Merge remote-tracking branch 'asn2/bug3656'

Conflicts:
	src/common/util.c
	src/common/util.h
	src/or/config.h
	src/or/main.c
	src/test/test_util.c

10 files changed, 1816 insertions, 81 deletions

diff --git a/src/or/Makefile.am b/src/or/Makefile.am
index e2a1b6d649..67adf504df 100644
--- a/src/or/Makefile.am
+++ b/src/or/Makefile.am
@@ -39,6 +39,7 @@ libtor_a_SOURCES = \
 	networkstatus.c				\
 	nodelist.c				\
 	onion.c					\
+	transports.c            \
 	policies.c				\
 	reasons.c				\
 	relay.c					\
@@ -104,6 +105,7 @@ noinst_HEADERS = \
 	ntmain.h				\
 	onion.h					\
 	or.h					\
+	transports.h            \
 	policies.h				\
 	reasons.h				\
 	relay.h					\
diff --git a/src/or/circuitbuild.c b/src/or/circuitbuild.c
index 36f7dad1bc..c4b697c9a6 100644
--- a/src/or/circuitbuild.c
+++ b/src/or/circuitbuild.c
@@ -26,6 +26,7 @@
 #include "nodelist.h"
 #include "onion.h"
 #include "policies.h"
+#include "transports.h"
 #include "relay.h"
 #include "rephist.h"
 #include "router.h"
@@ -123,8 +124,6 @@ static int onion_append_hop(crypt_path_t **head_ptr, extend_info_t *choice);
 
 static void entry_guards_changed(void);
 
-static const transport_t *transport_get_by_name(const char *name);
-static void transport_free(transport_t *transport);
 static void bridge_free(bridge_info_t *bridge);
 
 /**
@@ -4595,6 +4594,32 @@ bridge_free(bridge_info_t *bridge)
 /** A list of pluggable transports found in torrc. */
 static smartlist_t *transport_list = NULL;
 
+/** Mark every entry of the transport list to be removed on our next call to
+ * sweep_transport_list unless it has first been un-marked. */
+void
+mark_transport_list(void)
+{
+  if (!transport_list)
+    transport_list = smartlist_create();
+  SMARTLIST_FOREACH(transport_list, transport_t *, t,
+                    t->marked_for_removal = 1);
+}
+
+/** Remove every entry of the transport list that was marked with
+ * mark_transport_list if it has not subsequently been un-marked. */
+void
+sweep_transport_list(void)
+{
+  if (!transport_list)
+    transport_list = smartlist_create();
+  SMARTLIST_FOREACH_BEGIN(transport_list, transport_t *, t) {
+    if (t->marked_for_removal) {
+      SMARTLIST_DEL_CURRENT(transport_list, t);
+      transport_free(t);
+    }
+  } SMARTLIST_FOREACH_END(t);
+}
+
 /** Initialize the pluggable transports list to empty, creating it if
  *  needed. */
 void
@@ -4607,7 +4632,7 @@ clear_transport_list(void)
 }
 
 /** Free the pluggable transport struct <b>transport</b>. */
-static void
+void
 transport_free(transport_t *transport)
 {
   if (!transport)
@@ -4619,7 +4644,7 @@ transport_free(transport_t *transport)
 
 /** Returns the transport in our transport list that has the name <b>name</b>.
  *  Else returns NULL. */
-static const transport_t *
+transport_t *
 transport_get_by_name(const char *name)
 {
   tor_assert(name);
@@ -4627,7 +4652,7 @@ transport_get_by_name(const char *name)
   if (!transport_list)
     return NULL;
 
-  SMARTLIST_FOREACH_BEGIN(transport_list, const transport_t *, transport) {
+  SMARTLIST_FOREACH_BEGIN(transport_list, transport_t *, transport) {
     if (!strcmp(transport->name, name))
       return transport;
   } SMARTLIST_FOREACH_END(transport);
@@ -4635,41 +4660,139 @@ transport_get_by_name(const char *name)
   return NULL;
 }
 
-/** Remember a new pluggable transport proxy at <b>addr</b>:<b>port</b>.
- *  <b>name</b> is set to the name of the protocol this proxy uses.
- *  <b>socks_ver</b> is set to the SOCKS version of the proxy.
- *
- *  Returns 0 on success, -1 on fail. */
-int
-transport_add_from_config(const tor_addr_t *addr, uint16_t port,
-                          const char *name, int socks_ver)
+/** Returns a transport_t struct for a transport proxy supporting the
+    protocol <b>name</b> listening at <b>addr</b>:<b>port</b> using
+    SOCKS version <b>socks_ver</b>. */
+transport_t *
+transport_create(const tor_addr_t *addr, uint16_t port,
+                 const char *name, int socks_ver)
 {
-  transport_t *t;
-
-  if (transport_get_by_name(name)) { /* check for duplicate names */
-    log_warn(LD_CONFIG, "More than one transport has '%s' as "
-             "its name.", name);
-    return -1;
-  }
+  transport_t *t = tor_malloc_zero(sizeof(transport_t));
 
-  t = tor_malloc_zero(sizeof(transport_t));
   tor_addr_copy(&t->addr, addr);
   t->port = port;
   t->name = tor_strdup(name);
   t->socks_version = socks_ver;
 
-  if (!transport_list)
-    transport_list = smartlist_create();
+  return t;
+}
+
+/** Resolve any conflicts that the insertion of transport <b>t</b>
+ *  might cause.
+ *  Return 0 if <b>t</b> is OK and should be registered, 1 if there is
+ *  a transport identical to <b>t</b> already registered and -1 if
+ *  <b>t</b> cannot be added due to conflicts. */
+static int
+transport_resolve_conflicts(transport_t *t)
+{
+  /* This is how we resolve transport conflicts:
+
+     If there is already a transport with the same name and addrport,
+     we either have duplicate torrc lines OR we are here post-HUP and
+     this transport was here pre-HUP as well. In any case, mark the
+     old transport so that it doesn't get removed and ignore the new
+     one. Our caller has to free the new transport so we return '1' to
+     signify this.
+
+     If there is already a transport with the same name but different
+     addrport:
+     * if it's marked for removal, it means that it either has a lower
+     priority than 't' in torrc (otherwise the mark would have been
+     cleared by the paragraph above), or it doesn't exist at all in
+     the post-HUP torrc. We destroy the old transport and register 't'.
+     * if it's *not* marked for removal, it means that it was newly
+     added in the post-HUP torrc or that it's of higher priority, in
+     this case we ignore 't'. */
+  transport_t *t_tmp = transport_get_by_name(t->name);
+  if (t_tmp) { /* same name */
+    if (tor_addr_eq(&t->addr, &t_tmp->addr) && (t->port == t_tmp->port)) {
+      /* same name *and* addrport */
+      t_tmp->marked_for_removal = 0;
+      return 1;
+    } else { /* same name but different addrport */
+      if (t_tmp->marked_for_removal) { /* marked for removal */
+        log_notice(LD_GENERAL, "You tried to add transport '%s' at '%s:%u' "
+                   "but there was already a transport marked for deletion at "
+                   "'%s:%u'. We deleted the old transport and registered the "
+                   "new one.", t->name, fmt_addr(&t->addr), t->port,
+                   fmt_addr(&t_tmp->addr), t_tmp->port);
+        smartlist_remove(transport_list, t_tmp);
+        transport_free(t_tmp);
+      } else { /* *not* marked for removal */
+        log_notice(LD_GENERAL, "You tried to add transport '%s' at '%s:%u' "
+                   "but the same transport already exists at '%s:%u'. "
+                   "Skipping.", t->name, fmt_addr(&t->addr), t->port,
+                   fmt_addr(&t_tmp->addr), t_tmp->port);
+        return -1;
+      }
+    }
+  }
 
-  smartlist_add(transport_list, t);
   return 0;
 }
 
-/** Warns the user of possible pluggable transport misconfiguration. */
-void
+/** Add transport <b>t</b> to the internal list of pluggable
+ *  transports.
+ *  Returns 0 if the transport was added correctly, 1 if the same
+ *  transport was already registered (in this case the caller must
+ *  free the transport) and -1 if there was an error.  */
+int
+transport_add(transport_t *t)
+{
+  int r;
+  tor_assert(t);
+
+  r = transport_resolve_conflicts(t);
+
+  switch (r) {
+  case 0: /* should register transport */
+    if (!transport_list)
+      transport_list = smartlist_create();
+    smartlist_add(transport_list, t);
+    return 0;
+  default: /* let our caller know the return code */
+    return r;
+  }
+}
+
+/** Remember a new pluggable transport proxy at <b>addr</b>:<b>port</b>.
+ *  <b>name</b> is set to the name of the protocol this proxy uses.
+ *  <b>socks_ver</b> is set to the SOCKS version of the proxy. */
+int
+transport_add_from_config(const tor_addr_t *addr, uint16_t port,
+                          const char *name, int socks_ver)
+{
+  transport_t *t = transport_create(addr, port, name, socks_ver);
+
+  int r = transport_add(t);
+
+  switch (r) {
+  case -1:
+  default:
+    log_notice(LD_GENERAL, "Could not add transport %s at %s:%u. Skipping.",
+               t->name, fmt_addr(&t->addr), t->port);
+    transport_free(t);
+    return -1;
+  case 1:
+    log_info(LD_GENERAL, "Succesfully registered transport %s at %s:%u.",
+             t->name, fmt_addr(&t->addr), t->port);
+     transport_free(t); /* falling */
+     return 0;
+  case 0:
+    log_info(LD_GENERAL, "Succesfully registered transport %s at %s:%u.",
+             t->name, fmt_addr(&t->addr), t->port);
+    return 0;
+  }
+}
+
+/** Warn the user of possible pluggable transport misconfiguration.
+ *  Return 0 if the validation happened, -1 if we should postpone the
+ *  validation. */
+int
 validate_pluggable_transports_config(void)
 {
-  if (bridge_list) {
+  /* Don't validate if managed proxies are not yet fully configured. */
+  if (bridge_list && !pt_proxies_configuration_pending()) {
     SMARTLIST_FOREACH_BEGIN(bridge_list, bridge_info_t *, b) {
       /* Skip bridges without transports. */
       if (!b->transport_name)
@@ -4683,6 +4806,10 @@ validate_pluggable_transports_config(void)
                  "corresponding ClientTransportPlugin line.",
                  b->transport_name);
     } SMARTLIST_FOREACH_END(b);
+
+    return 0;
+  } else {
+    return -1;
   }
 }
 
@@ -4913,6 +5040,11 @@ fetch_bridge_descriptors(const or_options_t *options, time_t now)
   if (!bridge_list)
     return;
 
+  /* If we still have unconfigured managed proxies, don't go and
+     connect to a bridge. */
+  if (pt_proxies_configuration_pending())
+    return;
+
   SMARTLIST_FOREACH_BEGIN(bridge_list, bridge_info_t *, bridge)
     {
       if (!download_status_is_ready(&bridge->fetch_status, now,
diff --git a/src/or/circuitbuild.h b/src/or/circuitbuild.h
index bb5c2eb0bf..1052db6153 100644
--- a/src/or/circuitbuild.h
+++ b/src/or/circuitbuild.h
@@ -22,6 +22,9 @@ typedef struct {
   tor_addr_t addr;
   /** Port of proxy */
   uint16_t port;
+  /** Boolean: We are re-parsing our transport list, and we are going to remove
+   * this one if we don't find it in the list of configured transports. */
+  unsigned marked_for_removal : 1;
 } transport_t;
 
 char *circuit_list_path(origin_circuit_t *circ, int verbose);
@@ -77,6 +80,9 @@ int getinfo_helper_entry_guards(control_connection_t *conn,
 
 void mark_bridge_list(void);
 void sweep_bridge_list(void);
+void mark_transport_list(void);
+void sweep_transport_list(void);
+
 int routerinfo_is_a_configured_bridge(const routerinfo_t *ri);
 int node_is_a_configured_bridge(const node_t *node);
 void learned_router_identity(const tor_addr_t *addr, uint16_t port,
@@ -142,9 +148,16 @@ int circuit_build_times_get_bw_scale(networkstatus_t *ns);
 void clear_transport_list(void);
 int transport_add_from_config(const tor_addr_t *addr, uint16_t port,
                                const char *name, int socks_ver);
+int transport_add(transport_t *t);
+void transport_free(transport_t *transport);
+transport_t *transport_create(const tor_addr_t *addr, uint16_t port,
+                                      const char *name, int socks_ver);
+
 int find_transport_by_bridge_addrport(const tor_addr_t *addr, uint16_t port,
                                       const transport_t **transport);
-void validate_pluggable_transports_config(void);
+transport_t *transport_get_by_name(const char *name);
+
+int validate_pluggable_transports_config(void);
 
 #endif
 
diff --git a/src/or/config.c b/src/or/config.c
index c44b09cad4..07f00822f2 100644
--- a/src/or/config.c
+++ b/src/or/config.c
@@ -33,7 +33,9 @@
 #include "rendservice.h"
 #include "rephist.h"
 #include "router.h"
+#include "util.h"
 #include "routerlist.h"
+#include "transports.h"
 #ifdef MS_WINDOWS
 #include <shlobj.h>
 #endif
@@ -301,6 +303,7 @@ static config_var_t _option_vars[] = {
   V(HTTPProxyAuthenticator,      STRING,   NULL),
   V(HTTPSProxy,                  STRING,   NULL),
   V(HTTPSProxyAuthenticator,     STRING,   NULL),
+  VAR("ServerTransportPlugin",   LINELIST, ServerTransportPlugin,  NULL),
   V(Socks4Proxy,                 STRING,   NULL),
   V(Socks5Proxy,                 STRING,   NULL),
   V(Socks5ProxyUsername,         STRING,   NULL),
@@ -477,6 +480,9 @@ static config_var_t _state_vars[] = {
   VAR("EntryGuardAddedBy",       LINELIST_S,  EntryGuards,             NULL),
   V(EntryGuards,                 LINELIST_V,  NULL),
 
+  VAR("TransportProxy",               LINELIST_S, TransportProxies, NULL),
+  V(TransportProxies,                 LINELIST_V, NULL),
+
   V(BWHistoryReadEnds,                ISOTIME,  NULL),
   V(BWHistoryReadInterval,            UINT,     "900"),
   V(BWHistoryReadValues,              CSV,      ""),
@@ -503,7 +509,6 @@ static config_var_t _state_vars[] = {
   V(CircuitBuildAbandonedCount,       UINT,     "0"),
   VAR("CircuitBuildTimeBin",          LINELIST_S, BuildtimeHistogram, NULL),
   VAR("BuildtimeHistogram",           LINELIST_V, BuildtimeHistogram, NULL),
-
   { NULL, CONFIG_TYPE_OBSOLETE, 0, NULL }
 };
 
@@ -581,6 +586,8 @@ static int check_nickname_list(const char *lst, const char *name, char **msg);
 
 static int parse_bridge_line(const char *line, int validate_only);
 static int parse_client_transport_line(const char *line, int validate_only);
+
+static int parse_server_transport_line(const char *line, int validate_only);
 static int parse_dir_server_line(const char *line,
                                  dirinfo_type_t required_type,
                                  int validate_only);
@@ -1276,18 +1283,6 @@ options_act(const or_options_t *old_options)
   if (consider_adding_dir_authorities(options, old_options) < 0)
     return -1;
 
-  clear_transport_list();
-  if (options->ClientTransportPlugin) {
-    for (cl = options->ClientTransportPlugin; cl; cl = cl->next) {
-      if (parse_client_transport_line(cl->value, 0)<0) {
-        log_warn(LD_BUG,
-                 "Previously validated ClientTransportPlugin line "
-                 "could not be added!");
-        return -1;
-      }
-    }
-  }
-
   if (options->Bridges) {
     mark_bridge_list();
     for (cl = options->Bridges; cl; cl = cl->next) {
@@ -1300,11 +1295,6 @@ options_act(const or_options_t *old_options)
     sweep_bridge_list();
   }
 
-  /* If we have pluggable transport related options enabled, see if we
-     should warn the user about potential configuration problems. */
-  if (options->Bridges || options->ClientTransportPlugin)
-    validate_pluggable_transports_config();
-
   if (running_tor && rend_config_services(options, 0)<0) {
     log_warn(LD_BUG,
        "Previously validated hidden services line could not be added!");
@@ -1324,6 +1314,32 @@ options_act(const or_options_t *old_options)
     rep_hist_load_mtbf_data(time(NULL));
   }
 
+  mark_transport_list();
+  pt_prepare_proxy_list_for_config_read();
+  if (options->ClientTransportPlugin) {
+    for (cl = options->ClientTransportPlugin; cl; cl = cl->next) {
+      if (parse_client_transport_line(cl->value, 0)<0) {
+        log_warn(LD_BUG,
+                 "Previously validated ClientTransportPlugin line "
+                 "could not be added!");
+        return -1;
+      }
+    }
+  }
+
+  if (options->ServerTransportPlugin) {
+    for (cl = options->ServerTransportPlugin; cl; cl = cl->next) {
+      if (parse_server_transport_line(cl->value, 0)<0) {
+        log_warn(LD_BUG,
+                 "Previously validated ServerTransportPlugin line "
+                 "could not be added!");
+        return -1;
+      }
+    }
+  }
+  sweep_transport_list();
+  sweep_proxy_list();
+
   /* Bail out at this point if we're not going to be a client or server:
    * we want to not fork, and to log stuff to stderr. */
   if (!running_tor)
@@ -3727,14 +3743,19 @@ options_validate(or_options_t *old_options, or_options_t *options,
   if (options->UseBridges && !options->TunnelDirConns)
     REJECT("If you set UseBridges, you must set TunnelDirConns.");
 
+  for (cl = options->Bridges; cl; cl = cl->next) {
+    if (parse_bridge_line(cl->value, 1)<0)
+      REJECT("Bridge line did not parse. See logs for details.");
+  }
+
   for (cl = options->ClientTransportPlugin; cl; cl = cl->next) {
     if (parse_client_transport_line(cl->value, 1)<0)
       REJECT("Transport line did not parse. See logs for details.");
   }
 
-  for (cl = options->Bridges; cl; cl = cl->next) {
-    if (parse_bridge_line(cl->value, 1)<0)
-      REJECT("Bridge line did not parse. See logs for details.");
+  for (cl = options->ServerTransportPlugin; cl; cl = cl->next) {
+    if (parse_server_transport_line(cl->value, 1)<0)
+      REJECT("Server transport line did not parse. See logs for details.");
   }
 
   if (options->ConstrainedSockets) {
@@ -4702,72 +4723,243 @@ parse_bridge_line(const char *line, int validate_only)
   SMARTLIST_FOREACH(items, char*, s, tor_free(s));
   smartlist_free(items);
   tor_free(addrport);
-  tor_free(fingerprint);
   tor_free(transport_name);
+  tor_free(fingerprint);
   return r;
 }
 
 /** Read the contents of a ClientTransportPlugin line from
  * <b>line</b>. Return 0 if the line is well-formed, and -1 if it
- * isn't. If <b>validate_only</b> is 0, and the line is well-formed,
- * then add the transport described in the line to our internal
- * transport list.
-*/
+ * isn't.
+ *
+ * If <b>validate_only</b> is 0, and the line is well-formed:
+ * - If it's an external proxy line, add the transport described in the line to
+ * our internal transport list.
+ * - If it's a managed proxy line, launch the managed proxy. */
 static int
 parse_client_transport_line(const char *line, int validate_only)
 {
   smartlist_t *items = NULL;
   int r;
-  char *socks_ver_str=NULL;
-  char *name=NULL;
+  char *field2=NULL;
+
+  const char *transports=NULL;
+  smartlist_t *transport_list=NULL;
   char *addrport=NULL;
-  int socks_ver;
   tor_addr_t addr;
   uint16_t port = 0;
+  int socks_ver=PROXY_NONE;
+
+  /* managed proxy options */
+  int is_managed=0;
+  char **proxy_argv=NULL;
+  char **tmp=NULL;
+  int proxy_argc,i;
+
+  int line_length;
 
   items = smartlist_create();
   smartlist_split_string(items, line, NULL,
                          SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, -1);
 
-  if (smartlist_len(items) < 3) {
+  line_length =  smartlist_len(items);
+  if (line_length < 3) {
     log_warn(LD_CONFIG, "Too few arguments on ClientTransportPlugin line.");
     goto err;
   }
 
-  name = smartlist_get(items, 0);
+  /* Get the first line element, split it to commas into
+     transport_list (in case it's multiple transports) and validate
+     the transport names. */
+  transports = smartlist_get(items, 0);
+  transport_list = smartlist_create();
+  smartlist_split_string(transport_list, transports, ",",
+                         SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, 0);
+  SMARTLIST_FOREACH_BEGIN(transport_list, const char *, transport_name) {
+    if (!string_is_C_identifier(transport_name)) {
+      log_warn(LD_CONFIG, "Transport name is not a C identifier (%s).",
+               transport_name);
+      goto err;
+    }
+  } SMARTLIST_FOREACH_END(transport_name);
 
-  socks_ver_str = smartlist_get(items, 1);
+  /* field2 is either a SOCKS version or "exec" */
+  field2 = smartlist_get(items, 1);
 
-  if (!strcmp(socks_ver_str,"socks4"))
+  if (!strcmp(field2,"socks4")) {
     socks_ver = PROXY_SOCKS4;
-  else if (!strcmp(socks_ver_str,"socks5"))
+  } else if (!strcmp(field2,"socks5")) {
     socks_ver = PROXY_SOCKS5;
-  else {
-    log_warn(LD_CONFIG, "Strange ClientTransportPlugin proxy type '%s'.",
-             socks_ver_str);
+  } else if (!strcmp(field2,"exec")) {
+    is_managed=1;
+  } else {
+    log_warn(LD_CONFIG, "Strange ClientTransportPlugin field '%s'.",
+             field2);
     goto err;
   }
 
-  addrport = smartlist_get(items, 2);
+  if (is_managed) { /* managed */
+    if (!validate_only) {  /* if we are not just validating, use the
+                             rest of the line as the argv of the proxy
+                             to be launched */
+      proxy_argc = line_length-2;
+      tor_assert(proxy_argc > 0);
+      proxy_argv = tor_malloc_zero(sizeof(char*)*(proxy_argc+1));
+      tmp = proxy_argv;
+      for (i=0;i<proxy_argc;i++) { /* store arguments */
+        *tmp++ = smartlist_get(items, 2);
+        smartlist_del_keeporder(items, 2);
+      }
+      *tmp = NULL; /*terminated with NUL pointer, just like execve() likes it*/
 
-  if (tor_addr_port_parse(addrport, &addr, &port)<0) {
-    log_warn(LD_CONFIG, "Error parsing transport "
-              "address '%s'", addrport);
+      /* kickstart the thing */
+      pt_kickstart_client_proxy(transport_list, proxy_argv);
+    }
+  } else { /* external */
+    if (smartlist_len(transport_list) != 1) {
+      log_warn(LD_CONFIG, "You can't have an external proxy with "
+               "more than one transports.");
+      goto err;
+    }
+
+    addrport = smartlist_get(items, 2);
+
+    if (tor_addr_port_parse(addrport, &addr, &port)<0) {
+      log_warn(LD_CONFIG, "Error parsing transport "
+               "address '%s'", addrport);
+      goto err;
+    }
+    if (!port) {
+      log_warn(LD_CONFIG,
+               "Transport address '%s' has no port.", addrport);
+      goto err;
+    }
+
+    if (!validate_only) {
+      transport_add_from_config(&addr, port, smartlist_get(transport_list, 0),
+                                socks_ver);
+
+      log_info(LD_DIR, "Transport '%s' found at %s:%d",
+               transports, fmt_addr(&addr), (int)port);
+    }
+  }
+
+  r = 0;
+  goto done;
+
+ err:
+  r = -1;
+
+ done:
+  SMARTLIST_FOREACH(items, char*, s, tor_free(s));
+  smartlist_free(items);
+  SMARTLIST_FOREACH(transport_list, char*, s, tor_free(s));
+  smartlist_free(transport_list);
+
+  return r;
+}
+
+/** Read the contents of a ServerTransportPlugin line from
+ * <b>line</b>. Return 0 if the line is well-formed, and -1 if it
+ * isn't.
+ * If <b>validate_only</b> is 0, the line is well-formed, and it's a
+ * managed proxy line, launch the managed proxy. */
+static int
+parse_server_transport_line(const char *line, int validate_only)
+{
+  smartlist_t *items = NULL;
+  int r;
+  const char *transports=NULL;
+  smartlist_t *transport_list=NULL;
+  char *type=NULL;
+  char *addrport=NULL;
+  tor_addr_t addr;
+  uint16_t port = 0;
+
+  /* managed proxy options */
+  int is_managed=0;
+  char **proxy_argv=NULL;
+  char **tmp=NULL;
+  int proxy_argc,i;
+
+  int line_length;
+
+  items = smartlist_create();
+  smartlist_split_string(items, line, NULL,
+                         SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, -1);
+
+  line_length =  smartlist_len(items);
+  if (line_length < 3) {
+    log_warn(LD_CONFIG, "Too few arguments on ServerTransportPlugin line.");
     goto err;
   }
 
-  if (!port) {
-    log_warn(LD_CONFIG,
-              "Transport address '%s' has no port.", addrport);
+  /* Get the first line element, split it to commas into
+     transport_list (in case it's multiple transports) and validate
+     the transport names. */
+  transports = smartlist_get(items, 0);
+  transport_list = smartlist_create();
+  smartlist_split_string(transport_list, transports, ",",
+                         SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, 0);
+  SMARTLIST_FOREACH_BEGIN(transport_list, const char *, transport_name) {
+    if (!string_is_C_identifier(transport_name)) {
+      log_warn(LD_CONFIG, "Transport name is not a C identifier (%s).",
+               transport_name);
+      goto err;
+    }
+  } SMARTLIST_FOREACH_END(transport_name);
+
+  type = smartlist_get(items, 1);
+
+  if (!strcmp(type, "exec")) {
+    is_managed=1;
+  } else if (!strcmp(type, "proxy")) {
+    is_managed=0;
+  } else {
+    log_warn(LD_CONFIG, "Strange ServerTransportPlugin type '%s'", type);
     goto err;
   }
 
-  if (!validate_only) {
-    log_debug(LD_DIR, "Transport %s found at %s:%d", name,
-              fmt_addr(&addr), (int)port);
+  if (is_managed) { /* managed */
+    if (!validate_only) {
+      proxy_argc = line_length-2;
+      tor_assert(proxy_argc > 0);
+      proxy_argv = tor_malloc_zero(sizeof(char*)*(proxy_argc+1));
+      tmp = proxy_argv;
+
+      for (i=0;i<proxy_argc;i++) { /* store arguments */
+        *tmp++ = smartlist_get(items, 2);
+        smartlist_del_keeporder(items, 2);
+      }
+      *tmp = NULL; /*terminated with NUL pointer, just like execve() likes it*/
+
+      /* kickstart the thing */
+      pt_kickstart_server_proxy(transport_list, proxy_argv);
+    }
+  } else { /* external */
+    if (smartlist_len(transport_list) != 1) {
+      log_warn(LD_CONFIG, "You can't have an external proxy with "
+               "more than one transports.");
+      goto err;
+    }
 
-    if (transport_add_from_config(&addr, port, name, socks_ver) < 0)
+    addrport = smartlist_get(items, 2);
+
+    if (tor_addr_port_parse(addrport, &addr, &port)<0) {
+      log_warn(LD_CONFIG, "Error parsing transport "
+               "address '%s'", addrport);
       goto err;
+    }
+    if (!port) {
+      log_warn(LD_CONFIG,
+               "Transport address '%s' has no port.", addrport);
+      goto err;
+    }
+
+    if (!validate_only) {
+      log_info(LD_DIR, "Server transport '%s' at %s:%d.",
+               transports, fmt_addr(&addr), (int)port);
+    }
   }
 
   r = 0;
@@ -4779,6 +4971,9 @@ parse_client_transport_line(const char *line, int validate_only)
  done:
   SMARTLIST_FOREACH(items, char*, s, tor_free(s));
   smartlist_free(items);
+  SMARTLIST_FOREACH(transport_list, char*, s, tor_free(s));
+  smartlist_free(transport_list);
+
   return r;
 }
 
@@ -5721,6 +5916,69 @@ options_get_datadir_fname2_suffix(const or_options_t *options,
   return fname;
 }
 
+/** Return true if <b>line</b> is a valid state TransportProxy line.
+ *  Return false otherwise. */
+static int
+state_transport_line_is_valid(const char *line)
+{
+  smartlist_t *items = NULL;
+  char *addrport=NULL;
+  tor_addr_t addr;
+  uint16_t port = 0;
+  int r;
+
+  items = smartlist_create();
+  smartlist_split_string(items, line, NULL,
+                         SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, -1);
+
+  if (smartlist_len(items) != 2) {
+    log_warn(LD_CONFIG, "state: Not enough arguments in TransportProxy line.");
+    goto err;
+  }
+
+  addrport = smartlist_get(items, 1);
+  if (tor_addr_port_parse(addrport, &addr, &port) < 0) {
+    log_warn(LD_CONFIG, "state: Could not parse addrport.");
+    goto err;
+  }
+
+  if (!port) {
+    log_warn(LD_CONFIG, "state: Transport line did not contain port.");
+    goto err;
+  }
+
+  r = 1;
+  goto done;
+
+ err:
+  r = 0;
+
+ done:
+  SMARTLIST_FOREACH(items, char*, s, tor_free(s));
+  smartlist_free(items);
+  return r;
+}
+
+/** Return 0 if all TransportProxy lines in <b>state</b> are well
+ *  formed. Otherwise, return -1. */
+static int
+validate_transports_in_state(or_state_t *state)
+{
+  int broken = 0;
+  config_line_t *line;
+
+  for (line = state->TransportProxies ; line ; line = line->next) {
+    tor_assert(!strcmp(line->key, "TransportProxy"));
+    if (!state_transport_line_is_valid(line->value)<0)
+      broken = 1;
+  }
+
+  if (broken)
+    log_warn(LD_CONFIG, "state: State file seems to be broken.");
+
+  return 0;
+}
+
 /** Return 0 if every setting in <b>state</b> is reasonable, and a
  * permissible transition from <b>old_state</b>.  Else warn and return -1.
  * Should have no side effects, except for normalizing the contents of
@@ -5739,6 +5997,9 @@ or_state_validate(or_state_t *old_state, or_state_t *state,
   if (entry_guards_parse_state(state, 0, msg)<0)
     return -1;
 
+  if (validate_transports_in_state(state)<0)
+    return -1;
+
   return 0;
 }
 
@@ -5971,6 +6232,150 @@ or_state_save(time_t now)
   return 0;
 }
 
+/** Return the config line for transport <b>transport</b> in the current state.
+ *  Return NULL if there is no config line for <b>transport</b>. */
+static config_line_t *
+get_transport_in_state_by_name(const char *transport)
+{
+  or_state_t *or_state = get_or_state();
+  config_line_t *line;
+  config_line_t *ret = NULL;
+  smartlist_t *items = NULL;
+
+  for (line = or_state->TransportProxies ; line ; line = line->next) {
+    tor_assert(!strcmp(line->key, "TransportProxy"));
+
+    items = smartlist_create();
+    smartlist_split_string(items, line->value, NULL,
+                           SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, -1);
+    if (smartlist_len(items) != 2) /* broken state */
+      goto done;
+
+    if (!strcmp(smartlist_get(items, 0), transport)) {
+      ret = line;
+      goto done;
+    }
+
+    SMARTLIST_FOREACH(items, char*, s, tor_free(s));
+    smartlist_free(items);
+    items = NULL;
+  }
+
+ done:
+  if (items) {
+    SMARTLIST_FOREACH(items, char*, s, tor_free(s));
+    smartlist_free(items);
+  }
+  return ret;
+}
+
+/** Return string containing the address:port part of the
+ *  TransportProxy <b>line</b> for transport <b>transport</b>.
+ *  If the line is corrupted, return NULL. */
+static const char *
+get_transport_bindaddr(const char *line, const char *transport)
+{
+  char *line_tmp = NULL;
+
+  if (strlen(line) < strlen(transport) + 2) {
+    goto broken_state;
+  } else {
+    /* line should start with the name of the transport and a space.
+       (for example, "obfs2 127.0.0.1:47245") */
+    tor_asprintf(&line_tmp, "%s ", transport);
+    if (strcmpstart(line, line_tmp))
+      goto broken_state;
+
+    tor_free(line_tmp);
+    return (line+strlen(transport)+1);
+  }
+
+ broken_state:
+  tor_free(line_tmp);
+  return NULL;
+}
+
+/** Return a static string containing the address:port a proxy
+ *  transport should bind on. */
+const char *
+get_bindaddr_for_transport(const char *transport)
+{
+  static const char default_addrport[] = "127.0.0.1:0";
+  const char *bindaddr = NULL;
+
+  config_line_t *line = get_transport_in_state_by_name(transport);
+  if (!line)
+    return default_addrport;
+
+  bindaddr = get_transport_bindaddr(line->value, transport);
+
+  return bindaddr ? bindaddr : default_addrport;
+}
+
+/** Save <b>transport</b> listening on <b>addr</b>:<b>port</b> to
+    state */
+void
+save_transport_to_state(const char *transport,
+                        const tor_addr_t *addr, uint16_t port)
+{
+  or_state_t *state = get_or_state();
+
+  char *transport_addrport=NULL;
+
+  /** find where to write on the state */
+  config_line_t **next, *line;
+
+  /* see if this transport is already stored in state */
+  config_line_t *transport_line =
+    get_transport_in_state_by_name(transport);
+
+  if (transport_line) { /* if transport already exists in state... */
+    const char *prev_bindaddr = /* get its addrport... */
+      get_transport_bindaddr(transport_line->value, transport);
+    tor_asprintf(&transport_addrport, "%s:%d", fmt_addr(addr), (int)port);
+
+    /* if transport in state has the same address as this one, life is good */
+    if (!strcmp(prev_bindaddr, transport_addrport)) {
+      log_info(LD_CONFIG, "Transport seems to have spawned on its usual "
+               "address:port.");
+      goto done;
+    } else { /* if addrport in state is different than the one we got */
+      log_info(LD_CONFIG, "Transport seems to have spawned on different "
+               "address:port. Let's update the state file with the new "
+               "address:port");
+      tor_free(transport_line->value); /* free the old line */
+      tor_asprintf(&transport_line->value, "%s %s:%d", transport,
+                   fmt_addr(addr),
+                   (int) port); /* replace old addrport line with new line */
+    }
+  } else { /* never seen this one before; save it in state for next time */
+    log_info(LD_CONFIG, "It's the first time we see this transport. "
+             "Let's save its address:port");
+    next = &state->TransportProxies;
+    /* find the last TransportProxy line in the state and point 'next'
+       right after it  */
+    line = state->TransportProxies;
+    while (line) {
+      next = &(line->next);
+      line = line->next;
+    }
+
+    /* allocate space for the new line and fill it in */
+    *next = line = tor_malloc_zero(sizeof(config_line_t));
+    line->key = tor_strdup("TransportProxy");
+    tor_asprintf(&line->value, "%s %s:%d", transport,
+                 fmt_addr(addr), (int) port);
+
+    next = &(line->next);
+  }
+
+  if (!get_options()->AvoidDiskWrites)
+    or_state_mark_dirty(state, 0);
+
+ done:
+  tor_free(transport_addrport);
+}
+
 /** Given a file name check to see whether the file exists but has not been
  * modified for a very long time.  If so, remove it. */
 void
diff --git a/src/or/config.h b/src/or/config.h
index 4a5afdf178..76f6841d70 100644
--- a/src/or/config.h
+++ b/src/or/config.h
@@ -68,6 +68,11 @@ const smartlist_t *get_configured_client_ports(void);
 
 int options_need_geoip_info(const or_options_t *options,
                             const char **reason_out);
+
+void save_transport_to_state(const char *transport_name,
+                             const tor_addr_t *addr, uint16_t port);
+const char *get_bindaddr_for_transport(const char *transport);
+
 int getinfo_helper_config(control_connection_t *conn,
                           const char *question, char **answer,
                           const char **errmsg);
diff --git a/src/or/connection.c b/src/or/connection.c
index ad63a9d802..45a12715a3 100644
--- a/src/or/connection.c
+++ b/src/or/connection.c
@@ -2020,9 +2020,12 @@ retry_all_listeners(smartlist_t *replaced_conns,
   return retval;
 }
 
-/** Return 1 if we should apply rate limiting to <b>conn</b>,
- * and 0 otherwise. Right now this just checks if it's an internal
- * IP address or an internal connection. */
+/** Return 1 if we should apply rate limiting to <b>conn</b>, and 0
+ * otherwise.
+ * Right now this just checks if it's an internal IP address or an
+ * internal connection. We also check if the connection uses pluggable
+ * transports, since we should then limit it even if it comes from an
+ * internal IP address. */
 static int
 connection_is_rate_limited(connection_t *conn)
 {
diff --git a/src/or/main.c b/src/or/main.c
index 4948d59ec3..aa167e1e9d 100644
--- a/src/or/main.c
+++ b/src/or/main.c
@@ -37,6 +37,7 @@
 #include "ntmain.h"
 #include "onion.h"
 #include "policies.h"
+#include "transports.h"
 #include "relay.h"
 #include "rendclient.h"
 #include "rendcommon.h"
@@ -1086,7 +1087,9 @@ run_scheduled_events(time_t now)
   static int should_init_bridge_stats = 1;
   static time_t time_to_retry_dns_init = 0;
   static time_t time_to_next_heartbeat = 0;
+  static int has_validated_pt = 0;
   const or_options_t *options = get_options();
+
   int is_server = server_mode(options);
   int i;
   int have_dir_info;
@@ -1463,7 +1466,7 @@ run_scheduled_events(time_t now)
     }
   }
 
-  /** 10b. write bridge networkstatus file to disk */
+  /** 10. write bridge networkstatus file to disk */
   if (options->BridgeAuthoritativeDir &&
       time_to_write_bridge_status_file < now) {
     networkstatus_dump_bridge_status_to_file(now);
@@ -1471,6 +1474,7 @@ run_scheduled_events(time_t now)
     time_to_write_bridge_status_file = now+BRIDGE_STATUSFILE_INTERVAL;
   }
 
+  /** 11. check the port forwarding app */
   if (time_to_check_port_forwarding < now &&
       options->PortForwarding &&
       is_server) {
@@ -1482,7 +1486,19 @@ run_scheduled_events(time_t now)
     time_to_check_port_forwarding = now+PORT_FORWARDING_CHECK_INTERVAL;
   }
 
-  /** 11. write the heartbeat message */
+  /** 11b. check pending unconfigured managed proxies */
+  if (pt_proxies_configuration_pending())
+    pt_configure_remaining_proxies();
+
+  /** 11c. validate pluggable transports configuration if we need to */
+  if (!has_validated_pt &&
+      (options->Bridges || options->ClientTransportPlugin)) {
+    if (validate_pluggable_transports_config() == 0) {
+      has_validated_pt = 1;
+    }
+  }
+
+  /** 12. write the heartbeat message */
   if (options->HeartbeatPeriod &&
       time_to_next_heartbeat < now) {
     log_heartbeat(now);
@@ -2341,6 +2357,7 @@ tor_free_all(int postfork)
   clear_pending_onions();
   circuit_free_all();
   entry_guards_free_all();
+  pt_free_all();
   connection_free_all();
   buf_shrink_freelists(1);
   memarea_clear_freelist();
diff --git a/src/or/or.h b/src/or/or.h
index 5c645927e3..d6eaeb6f17 100644
--- a/src/or/or.h
+++ b/src/or/or.h
@@ -2879,6 +2879,9 @@ typedef struct {
   config_line_t *ClientTransportPlugin; /**< List of client
                                            transport plugins. */
 
+  config_line_t *ServerTransportPlugin; /**< List of client
+                                           transport plugins. */
+
   int BridgeRelay; /**< Boolean: are we acting as a bridge relay? We make
                     * this explicit so we can change how we behave in the
                     * future. */
@@ -3350,6 +3353,8 @@ typedef struct {
   /** A list of Entry Guard-related configuration lines. */
   config_line_t *EntryGuards;
 
+  config_line_t *TransportProxies;
+
   /** These fields hold information on the history of bandwidth usage for
    * servers.  The "Ends" fields hold the time when we last updated the
    * bandwidth usage. The "Interval" fields hold the granularity, in seconds,
diff --git a/src/or/transports.c b/src/or/transports.c
new file mode 100644
index 0000000000..3c533ccd95
--- /dev/null
+++ b/src/or/transports.c
@@ -0,0 +1,1048 @@
+/* Copyright (c) 2011, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+
+/**
+ * \file transports.c
+ * \brief Pluggable Transports related code.
+ **/
+
+#define PT_PRIVATE
+#include "or.h"
+#include "config.h"
+#include "circuitbuild.h"
+#include "transports.h"
+#include "util.h"
+
+static void set_managed_proxy_environment(char ***envp,
+                                          const managed_proxy_t *mp);
+static INLINE int proxy_configuration_finished(const managed_proxy_t *mp);
+
+static void managed_proxy_destroy(managed_proxy_t *mp);
+
+static void handle_finished_proxy(managed_proxy_t *mp);
+static void configure_proxy(managed_proxy_t *mp);
+
+static void parse_method_error(const char *line, int is_server_method);
+#define parse_server_method_error(l) parse_method_error(l, 1)
+#define parse_client_method_error(l) parse_method_error(l, 0)
+
+static INLINE void free_execve_args(char **arg);
+
+/** Managed proxy protocol strings */
+#define PROTO_ENV_ERROR "ENV-ERROR"
+#define PROTO_NEG_SUCCESS "VERSION"
+#define PROTO_NEG_FAIL "VERSION-ERROR no-version"
+#define PROTO_CMETHOD "CMETHOD"
+#define PROTO_SMETHOD "SMETHOD"
+#define PROTO_CMETHOD_ERROR "CMETHOD-ERROR"
+#define PROTO_SMETHOD_ERROR "SMETHOD-ERROR"
+#define PROTO_CMETHODS_DONE "CMETHODS DONE"
+#define PROTO_SMETHODS_DONE "SMETHODS DONE"
+
+/* The smallest valid managed proxy protocol line that can
+   appear. It's the size of "VERSION 1" */
+#define SMALLEST_MANAGED_LINE_SIZE 9
+
+/** Number of environment variables for managed proxy clients/servers. */
+#define ENVIRON_SIZE_CLIENT 5
+#define ENVIRON_SIZE_SERVER 8
+
+/** The first and only supported - at the moment - configuration
+    protocol version. */
+#define PROTO_VERSION_ONE 1
+
+/** List of unconfigured managed proxies. */
+static smartlist_t *managed_proxy_list = NULL;
+/** Number of still unconfigured proxies. */
+static int unconfigured_proxies_n = 0;
+
+/** "The main idea is:"
+
+    Each managed proxy is represented by a 'managed_proxy_t'.
+    Each managed proxy can support multiple transports.
+    Each managed proxy gets configured through a multistep process.
+
+    'managed_proxy_list' contains all the managed proxies this tor
+    instance is supporting.
+    In the 'managed_proxy_list' there are 'unconfigured_proxies_n'
+    managed proxies that are still unconfigured.
+
+    In every run_scheduled_event() tick, we attempt to launch and then
+    configure the unconfiged managed proxies, using the configuration
+    protocol defined in the 180_pluggable_transport.txt proposal. A
+    managed proxy might need several ticks to get fully configured.
+
+    When a managed proxy is fully configured, we register all its
+    transports to the circuitbuild.c subsystem. At that point the
+    transports are owned by the circuitbuild.c subsystem.
+
+    When a managed proxy fails to follow the 180 configuration
+    protocol, it gets marked as broken and gets destroyed.
+
+    "In a little more technical detail:"
+
+    While we are serially parsing torrc, we store all the transports
+    that a proxy should spawn in its 'transports_to_launch' element.
+
+    When we finish reading the torrc, we spawn the managed proxy and
+    expect {S,C}METHOD lines from its output. We add transports
+    described by METHOD lines to its 'transports' element, as
+    'transport_t' structs.
+
+    When the managed proxy stops spitting METHOD lines (signified by a
+    '{S,C}METHODS DONE' message) we register all the transports
+    collected to the circuitbuild.c subsystem. At this point, the
+    'transport_t's can be transformed into dangling pointers at any
+    point by the circuitbuild.c subsystem, and so we replace all
+    'transport_t's with strings describing the transport names.  We
+    can still go from a transport name to a 'transport_t' using the
+    fact that transport names uniquely identify 'transport_t's.
+
+    "In even more technical detail I shall describe what happens when
+    the SIGHUP bell tolls:"
+
+    We immediately destroy all unconfigured proxies (We shouldn't have
+    unconfigured proxies in the first place, except when SIGHUP rings
+    immediately after tor is launched.).
+
+    We mark all managed proxies and transports to signify that they
+    must be removed if they don't contribute by the new torrc
+    (marked_for_removal).
+    We also mark all managed proxies to signify that they might need
+    to be restarted so that they end up supporting all the transports
+    the new torrc wants them to support (got_hup).
+    We also clear their 'transports_to_launch' list so that we can put
+    there the transports we need to launch according to the new torrc.
+
+    We then start parsing torrc again.
+
+    Everytime we encounter a transport line using a known pre-SIGHUP
+    managed proxy, we cleanse that proxy from the removal mark.
+
+    We also mark it as unconfigured so that on the next scheduled
+    events tick, we investigate whether we need to restart the proxy
+    so that it also spawns the new transports.
+    If the post-SIGHUP 'transports_to_launch' list is identical to the
+    pre-SIGHUP one, it means that no changes were introduced to this
+    proxy during the SIGHUP and no restart has to take place.
+
+    During the post-SIGHUP torrc parsing, we unmark all transports
+    spawned by managed proxies that we find in our torrc.
+    We do that so that if we don't need to restart a managed proxy, we
+    can continue using its old transports normally.
+    If we end up restarting the proxy, we destroy and unregister all
+    old transports from the circuitbuild.c subsystem.
+*/
+
+/** Return true if there are still unconfigured managed proxies. */
+int
+pt_proxies_configuration_pending(void)
+{
+  return !! unconfigured_proxies_n;
+}
+
+/** Return true if <b>mp</b> has the same argv as <b>proxy_argv</b> */
+static int
+managed_proxy_has_argv(const managed_proxy_t *mp, char **proxy_argv)
+{
+  char **tmp1=proxy_argv;
+  char **tmp2=mp->argv;
+
+  tor_assert(tmp1);
+  tor_assert(tmp2);
+
+  while (*tmp1 && *tmp2) {
+    if (strcmp(*tmp1++, *tmp2++))
+      return 0;
+  }
+
+  if (!*tmp1 && !*tmp2)
+    return 1;
+
+  return 0;
+}
+
+/** Return a managed proxy with the same argv as <b>proxy_argv</b>.
+ *  If no such managed proxy exists, return NULL. */
+static managed_proxy_t *
+get_managed_proxy_by_argv_and_type(char **proxy_argv, int is_server)
+{
+  if (!managed_proxy_list)
+    return NULL;
+
+  SMARTLIST_FOREACH_BEGIN(managed_proxy_list,  managed_proxy_t *, mp) {
+    if (managed_proxy_has_argv(mp, proxy_argv) &&
+        mp->is_server == is_server)
+      return mp;
+  } SMARTLIST_FOREACH_END(mp);
+
+  return NULL;
+}
+
+/** Add <b>transport</b> to managed proxy <b>mp</b>. */
+static void
+add_transport_to_proxy(const char *transport, managed_proxy_t *mp)
+{
+  tor_assert(mp->transports_to_launch);
+  if (!smartlist_string_isin(mp->transports_to_launch, transport))
+    smartlist_add(mp->transports_to_launch, tor_strdup(transport));
+}
+
+/** Called when a SIGHUP occurs. Returns true if managed proxy
+ *  <b>mp</b> needs to be restarted after the SIGHUP, based on the new
+ *  torrc. */
+static int
+proxy_needs_restart(const managed_proxy_t *mp)
+{
+  /* mp->transport_to_launch is populated with the names of the
+     transports that must be launched *after* the SIGHUP.
+     mp->transports is populated with the names of the transports that
+     were launched *before* the SIGHUP.
+
+     If the two lists contain the same strings, we don't need to
+     restart the proxy, since it already does what we want. */
+
+  tor_assert(smartlist_len(mp->transports_to_launch) > 0);
+  tor_assert(mp->conf_state == PT_PROTO_COMPLETED);
+
+  if (smartlist_len(mp->transports_to_launch) != smartlist_len(mp->transports))
+    goto needs_restart;
+
+  SMARTLIST_FOREACH_BEGIN(mp->transports_to_launch, char *, t_t_l) {
+    if (!smartlist_string_isin(mp->transports, t_t_l))
+      goto needs_restart;
+
+  } SMARTLIST_FOREACH_END(t_t_l);
+
+  return 0;
+
+ needs_restart:
+  return 1;
+}
+
+/** Managed proxy <b>mp</b> must be restarted. Do all the necessary
+ *  preparations and then flag its state so that it will be relaunched
+ *  in the next tick. */
+static void
+proxy_prepare_for_restart(managed_proxy_t *mp)
+{
+  transport_t *t_tmp = NULL;
+
+  tor_assert(mp->conf_state == PT_PROTO_COMPLETED);
+  tor_assert(mp->pid);
+
+  /* kill the old obfsproxy process */
+  tor_terminate_process(mp->pid);
+  mp->pid = 0;
+  fclose(mp->_stdout);
+
+  /* destroy all its old transports. we no longer use them. */
+  SMARTLIST_FOREACH_BEGIN(mp->transports, const char *, t_name) {
+    t_tmp = transport_get_by_name(t_name);
+    if (t_tmp)
+      t_tmp->marked_for_removal = 1;
+  } SMARTLIST_FOREACH_END(t_name);
+  sweep_transport_list();
+
+  /* free the transport names in mp->transports */
+  SMARTLIST_FOREACH(mp->transports, char *, t_name, tor_free(t_name));
+  smartlist_clear(mp->transports);
+
+  /* flag it as an infant proxy so that it gets launched on next tick */
+  mp->conf_state = PT_PROTO_INFANT;
+}
+
+/** Launch managed proxy <b>mp</b>. */
+static int
+launch_managed_proxy(managed_proxy_t *mp)
+{
+  (void) mp;
+  (void) set_managed_proxy_environment;
+  return -1;
+#if 0
+  /* XXXX023 we must reenable this code for managed proxies to work.
+   *   "All it needs" is revision to work with the new tor_spawn_background
+   *   API. */
+  char **envp=NULL;
+  int pid;
+  process_handle_t proc;
+  FILE *stdout_read = NULL;
+  int stdout_pipe=-1, stderr_pipe=-1;
+
+  /* prepare the environment variables for the managed proxy */
+  set_managed_proxy_environment(&envp, mp);
+
+  pid = tor_spawn_background(mp->argv[0], (const char **)mp->argv,
+                             (const char **)envp, &proc);
+  if (pid < 0) {
+    log_warn(LD_GENERAL, "Managed proxy at '%s' failed at launch.",
+             mp->argv[0]);
+    return -1;
+  }
+
+  /* free the memory allocated by set_managed_proxy_environment(). */
+  free_execve_args(envp);
+
+  /* Set stdout/stderr pipes to be non-blocking */
+#ifdef _WIN32
+  {
+    u_long nonblocking = 1;
+    ioctlsocket(stdout_pipe, FIONBIO, &nonblocking);
+  }
+#else
+    fcntl(stdout_pipe, F_SETFL, O_NONBLOCK);
+#endif
+
+  /* Open the buffered IO streams */
+  stdout_read = fdopen(stdout_pipe, "r");
+
+  log_info(LD_CONFIG, "Managed proxy has spawned at PID %d.", pid);
+
+  mp->conf_state = PT_PROTO_LAUNCHED;
+  mp->_stdout = stdout_read;
+  mp->pid = pid;
+#endif
+  return 0;
+}
+
+/** Check if any of the managed proxies we are currently trying to
+ *  configure have anything new to say. This is called from
+ *  run_scheduled_events(). */
+void
+pt_configure_remaining_proxies(void)
+{
+  log_debug(LD_CONFIG, "Configuring remaining managed proxies (%d)!",
+            unconfigured_proxies_n);
+  SMARTLIST_FOREACH_BEGIN(managed_proxy_list,  managed_proxy_t *, mp) {
+    tor_assert(mp->conf_state != PT_PROTO_BROKEN);
+
+    if (mp->got_hup) {
+      mp->got_hup = 0;
+
+    /* This proxy is marked by a SIGHUP. Check whether we need to
+       restart it. */
+      if (proxy_needs_restart(mp)) {
+        log_info(LD_GENERAL, "Preparing managed proxy for restart.");
+        proxy_prepare_for_restart(mp);
+        continue;
+      } else { /* it doesn't need to be restarted. */
+        log_info(LD_GENERAL, "Nothing changed for managed proxy after HUP: "
+                 "not restarting.");
+        unconfigured_proxies_n--;
+        tor_assert(unconfigured_proxies_n >= 0);
+      }
+
+      continue;
+    }
+
+    /* If the proxy is not fully configured, try to configure it
+       futher. */
+    if (!proxy_configuration_finished(mp))
+      configure_proxy(mp);
+
+  } SMARTLIST_FOREACH_END(mp);
+}
+
+/** Attempt to continue configuring managed proxy <b>mp</b>. */
+static void
+configure_proxy(managed_proxy_t *mp)
+{
+  enum stream_status r;
+  char stdout_buf[200];
+
+  /* if we haven't launched the proxy yet, do it now */
+  if (mp->conf_state == PT_PROTO_INFANT) {
+    launch_managed_proxy(mp);
+    return;
+  }
+
+  tor_assert(mp->conf_state != PT_PROTO_INFANT);
+
+  while (1) {
+    r = get_string_from_pipe(mp->_stdout, stdout_buf,
+                             sizeof(stdout_buf) - 1);
+
+    if (r  == IO_STREAM_OKAY) { /* got a line; handle it! */
+      handle_proxy_line((const char *)stdout_buf, mp);
+    } else if (r == IO_STREAM_EAGAIN) { /* check back later */
+      return;
+    } else if (r == IO_STREAM_CLOSED || r == IO_STREAM_TERM) { /* snap! */
+      log_notice(LD_GENERAL, "Managed proxy stream closed. "
+                 "Most probably application stopped running");
+      mp->conf_state = PT_PROTO_BROKEN;
+    } else { /* unknown stream status */
+      log_notice(LD_GENERAL, "Unknown stream status while configuring proxy.");
+    }
+
+    /* if the proxy finished configuring, exit the loop. */
+    if (proxy_configuration_finished(mp)) {
+      handle_finished_proxy(mp);
+      return;
+    }
+  }
+}
+
+/** Register server managed proxy <b>mp</b> transports to state */
+static void
+register_server_proxy(managed_proxy_t *mp)
+{
+  /* After we register this proxy's transports, we switch its
+     mp->transports to a list containing strings of its transport
+     names. (See transports.h) */
+  smartlist_t *sm_tmp = smartlist_create();
+
+  tor_assert(mp->conf_state != PT_PROTO_COMPLETED);
+  SMARTLIST_FOREACH_BEGIN(mp->transports, transport_t *, t) {
+    save_transport_to_state(t->name, &t->addr, t->port);
+    smartlist_add(sm_tmp, tor_strdup(t->name));
+  } SMARTLIST_FOREACH_END(t);
+
+  /* Since server proxies don't register their transports in the
+     circuitbuild.c subsystem, it's our duty to free them when we
+     switch mp->transports to strings. */
+  SMARTLIST_FOREACH(mp->transports, transport_t *, t, transport_free(t));
+  smartlist_free(mp->transports);
+
+  mp->transports = sm_tmp;
+}
+
+/** Register all the transports supported by client managed proxy
+ *  <b>mp</b> to the bridge subsystem. */
+static void
+register_client_proxy(managed_proxy_t *mp)
+{
+  int r;
+  /* After we register this proxy's transports, we switch its
+     mp->transports to a list containing strings of its transport
+     names. (See transports.h) */
+  smartlist_t *sm_tmp = smartlist_create();
+
+  tor_assert(mp->conf_state != PT_PROTO_COMPLETED);
+  SMARTLIST_FOREACH_BEGIN(mp->transports, transport_t *, t) {
+    r = transport_add(t);
+    switch (r) {
+    case -1:
+      log_notice(LD_GENERAL, "Could not add transport %s. Skipping.", t->name);
+      transport_free(t);
+      break;
+    case 0:
+      log_info(LD_GENERAL, "Succesfully registered transport %s", t->name);
+      smartlist_add(sm_tmp, tor_strdup(t->name));
+      break;
+    case 1:
+      log_info(LD_GENERAL, "Succesfully registered transport %s", t->name);
+      smartlist_add(sm_tmp, tor_strdup(t->name));
+      transport_free(t);
+      break;
+    }
+  } SMARTLIST_FOREACH_END(t);
+
+  smartlist_free(mp->transports);
+  mp->transports = sm_tmp;
+}
+
+/** Register the transports of managed proxy <b>mp</b>. */
+static INLINE void
+register_proxy(managed_proxy_t *mp)
+{
+  if (mp->is_server)
+    register_server_proxy(mp);
+  else
+    register_client_proxy(mp);
+}
+
+/** Free memory allocated by managed proxy <b>mp</b>. */
+static void
+managed_proxy_destroy(managed_proxy_t *mp)
+{
+  if (mp->conf_state != PT_PROTO_COMPLETED)
+    SMARTLIST_FOREACH(mp->transports, transport_t *, t, transport_free(t));
+  else
+    SMARTLIST_FOREACH(mp->transports, char *, t_name, tor_free(t_name));
+
+  /* free the transports smartlist */
+  smartlist_free(mp->transports);
+
+  /* free the transports_to_launch smartlist */
+  SMARTLIST_FOREACH(mp->transports_to_launch, char *, t, tor_free(t));
+  smartlist_free(mp->transports_to_launch);
+
+  /* remove it from the list of managed proxies */
+  smartlist_remove(managed_proxy_list, mp);
+
+  /* close its stdout stream */
+  if (mp->_stdout)
+    fclose(mp->_stdout);
+
+  /* free the argv */
+  free_execve_args(mp->argv);
+
+  if (mp->pid)
+    tor_terminate_process(mp->pid);
+
+  tor_free(mp);
+}
+
+/** Handle a configured or broken managed proxy <b>mp</b>. */
+static void
+handle_finished_proxy(managed_proxy_t *mp)
+{
+  switch (mp->conf_state) {
+  case PT_PROTO_BROKEN: /* if broken: */
+    managed_proxy_destroy(mp); /* annihilate it. */
+    break;
+  case PT_PROTO_CONFIGURED: /* if configured correctly: */
+    register_proxy(mp); /* register its transports */
+    mp->conf_state = PT_PROTO_COMPLETED; /* and mark it as completed. */
+    break;
+  case PT_PROTO_INFANT:
+  case PT_PROTO_LAUNCHED:
+  case PT_PROTO_ACCEPTING_METHODS:
+  case PT_PROTO_COMPLETED:
+  default:
+    log_warn(LD_CONFIG, "Unexpected managed proxy state in "
+             "handle_finished_proxy().");
+    tor_assert(0);
+  }
+
+  unconfigured_proxies_n--;
+  tor_assert(unconfigured_proxies_n >= 0);
+}
+
+/** Return true if the configuration of the managed proxy <b>mp</b> is
+    finished. */
+static INLINE int
+proxy_configuration_finished(const managed_proxy_t *mp)
+{
+  return (mp->conf_state == PT_PROTO_CONFIGURED ||
+          mp->conf_state == PT_PROTO_BROKEN);
+}
+
+/** This function is called when a proxy sends an {S,C}METHODS DONE message. */
+static void
+handle_methods_done(const managed_proxy_t *mp)
+{
+  tor_assert(mp->transports);
+
+  if (smartlist_len(mp->transports) == 0)
+    log_notice(LD_GENERAL, "Proxy was spawned successfully, "
+               "but it didn't laucn any pluggable transport listeners!");
+
+  log_info(LD_CONFIG, "%s managed proxy configuration completed!",
+           mp->is_server ? "Server" : "Client");
+}
+
+/** Handle a configuration protocol <b>line</b> received from a
+ *  managed proxy <b>mp</b>. */
+void
+handle_proxy_line(const char *line, managed_proxy_t *mp)
+{
+  log_debug(LD_GENERAL, "Got a line from managed proxy: %s\n", line);
+
+  if (strlen(line) < SMALLEST_MANAGED_LINE_SIZE) {
+    log_warn(LD_GENERAL, "Managed proxy configuration line is too small. "
+             "Discarding");
+    goto err;
+  }
+
+  if (!strcmpstart(line, PROTO_ENV_ERROR)) {
+    if (mp->conf_state != PT_PROTO_LAUNCHED)
+      goto err;
+
+    parse_env_error(line);
+    goto err;
+  } else if (!strcmpstart(line, PROTO_NEG_FAIL)) {
+    if (mp->conf_state != PT_PROTO_LAUNCHED)
+      goto err;
+
+    log_warn(LD_CONFIG, "Managed proxy could not pick a "
+             "configuration protocol version.");
+    goto err;
+  } else if (!strcmpstart(line, PROTO_NEG_SUCCESS)) {
+    if (mp->conf_state != PT_PROTO_LAUNCHED)
+      goto err;
+
+    if (parse_version(line,mp) < 0)
+      goto err;
+
+    tor_assert(mp->conf_protocol != 0);
+    mp->conf_state = PT_PROTO_ACCEPTING_METHODS;
+    return;
+  } else if (!strcmpstart(line, PROTO_CMETHODS_DONE)) {
+    if (mp->conf_state != PT_PROTO_ACCEPTING_METHODS)
+      goto err;
+
+    handle_methods_done(mp);
+
+    mp->conf_state = PT_PROTO_CONFIGURED;
+    return;
+  } else if (!strcmpstart(line, PROTO_SMETHODS_DONE)) {
+    if (mp->conf_state != PT_PROTO_ACCEPTING_METHODS)
+      goto err;
+
+    handle_methods_done(mp);
+
+    mp->conf_state = PT_PROTO_CONFIGURED;
+    return;
+  } else if (!strcmpstart(line, PROTO_CMETHOD_ERROR)) {
+    if (mp->conf_state != PT_PROTO_ACCEPTING_METHODS)
+      goto err;
+
+    parse_client_method_error(line);
+    goto err;
+  } else if (!strcmpstart(line, PROTO_SMETHOD_ERROR)) {
+    if (mp->conf_state != PT_PROTO_ACCEPTING_METHODS)
+      goto err;
+
+    parse_server_method_error(line);
+    goto err;
+  } else if (!strcmpstart(line, PROTO_CMETHOD)) {
+    if (mp->conf_state != PT_PROTO_ACCEPTING_METHODS)
+      goto err;
+
+    if (parse_cmethod_line(line, mp) < 0)
+      goto err;
+
+    return;
+  } else if (!strcmpstart(line, PROTO_SMETHOD)) {
+    if (mp->conf_state != PT_PROTO_ACCEPTING_METHODS)
+      goto err;
+
+    if (parse_smethod_line(line, mp) < 0)
+      goto err;
+
+    return;
+  } else if (!strcmpstart(line, SPAWN_ERROR_MESSAGE)) {
+    log_warn(LD_GENERAL, "Could not launch managed proxy executable!");
+    goto err;
+  }
+
+  log_warn(LD_CONFIG, "Unknown line received by managed proxy. (%s)", line);
+
+ err:
+  mp->conf_state = PT_PROTO_BROKEN;
+  return;
+}
+
+/** Parses an ENV-ERROR <b>line</b> and warns the user accordingly. */
+void
+parse_env_error(const char *line)
+{
+  /* (Length of the protocol string) plus (a space) and (the first char of
+     the error message) */
+  if (strlen(line) < (strlen(PROTO_ENV_ERROR) + 2))
+    log_notice(LD_CONFIG, "Managed proxy sent us an %s without an error "
+               "message.", PROTO_ENV_ERROR);
+
+  log_warn(LD_CONFIG, "Managed proxy couldn't understand the "
+           "pluggable transport environment variables. (%s)",
+           line+strlen(PROTO_ENV_ERROR)+1);
+}
+
+/** Handles a VERSION <b>line</b>. Updates the configuration protocol
+ *  version in <b>mp</b>. */
+int
+parse_version(const char *line, managed_proxy_t *mp)
+{
+  if (strlen(line) < (strlen(PROTO_NEG_SUCCESS) + 2)) {
+    log_warn(LD_CONFIG, "Managed proxy sent us malformed %s line.",
+             PROTO_NEG_SUCCESS);
+    return -1;
+  }
+
+  if (strcmp("1", line+strlen(PROTO_NEG_SUCCESS)+1)) { /* hardcoded temp */
+    log_warn(LD_CONFIG, "Managed proxy tried to negotiate on version '%s'. "
+             "We only support version '1'", line+strlen(PROTO_NEG_SUCCESS)+1);
+    return -1;
+  }
+
+  mp->conf_protocol = PROTO_VERSION_ONE; /* temp. till more versions appear */
+  return 0;
+}
+
+/** Parses {C,S}METHOD-ERROR <b>line</b> and warns the user
+ *  accordingly.  If <b>is_server</b> it is an SMETHOD-ERROR,
+ *  otherwise it is a CMETHOD-ERROR. */
+static void
+parse_method_error(const char *line, int is_server)
+{
+  const char* error = is_server ?
+    PROTO_SMETHOD_ERROR : PROTO_CMETHOD_ERROR;
+
+  /* (Length of the protocol string) plus (a space) and (the first char of
+     the error message) */
+  if (strlen(line) < (strlen(error) + 2))
+    log_warn(LD_CONFIG, "Managed proxy sent us an %s without an error "
+             "message.", error);
+
+  log_warn(LD_CONFIG, "%s managed proxy encountered a method error. (%s)",
+           is_server ? "Server" : "Client",
+           line+strlen(error)+1);
+}
+
+/** Parses an SMETHOD <b>line</b> and if well-formed it registers the
+ *  new transport in <b>mp</b>. */
+int
+parse_smethod_line(const char *line, managed_proxy_t *mp)
+{
+  int r;
+  smartlist_t *items = NULL;
+
+  char *method_name=NULL;
+
+  char *addrport=NULL;
+  tor_addr_t addr;
+  uint16_t port = 0;
+
+  transport_t *transport=NULL;
+
+  items = smartlist_create();
+  smartlist_split_string(items, line, NULL,
+                         SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, -1);
+  if (smartlist_len(items) < 3) {
+    log_warn(LD_CONFIG, "Server managed proxy sent us a SMETHOD line "
+             "with too few arguments.");
+    goto err;
+  }
+
+  tor_assert(!strcmp(smartlist_get(items,0),PROTO_SMETHOD));
+
+  method_name = smartlist_get(items,1);
+  if (!string_is_C_identifier(method_name)) {
+    log_warn(LD_CONFIG, "Transport name is not a C identifier (%s).",
+             method_name);
+    goto err;
+  }
+
+  addrport = smartlist_get(items, 2);
+  if (tor_addr_port_parse(addrport, &addr, &port)<0) {
+    log_warn(LD_CONFIG, "Error parsing transport "
+             "address '%s'", addrport);
+    goto err;
+  }
+
+  if (!port) {
+    log_warn(LD_CONFIG,
+             "Transport address '%s' has no port.", addrport);
+    goto err;
+  }
+
+  transport = transport_create(&addr, port, method_name, PROXY_NONE);
+  if (!transport)
+    goto err;
+
+  smartlist_add(mp->transports, transport);
+
+  /* For now, notify the user so that he knows where the server
+     transport is listening. */
+  log_info(LD_CONFIG, "Server transport %s at %s:%d.",
+           method_name, fmt_addr(&addr), (int)port);
+
+  r=0;
+  goto done;
+
+ err:
+  r = -1;
+
+ done:
+  SMARTLIST_FOREACH(items, char*, s, tor_free(s));
+  smartlist_free(items);
+  return r;
+}
+
+/** Parses a CMETHOD <b>line</b>, and if well-formed it registers
+ *  the new transport in <b>mp</b>. */
+int
+parse_cmethod_line(const char *line, managed_proxy_t *mp)
+{
+  int r;
+  smartlist_t *items = NULL;
+
+  char *method_name=NULL;
+
+  char *socks_ver_str=NULL;
+  int socks_ver=PROXY_NONE;
+
+  char *addrport=NULL;
+  tor_addr_t addr;
+  uint16_t port = 0;
+
+  transport_t *transport=NULL;
+
+  items = smartlist_create();
+  smartlist_split_string(items, line, NULL,
+                         SPLIT_SKIP_SPACE|SPLIT_IGNORE_BLANK, -1);
+  if (smartlist_len(items) < 4) {
+    log_warn(LD_CONFIG, "Client managed proxy sent us a CMETHOD line "
+             "with too few arguments.");
+    goto err;
+  }
+
+  tor_assert(!strcmp(smartlist_get(items,0),PROTO_CMETHOD));
+
+  method_name = smartlist_get(items,1);
+  if (!string_is_C_identifier(method_name)) {
+    log_warn(LD_CONFIG, "Transport name is not a C identifier (%s).",
+             method_name);
+    goto err;
+  }
+
+  socks_ver_str = smartlist_get(items,2);
+
+  if (!strcmp(socks_ver_str,"socks4")) {
+    socks_ver = PROXY_SOCKS4;
+  } else if (!strcmp(socks_ver_str,"socks5")) {
+    socks_ver = PROXY_SOCKS5;
+  } else {
+    log_warn(LD_CONFIG, "Client managed proxy sent us a proxy protocol "
+             "we don't recognize. (%s)", socks_ver_str);
+    goto err;
+  }
+
+  addrport = smartlist_get(items, 3);
+  if (tor_addr_port_parse(addrport, &addr, &port)<0) {
+    log_warn(LD_CONFIG, "Error parsing transport "
+             "address '%s'", addrport);
+    goto err;
+  }
+
+  if (!port) {
+    log_warn(LD_CONFIG,
+             "Transport address '%s' has no port.", addrport);
+    goto err;
+  }
+
+  transport = transport_create(&addr, port, method_name, socks_ver);
+  if (!transport)
+    goto err;
+
+  smartlist_add(mp->transports, transport);
+
+  log_info(LD_CONFIG, "Transport %s at %s:%d with SOCKS %d. "
+           "Attached to managed proxy.",
+           method_name, fmt_addr(&addr), (int)port, socks_ver);
+
+  r=0;
+  goto done;
+
+ err:
+  r = -1;
+
+ done:
+  SMARTLIST_FOREACH(items, char*, s, tor_free(s));
+  smartlist_free(items);
+  return r;
+}
+
+/** Return a string containing the address:port that <b>transport</b>
+ *  should use. It's the responsibility of the caller to free() the
+ *  received string. */
+static char *
+get_bindaddr_for_proxy(const managed_proxy_t *mp)
+{
+  char *bindaddr = NULL;
+  smartlist_t *string_tmp = smartlist_create();
+
+  tor_assert(mp->is_server);
+
+  SMARTLIST_FOREACH_BEGIN(mp->transports_to_launch, char *, t) {
+    tor_asprintf(&bindaddr, "%s-%s", t, get_bindaddr_for_transport(t));
+    smartlist_add(string_tmp, bindaddr);
+  } SMARTLIST_FOREACH_END(t);
+
+  bindaddr = smartlist_join_strings(string_tmp, ",", 0, NULL);
+
+  SMARTLIST_FOREACH(string_tmp, char *, t, tor_free(t));
+  smartlist_free(string_tmp);
+
+  return bindaddr;
+}
+
+/** Prepare the <b>envp</b> of managed proxy <b>mp</b> */
+static void
+set_managed_proxy_environment(char ***envp, const managed_proxy_t *mp)
+{
+  const or_options_t *options = get_options();
+  char **tmp=NULL;
+  char *state_loc=NULL;
+  char *transports_to_launch=NULL;
+  char *bindaddr=NULL;
+
+  int n_envs = mp->is_server ? ENVIRON_SIZE_SERVER : ENVIRON_SIZE_CLIENT;
+
+  /* allocate enough space for our env. vars and a NULL pointer */
+  *envp = tor_malloc(sizeof(char*)*(n_envs+1));
+  tmp = *envp;
+
+  state_loc = get_datadir_fname("pt_state/"); /* XXX temp */
+  transports_to_launch =
+    smartlist_join_strings(mp->transports_to_launch, ",", 0, NULL);
+
+  tor_asprintf(tmp++, "HOME=%s", getenv("HOME"));
+  tor_asprintf(tmp++, "PATH=%s", getenv("PATH"));
+  tor_asprintf(tmp++, "TOR_PT_STATE_LOCATION=%s", state_loc);
+  tor_asprintf(tmp++, "TOR_PT_MANAGED_TRANSPORT_VER=1"); /* temp */
+  if (mp->is_server) {
+    bindaddr = get_bindaddr_for_proxy(mp);
+
+    /* XXX temp */
+    tor_asprintf(tmp++, "TOR_PT_ORPORT=127.0.0.1:%d", options->ORPort);
+    tor_asprintf(tmp++, "TOR_PT_SERVER_BINDADDR=%s", bindaddr);
+    tor_asprintf(tmp++, "TOR_PT_SERVER_TRANSPORTS=%s", transports_to_launch);
+    /* XXX temp*/
+    tor_asprintf(tmp++, "TOR_PT_EXTENDED_SERVER_PORT=127.0.0.1:4200");
+  } else {
+    tor_asprintf(tmp++, "TOR_PT_CLIENT_TRANSPORTS=%s", transports_to_launch);
+  }
+  *tmp = NULL;
+
+  tor_free(state_loc);
+  tor_free(transports_to_launch);
+  tor_free(bindaddr);
+}
+
+/** Create and return a new managed proxy for <b>transport</b> using
+ *  <b>proxy_argv</b>. If <b>is_server</b> is true, it's a server
+ *  managed proxy. */
+static managed_proxy_t *
+managed_proxy_create(const smartlist_t *transport_list,
+                     char **proxy_argv, int is_server)
+{
+  managed_proxy_t *mp = tor_malloc_zero(sizeof(managed_proxy_t));
+  mp->conf_state = PT_PROTO_INFANT;
+  mp->is_server = is_server;
+  mp->argv = proxy_argv;
+  mp->transports = smartlist_create();
+
+  mp->transports_to_launch = smartlist_create();
+  SMARTLIST_FOREACH(transport_list, const char *, transport,
+                    add_transport_to_proxy(transport, mp));
+
+  /* register the managed proxy */
+  if (!managed_proxy_list)
+    managed_proxy_list = smartlist_create();
+  smartlist_add(managed_proxy_list, mp);
+  unconfigured_proxies_n++;
+
+  return mp;
+}
+
+/** Register <b>transport</b> using proxy with <b>proxy_argv</b> to
+ *  the managed proxy subsystem.
+ *  If <b>is_server</b> is true, then the proxy is a server proxy. */
+void
+pt_kickstart_proxy(const smartlist_t *transport_list,
+                   char **proxy_argv, int is_server)
+{
+  managed_proxy_t *mp=NULL;
+  transport_t *old_transport = NULL;
+
+  mp = get_managed_proxy_by_argv_and_type(proxy_argv, is_server);
+
+  if (!mp) { /* we haven't seen this proxy before */
+    managed_proxy_create(transport_list, proxy_argv, is_server);
+
+  } else { /* known proxy. add its transport to its transport list */
+    if (mp->got_hup) {
+      /* If the managed proxy we found is marked by a SIGHUP, it means
+         that it's not useless and should be kept. If it's marked for
+         removal, unmark it and increase the unconfigured proxies so
+         that we try to restart it if we need to. Afterwards, check if
+         a transport_t for 'transport' used to exist before the SIGHUP
+         and make sure it doesn't get deleted because we might reuse
+         it. */
+      if (mp->marked_for_removal) {
+        mp->marked_for_removal = 0;
+        unconfigured_proxies_n++;
+      }
+
+      SMARTLIST_FOREACH_BEGIN(transport_list, const char *, transport) {
+        old_transport = transport_get_by_name(transport);
+        if (old_transport)
+          old_transport->marked_for_removal = 0;
+      } SMARTLIST_FOREACH_END(transport);
+    }
+
+    SMARTLIST_FOREACH(transport_list, const char *, transport,
+                      add_transport_to_proxy(transport, mp));
+    free_execve_args(proxy_argv);
+  }
+}
+
+/** Frees the array of pointers in <b>arg</b> used as arguments to
+    execve(2). */
+static INLINE void
+free_execve_args(char **arg)
+{
+  char **tmp = arg;
+  while (*tmp) /* use the fact that the last element of the array is a
+                  NULL pointer to know when to stop freeing */
+    _tor_free(*tmp++);
+
+  tor_free(arg);
+}
+
+/** Tor will read its config.
+ *  Prepare the managed proxy list so that proxies not used in the new
+ *  config will shutdown, and proxies that need to spawn different
+ *  transports will do so. */
+void
+pt_prepare_proxy_list_for_config_read(void)
+{
+  if (!managed_proxy_list)
+    return;
+
+  SMARTLIST_FOREACH_BEGIN(managed_proxy_list, managed_proxy_t *, mp) {
+    /* Destroy unconfigured proxies. */
+    if (mp->conf_state != PT_PROTO_COMPLETED) {
+        managed_proxy_destroy(mp);
+        unconfigured_proxies_n--;
+        continue;
+    }
+
+    tor_assert(mp->conf_state == PT_PROTO_COMPLETED);
+
+    mp->marked_for_removal = 1;
+    mp->got_hup = 1;
+    SMARTLIST_FOREACH(mp->transports_to_launch, char *, t, tor_free(t));
+    smartlist_clear(mp->transports_to_launch);
+  } SMARTLIST_FOREACH_END(mp);
+
+  tor_assert(unconfigured_proxies_n == 0);
+}
+
+/** The tor config was read.
+ *  Destroy all managed proxies that were marked by a previous call to
+ *  prepare_proxy_list_for_config_read() and are not used by the new
+ *  config. */
+void
+sweep_proxy_list(void)
+{
+  if (!managed_proxy_list)
+    return;
+
+  SMARTLIST_FOREACH_BEGIN(managed_proxy_list, managed_proxy_t *, mp) {
+    if (mp->marked_for_removal) {
+      SMARTLIST_DEL_CURRENT(managed_proxy_list, mp);
+      managed_proxy_destroy(mp);
+    }
+  } SMARTLIST_FOREACH_END(mp);
+}
+
+/** Release all storage held by the pluggable transports subsystem. */
+void
+pt_free_all(void)
+{
+  if (managed_proxy_list) {
+    /* If the proxy is in PT_PROTO_COMPLETED, it has registered its
+       transports and it's the duty of the circuitbuild.c subsystem to
+       free them. Otherwise, it hasn't registered its transports yet
+       and we should free them here. */
+    SMARTLIST_FOREACH(managed_proxy_list, managed_proxy_t *, mp,
+                      managed_proxy_destroy(mp));
+
+    smartlist_free(managed_proxy_list);
+    managed_proxy_list=NULL;
+  }
+}
+
diff --git a/src/or/transports.h b/src/or/transports.h
new file mode 100644
index 0000000000..4a93387596
--- /dev/null
+++ b/src/or/transports.h
@@ -0,0 +1,105 @@
+/* Copyright (c) 2003-2004, Roger Dingledine
+ * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
+ * Copyright (c) 2007-2011, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+
+/**
+ * \file transports.h
+ * \brief Headers for transports.c
+ **/
+
+#ifndef TOR_TRANSPORTS_H
+#define TOR_TRANSPORTS_H
+
+void pt_kickstart_proxy(const smartlist_t *transport_list, char **proxy_argv,
+                        int is_server);
+
+#define pt_kickstart_client_proxy(tl, pa)  \
+  pt_kickstart_proxy(tl, pa, 0)
+#define pt_kickstart_server_proxy(tl, pa) \
+  pt_kickstart_proxy(tl, pa, 1)
+
+void pt_configure_remaining_proxies(void);
+
+int pt_proxies_configuration_pending(void);
+
+void pt_free_all(void);
+
+void pt_prepare_proxy_list_for_config_read(void);
+void sweep_proxy_list(void);
+
+#ifdef PT_PRIVATE
+/** State of the managed proxy configuration protocol. */
+enum pt_proto_state {
+  PT_PROTO_INFANT, /* was just born */
+  PT_PROTO_LAUNCHED, /* was just launched */
+  PT_PROTO_ACCEPTING_METHODS, /* accepting methods */
+  PT_PROTO_CONFIGURED, /* configured successfully */
+  PT_PROTO_COMPLETED, /* configure and registered its transports */
+  PT_PROTO_BROKEN
+};
+
+/** Structure containing information of a managed proxy. */
+typedef struct {
+  enum pt_proto_state conf_state; /* the current configuration state */
+  char **argv; /* the cli arguments of this proxy */
+  int conf_protocol; /* the configuration protocol version used */
+
+  int is_server; /* is it a server proxy? */
+
+  FILE *_stdout; /* a stream to its stdout
+                   (closed in managed_proxy_destroy()) */
+
+  int pid; /* The Process ID this managed proxy is using. */
+
+  /** Boolean: We are re-parsing our config, and we are going to
+   * remove this managed proxy if we don't find it any transport
+   * plugins that use it. */
+  unsigned int marked_for_removal : 1;
+
+  /** Boolean: We got a SIGHUP while this proxy was running. We use
+   * this flag to signify that this proxy might need to be restarted
+   * so that it can listen for other transports according to the new
+   * torrc. */
+  unsigned int got_hup : 1;
+
+  /* transports to-be-launched by this proxy */
+  smartlist_t *transports_to_launch;
+
+  /* The 'transports' list contains all the transports this proxy has
+     launched.
+
+     Before a managed_proxy_t reaches the PT_PROTO_COMPLETED phase,
+     this smartlist contains a 'transport_t' for every transport it
+     has launched.
+
+     When the managed_proxy_t reaches the PT_PROTO_COMPLETED phase, it
+     registers all its transports to the circuitbuild.c subsystem. At
+     that point the 'transport_t's are owned by the circuitbuild.c
+     subsystem.
+
+     To avoid carrying dangling 'transport_t's in this smartlist,
+     right before the managed_proxy_t reaches the PT_PROTO_COMPLETED
+     phase we replace all 'transport_t's with strings of their
+     transport names.
+
+     So, tl;dr:
+     When (conf_state != PT_PROTO_COMPLETED) this list carries
+     (transport_t *).
+     When (conf_state == PT_PROTO_COMPLETED) this list carries
+     (char *).
+   */
+  smartlist_t *transports;
+} managed_proxy_t;
+
+int parse_cmethod_line(const char *line, managed_proxy_t *mp);
+int parse_smethod_line(const char *line, managed_proxy_t *mp);
+
+int parse_version(const char *line, managed_proxy_t *mp);
+void parse_env_error(const char *line);
+void handle_proxy_line(const char *line, managed_proxy_t *mp);
+
+#endif
+
+#endif
+