Move address map into its own file.

1 files changed, 958 insertions, 0 deletions

diff --git a/src/or/addressmap.c b/src/or/addressmap.c
new file mode 100644
index 000000000..fec83a7eb
--- /dev/null
+++ b/src/or/addressmap.c
@@ -0,0 +1,958 @@
+/* Copyright (c) 2001 Matej Pfajfar.
+ * Copyright (c) 2001-2004, Roger Dingledine.
+ * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
+ * Copyright (c) 2007-2012, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+
+#include "or.h"
+#include "addressmap.h"
+#include "circuituse.h"
+#include "config.h"
+#include "connection_edge.h"
+#include "control.h"
+#include "dns.h"
+#include "routerset.h"
+#include "nodelist.h"
+
+/** A client-side struct to remember requests to rewrite addresses
+ * to new addresses. These structs are stored in the hash table
+ * "addressmap" below.
+ *
+ * There are 5 ways to set an address mapping:
+ * - A MapAddress command from the controller [permanent]
+ * - An AddressMap directive in the torrc [permanent]
+ * - When a TrackHostExits torrc directive is triggered [temporary]
+ * - When a DNS resolve succeeds [temporary]
+ * - When a DNS resolve fails [temporary]
+ *
+ * When an addressmap request is made but one is already registered,
+ * the new one is replaced only if the currently registered one has
+ * no "new_address" (that is, it's in the process of DNS resolve),
+ * or if the new one is permanent (expires==0 or 1).
+ *
+ * (We overload the 'expires' field, using "0" for mappings set via
+ * the configuration file, "1" for mappings set from the control
+ * interface, and other values for DNS and TrackHostExit mappings that can
+ * expire.)
+ *
+ * A mapping may be 'wildcarded'.  If "src_wildcard" is true, then
+ * any address that ends with a . followed by the key for this entry will
+ * get remapped by it.  If "dst_wildcard" is also true, then only the
+ * matching suffix of such addresses will get replaced by new_address.
+ */
+typedef struct {
+  char *new_address;
+  time_t expires;
+  addressmap_entry_source_t source:3;
+  unsigned src_wildcard:1;
+  unsigned dst_wildcard:1;
+  short num_resolve_failures;
+} addressmap_entry_t;
+
+/** Entry for mapping addresses to which virtual address we mapped them to. */
+typedef struct {
+  char *ipv4_address;
+  char *hostname_address;
+} virtaddress_entry_t;
+
+/** A hash table to store client-side address rewrite instructions. */
+static strmap_t *addressmap=NULL;
+/**
+ * Table mapping addresses to which virtual address, if any, we
+ * assigned them to.
+ *
+ * We maintain the following invariant: if [A,B] is in
+ * virtaddress_reversemap, then B must be a virtual address, and [A,B]
+ * must be in addressmap.  We do not require that the converse hold:
+ * if it fails, then we could end up mapping two virtual addresses to
+ * the same address, which is no disaster.
+ **/
+static strmap_t *virtaddress_reversemap=NULL;
+
+/** Initialize addressmap. */
+void
+addressmap_init(void)
+{
+  addressmap = strmap_new();
+  virtaddress_reversemap = strmap_new();
+}
+
+/** Free the memory associated with the addressmap entry <b>_ent</b>. */
+static void
+addressmap_ent_free(void *_ent)
+{
+  addressmap_entry_t *ent;
+  if (!_ent)
+    return;
+
+  ent = _ent;
+  tor_free(ent->new_address);
+  tor_free(ent);
+}
+
+/** Free storage held by a virtaddress_entry_t* entry in <b>ent</b>. */
+static void
+addressmap_virtaddress_ent_free(void *_ent)
+{
+  virtaddress_entry_t *ent;
+  if (!_ent)
+    return;
+
+  ent = _ent;
+  tor_free(ent->ipv4_address);
+  tor_free(ent->hostname_address);
+  tor_free(ent);
+}
+
+/** Free storage held by a virtaddress_entry_t* entry in <b>ent</b>. */
+static void
+addressmap_virtaddress_remove(const char *address, addressmap_entry_t *ent)
+{
+  if (ent && ent->new_address &&
+      address_is_in_virtual_range(ent->new_address)) {
+    virtaddress_entry_t *ve =
+      strmap_get(virtaddress_reversemap, ent->new_address);
+    /*log_fn(LOG_NOTICE,"remove reverse mapping for %s",ent->new_address);*/
+    if (ve) {
+      if (!strcmp(address, ve->ipv4_address))
+        tor_free(ve->ipv4_address);
+      if (!strcmp(address, ve->hostname_address))
+        tor_free(ve->hostname_address);
+      if (!ve->ipv4_address && !ve->hostname_address) {
+        tor_free(ve);
+        strmap_remove(virtaddress_reversemap, ent->new_address);
+      }
+    }
+  }
+}
+
+/** Remove <b>ent</b> (which must be mapped to by <b>address</b>) from the
+ * client address maps. */
+static void
+addressmap_ent_remove(const char *address, addressmap_entry_t *ent)
+{
+  addressmap_virtaddress_remove(address, ent);
+  addressmap_ent_free(ent);
+}
+
+/** Unregister all TrackHostExits mappings from any address to
+ * *.exitname.exit. */
+void
+clear_trackexithost_mappings(const char *exitname)
+{
+  char *suffix = NULL;
+  if (!addressmap || !exitname)
+    return;
+  tor_asprintf(&suffix, ".%s.exit", exitname);
+  tor_strlower(suffix);
+
+  STRMAP_FOREACH_MODIFY(addressmap, address, addressmap_entry_t *, ent) {
+    if (ent->source == ADDRMAPSRC_TRACKEXIT &&
+        !strcmpend(ent->new_address, suffix)) {
+      addressmap_ent_remove(address, ent);
+      MAP_DEL_CURRENT(address);
+    }
+  } STRMAP_FOREACH_END;
+
+  tor_free(suffix);
+}
+
+/** Remove all TRACKEXIT mappings from the addressmap for which the target
+ * host is unknown or no longer allowed, or for which the source address
+ * is no longer in trackexithosts. */
+void
+addressmap_clear_excluded_trackexithosts(const or_options_t *options)
+{
+  const routerset_t *allow_nodes = options->ExitNodes;
+  const routerset_t *exclude_nodes = options->ExcludeExitNodesUnion_;
+
+  if (!addressmap)
+    return;
+  if (routerset_is_empty(allow_nodes))
+    allow_nodes = NULL;
+  if (allow_nodes == NULL && routerset_is_empty(exclude_nodes))
+    return;
+
+  STRMAP_FOREACH_MODIFY(addressmap, address, addressmap_entry_t *, ent) {
+    size_t len;
+    const char *target = ent->new_address, *dot;
+    char *nodename;
+    const node_t *node;
+
+    if (!target) {
+      /* DNS resolving in progress */
+      continue;
+    } else if (strcmpend(target, ".exit")) {
+      /* Not a .exit mapping */
+      continue;
+    } else if (ent->source != ADDRMAPSRC_TRACKEXIT) {
+      /* Not a trackexit mapping. */
+      continue;
+    }
+    len = strlen(target);
+    if (len < 6)
+      continue; /* malformed. */
+    dot = target + len - 6; /* dot now points to just before .exit */
+    while (dot > target && *dot != '.')
+      dot--;
+    if (*dot == '.') dot++;
+    nodename = tor_strndup(dot, len-5-(dot-target));;
+    node = node_get_by_nickname(nodename, 0);
+    tor_free(nodename);
+    if (!node ||
+        (allow_nodes && !routerset_contains_node(allow_nodes, node)) ||
+        routerset_contains_node(exclude_nodes, node) ||
+        !hostname_in_track_host_exits(options, address)) {
+      /* We don't know this one, or we want to be rid of it. */
+      addressmap_ent_remove(address, ent);
+      MAP_DEL_CURRENT(address);
+    }
+  } STRMAP_FOREACH_END;
+}
+
+/** Remove all AUTOMAP mappings from the addressmap for which the
+ * source address no longer matches AutomapHostsSuffixes, which is
+ * no longer allowed by AutomapHostsOnResolve, or for which the
+ * target address is no longer in the virtual network. */
+void
+addressmap_clear_invalid_automaps(const or_options_t *options)
+{
+  int clear_all = !options->AutomapHostsOnResolve;
+  const smartlist_t *suffixes = options->AutomapHostsSuffixes;
+
+  if (!addressmap)
+    return;
+
+  if (!suffixes)
+    clear_all = 1; /* This should be impossible, but let's be sure. */
+
+  STRMAP_FOREACH_MODIFY(addressmap, src_address, addressmap_entry_t *, ent) {
+    int remove = clear_all;
+    if (ent->source != ADDRMAPSRC_AUTOMAP)
+      continue; /* not an automap mapping. */
+
+    if (!remove) {
+      int suffix_found = 0;
+      SMARTLIST_FOREACH(suffixes, const char *, suffix, {
+          if (!strcasecmpend(src_address, suffix)) {
+            suffix_found = 1;
+            break;
+          }
+      });
+      if (!suffix_found)
+        remove = 1;
+    }
+
+    if (!remove && ! address_is_in_virtual_range(ent->new_address))
+      remove = 1;
+
+    if (remove) {
+      addressmap_ent_remove(src_address, ent);
+      MAP_DEL_CURRENT(src_address);
+    }
+  } STRMAP_FOREACH_END;
+}
+
+/** Remove all entries from the addressmap that were set via the
+ * configuration file or the command line. */
+void
+addressmap_clear_configured(void)
+{
+  addressmap_get_mappings(NULL, 0, 0, 0);
+}
+
+/** Remove all entries from the addressmap that are set to expire, ever. */
+void
+addressmap_clear_transient(void)
+{
+  addressmap_get_mappings(NULL, 2, TIME_MAX, 0);
+}
+
+/** Clean out entries from the addressmap cache that were
+ * added long enough ago that they are no longer valid.
+ */
+void
+addressmap_clean(time_t now)
+{
+  addressmap_get_mappings(NULL, 2, now, 0);
+}
+
+/** Free all the elements in the addressmap, and free the addressmap
+ * itself. */
+void
+addressmap_free_all(void)
+{
+  strmap_free(addressmap, addressmap_ent_free);
+  addressmap = NULL;
+
+  strmap_free(virtaddress_reversemap, addressmap_virtaddress_ent_free);
+  virtaddress_reversemap = NULL;
+}
+
+/** Try to find a match for AddressMap expressions that use
+ *  wildcard notation such as '*.c.d *.e.f' (so 'a.c.d' will map to 'a.e.f') or
+ *  '*.c.d a.b.c' (so 'a.c.d' will map to a.b.c).
+ *  Return the matching entry in AddressMap or NULL if no match is found.
+ *  For expressions such as '*.c.d *.e.f', truncate <b>address</b> 'a.c.d'
+ *  to 'a' before we return the matching AddressMap entry.
+ *
+ * This function does not handle the case where a pattern of the form "*.c.d"
+ * matches the address c.d -- that's done by the main addressmap_rewrite
+ * function.
+ */
+static addressmap_entry_t *
+addressmap_match_superdomains(char *address)
+{
+  addressmap_entry_t *val;
+  char *cp;
+
+  cp = address;
+  while ((cp = strchr(cp, '.'))) {
+    /* cp now points to a suffix of address that begins with a . */
+    val = strmap_get_lc(addressmap, cp+1);
+    if (val && val->src_wildcard) {
+      if (val->dst_wildcard)
+        *cp = '\0';
+      return val;
+    }
+    ++cp;
+  }
+  return NULL;
+}
+
+/** Look at address, and rewrite it until it doesn't want any
+ * more rewrites; but don't get into an infinite loop.
+ * Don't write more than maxlen chars into address.  Return true if the
+ * address changed; false otherwise.  Set *<b>expires_out</b> to the
+ * expiry time of the result, or to <b>time_max</b> if the result does
+ * not expire.
+ *
+ * If <b>exit_source_out</b> is non-null, we set it as follows.  If we the
+ * address starts out as a non-exit address, and we remap it to an .exit
+ * address at any point, then set *<b>exit_source_out</b> to the
+ * address_entry_source_t of the first such rule.  Set *<b>exit_source_out</b>
+ * to ADDRMAPSRC_NONE if there is no such rewrite, or if the original address
+ * was a .exit.
+ */
+int
+addressmap_rewrite(char *address, size_t maxlen, time_t *expires_out,
+                   addressmap_entry_source_t *exit_source_out)
+{
+  addressmap_entry_t *ent;
+  int rewrites;
+  time_t expires = TIME_MAX;
+  addressmap_entry_source_t exit_source = ADDRMAPSRC_NONE;
+  char *addr_orig = tor_strdup(address);
+  char *log_addr_orig = NULL;
+
+  for (rewrites = 0; rewrites < 16; rewrites++) {
+    int exact_match = 0;
+    log_addr_orig = tor_strdup(escaped_safe_str_client(address));
+
+    ent = strmap_get(addressmap, address);
+
+    if (!ent || !ent->new_address) {
+      ent = addressmap_match_superdomains(address);
+    } else {
+      if (ent->src_wildcard && !ent->dst_wildcard &&
+          !strcasecmp(address, ent->new_address)) {
+        /* This is a rule like *.example.com example.com, and we just got
+         * "example.com" */
+        goto done;
+      }
+
+      exact_match = 1;
+    }
+
+    if (!ent || !ent->new_address) {
+      goto done;
+    }
+
+    if (ent->dst_wildcard && !exact_match) {
+      strlcat(address, ".", maxlen);
+      strlcat(address, ent->new_address, maxlen);
+    } else {
+      strlcpy(address, ent->new_address, maxlen);
+    }
+
+    if (!strcmpend(address, ".exit") &&
+        strcmpend(addr_orig, ".exit") &&
+        exit_source == ADDRMAPSRC_NONE) {
+      exit_source = ent->source;
+    }
+
+    log_info(LD_APP, "Addressmap: rewriting %s to %s",
+             log_addr_orig, escaped_safe_str_client(address));
+    if (ent->expires > 1 && ent->expires < expires)
+      expires = ent->expires;
+
+    tor_free(log_addr_orig);
+  }
+  log_warn(LD_CONFIG,
+           "Loop detected: we've rewritten %s 16 times! Using it as-is.",
+           escaped_safe_str_client(address));
+  /* it's fine to rewrite a rewrite, but don't loop forever */
+
+ done:
+  tor_free(addr_orig);
+  tor_free(log_addr_orig);
+  if (exit_source_out)
+    *exit_source_out = exit_source;
+  if (expires_out)
+    *expires_out = TIME_MAX;
+  return (rewrites > 0);
+}
+
+/** If we have a cached reverse DNS entry for the address stored in the
+ * <b>maxlen</b>-byte buffer <b>address</b> (typically, a dotted quad) then
+ * rewrite to the cached value and return 1.  Otherwise return 0.  Set
+ * *<b>expires_out</b> to the expiry time of the result, or to <b>time_max</b>
+ * if the result does not expire. */
+int
+addressmap_rewrite_reverse(char *address, size_t maxlen, time_t *expires_out)
+{
+  char *s, *cp;
+  addressmap_entry_t *ent;
+  int r = 0;
+  tor_asprintf(&s, "REVERSE[%s]", address);
+  ent = strmap_get(addressmap, s);
+  if (ent) {
+    cp = tor_strdup(escaped_safe_str_client(ent->new_address));
+    log_info(LD_APP, "Rewrote reverse lookup %s -> %s",
+             escaped_safe_str_client(s), cp);
+    tor_free(cp);
+    strlcpy(address, ent->new_address, maxlen);
+    r = 1;
+  }
+
+  if (expires_out)
+    *expires_out = (ent && ent->expires > 1) ? ent->expires : TIME_MAX;
+
+  tor_free(s);
+  return r;
+}
+
+/** Return 1 if <b>address</b> is already registered, else return 0. If address
+ * is already registered, and <b>update_expires</b> is non-zero, then update
+ * the expiry time on the mapping with update_expires if it is a
+ * mapping created by TrackHostExits. */
+int
+addressmap_have_mapping(const char *address, int update_expiry)
+{
+  addressmap_entry_t *ent;
+  if (!(ent=strmap_get_lc(addressmap, address)))
+    return 0;
+  if (update_expiry && ent->source==ADDRMAPSRC_TRACKEXIT)
+    ent->expires=time(NULL) + update_expiry;
+  return 1;
+}
+
+/** Register a request to map <b>address</b> to <b>new_address</b>,
+ * which will expire on <b>expires</b> (or 0 if never expires from
+ * config file, 1 if never expires from controller, 2 if never expires
+ * (virtual address mapping) from the controller.)
+ *
+ * <b>new_address</b> should be a newly dup'ed string, which we'll use or
+ * free as appropriate. We will leave address alone.
+ *
+ * If <b>wildcard_addr</b> is true, then the mapping will match any address
+ * equal to <b>address</b>, or any address ending with a period followed by
+ * <b>address</b>.  If <b>wildcard_addr</b> and <b>wildcard_new_addr</b> are
+ * both true, the mapping will rewrite addresses that end with
+ * ".<b>address</b>" into ones that end with ".<b>new_address</b>."
+ *
+ * If <b>new_address</b> is NULL, or <b>new_address</b> is equal to
+ * <b>address</b> and <b>wildcard_addr</b> is equal to
+ * <b>wildcard_new_addr</b>, remove any mappings that exist from
+ * <b>address</b>.
+ *
+ *
+ * It is an error to set <b>wildcard_new_addr</b> if <b>wildcard_addr</b> is
+ * not set. */
+void
+addressmap_register(const char *address, char *new_address, time_t expires,
+                    addressmap_entry_source_t source,
+                    const int wildcard_addr,
+                    const int wildcard_new_addr)
+{
+  addressmap_entry_t *ent;
+
+  if (wildcard_new_addr)
+    tor_assert(wildcard_addr);
+
+  ent = strmap_get(addressmap, address);
+  if (!new_address || (!strcasecmp(address,new_address) &&
+                       wildcard_addr == wildcard_new_addr)) {
+    /* Remove the mapping, if any. */
+    tor_free(new_address);
+    if (ent) {
+      addressmap_ent_remove(address,ent);
+      strmap_remove(addressmap, address);
+    }
+    return;
+  }
+  if (!ent) { /* make a new one and register it */
+    ent = tor_malloc_zero(sizeof(addressmap_entry_t));
+    strmap_set(addressmap, address, ent);
+  } else if (ent->new_address) { /* we need to clean up the old mapping. */
+    if (expires > 1) {
+      log_info(LD_APP,"Temporary addressmap ('%s' to '%s') not performed, "
+               "since it's already mapped to '%s'",
+      safe_str_client(address),
+      safe_str_client(new_address),
+      safe_str_client(ent->new_address));
+      tor_free(new_address);
+      return;
+    }
+    if (address_is_in_virtual_range(ent->new_address) &&
+        expires != 2) {
+      /* XXX This isn't the perfect test; we want to avoid removing
+       * mappings set from the control interface _as virtual mapping */
+      addressmap_virtaddress_remove(address, ent);
+    }
+    tor_free(ent->new_address);
+  } /* else { we have an in-progress resolve with no mapping. } */
+
+  ent->new_address = new_address;
+  ent->expires = expires==2 ? 1 : expires;
+  ent->num_resolve_failures = 0;
+  ent->source = source;
+  ent->src_wildcard = wildcard_addr ? 1 : 0;
+  ent->dst_wildcard = wildcard_new_addr ? 1 : 0;
+
+  log_info(LD_CONFIG, "Addressmap: (re)mapped '%s' to '%s'",
+           safe_str_client(address),
+           safe_str_client(ent->new_address));
+  control_event_address_mapped(address, ent->new_address, expires, NULL);
+}
+
+/** An attempt to resolve <b>address</b> failed at some OR.
+ * Increment the number of resolve failures we have on record
+ * for it, and then return that number.
+ */
+int
+client_dns_incr_failures(const char *address)
+{
+  addressmap_entry_t *ent = strmap_get(addressmap, address);
+  if (!ent) {
+    ent = tor_malloc_zero(sizeof(addressmap_entry_t));
+    ent->expires = time(NULL) + MAX_DNS_ENTRY_AGE;
+    strmap_set(addressmap,address,ent);
+  }
+  if (ent->num_resolve_failures < SHORT_MAX)
+    ++ent->num_resolve_failures; /* don't overflow */
+  log_info(LD_APP, "Address %s now has %d resolve failures.",
+           safe_str_client(address),
+           ent->num_resolve_failures);
+  return ent->num_resolve_failures;
+}
+
+/** If <b>address</b> is in the client DNS addressmap, reset
+ * the number of resolve failures we have on record for it.
+ * This is used when we fail a stream because it won't resolve:
+ * otherwise future attempts on that address will only try once.
+ */
+void
+client_dns_clear_failures(const char *address)
+{
+  addressmap_entry_t *ent = strmap_get(addressmap, address);
+  if (ent)
+    ent->num_resolve_failures = 0;
+}
+
+/** Record the fact that <b>address</b> resolved to <b>name</b>.
+ * We can now use this in subsequent streams via addressmap_rewrite()
+ * so we can more correctly choose an exit that will allow <b>address</b>.
+ *
+ * If <b>exitname</b> is defined, then append the addresses with
+ * ".exitname.exit" before registering the mapping.
+ *
+ * If <b>ttl</b> is nonnegative, the mapping will be valid for
+ * <b>ttl</b>seconds; otherwise, we use the default.
+ */
+static void
+client_dns_set_addressmap_impl(const char *address, const char *name,
+                               const char *exitname,
+                               int ttl)
+{
+  /* <address>.<hex or nickname>.exit\0  or just  <address>\0 */
+  char extendedaddress[MAX_SOCKS_ADDR_LEN+MAX_VERBOSE_NICKNAME_LEN+10];
+  /* 123.123.123.123.<hex or nickname>.exit\0  or just  123.123.123.123\0 */
+  char extendedval[INET_NTOA_BUF_LEN+MAX_VERBOSE_NICKNAME_LEN+10];
+
+  tor_assert(address);
+  tor_assert(name);
+
+  if (ttl<0)
+    ttl = DEFAULT_DNS_TTL;
+  else
+    ttl = dns_clip_ttl(ttl);
+
+  if (exitname) {
+    /* XXXX fails to ever get attempts to get an exit address of
+     * google.com.digest[=~]nickname.exit; we need a syntax for this that
+     * won't make strict RFC952-compliant applications (like us) barf. */
+    tor_snprintf(extendedaddress, sizeof(extendedaddress),
+                 "%s.%s.exit", address, exitname);
+    tor_snprintf(extendedval, sizeof(extendedval),
+                 "%s.%s.exit", name, exitname);
+  } else {
+    tor_snprintf(extendedaddress, sizeof(extendedaddress),
+                 "%s", address);
+    tor_snprintf(extendedval, sizeof(extendedval),
+                 "%s", name);
+  }
+  addressmap_register(extendedaddress, tor_strdup(extendedval),
+                      time(NULL) + ttl, ADDRMAPSRC_DNS, 0, 0);
+}
+
+/** Record the fact that <b>address</b> resolved to <b>val</b>.
+ * We can now use this in subsequent streams via addressmap_rewrite()
+ * so we can more correctly choose an exit that will allow <b>address</b>.
+ *
+ * If <b>exitname</b> is defined, then append the addresses with
+ * ".exitname.exit" before registering the mapping.
+ *
+ * If <b>ttl</b> is nonnegative, the mapping will be valid for
+ * <b>ttl</b>seconds; otherwise, we use the default.
+ */
+void
+client_dns_set_addressmap(const char *address, uint32_t val,
+                          const char *exitname,
+                          int ttl)
+{
+  struct in_addr in;
+  char valbuf[INET_NTOA_BUF_LEN];
+
+  tor_assert(address);
+
+  if (tor_inet_aton(address, &in))
+    return; /* If address was an IP address already, don't add a mapping. */
+  in.s_addr = htonl(val);
+  tor_inet_ntoa(&in,valbuf,sizeof(valbuf));
+
+  client_dns_set_addressmap_impl(address, valbuf, exitname, ttl);
+}
+
+/** Add a cache entry noting that <b>address</b> (ordinarily a dotted quad)
+ * resolved via a RESOLVE_PTR request to the hostname <b>v</b>.
+ *
+ * If <b>exitname</b> is defined, then append the addresses with
+ * ".exitname.exit" before registering the mapping.
+ *
+ * If <b>ttl</b> is nonnegative, the mapping will be valid for
+ * <b>ttl</b>seconds; otherwise, we use the default.
+ */
+void
+client_dns_set_reverse_addressmap(const char *address, const char *v,
+                                  const char *exitname,
+                                  int ttl)
+{
+  char *s = NULL;
+  tor_asprintf(&s, "REVERSE[%s]", address);
+  client_dns_set_addressmap_impl(s, v, exitname, ttl);
+  tor_free(s);
+}
+
+/* By default, we hand out 127.192.0.1 through 127.254.254.254.
+ * These addresses should map to localhost, so even if the
+ * application accidentally tried to connect to them directly (not
+ * via Tor), it wouldn't get too far astray.
+ *
+ * These options are configured by parse_virtual_addr_network().
+ */
+/** Which network should we use for virtual IPv4 addresses?  Only the first
+ * bits of this value are fixed. */
+static uint32_t virtual_addr_network = 0x7fc00000u;
+/** How many bits of <b>virtual_addr_network</b> are fixed? */
+static maskbits_t virtual_addr_netmask_bits = 10;
+/** What's the next virtual address we will hand out? */
+static uint32_t next_virtual_addr    = 0x7fc00000u;
+
+/** Read a netmask of the form 127.192.0.0/10 from "val", and check whether
+ * it's a valid set of virtual addresses to hand out in response to MAPADDRESS
+ * requests.  Return 0 on success; set *msg (if provided) to a newly allocated
+ * string and return -1 on failure.  If validate_only is false, sets the
+ * actual virtual address range to the parsed value. */
+int
+parse_virtual_addr_network(const char *val, int validate_only,
+                           char **msg)
+{
+  uint32_t addr;
+  uint16_t port_min, port_max;
+  maskbits_t bits;
+
+  if (parse_addr_and_port_range(val, &addr, &bits, &port_min, &port_max)) {
+    if (msg) *msg = tor_strdup("Error parsing VirtualAddressNetwork");
+    return -1;
+  }
+
+  if (port_min != 1 || port_max != 65535) {
+    if (msg) *msg = tor_strdup("Can't specify ports on VirtualAddressNetwork");
+    return -1;
+  }
+
+  if (bits > 16) {
+    if (msg) *msg = tor_strdup("VirtualAddressNetwork expects a /16 "
+                               "network or larger");
+    return -1;
+  }
+
+  if (validate_only)
+    return 0;
+
+  virtual_addr_network = (uint32_t)( addr & (0xfffffffful << (32-bits)) );
+  virtual_addr_netmask_bits = bits;
+
+  if (addr_mask_cmp_bits(next_virtual_addr, addr, bits))
+    next_virtual_addr = addr;
+
+  return 0;
+}
+
+/**
+ * Return true iff <b>addr</b> is likely to have been returned by
+ * client_dns_get_unused_address.
+ **/
+int
+address_is_in_virtual_range(const char *address)
+{
+  struct in_addr in;
+  tor_assert(address);
+  if (!strcasecmpend(address, ".virtual")) {
+    return 1;
+  } else if (tor_inet_aton(address, &in)) {
+    uint32_t addr = ntohl(in.s_addr);
+    if (!addr_mask_cmp_bits(addr, virtual_addr_network,
+                            virtual_addr_netmask_bits))
+      return 1;
+  }
+  return 0;
+}
+
+/** Increment the value of next_virtual_addr; reset it to the start of the
+ * virtual address range if it wraps around.
+ */
+static INLINE void
+increment_virtual_addr(void)
+{
+  ++next_virtual_addr;
+  if (addr_mask_cmp_bits(next_virtual_addr, virtual_addr_network,
+                         virtual_addr_netmask_bits))
+    next_virtual_addr = virtual_addr_network;
+}
+
+/** Return a newly allocated string holding an address of <b>type</b>
+ * (one of RESOLVED_TYPE_{IPV4|HOSTNAME}) that has not yet been mapped,
+ * and that is very unlikely to be the address of any real host.
+ *
+ * May return NULL if we have run out of virtual addresses.
+ */
+static char *
+addressmap_get_virtual_address(int type)
+{
+  char buf[64];
+  tor_assert(addressmap);
+
+  if (type == RESOLVED_TYPE_HOSTNAME) {
+    char rand[10];
+    do {
+      crypto_rand(rand, sizeof(rand));
+      base32_encode(buf,sizeof(buf),rand,sizeof(rand));
+      strlcat(buf, ".virtual", sizeof(buf));
+    } while (strmap_get(addressmap, buf));
+    return tor_strdup(buf);
+  } else if (type == RESOLVED_TYPE_IPV4) {
+    // This is an imperfect estimate of how many addresses are available, but
+    // that's ok.
+    struct in_addr in;
+    uint32_t available = 1u << (32-virtual_addr_netmask_bits);
+    while (available) {
+      /* Don't hand out any .0 or .255 address. */
+      while ((next_virtual_addr & 0xff) == 0 ||
+             (next_virtual_addr & 0xff) == 0xff) {
+        increment_virtual_addr();
+        if (! --available) {
+          log_warn(LD_CONFIG, "Ran out of virtual addresses!");
+          return NULL;
+        }
+      }
+      in.s_addr = htonl(next_virtual_addr);
+      tor_inet_ntoa(&in, buf, sizeof(buf));
+      if (!strmap_get(addressmap, buf)) {
+        increment_virtual_addr();
+        break;
+      }
+
+      increment_virtual_addr();
+      --available;
+      // log_info(LD_CONFIG, "%d addrs available", (int)available);
+      if (! available) {
+        log_warn(LD_CONFIG, "Ran out of virtual addresses!");
+        return NULL;
+      }
+    }
+    return tor_strdup(buf);
+  } else {
+    log_warn(LD_BUG, "Called with unsupported address type (%d)", type);
+    return NULL;
+  }
+}
+
+/** A controller has requested that we map some address of type
+ * <b>type</b> to the address <b>new_address</b>.  Choose an address
+ * that is unlikely to be used, and map it, and return it in a newly
+ * allocated string.  If another address of the same type is already
+ * mapped to <b>new_address</b>, try to return a copy of that address.
+ *
+ * The string in <b>new_address</b> may be freed or inserted into a map
+ * as appropriate.  May return NULL if are out of virtual addresses.
+ **/
+const char *
+addressmap_register_virtual_address(int type, char *new_address)
+{
+  char **addrp;
+  virtaddress_entry_t *vent;
+  int vent_needs_to_be_added = 0;
+
+  tor_assert(new_address);
+  tor_assert(addressmap);
+  tor_assert(virtaddress_reversemap);
+
+  vent = strmap_get(virtaddress_reversemap, new_address);
+  if (!vent) {
+    vent = tor_malloc_zero(sizeof(virtaddress_entry_t));
+    vent_needs_to_be_added = 1;
+  }
+
+  addrp = (type == RESOLVED_TYPE_IPV4) ?
+    &vent->ipv4_address : &vent->hostname_address;
+  if (*addrp) {
+    addressmap_entry_t *ent = strmap_get(addressmap, *addrp);
+    if (ent && ent->new_address &&
+        !strcasecmp(new_address, ent->new_address)) {
+      tor_free(new_address);
+      tor_assert(!vent_needs_to_be_added);
+      return tor_strdup(*addrp);
+    } else
+      log_warn(LD_BUG,
+               "Internal confusion: I thought that '%s' was mapped to by "
+               "'%s', but '%s' really maps to '%s'. This is a harmless bug.",
+               safe_str_client(new_address),
+               safe_str_client(*addrp),
+               safe_str_client(*addrp),
+               ent?safe_str_client(ent->new_address):"(nothing)");
+  }
+
+  tor_free(*addrp);
+  *addrp = addressmap_get_virtual_address(type);
+  if (!*addrp) {
+    tor_free(vent);
+    tor_free(new_address);
+    return NULL;
+  }
+  log_info(LD_APP, "Registering map from %s to %s", *addrp, new_address);
+  if (vent_needs_to_be_added)
+    strmap_set(virtaddress_reversemap, new_address, vent);
+  addressmap_register(*addrp, new_address, 2, ADDRMAPSRC_AUTOMAP, 0, 0);
+
+#if 0
+  {
+    /* Try to catch possible bugs */
+    addressmap_entry_t *ent;
+    ent = strmap_get(addressmap, *addrp);
+    tor_assert(ent);
+    tor_assert(!strcasecmp(ent->new_address,new_address));
+    vent = strmap_get(virtaddress_reversemap, new_address);
+    tor_assert(vent);
+    tor_assert(!strcasecmp(*addrp,
+                           (type == RESOLVED_TYPE_IPV4) ?
+                           vent->ipv4_address : vent->hostname_address));
+    log_info(LD_APP, "Map from %s to %s okay.",
+             safe_str_client(*addrp),
+             safe_str_client(new_address));
+  }
+#endif
+
+  return *addrp;
+}
+
+/** Return 1 if <b>address</b> has funny characters in it like colons. Return
+ * 0 if it's fine, or if we're configured to allow it anyway.  <b>client</b>
+ * should be true if we're using this address as a client; false if we're
+ * using it as a server.
+ */
+int
+address_is_invalid_destination(const char *address, int client)
+{
+  if (client) {
+    if (get_options()->AllowNonRFC953Hostnames)
+      return 0;
+  } else {
+    if (get_options()->ServerDNSAllowNonRFC953Hostnames)
+      return 0;
+  }
+
+  while (*address) {
+    if (TOR_ISALNUM(*address) ||
+        *address == '-' ||
+        *address == '.' ||
+        *address == '_') /* Underscore is not allowed, but Windows does it
+                          * sometimes, just to thumb its nose at the IETF. */
+      ++address;
+    else
+      return 1;
+  }
+  return 0;
+}
+
+/** Iterate over all address mappings which have expiry times between
+ * min_expires and max_expires, inclusive.  If sl is provided, add an
+ * "old-addr new-addr expiry" string to sl for each mapping, omitting
+ * the expiry time if want_expiry is false. If sl is NULL, remove the
+ * mappings.
+ */
+void
+addressmap_get_mappings(smartlist_t *sl, time_t min_expires,
+                        time_t max_expires, int want_expiry)
+{
+   strmap_iter_t *iter;
+   const char *key;
+   void *val_;
+   addressmap_entry_t *val;
+
+   if (!addressmap)
+     addressmap_init();
+
+   for (iter = strmap_iter_init(addressmap); !strmap_iter_done(iter); ) {
+     strmap_iter_get(iter, &key, &val_);
+     val = val_;
+     if (val->expires >= min_expires && val->expires <= max_expires) {
+       if (!sl) {
+         iter = strmap_iter_next_rmv(addressmap,iter);
+         addressmap_ent_remove(key, val);
+         continue;
+       } else if (val->new_address) {
+         const char *src_wc = val->src_wildcard ? "*." : "";
+         const char *dst_wc = val->dst_wildcard ? "*." : "";
+         if (want_expiry) {
+           if (val->expires < 3 || val->expires == TIME_MAX)
+             smartlist_add_asprintf(sl, "%s%s %s%s NEVER",
+                                    src_wc, key, dst_wc, val->new_address);
+           else {
+             char time[ISO_TIME_LEN+1];
+             format_iso_time(time, val->expires);
+             smartlist_add_asprintf(sl, "%s%s %s%s \"%s\"",
+                                    src_wc, key, dst_wc, val->new_address,
+                                    time);
+           }
+         } else {
+           smartlist_add_asprintf(sl, "%s%s %s%s",
+                                  src_wc, key, dst_wc, val->new_address);
+         }
+       }
+     }
+     iter = strmap_iter_next(addressmap,iter);
+   }
+}
+