6 files changed, 387 insertions, 0 deletions
diff --git a/src/feature/metrics/.may_include b/src/feature/metrics/.may_include
new file mode 100644
index 0000000000..424c745c12
--- /dev/null
+++ b/src/feature/metrics/.may_include
@@ -0,0 +1 @@
+*.h
diff --git a/src/feature/metrics/include.am b/src/feature/metrics/include.am
new file mode 100644
index 0000000000..0e875f43ad
--- /dev/null
+++ b/src/feature/metrics/include.am
@@ -0,0 +1,10 @@
+
+# ADD_C_FILE: INSERT SOURCES HERE.
+LIBTOR_APP_A_SOURCES +=		\
+	src/feature/metrics/metrics.c		\
+	src/feature/metrics/metrics_sys.c
+
+# ADD_C_FILE: INSERT HEADERS HERE.
+noinst_HEADERS +=		\
+	src/feature/metrics/metrics.h		\
+	src/feature/metrics/metrics_sys.h
diff --git a/src/feature/metrics/metrics.c b/src/feature/metrics/metrics.c
new file mode 100644
index 0000000000..9a72fe7145
--- /dev/null
+++ b/src/feature/metrics/metrics.c
@@ -0,0 +1,280 @@
+/* Copyright (c) 2007-2020, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+
+/**
+ * @file metrics.c
+ * @brief Metrics subsystem.
+ **/
+
+#include "orconfig.h"
+
+#include "core/or/or.h"
+
+#include "lib/encoding/confline.h"
+#include "lib/log/util_bug.h"
+#include "lib/malloc/malloc.h"
+#include "lib/metrics/metrics_store.h"
+#include "lib/net/resolve.h"
+#include "lib/string/printf.h"
+#include "lib/net/nettypes.h"
+#include "lib/net/address.h"
+
+#include "core/mainloop/connection.h"
+#include "core/or/connection_or.h"
+#include "core/or/connection_st.h"
+#include "core/or/policies.h"
+#include "core/or/port_cfg_st.h"
+#include "core/proto/proto_http.h"
+
+#include "feature/dircommon/directory.h"
+#include "feature/metrics/metrics.h"
+
+#include "app/config/config.h"
+#include "app/main/subsysmgr.h"
+
+/** Metrics format driver set by the MetricsPort option. */
+static metrics_format_t the_format = METRICS_FORMAT_PROMETHEUS;
+
+/** Return true iff the given peer address is allowed by our MetricsPortPolicy
+ * option that is is in that list. */
+static bool
+metrics_request_allowed(const tor_addr_t *peer_addr)
+{
+  tor_assert(peer_addr);
+
+  return metrics_policy_permits_address(peer_addr);
+}
+
+/** Helper: For a metrics port connection, write the HTTP response header
+ * using the data length passed. */
+static void
+write_metrics_http_response(const size_t data_len, connection_t *conn)
+{
+  char date[RFC1123_TIME_LEN+1];
+  buf_t *buf = buf_new_with_capacity(128 + data_len);
+
+  format_rfc1123_time(date, approx_time());
+  buf_add_printf(buf, "HTTP/1.0 200 OK\r\nDate: %s\r\n", date);
+  buf_add_printf(buf, "Content-Type: text/plain; charset=utf-8\r\n");
+  buf_add_printf(buf, "Content-Length: %" TOR_PRIuSZ "\r\n", data_len);
+  buf_add_string(buf, "\r\n");
+
+  connection_buf_add_buf(conn, buf);
+  buf_free(buf);
+}
+
+/** Return newly allocated buffer containing the output of all subsystems
+ * having metrics.
+ *
+ * This is used to output the content on the MetricsPort. */
+buf_t *
+metrics_get_output(const metrics_format_t fmt)
+{
+  buf_t *data = buf_new();
+
+  /* Go over all subsystems that exposes a metrics store. */
+  for (unsigned i = 0; i < n_tor_subsystems; ++i) {
+    const smartlist_t *stores;
+    const subsys_fns_t *sys = tor_subsystems[i];
+
+    /* Skip unsupported subsystems. */
+    if (!sys->supported) {
+      continue;
+    }
+
+    if (sys->get_metrics && (stores = sys->get_metrics())) {
+      SMARTLIST_FOREACH_BEGIN(stores, const metrics_store_t *, store) {
+        metrics_store_get_output(fmt, store, data);
+      } SMARTLIST_FOREACH_END(store);
+    }
+  }
+
+  return data;
+}
+
+/** Process what is in the inbuf of this connection of type metrics.
+ *
+ * Return 0 on success else -1 on error for which the connection is marked for
+ * close. */
+int
+metrics_connection_process_inbuf(connection_t *conn)
+{
+  int ret = -1;
+  char *headers = NULL, *command = NULL, *url = NULL;
+  const char *errmsg = NULL;
+
+  tor_assert(conn);
+  tor_assert(conn->type == CONN_TYPE_METRICS);
+
+  if (!metrics_request_allowed(&conn->addr)) {
+    /* Close connection. Don't bother returning anything if you are not
+     * allowed by being on the policy list. */
+    errmsg = NULL;
+    goto err;
+  }
+
+  const int http_status =
+    connection_fetch_from_buf_http(conn, &headers, 1024, NULL, NULL, 1024, 0);
+  if (http_status < 0) {
+    errmsg = "HTTP/1.0 400 Bad Request\r\n\r\n";
+    goto err;
+  } else if (http_status == 0) {
+    /* no HTTP request yet. */
+    ret = 0;
+    goto done;
+  }
+
+  const int cmd_status = parse_http_command(headers, &command, &url);
+  if (cmd_status < 0) {
+    errmsg = "HTTP/1.0 400 Bad Request\r\n\r\n";
+    goto err;
+  } else if (strcmpstart(command, "GET")) {
+    errmsg = "HTTP/1.0 405 Method Not Allowed\r\n\r\n";
+    goto err;
+  }
+  tor_assert(url);
+
+  /* Where we expect the query to come for. */
+#define EXPECTED_URL_PATH "/metrics"
+#define EXPECTED_URL_PATH_LEN (sizeof(EXPECTED_URL_PATH) - 1) /* No NUL */
+
+  if (!strcmpstart(url, EXPECTED_URL_PATH) &&
+      strlen(url) == EXPECTED_URL_PATH_LEN) {
+    buf_t *data = metrics_get_output(the_format);
+
+    write_metrics_http_response(buf_datalen(data), conn);
+    connection_buf_add_buf(conn, data);
+    buf_free(data);
+  } else {
+    errmsg = "HTTP/1.0 404 Not Found\r\n\r\n";
+    goto err;
+  }
+
+  ret = 0;
+  goto done;
+
+ err:
+  if (errmsg) {
+    log_info(LD_EDGE, "HTTP metrics error: saying %s", escaped(errmsg));
+    connection_buf_add(errmsg, strlen(errmsg), conn);
+  }
+  connection_mark_and_flush(conn);
+
+ done:
+  tor_free(headers);
+  tor_free(command);
+  tor_free(url);
+
+  return ret;
+}
+
+/** Parse metrics ports from options. On success, add the port to the ports
+ * list and return 0. On failure, set err_msg_out to a newly allocated string
+ * describing the problem and return -1. */
+int
+metrics_parse_ports(or_options_t *options, smartlist_t *ports,
+                    char **err_msg_out)
+{
+  int num_elems, ok = 0, ret = -1;
+  const char *addrport_str = NULL, *fmt_str = NULL;
+  smartlist_t *elems = NULL;
+  port_cfg_t *cfg = NULL;
+
+  tor_assert(options);
+  tor_assert(ports);
+
+  /* No metrics port to configure, just move on . */
+  if (!options->MetricsPort_lines) {
+    return 0;
+  }
+
+  elems = smartlist_new();
+
+  /* Split between the protocol and the address/port. */
+  num_elems = smartlist_split_string(elems,
+                                     options->MetricsPort_lines->value, " ",
+                                     SPLIT_SKIP_SPACE | SPLIT_IGNORE_BLANK, 2);
+  if (num_elems < 1) {
+    *err_msg_out = tor_strdup("MetricsPort is missing port.");
+    goto end;
+  }
+
+  addrport_str = smartlist_get(elems, 0);
+  if (num_elems >= 2) {
+    /* Parse the format if any. */
+    fmt_str = smartlist_get(elems, 1);
+    if (!strcasecmp(fmt_str, "prometheus")) {
+      the_format = METRICS_FORMAT_PROMETHEUS;
+    } else {
+      tor_asprintf(err_msg_out, "MetricsPort unknown format: %s", fmt_str);
+      goto end;
+    }
+  }
+
+  /* Port configuration with default address. */
+  cfg = port_cfg_new(0);
+  cfg->type = CONN_TYPE_METRICS_LISTENER;
+
+  /* Parse the port first. Then an address if any can be found. */
+  cfg->port = (int) tor_parse_long(addrport_str, 10, 0, 65535, &ok, NULL);
+  if (ok) {
+    tor_addr_parse(&cfg->addr, "127.0.0.1");
+  } else {
+    /* We probably have a host:port situation */
+    if (tor_addr_port_lookup(addrport_str, &cfg->addr,
+                             (uint16_t *) &cfg->port) < 0) {
+      *err_msg_out = tor_strdup("MetricsPort address/port failed to parse or "
+                                "resolve.");
+      goto end;
+    }
+  }
+  /* Add it to the ports list. */
+  smartlist_add(ports, cfg);
+
+  /* It is set. MetricsPort doesn't support the NoListen options or such that
+   * would prevent from being a real listener port. */
+  options->MetricsPort_set = 1;
+
+  /* Success. */
+  ret = 0;
+
+ end:
+  if (ret != 0) {
+    port_cfg_free(cfg);
+  }
+  SMARTLIST_FOREACH(elems, char *, e, tor_free(e));
+  smartlist_free(elems);
+  return ret;
+}
+
+/** Called when conn has gotten its socket closed. */
+int
+metrics_connection_reached_eof(connection_t *conn)
+{
+  tor_assert(conn);
+
+  log_info(LD_EDGE, "Metrics connection reached EOF. Closing.");
+  connection_mark_for_close(conn);
+  return 0;
+}
+
+/** Called when conn has no more bytes left on its outbuf. Return 0 indicating
+ * success. */
+int
+metrics_connection_finished_flushing(connection_t *conn)
+{
+  tor_assert(conn);
+  return 0;
+}
+
+/** Initialize the subsystem. */
+void
+metrics_init(void)
+{
+}
+
+/** Cleanup and free any global memory of this subsystem. */
+void
+metrics_cleanup(void)
+{
+}
diff --git a/src/feature/metrics/metrics.h b/src/feature/metrics/metrics.h
new file mode 100644
index 0000000000..e072519d10
--- /dev/null
+++ b/src/feature/metrics/metrics.h
@@ -0,0 +1,37 @@
+/* Copyright (c) 2020, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+
+/**
+ * @file metrics.h
+ * @brief Header for feature/metrics/metrics.c
+ **/
+
+#ifndef TOR_FEATURE_METRICS_METRICS_H
+#define TOR_FEATURE_METRICS_METRICS_H
+
+#include "lib/buf/buffers.h"
+#include "lib/container/smartlist.h"
+
+#include "app/config/or_options_st.h"
+
+#include "lib/metrics/metrics_common.h"
+
+struct connection_t;
+
+/* Initializer / Cleanup. */
+void metrics_init(void);
+void metrics_cleanup(void);
+
+/* Accessors. */
+buf_t *metrics_get_output(const metrics_format_t fmt);
+
+/* Connection. */
+int metrics_connection_process_inbuf(struct connection_t *conn);
+int metrics_connection_reached_eof(struct connection_t *conn);
+int metrics_connection_finished_flushing(struct connection_t *conn);
+
+/* Configuration. */
+int metrics_parse_ports(or_options_t *options, smartlist_t *ports,
+                        char **err_msg_out);
+
+#endif /* !defined(TOR_FEATURE_METRICS_METRICS_H) */
diff --git a/src/feature/metrics/metrics_sys.c b/src/feature/metrics/metrics_sys.c
new file mode 100644
index 0000000000..419318068e
--- /dev/null
+++ b/src/feature/metrics/metrics_sys.c
@@ -0,0 +1,37 @@
+/* Copyright (c) 2020, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+
+/**
+ * @file metrics_sys.c
+ * @brief Setup and tear down the metrics subsystem.
+ **/
+
+#include "lib/subsys/subsys.h"
+
+#include "feature/metrics/metrics.h"
+#include "feature/metrics/metrics_sys.h"
+
+static int
+subsys_metrics_initialize(void)
+{
+  metrics_init();
+  return 0;
+}
+
+static void
+subsys_metrics_shutdown(void)
+{
+  metrics_cleanup();
+}
+
+const subsys_fns_t sys_metrics = {
+  SUBSYS_DECLARE_LOCATION(),
+
+  .name = "metrics",
+  .supported = true,
+  .level = METRICS_SUBSYS_LEVEL,
+
+  .initialize = subsys_metrics_initialize,
+  .shutdown = subsys_metrics_shutdown,
+};
+
diff --git a/src/feature/metrics/metrics_sys.h b/src/feature/metrics/metrics_sys.h
new file mode 100644
index 0000000000..30c1b14836
--- /dev/null
+++ b/src/feature/metrics/metrics_sys.h
@@ -0,0 +1,22 @@
+/* Copyright (c) 2020, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+
+/**
+ * @file metrics_sys.h
+ * @brief Header for feature/metrics/metrics_sys.c
+ **/
+
+#ifndef TOR_FEATURE_METRICS_METRICS_SYS_H
+#define TOR_FEATURE_METRICS_METRICS_SYS_H
+
+extern const struct subsys_fns_t sys_metrics;
+
+/**
+ * Subsystem level for the metrics system.
+ *
+ * Defined here so that it can be shared between the real and stub
+ * definitions.
+ **/
+#define METRICS_SUBSYS_LEVEL (99)
+
+#endif /* !defined(TOR_FEATURE_METRICS_METRICS_SYS_H) */