs_c.c

@@ -47,7 +47,7 @@ kadm5_c_get_privs(void *server_handle, uint32_t *privs)
 
     *privs = 0;
 
-    ret = _kadm5_connect(server_handle);
+    ret = _kadm5_connect(server_handle, 0 /* want_write */);
     if (ret)
 	return ret;
 

lib/kadm5/prune_c.c

@@ -44,7 +44,7 @@ kadm5_c_prune_principal(void *server_handle, krb5_principal princ, int kvno)
     krb5_data reply;
 
     krb5_data_zero(&reply);
-    ret = _kadm5_connect(server_handle);
+    ret = _kadm5_connect(server_handle, 1 /* want_write */);
     if (ret == 0 && (sp = krb5_storage_from_mem(buf, sizeof(buf))) == NULL)
         ret = krb5_enomem(context->context);
     if (ret == 0)

lib/kadm5/randkey_c.c

@@ -53,7 +53,7 @@ kadm5_c_randkey_principal(void *server_handle,
     krb5_data reply;
     krb5_keyblock *k;
 
-    ret = _kadm5_connect(server_handle);
+    ret = _kadm5_connect(server_handle, 1 /* want_write */);
     if (ret)
 	return ret;
 

lib/kadm5/rename_c.c

@@ -47,7 +47,7 @@ kadm5_c_rename_principal(void *server_handle,
     int32_t tmp;
     krb5_data reply;
 
-    ret = _kadm5_connect(server_handle);
+    ret = _kadm5_connect(server_handle, 1 /* want_write */);
     if (ret)
 	return ret;