conn: New Metrics listener port

If MetricsPort is defined, listen on it and handle the incoming request.

Signed-off-by: David Goulet <dgoulet@torproject.org>

2 files changed, 215 insertions, 11 deletions

diff --git a/src/feature/metrics/metrics.c b/src/feature/metrics/metrics.c
index 5f6fe776b7..886182bc90 100644
--- a/src/feature/metrics/metrics.c
+++ b/src/feature/metrics/metrics.c
@@ -8,25 +8,68 @@
 
 #include "orconfig.h"
 
-#include "lib/container/smartlist.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_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"
 
-/** Return newly allocated string containing the output of all subsystems
+/** 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. */
-char *
+buf_t *
 metrics_get_output(const metrics_format_t fmt)
 {
-  char *data;
-  smartlist_t *chunks = smartlist_new();
+  buf_t *data = buf_new();
 
   /* Go over all subsystems that exposes a metrics store. */
   for (unsigned i = 0; i < n_tor_subsystems; ++i) {
@@ -40,17 +83,164 @@ metrics_get_output(const metrics_format_t fmt)
 
     if (sys->get_metrics && (stores = sys->get_metrics())) {
       SMARTLIST_FOREACH_BEGIN(stores, const metrics_store_t *, store) {
-        smartlist_add(chunks, metrics_store_get_output(fmt, store));
+        metrics_store_get_output(fmt, store, data);
       } SMARTLIST_FOREACH_END(store);
     }
   }
 
-  data = smartlist_join_strings(chunks, "\n", 0, NULL);
+  return data;
+}
+
+/** Process what is in the inbuf of this connection of type metrics.
+ *
+ * Return 0 on success else -1 on error which will close the connection. */
+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 = fetch_from_buf_http(conn->inbuf, &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. */
+    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);
 
-  SMARTLIST_FOREACH(chunks, char *, c, tor_free(c));
-  smartlist_free(chunks);
+  /* 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 */
 
-  return data;
+  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);
+  }
+
+ 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;
 }
 
 /** Initialize the subsystem. */
diff --git a/src/feature/metrics/metrics.h b/src/feature/metrics/metrics.h
index a30c271bea..b4bbe28b27 100644
--- a/src/feature/metrics/metrics.h
+++ b/src/feature/metrics/metrics.h
@@ -9,13 +9,27 @@
 #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. */
-char *metrics_get_output(const metrics_format_t fmt);
+buf_t *metrics_get_output(const metrics_format_t fmt);
+
+/* Connection. */
+int metrics_connection_process_inbuf(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) */