Serve bandwidth file used in the next vote

When a directory authority is using a bandwidth file to obtain the
bandwidth values that will be included in the next vote, serve this
bandwidth file at /tor/status-vote/next/bandwidth.z.

src/feature/dircache/dircache.c

@@ -357,12 +357,15 @@ static int handle_get_robots(dir_connection_t *conn,
                                 const get_handler_args_t *args);
 static int handle_get_networkstatus_bridges(dir_connection_t *conn,
                                 const get_handler_args_t *args);
+static int handle_get_next_bandwidth(dir_connection_t *conn,
+                                     const get_handler_args_t *args);
 
 /** Table for handling GET requests. */
 static const url_table_ent_t url_table[] = {
   { "/tor/", 0, handle_get_frontpage },
   { "/tor/status-vote/current/consensus", 1, handle_get_current_consensus },
   { "/tor/status-vote/current/", 1, handle_get_status_vote },
+  { "/tor/status-vote/next/bandwidth", 0, handle_get_next_bandwidth },
   { "/tor/status-vote/next/", 1, handle_get_status_vote },
   { "/tor/micro/d/", 1, handle_get_microdesc },
   { "/tor/server/", 1, handle_get_descriptor },
@@ -1438,6 +1441,27 @@ handle_get_networkstatus_bridges(dir_connection_t *conn,
   return 0;
 }
 
+/** Helper function for GET the bandwidth file used for the next vote */
+static int
+handle_get_next_bandwidth(dir_connection_t *conn,
+                          const get_handler_args_t *args)
+{
+  (void)args;
+  log_debug(LD_DIR, "Getting next bandwidth.");
+  const or_options_t *options = get_options();
+  if (options->V3BandwidthsFile) {
+    int lifetime = 60;
+    char *bandwidth =  read_file_to_str(options->V3BandwidthsFile, 0, NULL);
+    size_t len = strlen(bandwidth);
+    write_http_response_header(conn, len, NO_METHOD, lifetime);
+    connection_buf_add(bandwidth, len, TO_CONN(conn));
+    tor_free(bandwidth);
+  } else {
+    write_short_http_response(conn, 404, "Not found");
+  }
+  return 0;
+}
+
 /** Helper function for GET robots.txt or /tor/robots.txt */
 static int
 handle_get_robots(dir_connection_t *conn, const get_handler_args_t *args)

src/test/test_dir_handle_get.c

@@ -2217,6 +2217,31 @@ test_dir_handle_get_status_vote_next_authority_not_found(void* data)
     tor_free(header);
 }
 
+static void
+test_dir_handle_get_status_vote_next_bandwidth_not_found(void* data)
+{
+  dir_connection_t *conn = NULL;
+  char *header = NULL;
+  (void) data;
+
+  MOCK(connection_write_to_buf_impl_, connection_write_to_buf_mock);
+
+  conn = new_dir_conn();
+
+  tt_int_op(0, OP_EQ, directory_handle_command_get(conn,
+    GET("/tor/status-vote/next/bandwdith"), NULL, 0));
+
+  fetch_from_buf_http(TO_CONN(conn)->outbuf, &header, MAX_HEADERS_SIZE,
+                      NULL, NULL, 1, 0);
+  tt_assert(header);
+  tt_str_op(NOT_FOUND, OP_EQ, header);
+
+  done:
+    UNMOCK(connection_write_to_buf_impl_);
+    connection_free_minimal(TO_CONN(conn));
+    tor_free(header);
+}
+
 NS_DECL(const char*,
 dirvote_get_pending_consensus, (consensus_flavor_t flav));
 
@@ -2454,6 +2479,55 @@ test_dir_handle_get_status_vote_next_authority(void* data)
     dirvote_free_all();
 }
 
+static void
+test_dir_handle_get_status_vote_next_bandwidth(void* data)
+{
+  dir_connection_t *conn = NULL;
+  char *header = NULL, *body = NULL;
+  size_t body_used = 0;
+  (void) data;
+
+  const char *content =
+    "1541171221\n"
+    "node_id=$68A483E05A2ABDCA6DA5A3EF8DB5177638A27F80 "
+    "master_key_ed25519=YaqV4vbvPYKucElk297eVdNArDz9HtIwUoIeo0+cVIpQ "
+    "bw=760 nick=Test time=2018-05-08T16:13:26\n";
+
+  init_mock_options();
+  MOCK(get_options, mock_get_options);
+  mock_options->V3BandwidthsFile = tor_strdup(
+    get_fname_rnd("V3BandwidthsFile")
+  );
+
+  write_str_to_file(mock_options->V3BandwidthsFile, content, 0);
+
+  MOCK(connection_write_to_buf_impl_, connection_write_to_buf_mock);
+
+  conn = new_dir_conn();
+  tt_int_op(0, OP_EQ, directory_handle_command_get(conn,
+    GET("/tor/status-vote/next/bandwidth"), NULL, 0));
+
+  fetch_from_buf_http(TO_CONN(conn)->outbuf, &header, MAX_HEADERS_SIZE,
+                      &body, &body_used, strlen(content)+1, 0);
+
+  tt_assert(header);
+  tt_ptr_op(strstr(header, "HTTP/1.0 200 OK\r\n"), OP_EQ, header);
+  tt_assert(strstr(header, "Content-Type: text/plain\r\n"));
+  tt_assert(strstr(header, "Content-Encoding: identity\r\n"));
+  tt_assert(strstr(header, "Content-Length: 167\r\n"));
+
+  tt_int_op(body_used, OP_EQ, strlen(body));
+  tt_str_op(content, OP_EQ, body);
+
+  done:
+    UNMOCK(get_options);
+    UNMOCK(connection_write_to_buf_impl_);
+    connection_free_minimal(TO_CONN(conn));
+    tor_free(header);
+    tor_free(body);
+    or_options_free(mock_options); mock_options = NULL;
+}
+
 static void
 test_dir_handle_get_status_vote_current_authority(void* data)
 {
@@ -2627,6 +2701,8 @@ struct testcase_t dir_handle_get_tests[] = {
   DIR_HANDLE_CMD(status_vote_current_authority, 0),
   DIR_HANDLE_CMD(status_vote_next_authority_not_found, 0),
   DIR_HANDLE_CMD(status_vote_next_authority, 0),
+  DIR_HANDLE_CMD(status_vote_next_bandwidth_not_found, 0),
+  DIR_HANDLE_CMD(status_vote_next_bandwidth, 0),
   DIR_HANDLE_CMD(status_vote_current_consensus_ns_not_enough_sigs, TT_FORK),
   DIR_HANDLE_CMD(status_vote_current_consensus_ns_not_found, TT_FORK),
   DIR_HANDLE_CMD(status_vote_current_consensus_too_old, TT_FORK),