Do not publish the "git-XXX" tag in server descriptors

Instead, allow packagers to put a 'TOR_BUILD_TAG' field in the
server descriptor to indicate a platform-specific value, if they
need to.  (According to weasel, this was his use for the git- tag
previously.)

This is part of 2988

changes/bug2988

@@ -3,4 +3,8 @@
       operating system's name (e.g., "Linux", "Darwin", "Windows 7"),
       and not its service pack level (for Windows), or its CPU
       architecture (for Unix). This is part of ticket 2988.
-
+    - Do not include the (git-XYZ) tag in published server descriptor
+      platform lines. This is part of ticket 2988.
+    - Allow packagers to insert an extra string in server descriptor
+      platform lines by setting the preprocessor variable TOR_BUILD_TAG.
+      This is part of ticket 2988.

src/or/config.c

@@ -783,6 +783,7 @@ extern const char tor_git_revision[]; /* from tor_main.c */
 
 /** The version of this Tor process, as parsed. */
 static char *the_tor_version = NULL;
+static char *the_short_tor_version = NULL;
 
 /** Return the current Tor version. */
 const char *
@@ -790,14 +791,31 @@ get_version(void)
 {
   if (the_tor_version == NULL) {
     if (strlen(tor_git_revision)) {
-      tor_asprintf(&the_tor_version, "%s (git-%s)", VERSION, tor_git_revision);
+      tor_asprintf(&the_tor_version, "%s (git-%s)", get_short_version(),
+                   tor_git_revision);
     } else {
-      the_tor_version = tor_strdup(VERSION);
+      the_tor_version = tor_strdup(get_short_version());
     }
   }
   return the_tor_version;
 }
 
+/** Return the current Tor version, without any git tag. */
+const char *
+get_short_version(void)
+{
+
+  if (the_short_tor_version == NULL) {
+#ifdef TOR_BUILD_TAG
+    tor_asprintf(&the_short_tor_version, "%s (%s)", VERSION, TOR_BUILD_TAG);
+#else
+    the_short_tor_version = tor_strdup(VERSION);
+#endif
+  }
+  return the_short_tor_version;
+}
+
+
 /** Release additional memory allocated in options
  */
 static void

src/or/config.h

@@ -22,6 +22,7 @@ const char *safe_str(const char *address);
 const char *escaped_safe_str_client(const char *address);
 const char *escaped_safe_str(const char *address);
 const char *get_version(void);
+const char *get_short_version(void);
 
 int config_get_lines(const char *string, config_line_t **result, int extended);
 void config_free_lines(config_line_t *front);

src/or/router.c

@@ -1949,7 +1949,7 @@ router_guess_address_from_dir_headers(uint32_t *guess)
 void
 get_platform_str(char *platform, size_t len)
 {
-  tor_snprintf(platform, len, "Tor %s on %s", get_version(), get_uname());
+  tor_snprintf(platform, len, "Tor %s on %s", get_short_version(), get_uname());
 }
 
 /* XXX need to audit this thing and count fenceposts. maybe