Raise libevent dependency to 2.0.10-stable or newer

Only some very ancient distributions don't ship with Libevent 2 anymore,
even the oldest supported Ubuntu LTS version has it. This allows us to
get rid of a lot of compat code.

src/common/compat_libevent.c

@@ -19,15 +19,11 @@
 #include "util.h"
 #include "torlog.h"
 
-#ifdef HAVE_EVENT2_EVENT_H
 #include <event2/event.h>
 #include <event2/thread.h>
 #ifdef USE_BUFFEREVENTS
 #include <event2/bufferevent.h>
 #endif
-#else
-#include <event.h>
-#endif
 
 /** A string which, if it appears in a libevent log, should be ignored. */
 static const char *suppress_msg = NULL;
@@ -69,6 +65,7 @@ configure_libevent_logging(void)
 {
   event_set_log_callback(libevent_logging_callback);
 }
+
 /** Ignore any libevent log message that contains <b>msg</b>. */
 void
 suppress_libevent_log_msg(const char *msg)
@@ -76,44 +73,6 @@ suppress_libevent_log_msg(const char *msg)
   suppress_msg = msg;
 }
 
-#ifndef HAVE_EVENT2_EVENT_H
-/** Work-alike replacement for event_new() on pre-Libevent-2.0 systems. */
-struct event *
-tor_event_new(struct event_base *base, int sock, short what,
-              void (*cb)(int, short, void *), void *arg)
-{
-  struct event *e = tor_malloc_zero(sizeof(struct event));
-  event_set(e, sock, what, cb, arg);
-  if (! base)
-    base = tor_libevent_get_base();
-  event_base_set(base, e);
-  return e;
-}
-/** Work-alike replacement for evtimer_new() on pre-Libevent-2.0 systems. */
-struct event *
-tor_evtimer_new(struct event_base *base,
-                void (*cb)(int, short, void *), void *arg)
-{
-  return tor_event_new(base, -1, 0, cb, arg);
-}
-/** Work-alike replacement for evsignal_new() on pre-Libevent-2.0 systems. */
-struct event *
-tor_evsignal_new(struct event_base * base, int sig,
-                 void (*cb)(int, short, void *), void *arg)
-{
-  return tor_event_new(base, sig, EV_SIGNAL|EV_PERSIST, cb, arg);
-}
-/** Work-alike replacement for event_free() on pre-Libevent-2.0 systems,
- * except tolerate tor_event_free(NULL). */
-void
-tor_event_free(struct event *ev)
-{
-  if (ev == NULL)
-    return;
-  event_del(ev);
-  tor_free(ev);
-}
-#else
 /* Wrapper for event_free() that tolerates tor_event_free(NULL) */
 void
 tor_event_free(struct event *ev)
@@ -122,7 +81,6 @@ tor_event_free(struct event *ev)
     return;
   event_free(ev);
 }
-#endif
 
 /** Global event base for use by the main thread. */
 static struct event_base *the_event_base = NULL;
@@ -158,7 +116,6 @@ tor_libevent_initialize(tor_libevent_cfg *torcfg)
   /* some paths below don't use torcfg, so avoid unused variable warnings */
   (void)torcfg;
 
-#ifdef HAVE_EVENT2_EVENT_H
   {
     int attempts = 0;
     int using_threads;
@@ -190,16 +147,12 @@ tor_libevent_initialize(tor_libevent_cfg *torcfg)
       event_config_set_flag(cfg, EVENT_BASE_FLAG_NOLOCK);
     }
 
-#if defined(LIBEVENT_VERSION_NUMBER) && LIBEVENT_VERSION_NUMBER >= V(2,0,7)
     if (torcfg->num_cpus > 0)
       event_config_set_num_cpus_hint(cfg, torcfg->num_cpus);
-#endif
 
-#if LIBEVENT_VERSION_NUMBER >= V(2,0,9)
     /* We can enable changelist support with epoll, since we don't give
      * Libevent any dup'd fds.  This lets us avoid some syscalls. */
     event_config_set_flag(cfg, EVENT_BASE_FLAG_EPOLL_USE_CHANGELIST);
-#endif
 
     the_event_base = event_base_new_with_config(cfg);
 
@@ -223,9 +176,6 @@ tor_libevent_initialize(tor_libevent_cfg *torcfg)
       goto retry;
     }
   }
-#else
-  the_event_base = event_init();
-#endif
 
   if (!the_event_base) {
     /* LCOV_EXCL_START */
@@ -255,62 +205,7 @@ tor_libevent_get_base, (void))
 const char *
 tor_libevent_get_method(void)
 {
-#ifdef HAVE_EVENT2_EVENT_H
   return event_base_get_method(the_event_base);
-#else
-  return event_get_method();
-#endif
-}
-
-/** Return the le_version_t for the version of libevent specified in the
- * string <b>v</b>.  If the version is very new or uses an unrecognized
- * version, format, return LE_OTHER. */
-STATIC le_version_t
-tor_decode_libevent_version(const char *v)
-{
-  unsigned major, minor, patchlevel;
-  char c, e, extra;
-  int fields;
-
-  /* Try the new preferred "1.4.11-stable" format.
-   * Also accept "1.4.14b-stable". */
-  fields = tor_sscanf(v, "%u.%u.%u%c%c", &major, &minor, &patchlevel, &c, &e);
-  if (fields == 3 ||
-      ((fields == 4 || fields == 5 ) && (c == '-' || c == '_')) ||
-      (fields == 5 && TOR_ISALPHA(c) && (e == '-' || e == '_'))) {
-    return V(major,minor,patchlevel);
-  }
-
-  /* Try the old "1.3e" format. */
-  fields = tor_sscanf(v, "%u.%u%c%c", &major, &minor, &c, &extra);
-  if (fields == 3 && TOR_ISALPHA(c)) {
-    return V_OLD(major, minor, c);
-  } else if (fields == 2) {
-    return V(major, minor, 0);
-  }
-
-  return LE_OTHER;
-}
-
-/** Return an integer representing the binary interface of a Libevent library.
- * Two different versions with different numbers are sure not to be binary
- * compatible.  Two different versions with the same numbers have a decent
- * chance of binary compatibility.*/
-STATIC int
-le_versions_compatibility(le_version_t v)
-{
-  if (v == LE_OTHER)
-    return 0;
-  if (v < V_OLD(1,0,'c'))
-    return 1;
-  else if (v < V(1,4,0))
-    return 2;
-  else if (v < V(1,4,99))
-    return 3;
-  else if (v < V(2,0,1))
-    return 4;
-  else /* Everything 2.0 and later should be compatible. */
-    return 5;
 }
 
 /** Return a string representation of the version of the currently running
@@ -321,101 +216,14 @@ tor_libevent_get_version_str(void)
   return event_get_version();
 }
 
-#if defined(LIBEVENT_VERSION)
-#define HEADER_VERSION LIBEVENT_VERSION
-#elif defined(_EVENT_VERSION)
-#define HEADER_VERSION _EVENT_VERSION
-#endif
-
 /** Return a string representation of the version of Libevent that was used
 * at compilation time. */
 const char *
 tor_libevent_get_header_version_str(void)
 {
-  return HEADER_VERSION;
+  return LIBEVENT_VERSION;
 }
 
-/** See whether the headers we were built against differ from the library we
- * linked against so much that we're likely to crash.  If so, warn the
- * user. */
-void
-tor_check_libevent_header_compatibility(void)
-{
-  (void) le_versions_compatibility;
-  (void) tor_decode_libevent_version;
-
-  /* In libevent versions before 2.0, it's hard to keep binary compatibility
-   * between upgrades, and unpleasant to detect when the version we compiled
-   * against is unlike the version we have linked against. Here's how. */
-#if defined(HEADER_VERSION)
-  /* We have a header-file version and a function-call version. Easy. */
-  if (strcmp(HEADER_VERSION, event_get_version())) {
-    le_version_t v1, v2;
-    int compat1 = -1, compat2 = -1;
-    int verybad;
-    v1 = tor_decode_libevent_version(HEADER_VERSION);
-    v2 = tor_decode_libevent_version(event_get_version());
-    compat1 = le_versions_compatibility(v1);
-    compat2 = le_versions_compatibility(v2);
-
-    verybad = compat1 != compat2;
-
-    tor_log(verybad ? LOG_WARN : LOG_NOTICE,
-        LD_GENERAL, "We were compiled with headers from version %s "
-        "of Libevent, but we're using a Libevent library that says it's "
-        "version %s.", HEADER_VERSION, event_get_version());
-    if (verybad)
-      log_warn(LD_GENERAL, "This will almost certainly make Tor crash.");
-    else
-      log_info(LD_GENERAL, "I think these versions are binary-compatible.");
-  }
-#else
-  /* event_get_version but no _EVENT_VERSION.  We might be in 1.4.0-beta or
-     earlier, where that's normal.  To see whether we were compiled with an
-     earlier version, let's see whether the struct event defines MIN_HEAP_IDX.
-  */
-#ifdef HAVE_STRUCT_EVENT_MIN_HEAP_IDX
-  /* The header files are 1.4.0-beta or later. If the version is not
-   * 1.4.0-beta, we are incompatible. */
-  {
-    if (strcmp(event_get_version(), "1.4.0-beta")) {
-      log_warn(LD_GENERAL, "It's a little hard to tell, but you seem to have "
-               "Libevent 1.4.0-beta header files, whereas you have linked "
-               "against Libevent %s.  This will probably make Tor crash.",
-               event_get_version());
-    }
-  }
-#else
-  /* Our headers are 1.3e or earlier. If the library version is not 1.4.x or
-     later, we're probably fine. */
-  {
-    const char *v = event_get_version();
-    if ((v[0] == '1' && v[2] == '.' && v[3] > '3') || v[0] > '1') {
-      log_warn(LD_GENERAL, "It's a little hard to tell, but you seem to have "
-               "Libevent header file from 1.3e or earlier, whereas you have "
-               "linked against Libevent %s.  This will probably make Tor "
-               "crash.", event_get_version());
-    }
-  }
-#endif
-
-  /* Your libevent is ancient. */
-#endif
-}
-
-/*
-  If possible, we're going to try to use Libevent's periodic timer support,
-  since it does a pretty good job of making sure that periodic events get
-  called exactly M seconds apart, rather than starting each one exactly M
-  seconds after the time that the last one was run.
- */
-#ifdef HAVE_EVENT2_EVENT_H
-#define HAVE_PERIODIC
-#define PERIODIC_FLAGS EV_PERSIST
-#else
-#define PERIODIC_FLAGS 0
-#endif
-
 /** Represents a timer that's run every N microseconds by Libevent. */
 struct periodic_timer_t {
   /** Underlying event used to implement this periodic event. */
@@ -424,11 +232,6 @@ struct periodic_timer_t {
   void (*cb)(struct periodic_timer_t *, void *);
   /** User-supplied data for the callback */
   void *data;
-#ifndef HAVE_PERIODIC
-  /** If Libevent doesn't know how to invoke events every N microseconds,
-   * we'll need to remember the timeout interval here. */
-  struct timeval tv;
-#endif
 };
 
 /** Libevent callback to implement a periodic event. */
@@ -438,10 +241,6 @@ periodic_timer_cb(evutil_socket_t fd, short what, void *arg)
   periodic_timer_t *timer = arg;
   (void) what;
   (void) fd;
-#ifndef HAVE_PERIODIC
-  /** reschedule the event as needed. */
-  event_add(timer->ev, &timer->tv);
-#endif
   timer->cb(timer, timer->data);
 }
 
@@ -459,16 +258,13 @@ periodic_timer_new(struct event_base *base,
   tor_assert(tv);
   tor_assert(cb);
   timer = tor_malloc_zero(sizeof(periodic_timer_t));
-  if (!(timer->ev = tor_event_new(base, -1, PERIODIC_FLAGS,
+  if (!(timer->ev = tor_event_new(base, -1, EV_PERSIST,
                                   periodic_timer_cb, timer))) {
     tor_free(timer);
     return NULL;
   }
   timer->cb = cb;
   timer->data = data;
-#ifndef HAVE_PERIODIC
-  memcpy(&timer->tv, tv, sizeof(struct timeval));
-#endif
   event_add(timer->ev, (struct timeval *)tv); /*drop const for old libevent*/
   return timer;
 }
@@ -539,7 +335,6 @@ int
 tor_init_libevent_rng(void)
 {
   int rv = 0;
-#ifdef HAVE_EVUTIL_SECURE_RNG_INIT
   char buf[256];
   if (evutil_secure_rng_init() < 0) {
     rv = -1;
@@ -547,7 +342,6 @@ tor_init_libevent_rng(void)
   crypto_rand(buf, 32);
   evutil_secure_rng_add_bytes(buf, 32);
   evutil_secure_rng_get_bytes(buf, sizeof(buf));
-#endif
   return rv;
 }
 

src/common/compat_libevent.h

@@ -15,32 +15,17 @@ struct ev_token_bucket_cfg;
 struct bufferevent_rate_limit_group;
 #endif
 
-#ifdef HAVE_EVENT2_EVENT_H
 #include <event2/util.h>
-#elif !defined(EVUTIL_SOCKET_DEFINED)
-#define EVUTIL_SOCKET_DEFINED
-#define evutil_socket_t int
-#endif
 
 void configure_libevent_logging(void);
 void suppress_libevent_log_msg(const char *msg);
 
-#ifdef HAVE_EVENT2_EVENT_H
 #define tor_event_new     event_new
 #define tor_evtimer_new   evtimer_new
 #define tor_evsignal_new  evsignal_new
 #define tor_evdns_add_server_port(sock, tcp, cb, data) \
   evdns_add_server_port_with_base(tor_libevent_get_base(), \
   (sock),(tcp),(cb),(data));
-#else
-struct event *tor_event_new(struct event_base * base, evutil_socket_t sock,
-           short what, void (*cb)(evutil_socket_t, short, void *), void *arg);
-struct event *tor_evtimer_new(struct event_base * base,
-            void (*cb)(evutil_socket_t, short, void *), void *arg);
-struct event *tor_evsignal_new(struct event_base * base, int sig,
-            void (*cb)(evutil_socket_t, short, void *), void *arg);
-#define tor_evdns_add_server_port evdns_add_server_port
-#endif
 
 void tor_event_free(struct event *ev);
 
@@ -99,9 +84,7 @@ void tor_gettimeofday_cached_monotonic(struct timeval *tv);
     byte is unused.
 
     This is equivalent to the format of LIBEVENT_VERSION_NUMBER on Libevent
-    2.0.1 or later.  For versions of Libevent before 1.4.0, which followed the
-    format of "1.0, 1.0a, 1.0b", we define 1.0 to be equivalent to 1.0.0, 1.0a
-    to be equivalent to 1.0.1, and so on.
+    2.0.1 or later.
 */
 typedef uint32_t le_version_t;
 
@@ -109,23 +92,10 @@ typedef uint32_t le_version_t;
 /** Macros: returns the number of a libevent version as a le_version_t */
 #define V(major, minor, patch) \
   (((major) << 24) | ((minor) << 16) | ((patch) << 8))
-#define V_OLD(major, minor, patch) \
-  V((major), (minor), (patch)-'a'+1)
 /** @} */
 
-/** Represetns a version of libevent so old we can't figure out what version
- * it is. */
-#define LE_OLD V(0,0,0)
-/** Represents a version of libevent so weird we can't figure out what version
- * it is. */
-#define LE_OTHER V(0,0,99)
-
 STATIC void
 libevent_logging_callback(int severity, const char *msg);
-STATIC le_version_t
-tor_decode_libevent_version(const char *v);
-STATIC int
-le_versions_compatibility(le_version_t v);
 #endif
 
 #endif

src/common/procmon.c

@@ -10,11 +10,7 @@
 
 #include "util.h"
 
-#ifdef HAVE_EVENT2_EVENT_H
 #include <event2/event.h>
-#else
-#include <event.h>
-#endif
 
 #ifdef HAVE_SIGNAL_H
 #include <signal.h>
@@ -164,11 +160,7 @@ tor_validate_process_specifier(const char *process_spec,
 }
 
 /* XXXX we should use periodic_timer_new() for this stuff */
-#ifdef HAVE_EVENT2_EVENT_H
 #define PERIODIC_TIMER_FLAGS EV_PERSIST
-#else
-#define PERIODIC_TIMER_FLAGS (0)
-#endif
 
 /* DOCDOC poll_interval_tv */
 static struct timeval poll_interval_tv = {15, 0};
@@ -331,10 +323,6 @@ tor_process_monitor_poll_cb(evutil_socket_t unused1, short unused2,
 
   if (its_dead_jim) {
     procmon->cb(procmon->cb_arg);
-#ifndef HAVE_EVENT2_EVENT_H
-  } else {
-    evtimer_add(procmon->e, &poll_interval_tv);
-#endif
   }
 }
 #endif

src/common/timers.c

@@ -38,11 +38,7 @@
 #include "torlog.h"
 #include "util.h"
 
-#ifdef HAVE_EVENT2_EVENT_H
 #include <event2/event.h>
-#else
-#include <event.h>
-#endif
 
 struct timeout_cb {
   timer_cb_fn_t cb;