Split command-handling and authentication from control.c

1 files changed, 2323 insertions, 0 deletions

diff --git a/src/feature/control/control_cmd.c b/src/feature/control/control_cmd.c
new file mode 100644
index 0000000000..95cf0d561e
--- /dev/null
+++ b/src/feature/control/control_cmd.c
@@ -0,0 +1,2323 @@
+/* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
+ * Copyright (c) 2007-2019, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+
+/**
+ * \file control_cmd.c
+ * \brief Implement various commands for Tor's control-socket interface.
+ **/
+
+#define CONTROL_MODULE_PRIVATE
+#define CONTROL_CMD_PRIVATE
+#define CONTROL_EVENTS_PRIVATE
+
+#include "core/or/or.h"
+#include "app/config/config.h"
+#include "app/config/confparse.h"
+#include "app/main/main.h"
+#include "core/mainloop/connection.h"
+#include "core/or/circuitbuild.h"
+#include "core/or/circuitlist.h"
+#include "core/or/circuituse.h"
+#include "core/or/connection_edge.h"
+#include "feature/client/addressmap.h"
+#include "feature/client/dnsserv.h"
+#include "feature/client/entrynodes.h"
+#include "feature/control/control.h"
+#include "feature/control/control_auth.h"
+#include "feature/control/control_cmd.h"
+#include "feature/control/control_events.h"
+#include "feature/control/control_fmt.h"
+#include "feature/control/control_getinfo.h"
+#include "feature/hs/hs_control.h"
+#include "feature/nodelist/nodelist.h"
+#include "feature/nodelist/routerinfo.h"
+#include "feature/nodelist/routerlist.h"
+#include "feature/rend/rendclient.h"
+#include "feature/rend/rendcommon.h"
+#include "feature/rend/rendparse.h"
+#include "feature/rend/rendservice.h"
+#include "lib/crypt_ops/crypto_rand.h"
+#include "lib/crypt_ops/crypto_util.h"
+#include "lib/encoding/confline.h"
+
+#include "core/or/cpath_build_state_st.h"
+#include "core/or/entry_connection_st.h"
+#include "core/or/origin_circuit_st.h"
+#include "core/or/socks_request_st.h"
+#include "feature/control/control_connection_st.h"
+#include "feature/nodelist/node_st.h"
+#include "feature/nodelist/routerinfo_st.h"
+#include "feature/rend/rend_authorized_client_st.h"
+#include "feature/rend/rend_encoded_v2_service_descriptor_st.h"
+#include "feature/rend/rend_service_descriptor_st.h"
+
+static int control_setconf_helper(control_connection_t *conn, uint32_t len,
+                                  char *body,
+                                  int use_defaults);
+
+/** Yield true iff <b>s</b> is the state of a control_connection_t that has
+ * finished authentication and is accepting commands. */
+#define STATE_IS_OPEN(s) ((s) == CONTROL_CONN_STATE_OPEN)
+
+/** Called when we receive a SETCONF message: parse the body and try
+ * to update our configuration.  Reply with a DONE or ERROR message.
+ * Modifies the contents of body.*/
+static int
+handle_control_setconf(control_connection_t *conn, uint32_t len, char *body)
+{
+  return control_setconf_helper(conn, len, body, 0);
+}
+
+/** Called when we receive a RESETCONF message: parse the body and try
+ * to update our configuration.  Reply with a DONE or ERROR message.
+ * Modifies the contents of body. */
+static int
+handle_control_resetconf(control_connection_t *conn, uint32_t len, char *body)
+{
+  return control_setconf_helper(conn, len, body, 1);
+}
+
+/** Called when we receive a GETCONF message.  Parse the request, and
+ * reply with a CONFVALUE or an ERROR message */
+static int
+handle_control_getconf(control_connection_t *conn, uint32_t body_len,
+                       const char *body)
+{
+  smartlist_t *questions = smartlist_new();
+  smartlist_t *answers = smartlist_new();
+  smartlist_t *unrecognized = smartlist_new();
+  char *msg = NULL;
+  size_t msg_len;
+  const or_options_t *options = get_options();
+  int i, len;
+
+  (void) body_len; /* body is NUL-terminated; so we can ignore len. */
+  smartlist_split_string(questions, body, " ",
+                         SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, 0);
+  SMARTLIST_FOREACH_BEGIN(questions, const char *, q) {
+    if (!option_is_recognized(q)) {
+      smartlist_add(unrecognized, (char*) q);
+    } else {
+      config_line_t *answer = option_get_assignment(options,q);
+      if (!answer) {
+        const char *name = option_get_canonical_name(q);
+        smartlist_add_asprintf(answers, "250-%s\r\n", name);
+      }
+
+      while (answer) {
+        config_line_t *next;
+        smartlist_add_asprintf(answers, "250-%s=%s\r\n",
+                     answer->key, answer->value);
+
+        next = answer->next;
+        tor_free(answer->key);
+        tor_free(answer->value);
+        tor_free(answer);
+        answer = next;
+      }
+    }
+  } SMARTLIST_FOREACH_END(q);
+
+  if ((len = smartlist_len(unrecognized))) {
+    for (i=0; i < len-1; ++i)
+      connection_printf_to_buf(conn,
+                               "552-Unrecognized configuration key \"%s\"\r\n",
+                               (char*)smartlist_get(unrecognized, i));
+    connection_printf_to_buf(conn,
+                             "552 Unrecognized configuration key \"%s\"\r\n",
+                             (char*)smartlist_get(unrecognized, len-1));
+  } else if ((len = smartlist_len(answers))) {
+    char *tmp = smartlist_get(answers, len-1);
+    tor_assert(strlen(tmp)>4);
+    tmp[3] = ' ';
+    msg = smartlist_join_strings(answers, "", 0, &msg_len);
+    connection_buf_add(msg, msg_len, TO_CONN(conn));
+  } else {
+    connection_write_str_to_buf("250 OK\r\n", conn);
+  }
+
+  SMARTLIST_FOREACH(answers, char *, cp, tor_free(cp));
+  smartlist_free(answers);
+  SMARTLIST_FOREACH(questions, char *, cp, tor_free(cp));
+  smartlist_free(questions);
+  smartlist_free(unrecognized);
+
+  tor_free(msg);
+
+  return 0;
+}
+
+/** Called when we get a +LOADCONF message. */
+static int
+handle_control_loadconf(control_connection_t *conn, uint32_t len,
+                         const char *body)
+{
+  setopt_err_t retval;
+  char *errstring = NULL;
+  const char *msg = NULL;
+  (void) len;
+
+  retval = options_init_from_string(NULL, body, CMD_RUN_TOR, NULL, &errstring);
+
+  if (retval != SETOPT_OK)
+    log_warn(LD_CONTROL,
+             "Controller gave us config file that didn't validate: %s",
+             errstring);
+
+  switch (retval) {
+  case SETOPT_ERR_PARSE:
+    msg = "552 Invalid config file";
+    break;
+  case SETOPT_ERR_TRANSITION:
+    msg = "553 Transition not allowed";
+    break;
+  case SETOPT_ERR_SETTING:
+    msg = "553 Unable to set option";
+    break;
+  case SETOPT_ERR_MISC:
+  default:
+    msg = "550 Unable to load config";
+    break;
+  case SETOPT_OK:
+    break;
+  }
+  if (msg) {
+    if (errstring)
+      connection_printf_to_buf(conn, "%s: %s\r\n", msg, errstring);
+    else
+      connection_printf_to_buf(conn, "%s\r\n", msg);
+  } else {
+    send_control_done(conn);
+  }
+  tor_free(errstring);
+  return 0;
+}
+
+/** Called when we get a SETEVENTS message: update conn->event_mask,
+ * and reply with DONE or ERROR. */
+static int
+handle_control_setevents(control_connection_t *conn, uint32_t len,
+                         const char *body)
+{
+  int event_code;
+  event_mask_t event_mask = 0;
+  smartlist_t *events = smartlist_new();
+
+  (void) len;
+
+  smartlist_split_string(events, body, " ",
+                         SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, 0);
+  SMARTLIST_FOREACH_BEGIN(events, const char *, ev)
+    {
+      if (!strcasecmp(ev, "EXTENDED") ||
+          !strcasecmp(ev, "AUTHDIR_NEWDESCS")) {
+        log_warn(LD_CONTROL, "The \"%s\" SETEVENTS argument is no longer "
+                 "supported.", ev);
+        continue;
+      } else {
+        int i;
+        event_code = -1;
+
+        for (i = 0; control_event_table[i].event_name != NULL; ++i) {
+          if (!strcasecmp(ev, control_event_table[i].event_name)) {
+            event_code = control_event_table[i].event_code;
+            break;
+          }
+        }
+
+        if (event_code == -1) {
+          connection_printf_to_buf(conn, "552 Unrecognized event \"%s\"\r\n",
+                                   ev);
+          SMARTLIST_FOREACH(events, char *, e, tor_free(e));
+          smartlist_free(events);
+          return 0;
+        }
+      }
+      event_mask |= (((event_mask_t)1) << event_code);
+    }
+  SMARTLIST_FOREACH_END(ev);
+  SMARTLIST_FOREACH(events, char *, e, tor_free(e));
+  smartlist_free(events);
+
+  conn->event_mask = event_mask;
+
+  control_update_global_event_mask();
+  send_control_done(conn);
+  return 0;
+}
+
+/** Called when we get a SAVECONF command. Try to flush the current options to
+ * disk, and report success or failure. */
+static int
+handle_control_saveconf(control_connection_t *conn, uint32_t len,
+                        const char *body)
+{
+  (void) len;
+
+  int force = !strcmpstart(body, "FORCE");
+  const or_options_t *options = get_options();
+  if ((!force && options->IncludeUsed) || options_save_current() < 0) {
+    connection_write_str_to_buf(
+      "551 Unable to write configuration to disk.\r\n", conn);
+  } else {
+    send_control_done(conn);
+  }
+  return 0;
+}
+
+/** Called when we get a SIGNAL command. React to the provided signal, and
+ * report success or failure. (If the signal results in a shutdown, success
+ * may not be reported.) */
+static int
+handle_control_signal(control_connection_t *conn, uint32_t len,
+                      const char *body)
+{
+  int sig = -1;
+  int i;
+  int n = 0;
+  char *s;
+
+  (void) len;
+
+  while (body[n] && ! TOR_ISSPACE(body[n]))
+    ++n;
+  s = tor_strndup(body, n);
+
+  for (i = 0; signal_table[i].signal_name != NULL; ++i) {
+    if (!strcasecmp(s, signal_table[i].signal_name)) {
+      sig = signal_table[i].sig;
+      break;
+    }
+  }
+
+  if (sig < 0)
+    connection_printf_to_buf(conn, "552 Unrecognized signal code \"%s\"\r\n",
+                             s);
+  tor_free(s);
+  if (sig < 0)
+    return 0;
+
+  send_control_done(conn);
+  /* Flush the "done" first if the signal might make us shut down. */
+  if (sig == SIGTERM || sig == SIGINT)
+    connection_flush(TO_CONN(conn));
+
+  activate_signal(sig);
+
+  return 0;
+}
+
+/** Called when we get a TAKEOWNERSHIP command.  Mark this connection
+ * as an owning connection, so that we will exit if the connection
+ * closes. */
+static int
+handle_control_takeownership(control_connection_t *conn, uint32_t len,
+                             const char *body)
+{
+  (void)len;
+  (void)body;
+
+  conn->is_owning_control_connection = 1;
+
+  log_info(LD_CONTROL, "Control connection %d has taken ownership of this "
+           "Tor instance.",
+           (int)(conn->base_.s));
+
+  send_control_done(conn);
+  return 0;
+}
+
+/** Called when we get a DROPOWNERSHIP command.  Mark this connection
+ * as a non-owning connection, so that we will not exit if the connection
+ * closes. */
+static int
+handle_control_dropownership(control_connection_t *conn, uint32_t len,
+                             const char *body)
+{
+  (void)len;
+  (void)body;
+
+  conn->is_owning_control_connection = 0;
+
+  log_info(LD_CONTROL, "Control connection %d has dropped ownership of this "
+           "Tor instance.",
+           (int)(conn->base_.s));
+
+  send_control_done(conn);
+  return 0;
+}
+
+/** Given a text circuit <b>id</b>, return the corresponding circuit. */
+static origin_circuit_t *
+get_circ(const char *id)
+{
+  uint32_t n_id;
+  int ok;
+  n_id = (uint32_t) tor_parse_ulong(id, 10, 0, UINT32_MAX, &ok, NULL);
+  if (!ok)
+    return NULL;
+  return circuit_get_by_global_id(n_id);
+}
+
+/** Given a text stream <b>id</b>, return the corresponding AP connection. */
+static entry_connection_t *
+get_stream(const char *id)
+{
+  uint64_t n_id;
+  int ok;
+  connection_t *conn;
+  n_id = tor_parse_uint64(id, 10, 0, UINT64_MAX, &ok, NULL);
+  if (!ok)
+    return NULL;
+  conn = connection_get_by_global_id(n_id);
+  if (!conn || conn->type != CONN_TYPE_AP || conn->marked_for_close)
+    return NULL;
+  return TO_ENTRY_CONN(conn);
+}
+
+/** Helper for setconf and resetconf. Acts like setconf, except
+ * it passes <b>use_defaults</b> on to options_trial_assign().  Modifies the
+ * contents of body.
+ */
+static int
+control_setconf_helper(control_connection_t *conn, uint32_t len, char *body,
+                       int use_defaults)
+{
+  setopt_err_t opt_err;
+  config_line_t *lines=NULL;
+  char *start = body;
+  char *errstring = NULL;
+  const unsigned flags =
+    CAL_CLEAR_FIRST | (use_defaults ? CAL_USE_DEFAULTS : 0);
+
+  char *config;
+  smartlist_t *entries = smartlist_new();
+
+  /* We have a string, "body", of the format '(key(=val|="val")?)' entries
+   * separated by space.  break it into a list of configuration entries. */
+  while (*body) {
+    char *eq = body;
+    char *key;
+    char *entry;
+    while (!TOR_ISSPACE(*eq) && *eq != '=')
+      ++eq;
+    key = tor_strndup(body, eq-body);
+    body = eq+1;
+    if (*eq == '=') {
+      char *val=NULL;
+      size_t val_len=0;
+      if (*body != '\"') {
+        char *val_start = body;
+        while (!TOR_ISSPACE(*body))
+          body++;
+        val = tor_strndup(val_start, body-val_start);
+        val_len = strlen(val);
+      } else {
+        body = (char*)extract_escaped_string(body, (len - (body-start)),
+                                             &val, &val_len);
+        if (!body) {
+          connection_write_str_to_buf("551 Couldn't parse string\r\n", conn);
+          SMARTLIST_FOREACH(entries, char *, cp, tor_free(cp));
+          smartlist_free(entries);
+          tor_free(key);
+          return 0;
+        }
+      }
+      tor_asprintf(&entry, "%s %s", key, val);
+      tor_free(key);
+      tor_free(val);
+    } else {
+      entry = key;
+    }
+    smartlist_add(entries, entry);
+    while (TOR_ISSPACE(*body))
+      ++body;
+  }
+
+  smartlist_add_strdup(entries, "");
+  config = smartlist_join_strings(entries, "\n", 0, NULL);
+  SMARTLIST_FOREACH(entries, char *, cp, tor_free(cp));
+  smartlist_free(entries);
+
+  if (config_get_lines(config, &lines, 0) < 0) {
+    log_warn(LD_CONTROL,"Controller gave us config lines we can't parse.");
+    connection_write_str_to_buf("551 Couldn't parse configuration\r\n",
+                                conn);
+    tor_free(config);
+    return 0;
+  }
+  tor_free(config);
+
+  opt_err = options_trial_assign(lines, flags, &errstring);
+  {
+    const char *msg;
+    switch (opt_err) {
+      case SETOPT_ERR_MISC:
+        msg = "552 Unrecognized option";
+        break;
+      case SETOPT_ERR_PARSE:
+        msg = "513 Unacceptable option value";
+        break;
+      case SETOPT_ERR_TRANSITION:
+        msg = "553 Transition not allowed";
+        break;
+      case SETOPT_ERR_SETTING:
+      default:
+        msg = "553 Unable to set option";
+        break;
+      case SETOPT_OK:
+        config_free_lines(lines);
+        send_control_done(conn);
+        return 0;
+    }
+    log_warn(LD_CONTROL,
+             "Controller gave us config lines that didn't validate: %s",
+             errstring);
+    connection_printf_to_buf(conn, "%s: %s\r\n", msg, errstring);
+    config_free_lines(lines);
+    tor_free(errstring);
+    return 0;
+  }
+}
+
+/** Return true iff <b>addr</b> is unusable as a mapaddress target because of
+ * containing funny characters. */
+static int
+address_is_invalid_mapaddress_target(const char *addr)
+{
+  if (!strcmpstart(addr, "*."))
+    return address_is_invalid_destination(addr+2, 1);
+  else
+    return address_is_invalid_destination(addr, 1);
+}
+
+/** Called when we get a MAPADDRESS command; try to bind all listed addresses,
+ * and report success or failure. */
+static int
+handle_control_mapaddress(control_connection_t *conn, uint32_t len,
+                          const char *body)
+{
+  smartlist_t *elts;
+  smartlist_t *lines;
+  smartlist_t *reply;
+  char *r;
+  size_t sz;
+  (void) len; /* body is NUL-terminated, so it's safe to ignore the length. */
+
+  lines = smartlist_new();
+  elts = smartlist_new();
+  reply = smartlist_new();
+  smartlist_split_string(lines, body, " ",
+                         SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, 0);
+  SMARTLIST_FOREACH_BEGIN(lines, char *, line) {
+    tor_strlower(line);
+    smartlist_split_string(elts, line, "=", 0, 2);
+    if (smartlist_len(elts) == 2) {
+      const char *from = smartlist_get(elts,0);
+      const char *to = smartlist_get(elts,1);
+      if (address_is_invalid_mapaddress_target(to)) {
+        smartlist_add_asprintf(reply,
+                     "512-syntax error: invalid address '%s'", to);
+        log_warn(LD_CONTROL,
+                 "Skipping invalid argument '%s' in MapAddress msg", to);
+      } else if (!strcmp(from, ".") || !strcmp(from, "0.0.0.0") ||
+                 !strcmp(from, "::")) {
+        const char type =
+          !strcmp(from,".") ? RESOLVED_TYPE_HOSTNAME :
+          (!strcmp(from, "0.0.0.0") ? RESOLVED_TYPE_IPV4 : RESOLVED_TYPE_IPV6);
+        const char *address = addressmap_register_virtual_address(
+                                                     type, tor_strdup(to));
+        if (!address) {
+          smartlist_add_asprintf(reply,
+                       "451-resource exhausted: skipping '%s'", line);
+          log_warn(LD_CONTROL,
+                   "Unable to allocate address for '%s' in MapAddress msg",
+                   safe_str_client(line));
+        } else {
+          smartlist_add_asprintf(reply, "250-%s=%s", address, to);
+        }
+      } else {
+        const char *msg;
+        if (addressmap_register_auto(from, to, 1,
+                                     ADDRMAPSRC_CONTROLLER, &msg) < 0) {
+          smartlist_add_asprintf(reply,
+                                 "512-syntax error: invalid address mapping "
+                                 " '%s': %s", line, msg);
+          log_warn(LD_CONTROL,
+                   "Skipping invalid argument '%s' in MapAddress msg: %s",
+                   line, msg);
+        } else {
+          smartlist_add_asprintf(reply, "250-%s", line);
+        }
+      }
+    } else {
+      smartlist_add_asprintf(reply, "512-syntax error: mapping '%s' is "
+                   "not of expected form 'foo=bar'.", line);
+      log_info(LD_CONTROL, "Skipping MapAddress '%s': wrong "
+                           "number of items.",
+                           safe_str_client(line));
+    }
+    SMARTLIST_FOREACH(elts, char *, cp, tor_free(cp));
+    smartlist_clear(elts);
+  } SMARTLIST_FOREACH_END(line);
+  SMARTLIST_FOREACH(lines, char *, cp, tor_free(cp));
+  smartlist_free(lines);
+  smartlist_free(elts);
+
+  if (smartlist_len(reply)) {
+    ((char*)smartlist_get(reply,smartlist_len(reply)-1))[3] = ' ';
+    r = smartlist_join_strings(reply, "\r\n", 1, &sz);
+    connection_buf_add(r, sz, TO_CONN(conn));
+    tor_free(r);
+  } else {
+    const char *response =
+      "512 syntax error: not enough arguments to mapaddress.\r\n";
+    connection_buf_add(response, strlen(response), TO_CONN(conn));
+  }
+
+  SMARTLIST_FOREACH(reply, char *, cp, tor_free(cp));
+  smartlist_free(reply);
+  return 0;
+}
+
+/** Given a string, convert it to a circuit purpose. */
+static uint8_t
+circuit_purpose_from_string(const char *string)
+{
+  if (!strcasecmpstart(string, "purpose="))
+    string += strlen("purpose=");
+
+  if (!strcasecmp(string, "general"))
+    return CIRCUIT_PURPOSE_C_GENERAL;
+  else if (!strcasecmp(string, "controller"))
+    return CIRCUIT_PURPOSE_CONTROLLER;
+  else
+    return CIRCUIT_PURPOSE_UNKNOWN;
+}
+
+/** Return a newly allocated smartlist containing the arguments to the command
+ * waiting in <b>body</b>. If there are fewer than <b>min_args</b> arguments,
+ * or if <b>max_args</b> is nonnegative and there are more than
+ * <b>max_args</b> arguments, send a 512 error to the controller, using
+ * <b>command</b> as the command name in the error message. */
+static smartlist_t *
+getargs_helper(const char *command, control_connection_t *conn,
+               const char *body, int min_args, int max_args)
+{
+  smartlist_t *args = smartlist_new();
+  smartlist_split_string(args, body, " ",
+                         SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, 0);
+  if (smartlist_len(args) < min_args) {
+    connection_printf_to_buf(conn, "512 Missing argument to %s\r\n",command);
+    goto err;
+  } else if (max_args >= 0 && smartlist_len(args) > max_args) {
+    connection_printf_to_buf(conn, "512 Too many arguments to %s\r\n",command);
+    goto err;
+  }
+  return args;
+ err:
+  SMARTLIST_FOREACH(args, char *, s, tor_free(s));
+  smartlist_free(args);
+  return NULL;
+}
+
+/** Helper.  Return the first element of <b>sl</b> at index <b>start_at</b> or
+ * higher that starts with <b>prefix</b>, case-insensitive.  Return NULL if no
+ * such element exists. */
+static const char *
+find_element_starting_with(smartlist_t *sl, int start_at, const char *prefix)
+{
+  int i;
+  for (i = start_at; i < smartlist_len(sl); ++i) {
+    const char *elt = smartlist_get(sl, i);
+    if (!strcasecmpstart(elt, prefix))
+      return elt;
+  }
+  return NULL;
+}
+
+/** Helper.  Return true iff s is an argument that we should treat as a
+ * key-value pair. */
+static int
+is_keyval_pair(const char *s)
+{
+  /* An argument is a key-value pair if it has an =, and it isn't of the form
+   * $fingeprint=name */
+  return strchr(s, '=') && s[0] != '$';
+}
+
+/** Called when we get an EXTENDCIRCUIT message.  Try to extend the listed
+ * circuit, and report success or failure. */
+static int
+handle_control_extendcircuit(control_connection_t *conn, uint32_t len,
+                             const char *body)
+{
+  smartlist_t *router_nicknames=NULL, *nodes=NULL;
+  origin_circuit_t *circ = NULL;
+  int zero_circ;
+  uint8_t intended_purpose = CIRCUIT_PURPOSE_C_GENERAL;
+  smartlist_t *args;
+  (void) len;
+
+  router_nicknames = smartlist_new();
+
+  args = getargs_helper("EXTENDCIRCUIT", conn, body, 1, -1);
+  if (!args)
+    goto done;
+
+  zero_circ = !strcmp("0", (char*)smartlist_get(args,0));
+
+  if (zero_circ) {
+    const char *purp = find_element_starting_with(args, 1, "PURPOSE=");
+
+    if (purp) {
+      intended_purpose = circuit_purpose_from_string(purp);
+      if (intended_purpose == CIRCUIT_PURPOSE_UNKNOWN) {
+        connection_printf_to_buf(conn, "552 Unknown purpose \"%s\"\r\n", purp);
+        SMARTLIST_FOREACH(args, char *, cp, tor_free(cp));
+        smartlist_free(args);
+        goto done;
+      }
+    }
+
+    if ((smartlist_len(args) == 1) ||
+        (smartlist_len(args) >= 2 && is_keyval_pair(smartlist_get(args, 1)))) {
+      // "EXTENDCIRCUIT 0" || EXTENDCIRCUIT 0 foo=bar"
+      circ = circuit_launch(intended_purpose, CIRCLAUNCH_NEED_CAPACITY);
+      if (!circ) {
+        connection_write_str_to_buf("551 Couldn't start circuit\r\n", conn);
+      } else {
+        connection_printf_to_buf(conn, "250 EXTENDED %lu\r\n",
+                  (unsigned long)circ->global_identifier);
+      }
+      SMARTLIST_FOREACH(args, char *, cp, tor_free(cp));
+      smartlist_free(args);
+      goto done;
+    }
+    // "EXTENDCIRCUIT 0 router1,router2" ||
+    // "EXTENDCIRCUIT 0 router1,router2 PURPOSE=foo"
+  }
+
+  if (!zero_circ && !(circ = get_circ(smartlist_get(args,0)))) {
+    connection_printf_to_buf(conn, "552 Unknown circuit \"%s\"\r\n",
+                             (char*)smartlist_get(args, 0));
+    SMARTLIST_FOREACH(args, char *, cp, tor_free(cp));
+    smartlist_free(args);
+    goto done;
+  }
+
+  if (smartlist_len(args) < 2) {
+    connection_printf_to_buf(conn,
+                             "512 syntax error: not enough arguments.\r\n");
+    SMARTLIST_FOREACH(args, char *, cp, tor_free(cp));
+    smartlist_free(args);
+    goto done;
+  }
+
+  smartlist_split_string(router_nicknames, smartlist_get(args,1), ",", 0, 0);
+
+  SMARTLIST_FOREACH(args, char *, cp, tor_free(cp));
+  smartlist_free(args);
+
+  nodes = smartlist_new();
+  int first_node = zero_circ;
+  SMARTLIST_FOREACH_BEGIN(router_nicknames, const char *, n) {
+    const node_t *node = node_get_by_nickname(n, 0);
+    if (!node) {
+      connection_printf_to_buf(conn, "552 No such router \"%s\"\r\n", n);
+      goto done;
+    }
+    if (!node_has_preferred_descriptor(node, first_node)) {
+      connection_printf_to_buf(conn, "552 No descriptor for \"%s\"\r\n", n);
+      goto done;
+    }
+    smartlist_add(nodes, (void*)node);
+    first_node = 0;
+  } SMARTLIST_FOREACH_END(n);
+  if (!smartlist_len(nodes)) {
+    connection_write_str_to_buf("512 No router names provided\r\n", conn);
+    goto done;
+  }
+
+  if (zero_circ) {
+    /* start a new circuit */
+    circ = origin_circuit_init(intended_purpose, 0);
+  }
+
+  /* now circ refers to something that is ready to be extended */
+  first_node = zero_circ;
+  SMARTLIST_FOREACH(nodes, const node_t *, node,
+  {
+    extend_info_t *info = extend_info_from_node(node, first_node);
+    if (!info) {
+      tor_assert_nonfatal(first_node);
+      log_warn(LD_CONTROL,
+               "controller tried to connect to a node that lacks a suitable "
+               "descriptor, or which doesn't have any "
+               "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);
+      goto done;
+    }
+    circuit_append_new_exit(circ, info);
+    if (circ->build_state->desired_path_len > 1) {
+      circ->build_state->onehop_tunnel = 0;
+    }
+    extend_info_free(info);
+    first_node = 0;
+  });
+
+  /* now that we've populated the cpath, start extending */
+  if (zero_circ) {
+    int err_reason = 0;
+    if ((err_reason = circuit_handle_first_hop(circ)) < 0) {
+      circuit_mark_for_close(TO_CIRCUIT(circ), -err_reason);
+      connection_write_str_to_buf("551 Couldn't start circuit\r\n", conn);
+      goto done;
+    }
+  } else {
+    if (circ->base_.state == CIRCUIT_STATE_OPEN ||
+        circ->base_.state == CIRCUIT_STATE_GUARD_WAIT) {
+      int err_reason = 0;
+      circuit_set_state(TO_CIRCUIT(circ), CIRCUIT_STATE_BUILDING);
+      if ((err_reason = circuit_send_next_onion_skin(circ)) < 0) {
+        log_info(LD_CONTROL,
+                 "send_next_onion_skin failed; circuit marked for closing.");
+        circuit_mark_for_close(TO_CIRCUIT(circ), -err_reason);
+        connection_write_str_to_buf("551 Couldn't send onion skin\r\n", conn);
+        goto done;
+      }
+    }
+  }
+
+  connection_printf_to_buf(conn, "250 EXTENDED %lu\r\n",
+                             (unsigned long)circ->global_identifier);
+  if (zero_circ) /* send a 'launched' event, for completeness */
+    circuit_event_status(circ, CIRC_EVENT_LAUNCHED, 0);
+ done:
+  SMARTLIST_FOREACH(router_nicknames, char *, n, tor_free(n));
+  smartlist_free(router_nicknames);
+  smartlist_free(nodes);
+  return 0;
+}
+
+/** Called when we get a SETCIRCUITPURPOSE message. If we can find the
+ * circuit and it's a valid purpose, change it. */
+static int
+handle_control_setcircuitpurpose(control_connection_t *conn,
+                                 uint32_t len, const char *body)
+{
+  origin_circuit_t *circ = NULL;
+  uint8_t new_purpose;
+  smartlist_t *args;
+  (void) len; /* body is NUL-terminated, so it's safe to ignore the length. */
+
+  args = getargs_helper("SETCIRCUITPURPOSE", conn, body, 2, -1);
+  if (!args)
+    goto done;
+
+  if (!(circ = get_circ(smartlist_get(args,0)))) {
+    connection_printf_to_buf(conn, "552 Unknown circuit \"%s\"\r\n",
+                             (char*)smartlist_get(args, 0));
+    goto done;
+  }
+
+  {
+    const char *purp = find_element_starting_with(args,1,"PURPOSE=");
+    if (!purp) {
+      connection_write_str_to_buf("552 No purpose given\r\n", conn);
+      goto done;
+    }
+    new_purpose = circuit_purpose_from_string(purp);
+    if (new_purpose == CIRCUIT_PURPOSE_UNKNOWN) {
+      connection_printf_to_buf(conn, "552 Unknown purpose \"%s\"\r\n", purp);
+      goto done;
+    }
+  }
+
+  circuit_change_purpose(TO_CIRCUIT(circ), new_purpose);
+  connection_write_str_to_buf("250 OK\r\n", conn);
+
+ done:
+  if (args) {
+    SMARTLIST_FOREACH(args, char *, cp, tor_free(cp));
+    smartlist_free(args);
+  }
+  return 0;
+}
+
+/** Called when we get an ATTACHSTREAM message.  Try to attach the requested
+ * stream, and report success or failure. */
+static int
+handle_control_attachstream(control_connection_t *conn, uint32_t len,
+                            const char *body)
+{
+  entry_connection_t *ap_conn = NULL;
+  origin_circuit_t *circ = NULL;
+  int zero_circ;
+  smartlist_t *args;
+  crypt_path_t *cpath=NULL;
+  int hop=0, hop_line_ok=1;
+  (void) len;
+
+  args = getargs_helper("ATTACHSTREAM", conn, body, 2, -1);
+  if (!args)
+    return 0;
+
+  zero_circ = !strcmp("0", (char*)smartlist_get(args,1));
+
+  if (!(ap_conn = get_stream(smartlist_get(args, 0)))) {
+    connection_printf_to_buf(conn, "552 Unknown stream \"%s\"\r\n",
+                             (char*)smartlist_get(args, 0));
+  } else if (!zero_circ && !(circ = get_circ(smartlist_get(args, 1)))) {
+    connection_printf_to_buf(conn, "552 Unknown circuit \"%s\"\r\n",
+                             (char*)smartlist_get(args, 1));
+  } else if (circ) {
+    const char *hopstring = find_element_starting_with(args,2,"HOP=");
+    if (hopstring) {
+      hopstring += strlen("HOP=");
+      hop = (int) tor_parse_ulong(hopstring, 10, 0, INT_MAX,
+                                  &hop_line_ok, NULL);
+      if (!hop_line_ok) { /* broken hop line */
+        connection_printf_to_buf(conn, "552 Bad value hop=%s\r\n", hopstring);
+      }
+    }
+  }
+  SMARTLIST_FOREACH(args, char *, cp, tor_free(cp));
+  smartlist_free(args);
+  if (!ap_conn || (!zero_circ && !circ) || !hop_line_ok)
+    return 0;
+
+  if (ENTRY_TO_CONN(ap_conn)->state != AP_CONN_STATE_CONTROLLER_WAIT &&
+      ENTRY_TO_CONN(ap_conn)->state != AP_CONN_STATE_CONNECT_WAIT &&
+      ENTRY_TO_CONN(ap_conn)->state != AP_CONN_STATE_RESOLVE_WAIT) {
+    connection_write_str_to_buf(
+                    "555 Connection is not managed by controller.\r\n",
+                    conn);
+    return 0;
+  }
+
+  /* Do we need to detach it first? */
+  if (ENTRY_TO_CONN(ap_conn)->state != AP_CONN_STATE_CONTROLLER_WAIT) {
+    edge_connection_t *edge_conn = ENTRY_TO_EDGE_CONN(ap_conn);
+    circuit_t *tmpcirc = circuit_get_by_edge_conn(edge_conn);
+    connection_edge_end(edge_conn, END_STREAM_REASON_TIMEOUT);
+    /* Un-mark it as ending, since we're going to reuse it. */
+    edge_conn->edge_has_sent_end = 0;
+    edge_conn->end_reason = 0;
+    if (tmpcirc)
+      circuit_detach_stream(tmpcirc, edge_conn);
+    CONNECTION_AP_EXPECT_NONPENDING(ap_conn);
+    TO_CONN(edge_conn)->state = AP_CONN_STATE_CONTROLLER_WAIT;
+  }
+
+  if (circ && (circ->base_.state != CIRCUIT_STATE_OPEN)) {
+    connection_write_str_to_buf(
+                    "551 Can't attach stream to non-open origin circuit\r\n",
+                    conn);
+    return 0;
+  }
+  /* Is this a single hop circuit? */
+  if (circ && (circuit_get_cpath_len(circ)<2 || hop==1)) {
+    connection_write_str_to_buf(
+               "551 Can't attach stream to this one-hop circuit.\r\n", conn);
+    return 0;
+  }
+
+  if (circ && hop>0) {
+    /* find this hop in the circuit, and set cpath */
+    cpath = circuit_get_cpath_hop(circ, hop);
+    if (!cpath) {
+      connection_printf_to_buf(conn,
+                               "551 Circuit doesn't have %d hops.\r\n", hop);
+      return 0;
+    }
+  }
+  if (connection_ap_handshake_rewrite_and_attach(ap_conn, circ, cpath) < 0) {
+    connection_write_str_to_buf("551 Unable to attach stream\r\n", conn);
+    return 0;
+  }
+  send_control_done(conn);
+  return 0;
+}
+
+/** Called when we get a POSTDESCRIPTOR message.  Try to learn the provided
+ * descriptor, and report success or failure. */
+static int
+handle_control_postdescriptor(control_connection_t *conn, uint32_t len,
+                              const char *body)
+{
+  char *desc;
+  const char *msg=NULL;
+  uint8_t purpose = ROUTER_PURPOSE_GENERAL;
+  int cache = 0; /* eventually, we may switch this to 1 */
+
+  const char *cp = memchr(body, '\n', len);
+
+  if (cp == NULL) {
+    connection_printf_to_buf(conn, "251 Empty body\r\n");
+    return 0;
+  }
+  ++cp;
+
+  char *cmdline = tor_memdup_nulterm(body, cp-body);
+  smartlist_t *args = smartlist_new();
+  smartlist_split_string(args, cmdline, " ",
+                         SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, 0);
+  SMARTLIST_FOREACH_BEGIN(args, char *, option) {
+    if (!strcasecmpstart(option, "purpose=")) {
+      option += strlen("purpose=");
+      purpose = router_purpose_from_string(option);
+      if (purpose == ROUTER_PURPOSE_UNKNOWN) {
+        connection_printf_to_buf(conn, "552 Unknown purpose \"%s\"\r\n",
+                                 option);
+        goto done;
+      }
+    } else if (!strcasecmpstart(option, "cache=")) {
+      option += strlen("cache=");
+      if (!strcasecmp(option, "no"))
+        cache = 0;
+      else if (!strcasecmp(option, "yes"))
+        cache = 1;
+      else {
+        connection_printf_to_buf(conn, "552 Unknown cache request \"%s\"\r\n",
+                                 option);
+        goto done;
+      }
+    } else { /* unrecognized argument? */
+      connection_printf_to_buf(conn,
+        "512 Unexpected argument \"%s\" to postdescriptor\r\n", option);
+      goto done;
+    }
+  } SMARTLIST_FOREACH_END(option);
+
+  read_escaped_data(cp, len-(cp-body), &desc);
+
+  switch (router_load_single_router(desc, purpose, cache, &msg)) {
+  case -1:
+    if (!msg) msg = "Could not parse descriptor";
+    connection_printf_to_buf(conn, "554 %s\r\n", msg);
+    break;
+  case 0:
+    if (!msg) msg = "Descriptor not added";
+    connection_printf_to_buf(conn, "251 %s\r\n",msg);
+    break;
+  case 1:
+    send_control_done(conn);
+    break;
+  }
+
+  tor_free(desc);
+ done:
+  SMARTLIST_FOREACH(args, char *, arg, tor_free(arg));
+  smartlist_free(args);
+  tor_free(cmdline);
+  return 0;
+}
+
+/** Called when we receive a REDIRECTSTERAM command.  Try to change the target
+ * address of the named AP stream, and report success or failure. */
+static int
+handle_control_redirectstream(control_connection_t *conn, uint32_t len,
+                              const char *body)
+{
+  entry_connection_t *ap_conn = NULL;
+  char *new_addr = NULL;
+  uint16_t new_port = 0;
+  smartlist_t *args;
+  (void) len;
+
+  args = getargs_helper("REDIRECTSTREAM", conn, body, 2, -1);
+  if (!args)
+    return 0;
+
+  if (!(ap_conn = get_stream(smartlist_get(args, 0)))
+           || !ap_conn->socks_request) {
+    connection_printf_to_buf(conn, "552 Unknown stream \"%s\"\r\n",
+                             (char*)smartlist_get(args, 0));
+  } else {
+    int ok = 1;
+    if (smartlist_len(args) > 2) { /* they included a port too */
+      new_port = (uint16_t) tor_parse_ulong(smartlist_get(args, 2),
+                                            10, 1, 65535, &ok, NULL);
+    }
+    if (!ok) {
+      connection_printf_to_buf(conn, "512 Cannot parse port \"%s\"\r\n",
+                               (char*)smartlist_get(args, 2));
+    } else {
+      new_addr = tor_strdup(smartlist_get(args, 1));
+    }
+  }
+
+  SMARTLIST_FOREACH(args, char *, cp, tor_free(cp));
+  smartlist_free(args);
+  if (!new_addr)
+    return 0;
+
+  strlcpy(ap_conn->socks_request->address, new_addr,
+          sizeof(ap_conn->socks_request->address));
+  if (new_port)
+    ap_conn->socks_request->port = new_port;
+  tor_free(new_addr);
+  send_control_done(conn);
+  return 0;
+}
+
+/** Called when we get a CLOSESTREAM command; try to close the named stream
+ * and report success or failure. */
+static int
+handle_control_closestream(control_connection_t *conn, uint32_t len,
+                           const char *body)
+{
+  entry_connection_t *ap_conn=NULL;
+  uint8_t reason=0;
+  smartlist_t *args;
+  int ok;
+  (void) len;
+
+  args = getargs_helper("CLOSESTREAM", conn, body, 2, -1);
+  if (!args)
+    return 0;
+
+  else if (!(ap_conn = get_stream(smartlist_get(args, 0))))
+    connection_printf_to_buf(conn, "552 Unknown stream \"%s\"\r\n",
+                             (char*)smartlist_get(args, 0));
+  else {
+    reason = (uint8_t) tor_parse_ulong(smartlist_get(args,1), 10, 0, 255,
+                                       &ok, NULL);
+    if (!ok) {
+      connection_printf_to_buf(conn, "552 Unrecognized reason \"%s\"\r\n",
+                               (char*)smartlist_get(args, 1));
+      ap_conn = NULL;
+    }
+  }
+  SMARTLIST_FOREACH(args, char *, cp, tor_free(cp));
+  smartlist_free(args);
+  if (!ap_conn)
+    return 0;
+
+  connection_mark_unattached_ap(ap_conn, reason);
+  send_control_done(conn);
+  return 0;
+}
+
+/** Called when we get a CLOSECIRCUIT command; try to close the named circuit
+ * and report success or failure. */
+static int
+handle_control_closecircuit(control_connection_t *conn, uint32_t len,
+                            const char *body)
+{
+  origin_circuit_t *circ = NULL;
+  int safe = 0;
+  smartlist_t *args;
+  (void) len;
+
+  args = getargs_helper("CLOSECIRCUIT", conn, body, 1, -1);
+  if (!args)
+    return 0;
+
+  if (!(circ=get_circ(smartlist_get(args, 0))))
+    connection_printf_to_buf(conn, "552 Unknown circuit \"%s\"\r\n",
+                             (char*)smartlist_get(args, 0));
+  else {
+    int i;
+    for (i=1; i < smartlist_len(args); ++i) {
+      if (!strcasecmp(smartlist_get(args, i), "IfUnused"))
+        safe = 1;
+      else
+        log_info(LD_CONTROL, "Skipping unknown option %s",
+                 (char*)smartlist_get(args,i));
+    }
+  }
+  SMARTLIST_FOREACH(args, char *, cp, tor_free(cp));
+  smartlist_free(args);
+  if (!circ)
+    return 0;
+
+  if (!safe || !circ->p_streams) {
+    circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_REQUESTED);
+  }
+
+  send_control_done(conn);
+  return 0;
+}
+
+/** Called when we get a RESOLVE command: start trying to resolve
+ * the listed addresses. */
+static int
+handle_control_resolve(control_connection_t *conn, uint32_t len,
+                       const char *body)
+{
+  smartlist_t *args, *failed;
+  int is_reverse = 0;
+  (void) len; /* body is nul-terminated; it's safe to ignore the length */
+
+  if (!(conn->event_mask & (((event_mask_t)1)<<EVENT_ADDRMAP))) {
+    log_warn(LD_CONTROL, "Controller asked us to resolve an address, but "
+             "isn't listening for ADDRMAP events.  It probably won't see "
+             "the answer.");
+  }
+  args = smartlist_new();
+  smartlist_split_string(args, body, " ",
+                         SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, 0);
+  {
+    const char *modearg = find_element_starting_with(args, 0, "mode=");
+    if (modearg && !strcasecmp(modearg, "mode=reverse"))
+      is_reverse = 1;
+  }
+  failed = smartlist_new();
+  SMARTLIST_FOREACH(args, const char *, arg, {
+      if (!is_keyval_pair(arg)) {
+          if (dnsserv_launch_request(arg, is_reverse, conn)<0)
+            smartlist_add(failed, (char*)arg);
+      }
+  });
+
+  send_control_done(conn);
+  SMARTLIST_FOREACH(failed, const char *, arg, {
+      control_event_address_mapped(arg, arg, time(NULL),
+                                   "internal", 0);
+  });
+
+  SMARTLIST_FOREACH(args, char *, cp, tor_free(cp));
+  smartlist_free(args);
+  smartlist_free(failed);
+  return 0;
+}
+
+/** Called when we get a PROTOCOLINFO command: send back a reply. */
+static int
+handle_control_protocolinfo(control_connection_t *conn, uint32_t len,
+                            const char *body)
+{
+  const char *bad_arg = NULL;
+  smartlist_t *args;
+  (void)len;
+
+  conn->have_sent_protocolinfo = 1;
+  args = smartlist_new();
+  smartlist_split_string(args, body, " ",
+                         SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, 0);
+  SMARTLIST_FOREACH(args, const char *, arg, {
+      int ok;
+      tor_parse_long(arg, 10, 0, LONG_MAX, &ok, NULL);
+      if (!ok) {
+        bad_arg = arg;
+        break;
+      }
+    });
+  if (bad_arg) {
+    connection_printf_to_buf(conn, "513 No such version %s\r\n",
+                             escaped(bad_arg));
+    /* Don't tolerate bad arguments when not authenticated. */
+    if (!STATE_IS_OPEN(TO_CONN(conn)->state))
+      connection_mark_for_close(TO_CONN(conn));
+    goto done;
+  } else {
+    const or_options_t *options = get_options();
+    int cookies = options->CookieAuthentication;
+    char *cfile = get_controller_cookie_file_name();
+    char *abs_cfile;
+    char *esc_cfile;
+    char *methods;
+    abs_cfile = make_path_absolute(cfile);
+    esc_cfile = esc_for_log(abs_cfile);
+    {
+      int passwd = (options->HashedControlPassword != NULL ||
+                    options->HashedControlSessionPassword != NULL);
+      smartlist_t *mlist = smartlist_new();
+      if (cookies) {
+        smartlist_add(mlist, (char*)"COOKIE");
+        smartlist_add(mlist, (char*)"SAFECOOKIE");
+      }
+      if (passwd)
+        smartlist_add(mlist, (char*)"HASHEDPASSWORD");
+      if (!cookies && !passwd)
+        smartlist_add(mlist, (char*)"NULL");
+      methods = smartlist_join_strings(mlist, ",", 0, NULL);
+      smartlist_free(mlist);
+    }
+
+    connection_printf_to_buf(conn,
+                             "250-PROTOCOLINFO 1\r\n"
+                             "250-AUTH METHODS=%s%s%s\r\n"
+                             "250-VERSION Tor=%s\r\n"
+                             "250 OK\r\n",
+                             methods,
+                             cookies?" COOKIEFILE=":"",
+                             cookies?esc_cfile:"",
+                             escaped(VERSION));
+    tor_free(methods);
+    tor_free(cfile);
+    tor_free(abs_cfile);
+    tor_free(esc_cfile);
+  }
+ done:
+  SMARTLIST_FOREACH(args, char *, cp, tor_free(cp));
+  smartlist_free(args);
+  return 0;
+}
+
+/** Called when we get a USEFEATURE command: parse the feature list, and
+ * set up the control_connection's options properly. */
+static int
+handle_control_usefeature(control_connection_t *conn,
+                          uint32_t len,
+                          const char *body)
+{
+  smartlist_t *args;
+  int bad = 0;
+  (void) len; /* body is nul-terminated; it's safe to ignore the length */
+  args = smartlist_new();
+  smartlist_split_string(args, body, " ",
+                         SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, 0);
+  SMARTLIST_FOREACH_BEGIN(args, const char *, arg) {
+      if (!strcasecmp(arg, "VERBOSE_NAMES"))
+        ;
+      else if (!strcasecmp(arg, "EXTENDED_EVENTS"))
+        ;
+      else {
+        connection_printf_to_buf(conn, "552 Unrecognized feature \"%s\"\r\n",
+                                 arg);
+        bad = 1;
+        break;
+      }
+  } SMARTLIST_FOREACH_END(arg);
+
+  if (!bad) {
+    send_control_done(conn);
+  }
+
+  SMARTLIST_FOREACH(args, char *, cp, tor_free(cp));
+  smartlist_free(args);
+  return 0;
+}
+
+/** Implementation for the DROPGUARDS command. */
+static int
+handle_control_dropguards(control_connection_t *conn,
+                          uint32_t len,
+                          const char *body)
+{
+  smartlist_t *args;
+  (void) len; /* body is nul-terminated; it's safe to ignore the length */
+  args = smartlist_new();
+  smartlist_split_string(args, body, " ",
+                         SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, 0);
+
+  static int have_warned = 0;
+  if (! have_warned) {
+    log_warn(LD_CONTROL, "DROPGUARDS is dangerous; make sure you understand "
+             "the risks before using it. It may be removed in a future "
+             "version of Tor.");
+    have_warned = 1;
+  }
+
+  if (smartlist_len(args)) {
+    connection_printf_to_buf(conn, "512 Too many arguments to DROPGUARDS\r\n");
+  } else {
+    remove_all_entry_guards();
+    send_control_done(conn);
+  }
+
+  SMARTLIST_FOREACH(args, char *, cp, tor_free(cp));
+  smartlist_free(args);
+  return 0;
+}
+
+/** Implementation for the HSFETCH command. */
+static int
+handle_control_hsfetch(control_connection_t *conn, uint32_t len,
+                       const char *body)
+{
+  int i;
+  char digest[DIGEST_LEN], *hsaddress = NULL, *arg1 = NULL, *desc_id = NULL;
+  smartlist_t *args = NULL, *hsdirs = NULL;
+  (void) len; /* body is nul-terminated; it's safe to ignore the length */
+  static const char *hsfetch_command = "HSFETCH";
+  static const char *v2_str = "v2-";
+  const size_t v2_str_len = strlen(v2_str);
+  rend_data_t *rend_query = NULL;
+  ed25519_public_key_t v3_pk;
+  uint32_t version;
+
+  /* Make sure we have at least one argument, the HSAddress. */
+  args = getargs_helper(hsfetch_command, conn, body, 1, -1);
+  if (!args) {
+    goto exit;
+  }
+
+  /* Extract the first argument (either HSAddress or DescID). */
+  arg1 = smartlist_get(args, 0);
+  /* Test if it's an HS address without the .onion part. */
+  if (rend_valid_v2_service_id(arg1)) {
+    hsaddress = arg1;
+    version = HS_VERSION_TWO;
+  } else if (strcmpstart(arg1, v2_str) == 0 &&
+             rend_valid_descriptor_id(arg1 + v2_str_len) &&
+             base32_decode(digest, sizeof(digest), arg1 + v2_str_len,
+                           REND_DESC_ID_V2_LEN_BASE32) ==
+                REND_DESC_ID_V2_LEN_BASE32) {
+    /* We have a well formed version 2 descriptor ID. Keep the decoded value
+     * of the id. */
+    desc_id = digest;
+    version = HS_VERSION_TWO;
+  } else if (hs_address_is_valid(arg1)) {
+    hsaddress = arg1;
+    version = HS_VERSION_THREE;
+    hs_parse_address(hsaddress, &v3_pk, NULL, NULL);
+  } else {
+    connection_printf_to_buf(conn, "513 Invalid argument \"%s\"\r\n",
+                             arg1);
+    goto done;
+  }
+
+  static const char *opt_server = "SERVER=";
+
+  /* Skip first argument because it's the HSAddress or DescID. */
+  for (i = 1; i < smartlist_len(args); ++i) {
+    const char *arg = smartlist_get(args, i);
+    const node_t *node;
+
+    if (!strcasecmpstart(arg, opt_server)) {
+      const char *server;
+
+      server = arg + strlen(opt_server);
+      node = node_get_by_hex_id(server, 0);
+      if (!node) {
+        connection_printf_to_buf(conn, "552 Server \"%s\" not found\r\n",
+                                 server);
+        goto done;
+      }
+      if (!hsdirs) {
+        /* Stores routerstatus_t object for each specified server. */
+        hsdirs = smartlist_new();
+      }
+      /* Valid server, add it to our local list. */
+      smartlist_add(hsdirs, node->rs);
+    } else {
+      connection_printf_to_buf(conn, "513 Unexpected argument \"%s\"\r\n",
+                               arg);
+      goto done;
+    }
+  }
+
+  if (version == HS_VERSION_TWO) {
+    rend_query = rend_data_client_create(hsaddress, desc_id, NULL,
+                                         REND_NO_AUTH);
+    if (rend_query == NULL) {
+      connection_printf_to_buf(conn, "551 Error creating the HS query\r\n");
+      goto done;
+    }
+  }
+
+  /* Using a descriptor ID, we force the user to provide at least one
+   * hsdir server using the SERVER= option. */
+  if (desc_id && (!hsdirs || !smartlist_len(hsdirs))) {
+      connection_printf_to_buf(conn, "512 %s option is required\r\n",
+                               opt_server);
+      goto done;
+  }
+
+  /* We are about to trigger HSDir fetch so send the OK now because after
+   * that 650 event(s) are possible so better to have the 250 OK before them
+   * to avoid out of order replies. */
+  send_control_done(conn);
+
+  /* Trigger the fetch using the built rend query and possibly a list of HS
+   * directory to use. This function ignores the client cache thus this will
+   * always send a fetch command. */
+  if (version == HS_VERSION_TWO) {
+    rend_client_fetch_v2_desc(rend_query, hsdirs);
+  } else if (version == HS_VERSION_THREE) {
+    hs_control_hsfetch_command(&v3_pk, hsdirs);
+  }
+
+ done:
+  SMARTLIST_FOREACH(args, char *, cp, tor_free(cp));
+  smartlist_free(args);
+  /* Contains data pointer that we don't own thus no cleanup. */
+  smartlist_free(hsdirs);
+  rend_data_free(rend_query);
+ exit:
+  return 0;
+}
+
+/** Implementation for the HSPOST command. */
+static int
+handle_control_hspost(control_connection_t *conn,
+                      uint32_t len,
+                      const char *body)
+{
+  static const char *opt_server = "SERVER=";
+  static const char *opt_hsaddress = "HSADDRESS=";
+  smartlist_t *hs_dirs = NULL;
+  const char *encoded_desc = body;
+  size_t encoded_desc_len = len;
+  const char *onion_address = NULL;
+
+  char *cp = memchr(body, '\n', len);
+  if (cp == NULL) {
+    connection_printf_to_buf(conn, "251 Empty body\r\n");
+    return 0;
+  }
+  char *argline = tor_strndup(body, cp-body);
+
+  smartlist_t *args = smartlist_new();
+
+  /* If any SERVER= or HSADDRESS= options were specified, try to parse
+   * the options line. */
+  if (!strcasecmpstart(argline, opt_server) ||
+      !strcasecmpstart(argline, opt_hsaddress)) {
+    /* encoded_desc begins after a newline character */
+    cp = cp + 1;
+    encoded_desc = cp;
+    encoded_desc_len = len-(cp-body);
+
+    smartlist_split_string(args, argline, " ",
+                           SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, 0);
+    SMARTLIST_FOREACH_BEGIN(args, const char *, arg) {
+      if (!strcasecmpstart(arg, opt_server)) {
+        const char *server = arg + strlen(opt_server);
+        const node_t *node = node_get_by_hex_id(server, 0);
+
+        if (!node || !node->rs) {
+          connection_printf_to_buf(conn, "552 Server \"%s\" not found\r\n",
+                                   server);
+          goto done;
+        }
+        /* Valid server, add it to our local list. */
+        if (!hs_dirs)
+          hs_dirs = smartlist_new();
+        smartlist_add(hs_dirs, node->rs);
+      } else if (!strcasecmpstart(arg, opt_hsaddress)) {
+        const char *address = arg + strlen(opt_hsaddress);
+        if (!hs_address_is_valid(address)) {
+          connection_printf_to_buf(conn, "512 Malformed onion address\r\n");
+          goto done;
+        }
+        onion_address = address;
+      } else {
+        connection_printf_to_buf(conn, "512 Unexpected argument \"%s\"\r\n",
+                                 arg);
+        goto done;
+      }
+    } SMARTLIST_FOREACH_END(arg);
+  }
+
+  /* Handle the v3 case. */
+  if (onion_address) {
+    char *desc_str = NULL;
+    read_escaped_data(encoded_desc, encoded_desc_len, &desc_str);
+    if (hs_control_hspost_command(desc_str, onion_address, hs_dirs) < 0) {
+      connection_printf_to_buf(conn, "554 Invalid descriptor\r\n");
+    } else {
+      send_control_done(conn);
+    }
+    tor_free(desc_str);
+    goto done;
+  }
+
+  /* From this point on, it is only v2. */
+
+  /* Read the dot encoded descriptor, and parse it. */
+  rend_encoded_v2_service_descriptor_t *desc =
+      tor_malloc_zero(sizeof(rend_encoded_v2_service_descriptor_t));
+  read_escaped_data(encoded_desc, encoded_desc_len, &desc->desc_str);
+
+  rend_service_descriptor_t *parsed = NULL;
+  char *intro_content = NULL;
+  size_t intro_size;
+  size_t encoded_size;
+  const char *next_desc;
+  if (!rend_parse_v2_service_descriptor(&parsed, desc->desc_id, &intro_content,
+                                        &intro_size, &encoded_size,
+                                        &next_desc, desc->desc_str, 1)) {
+    /* Post the descriptor. */
+    char serviceid[REND_SERVICE_ID_LEN_BASE32+1];
+    if (!rend_get_service_id(parsed->pk, serviceid)) {
+      smartlist_t *descs = smartlist_new();
+      smartlist_add(descs, desc);
+
+      /* We are about to trigger HS descriptor upload so send the OK now
+       * because after that 650 event(s) are possible so better to have the
+       * 250 OK before them to avoid out of order replies. */
+      send_control_done(conn);
+
+      /* Trigger the descriptor upload */
+      directory_post_to_hs_dir(parsed, descs, hs_dirs, serviceid, 0);
+      smartlist_free(descs);
+    }
+
+    rend_service_descriptor_free(parsed);
+  } else {
+    connection_printf_to_buf(conn, "554 Invalid descriptor\r\n");
+  }
+
+  tor_free(intro_content);
+  rend_encoded_v2_service_descriptor_free(desc);
+ done:
+  tor_free(argline);
+  smartlist_free(hs_dirs); /* Contents belong to the rend service code. */
+  SMARTLIST_FOREACH(args, char *, arg, tor_free(arg));
+  smartlist_free(args);
+  return 0;
+}
+
+/* Helper function for ADD_ONION that adds an ephemeral service depending on
+ * the given hs_version.
+ *
+ * The secret key in pk depends on the hs_version. The ownership of the key
+ * used in pk is given to the HS subsystem so the caller must stop accessing
+ * it after.
+ *
+ * The port_cfgs is a list of service port. Ownership transferred to service.
+ * The max_streams refers to the MaxStreams= key.
+ * The max_streams_close_circuit refers to the MaxStreamsCloseCircuit key.
+ * The auth_type is the authentication type of the clients in auth_clients.
+ * The ownership of that list is transferred to the service.
+ *
+ * On success (RSAE_OKAY), the address_out points to a newly allocated string
+ * containing the onion address without the .onion part. On error, address_out
+ * is untouched. */
+static hs_service_add_ephemeral_status_t
+add_onion_helper_add_service(int hs_version,
+                             add_onion_secret_key_t *pk,
+                             smartlist_t *port_cfgs, int max_streams,
+                             int max_streams_close_circuit, int auth_type,
+                             smartlist_t *auth_clients, char **address_out)
+{
+  hs_service_add_ephemeral_status_t ret;
+
+  tor_assert(pk);
+  tor_assert(port_cfgs);
+  tor_assert(address_out);
+
+  switch (hs_version) {
+  case HS_VERSION_TWO:
+    ret = rend_service_add_ephemeral(pk->v2, port_cfgs, max_streams,
+                                     max_streams_close_circuit, auth_type,
+                                     auth_clients, address_out);
+    break;
+  case HS_VERSION_THREE:
+    ret = hs_service_add_ephemeral(pk->v3, port_cfgs, max_streams,
+                                   max_streams_close_circuit, address_out);
+    break;
+  default:
+    tor_assert_unreached();
+  }
+
+  return ret;
+}
+
+/** The list of onion services that have been added via ADD_ONION that do not
+ * belong to any particular control connection.
+ */
+static smartlist_t *detached_onion_services = NULL;
+
+/**
+ * Return a list of detached onion services, or NULL if none exist.
+ **/
+smartlist_t *
+get_detached_onion_services(void)
+{
+  return detached_onion_services;
+}
+
+/** Called when we get a ADD_ONION command; parse the body, and set up
+ * the new ephemeral Onion Service. */
+static int
+handle_control_add_onion(control_connection_t *conn,
+                         uint32_t len,
+                         const char *body)
+{
+  smartlist_t *args;
+  int arg_len;
+  (void) len; /* body is nul-terminated; it's safe to ignore the length */
+  args = getargs_helper("ADD_ONION", conn, body, 2, -1);
+  if (!args)
+    return 0;
+  arg_len = smartlist_len(args);
+
+  /* Parse all of the arguments that do not involve handling cryptographic
+   * material first, since there's no reason to touch that at all if any of
+   * the other arguments are malformed.
+   */
+  smartlist_t *port_cfgs = smartlist_new();
+  smartlist_t *auth_clients = NULL;
+  smartlist_t *auth_created_clients = NULL;
+  int discard_pk = 0;
+  int detach = 0;
+  int max_streams = 0;
+  int max_streams_close_circuit = 0;
+  rend_auth_type_t auth_type = REND_NO_AUTH;
+  /* Default to adding an anonymous hidden service if no flag is given */
+  int non_anonymous = 0;
+  for (int i = 1; i < arg_len; i++) {
+    static const char *port_prefix = "Port=";
+    static const char *flags_prefix = "Flags=";
+    static const char *max_s_prefix = "MaxStreams=";
+    static const char *auth_prefix = "ClientAuth=";
+
+    const char *arg = smartlist_get(args, (int)i);
+    if (!strcasecmpstart(arg, port_prefix)) {
+      /* "Port=VIRTPORT[,TARGET]". */
+      const char *port_str = arg + strlen(port_prefix);
+
+      rend_service_port_config_t *cfg =
+          rend_service_parse_port_config(port_str, ",", NULL);
+      if (!cfg) {
+        connection_printf_to_buf(conn, "512 Invalid VIRTPORT/TARGET\r\n");
+        goto out;
+      }
+      smartlist_add(port_cfgs, cfg);
+    } else if (!strcasecmpstart(arg, max_s_prefix)) {
+      /* "MaxStreams=[0..65535]". */
+      const char *max_s_str = arg + strlen(max_s_prefix);
+      int ok = 0;
+      max_streams = (int)tor_parse_long(max_s_str, 10, 0, 65535, &ok, NULL);
+      if (!ok) {
+        connection_printf_to_buf(conn, "512 Invalid MaxStreams\r\n");
+        goto out;
+      }
+    } else if (!strcasecmpstart(arg, flags_prefix)) {
+      /* "Flags=Flag[,Flag]", where Flag can be:
+       *   * 'DiscardPK' - If tor generates the keypair, do not include it in
+       *                   the response.
+       *   * 'Detach' - Do not tie this onion service to any particular control
+       *                connection.
+       *   * 'MaxStreamsCloseCircuit' - Close the circuit if MaxStreams is
+       *                                exceeded.
+       *   * 'BasicAuth' - Client authorization using the 'basic' method.
+       *   * 'NonAnonymous' - Add a non-anonymous Single Onion Service. If this
+       *                      flag is present, tor must be in non-anonymous
+       *                      hidden service mode. If this flag is absent,
+       *                      tor must be in anonymous hidden service mode.
+       */
+      static const char *discard_flag = "DiscardPK";
+      static const char *detach_flag = "Detach";
+      static const char *max_s_close_flag = "MaxStreamsCloseCircuit";
+      static const char *basicauth_flag = "BasicAuth";
+      static const char *non_anonymous_flag = "NonAnonymous";
+
+      smartlist_t *flags = smartlist_new();
+      int bad = 0;
+
+      smartlist_split_string(flags, arg + strlen(flags_prefix), ",",
+                             SPLIT_IGNORE_BLANK, 0);
+      if (smartlist_len(flags) < 1) {
+        connection_printf_to_buf(conn, "512 Invalid 'Flags' argument\r\n");
+        bad = 1;
+      }
+      SMARTLIST_FOREACH_BEGIN(flags, const char *, flag)
+      {
+        if (!strcasecmp(flag, discard_flag)) {
+          discard_pk = 1;
+        } else if (!strcasecmp(flag, detach_flag)) {
+          detach = 1;
+        } else if (!strcasecmp(flag, max_s_close_flag)) {
+          max_streams_close_circuit = 1;
+        } else if (!strcasecmp(flag, basicauth_flag)) {
+          auth_type = REND_BASIC_AUTH;
+        } else if (!strcasecmp(flag, non_anonymous_flag)) {
+          non_anonymous = 1;
+        } else {
+          connection_printf_to_buf(conn,
+                                   "512 Invalid 'Flags' argument: %s\r\n",
+                                   escaped(flag));
+          bad = 1;
+          break;
+        }
+      } SMARTLIST_FOREACH_END(flag);
+      SMARTLIST_FOREACH(flags, char *, cp, tor_free(cp));
+      smartlist_free(flags);
+      if (bad)
+        goto out;
+    } else if (!strcasecmpstart(arg, auth_prefix)) {
+      char *err_msg = NULL;
+      int created = 0;
+      rend_authorized_client_t *client =
+        add_onion_helper_clientauth(arg + strlen(auth_prefix),
+                                    &created, &err_msg);
+      if (!client) {
+        if (err_msg) {
+          connection_write_str_to_buf(err_msg, conn);
+          tor_free(err_msg);
+        }
+        goto out;
+      }
+
+      if (auth_clients != NULL) {
+        int bad = 0;
+        SMARTLIST_FOREACH_BEGIN(auth_clients, rend_authorized_client_t *, ac) {
+          if (strcmp(ac->client_name, client->client_name) == 0) {
+            bad = 1;
+            break;
+          }
+        } SMARTLIST_FOREACH_END(ac);
+        if (bad) {
+          connection_printf_to_buf(conn,
+                                   "512 Duplicate name in ClientAuth\r\n");
+          rend_authorized_client_free(client);
+          goto out;
+        }
+      } else {
+        auth_clients = smartlist_new();
+        auth_created_clients = smartlist_new();
+      }
+      smartlist_add(auth_clients, client);
+      if (created) {
+        smartlist_add(auth_created_clients, client);
+      }
+    } else {
+      connection_printf_to_buf(conn, "513 Invalid argument\r\n");
+      goto out;
+    }
+  }
+  if (smartlist_len(port_cfgs) == 0) {
+    connection_printf_to_buf(conn, "512 Missing 'Port' argument\r\n");
+    goto out;
+  } else if (auth_type == REND_NO_AUTH && auth_clients != NULL) {
+    connection_printf_to_buf(conn, "512 No auth type specified\r\n");
+    goto out;
+  } else if (auth_type != REND_NO_AUTH && auth_clients == NULL) {
+    connection_printf_to_buf(conn, "512 No auth clients specified\r\n");
+    goto out;
+  } else if ((auth_type == REND_BASIC_AUTH &&
+              smartlist_len(auth_clients) > 512) ||
+             (auth_type == REND_STEALTH_AUTH &&
+              smartlist_len(auth_clients) > 16)) {
+    connection_printf_to_buf(conn, "512 Too many auth clients\r\n");
+    goto out;
+  } else if (non_anonymous != rend_service_non_anonymous_mode_enabled(
+                                                              get_options())) {
+    /* If we failed, and the non-anonymous flag is set, Tor must be in
+     * anonymous hidden service mode.
+     * The error message changes based on the current Tor config:
+     * 512 Tor is in anonymous hidden service mode
+     * 512 Tor is in non-anonymous hidden service mode
+     * (I've deliberately written them out in full here to aid searchability.)
+     */
+    connection_printf_to_buf(conn, "512 Tor is in %sanonymous hidden service "
+                             "mode\r\n",
+                             non_anonymous ? "" : "non-");
+    goto out;
+  }
+
+  /* Parse the "keytype:keyblob" argument. */
+  int hs_version = 0;
+  add_onion_secret_key_t pk = { NULL };
+  const char *key_new_alg = NULL;
+  char *key_new_blob = NULL;
+  char *err_msg = NULL;
+
+  if (add_onion_helper_keyarg(smartlist_get(args, 0), discard_pk,
+                              &key_new_alg, &key_new_blob, &pk, &hs_version,
+                              &err_msg) < 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. */
+  if (hs_version == HS_VERSION_THREE && auth_clients) {
+    connection_printf_to_buf(conn, "513 ClientAuth not supported\r\n");
+    goto out;
+  }
+
+  /* Create the HS, using private key pk, client authentication auth_type,
+   * the list of auth_clients, and port config port_cfg.
+   * rend_service_add_ephemeral() will take ownership of pk and port_cfg,
+   * regardless of success/failure.
+   */
+  char *service_id = NULL;
+  int ret = add_onion_helper_add_service(hs_version, &pk, port_cfgs,
+                                         max_streams,
+                                         max_streams_close_circuit, auth_type,
+                                         auth_clients, &service_id);
+  port_cfgs = NULL; /* port_cfgs is now owned by the rendservice code. */
+  auth_clients = NULL; /* so is auth_clients */
+  switch (ret) {
+  case RSAE_OKAY:
+  {
+    if (detach) {
+      if (!detached_onion_services)
+        detached_onion_services = smartlist_new();
+      smartlist_add(detached_onion_services, service_id);
+    } else {
+      if (!conn->ephemeral_onion_services)
+        conn->ephemeral_onion_services = smartlist_new();
+      smartlist_add(conn->ephemeral_onion_services, service_id);
+    }
+
+    tor_assert(service_id);
+    connection_printf_to_buf(conn, "250-ServiceID=%s\r\n", service_id);
+    if (key_new_alg) {
+      tor_assert(key_new_blob);
+      connection_printf_to_buf(conn, "250-PrivateKey=%s:%s\r\n",
+                               key_new_alg, key_new_blob);
+    }
+    if (auth_created_clients) {
+      SMARTLIST_FOREACH(auth_created_clients, rend_authorized_client_t *, ac, {
+        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",
+                                 ac->client_name, encoded);
+        memwipe(encoded, 0, strlen(encoded));
+        tor_free(encoded);
+      });
+    }
+
+    connection_printf_to_buf(conn, "250 OK\r\n");
+    break;
+  }
+  case RSAE_BADPRIVKEY:
+    connection_printf_to_buf(conn, "551 Failed to generate onion address\r\n");
+    break;
+  case RSAE_ADDREXISTS:
+    connection_printf_to_buf(conn, "550 Onion address collision\r\n");
+    break;
+  case RSAE_BADVIRTPORT:
+    connection_printf_to_buf(conn, "512 Invalid VIRTPORT/TARGET\r\n");
+    break;
+  case RSAE_BADAUTH:
+    connection_printf_to_buf(conn, "512 Invalid client authorization\r\n");
+    break;
+  case RSAE_INTERNAL: /* FALLSTHROUGH */
+  default:
+    connection_printf_to_buf(conn, "551 Failed to add Onion Service\r\n");
+  }
+  if (key_new_blob) {
+    memwipe(key_new_blob, 0, strlen(key_new_blob));
+    tor_free(key_new_blob);
+  }
+
+ out:
+  if (port_cfgs) {
+    SMARTLIST_FOREACH(port_cfgs, rend_service_port_config_t*, p,
+                      rend_service_port_config_free(p));
+    smartlist_free(port_cfgs);
+  }
+
+  if (auth_clients) {
+    SMARTLIST_FOREACH(auth_clients, rend_authorized_client_t *, ac,
+                      rend_authorized_client_free(ac));
+    smartlist_free(auth_clients);
+  }
+  if (auth_created_clients) {
+    // Do not free entries; they are the same as auth_clients
+    smartlist_free(auth_created_clients);
+  }
+
+  SMARTLIST_FOREACH(args, char *, cp, {
+    memwipe(cp, 0, strlen(cp));
+    tor_free(cp);
+  });
+  smartlist_free(args);
+  return 0;
+}
+
+/** Helper function to handle parsing the KeyType:KeyBlob argument to the
+ * 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.
+ *
+ * Note: The error messages returned are deliberately vague to avoid echoing
+ * key material.
+ */
+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)
+{
+  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");
+    goto err;
+  }
+
+  /* The format is "KeyType:KeyBlob". */
+  static const char *key_type_new = "NEW";
+  static const char *key_type_best = "BEST";
+  static const char *key_type_rsa1024 = "RSA1024";
+  static const char *key_type_ed25519_v3 = "ED25519-V3";
+
+  const char *key_type = smartlist_get(key_args, 0);
+  const char *key_blob = smartlist_get(key_args, 1);
+
+  if (!strcasecmp(key_type_rsa1024, key_type)) {
+    /* "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");
+      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");
+      goto err;
+    }
+    decoded_key->v2 = pk;
+    *hs_version = HS_VERSION_TWO;
+  } else if (!strcasecmp(key_type_ed25519_v3, key_type)) {
+    /* "ED25519-V3:<Base64 Blob>" - Loading a pre-existing ed25519 key. */
+    ed25519_secret_key_t *sk = tor_malloc_zero(sizeof(*sk));
+    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");
+      goto err;
+    }
+    decoded_key->v3 = sk;
+    *hs_version = HS_VERSION_THREE;
+  } else if (!strcasecmp(key_type_new, key_type)) {
+    /* "NEW:<Algorithm>" - Generating a new key, blob as algorithm. */
+    if (!strcasecmp(key_type_rsa1024, key_blob) ||
+        !strcasecmp(key_type_best, key_blob)) {
+      /* "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",
+                     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",
+                       key_type_rsa1024);
+          goto err;
+        }
+        key_new_alg = key_type_rsa1024;
+      }
+      decoded_key->v2 = pk;
+      *hs_version = HS_VERSION_TWO;
+    } else if (!strcasecmp(key_type_ed25519_v3, key_blob)) {
+      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",
+                     key_type_ed25519_v3);
+        goto err;
+      }
+      if (!discard_pk) {
+        ssize_t len = base64_encode_size(sizeof(sk->seckey), 0) + 1;
+        key_new_blob = tor_malloc_zero(len);
+        if (base64_encode(key_new_blob, len, (const char *) sk->seckey,
+                          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",
+                       key_type_ed25519_v3);
+          goto err;
+        }
+        key_new_alg = key_type_ed25519_v3;
+      }
+      decoded_key->v3 = sk;
+      *hs_version = HS_VERSION_THREE;
+    } else {
+      err_msg = tor_strdup("513 Invalid key type\r\n");
+      goto err;
+    }
+  } else {
+    err_msg = tor_strdup("513 Invalid key type\r\n");
+    goto err;
+  }
+
+  /* Succeeded in loading or generating a private key. */
+  ret = 0;
+
+ err:
+  SMARTLIST_FOREACH(key_args, char *, cp, {
+    memwipe(cp, 0, strlen(cp));
+    tor_free(cp);
+  });
+  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;
+
+  return ret;
+}
+
+/** 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.
+ *
+ * If 'created' is specified, it will be set to 1 when a new cookie has
+ * been generated.
+ */
+STATIC rend_authorized_client_t *
+add_onion_helper_clientauth(const char *arg, int *created, char **err_msg)
+{
+  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");
+    goto err;
+  }
+  client->client_name = tor_strdup(smartlist_get(auth_args, 0));
+  if (smartlist_len(auth_args) == 2) {
+    char *decode_err_msg = NULL;
+    if (rend_auth_decode_cookie(smartlist_get(auth_args, 1),
+                                client->descriptor_cookie,
+                                NULL, &decode_err_msg) < 0) {
+      tor_assert(decode_err_msg);
+      tor_asprintf(err_msg, "512 %s\r\n", decode_err_msg);
+      tor_free(decode_err_msg);
+      goto err;
+    }
+    *created = 0;
+  } else {
+    crypto_rand((char *) client->descriptor_cookie, REND_DESC_COOKIE_LEN);
+    *created = 1;
+  }
+
+  if (!rend_valid_client_name(client->client_name)) {
+    *err_msg = tor_strdup("512 Invalid name in ClientAuth\r\n");
+    goto err;
+  }
+
+  ok = 1;
+ err:
+  SMARTLIST_FOREACH(auth_args, char *, item, tor_free(item));
+  smartlist_free(auth_args);
+  if (!ok) {
+    rend_authorized_client_free(client);
+    client = NULL;
+  }
+  return client;
+}
+
+/** Called when we get a DEL_ONION command; parse the body, and remove
+ * the existing ephemeral Onion Service. */
+static int
+handle_control_del_onion(control_connection_t *conn,
+                          uint32_t len,
+                          const char *body)
+{
+  int hs_version = 0;
+  smartlist_t *args;
+  (void) len; /* body is nul-terminated; it's safe to ignore the length */
+  args = getargs_helper("DEL_ONION", conn, body, 1, 1);
+  if (!args)
+    return 0;
+
+  const char *service_id = smartlist_get(args, 0);
+  if (rend_valid_v2_service_id(service_id)) {
+    hs_version = HS_VERSION_TWO;
+  } else if (hs_address_is_valid(service_id)) {
+    hs_version = HS_VERSION_THREE;
+  } else {
+    connection_printf_to_buf(conn, "512 Malformed Onion Service id\r\n");
+    goto out;
+  }
+
+  /* Determine if the onion service belongs to this particular control
+   * connection, or if it is in the global list of detached services.  If it
+   * is in neither, either the service ID is invalid in some way, or it
+   * explicitly belongs to a different control connection, and an error
+   * should be returned.
+   */
+  smartlist_t *services[2] = {
+    conn->ephemeral_onion_services,
+    detached_onion_services
+  };
+  smartlist_t *onion_services = NULL;
+  int idx = -1;
+  for (size_t i = 0; i < ARRAY_LENGTH(services); i++) {
+    idx = smartlist_string_pos(services[i], service_id);
+    if (idx != -1) {
+      onion_services = services[i];
+      break;
+    }
+  }
+  if (onion_services == NULL) {
+    connection_printf_to_buf(conn, "552 Unknown Onion Service id\r\n");
+  } else {
+    int ret = -1;
+    switch (hs_version) {
+    case HS_VERSION_TWO:
+      ret = rend_service_del_ephemeral(service_id);
+      break;
+    case HS_VERSION_THREE:
+      ret = hs_service_del_ephemeral(service_id);
+      break;
+    default:
+      /* The ret value will be -1 thus hitting the warning below. This should
+       * never happen because of the check at the start of the function. */
+      break;
+    }
+    if (ret < 0) {
+      /* This should *NEVER* fail, since the service is on either the
+       * per-control connection list, or the global one.
+       */
+      log_warn(LD_BUG, "Failed to remove Onion Service %s.",
+               escaped(service_id));
+      tor_fragile_assert();
+    }
+
+    /* Remove/scrub the service_id from the appropriate list. */
+    char *cp = smartlist_get(onion_services, idx);
+    smartlist_del(onion_services, idx);
+    memwipe(cp, 0, strlen(cp));
+    tor_free(cp);
+
+    send_control_done(conn);
+  }
+
+ out:
+  SMARTLIST_FOREACH(args, char *, cp, {
+    memwipe(cp, 0, strlen(cp));
+    tor_free(cp);
+  });
+  smartlist_free(args);
+  return 0;
+}
+
+int
+handle_control_command(control_connection_t *conn,
+                            uint32_t cmd_data_len,
+                            char *args)
+{
+  /* XXXX Why is this not implemented as a table like the GETINFO
+   * items are?  Even handling the plus signs at the beginnings of
+   * commands wouldn't be very hard with proper macros. */
+
+  if (!strcasecmp(conn->incoming_cmd, "SETCONF")) {
+    if (handle_control_setconf(conn, cmd_data_len, args))
+      return -1;
+  } else if (!strcasecmp(conn->incoming_cmd, "RESETCONF")) {
+    if (handle_control_resetconf(conn, cmd_data_len, args))
+      return -1;
+  } else if (!strcasecmp(conn->incoming_cmd, "GETCONF")) {
+    if (handle_control_getconf(conn, cmd_data_len, args))
+      return -1;
+  } else if (!strcasecmp(conn->incoming_cmd, "+LOADCONF")) {
+    if (handle_control_loadconf(conn, cmd_data_len, args))
+      return -1;
+  } else if (!strcasecmp(conn->incoming_cmd, "SETEVENTS")) {
+    if (handle_control_setevents(conn, cmd_data_len, args))
+      return -1;
+  } else if (!strcasecmp(conn->incoming_cmd, "AUTHENTICATE")) {
+    if (handle_control_authenticate(conn, cmd_data_len, args))
+      return -1;
+  } else if (!strcasecmp(conn->incoming_cmd, "SAVECONF")) {
+    if (handle_control_saveconf(conn, cmd_data_len, args))
+      return -1;
+  } else if (!strcasecmp(conn->incoming_cmd, "SIGNAL")) {
+    if (handle_control_signal(conn, cmd_data_len, args))
+      return -1;
+  } else if (!strcasecmp(conn->incoming_cmd, "TAKEOWNERSHIP")) {
+    if (handle_control_takeownership(conn, cmd_data_len, args))
+      return -1;
+  } else if (!strcasecmp(conn->incoming_cmd, "DROPOWNERSHIP")) {
+    if (handle_control_dropownership(conn, cmd_data_len, args))
+      return -1;
+  } else if (!strcasecmp(conn->incoming_cmd, "MAPADDRESS")) {
+    if (handle_control_mapaddress(conn, cmd_data_len, args))
+      return -1;
+  } else if (!strcasecmp(conn->incoming_cmd, "GETINFO")) {
+    if (handle_control_getinfo(conn, cmd_data_len, args))
+      return -1;
+  } else if (!strcasecmp(conn->incoming_cmd, "EXTENDCIRCUIT")) {
+    if (handle_control_extendcircuit(conn, cmd_data_len, args))
+      return -1;
+  } else if (!strcasecmp(conn->incoming_cmd, "SETCIRCUITPURPOSE")) {
+    if (handle_control_setcircuitpurpose(conn, cmd_data_len, args))
+      return -1;
+  } else if (!strcasecmp(conn->incoming_cmd, "SETROUTERPURPOSE")) {
+    connection_write_str_to_buf("511 SETROUTERPURPOSE is obsolete.\r\n", conn);
+  } else if (!strcasecmp(conn->incoming_cmd, "ATTACHSTREAM")) {
+    if (handle_control_attachstream(conn, cmd_data_len, args))
+      return -1;
+  } else if (!strcasecmp(conn->incoming_cmd, "+POSTDESCRIPTOR")) {
+    if (handle_control_postdescriptor(conn, cmd_data_len, args))
+      return -1;
+  } else if (!strcasecmp(conn->incoming_cmd, "REDIRECTSTREAM")) {
+    if (handle_control_redirectstream(conn, cmd_data_len, args))
+      return -1;
+  } else if (!strcasecmp(conn->incoming_cmd, "CLOSESTREAM")) {
+    if (handle_control_closestream(conn, cmd_data_len, args))
+      return -1;
+  } else if (!strcasecmp(conn->incoming_cmd, "CLOSECIRCUIT")) {
+    if (handle_control_closecircuit(conn, cmd_data_len, args))
+      return -1;
+  } else if (!strcasecmp(conn->incoming_cmd, "USEFEATURE")) {
+    if (handle_control_usefeature(conn, cmd_data_len, args))
+      return -1;
+  } else if (!strcasecmp(conn->incoming_cmd, "RESOLVE")) {
+    if (handle_control_resolve(conn, cmd_data_len, args))
+      return -1;
+  } else if (!strcasecmp(conn->incoming_cmd, "PROTOCOLINFO")) {
+    if (handle_control_protocolinfo(conn, cmd_data_len, args))
+      return -1;
+  } else if (!strcasecmp(conn->incoming_cmd, "AUTHCHALLENGE")) {
+    if (handle_control_authchallenge(conn, cmd_data_len, args))
+      return -1;
+  } else if (!strcasecmp(conn->incoming_cmd, "DROPGUARDS")) {
+    if (handle_control_dropguards(conn, cmd_data_len, args))
+      return -1;
+  } else if (!strcasecmp(conn->incoming_cmd, "HSFETCH")) {
+    if (handle_control_hsfetch(conn, cmd_data_len, args))
+      return -1;
+  } else if (!strcasecmp(conn->incoming_cmd, "+HSPOST")) {
+    if (handle_control_hspost(conn, cmd_data_len, args))
+      return -1;
+  } else if (!strcasecmp(conn->incoming_cmd, "ADD_ONION")) {
+    int ret = handle_control_add_onion(conn, cmd_data_len, args);
+    memwipe(args, 0, cmd_data_len); /* Scrub the private key. */
+    if (ret)
+      return -1;
+  } else if (!strcasecmp(conn->incoming_cmd, "DEL_ONION")) {
+    int ret = handle_control_del_onion(conn, cmd_data_len, args);
+    memwipe(args, 0, cmd_data_len); /* Scrub the service id/pk. */
+    if (ret)
+      return -1;
+  } else {
+    connection_printf_to_buf(conn, "510 Unrecognized command \"%s\"\r\n",
+                             conn->incoming_cmd);
+  }
+
+  return 0;
+}
+
+void
+control_cmd_free_all(void)
+{
+  if (detached_onion_services) { /* Free the detached onion services */
+    SMARTLIST_FOREACH(detached_onion_services, char *, cp, tor_free(cp));
+    smartlist_free(detached_onion_services);
+  }
+}