Outbindbindaddress variants for Exit and OR.

Allow separation of exit and relay traffic to different source IP
addresses (Ticket #17975). Written by Michael Sonntag.

changes/change_separate_exit_and_relay.txt

@@ -0,0 +1,2 @@
+- Minor features:
+    - Allow separation of exit and relay traffic to different source IP addresses (Ticket #17975). Written by Michael Sonntag.

doc/tor.1.txt

@@ -640,6 +640,20 @@ GENERAL OPTIONS
     This setting will be ignored for connections to the loopback addresses
     (127.0.0.0/8 and ::1).
 
+[[OutboundBindAddressOR]] **OutboundBindAddressOR** __IP__::
+    Make all outbound non-exit (=relay and other) connections originate from the IP 
+    address specified. This option overrides **OutboundBindAddress** for the same
+    IP version. This option may be used twice, once with an IPv4 address and once
+    with an IPv6 address. This setting will be ignored for connections to the
+    loopback addresses (127.0.0.0/8 and ::1).
+
+[[OutboundBindAddressExit]] **OutboundBindAddressExit** __IP__::
+    Make all outbound exit connections originate from the IP address specified. This
+    option overrides **OutboundBindAddress** for the same IP version. This option
+    may be used twice, once with an IPv4 address and once with an IPv6 address. This
+    setting will be ignored for connections to the loopback addresses (127.0.0.0/8
+    and ::1).
+
 [[PidFile]] **PidFile** __FILE__::
     On startup, write our PID to FILE. On clean shutdown, remove
     FILE. Can not be changed while tor is running.

src/config/torrc.sample.in

@@ -95,7 +95,12 @@
 
 ## If you have multiple network interfaces, you can specify one for
 ## outgoing traffic to use.
-# OutboundBindAddress 10.0.0.5
+## OutboundBindAddressExit will be used for all exit traffic, while
+## OutboundBindAddressOR will be used for all other connections.
+## If you do not wish to differentiate, use OutboundBindAddress to
+## specify the same address for both in a single line.
+#OutboundBindAddressExit 10.0.0.4
+#OutboundBindAddressOR 10.0.0.5
 
 ## A handle for your relay, so people don't have to refer to it by key.
 ## Nicknames must be between 1 and 19 characters inclusive, and must

src/or/config.c

@@ -411,6 +411,8 @@ static config_var_t option_vars_[] = {
   V(ORListenAddress,             LINELIST, NULL),
   VPORT(ORPort),
   V(OutboundBindAddress,         LINELIST,   NULL),
+  V(OutboundBindAddressOR,       LINELIST,   NULL),
+  V(OutboundBindAddressExit,     LINELIST,   NULL),
 
   OBSOLETE("PathBiasDisableRate"),
   V(PathBiasCircThreshold,       INT,      "-1"),
@@ -7917,57 +7919,81 @@ getinfo_helper_config(control_connection_t *conn,
   return 0;
 }
 
+/* Check whether an address has already been set against the options
+ * depending on address family and destination type. Any exsting
+ * value will lead to a fail, even if it is the same value. If not
+ * set and not only validating, copy it into this location too.
+ * Returns 0 on success or -1 if this address is already set.
+ */
+static int
+verify_and_store_outbound_address(sa_family_t family, tor_addr_t *addr,
+       outbound_addr_t type, or_options_t *options, int validate_only)
+{
+  if (type<0 || type>=OUTBOUND_ADDR_MAX
+      || (family!=AF_INET && family!=AF_INET6)) {
+    return -1;
+  }
+  int fam_index=0;
+  if (family==AF_INET6) {
+    fam_index=1;
+  }
+  tor_addr_t *dest=&options->OutboundBindAddresses[type][fam_index];
+  if (!tor_addr_is_null(dest)) {
+    return -1;
+  }
+  if (!validate_only) {
+    tor_addr_copy(dest, addr);
+  }
+  return 0;
+}
+
+/* Parse a list of address lines for a specific destination type.
+ * Will store them into the options if not validate_only. If a
+ * problem occurs, a suitable error message is store in msg.
+ * Returns 0 on success or -1 if any address is already set.
+ */
+static int
+parse_outbound_address_lines(const config_line_t *lines, outbound_addr_t type,
+           or_options_t *options, int validate_only, char **msg)
+{
+  tor_addr_t addr;
+  sa_family_t family;
+  while (lines) {
+    family = tor_addr_parse(&addr, lines->value);
+    if (verify_and_store_outbound_address(family, &addr, type,
+                                 options, validate_only)) {
+      if (msg)
+        tor_asprintf(msg, "Multiple%s%s outbound bind addresses "
+                     "configured: %s",
+                     family==AF_INET?" IPv4":(family==AF_INET6?" IPv6":""),
+                     type==OUTBOUND_ADDR_OR?" OR":
+                     (type==OUTBOUND_ADDR_EXIT?" exit":""), lines->value);
+      return -1;
+    }
+    lines = lines->next;
+  }
+  return 0;
+}
+
 /** Parse outbound bind address option lines. If <b>validate_only</b>
- * is not 0 update OutboundBindAddressIPv4_ and
- * OutboundBindAddressIPv6_ in <b>options</b>. On failure, set
- * <b>msg</b> (if provided) to a newly allocated string containing a
- * description of the problem and return -1. */
+ * is not 0 update OutboundBindAddresses in <b>options</b>.
+ * Only one address can be set for any of these values.
+ * On failure, set <b>msg</b> (if provided) to a newly allocated string
+ * containing a description of the problem and return -1.
+ */
 static int
 parse_outbound_addresses(or_options_t *options, int validate_only, char **msg)
 {
-  const config_line_t *lines = options->OutboundBindAddress;
-  int found_v4 = 0, found_v6 = 0;
-
   if (!validate_only) {
-    memset(&options->OutboundBindAddressIPv4_, 0,
-           sizeof(options->OutboundBindAddressIPv4_));
-    memset(&options->OutboundBindAddressIPv6_, 0,
-           sizeof(options->OutboundBindAddressIPv6_));
-  }
-  while (lines) {
-    tor_addr_t addr, *dst_addr = NULL;
-    int af = tor_addr_parse(&addr, lines->value);
-    switch (af) {
-    case AF_INET:
-      if (found_v4) {
-        if (msg)
-          tor_asprintf(msg, "Multiple IPv4 outbound bind addresses "
-                       "configured: %s", lines->value);
-        return -1;
-      }
-      found_v4 = 1;
-      dst_addr = &options->OutboundBindAddressIPv4_;
-      break;
-    case AF_INET6:
-      if (found_v6) {
-        if (msg)
-          tor_asprintf(msg, "Multiple IPv6 outbound bind addresses "
-                       "configured: %s", lines->value);
-        return -1;
-      }
-      found_v6 = 1;
-      dst_addr = &options->OutboundBindAddressIPv6_;
-      break;
-    default:
-      if (msg)
-        tor_asprintf(msg, "Outbound bind address '%s' didn't parse.",
-                     lines->value);
-      return -1;
-    }
-    if (!validate_only)
-      tor_addr_copy(dst_addr, &addr);
-    lines = lines->next;
+    memset(&options->OutboundBindAddresses, 0,
+           sizeof(options->OutboundBindAddresses));
   }
+  parse_outbound_address_lines(options->OutboundBindAddress,
+                      OUTBOUND_ADDR_EXIT_AND_OR, options, validate_only, msg);
+  parse_outbound_address_lines(options->OutboundBindAddressOR,
+                      OUTBOUND_ADDR_OR, options, validate_only, msg);
+  parse_outbound_address_lines(options->OutboundBindAddressExit,
+                      OUTBOUND_ADDR_EXIT, options, validate_only, msg);
   return 0;
 }
 

src/or/connection.c

@@ -134,6 +134,8 @@ static int connection_read_https_proxy_response(connection_t *conn);
 static void connection_send_socks5_connect(connection_t *conn);
 static const char *proxy_type_to_string(int proxy_type);
 static int get_proxy_type(void);
+const tor_addr_t *conn_get_outbound_address(sa_family_t family,
+                  const or_options_t *options, unsigned int conn_type);
 
 /** The last addresses that our network interface seemed to have been
  * binding to.  We use this as one way to detect when our IP changes.
@@ -1771,7 +1773,7 @@ connection_connect_sockaddr,(connection_t *conn,
 
   /*
    * We've got the socket open; give the OOS handler a chance to check
-   * against configuured maximum socket number, but tell it no exhaustion
+   * against configured maximum socket number, but tell it no exhaustion
    * failure.
    */
   connection_check_oos(get_n_open_sockets(), 0);
@@ -1890,6 +1892,47 @@ connection_connect_log_client_use_ip_version(const connection_t *conn)
   }
 }
 
+/** Retrieve the outbound address depending on the protocol (IPv4 or IPv6)
+ * and the connection type (relay, exit, ...)
+ * Return a socket address or NULL in case nothing is configured.
+ **/
+const tor_addr_t *
+conn_get_outbound_address(sa_family_t family,
+             const or_options_t *options, unsigned int conn_type)
+{
+  const tor_addr_t *ext_addr = NULL;
+
+  int fam_index=0;
+  if (family==AF_INET6) {
+    fam_index=1;
+  }
+  // If an exit connection, use the exit address (if present)
+  if (conn_type == CONN_TYPE_EXIT) {
+    if (!tor_addr_is_null(
+        &options->OutboundBindAddresses[OUTBOUND_ADDR_EXIT][fam_index])) {
+      ext_addr = &options->OutboundBindAddresses[OUTBOUND_ADDR_EXIT]
+                 [fam_index];
+    } else if (!tor_addr_is_null(
+                 &options->OutboundBindAddresses[OUTBOUND_ADDR_EXIT_AND_OR]
+                 [fam_index])) {
+      ext_addr = &options->OutboundBindAddresses[OUTBOUND_ADDR_EXIT_AND_OR]
+                 [fam_index];
+    }
+  } else { // All non-exit connections
+    if (!tor_addr_is_null(
+           &options->OutboundBindAddresses[OUTBOUND_ADDR_OR][fam_index])) {
+      ext_addr = &options->OutboundBindAddresses[OUTBOUND_ADDR_OR]
+                 [fam_index];
+    } else if (!tor_addr_is_null(
+                 &options->OutboundBindAddresses[OUTBOUND_ADDR_EXIT_AND_OR]
+                 [fam_index])) {
+      ext_addr = &options->OutboundBindAddresses[OUTBOUND_ADDR_EXIT_AND_OR]
+                 [fam_index];
+    }
+  }
+  return ext_addr;
+}
+
 /** Take conn, make a nonblocking socket; try to connect to
  * addr:port (port arrives in *host order*). If fail, return -1 and if
  * applicable put your best guess about errno into *<b>socket_error</b>.
@@ -1911,26 +1954,15 @@ connection_connect(connection_t *conn, const char *address,
   struct sockaddr *bind_addr = NULL;
   struct sockaddr *dest_addr;
   int dest_addr_len, bind_addr_len = 0;
-  const or_options_t *options = get_options();
-  int protocol_family;
 
   /* Log if we didn't stick to ClientUseIPv4/6 or ClientPreferIPv6OR/DirPort
    */
   connection_connect_log_client_use_ip_version(conn);
 
-  if (tor_addr_family(addr) == AF_INET6)
-    protocol_family = PF_INET6;
-  else
-    protocol_family = PF_INET;
-
   if (!tor_addr_is_loopback(addr)) {
     const tor_addr_t *ext_addr = NULL;
-    if (protocol_family == AF_INET &&
-        !tor_addr_is_null(&options->OutboundBindAddressIPv4_))
-      ext_addr = &options->OutboundBindAddressIPv4_;
-    else if (protocol_family == AF_INET6 &&
-             !tor_addr_is_null(&options->OutboundBindAddressIPv6_))
-      ext_addr = &options->OutboundBindAddressIPv6_;
+    ext_addr = conn_get_outbound_address(tor_addr_family(addr), get_options(),
+                                         conn->type);
     if (ext_addr) {
       memset(&bind_addr_ss, 0, sizeof(bind_addr_ss));
       bind_addr_len = tor_addr_to_sockaddr(ext_addr, 0,

src/or/or.h

@@ -3545,6 +3545,12 @@ typedef struct routerset_t routerset_t;
  * to pick its own port. */
 #define CFG_AUTO_PORT 0xc4005e
 
+/** Enumeration of outbound address configuration types:
+ * Exit-only, OR-only, or both */
+typedef enum {OUTBOUND_ADDR_EXIT, OUTBOUND_ADDR_OR,
+              OUTBOUND_ADDR_EXIT_AND_OR,
+              OUTBOUND_ADDR_MAX} outbound_addr_t;
+
 /** Configuration options for a Tor process. */
 typedef struct {
   uint32_t magic_;
@@ -3628,10 +3634,14 @@ typedef struct {
   config_line_t *ControlListenAddress;
   /** Local address to bind outbound sockets */
   config_line_t *OutboundBindAddress;
-  /** IPv4 address derived from OutboundBindAddress. */
-  tor_addr_t OutboundBindAddressIPv4_;
-  /** IPv6 address derived from OutboundBindAddress. */
-  tor_addr_t OutboundBindAddressIPv6_;
+  /** Local address to bind outbound relay sockets */
+  config_line_t *OutboundBindAddressOR;
+  /** Local address to bind outbound exit sockets */
+  config_line_t *OutboundBindAddressExit;
+  /** Addresses derived from the various OutboundBindAddress lines.
+   * [][0] is IPv4, [][1] is IPv6
+   */
+  tor_addr_t OutboundBindAddresses[OUTBOUND_ADDR_MAX][2];
   /** Directory server only: which versions of
    * Tor should we tell users to run? */
   config_line_t *RecommendedVersions;

src/or/policies.c

@@ -2019,10 +2019,10 @@ policies_copy_ipv4h_to_smartlist(smartlist_t *addr_list, uint32_t ipv4h_addr)
   }
 }
 
-/** Helper function that adds copies of
- * or_options->OutboundBindAddressIPv[4|6]_ to a smartlist as tor_addr_t *, as
- * long as or_options is non-NULL, and the addresses are not
- * tor_addr_is_null(), by passing them to policies_add_addr_to_smartlist.
+/** Helper function that adds copies of or_options->OutboundBindAddresses
+ * to a smartlist as tor_addr_t *, as long as or_options is non-NULL, and
+ * the addresses are not tor_addr_is_null(), by passing them to
+ * policies_add_addr_to_smartlist.
  *
  * The caller is responsible for freeing all the tor_addr_t* in the smartlist.
  */
@@ -2031,10 +2031,14 @@ policies_copy_outbound_addresses_to_smartlist(smartlist_t *addr_list,
                                               const or_options_t *or_options)
 {
   if (or_options) {
+    for (int i=0;i<OUTBOUND_ADDR_MAX;i++) {
+      for (int j=0;j<2;j++) {
+        if (!tor_addr_is_null(&or_options->OutboundBindAddresses[i][j])) {
           policies_copy_addr_to_smartlist(addr_list,
-                                    &or_options->OutboundBindAddressIPv4_);
-    policies_copy_addr_to_smartlist(addr_list,
-                                    &or_options->OutboundBindAddressIPv6_);
+                          &or_options->OutboundBindAddresses[i][j]);
+        }
+      }
+    }
   }
 }
 
@@ -2051,10 +2055,10 @@ policies_copy_outbound_addresses_to_smartlist(smartlist_t *addr_list,
  *  - if ipv6_local_address is non-NULL, and not the null tor_addr_t, add it
  *    to the list of configured addresses.
  * If <b>or_options->ExitPolicyRejectLocalInterfaces</b> is true:
- *  - if or_options->OutboundBindAddressIPv4_ is not the null tor_addr_t, add
- *    it to the list of configured addresses.
- *  - if or_options->OutboundBindAddressIPv6_ is not the null tor_addr_t, add
- *    it to the list of configured addresses.
+ *  - if or_options->OutboundBindAddresses[][0] (=IPv4) is not the null
+ *    tor_addr_t, add it to the list of configured addresses.
+ *  - if or_options->OutboundBindAddresses[][1] (=IPv6) is not the null
+ *    tor_addr_t, add it to the list of configured addresses.
  *
  * If <b>or_options->BridgeRelay</b> is false, append entries of default
  * Tor exit policy into <b>result</b> smartlist.

src/test/test_policy.c

@@ -1083,8 +1083,12 @@ test_policies_getinfo_helper_policies(void *arg)
   append_exit_policy_string(&mock_my_routerinfo.exit_policy, "reject *6:*");
 
   mock_options.IPv6Exit = 1;
-  tor_addr_from_ipv4h(&mock_options.OutboundBindAddressIPv4_, TEST_IPV4_ADDR);
-  tor_addr_parse(&mock_options.OutboundBindAddressIPv6_, TEST_IPV6_ADDR);
+  tor_addr_from_ipv4h(
+      &mock_options.OutboundBindAddresses[OUTBOUND_ADDR_EXIT][0],
+      TEST_IPV4_ADDR);
+  tor_addr_parse(
+      &mock_options.OutboundBindAddresses[OUTBOUND_ADDR_EXIT][1],
+      TEST_IPV6_ADDR);
 
   mock_options.ExitPolicyRejectPrivate = 1;
   mock_options.ExitPolicyRejectLocalInterfaces = 1;