Merge branch 'tor-github/pr/1142'

changes/ticket30889

@@ -0,0 +1,3 @@
+  o Code simplification and refactoring:
+    - Eliminate some uses of lower-level control reply abstractions,
+      primarily in the onion_helper functions. Closes ticket 30889.

src/feature/control/control_auth.c

@@ -151,12 +151,8 @@ handle_control_authchallenge(control_connection_t *conn,
     goto fail;
   }
   if (args->kwargs == NULL || args->kwargs->next != NULL) {
-    /*    connection_write_str_to_buf("512 AUTHCHALLENGE requires exactly "
+    control_write_endreply(conn, 512,
-                                "2 arguments.\r\n", conn);
+                           "Wrong number of arguments for AUTHCHALLENGE");
-    */
-    control_printf_endreply(conn, 512,
-                            "AUTHCHALLENGE dislikes argument list %s",
-                            escaped(args->raw_body));
     goto fail;
   }
   if (strcmp(args->kwargs->key, "")) {

src/feature/control/control_cmd.c

@@ -703,9 +703,8 @@ handle_control_mapaddress(control_connection_t *conn,
     connection_buf_add(r, sz, TO_CONN(conn));
     tor_free(r);
   } else {
-    const char *response =
+    control_write_endreply(conn, 512, "syntax error: "
-      "512 syntax error: not enough arguments to mapaddress.\r\n";
+                           "not enough arguments to mapaddress.");
-    connection_buf_add(response, strlen(response), TO_CONN(conn));
   }
 
   SMARTLIST_FOREACH(reply, char *, cp, tor_free(cp));
@@ -845,7 +844,7 @@ handle_control_extendcircuit(control_connection_t *conn,
                "addresses that are allowed by the firewall configuration; "
                "circuit marked for closing.");
       circuit_mark_for_close(TO_CIRCUIT(circ), -END_CIRC_REASON_CONNECTFAILED);
-      connection_write_str_to_buf("551 Couldn't start circuit\r\n", conn);
+      control_write_endreply(conn, 551, "Couldn't start circuit");
       goto done;
     }
     circuit_append_new_exit(circ, info);
@@ -1744,16 +1743,10 @@ handle_control_add_onion(control_connection_t *conn,
         goto out;
 
     } else if (!strcasecmp(arg->key, "ClientAuth")) {
-      char *err_msg = NULL;
       int created = 0;
       rend_authorized_client_t *client =
-        add_onion_helper_clientauth(arg->value,
+        add_onion_helper_clientauth(arg->value, &created, conn);
-                                    &created, &err_msg);
       if (!client) {
-        if (err_msg) {
-          connection_write_str_to_buf(err_msg, conn);
-          tor_free(err_msg);
-        }
         goto out;
       }
 
@@ -1818,19 +1811,13 @@ handle_control_add_onion(control_connection_t *conn,
   add_onion_secret_key_t pk = { NULL };
   const char *key_new_alg = NULL;
   char *key_new_blob = NULL;
-  char *err_msg = NULL;
 
   const char *onionkey = smartlist_get(args->args, 0);
   if (add_onion_helper_keyarg(onionkey, discard_pk,
                               &key_new_alg, &key_new_blob, &pk, &hs_version,
-                              &err_msg) < 0) {
+                              conn) < 0) {
-    if (err_msg) {
-      connection_write_str_to_buf(err_msg, conn);
-      tor_free(err_msg);
-    }
     goto out;
   }
-  tor_assert(!err_msg);
 
   /* Hidden service version 3 don't have client authentication support so if
    * ClientAuth was given, send back an error. */
@@ -1876,7 +1863,7 @@ handle_control_add_onion(control_connection_t *conn,
         char *encoded = rend_auth_encode_cookie(ac->descriptor_cookie,
                                                 auth_type);
         tor_assert(encoded);
-        connection_printf_to_buf(conn, "250-ClientAuth=%s:%s\r\n",
+        control_printf_midreply(conn, 250, "ClientAuth=%s:%s",
                                 ac->client_name, encoded);
         memwipe(encoded, 0, strlen(encoded));
         tor_free(encoded);
@@ -1930,27 +1917,30 @@ handle_control_add_onion(control_connection_t *conn,
  * ADD_ONION command. Return a new crypto_pk_t and if a new key was generated
  * and the private key not discarded, the algorithm and serialized private key,
  * or NULL and an optional control protocol error message on failure.  The
- * caller is responsible for freeing the returned key_new_blob and err_msg.
+ * caller is responsible for freeing the returned key_new_blob.
  *
  * Note: The error messages returned are deliberately vague to avoid echoing
  * key material.
+ *
+ * Note: conn is only used for writing control replies. For testing
+ * purposes, it can be NULL if control_write_reply() is appropriately
+ * mocked.
  */
 STATIC int
 add_onion_helper_keyarg(const char *arg, int discard_pk,
                         const char **key_new_alg_out, char **key_new_blob_out,
                         add_onion_secret_key_t *decoded_key, int *hs_version,
-                        char **err_msg_out)
+                        control_connection_t *conn)
 {
   smartlist_t *key_args = smartlist_new();
   crypto_pk_t *pk = NULL;
   const char *key_new_alg = NULL;
   char *key_new_blob = NULL;
-  char *err_msg = NULL;
   int ret = -1;
 
   smartlist_split_string(key_args, arg, ":", SPLIT_IGNORE_BLANK, 0);
   if (smartlist_len(key_args) != 2) {
-    err_msg = tor_strdup("512 Invalid key type/blob\r\n");
+    control_write_endreply(conn, 512, "Invalid key type/blob");
     goto err;
   }
 
@@ -1967,12 +1957,12 @@ add_onion_helper_keyarg(const char *arg, int discard_pk,
     /* "RSA:<Base64 Blob>" - Loading a pre-existing RSA1024 key. */
     pk = crypto_pk_base64_decode_private(key_blob, strlen(key_blob));
     if (!pk) {
-      err_msg = tor_strdup("512 Failed to decode RSA key\r\n");
+      control_write_endreply(conn, 512, "Failed to decode RSA key");
       goto err;
     }
     if (crypto_pk_num_bits(pk) != PK_BYTES*8) {
       crypto_pk_free(pk);
-      err_msg = tor_strdup("512 Invalid RSA key size\r\n");
+      control_write_endreply(conn, 512, "Invalid RSA key size");
       goto err;
     }
     decoded_key->v2 = pk;
@@ -1983,7 +1973,7 @@ add_onion_helper_keyarg(const char *arg, int discard_pk,
     if (base64_decode((char *) sk->seckey, sizeof(sk->seckey), key_blob,
                       strlen(key_blob)) != sizeof(sk->seckey)) {
       tor_free(sk);
-      err_msg = tor_strdup("512 Failed to decode ED25519-V3 key\r\n");
+      control_write_endreply(conn, 512, "Failed to decode ED25519-V3 key");
       goto err;
     }
     decoded_key->v3 = sk;
@@ -1995,14 +1985,14 @@ add_onion_helper_keyarg(const char *arg, int discard_pk,
       /* "RSA1024", RSA 1024 bit, also currently "BEST" by default. */
       pk = crypto_pk_new();
       if (crypto_pk_generate_key(pk)) {
-        tor_asprintf(&err_msg, "551 Failed to generate %s key\r\n",
+        control_printf_endreply(conn, 551, "Failed to generate %s key",
                                 key_type_rsa1024);
         goto err;
       }
       if (!discard_pk) {
         if (crypto_pk_base64_encode_private(pk, &key_new_blob)) {
           crypto_pk_free(pk);
-          tor_asprintf(&err_msg, "551 Failed to encode %s key\r\n",
+          control_printf_endreply(conn, 551, "Failed to encode %s key",
                                   key_type_rsa1024);
           goto err;
         }
@@ -2014,7 +2004,7 @@ add_onion_helper_keyarg(const char *arg, int discard_pk,
       ed25519_secret_key_t *sk = tor_malloc_zero(sizeof(*sk));
       if (ed25519_secret_key_generate(sk, 1) < 0) {
         tor_free(sk);
-        tor_asprintf(&err_msg, "551 Failed to generate %s key\r\n",
+        control_printf_endreply(conn, 551, "Failed to generate %s key",
                                 key_type_ed25519_v3);
         goto err;
       }
@@ -2025,7 +2015,7 @@ add_onion_helper_keyarg(const char *arg, int discard_pk,
                           sizeof(sk->seckey), 0) != (len - 1)) {
           tor_free(sk);
           tor_free(key_new_blob);
-          tor_asprintf(&err_msg, "551 Failed to encode %s key\r\n",
+          control_printf_endreply(conn, 551, "Failed to encode %s key",
                                   key_type_ed25519_v3);
           goto err;
         }
@@ -2034,11 +2024,11 @@ add_onion_helper_keyarg(const char *arg, int discard_pk,
       decoded_key->v3 = sk;
       *hs_version = HS_VERSION_THREE;
     } else {
-      err_msg = tor_strdup("513 Invalid key type\r\n");
+      control_write_endreply(conn, 513, "Invalid key type");
       goto err;
     }
   } else {
-    err_msg = tor_strdup("513 Invalid key type\r\n");
+    control_write_endreply(conn, 513, "Invalid key type");
     goto err;
   }
 
@@ -2052,11 +2042,6 @@ add_onion_helper_keyarg(const char *arg, int discard_pk,
   });
   smartlist_free(key_args);
 
-  if (err_msg_out) {
-    *err_msg_out = err_msg;
-  } else {
-    tor_free(err_msg);
-  }
   *key_new_alg_out = key_new_alg;
   *key_new_blob_out = key_new_blob;
 
@@ -2066,27 +2051,30 @@ add_onion_helper_keyarg(const char *arg, int discard_pk,
 /** Helper function to handle parsing a ClientAuth argument to the
  * ADD_ONION command.  Return a new rend_authorized_client_t, or NULL
  * and an optional control protocol error message on failure.  The
- * caller is responsible for freeing the returned auth_client and err_msg.
+ * caller is responsible for freeing the returned auth_client.
  *
  * If 'created' is specified, it will be set to 1 when a new cookie has
  * been generated.
+ *
+ * Note: conn is only used for writing control replies. For testing
+ * purposes, it can be NULL if control_write_reply() is appropriately
+ * mocked.
  */
 STATIC rend_authorized_client_t *
-add_onion_helper_clientauth(const char *arg, int *created, char **err_msg)
+add_onion_helper_clientauth(const char *arg, int *created,
+                            control_connection_t *conn)
 {
   int ok = 0;
 
   tor_assert(arg);
   tor_assert(created);
-  tor_assert(err_msg);
-  *err_msg = NULL;
 
   smartlist_t *auth_args = smartlist_new();
   rend_authorized_client_t *client =
     tor_malloc_zero(sizeof(rend_authorized_client_t));
   smartlist_split_string(auth_args, arg, ":", 0, 0);
   if (smartlist_len(auth_args) < 1 || smartlist_len(auth_args) > 2) {
-    *err_msg = tor_strdup("512 Invalid ClientAuth syntax\r\n");
+    control_write_endreply(conn, 512, "Invalid ClientAuth syntax");
     goto err;
   }
   client->client_name = tor_strdup(smartlist_get(auth_args, 0));
@@ -2096,7 +2084,7 @@ add_onion_helper_clientauth(const char *arg, int *created, char **err_msg)
                                 client->descriptor_cookie,
                                 NULL, &decode_err_msg) < 0) {
       tor_assert(decode_err_msg);
-      tor_asprintf(err_msg, "512 %s\r\n", decode_err_msg);
+      control_write_endreply(conn, 512, decode_err_msg);
       tor_free(decode_err_msg);
       goto err;
     }
@@ -2107,7 +2095,7 @@ add_onion_helper_clientauth(const char *arg, int *created, char **err_msg)
   }
 
   if (!rend_valid_client_name(client->client_name)) {
-    *err_msg = tor_strdup("512 Invalid name in ClientAuth\r\n");
+    control_write_endreply(conn, 512, "Invalid name in ClientAuth");
     goto err;
   }
 

src/feature/control/control_cmd.h

@@ -91,10 +91,11 @@ STATIC int add_onion_helper_keyarg(const char *arg, int discard_pk,
                                    const char **key_new_alg_out,
                                    char **key_new_blob_out,
                                    add_onion_secret_key_t *decoded_key,
-                                   int *hs_version, char **err_msg_out);
+                                   int *hs_version,
+                                   control_connection_t *conn);
 
 STATIC rend_authorized_client_t *add_onion_helper_clientauth(const char *arg,
-                                   int *created, char **err_msg_out);
+                                   int *created, control_connection_t *conn);
 
 STATIC control_cmd_args_t *control_cmd_parse_args(
                                    const char *command,

src/feature/control/control_proto.c

@@ -176,8 +176,9 @@ send_control_done(control_connection_t *conn)
  * @param c separator character, usually ' ', '-', or '+'
  * @param s string
  */
-void
+MOCK_IMPL(void,
-control_write_reply(control_connection_t *conn, int code, int c, const char *s)
+control_write_reply, (control_connection_t *conn, int code, int c,
+                      const char *s))
 {
   connection_printf_to_buf(conn, "%03d%c%s\r\n", code, c, s);
 }

src/feature/control/control_proto.h

@@ -21,8 +21,8 @@ size_t write_escaped_data(const char *data, size_t len, char **out);
 size_t read_escaped_data(const char *data, size_t len, char **out);
 void send_control_done(control_connection_t *conn);
 
-void control_write_reply(control_connection_t *conn, int code, int c,
+MOCK_DECL(void, control_write_reply, (control_connection_t *conn, int code,
-                         const char *s);
+                                      int c, const char *s));
 void control_vprintf_reply(control_connection_t *conn, int code, int c,
                            const char *fmt, va_list ap)
   CHECK_PRINTF(4, 0);

src/test/test_controller.c

@@ -9,6 +9,7 @@
 #include "feature/control/control.h"
 #include "feature/control/control_cmd.h"
 #include "feature/control/control_getinfo.h"
+#include "feature/control/control_proto.h"
 #include "feature/client/entrynodes.h"
 #include "feature/hs/hs_common.h"
 #include "feature/nodelist/networkstatus.h"
@@ -201,42 +202,58 @@ static const control_cmd_syntax_t one_arg_kwargs_syntax = {
 static const parse_test_params_t parse_one_arg_kwargs_params =
   TESTPARAMS( one_arg_kwargs_syntax, one_arg_kwargs_tests );
 
+static char *reply_str = NULL;
+/* Mock for control_write_reply that copies the string for inspection
+ * by tests */
+static void
+mock_control_write_reply(control_connection_t *conn, int code, int c,
+                                const char *s)
+{
+  (void)conn;
+  (void)code;
+  (void)c;
+  tor_free(reply_str);
+  reply_str = tor_strdup(s);
+}
+
 static void
 test_add_onion_helper_keyarg_v3(void *arg)
 {
   int ret, hs_version;
   add_onion_secret_key_t pk;
   char *key_new_blob = NULL;
-  char *err_msg = NULL;
   const char *key_new_alg = NULL;
 
   (void) arg;
+  MOCK(control_write_reply, mock_control_write_reply);
 
   memset(&pk, 0, sizeof(pk));
 
   /* Test explicit ED25519-V3 key generation. */
+  tor_free(reply_str);
   ret = add_onion_helper_keyarg("NEW:ED25519-V3", 0, &key_new_alg,
                                 &key_new_blob, &pk, &hs_version,
-                                &err_msg);
+                                NULL);
   tt_int_op(ret, OP_EQ, 0);
   tt_int_op(hs_version, OP_EQ, HS_VERSION_THREE);
   tt_assert(pk.v3);
   tt_str_op(key_new_alg, OP_EQ, "ED25519-V3");
   tt_assert(key_new_blob);
-  tt_ptr_op(err_msg, OP_EQ, NULL);
+  tt_ptr_op(reply_str, OP_EQ, NULL);
   tor_free(pk.v3); pk.v3 = NULL;
   tor_free(key_new_blob);
 
   /* Test discarding the private key. */
+  tor_free(reply_str);
   ret = add_onion_helper_keyarg("NEW:ED25519-V3", 1, &key_new_alg,
                                 &key_new_blob, &pk, &hs_version,
-                                &err_msg);
+                                NULL);
   tt_int_op(ret, OP_EQ, 0);
   tt_int_op(hs_version, OP_EQ, HS_VERSION_THREE);
   tt_assert(pk.v3);
   tt_ptr_op(key_new_alg, OP_EQ, NULL);
   tt_ptr_op(key_new_blob, OP_EQ, NULL);
-  tt_ptr_op(err_msg, OP_EQ, NULL);
+  tt_ptr_op(reply_str, OP_EQ, NULL);
   tor_free(pk.v3); pk.v3 = NULL;
   tor_free(key_new_blob);
 
@@ -256,9 +273,10 @@ test_add_onion_helper_keyarg_v3(void *arg)
 
     tor_asprintf(&key_blob, "ED25519-V3:%s", base64_sk);
     tt_assert(key_blob);
+    tor_free(reply_str);
     ret = add_onion_helper_keyarg(key_blob, 1, &key_new_alg,
                                   &key_new_blob, &pk, &hs_version,
-                                  &err_msg);
+                                  NULL);
     tor_free(key_blob);
     tt_int_op(ret, OP_EQ, 0);
     tt_int_op(hs_version, OP_EQ, HS_VERSION_THREE);
@@ -266,7 +284,7 @@ test_add_onion_helper_keyarg_v3(void *arg)
     tt_mem_op(pk.v3, OP_EQ, hex_sk, 64);
     tt_ptr_op(key_new_alg, OP_EQ, NULL);
     tt_ptr_op(key_new_blob, OP_EQ, NULL);
-    tt_ptr_op(err_msg, OP_EQ, NULL);
+    tt_ptr_op(reply_str, OP_EQ, NULL);
     tor_free(pk.v3); pk.v3 = NULL;
     tor_free(key_new_blob);
   }
@@ -274,7 +292,8 @@ test_add_onion_helper_keyarg_v3(void *arg)
  done:
   tor_free(pk.v3);
   tor_free(key_new_blob);
-  tor_free(err_msg);
+  tor_free(reply_str);
+  UNMOCK(control_write_reply);
 }
 
 static void
@@ -285,72 +304,73 @@ test_add_onion_helper_keyarg_v2(void *arg)
   crypto_pk_t *pk1 = NULL;
   const char *key_new_alg = NULL;
   char *key_new_blob = NULL;
-  char *err_msg = NULL;
   char *encoded = NULL;
   char *arg_str = NULL;
 
   (void) arg;
+  MOCK(control_write_reply, mock_control_write_reply);
 
   memset(&pk, 0, sizeof(pk));
 
   /* Test explicit RSA1024 key generation. */
+  tor_free(reply_str);
   ret = add_onion_helper_keyarg("NEW:RSA1024", 0, &key_new_alg, &key_new_blob,
-                                &pk, &hs_version, &err_msg);
+                                &pk, &hs_version, NULL);
   tt_int_op(ret, OP_EQ, 0);
   tt_int_op(hs_version, OP_EQ, HS_VERSION_TWO);
   tt_assert(pk.v2);
   tt_str_op(key_new_alg, OP_EQ, "RSA1024");
   tt_assert(key_new_blob);
-  tt_ptr_op(err_msg, OP_EQ, NULL);
+  tt_ptr_op(reply_str, OP_EQ, NULL);
 
   /* Test "BEST" key generation (Assumes BEST = RSA1024). */
   crypto_pk_free(pk.v2); pk.v2 = NULL;
   tor_free(key_new_blob);
   ret = add_onion_helper_keyarg("NEW:BEST", 0, &key_new_alg, &key_new_blob,
-                                &pk, &hs_version, &err_msg);
+                                &pk, &hs_version, NULL);
   tt_int_op(ret, OP_EQ, 0);
   tt_int_op(hs_version, OP_EQ, HS_VERSION_TWO);
   tt_assert(pk.v2);
   tt_str_op(key_new_alg, OP_EQ, "RSA1024");
   tt_assert(key_new_blob);
-  tt_ptr_op(err_msg, OP_EQ, NULL);
+  tt_ptr_op(reply_str, OP_EQ, NULL);
 
   /* Test discarding the private key. */
   crypto_pk_free(pk.v2); pk.v2 = NULL;
   tor_free(key_new_blob);
   ret = add_onion_helper_keyarg("NEW:BEST", 1, &key_new_alg, &key_new_blob,
-                               &pk, &hs_version, &err_msg);
+                               &pk, &hs_version, NULL);
   tt_int_op(ret, OP_EQ, 0);
   tt_int_op(hs_version, OP_EQ, HS_VERSION_TWO);
   tt_assert(pk.v2);
   tt_ptr_op(key_new_alg, OP_EQ, NULL);
   tt_ptr_op(key_new_blob, OP_EQ, NULL);
-  tt_ptr_op(err_msg, OP_EQ, NULL);
+  tt_ptr_op(reply_str, OP_EQ, NULL);
 
   /* Test generating a invalid key type. */
   crypto_pk_free(pk.v2); pk.v2 = NULL;
   ret = add_onion_helper_keyarg("NEW:RSA512", 0, &key_new_alg, &key_new_blob,
-                               &pk, &hs_version, &err_msg);
+                               &pk, &hs_version, NULL);
   tt_int_op(ret, OP_EQ, -1);
   tt_int_op(hs_version, OP_EQ, HS_VERSION_TWO);
   tt_assert(!pk.v2);
   tt_ptr_op(key_new_alg, OP_EQ, NULL);
   tt_ptr_op(key_new_blob, OP_EQ, NULL);
-  tt_assert(err_msg);
+  tt_assert(reply_str);
 
   /* Test loading a RSA1024 key. */
-  tor_free(err_msg);
+  tor_free(reply_str);
   pk1 = pk_generate(0);
   tt_int_op(0, OP_EQ, crypto_pk_base64_encode_private(pk1, &encoded));
   tor_asprintf(&arg_str, "RSA1024:%s", encoded);
   ret = add_onion_helper_keyarg(arg_str, 0, &key_new_alg, &key_new_blob,
-                                &pk, &hs_version, &err_msg);
+                                &pk, &hs_version, NULL);
   tt_int_op(ret, OP_EQ, 0);
   tt_int_op(hs_version, OP_EQ, HS_VERSION_TWO);
   tt_assert(pk.v2);
   tt_ptr_op(key_new_alg, OP_EQ, NULL);
   tt_ptr_op(key_new_blob, OP_EQ, NULL);
-  tt_ptr_op(err_msg, OP_EQ, NULL);
+  tt_ptr_op(reply_str, OP_EQ, NULL);
   tt_int_op(crypto_pk_cmp_keys(pk1, pk.v2), OP_EQ, 0);
 
   /* Test loading a invalid key type. */
@@ -359,36 +379,37 @@ test_add_onion_helper_keyarg_v2(void *arg)
   crypto_pk_free(pk.v2); pk.v2 = NULL;
   tor_asprintf(&arg_str, "RSA512:%s", encoded);
   ret = add_onion_helper_keyarg(arg_str, 0, &key_new_alg, &key_new_blob,
-                                &pk, &hs_version, &err_msg);
+                                &pk, &hs_version, NULL);
   tt_int_op(ret, OP_EQ, -1);
   tt_int_op(hs_version, OP_EQ, HS_VERSION_TWO);
   tt_assert(!pk.v2);
   tt_ptr_op(key_new_alg, OP_EQ, NULL);
   tt_ptr_op(key_new_blob, OP_EQ, NULL);
-  tt_assert(err_msg);
+  tt_assert(reply_str);
 
   /* Test loading a invalid key. */
   tor_free(arg_str);
   crypto_pk_free(pk.v2); pk.v2 = NULL;
-  tor_free(err_msg);
+  tor_free(reply_str);
   encoded[strlen(encoded)/2] = '\0';
   tor_asprintf(&arg_str, "RSA1024:%s", encoded);
   ret = add_onion_helper_keyarg(arg_str, 0, &key_new_alg, &key_new_blob,
-                               &pk, &hs_version, &err_msg);
+                               &pk, &hs_version, NULL);
   tt_int_op(ret, OP_EQ, -1);
   tt_int_op(hs_version, OP_EQ, HS_VERSION_TWO);
   tt_assert(!pk.v2);
   tt_ptr_op(key_new_alg, OP_EQ, NULL);
   tt_ptr_op(key_new_blob, OP_EQ, NULL);
-  tt_assert(err_msg);
+  tt_assert(reply_str);
 
  done:
   crypto_pk_free(pk1);
   crypto_pk_free(pk.v2);
   tor_free(key_new_blob);
-  tor_free(err_msg);
+  tor_free(reply_str);
   tor_free(encoded);
   tor_free(arg_str);
+  UNMOCK(control_write_reply);
 }
 
 static void
@@ -542,49 +563,52 @@ static void
 test_add_onion_helper_clientauth(void *arg)
 {
   rend_authorized_client_t *client = NULL;
-  char *err_msg = NULL;
   int created = 0;
 
   (void)arg;
 
+  MOCK(control_write_reply, mock_control_write_reply);
   /* Test "ClientName" only. */
-  client = add_onion_helper_clientauth("alice", &created, &err_msg);
+  tor_free(reply_str);
+  client = add_onion_helper_clientauth("alice", &created, NULL);
   tt_assert(client);
   tt_assert(created);
-  tt_ptr_op(err_msg, OP_EQ, NULL);
+  tt_ptr_op(reply_str, OP_EQ, NULL);
   rend_authorized_client_free(client);
 
   /* Test "ClientName:Blob" */
+  tor_free(reply_str);
   client = add_onion_helper_clientauth("alice:475hGBHPlq7Mc0cRZitK/B",
-                                       &created, &err_msg);
+                                       &created, NULL);
   tt_assert(client);
   tt_assert(!created);
-  tt_ptr_op(err_msg, OP_EQ, NULL);
+  tt_ptr_op(reply_str, OP_EQ, NULL);
   rend_authorized_client_free(client);
 
   /* Test invalid client names */
+  tor_free(reply_str);
   client = add_onion_helper_clientauth("no*asterisks*allowed", &created,
-                                       &err_msg);
+                                       NULL);
   tt_ptr_op(client, OP_EQ, NULL);
-  tt_assert(err_msg);
+  tt_assert(reply_str);
-  tor_free(err_msg);
 
   /* Test invalid auth cookie */
-  client = add_onion_helper_clientauth("alice:12345", &created, &err_msg);
+  tor_free(reply_str);
+  client = add_onion_helper_clientauth("alice:12345", &created, NULL);
   tt_ptr_op(client, OP_EQ, NULL);
-  tt_assert(err_msg);
+  tt_assert(reply_str);
-  tor_free(err_msg);
 
   /* Test invalid syntax */
+  tor_free(reply_str);
   client = add_onion_helper_clientauth(":475hGBHPlq7Mc0cRZitK/B", &created,
-                                       &err_msg);
+                                       NULL);
   tt_ptr_op(client, OP_EQ, NULL);
-  tt_assert(err_msg);
+  tt_assert(reply_str);
-  tor_free(err_msg);
 
  done:
   rend_authorized_client_free(client);
-  tor_free(err_msg);
+  tor_free(reply_str);
+  UNMOCK(control_write_reply);
 }
 
 /* Mocks and data/variables used for GETINFO download status tests */