tor

control_getinfo.c (66868B)

---

/* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
* Copyright (c) 2007-2021, The Tor Project, Inc. */
/* See LICENSE for licensing information */

/**
* \file control_getinfo.c
* \brief Implementation for miscellaneous controller getinfo commands.
*/

#define CONTROL_EVENTS_PRIVATE
#define CONTROL_MODULE_PRIVATE
#define CONTROL_GETINFO_PRIVATE

#include "core/or/or.h"
#include "app/config/config.h"
#include "core/mainloop/connection.h"
#include "core/mainloop/mainloop.h"
#include "core/or/circuitlist.h"
#include "core/or/connection_edge.h"
#include "core/or/connection_or.h"
#include "core/or/policies.h"
#include "core/or/versions.h"
#include "feature/client/addressmap.h"
#include "feature/client/bridges.h"
#include "feature/client/entrynodes.h"
#include "feature/control/control.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/control/control_proto.h"
#include "feature/control/getinfo_geoip.h"
#include "feature/dircache/dirserv.h"
#include "feature/dirclient/dirclient.h"
#include "feature/dirclient/dlstatus.h"
#include "feature/dircommon/directory.h"
#include "feature/hibernate/hibernate.h"
#include "feature/hs/hs_cache.h"
#include "feature/hs_common/shared_random_client.h"
#include "feature/nodelist/authcert.h"
#include "feature/nodelist/microdesc.h"
#include "feature/nodelist/networkstatus.h"
#include "feature/nodelist/nodelist.h"
#include "feature/nodelist/routerinfo.h"
#include "feature/nodelist/routerlist.h"
#include "feature/relay/relay_find_addr.h"
#include "feature/relay/router.h"
#include "feature/relay/routermode.h"
#include "feature/relay/selftest.h"
#include "feature/stats/geoip_stats.h"
#include "feature/stats/predict_ports.h"
#include "feature/stats/rephist.h"
#include "lib/version/torversion.h"
#include "lib/encoding/kvline.h"

#include "core/or/entry_connection_st.h"
#include "core/or/or_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/control/control_cmd_args_st.h"
#include "feature/dircache/cached_dir_st.h"
#include "feature/nodelist/extrainfo_st.h"
#include "feature/nodelist/microdesc_st.h"
#include "feature/nodelist/networkstatus_st.h"
#include "feature/nodelist/node_st.h"
#include "feature/nodelist/routerinfo_st.h"
#include "feature/nodelist/routerlist_st.h"

#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

#ifndef _WIN32
#include <pwd.h>
#endif

static char *list_getinfo_options(void);
static char *download_status_to_string(const download_status_t *dl);

/** Implementation helper for GETINFO: knows the answers for various
* trivial-to-implement questions. */
static int
getinfo_helper_misc(control_connection_t *conn, const char *question,
                   char **answer, const char **errmsg)
{
 (void) conn;
 if (!strcmp(question, "version")) {
   *answer = tor_strdup(get_version());
 } else if (!strcmp(question, "bw-event-cache")) {
   *answer = get_bw_samples();
 } else if (!strcmp(question, "config-file")) {
   const char *a = get_torrc_fname(0);
   if (a)
     *answer = tor_strdup(a);
 } else if (!strcmp(question, "config-defaults-file")) {
   const char *a = get_torrc_fname(1);
   if (a)
     *answer = tor_strdup(a);
 } else if (!strcmp(question, "config-text")) {
   *answer = options_dump(get_options(), OPTIONS_DUMP_MINIMAL);
 } else if (!strcmp(question, "config-can-saveconf")) {
   *answer = tor_strdup(get_options()->IncludeUsed ? "0" : "1");
 } else if (!strcmp(question, "info/names")) {
   *answer = list_getinfo_options();
 } else if (!strcmp(question, "dormant")) {
   int dormant = rep_hist_circbuilding_dormant(time(NULL));
   *answer = tor_strdup(dormant ? "1" : "0");
 } else if (!strcmp(question, "events/names")) {
   int i;
   smartlist_t *event_names = smartlist_new();

   for (i = 0; control_event_table[i].event_name != NULL; ++i) {
     smartlist_add(event_names, (char *)control_event_table[i].event_name);
   }

   *answer = smartlist_join_strings(event_names, " ", 0, NULL);

   smartlist_free(event_names);
 } else if (!strcmp(question, "signal/names")) {
   smartlist_t *signal_names = smartlist_new();
   int j;
   for (j = 0; signal_table[j].signal_name != NULL; ++j) {
     smartlist_add(signal_names, (char*)signal_table[j].signal_name);
   }

   *answer = smartlist_join_strings(signal_names, " ", 0, NULL);

   smartlist_free(signal_names);
 } else if (!strcmp(question, "features/names")) {
   *answer = tor_strdup("VERBOSE_NAMES EXTENDED_EVENTS");
 } else if (!strcmp(question, "address") || !strcmp(question, "address/v4")) {
   tor_addr_t addr;
   if (!relay_find_addr_to_publish(get_options(), AF_INET,
                                   RELAY_FIND_ADDR_CACHE_ONLY, &addr)) {
     *errmsg = "Address unknown";
     return -1;
   }
   *answer = tor_addr_to_str_dup(&addr);
   tor_assert_nonfatal(*answer);
 } else if (!strcmp(question, "address/v6")) {
   tor_addr_t addr;
   if (!relay_find_addr_to_publish(get_options(), AF_INET6,
                                   RELAY_FIND_ADDR_CACHE_ONLY, &addr)) {
     *errmsg = "Address unknown";
     return -1;
   }
   *answer = tor_addr_to_str_dup(&addr);
   tor_assert_nonfatal(*answer);
 } else if (!strcmp(question, "traffic/read")) {
   tor_asprintf(answer, "%"PRIu64, (get_bytes_read()));
 } else if (!strcmp(question, "traffic/written")) {
   tor_asprintf(answer, "%"PRIu64, (get_bytes_written()));
 } else if (!strcmp(question, "uptime")) {
   long uptime_secs = get_uptime();
   tor_asprintf(answer, "%ld", uptime_secs);
 } else if (!strcmp(question, "process/pid")) {
   int myPid = -1;

#ifdef _WIN32
     myPid = _getpid();
#else
     myPid = getpid();
#endif

   tor_asprintf(answer, "%d", myPid);
 } else if (!strcmp(question, "process/uid")) {
#ifdef _WIN32
     *answer = tor_strdup("-1");
#else
     int myUid = geteuid();
     tor_asprintf(answer, "%d", myUid);
#endif /* defined(_WIN32) */
 } else if (!strcmp(question, "process/user")) {
#ifdef _WIN32
     *answer = tor_strdup("");
#else
     int myUid = geteuid();
     const struct passwd *myPwEntry = tor_getpwuid(myUid);

     if (myPwEntry) {
       *answer = tor_strdup(myPwEntry->pw_name);
     } else {
       *answer = tor_strdup("");
     }
#endif /* defined(_WIN32) */
 } else if (!strcmp(question, "process/descriptor-limit")) {
   int max_fds = get_max_sockets();
   tor_asprintf(answer, "%d", max_fds);
 } else if (!strcmp(question, "limits/max-mem-in-queues")) {
   tor_asprintf(answer, "%"PRIu64,
                (get_options()->MaxMemInQueues));
 } else if (!strcmp(question, "fingerprint")) {
   crypto_pk_t *server_key;
   if (!server_mode(get_options())) {
     *errmsg = "Not running in server mode";
     return -1;
   }
   server_key = get_server_identity_key();
   *answer = tor_malloc(HEX_DIGEST_LEN+1);
   crypto_pk_get_fingerprint(server_key, *answer, 0);
 }
 return 0;
}

/** Awful hack: return a newly allocated string based on a routerinfo and
* (possibly) an extrainfo, sticking the read-history and write-history from
* <b>ei</b> into the resulting string.  The thing you get back won't
* necessarily have a valid signature.
*
* New code should never use this; it's for backward compatibility.
*
* NOTE: <b>ri_body</b> is as returned by signed_descriptor_get_body: it might
* not be NUL-terminated. */
static char *
munge_extrainfo_into_routerinfo(const char *ri_body,
                               const signed_descriptor_t *ri,
                               const signed_descriptor_t *ei)
{
 char *out = NULL, *outp;
 int i;
 const char *router_sig;
 const char *ei_body = signed_descriptor_get_body(ei);
 size_t ri_len = ri->signed_descriptor_len;
 size_t ei_len = ei->signed_descriptor_len;
 if (!ei_body)
   goto bail;

 outp = out = tor_malloc(ri_len+ei_len+1);
 if (!(router_sig = tor_memstr(ri_body, ri_len, "\nrouter-signature")))
   goto bail;
 ++router_sig;
 memcpy(out, ri_body, router_sig-ri_body);
 outp += router_sig-ri_body;

 for (i=0; i < 2; ++i) {
   const char *kwd = i ? "\nwrite-history " : "\nread-history ";
   const char *cp, *eol;
   if (!(cp = tor_memstr(ei_body, ei_len, kwd)))
     continue;
   ++cp;
   if (!(eol = memchr(cp, '\n', ei_len - (cp-ei_body))))
     continue;
   memcpy(outp, cp, eol-cp+1);
   outp += eol-cp+1;
 }
 memcpy(outp, router_sig, ri_len - (router_sig-ri_body));
 *outp++ = '\0';
 tor_assert(outp-out < (int)(ri_len+ei_len+1));

 return out;
bail:
 tor_free(out);
 return tor_strndup(ri_body, ri->signed_descriptor_len);
}

/** Implementation helper for GETINFO: answers requests for information about
* which ports are bound. */
static int
getinfo_helper_listeners(control_connection_t *control_conn,
                        const char *question,
                        char **answer, const char **errmsg)
{
 int type;
 smartlist_t *res;

 (void)control_conn;
 (void)errmsg;

 if (!strcmp(question, "net/listeners/or"))
   type = CONN_TYPE_OR_LISTENER;
 else if (!strcmp(question, "net/listeners/extor"))
   type = CONN_TYPE_EXT_OR_LISTENER;
 else if (!strcmp(question, "net/listeners/dir"))
   type = CONN_TYPE_DIR_LISTENER;
 else if (!strcmp(question, "net/listeners/socks"))
   type = CONN_TYPE_AP_LISTENER;
 else if (!strcmp(question, "net/listeners/trans"))
   type = CONN_TYPE_AP_TRANS_LISTENER;
 else if (!strcmp(question, "net/listeners/natd"))
   type = CONN_TYPE_AP_NATD_LISTENER;
 else if (!strcmp(question, "net/listeners/httptunnel"))
   type = CONN_TYPE_AP_HTTP_CONNECT_LISTENER;
 else if (!strcmp(question, "net/listeners/dns"))
   type = CONN_TYPE_AP_DNS_LISTENER;
 else if (!strcmp(question, "net/listeners/control"))
   type = CONN_TYPE_CONTROL_LISTENER;
 else if (!strcmp(question, "net/listeners/metrics"))
   type = CONN_TYPE_METRICS_LISTENER;
 else
   return 0; /* unknown key */

 res = smartlist_new();
 SMARTLIST_FOREACH_BEGIN(get_connection_array(), connection_t *, conn) {
   struct sockaddr_storage ss;
   socklen_t ss_len = sizeof(ss);

   if (conn->type != type || conn->marked_for_close || !SOCKET_OK(conn->s))
     continue;

   if (getsockname(conn->s, (struct sockaddr *)&ss, &ss_len) < 0) {
     smartlist_add_asprintf(res, "%s:%d", conn->address, (int)conn->port);
   } else {
     char *tmp = tor_sockaddr_to_str((struct sockaddr *)&ss);
     smartlist_add(res, esc_for_log(tmp));
     tor_free(tmp);
   }

 } SMARTLIST_FOREACH_END(conn);

 *answer = smartlist_join_strings(res, " ", 0, NULL);

 SMARTLIST_FOREACH(res, char *, cp, tor_free(cp));
 smartlist_free(res);
 return 0;
}

/** Implementation helper for GETINFO: answers requests for information about
* the current time in both local and UTC forms. */
STATIC int
getinfo_helper_current_time(control_connection_t *control_conn,
                        const char *question,
                        char **answer, const char **errmsg)
{
 (void)control_conn;
 (void)errmsg;

 struct timeval now;
 tor_gettimeofday(&now);
 char timebuf[ISO_TIME_LEN+1];

 if (!strcmp(question, "current-time/local"))
   format_local_iso_time_nospace(timebuf, (time_t)now.tv_sec);
 else if (!strcmp(question, "current-time/utc"))
   format_iso_time_nospace(timebuf, (time_t)now.tv_sec);
 else
   return 0;

 *answer = tor_strdup(timebuf);
 return 0;
}

/** GETINFO helper for dumping different consensus flavors
* returns: 0 on success -1 on error. */
STATIC int
getinfo_helper_current_consensus(consensus_flavor_t flavor,
                                char** answer,
                                const char** errmsg)
{
 const char *flavor_name = networkstatus_get_flavor_name(flavor);
 if (BUG(!strcmp(flavor_name, "??"))) {
   *errmsg = "Internal error: unrecognized flavor name.";
   return -1;
 }
 tor_mmap_t *mapped = networkstatus_map_cached_consensus(flavor_name);
 if (mapped) {
   *answer = tor_memdup_nulterm(mapped->data, mapped->size);
   tor_munmap_file(mapped);
 }
 if (!*answer) { /* Maybe it's in the cache? */
   if (we_want_to_fetch_flavor(get_options(), flavor)) {
     const cached_dir_t *consensus = dirserv_get_consensus(flavor_name);
     if (consensus) {
       *answer = tor_strdup(consensus->dir);
     }
   }
 }
 if (!*answer) { /* generate an error */
   *errmsg = "Could not open cached consensus. "
     "Make sure FetchUselessDescriptors is set to 1.";
   return -1;
 }
 return 0;
}

/** Helper for getinfo_helper_dir.
*
* Add a signed_descriptor_t to <b>descs_out</b> for each router matching
* <b>key</b>.  The key should be either
*   - "/tor/server/authority" for our own routerinfo;
*   - "/tor/server/all" for all the routerinfos we have, concatenated;
*   - "/tor/server/fp/FP" where FP is a plus-separated sequence of
*     hex identity digests; or
*   - "/tor/server/d/D" where D is a plus-separated sequence
*     of server descriptor digests, in hex.
*
* Return 0 if we found some matching descriptors, or -1 if we do not
* have any descriptors, no matching descriptors, or if we did not
* recognize the key (URL).
* If -1 is returned *<b>msg</b> will be set to an appropriate error
* message.
*/
static int
controller_get_routerdescs(smartlist_t *descs_out, const char *key,
                       const char **msg)
{
 *msg = NULL;

 if (!strcmp(key, "/tor/server/all")) {
   routerlist_t *rl = router_get_routerlist();
   SMARTLIST_FOREACH(rl->routers, routerinfo_t *, r,
                     smartlist_add(descs_out, &(r->cache_info)));
 } else if (!strcmp(key, "/tor/server/authority")) {
   const routerinfo_t *ri = router_get_my_routerinfo();
   if (ri)
     smartlist_add(descs_out, (void*) &(ri->cache_info));
 } else if (!strcmpstart(key, "/tor/server/d/")) {
   smartlist_t *digests = smartlist_new();
   key += strlen("/tor/server/d/");
   dir_split_resource_into_fingerprints(key, digests, NULL,
                                        DSR_HEX|DSR_SORT_UNIQ);
   SMARTLIST_FOREACH(digests, const char *, d,
      {
        signed_descriptor_t *sd = router_get_by_descriptor_digest(d);
        if (sd)
          smartlist_add(descs_out,sd);
      });
   SMARTLIST_FOREACH(digests, char *, d, tor_free(d));
   smartlist_free(digests);
 } else if (!strcmpstart(key, "/tor/server/fp/")) {
   smartlist_t *digests = smartlist_new();
   time_t cutoff = time(NULL) - ROUTER_MAX_AGE_TO_PUBLISH;
   key += strlen("/tor/server/fp/");
   dir_split_resource_into_fingerprints(key, digests, NULL,
                                        DSR_HEX|DSR_SORT_UNIQ);
   SMARTLIST_FOREACH_BEGIN(digests, const char *, d) {
        if (router_digest_is_me(d)) {
          /* calling router_get_my_routerinfo() to make sure it exists */
          const routerinfo_t *ri = router_get_my_routerinfo();
          if (ri)
            smartlist_add(descs_out, (void*) &(ri->cache_info));
        } else {
          const routerinfo_t *ri = router_get_by_id_digest(d);
          /* Don't actually serve a descriptor that everyone will think is
           * expired.  This is an (ugly) workaround to keep buggy 0.1.1.10
           * Tors from downloading descriptors that they will throw away.
           */
          if (ri && ri->cache_info.published_on > cutoff)
            smartlist_add(descs_out, (void*) &(ri->cache_info));
        }
   } SMARTLIST_FOREACH_END(d);
   SMARTLIST_FOREACH(digests, char *, d, tor_free(d));
   smartlist_free(digests);
 } else {
   *msg = "Key not recognized";
   return -1;
 }

 if (!smartlist_len(descs_out)) {
   *msg = "Servers unavailable";
   return -1;
 }
 return 0;
}

/** Implementation helper for GETINFO: knows the answers for questions about
* directory information. */
STATIC int
getinfo_helper_dir(control_connection_t *control_conn,
                  const char *question, char **answer,
                  const char **errmsg)
{
 (void) control_conn;
 if (!strcmpstart(question, "desc/id/")) {
   const routerinfo_t *ri = NULL;
   const node_t *node = node_get_by_hex_id(question+strlen("desc/id/"), 0);
   if (node)
     ri = node->ri;
   if (ri) {
     const char *body = signed_descriptor_get_body(&ri->cache_info);
     if (body)
       *answer = tor_strndup(body, ri->cache_info.signed_descriptor_len);
   } else if (! we_fetch_router_descriptors(get_options())) {
     /* Descriptors won't be available, provide proper error */
     *errmsg = "We fetch microdescriptors, not router "
               "descriptors. You'll need to use md/id/* "
               "instead of desc/id/*.";
     return 0;
   }
 } else if (!strcmpstart(question, "desc/name/")) {
   const routerinfo_t *ri = NULL;
   /* XXX Setting 'warn_if_unnamed' here is a bit silly -- the
    * warning goes to the user, not to the controller. */
   const node_t *node =
     node_get_by_nickname(question+strlen("desc/name/"), 0);
   if (node)
     ri = node->ri;
   if (ri) {
     const char *body = signed_descriptor_get_body(&ri->cache_info);
     if (body)
       *answer = tor_strndup(body, ri->cache_info.signed_descriptor_len);
   } else if (! we_fetch_router_descriptors(get_options())) {
     /* Descriptors won't be available, provide proper error */
     *errmsg = "We fetch microdescriptors, not router "
               "descriptors. You'll need to use md/name/* "
               "instead of desc/name/*.";
     return 0;
   }
 } else if (!strcmp(question, "desc/download-enabled")) {
   int r = we_fetch_router_descriptors(get_options());
   tor_asprintf(answer, "%d", !!r);
 } else if (!strcmp(question, "desc/all-recent")) {
   routerlist_t *routerlist = router_get_routerlist();
   smartlist_t *sl = smartlist_new();
   if (routerlist && routerlist->routers) {
     SMARTLIST_FOREACH(routerlist->routers, const routerinfo_t *, ri,
     {
       const char *body = signed_descriptor_get_body(&ri->cache_info);
       if (body)
         smartlist_add(sl,
                 tor_strndup(body, ri->cache_info.signed_descriptor_len));
     });
   }
   *answer = smartlist_join_strings(sl, "", 0, NULL);
   SMARTLIST_FOREACH(sl, char *, c, tor_free(c));
   smartlist_free(sl);
 } else if (!strcmp(question, "desc/all-recent-extrainfo-hack")) {
   /* XXXX Remove this once Torstat asks for extrainfos. */
   routerlist_t *routerlist = router_get_routerlist();
   smartlist_t *sl = smartlist_new();
   if (routerlist && routerlist->routers) {
     SMARTLIST_FOREACH_BEGIN(routerlist->routers, const routerinfo_t *, ri) {
       const char *body = signed_descriptor_get_body(&ri->cache_info);
       signed_descriptor_t *ei = extrainfo_get_by_descriptor_digest(
                                    ri->cache_info.extra_info_digest);
       if (ei && body) {
         smartlist_add(sl, munge_extrainfo_into_routerinfo(body,
                                                       &ri->cache_info, ei));
       } else if (body) {
         smartlist_add(sl,
                 tor_strndup(body, ri->cache_info.signed_descriptor_len));
       }
     } SMARTLIST_FOREACH_END(ri);
   }
   *answer = smartlist_join_strings(sl, "", 0, NULL);
   SMARTLIST_FOREACH(sl, char *, c, tor_free(c));
   smartlist_free(sl);
 } else if (!strcmpstart(question, "hs/client/desc/id/")) {
   hostname_type_t addr_type;

   question += strlen("hs/client/desc/id/");
   if (hs_address_is_valid(question)) {
     addr_type = ONION_V3_HOSTNAME;
   } else {
     *errmsg = "Invalid address";
     return -1;
   }

   if (addr_type == ONION_V3_HOSTNAME) {
     ed25519_public_key_t service_pk;
     const char *desc;

     /* The check before this if/else makes sure of this. */
     tor_assert(addr_type == ONION_V3_HOSTNAME);

     if (hs_parse_address(question, &service_pk, NULL, NULL) < 0) {
       *errmsg = "Invalid v3 address";
       return -1;
     }

     desc = hs_cache_lookup_encoded_as_client(&service_pk);
     if (desc) {
       *answer = tor_strdup(desc);
     } else {
       *errmsg = "Not found in cache";
       return -1;
     }
   }
 } else if (!strcmpstart(question, "hs/service/desc/id/")) {
   hostname_type_t addr_type;

   question += strlen("hs/service/desc/id/");
   if (hs_address_is_valid(question)) {
     addr_type = ONION_V3_HOSTNAME;
   } else {
     *errmsg = "Invalid address";
     return -1;
   }

   if (addr_type == ONION_V3_HOSTNAME) {
     ed25519_public_key_t service_pk;
     char *desc;

     /* The check before this if/else makes sure of this. */
     tor_assert(addr_type == ONION_V3_HOSTNAME);

     if (hs_parse_address(question, &service_pk, NULL, NULL) < 0) {
       *errmsg = "Invalid v3 address";
       return -1;
     }

     desc = hs_service_lookup_current_desc(&service_pk);
     if (desc) {
       /* Newly allocated string, we have ownership. */
       *answer = desc;
     } else {
       *errmsg = "Not found in cache";
       return -1;
     }
   }
 } else if (!strcmp(question, "md/all")) {
   const smartlist_t *nodes = nodelist_get_list();
   tor_assert(nodes);

   if (smartlist_len(nodes) == 0) {
     *answer = tor_strdup("");
     return 0;
   }

   smartlist_t *microdescs = smartlist_new();

   SMARTLIST_FOREACH_BEGIN(nodes, node_t *, n) {
     if (n->md && n->md->body) {
       char *copy = tor_strndup(n->md->body, n->md->bodylen);
       smartlist_add(microdescs, copy);
     }
   } SMARTLIST_FOREACH_END(n);

   *answer = smartlist_join_strings(microdescs, "", 0, NULL);
   SMARTLIST_FOREACH(microdescs, char *, md, tor_free(md));
   smartlist_free(microdescs);
 } else if (!strcmpstart(question, "md/id/")) {
   const node_t *node = node_get_by_hex_id(question+strlen("md/id/"), 0);
   const microdesc_t *md = NULL;
   if (node) md = node->md;
   if (md && md->body) {
     *answer = tor_strndup(md->body, md->bodylen);
   }
 } else if (!strcmpstart(question, "md/name/")) {
   /* XXX Setting 'warn_if_unnamed' here is a bit silly -- the
    * warning goes to the user, not to the controller. */
   const node_t *node = node_get_by_nickname(question+strlen("md/name/"), 0);
   /* XXXX duplicated code */
   const microdesc_t *md = NULL;
   if (node) md = node->md;
   if (md && md->body) {
     *answer = tor_strndup(md->body, md->bodylen);
   }
 } else if (!strcmp(question, "md/download-enabled")) {
   int r = we_fetch_microdescriptors(get_options());
   tor_asprintf(answer, "%d", !!r);
 } else if (!strcmpstart(question, "desc-annotations/id/")) {
   const routerinfo_t *ri = NULL;
   const node_t *node =
     node_get_by_hex_id(question+strlen("desc-annotations/id/"), 0);
   if (node)
     ri = node->ri;
   if (ri) {
     const char *annotations =
       signed_descriptor_get_annotations(&ri->cache_info);
     if (annotations)
       *answer = tor_strndup(annotations,
                             ri->cache_info.annotations_len);
   }
 } else if (!strcmpstart(question, "dir/server/")) {
   size_t answer_len = 0;
   char *url = NULL;
   smartlist_t *descs = smartlist_new();
   const char *msg;
   int res;
   char *cp;
   tor_asprintf(&url, "/tor/%s", question+4);
   res = controller_get_routerdescs(descs, url, &msg);
   if (res) {
     log_warn(LD_CONTROL, "getinfo '%s': %s", question, msg);
     smartlist_free(descs);
     tor_free(url);
     *errmsg = msg;
     return -1;
   }
   SMARTLIST_FOREACH(descs, signed_descriptor_t *, sd,
                     answer_len += sd->signed_descriptor_len);
   cp = *answer = tor_malloc(answer_len+1);
   SMARTLIST_FOREACH(descs, signed_descriptor_t *, sd,
                     {
                       memcpy(cp, signed_descriptor_get_body(sd),
                              sd->signed_descriptor_len);
                       cp += sd->signed_descriptor_len;
                     });
   *cp = '\0';
   tor_free(url);
   smartlist_free(descs);
 } else if (!strcmpstart(question, "dir/status/")) {
   *answer = tor_strdup("");
 } else if (!strcmp(question, "dir/status-vote/current/consensus")) {
   int consensus_result = getinfo_helper_current_consensus(FLAV_NS,
                                                           answer, errmsg);
   if (consensus_result < 0) {
     return -1;
   }
 } else if (!strcmp(question,
                    "dir/status-vote/current/consensus-microdesc")) {
   int consensus_result = getinfo_helper_current_consensus(FLAV_MICRODESC,
                                                           answer, errmsg);
   if (consensus_result < 0) {
     return -1;
   }
 } else if (!strcmpstart(question, "extra-info/digest/")) {
   question += strlen("extra-info/digest/");
   if (strlen(question) == HEX_DIGEST_LEN) {
     char d[DIGEST_LEN];
     signed_descriptor_t *sd = NULL;
     if (base16_decode(d, sizeof(d), question, strlen(question))
                       == sizeof(d)) {
       /* XXXX this test should move into extrainfo_get_by_descriptor_digest,
        * but I don't want to risk affecting other parts of the code,
        * especially since the rules for using our own extrainfo (including
        * when it might be freed) are different from those for using one
        * we have downloaded. */
       if (router_extrainfo_digest_is_me(d))
         sd = &(router_get_my_extrainfo()->cache_info);
       else
         sd = extrainfo_get_by_descriptor_digest(d);
     }
     if (sd) {
       const char *body = signed_descriptor_get_body(sd);
       if (body)
         *answer = tor_strndup(body, sd->signed_descriptor_len);
     }
   }
 }

 return 0;
}

/** Given a smartlist of 20-byte digests, return a newly allocated string
* containing each of those digests in order, formatted in HEX, and terminated
* with a newline. */
static char *
digest_list_to_string(const smartlist_t *sl)
{
 int len;
 char *result, *s;

 /* Allow for newlines, and a \0 at the end */
 len = smartlist_len(sl) * (HEX_DIGEST_LEN + 1) + 1;
 result = tor_malloc_zero(len);

 s = result;
 SMARTLIST_FOREACH_BEGIN(sl, const char *, digest) {
   base16_encode(s, HEX_DIGEST_LEN + 1, digest, DIGEST_LEN);
   s[HEX_DIGEST_LEN] = '\n';
   s += HEX_DIGEST_LEN + 1;
 } SMARTLIST_FOREACH_END(digest);
 *s = '\0';

 return result;
}

/** Turn a download_status_t into a human-readable description in a newly
* allocated string.  The format is specified in control-spec.txt, under
* the documentation for "GETINFO download/..." .  */
static char *
download_status_to_string(const download_status_t *dl)
{
 char *rv = NULL;
 char tbuf[ISO_TIME_LEN+1];
 const char *schedule_str, *want_authority_str;
 const char *increment_on_str, *backoff_str;

 if (dl) {
   /* Get some substrings of the eventual output ready */
   format_iso_time(tbuf, download_status_get_next_attempt_at(dl));

   switch (dl->schedule) {
     case DL_SCHED_GENERIC:
       schedule_str = "DL_SCHED_GENERIC";
       break;
     case DL_SCHED_CONSENSUS:
       schedule_str = "DL_SCHED_CONSENSUS";
       break;
     case DL_SCHED_BRIDGE:
       schedule_str = "DL_SCHED_BRIDGE";
       break;
     default:
       schedule_str = "unknown";
       break;
   }

   switch (dl->want_authority) {
     case DL_WANT_ANY_DIRSERVER:
       want_authority_str = "DL_WANT_ANY_DIRSERVER";
       break;
     case DL_WANT_AUTHORITY:
       want_authority_str = "DL_WANT_AUTHORITY";
       break;
     default:
       want_authority_str = "unknown";
       break;
   }

   switch (dl->increment_on) {
     case DL_SCHED_INCREMENT_FAILURE:
       increment_on_str = "DL_SCHED_INCREMENT_FAILURE";
       break;
     case DL_SCHED_INCREMENT_ATTEMPT:
       increment_on_str = "DL_SCHED_INCREMENT_ATTEMPT";
       break;
     default:
       increment_on_str = "unknown";
       break;
   }

   backoff_str = "DL_SCHED_RANDOM_EXPONENTIAL";

   /* Now assemble them */
   tor_asprintf(&rv,
                "next-attempt-at %s\n"
                "n-download-failures %u\n"
                "n-download-attempts %u\n"
                "schedule %s\n"
                "want-authority %s\n"
                "increment-on %s\n"
                "backoff %s\n"
                "last-backoff-position %u\n"
                "last-delay-used %d\n",
                tbuf,
                dl->n_download_failures,
                dl->n_download_attempts,
                schedule_str,
                want_authority_str,
                increment_on_str,
                backoff_str,
                dl->last_backoff_position,
                dl->last_delay_used);
 }

 return rv;
}

/** Handle the consensus download cases for getinfo_helper_downloads() */
STATIC void
getinfo_helper_downloads_networkstatus(const char *flavor,
                                      download_status_t **dl_to_emit,
                                      const char **errmsg)
{
 /*
  * We get the one for the current bootstrapped status by default, or
  * take an extra /bootstrap or /running suffix
  */
 if (strcmp(flavor, "ns") == 0) {
   *dl_to_emit = networkstatus_get_dl_status_by_flavor(FLAV_NS);
 } else if (strcmp(flavor, "ns/bootstrap") == 0) {
   *dl_to_emit = networkstatus_get_dl_status_by_flavor_bootstrap(FLAV_NS);
 } else if (strcmp(flavor, "ns/running") == 0 ) {
   *dl_to_emit = networkstatus_get_dl_status_by_flavor_running(FLAV_NS);
 } else if (strcmp(flavor, "microdesc") == 0) {
   *dl_to_emit = networkstatus_get_dl_status_by_flavor(FLAV_MICRODESC);
 } else if (strcmp(flavor, "microdesc/bootstrap") == 0) {
   *dl_to_emit =
     networkstatus_get_dl_status_by_flavor_bootstrap(FLAV_MICRODESC);
 } else if (strcmp(flavor, "microdesc/running") == 0) {
   *dl_to_emit =
     networkstatus_get_dl_status_by_flavor_running(FLAV_MICRODESC);
 } else {
   *errmsg = "Unknown flavor";
 }
}

/** Handle the cert download cases for getinfo_helper_downloads() */
STATIC void
getinfo_helper_downloads_cert(const char *fp_sk_req,
                             download_status_t **dl_to_emit,
                             smartlist_t **digest_list,
                             const char **errmsg)
{
 const char *sk_req;
 char id_digest[DIGEST_LEN];
 char sk_digest[DIGEST_LEN];

 /*
  * We have to handle four cases; fp_sk_req is the request with
  * a prefix of "downloads/cert/" snipped off.
  *
  * Case 1: fp_sk_req = "fps"
  *  - We should emit a digest_list with a list of all the identity
  *    fingerprints that can be queried for certificate download status;
  *    get it by calling list_authority_ids_with_downloads().
  *
  * Case 2: fp_sk_req = "fp/<fp>" for some fingerprint fp
  *  - We want the default certificate for this identity fingerprint's
  *    download status; this is the download we get from URLs starting
  *    in /fp/ on the directory server.  We can get it with
  *    id_only_download_status_for_authority_id().
  *
  * Case 3: fp_sk_req = "fp/<fp>/sks" for some fingerprint fp
  *  - We want a list of all signing key digests for this identity
  *    fingerprint which can be queried for certificate download status.
  *    Get it with list_sk_digests_for_authority_id().
  *
  * Case 4: fp_sk_req = "fp/<fp>/<sk>" for some fingerprint fp and
  *         signing key digest sk
  *   - We want the download status for the certificate for this specific
  *     signing key and fingerprint.  These correspond to the ones we get
  *     from URLs starting in /fp-sk/ on the directory server.  Get it with
  *     list_sk_digests_for_authority_id().
  */

 if (strcmp(fp_sk_req, "fps") == 0) {
   *digest_list = list_authority_ids_with_downloads();
   if (!(*digest_list)) {
     *errmsg = "Failed to get list of authority identity digests (!)";
   }
 } else if (!strcmpstart(fp_sk_req, "fp/")) {
   fp_sk_req += strlen("fp/");
   /* Okay, look for another / to tell the fp from fp-sk cases */
   sk_req = strchr(fp_sk_req, '/');
   if (sk_req) {
     /* okay, split it here and try to parse <fp> */
     if (base16_decode(id_digest, DIGEST_LEN,
                       fp_sk_req, sk_req - fp_sk_req) == DIGEST_LEN) {
       /* Skip past the '/' */
       ++sk_req;
       if (strcmp(sk_req, "sks") == 0) {
         /* We're asking for the list of signing key fingerprints */
         *digest_list = list_sk_digests_for_authority_id(id_digest);
         if (!(*digest_list)) {
           *errmsg = "Failed to get list of signing key digests for this "
                     "authority identity digest";
         }
       } else {
         /* We've got a signing key digest */
         if (base16_decode(sk_digest, DIGEST_LEN,
                           sk_req, strlen(sk_req)) == DIGEST_LEN) {
           *dl_to_emit =
             download_status_for_authority_id_and_sk(id_digest, sk_digest);
           if (!(*dl_to_emit)) {
             *errmsg = "Failed to get download status for this identity/"
                       "signing key digest pair";
           }
         } else {
           *errmsg = "That didn't look like a signing key digest";
         }
       }
     } else {
       *errmsg = "That didn't look like an identity digest";
     }
   } else {
     /* We're either in downloads/certs/fp/<fp>, or we can't parse <fp> */
     if (strlen(fp_sk_req) == HEX_DIGEST_LEN) {
       if (base16_decode(id_digest, DIGEST_LEN,
                         fp_sk_req, strlen(fp_sk_req)) == DIGEST_LEN) {
         *dl_to_emit = id_only_download_status_for_authority_id(id_digest);
         if (!(*dl_to_emit)) {
           *errmsg = "Failed to get download status for this authority "
                     "identity digest";
         }
       } else {
         *errmsg = "That didn't look like a digest";
       }
     } else {
       *errmsg = "That didn't look like a digest";
     }
   }
 } else {
   *errmsg = "Unknown certificate download status query";
 }
}

/** Handle the routerdesc download cases for getinfo_helper_downloads() */
STATIC void
getinfo_helper_downloads_desc(const char *desc_req,
                             download_status_t **dl_to_emit,
                             smartlist_t **digest_list,
                             const char **errmsg)
{
 char desc_digest[DIGEST_LEN];
 /*
  * Two cases to handle here:
  *
  * Case 1: desc_req = "descs"
  *   - Emit a list of all router descriptor digests, which we get by
  *     calling router_get_descriptor_digests(); this can return NULL
  *     if we have no current ns-flavor consensus.
  *
  * Case 2: desc_req = <fp>
  *   - Check on the specified fingerprint and emit its download_status_t
  *     using router_get_dl_status_by_descriptor_digest().
  */

 if (strcmp(desc_req, "descs") == 0) {
   *digest_list = router_get_descriptor_digests();
   if (!(*digest_list)) {
     *errmsg = "We don't seem to have a networkstatus-flavored consensus";
   }
   /*
    * Microdescs don't use the download_status_t mechanism, so we don't
    * answer queries about their downloads here; see microdesc.c.
    */
 } else if (strlen(desc_req) == HEX_DIGEST_LEN) {
   if (base16_decode(desc_digest, DIGEST_LEN,
                     desc_req, strlen(desc_req)) == DIGEST_LEN) {
     /* Okay we got a digest-shaped thing; try asking for it */
     *dl_to_emit = router_get_dl_status_by_descriptor_digest(desc_digest);
     if (!(*dl_to_emit)) {
       *errmsg = "No such descriptor digest found";
     }
   } else {
     *errmsg = "That didn't look like a digest";
   }
 } else {
   *errmsg = "Unknown router descriptor download status query";
 }
}

/** Handle the bridge download cases for getinfo_helper_downloads() */
STATIC void
getinfo_helper_downloads_bridge(const char *bridge_req,
                               download_status_t **dl_to_emit,
                               smartlist_t **digest_list,
                               const char **errmsg)
{
 char bridge_digest[DIGEST_LEN];
 /*
  * Two cases to handle here:
  *
  * Case 1: bridge_req = "bridges"
  *   - Emit a list of all bridge identity digests, which we get by
  *     calling list_bridge_identities(); this can return NULL if we are
  *     not using bridges.
  *
  * Case 2: bridge_req = <fp>
  *   - Check on the specified fingerprint and emit its download_status_t
  *     using get_bridge_dl_status_by_id().
  */

 if (strcmp(bridge_req, "bridges") == 0) {
   *digest_list = list_bridge_identities();
   if (!(*digest_list)) {
     *errmsg = "We don't seem to be using bridges";
   }
 } else if (strlen(bridge_req) == HEX_DIGEST_LEN) {
   if (base16_decode(bridge_digest, DIGEST_LEN,
                     bridge_req, strlen(bridge_req)) == DIGEST_LEN) {
     /* Okay we got a digest-shaped thing; try asking for it */
     *dl_to_emit = get_bridge_dl_status_by_id(bridge_digest);
     if (!(*dl_to_emit)) {
       *errmsg = "No such bridge identity digest found";
     }
   } else {
     *errmsg = "That didn't look like a digest";
   }
 } else {
   *errmsg = "Unknown bridge descriptor download status query";
 }
}

/** Implementation helper for GETINFO: knows the answers for questions about
* download status information. */
STATIC int
getinfo_helper_downloads(control_connection_t *control_conn,
                  const char *question, char **answer,
                  const char **errmsg)
{
 download_status_t *dl_to_emit = NULL;
 smartlist_t *digest_list = NULL;

 /* Assert args are sane */
 tor_assert(control_conn != NULL);
 tor_assert(question != NULL);
 tor_assert(answer != NULL);
 tor_assert(errmsg != NULL);

 /* We check for this later to see if we should supply a default */
 *errmsg = NULL;

 /* Are we after networkstatus downloads? */
 if (!strcmpstart(question, "downloads/networkstatus/")) {
   getinfo_helper_downloads_networkstatus(
       question + strlen("downloads/networkstatus/"),
       &dl_to_emit, errmsg);
 /* Certificates? */
 } else if (!strcmpstart(question, "downloads/cert/")) {
   getinfo_helper_downloads_cert(
       question + strlen("downloads/cert/"),
       &dl_to_emit, &digest_list, errmsg);
 /* Router descriptors? */
 } else if (!strcmpstart(question, "downloads/desc/")) {
   getinfo_helper_downloads_desc(
       question + strlen("downloads/desc/"),
       &dl_to_emit, &digest_list, errmsg);
 /* Bridge descriptors? */
 } else if (!strcmpstart(question, "downloads/bridge/")) {
   getinfo_helper_downloads_bridge(
       question + strlen("downloads/bridge/"),
       &dl_to_emit, &digest_list, errmsg);
 } else {
   *errmsg = "Unknown download status query";
 }

 if (dl_to_emit) {
   *answer = download_status_to_string(dl_to_emit);

   return 0;
 } else if (digest_list) {
   *answer = digest_list_to_string(digest_list);
   SMARTLIST_FOREACH(digest_list, void *, s, tor_free(s));
   smartlist_free(digest_list);

   return 0;
 } else {
   if (!(*errmsg)) {
     *errmsg = "Unknown error";
   }

   return -1;
 }
}

/** Implementation helper for GETINFO: knows how to generate summaries of the
* current states of things we send events about. */
static int
getinfo_helper_events(control_connection_t *control_conn,
                     const char *question, char **answer,
                     const char **errmsg)
{
 const or_options_t *options = get_options();
 (void) control_conn;
 if (!strcmp(question, "circuit-status")) {
   smartlist_t *status = smartlist_new();
   SMARTLIST_FOREACH_BEGIN(circuit_get_global_list(), circuit_t *, circ_) {
     origin_circuit_t *circ;
     char *circdesc;
     const char *state;
     if (! CIRCUIT_IS_ORIGIN(circ_) || circ_->marked_for_close)
       continue;
     circ = TO_ORIGIN_CIRCUIT(circ_);

     if (circ->base_.state == CIRCUIT_STATE_OPEN)
       state = "BUILT";
     else if (circ->base_.state == CIRCUIT_STATE_GUARD_WAIT)
       state = "GUARD_WAIT";
     else if (circ->cpath)
       state = "EXTENDED";
     else
       state = "LAUNCHED";

     circdesc = circuit_describe_status_for_controller(circ);

     smartlist_add_asprintf(status, "%lu %s%s%s",
                  (unsigned long)circ->global_identifier,
                  state, *circdesc ? " " : "", circdesc);
     tor_free(circdesc);
   }
   SMARTLIST_FOREACH_END(circ_);
   *answer = smartlist_join_strings(status, "\r\n", 0, NULL);
   SMARTLIST_FOREACH(status, char *, cp, tor_free(cp));
   smartlist_free(status);
 } else if (!strcmp(question, "stream-status")) {
   smartlist_t *conns = get_connection_array();
   smartlist_t *status = smartlist_new();
   char buf[256];
   SMARTLIST_FOREACH_BEGIN(conns, connection_t *, base_conn) {
     const char *state;
     entry_connection_t *conn;
     circuit_t *circ;
     origin_circuit_t *origin_circ = NULL;
     if (base_conn->type != CONN_TYPE_AP ||
         base_conn->marked_for_close ||
         base_conn->state == AP_CONN_STATE_SOCKS_WAIT ||
         base_conn->state == AP_CONN_STATE_NATD_WAIT)
       continue;
     conn = TO_ENTRY_CONN(base_conn);
     switch (base_conn->state)
       {
       case AP_CONN_STATE_CONTROLLER_WAIT:
       case AP_CONN_STATE_CIRCUIT_WAIT:
         if (conn->socks_request &&
             SOCKS_COMMAND_IS_RESOLVE(conn->socks_request->command))
           state = "NEWRESOLVE";
         else
           state = "NEW";
         break;
       case AP_CONN_STATE_RENDDESC_WAIT:
       case AP_CONN_STATE_CONNECT_WAIT:
         state = "SENTCONNECT"; break;
       case AP_CONN_STATE_RESOLVE_WAIT:
         state = "SENTRESOLVE"; break;
       case AP_CONN_STATE_OPEN:
         state = "SUCCEEDED"; break;
       default:
         log_warn(LD_BUG, "Asked for stream in unknown state %d",
                  base_conn->state);
         continue;
       }
     circ = circuit_get_by_edge_conn(ENTRY_TO_EDGE_CONN(conn));
     if (circ && CIRCUIT_IS_ORIGIN(circ))
       origin_circ = TO_ORIGIN_CIRCUIT(circ);
     write_stream_target_to_buf(conn, buf, sizeof(buf));
     smartlist_add_asprintf(status, "%lu %s %lu %s",
                  (unsigned long) base_conn->global_identifier,state,
                  origin_circ?
                        (unsigned long)origin_circ->global_identifier : 0ul,
                  buf);
   } SMARTLIST_FOREACH_END(base_conn);
   *answer = smartlist_join_strings(status, "\r\n", 0, NULL);
   SMARTLIST_FOREACH(status, char *, cp, tor_free(cp));
   smartlist_free(status);
 } else if (!strcmp(question, "orconn-status")) {
   smartlist_t *conns = get_connection_array();
   smartlist_t *status = smartlist_new();
   SMARTLIST_FOREACH_BEGIN(conns, connection_t *, base_conn) {
     const char *state;
     char name[128];
     or_connection_t *conn;
     if (base_conn->type != CONN_TYPE_OR || base_conn->marked_for_close)
       continue;
     conn = TO_OR_CONN(base_conn);
     if (conn->base_.state == OR_CONN_STATE_OPEN)
       state = "CONNECTED";
     else if (conn->nickname)
       state = "LAUNCHED";
     else
       state = "NEW";
     orconn_target_get_name(name, sizeof(name), conn);
     smartlist_add_asprintf(status, "%s %s", name, state);
   } SMARTLIST_FOREACH_END(base_conn);
   *answer = smartlist_join_strings(status, "\r\n", 0, NULL);
   SMARTLIST_FOREACH(status, char *, cp, tor_free(cp));
   smartlist_free(status);
 } else if (!strcmpstart(question, "address-mappings/")) {
   time_t min_e, max_e;
   smartlist_t *mappings;
   question += strlen("address-mappings/");
   if (!strcmp(question, "all")) {
     min_e = 0; max_e = TIME_MAX;
   } else if (!strcmp(question, "cache")) {
     min_e = 2; max_e = TIME_MAX;
   } else if (!strcmp(question, "config")) {
     min_e = 0; max_e = 0;
   } else if (!strcmp(question, "control")) {
     min_e = 1; max_e = 1;
   } else {
     return 0;
   }
   mappings = smartlist_new();
   addressmap_get_mappings(mappings, min_e, max_e, 1);
   *answer = smartlist_join_strings(mappings, "\r\n", 0, NULL);
   SMARTLIST_FOREACH(mappings, char *, cp, tor_free(cp));
   smartlist_free(mappings);
 } else if (!strcmpstart(question, "status/")) {
   /* Note that status/ is not a catch-all for events; there's only supposed
    * to be a status GETINFO if there's a corresponding STATUS event. */
   if (!strcmp(question, "status/circuit-established")) {
     *answer = tor_strdup(have_completed_a_circuit() ? "1" : "0");
   } else if (!strcmp(question, "status/enough-dir-info")) {
     *answer = tor_strdup(router_have_minimum_dir_info() ? "1" : "0");
   } else if (!strcmp(question, "status/good-server-descriptor") ||
              !strcmp(question, "status/accepted-server-descriptor")) {
     /* They're equivalent for now, until we can figure out how to make
      * good-server-descriptor be what we want. See comment in
      * control-spec.txt. */
     *answer = tor_strdup(directories_have_accepted_server_descriptor()
                          ? "1" : "0");
   } else if (!strcmp(question, "status/reachability-succeeded/or")) {
     *answer = tor_strdup(
                   router_all_orports_seem_reachable(options) ?
                   "1" : "0");
   } else if (!strcmp(question, "status/reachability-succeeded/dir")) {
     *answer = tor_strdup("1"); /* obsolete since tor#2667) */
   } else if (!strcmp(question, "status/reachability-succeeded")) {
     tor_asprintf(
         answer, "OR=%d DIR=%d",
         router_all_orports_seem_reachable(options) ? 1 : 0,
         1);
   } else if (!strcmp(question, "status/bootstrap-phase")) {
     *answer = control_event_boot_last_msg();
   } else if (!strcmpstart(question, "status/version/")) {
     int is_server = server_mode(options);
     networkstatus_t *c = networkstatus_get_latest_consensus();
     version_status_t status;
     const char *recommended;
     if (c) {
       recommended = is_server ? c->server_versions : c->client_versions;
       status = tor_version_is_obsolete(VERSION, recommended);
     } else {
       recommended = "?";
       status = VS_UNKNOWN;
     }

     if (!strcmp(question, "status/version/recommended")) {
       *answer = tor_strdup(recommended);
       return 0;
     }
     if (!strcmp(question, "status/version/current")) {
       switch (status)
         {
         case VS_RECOMMENDED: *answer = tor_strdup("recommended"); break;
         case VS_OLD: *answer = tor_strdup("obsolete"); break;
         case VS_NEW: *answer = tor_strdup("new"); break;
         case VS_NEW_IN_SERIES: *answer = tor_strdup("new in series"); break;
         case VS_UNRECOMMENDED: *answer = tor_strdup("unrecommended"); break;
         case VS_EMPTY: *answer = tor_strdup("none recommended"); break;
         case VS_UNKNOWN: *answer = tor_strdup("unknown"); break;
         default: tor_fragile_assert();
         }
     }
   } else if (!strcmp(question, "status/clients-seen")) {
     char *bridge_stats = geoip_get_bridge_stats_controller(time(NULL));
     if (!bridge_stats) {
       *errmsg = "No bridge-client stats available";
       return -1;
     }
     *answer = bridge_stats;
   } else if (!strcmp(question, "status/fresh-relay-descs")) {
     if (!server_mode(options)) {
       *errmsg = "Only relays have descriptors";
       return -1;
     }
     routerinfo_t *r;
     extrainfo_t *e;
     int result;
     if ((result = router_build_fresh_descriptor(&r, &e)) < 0) {
       switch (result) {
         case TOR_ROUTERINFO_ERROR_NO_EXT_ADDR:
           *errmsg = "Cannot get relay address while generating descriptor";
           break;
         case TOR_ROUTERINFO_ERROR_DIGEST_FAILED:
           *errmsg = "Key digest failed";
           break;
         case TOR_ROUTERINFO_ERROR_CANNOT_GENERATE:
           *errmsg = "Cannot generate router descriptor";
           break;
         default:
           *errmsg = "Error generating descriptor";
           break;
       }
       return -1;
     }
     size_t size = r->cache_info.signed_descriptor_len + 1;
     if (e) {
       size += e->cache_info.signed_descriptor_len + 1;
     }
     tor_assert(r->cache_info.signed_descriptor_len);
     char *descs = tor_malloc(size);
     char *cp = descs;
     memcpy(cp, signed_descriptor_get_body(&r->cache_info),
            r->cache_info.signed_descriptor_len);
     cp += r->cache_info.signed_descriptor_len - 1;
     if (e) {
       if (cp[0] == '\0') {
         cp[0] = '\n';
       } else if (cp[0] != '\n') {
         cp[1] = '\n';
         cp++;
       }
       memcpy(cp, signed_descriptor_get_body(&e->cache_info),
              e->cache_info.signed_descriptor_len);
       cp += e->cache_info.signed_descriptor_len - 1;
     }
     if (cp[0] == '\n') {
       cp[0] = '\0';
     } else if (cp[0] != '\0') {
       cp[1] = '\0';
     }
     *answer = descs;
     routerinfo_free(r);
     extrainfo_free(e);
   } else {
     return 0;
   }
 }
 return 0;
}

/** Implementation helper for GETINFO: knows how to enumerate hidden services
* created via the control port. */
STATIC int
getinfo_helper_onions(control_connection_t *control_conn,
                     const char *question, char **answer,
                     const char **errmsg)
{
 smartlist_t *onion_list = NULL;
 (void) errmsg;  /* no errors from this method */

 if (control_conn && !strcmp(question, "onions/current")) {
   onion_list = control_conn->ephemeral_onion_services;
 } else if (!strcmp(question, "onions/detached")) {
   onion_list = get_detached_onion_services();
 } else {
   return 0;
 }
 if (!onion_list || smartlist_len(onion_list) == 0) {
   if (answer) {
     *answer = tor_strdup("");
   }
 } else {
   if (answer) {
     *answer = smartlist_join_strings(onion_list, "\r\n", 0, NULL);
   }
 }

 return 0;
}

/** Implementation helper for GETINFO: answers queries about network
* liveness. */
static int
getinfo_helper_liveness(control_connection_t *control_conn,
                     const char *question, char **answer,
                     const char **errmsg)
{
 (void)control_conn;
 (void)errmsg;
 if (strcmp(question, "network-liveness") == 0) {
   if (get_cached_network_liveness()) {
     *answer = tor_strdup("up");
   } else {
     *answer = tor_strdup("down");
   }
 }

 return 0;
}

/** Implementation helper for GETINFO: answers queries about circuit onion
* handshake rephist values */
STATIC int
getinfo_helper_rephist(control_connection_t *control_conn,
                      const char *question, char **answer,
                      const char **errmsg)
{
 (void) control_conn;
 (void) errmsg;
 int result;

 if (!strcmp(question, "stats/ntor/assigned")) {
   result =
     rep_hist_get_circuit_handshake_assigned(ONION_HANDSHAKE_TYPE_NTOR);
 } else if (!strcmp(question, "stats/ntor/requested")) {
   result =
     rep_hist_get_circuit_handshake_requested(ONION_HANDSHAKE_TYPE_NTOR);
 } else if (!strcmp(question, "stats/tap/assigned")) {
   result =
     rep_hist_get_circuit_handshake_assigned(ONION_HANDSHAKE_TYPE_TAP);
 } else if (!strcmp(question, "stats/tap/requested")) {
   result =
     rep_hist_get_circuit_handshake_requested(ONION_HANDSHAKE_TYPE_TAP);
 } else {
   *errmsg = "Unrecognized handshake type";
   return -1;
 }

 tor_asprintf(answer, "%d", result);

 return 0;
}

/** Implementation helper for GETINFO: answers queries about shared random
* value. */
static int
getinfo_helper_sr(control_connection_t *control_conn,
                 const char *question, char **answer,
                 const char **errmsg)
{
 (void) control_conn;
 (void) errmsg;

 if (!strcmp(question, "sr/current")) {
   *answer = sr_get_current_for_control();
 } else if (!strcmp(question, "sr/previous")) {
   *answer = sr_get_previous_for_control();
 }
 /* Else statement here is unrecognized key so do nothing. */

 return 0;
}

/** Callback function for GETINFO: on a given control connection, try to
* answer the question <b>q</b> and store the newly-allocated answer in
* *<b>a</b>. If an internal error occurs, return -1 and optionally set
* *<b>error_out</b> to point to an error message to be delivered to the
* controller. On success, _or if the key is not recognized_, return 0. Do not
* set <b>a</b> if the key is not recognized but you may set <b>error_out</b>
* to improve the error message.
*/
typedef int (*getinfo_helper_t)(control_connection_t *,
                               const char *q, char **a,
                               const char **error_out);

/** A single item for the GETINFO question-to-answer-function table. */
typedef struct getinfo_item_t {
 const char *varname; /**< The value (or prefix) of the question. */
 getinfo_helper_t fn; /**< The function that knows the answer: NULL if
                       * this entry is documentation-only. */
 const char *desc; /**< Description of the variable. */
 int is_prefix; /** Must varname match exactly, or must it be a prefix? */
} getinfo_item_t;

#define ITEM(name, fn, desc) { name, getinfo_helper_##fn, desc, 0 }
#define PREFIX(name, fn, desc) { name, getinfo_helper_##fn, desc, 1 }
#define DOC(name, desc) { name, NULL, desc, 0 }

/** Table mapping questions accepted by GETINFO to the functions that know how
* to answer them. */
static const getinfo_item_t getinfo_items[] = {
 ITEM("version", misc, "The current version of Tor."),
 ITEM("bw-event-cache", misc, "Cached BW events for a short interval."),
 ITEM("config-file", misc, "Current location of the \"torrc\" file."),
 ITEM("config-defaults-file", misc, "Current location of the defaults file."),
 ITEM("config-text", misc,
      "Return the string that would be written by a saveconf command."),
 ITEM("config-can-saveconf", misc,
      "Is it possible to save the configuration to the \"torrc\" file?"),
 ITEM("accounting/bytes", accounting,
      "Number of bytes read/written so far in the accounting interval."),
 ITEM("accounting/bytes-left", accounting,
     "Number of bytes left to write/read so far in the accounting interval."),
 ITEM("accounting/enabled", accounting, "Is accounting currently enabled?"),
 ITEM("accounting/hibernating", accounting, "Are we hibernating or awake?"),
 ITEM("accounting/interval-start", accounting,
      "Time when the accounting period starts."),
 ITEM("accounting/interval-end", accounting,
      "Time when the accounting period ends."),
 ITEM("accounting/interval-wake", accounting,
      "Time to wake up in this accounting period."),
 ITEM("helper-nodes", entry_guards, NULL), /* deprecated */
 ITEM("entry-guards", entry_guards,
      "Which nodes are we using as entry guards?"),
 ITEM("fingerprint", misc, NULL),
 PREFIX("config/", config, "Current configuration values."),
 DOC("config/names",
     "List of configuration options, types, and documentation."),
 DOC("config/defaults",
     "List of default values for configuration options. "
     "See also config/names"),
 PREFIX("current-time/", current_time, "Current time."),
 DOC("current-time/local", "Current time on the local system."),
 DOC("current-time/utc", "Current UTC time."),
 PREFIX("downloads/networkstatus/", downloads,
        "Download statuses for networkstatus objects"),
 DOC("downloads/networkstatus/ns",
     "Download status for current-mode networkstatus download"),
 DOC("downloads/networkstatus/ns/bootstrap",
     "Download status for bootstrap-time networkstatus download"),
 DOC("downloads/networkstatus/ns/running",
     "Download status for run-time networkstatus download"),
 DOC("downloads/networkstatus/microdesc",
     "Download status for current-mode microdesc download"),
 DOC("downloads/networkstatus/microdesc/bootstrap",
     "Download status for bootstrap-time microdesc download"),
 DOC("downloads/networkstatus/microdesc/running",
     "Download status for run-time microdesc download"),
 PREFIX("downloads/cert/", downloads,
        "Download statuses for certificates, by id fingerprint and "
        "signing key"),
 DOC("downloads/cert/fps",
     "List of authority fingerprints for which any download statuses "
     "exist"),
 DOC("downloads/cert/fp/<fp>",
     "Download status for <fp> with the default signing key; corresponds "
     "to /fp/ URLs on directory server."),
 DOC("downloads/cert/fp/<fp>/sks",
     "List of signing keys for which specific download statuses are "
     "available for this id fingerprint"),
 DOC("downloads/cert/fp/<fp>/<sk>",
     "Download status for <fp> with signing key <sk>; corresponds "
     "to /fp-sk/ URLs on directory server."),
 PREFIX("downloads/desc/", downloads,
        "Download statuses for router descriptors, by descriptor digest"),
 DOC("downloads/desc/descs",
     "Return a list of known router descriptor digests"),
 DOC("downloads/desc/<desc>",
     "Return a download status for a given descriptor digest"),
 PREFIX("downloads/bridge/", downloads,
        "Download statuses for bridge descriptors, by bridge identity "
        "digest"),
 DOC("downloads/bridge/bridges",
     "Return a list of configured bridge identity digests with download "
     "statuses"),
 DOC("downloads/bridge/<desc>",
     "Return a download status for a given bridge identity digest"),
 ITEM("info/names", misc,
      "List of GETINFO options, types, and documentation."),
 ITEM("events/names", misc,
      "Events that the controller can ask for with SETEVENTS."),
 ITEM("signal/names", misc, "Signal names recognized by the SIGNAL command"),
 ITEM("features/names", misc, "What arguments can USEFEATURE take?"),
 PREFIX("desc/id/", dir, "Router descriptors by ID."),
 PREFIX("desc/name/", dir, "Router descriptors by nickname."),
 ITEM("desc/all-recent", dir,
      "All non-expired, non-superseded router descriptors."),
 ITEM("desc/download-enabled", dir,
      "Do we try to download router descriptors?"),
 ITEM("desc/all-recent-extrainfo-hack", dir, NULL), /* Hack. */
 ITEM("md/all", dir, "All known microdescriptors."),
 PREFIX("md/id/", dir, "Microdescriptors by ID"),
 PREFIX("md/name/", dir, "Microdescriptors by name"),
 ITEM("md/download-enabled", dir,
      "Do we try to download microdescriptors?"),
 PREFIX("extra-info/digest/", dir, "Extra-info documents by digest."),
 PREFIX("hs/client/desc/id", dir,
        "Hidden Service descriptor in client's cache by onion."),
 PREFIX("hs/service/desc/id/", dir,
        "Hidden Service descriptor in services's cache by onion."),
 PREFIX("net/listeners/", listeners, "Bound addresses by type"),
 ITEM("ns/all", networkstatus,
      "Brief summary of router status (v2 directory format)"),
 PREFIX("ns/id/", networkstatus,
        "Brief summary of router status by ID (v2 directory format)."),
 PREFIX("ns/name/", networkstatus,
        "Brief summary of router status by nickname (v2 directory format)."),
 PREFIX("ns/purpose/", networkstatus,
        "Brief summary of router status by purpose (v2 directory format)."),
 PREFIX("consensus/", networkstatus,
        "Information about and from the ns consensus."),
 ITEM("network-status", dir,
      "Brief summary of router status (v1 directory format)"),
 ITEM("network-liveness", liveness,
      "Current opinion on whether the network is live"),
 ITEM("circuit-status", events, "List of current circuits originating here."),
 ITEM("stream-status", events,"List of current streams."),
 ITEM("orconn-status", events, "A list of current OR connections."),
 ITEM("dormant", misc,
      "Is Tor dormant (not building circuits because it's idle)?"),
 PREFIX("address-mappings/", events, NULL),
 DOC("address-mappings/all", "Current address mappings."),
 DOC("address-mappings/cache", "Current cached DNS replies."),
 DOC("address-mappings/config",
     "Current address mappings from configuration."),
 DOC("address-mappings/control", "Current address mappings from controller."),
 PREFIX("status/", events, NULL),
 DOC("status/circuit-established",
     "Whether we think client functionality is working."),
 DOC("status/enough-dir-info",
     "Whether we have enough up-to-date directory information to build "
     "circuits."),
 DOC("status/bootstrap-phase",
     "The last bootstrap phase status event that Tor sent."),
 DOC("status/clients-seen",
     "Breakdown of client countries seen by a bridge."),
 DOC("status/fresh-relay-descs",
     "A fresh relay/ei descriptor pair for Tor's current state. Not stored."),
 DOC("status/version/recommended", "List of currently recommended versions."),
 DOC("status/version/current", "Status of the current version."),
 ITEM("address", misc, "IP address of this Tor host, if we can guess it."),
 ITEM("address/v4", misc,
      "IPv4 address of this Tor host, if we can guess it."),
 ITEM("address/v6", misc,
      "IPv6 address of this Tor host, if we can guess it."),
 ITEM("traffic/read", misc,"Bytes read since the process was started."),
 ITEM("traffic/written", misc,
      "Bytes written since the process was started."),
 ITEM("uptime", misc, "Uptime of the Tor daemon in seconds."),
 ITEM("process/pid", misc, "Process id belonging to the main tor process."),
 ITEM("process/uid", misc, "User id running the tor process."),
 ITEM("process/user", misc,
      "Username under which the tor process is running."),
 ITEM("process/descriptor-limit", misc, "File descriptor limit."),
 ITEM("limits/max-mem-in-queues", misc, "Actual limit on memory in queues"),
 PREFIX("desc-annotations/id/", dir, "Router annotations by hexdigest."),
 PREFIX("dir/server/", dir,"Router descriptors as retrieved from a DirPort."),
 PREFIX("dir/status/", dir,
        "v2 networkstatus docs as retrieved from a DirPort."),
 ITEM("dir/status-vote/current/consensus", dir,
      "v3 Networkstatus consensus as retrieved from a DirPort."),
 ITEM("dir/status-vote/current/consensus-microdesc", dir,
      "v3 Microdescriptor consensus as retrieved from a DirPort."),
 ITEM("exit-policy/default", policies,
      "The default value appended to the configured exit policy."),
 ITEM("exit-policy/reject-private/default", policies,
      "The default rules appended to the configured exit policy by"
      " ExitPolicyRejectPrivate."),
 ITEM("exit-policy/reject-private/relay", policies,
      "The relay-specific rules appended to the configured exit policy by"
      " ExitPolicyRejectPrivate and/or ExitPolicyRejectLocalInterfaces."),
 ITEM("exit-policy/full", policies, "The entire exit policy of onion router"),
 ITEM("exit-policy/ipv4", policies, "IPv4 parts of exit policy"),
 ITEM("exit-policy/ipv6", policies, "IPv6 parts of exit policy"),
 PREFIX("ip-to-country/", geoip, "Perform a GEOIP lookup"),
 ITEM("onions/current", onions,
      "Onion services owned by the current control connection."),
 ITEM("onions/detached", onions,
      "Onion services detached from the control connection."),
 ITEM("sr/current", sr, "Get current shared random value."),
 ITEM("sr/previous", sr, "Get previous shared random value."),
 PREFIX("stats/ntor/", rephist, "NTor circuit handshake stats."),
 ITEM("stats/ntor/assigned", rephist,
      "Assigned NTor circuit handshake stats."),
 ITEM("stats/ntor/requested", rephist,
      "Requested NTor circuit handshake stats."),
 PREFIX("stats/tap/", rephist, "TAP circuit handshake stats."),
 ITEM("stats/tap/assigned", rephist,
      "Assigned TAP circuit handshake stats."),
 ITEM("stats/tap/requested", rephist,
      "Requested TAP circuit handshake stats."),
 { NULL, NULL, NULL, 0 }
};

/** Allocate and return a list of recognized GETINFO options. */
static char *
list_getinfo_options(void)
{
 int i;
 smartlist_t *lines = smartlist_new();
 char *ans;
 for (i = 0; getinfo_items[i].varname; ++i) {
   if (!getinfo_items[i].desc)
     continue;

   smartlist_add_asprintf(lines, "%s%s -- %s\n",
                getinfo_items[i].varname,
                getinfo_items[i].is_prefix ? "*" : "",
                getinfo_items[i].desc);
 }
 smartlist_sort_strings(lines);

 ans = smartlist_join_strings(lines, "", 0, NULL);
 SMARTLIST_FOREACH(lines, char *, cp, tor_free(cp));
 smartlist_free(lines);

 return ans;
}

/** Lookup the 'getinfo' entry <b>question</b>, and return
* the answer in <b>*answer</b> (or NULL if key not recognized).
* Return 0 if success or unrecognized, or -1 if recognized but
* internal error. */
static int
handle_getinfo_helper(control_connection_t *control_conn,
                     const char *question, char **answer,
                     const char **err_out)
{
 int i;
 *answer = NULL; /* unrecognized key by default */

 for (i = 0; getinfo_items[i].varname; ++i) {
   int match;
   if (getinfo_items[i].is_prefix)
     match = !strcmpstart(question, getinfo_items[i].varname);
   else
     match = !strcmp(question, getinfo_items[i].varname);
   if (match) {
     tor_assert(getinfo_items[i].fn);
     return getinfo_items[i].fn(control_conn, question, answer, err_out);
   }
 }

 return 0; /* unrecognized */
}

const control_cmd_syntax_t getinfo_syntax = {
 .max_args = UINT_MAX,
};

/** Called when we receive a GETINFO command.  Try to fetch all requested
* information, and reply with information or error message. */
int
handle_control_getinfo(control_connection_t *conn,
                      const control_cmd_args_t *args)
{
 const smartlist_t *questions = args->args;
 smartlist_t *answers = smartlist_new();
 smartlist_t *unrecognized = smartlist_new();
 char *ans = NULL;

 SMARTLIST_FOREACH_BEGIN(questions, const char *, q) {
   const char *errmsg = NULL;

   if (handle_getinfo_helper(conn, q, &ans, &errmsg) < 0) {
     if (!errmsg)
       errmsg = "Internal error";
     control_write_endreply(conn, 551, errmsg);
     goto done;
   }
   if (!ans) {
     if (errmsg) {
       /* use provided error message */
       control_reply_add_str(unrecognized, 552, errmsg);
     } else {
       /* use default error message */
       control_reply_add_printf(unrecognized, 552,
                                "Unrecognized key \"%s\"", q);
     }
   } else {
     control_reply_add_one_kv(answers, 250, KV_RAW, q, ans);
     tor_free(ans);
   }
 } SMARTLIST_FOREACH_END(q);

 control_reply_add_done(answers);

 if (smartlist_len(unrecognized)) {
   control_write_reply_lines(conn, unrecognized);
   /* If there were any unrecognized queries, don't write real answers */
   goto done;
 }

 control_write_reply_lines(conn, answers);

done:
 control_reply_free(answers);
 control_reply_free(unrecognized);

 return 0;
}