Merge branch 'ticket31240v2' into ticket31240v2_merged_2

1 files changed, 589 insertions, 157 deletions

diff --git a/src/app/config/confparse.c b/src/app/config/confparse.c
index 6e2624466a..f20a361ba3 100644
--- a/src/app/config/confparse.c
+++ b/src/app/config/confparse.c
@@ -37,16 +37,349 @@
 #include "lib/string/printf.h"
 #include "lib/string/util_string.h"
 
-static void config_reset(const config_format_t *fmt, void *options,
-                         const config_var_t *var, int use_defaults);
+#include "ext/siphash.h"
+
+/**
+ * A managed_var_t is an internal wrapper around a config_var_t in
+ * a config_format_t structure.  It is used by config_mgr_t to
+ * keep track of which option goes with which structure. */
+typedef struct managed_var_t {
+  /**
+   * A pointer to the config_var_t for this option.
+   */
+  const config_var_t *cvar;
+  /**
+   * The index of the object in which this option is stored.  It is
+   * IDX_TOPLEVEL to indicate that the object is the top-level object.
+   **/
+  int object_idx;
+} managed_var_t;
+
+static void config_reset(const config_mgr_t *fmt, void *options,
+                         const managed_var_t *var, int use_defaults);
+static void config_mgr_register_fmt(config_mgr_t *mgr,
+                                    const config_format_t *fmt,
+                                    int object_idx);
+
+/** Release all storage held in a managed_var_t. */
+static void
+managed_var_free_(managed_var_t *mv)
+{
+  if (!mv)
+    return;
+  tor_free(mv);
+}
+#define managed_var_free(mv) \
+  FREE_AND_NULL(managed_var_t, managed_var_free_, (mv))
+
+struct config_suite_t {
+  /** A list of configuration objects managed by a given configuration
+   * manager. They are stored in the same order as the config_format_t
+   * objects in the manager's list of subformats. */
+  smartlist_t *configs;
+};
+
+/**
+ * Allocate a new empty config_suite_t.
+ **/
+static config_suite_t *
+config_suite_new(void)
+{
+  config_suite_t *suite = tor_malloc_zero(sizeof(config_suite_t));
+  suite->configs = smartlist_new();
+  return suite;
+}
+
+/** Release all storage held by a config_suite_t.  (Does not free
+ * any configuration objects it holds; the caller must do that first.) */
+static void
+config_suite_free_(config_suite_t *suite)
+{
+  if (!suite)
+    return;
+  smartlist_free(suite->configs);
+  tor_free(suite);
+}
+
+#define config_suite_free(suite) \
+  FREE_AND_NULL(config_suite_t, config_suite_free_, (suite))
+
+struct config_mgr_t {
+  /** The 'top-level' configuration format.  This one is used for legacy
+   * options that have not yet been assigned to different sub-modules.
+   *
+   * (NOTE: for now, this is the only config_format_t that a config_mgr_t
+   * contains.  A subsequent commit will add more. XXXX)
+   */
+  const config_format_t *toplevel;
+  /**
+   * List of second-level configuration format objects that this manager
+   * also knows about.
+   */
+  smartlist_t *subconfigs;
+  /** A smartlist of managed_var_t objects for all configuration formats. */
+  smartlist_t *all_vars;
+  /** A smartlist of config_abbrev_t objects for all configuration
+   * formats. These objects are used to track synonyms and abbreviations for
+   * different configuration options. */
+  smartlist_t *all_abbrevs;
+  /** A smartlist of config_deprecation_t for all configuration formats. */
+  smartlist_t *all_deprecations;
+  /** True if this manager has been frozen and cannot have any more formats
+   * added to it. A manager must be frozen before it can be used to construct
+   * or manipulate objects. */
+  bool frozen;
+  /** A replacement for the magic number of the toplevel object. We override
+   * that number to make it unique for this particular config_mgr_t, so that
+   * an object constructed with one mgr can't be used with another, even if
+   * those managers' contents are equal.
+   */
+  struct_magic_decl_t toplevel_magic;
+};
+
+#define IDX_TOPLEVEL (-1)
+
+/** Create a new config_mgr_t to manage a set of configuration objects to be
+ * wrapped under <b>toplevel_fmt</b>. */
+config_mgr_t *
+config_mgr_new(const config_format_t *toplevel_fmt)
+{
+  config_mgr_t *mgr = tor_malloc_zero(sizeof(config_mgr_t));
+  mgr->subconfigs = smartlist_new();
+  mgr->all_vars = smartlist_new();
+  mgr->all_abbrevs = smartlist_new();
+  mgr->all_deprecations = smartlist_new();
+
+  config_mgr_register_fmt(mgr, toplevel_fmt, IDX_TOPLEVEL);
+  mgr->toplevel = toplevel_fmt;
+
+  return mgr;
+}
+
+/** Add a config_format_t to a manager, with a specified (unique) index. */
+static void
+config_mgr_register_fmt(config_mgr_t *mgr,
+                        const config_format_t *fmt,
+                        int object_idx)
+{
+  int i;
+
+  tor_assertf(!mgr->frozen,
+              "Tried to add a format to a configuration manager after "
+              "it had been frozen.");
+
+  if (object_idx != IDX_TOPLEVEL) {
+    tor_assertf(fmt->config_suite_offset < 0,
+          "Tried to register a toplevel format in a non-toplevel position");
+  }
+  tor_assertf(fmt != mgr->toplevel &&
+              ! smartlist_contains(mgr->subconfigs, fmt),
+              "Tried to register an already-registered format.");
+
+  /* register variables */
+  for (i = 0; fmt->vars[i].member.name; ++i) {
+    managed_var_t *mv = tor_malloc_zero(sizeof(managed_var_t));
+    mv->cvar = &fmt->vars[i];
+    mv->object_idx = object_idx;
+    smartlist_add(mgr->all_vars, mv);
+  }
+
+  /* register abbrevs */
+  if (fmt->abbrevs) {
+    for (i = 0; fmt->abbrevs[i].abbreviated; ++i) {
+      smartlist_add(mgr->all_abbrevs, (void*)&fmt->abbrevs[i]);
+    }
+  }
+
+  /* register deprecations. */
+  if (fmt->deprecations) {
+    const config_deprecation_t *d;
+    for (d = fmt->deprecations; d->name; ++d) {
+      smartlist_add(mgr->all_deprecations, (void*)d);
+    }
+  }
+}
+
+/**
+ * Add a new format to this configuration object.  Asserts on failure.
+ *
+ **/
+int
+config_mgr_add_format(config_mgr_t *mgr,
+                      const config_format_t *fmt)
+{
+  tor_assert(mgr);
+  int idx = smartlist_len(mgr->subconfigs);
+  config_mgr_register_fmt(mgr, fmt, idx);
+  smartlist_add(mgr->subconfigs, (void *)fmt);
+  return idx;
+}
+
+/** Return a pointer to the config_suite_t * pointer inside a
+ * configuration object; returns NULL if there is no such member. */
+static inline config_suite_t **
+config_mgr_get_suite_ptr(const config_mgr_t *mgr, void *toplevel)
+{
+  if (mgr->toplevel->config_suite_offset < 0)
+    return NULL;
+  return STRUCT_VAR_P(toplevel, mgr->toplevel->config_suite_offset);
+}
+
+/**
+ * Return a pointer to the configuration object within <b>toplevel</b> whose
+ * index is <b>idx</b>.
+ *
+ * NOTE: XXXX Eventually, there will be multiple objects supported within the
+ * toplevel object.  For example, the or_options_t will contain pointers
+ * to configuration objects for other modules.  This function gets
+ * the sub-object for a particular module.
+ */
+STATIC void *
+config_mgr_get_obj_mutable(const config_mgr_t *mgr, void *toplevel, int idx)
+{
+  tor_assert(mgr);
+  tor_assert(toplevel);
+  if (idx == IDX_TOPLEVEL)
+    return toplevel;
+
+  tor_assertf(idx >= 0 && idx < smartlist_len(mgr->subconfigs),
+              "Index %d is out of range.", idx);
+  config_suite_t **suite = config_mgr_get_suite_ptr(mgr, toplevel);
+  tor_assert(suite);
+  tor_assert(smartlist_len(mgr->subconfigs) ==
+             smartlist_len((*suite)->configs));
+
+  return smartlist_get((*suite)->configs, idx);
+}
+
+/** As config_mgr_get_obj_mutable(), but return a const pointer. */
+STATIC const void *
+config_mgr_get_obj(const config_mgr_t *mgr, const void *toplevel, int idx)
+{
+  return config_mgr_get_obj_mutable(mgr, (void*)toplevel, idx);
+}
+
+/** Sorting helper for smartlist of managed_var_t */
+static int
+managed_var_cmp(const void **a, const void **b)
+{
+  const managed_var_t *mv1 = *(const managed_var_t**)a;
+  const managed_var_t *mv2 = *(const managed_var_t**)b;
+
+  return strcasecmp(mv1->cvar->member.name, mv2->cvar->member.name);
+}
+
+/**
+ * Mark a configuration manager as "frozen", so that no more formats can be
+ * added, and so that it can be used for manipulating configuration objects.
+ **/
+void
+config_mgr_freeze(config_mgr_t *mgr)
+{
+  static uint64_t mgr_count = 0;
+
+  smartlist_sort(mgr->all_vars, managed_var_cmp);
+  memcpy(&mgr->toplevel_magic, &mgr->toplevel->magic,
+         sizeof(struct_magic_decl_t));
+  uint64_t magic_input[3] = { mgr->toplevel_magic.magic_val,
+                              (uint64_t) (uintptr_t) mgr,
+                              ++mgr_count };
+  mgr->toplevel_magic.magic_val =
+    (uint32_t)siphash24g(magic_input, sizeof(magic_input));
+  mgr->frozen = true;
+}
+
+/** Release all storage held in <b>mgr</b> */
+void
+config_mgr_free_(config_mgr_t *mgr)
+{
+  if (!mgr)
+    return;
+  SMARTLIST_FOREACH(mgr->all_vars, managed_var_t *, mv, managed_var_free(mv));
+  smartlist_free(mgr->all_vars);
+  smartlist_free(mgr->all_abbrevs);
+  smartlist_free(mgr->all_deprecations);
+  smartlist_free(mgr->subconfigs);
+  memset(mgr, 0, sizeof(*mgr));
+  tor_free(mgr);
+}
+
+/** Return a new smartlist_t containing a config_var_t for every variable that
+ * <b>mgr</b> knows about.  The elements of this smartlist do not need
+ * to be freed; they have the same lifespan as <b>mgr</b>. */
+smartlist_t *
+config_mgr_list_vars(const config_mgr_t *mgr)
+{
+  smartlist_t *result = smartlist_new();
+  tor_assert(mgr);
+  SMARTLIST_FOREACH(mgr->all_vars, managed_var_t *, mv,
+                    smartlist_add(result, (void*) mv->cvar));
+  return result;
+}
+
+/** Return a new smartlist_t containing the names of all deprecated variables.
+ * The elements of this smartlist do not need to be freed; they have the same
+ * lifespan as <b>mgr</b>.
+ */
+smartlist_t *
+config_mgr_list_deprecated_vars(const config_mgr_t *mgr)
+{
+  smartlist_t *result = smartlist_new();
+  tor_assert(mgr);
+  SMARTLIST_FOREACH(mgr->all_deprecations, config_deprecation_t *, d,
+                    smartlist_add(result, (char*)d->name));
+  return result;
+}
+
+/** Assert that the magic fields in <b>options</b> and its subsidiary
+ * objects are all okay. */
+static void
+config_mgr_assert_magic_ok(const config_mgr_t *mgr,
+                           const void *options)
+{
+  tor_assert(mgr);
+  tor_assert(options);
+  tor_assert(mgr->frozen);
+  struct_check_magic(options, &mgr->toplevel_magic);
+
+  config_suite_t **suitep = config_mgr_get_suite_ptr(mgr, (void*)options);
+  if (suitep == NULL) {
+    tor_assert(smartlist_len(mgr->subconfigs) == 0);
+    return;
+  }
+
+  tor_assert(smartlist_len((*suitep)->configs) ==
+             smartlist_len(mgr->subconfigs));
+  SMARTLIST_FOREACH_BEGIN(mgr->subconfigs, const config_format_t *, fmt) {
+    void *obj = smartlist_get((*suitep)->configs, fmt_sl_idx);
+    tor_assert(obj);
+    struct_check_magic(obj, &fmt->magic);
+  } SMARTLIST_FOREACH_END(fmt);
+}
+
+/** Macro: assert that <b>cfg</b> has the right magic field for
+ * <b>mgr</b>. */
+#define CONFIG_CHECK(mgr, cfg) STMT_BEGIN                               \
+    config_mgr_assert_magic_ok((mgr), (cfg));                           \
+  STMT_END
 
 /** Allocate an empty configuration object of a given format type. */
 void *
-config_new(const config_format_t *fmt)
+config_new(const config_mgr_t *mgr)
 {
-  void *opts = tor_malloc_zero(fmt->size);
-  struct_set_magic(opts, &fmt->magic);
-  CONFIG_CHECK(fmt, opts);
+  tor_assert(mgr->frozen);
+  void *opts = tor_malloc_zero(mgr->toplevel->size);
+  struct_set_magic(opts, &mgr->toplevel_magic);
+  config_suite_t **suitep = config_mgr_get_suite_ptr(mgr, opts);
+  if (suitep) {
+    *suitep = config_suite_new();
+    SMARTLIST_FOREACH_BEGIN(mgr->subconfigs, const config_format_t *, fmt) {
+      void *obj = tor_malloc_zero(fmt->size);
+      struct_set_magic(obj, &fmt->magic);
+      smartlist_add((*suitep)->configs, obj);
+    } SMARTLIST_FOREACH_END(fmt);
+  }
+  CONFIG_CHECK(mgr, opts);
   return opts;
 }
 
@@ -60,29 +393,26 @@ config_new(const config_format_t *fmt)
  * apply abbreviations that work for the config file and the command line.
  * If <b>warn_obsolete</b> is set, warn about deprecated names. */
 const char *
-config_expand_abbrev(const config_format_t *fmt, const char *option,
+config_expand_abbrev(const config_mgr_t *mgr, const char *option,
                      int command_line, int warn_obsolete)
 {
-  int i;
-  if (! fmt->abbrevs)
-    return option;
-  for (i=0; fmt->abbrevs[i].abbreviated; ++i) {
+  SMARTLIST_FOREACH_BEGIN(mgr->all_abbrevs, const config_abbrev_t *, abbrev) {
     /* Abbreviations are case insensitive. */
-    if (!strcasecmp(option,fmt->abbrevs[i].abbreviated) &&
-        (command_line || !fmt->abbrevs[i].commandline_only)) {
-      if (warn_obsolete && fmt->abbrevs[i].warn) {
+    if (!strcasecmp(option, abbrev->abbreviated) &&
+        (command_line || !abbrev->commandline_only)) {
+      if (warn_obsolete && abbrev->warn) {
         log_warn(LD_CONFIG,
                  "The configuration option '%s' is deprecated; "
                  "use '%s' instead.",
-                 fmt->abbrevs[i].abbreviated,
-                 fmt->abbrevs[i].full);
+                 abbrev->abbreviated,
+                 abbrev->full);
       }
       /* Keep going through the list in case we want to rewrite it more.
        * (We could imagine recursing here, but I don't want to get the
        * user into an infinite loop if we craft our list wrong.) */
-      option = fmt->abbrevs[i].full;
+      option = abbrev->full;
     }
-  }
+  } SMARTLIST_FOREACH_END(abbrev);
   return option;
 }
 
@@ -90,61 +420,92 @@ config_expand_abbrev(const config_format_t *fmt, const char *option,
  * explaining why it is deprecated (which may be an empty string). Return NULL
  * if it is not deprecated. The <b>key</b> field must be fully expanded. */
 const char *
-config_find_deprecation(const config_format_t *fmt, const char *key)
+config_find_deprecation(const config_mgr_t *mgr, const char *key)
 {
-  if (BUG(fmt == NULL) || BUG(key == NULL))
+  if (BUG(mgr == NULL) || BUG(key == NULL))
     return NULL; // LCOV_EXCL_LINE
-  if (fmt->deprecations == NULL)
-    return NULL;
 
-  const config_deprecation_t *d;
-  for (d = fmt->deprecations; d->name; ++d) {
+  SMARTLIST_FOREACH_BEGIN(mgr->all_deprecations, const config_deprecation_t *,
+                          d) {
     if (!strcasecmp(d->name, key)) {
       return d->why_deprecated ? d->why_deprecated : "";
     }
-  }
+  } SMARTLIST_FOREACH_END(d);
   return NULL;
 }
 
-/** If <b>key</b> is a configuration option, return the corresponding const
- * config_var_t.  Otherwise, if <b>key</b> is a non-standard abbreviation,
- * warn, and return the corresponding const config_var_t.  Otherwise return
- * NULL.
+/**
+ * Find the managed_var_t object for a variable whose name is <b>name</b>
+ * according to <b>mgr</b>.   Return that object, or NULL if none exists.
+ *
+ * If <b>allow_truncated</b> is true, then accept any variable whose
+ * name begins with <b>name</b>.
+ *
+ * If <b>idx_out</b> is not NULL, set *<b>idx_out</b> to the position of
+ * that variable within mgr-&gt;all_vars, or to -1 if the variable is
+ * not found.
  */
-const config_var_t *
-config_find_option(const config_format_t *fmt, const char *key)
+static const managed_var_t *
+config_mgr_find_var(const config_mgr_t *mgr,
+                    const char *key,
+                    bool allow_truncated, int *idx_out)
 {
-  int i;
-  size_t keylen = strlen(key);
+  const size_t keylen = strlen(key);
+  if (idx_out)
+    *idx_out = -1;
+
   if (!keylen)
     return NULL; /* if they say "--" on the command line, it's not an option */
+
   /* First, check for an exact (case-insensitive) match */
-  for (i=0; fmt->vars[i].member.name; ++i) {
-    if (!strcasecmp(key, fmt->vars[i].member.name)) {
-      return &fmt->vars[i];
+  SMARTLIST_FOREACH_BEGIN(mgr->all_vars, const managed_var_t *, mv) {
+    if (!strcasecmp(mv->cvar->member.name, key)) {
+      if (idx_out)
+        *idx_out = mv_sl_idx;
+      return mv;
     }
-  }
+  } SMARTLIST_FOREACH_END(mv);
+
+  if (!allow_truncated)
+    return NULL;
+
   /* If none, check for an abbreviated match */
-  for (i=0; fmt->vars[i].member.name; ++i) {
-    if (!strncasecmp(key, fmt->vars[i].member.name, keylen)) {
+  SMARTLIST_FOREACH_BEGIN(mgr->all_vars, const managed_var_t *, mv) {
+    if (!strncasecmp(key, mv->cvar->member.name, keylen)) {
       log_warn(LD_CONFIG, "The abbreviation '%s' is deprecated. "
                "Please use '%s' instead",
-               key, fmt->vars[i].member.name);
-      return &fmt->vars[i];
+               key, mv->cvar->member.name);
+      if (idx_out)
+        *idx_out = mv_sl_idx;
+      return mv;
     }
-  }
+  } SMARTLIST_FOREACH_END(mv);
+
   /* Okay, unrecognized option */
   return NULL;
 }
 
+/**
+ * If <b>key</b> is a name or an abbreviation configuration option, return
+ * the corresponding canonical name for it.  Warn if the abbreviation is
+ * non-standard.  Return NULL if the option does not exist.
+ */
+const char *
+config_find_option_name(const config_mgr_t *mgr, const char *key)
+{
+  key = config_expand_abbrev(mgr, key, 0, 0);
+  const managed_var_t *mv = config_mgr_find_var(mgr, key, true, NULL);
+  if (mv)
+    return mv->cvar->member.name;
+  else
+    return NULL;
+}
+
 /** Return the number of option entries in <b>fmt</b>. */
 static int
-config_count_options(const config_format_t *fmt)
+config_count_options(const config_mgr_t *mgr)
 {
-  int i;
-  for (i=0; fmt->vars[i].member.name; ++i)
-    ;
-  return i;
+  return smartlist_len(mgr->all_vars);
 }
 
 bool
@@ -185,33 +546,33 @@ config_var_is_dumpable(const config_var_t *var)
  * Called from config_assign_line() and option_reset().
  */
 static int
-config_assign_value(const config_format_t *fmt, void *options,
+config_assign_value(const config_mgr_t *mgr, void *options,
                     config_line_t *c, char **msg)
 {
-  const config_var_t *var;
+  const managed_var_t *var;
 
-  CONFIG_CHECK(fmt, options);
+  CONFIG_CHECK(mgr, options);
 
-  var = config_find_option(fmt, c->key);
+  var = config_mgr_find_var(mgr, c->key, true, NULL);
   tor_assert(var);
-  tor_assert(!strcmp(c->key, var->member.name));
+  tor_assert(!strcmp(c->key, var->cvar->member.name));
+  void *object = config_mgr_get_obj_mutable(mgr, options, var->object_idx);
 
-  return struct_var_kvassign(options, c, msg, &var->member);
+  return struct_var_kvassign(object, c, msg, &var->cvar->member);
 }
 
 /** Mark every linelist in <b>options</b> "fragile", so that fresh assignments
  * to it will replace old ones. */
 static void
-config_mark_lists_fragile(const config_format_t *fmt, void *options)
+config_mark_lists_fragile(const config_mgr_t *mgr, void *options)
 {
-  int i;
-  tor_assert(fmt);
+  tor_assert(mgr);
   tor_assert(options);
 
-  for (i = 0; fmt->vars[i].member.name; ++i) {
-    const config_var_t *var = &fmt->vars[i];
-    struct_var_mark_fragile(options, &var->member);
-  }
+  SMARTLIST_FOREACH_BEGIN(mgr->all_vars, const managed_var_t *, mv) {
+    void *object = config_mgr_get_obj_mutable(mgr, options, mv->object_idx);
+    struct_var_mark_fragile(object, &mv->cvar->member);
+  } SMARTLIST_FOREACH_END(mv);
 }
 
 void
@@ -234,19 +595,21 @@ warn_deprecated_option(const char *what, const char *why)
  * Called from config_assign().
  */
 static int
-config_assign_line(const config_format_t *fmt, void *options,
+config_assign_line(const config_mgr_t *mgr, void *options,
                    config_line_t *c, unsigned flags,
                    bitarray_t *options_seen, char **msg)
 {
   const unsigned use_defaults = flags & CAL_USE_DEFAULTS;
   const unsigned clear_first = flags & CAL_CLEAR_FIRST;
   const unsigned warn_deprecations = flags & CAL_WARN_DEPRECATIONS;
-  const config_var_t *var;
+  const managed_var_t *mvar;
 
-  CONFIG_CHECK(fmt, options);
+  CONFIG_CHECK(mgr, options);
 
-  var = config_find_option(fmt, c->key);
-  if (!var) {
+  int var_index = -1;
+  mvar = config_mgr_find_var(mgr, c->key, true, &var_index);
+  if (!mvar) {
+    const config_format_t *fmt = mgr->toplevel;
     if (fmt->extra) {
       void *lvalue = STRUCT_VAR_P(options, fmt->extra->offset);
       log_info(LD_CONFIG,
@@ -260,49 +623,52 @@ config_assign_line(const config_format_t *fmt, void *options,
     }
   }
 
+  const config_var_t *cvar = mvar->cvar;
+  tor_assert(cvar);
+
   /* Put keyword into canonical case. */
-  if (strcmp(var->member.name, c->key)) {
+  if (strcmp(cvar->member.name, c->key)) {
     tor_free(c->key);
-    c->key = tor_strdup(var->member.name);
+    c->key = tor_strdup(cvar->member.name);
   }
 
   const char *deprecation_msg;
   if (warn_deprecations &&
-      (deprecation_msg = config_find_deprecation(fmt, var->member.name))) {
-    warn_deprecated_option(var->member.name, deprecation_msg);
+      (deprecation_msg = config_find_deprecation(mgr, cvar->member.name))) {
+    warn_deprecated_option(cvar->member.name, deprecation_msg);
   }
 
   if (!strlen(c->value)) {
     /* reset or clear it, then return */
     if (!clear_first) {
-      if (config_var_is_cumulative(var) && c->command != CONFIG_LINE_CLEAR) {
+      if (config_var_is_cumulative(cvar) && c->command != CONFIG_LINE_CLEAR) {
         /* We got an empty linelist from the torrc or command line.
            As a special case, call this an error. Warn and ignore. */
         log_warn(LD_CONFIG,
                  "Linelist option '%s' has no value. Skipping.", c->key);
       } else { /* not already cleared */
-        config_reset(fmt, options, var, use_defaults);
+        config_reset(mgr, options, mvar, use_defaults);
       }
     }
     return 0;
   } else if (c->command == CONFIG_LINE_CLEAR && !clear_first) {
     // XXXX This is unreachable, since a CLEAR line always has an
     // XXXX empty value.
-    config_reset(fmt, options, var, use_defaults); // LCOV_EXCL_LINE
+    config_reset(mgr, options, mvar, use_defaults); // LCOV_EXCL_LINE
   }
 
-  if (options_seen && ! config_var_is_cumulative(var)) {
+  if (options_seen && ! config_var_is_cumulative(cvar)) {
     /* We're tracking which options we've seen, and this option is not
      * supposed to occur more than once. */
-    int var_index = (int)(var - fmt->vars);
+    tor_assert(var_index >= 0);
     if (bitarray_is_set(options_seen, var_index)) {
       log_warn(LD_CONFIG, "Option '%s' used more than once; all but the last "
-               "value will be ignored.", var->member.name);
+               "value will be ignored.", cvar->member.name);
     }
     bitarray_set(options_seen, var_index);
   }
 
-  if (config_assign_value(fmt, options, c, msg) < 0)
+  if (config_assign_value(mgr, options, c, msg) < 0)
     return -2;
   return 0;
 }
@@ -310,18 +676,18 @@ config_assign_line(const config_format_t *fmt, void *options,
 /** Restore the option named <b>key</b> in options to its default value.
  * Called from config_assign(). */
 STATIC void
-config_reset_line(const config_format_t *fmt, void *options,
+config_reset_line(const config_mgr_t *mgr, void *options,
                   const char *key, int use_defaults)
 {
-  const config_var_t *var;
+  const managed_var_t *var;
 
-  CONFIG_CHECK(fmt, options);
+  CONFIG_CHECK(mgr, options);
 
-  var = config_find_option(fmt, key);
+  var = config_mgr_find_var(mgr, key, true, NULL);
   if (!var)
     return; /* give error on next pass. */
 
-  config_reset(fmt, options, var, use_defaults);
+  config_reset(mgr, options, var, use_defaults);
 }
 
 /** Return true iff value needs to be quoted and escaped to be used in
@@ -355,22 +721,24 @@ config_value_needs_escape(const char *value)
  * value needs to be quoted before it's put in a config file, quote and
  * escape that value. Return NULL if no such key exists. */
 config_line_t *
-config_get_assigned_option(const config_format_t *fmt, const void *options,
+config_get_assigned_option(const config_mgr_t *mgr, const void *options,
                            const char *key, int escape_val)
 {
-  const config_var_t *var;
+  const managed_var_t *var;
   config_line_t *result;
+
   tor_assert(options && key);
 
-  CONFIG_CHECK(fmt, options);
+  CONFIG_CHECK(mgr, options);
 
-  var = config_find_option(fmt, key);
+  var = config_mgr_find_var(mgr, key, true, NULL);
   if (!var) {
     log_warn(LD_CONFIG, "Unknown option '%s'.  Failing.", key);
     return NULL;
   }
+  const void *object = config_mgr_get_obj(mgr, options, var->object_idx);
 
-  result = struct_var_kvencode(options, &var->member);
+  result = struct_var_kvencode(object, &var->cvar->member);
 
   if (escape_val) {
     config_line_t *line;
@@ -442,20 +810,20 @@ options_trial_assign() calls config_assign(1, 1)
     returns.
 */
 int
-config_assign(const config_format_t *fmt, void *options, config_line_t *list,
+config_assign(const config_mgr_t *mgr, void *options, config_line_t *list,
               unsigned config_assign_flags, char **msg)
 {
   config_line_t *p;
   bitarray_t *options_seen;
-  const int n_options = config_count_options(fmt);
+  const int n_options = config_count_options(mgr);
   const unsigned clear_first = config_assign_flags & CAL_CLEAR_FIRST;
   const unsigned use_defaults = config_assign_flags & CAL_USE_DEFAULTS;
 
-  CONFIG_CHECK(fmt, options);
+  CONFIG_CHECK(mgr, options);
 
   /* pass 1: normalize keys */
   for (p = list; p; p = p->next) {
-    const char *full = config_expand_abbrev(fmt, p->key, 0, 1);
+    const char *full = config_expand_abbrev(mgr, p->key, 0, 1);
     if (strcmp(full,p->key)) {
       tor_free(p->key);
       p->key = tor_strdup(full);
@@ -466,14 +834,14 @@ config_assign(const config_format_t *fmt, void *options, config_line_t *list,
    * mentioned config options, and maybe set to their defaults. */
   if (clear_first) {
     for (p = list; p; p = p->next)
-      config_reset_line(fmt, options, p->key, use_defaults);
+      config_reset_line(mgr, options, p->key, use_defaults);
   }
 
   options_seen = bitarray_init_zero(n_options);
   /* pass 3: assign. */
   while (list) {
     int r;
-    if ((r=config_assign_line(fmt, options, list, config_assign_flags,
+    if ((r=config_assign_line(mgr, options, list, config_assign_flags,
                               options_seen, msg))) {
       bitarray_free(options_seen);
       return r;
@@ -485,7 +853,7 @@ config_assign(const config_format_t *fmt, void *options, config_line_t *list,
   /** Now we're done assigning a group of options to the configuration.
    * Subsequent group assignments should _replace_ linelists, not extend
    * them. */
-  config_mark_lists_fragile(fmt, options);
+  config_mark_lists_fragile(mgr, options);
 
   return 0;
 }
@@ -493,33 +861,32 @@ config_assign(const config_format_t *fmt, void *options, config_line_t *list,
 /** Reset config option <b>var</b> to 0, 0.0, NULL, or the equivalent.
  * Called from config_reset() and config_free(). */
 static void
-config_clear(const config_format_t *fmt, void *options,
-             const config_var_t *var)
+config_clear(const config_mgr_t *mgr, void *options, const managed_var_t *var)
 {
-
-  (void)fmt; /* unused */
-
-  struct_var_free(options, &var->member);
+  void *object = config_mgr_get_obj_mutable(mgr, options, var->object_idx);
+  struct_var_free(object, &var->cvar->member);
 }
 
 /** Clear the option indexed by <b>var</b> in <b>options</b>. Then if
  * <b>use_defaults</b>, set it to its default value.
  * Called by config_init() and option_reset_line() and option_assign_line(). */
 static void
-config_reset(const config_format_t *fmt, void *options,
-             const config_var_t *var, int use_defaults)
+config_reset(const config_mgr_t *mgr, void *options,
+             const managed_var_t *var, int use_defaults)
 {
   config_line_t *c;
   char *msg = NULL;
-  CONFIG_CHECK(fmt, options);
-  config_clear(fmt, options, var); /* clear it first */
+  CONFIG_CHECK(mgr, options);
+  config_clear(mgr, options, var); /* clear it first */
+
   if (!use_defaults)
     return; /* all done */
-  if (var->initvalue) {
+
+  if (var->cvar->initvalue) {
     c = tor_malloc_zero(sizeof(config_line_t));
-    c->key = tor_strdup(var->member.name);
-    c->value = tor_strdup(var->initvalue);
-    if (config_assign_value(fmt, options, c, &msg) < 0) {
+    c->key = tor_strdup(var->cvar->member.name);
+    c->value = tor_strdup(var->cvar->initvalue);
+    if (config_assign_value(mgr, options, c, &msg) < 0) {
       // LCOV_EXCL_START
       log_warn(LD_BUG, "Failed to assign default: %s", msg);
       tor_free(msg); /* if this happens it's a bug */
@@ -531,23 +898,44 @@ config_reset(const config_format_t *fmt, void *options,
 
 /** Release storage held by <b>options</b>. */
 void
-config_free_(const config_format_t *fmt, void *options)
+config_free_(const config_mgr_t *mgr, void *options)
 {
-  int i;
-
   if (!options)
     return;
 
-  tor_assert(fmt);
+  tor_assert(mgr);
 
-  for (i=0; fmt->vars[i].member.name; ++i)
-    config_clear(fmt, options, &(fmt->vars[i]));
+  if (mgr->toplevel->clear_fn) {
+    mgr->toplevel->clear_fn(mgr, options);
+  }
+  config_suite_t **suitep = config_mgr_get_suite_ptr(mgr, options);
+  if (suitep) {
+    tor_assert(smartlist_len((*suitep)->configs) ==
+               smartlist_len(mgr->subconfigs));
+    SMARTLIST_FOREACH_BEGIN(mgr->subconfigs, const config_format_t *, fmt) {
+      void *obj = smartlist_get((*suitep)->configs, fmt_sl_idx);
+      if (fmt->clear_fn) {
+        fmt->clear_fn(mgr, obj);
+      }
+    } SMARTLIST_FOREACH_END(fmt);
+  }
 
-  if (fmt->extra) {
-    config_line_t **linep = STRUCT_VAR_P(options, fmt->extra->offset);
+  SMARTLIST_FOREACH_BEGIN(mgr->all_vars, const managed_var_t *, mv) {
+    config_clear(mgr, options, mv);
+  } SMARTLIST_FOREACH_END(mv);
+
+  if (mgr->toplevel->extra) {
+    config_line_t **linep = STRUCT_VAR_P(options,
+                                         mgr->toplevel->extra->offset);
     config_free_lines(*linep);
     *linep = NULL;
   }
+
+  if (suitep) {
+    SMARTLIST_FOREACH((*suitep)->configs, void *, obj, tor_free(obj));
+    config_suite_free(*suitep);
+  }
+
   tor_free(options);
 }
 
@@ -555,59 +943,103 @@ config_free_(const config_format_t *fmt, void *options)
  * and <b>o2</b>.  Must not be called for LINELIST_S or OBSOLETE options.
  */
 int
-config_is_same(const config_format_t *fmt,
+config_is_same(const config_mgr_t *mgr,
                const void *o1, const void *o2,
                const char *name)
 {
-  CONFIG_CHECK(fmt, o1);
-  CONFIG_CHECK(fmt, o2);
+  CONFIG_CHECK(mgr, o1);
+  CONFIG_CHECK(mgr, o2);
 
-  const config_var_t *var = config_find_option(fmt, name);
+  const managed_var_t *var = config_mgr_find_var(mgr, name, true, NULL);
   if (!var) {
     return true;
   }
+  const void *obj1 = config_mgr_get_obj(mgr, o1, var->object_idx);
+  const void *obj2 = config_mgr_get_obj(mgr, o2, var->object_idx);
 
-  return struct_var_eq(o1, o2, &var->member);
+  return struct_var_eq(obj1, obj2, &var->cvar->member);
+}
+
+/**
+ * Return a list of the options which have changed between <b>options1</b> and
+ * <b>options2</b>. If an option has reverted to its default value, it has a
+ * value entry of NULL.
+ *
+ * <b>options1</b> and <b>options2</b> must be top-level configuration objects
+ * of the type managed by <b>mgr</b>.
+ **/
+config_line_t *
+config_get_changes(const config_mgr_t *mgr,
+                   const void *options1, const void *options2)
+{
+  config_line_t *result = NULL;
+  config_line_t **next = &result;
+  SMARTLIST_FOREACH_BEGIN(mgr->all_vars, managed_var_t *, mv) {
+    if (config_var_is_contained(mv->cvar)) {
+      /* something else will check this var, or it doesn't need checking */
+      continue;
+    }
+    const void *obj1 = config_mgr_get_obj(mgr, options1, mv->object_idx);
+    const void *obj2 = config_mgr_get_obj(mgr, options2, mv->object_idx);
+
+    if (struct_var_eq(obj1, obj2, &mv->cvar->member)) {
+      continue;
+    }
+
+    const char *varname = mv->cvar->member.name;
+    config_line_t *line =
+      config_get_assigned_option(mgr, options2, varname, 1);
+
+    if (line) {
+      *next = line;
+    } else {
+      *next = tor_malloc_zero(sizeof(config_line_t));
+      (*next)->key = tor_strdup(varname);
+    }
+    while (*next)
+      next = &(*next)->next;
+  } SMARTLIST_FOREACH_END(mv);
+
+  return result;
 }
 
 /** Copy storage held by <b>old</b> into a new or_options_t and return it. */
 void *
-config_dup(const config_format_t *fmt, const void *old)
+config_dup(const config_mgr_t *mgr, const void *old)
 {
   void *newopts;
-  int i;
 
-  newopts = config_new(fmt);
-  for (i=0; fmt->vars[i].member.name; ++i) {
-    if (config_var_is_contained(&fmt->vars[i])) {
+  newopts = config_new(mgr);
+  SMARTLIST_FOREACH_BEGIN(mgr->all_vars, managed_var_t *, mv) {
+    if (config_var_is_contained(mv->cvar)) {
       // Something else will copy this option, or it doesn't need copying.
       continue;
     }
-    if (struct_var_copy(newopts, old, &fmt->vars[i].member) < 0) {
+    const void *oldobj = config_mgr_get_obj(mgr, old, mv->object_idx);
+    void *newobj = config_mgr_get_obj_mutable(mgr, newopts, mv->object_idx);
+    if (struct_var_copy(newobj, oldobj, &mv->cvar->member) < 0) {
       // LCOV_EXCL_START
       log_err(LD_BUG, "Unable to copy value for %s.",
-              fmt->vars[i].member.name);
+              mv->cvar->member.name);
       tor_assert_unreached();
       // LCOV_EXCL_STOP
     }
-  }
+  } SMARTLIST_FOREACH_END(mv);
+
   return newopts;
 }
 /** Set all vars in the configuration object <b>options</b> to their default
  * values. */
 void
-config_init(const config_format_t *fmt, void *options)
+config_init(const config_mgr_t *mgr, void *options)
 {
-  int i;
-  const config_var_t *var;
-  CONFIG_CHECK(fmt, options);
+  CONFIG_CHECK(mgr, options);
 
-  for (i=0; fmt->vars[i].member.name; ++i) {
-    var = &fmt->vars[i];
-    if (!var->initvalue)
+  SMARTLIST_FOREACH_BEGIN(mgr->all_vars, const managed_var_t *, mv) {
+    if (!mv->cvar->initvalue)
       continue; /* defaults to NULL or 0 */
-    config_reset(fmt, options, var, 1);
-  }
+    config_reset(mgr, options, mv, 1);
+  } SMARTLIST_FOREACH_END(mv);
 }
 
 /** Allocate and return a new string holding the written-out values of the vars
@@ -615,21 +1047,21 @@ config_init(const config_format_t *fmt, void *options)
  * Else, if comment_defaults, write default values as comments.
  */
 char *
-config_dump(const config_format_t *fmt, const void *default_options,
+config_dump(const config_mgr_t *mgr, const void *default_options,
             const void *options, int minimal,
             int comment_defaults)
 {
+  const config_format_t *fmt = mgr->toplevel;
   smartlist_t *elements;
   const void *defaults = default_options;
   void *defaults_tmp = NULL;
   config_line_t *line, *assigned;
   char *result;
-  int i;
   char *msg = NULL;
 
   if (defaults == NULL) {
-    defaults = defaults_tmp = config_new(fmt);
-    config_init(fmt, defaults_tmp);
+    defaults = defaults_tmp = config_new(mgr);
+    config_init(mgr, defaults_tmp);
   }
 
   /* XXX use a 1 here so we don't add a new log line while dumping */
@@ -644,24 +1076,24 @@ config_dump(const config_format_t *fmt, const void *default_options,
   }
 
   elements = smartlist_new();
-  for (i=0; fmt->vars[i].member.name; ++i) {
+  SMARTLIST_FOREACH_BEGIN(mgr->all_vars, managed_var_t *, mv) {
     int comment_option = 0;
-    if (config_var_is_contained(&fmt->vars[i])) {
+    if (config_var_is_contained(mv->cvar)) {
       // Something else will dump this option, or it doesn't need dumping.
       continue;
     }
     /* Don't save 'hidden' control variables. */
-    if (! config_var_is_dumpable(&fmt->vars[i]))
+    if (! config_var_is_dumpable(mv->cvar))
       continue;
-    if (minimal && config_is_same(fmt, options, defaults,
-                                  fmt->vars[i].member.name))
+    const char *name = mv->cvar->member.name;
+    if (minimal && config_is_same(mgr, options, defaults, name))
       continue;
     else if (comment_defaults &&
-             config_is_same(fmt, options, defaults, fmt->vars[i].member.name))
+             config_is_same(mgr, options, defaults, name))
       comment_option = 1;
 
     line = assigned =
-      config_get_assigned_option(fmt, options, fmt->vars[i].member.name, 1);
+      config_get_assigned_option(mgr, options, name, 1);
 
     for (; line; line = line->next) {
       if (!strcmpstart(line->key, "__")) {
@@ -674,7 +1106,7 @@ config_dump(const config_format_t *fmt, const void *default_options,
                    line->key, line->value);
     }
     config_free_lines(assigned);
-  }
+  } SMARTLIST_FOREACH_END(mv);
 
   if (fmt->extra) {
     line = *(config_line_t**)STRUCT_VAR_P(options, fmt->extra->offset);
@@ -686,9 +1118,7 @@ config_dump(const config_format_t *fmt, const void *default_options,
   result = smartlist_join_strings(elements, "", 0, NULL);
   SMARTLIST_FOREACH(elements, char *, cp, tor_free(cp));
   smartlist_free(elements);
-  if (defaults_tmp) {
-    fmt->free_fn(defaults_tmp);
-  }
+  config_free(mgr, defaults_tmp);
   return result;
 }
 
@@ -697,15 +1127,17 @@ config_dump(const config_format_t *fmt, const void *default_options,
  * Return false otherwise.  Log errors at level <b>severity</b>.
  */
 bool
-config_check_ok(const config_format_t *fmt, const void *options, int severity)
+config_check_ok(const config_mgr_t *mgr, const void *options, int severity)
 {
   bool all_ok = true;
-  for (int i=0; fmt->vars[i].member.name; ++i) {
-    if (!struct_var_ok(options, &fmt->vars[i].member)) {
+
+  SMARTLIST_FOREACH_BEGIN(mgr->all_vars, const managed_var_t *, mv) {
+    if (!struct_var_ok(options, &mv->cvar->member)) {
       log_fn(severity, LD_BUG, "Invalid value for %s",
-             fmt->vars[i].member.name);
+             mv->cvar->member.name);
       all_ok = false;
     }
-  }
+  } SMARTLIST_FOREACH_END(mv);
+
   return all_ok;
 }