Merge branch 'collectd-5.7'

[collectd.git] / src / write_prometheus.c

diff --git a/src/write_prometheus.c b/src/write_prometheus.c
index 6fb5a86..61c43fe 100644 (file)
--- a/src/write_prometheus.c
+++ b/src/write_prometheus.c
@@ -37,7 +37,7 @@
 #include <microhttpd.h>
 
 #ifndef PROMETHEUS_DEFAULT_STALENESS_DELTA
-#define PROMETHEUS_DEFAULT_STALENESS_DELTA TIME_T_TO_CDTIME_T(300)
+#define PROMETHEUS_DEFAULT_STALENESS_DELTA TIME_T_TO_CDTIME_T_STATIC(300)
 #endif
 
 #define VARINT_UINT32_BYTES 5
@@ -98,6 +98,43 @@ static void format_protobuf(ProtobufCBuffer *buffer) {
   pthread_mutex_unlock(&metrics_lock);
 }
 
+static char const *escape_label_value(char *buffer, size_t buffer_size,
+                                      char const *value) {
+  /* shortcut for values that don't need escaping. */
+  if (strpbrk(value, "\n\"\\") == NULL)
+    return value;
+
+  size_t value_len = strlen(value);
+  size_t buffer_len = 0;
+
+  for (size_t i = 0; i < value_len; i++) {
+    switch (value[i]) {
+    case '\n':
+    case '"':
+    case '\\':
+      if ((buffer_size - buffer_len) < 3) {
+        break;
+      }
+      buffer[buffer_len] = '\\';
+      buffer[buffer_len + 1] = (value[i] == '\n') ? 'n' : value[i];
+      buffer_len += 2;
+      break;
+
+    default:
+      if ((buffer_size - buffer_len) < 2) {
+        break;
+      }
+      buffer[buffer_len] = value[i];
+      buffer_len++;
+      break;
+    }
+  }
+
+  assert(buffer_len < buffer_size);
+  buffer[buffer_len] = 0;
+  return buffer;
+}
+
 /* format_labels formats a metric's labels in Prometheus-compatible format. This
  * format looks like this:
  *
@@ -109,16 +146,22 @@ static char *format_labels(char *buffer, size_t buffer_size,
   assert(m->n_label >= 1);
   assert(m->n_label <= 3);
 
-#define LABEL_BUFFER_SIZE (2 * DATA_MAX_NAME_LEN + 4)
+#define LABEL_KEY_SIZE DATA_MAX_NAME_LEN
+#define LABEL_VALUE_SIZE (2 * DATA_MAX_NAME_LEN - 1)
+#define LABEL_BUFFER_SIZE (LABEL_KEY_SIZE + LABEL_VALUE_SIZE + 4)
 
   char *labels[3] = {
       (char[LABEL_BUFFER_SIZE]){0}, (char[LABEL_BUFFER_SIZE]){0},
       (char[LABEL_BUFFER_SIZE]){0},
   };
 
-  for (size_t i = 0; i < m->n_label; i++)
+  /* N.B.: the label *names* are hard-coded by this plugin and therefore we
+   * know that they are sane. */
+  for (size_t i = 0; i < m->n_label; i++) {
+    char value[LABEL_VALUE_SIZE];
     ssnprintf(labels[i], LABEL_BUFFER_SIZE, "%s=\"%s\"", m->label[i]->name,
-              m->label[i]->value);
+              escape_label_value(value, sizeof(value), m->label[i]->value));
+  }
 
   strjoin(buffer, buffer_size, labels, m->n_label, ",");
   return buffer;
@@ -210,12 +253,11 @@ static int http_handler(void *cls, struct MHD_Connection *connection,
   else
     format_text(buffer);
 
-  struct MHD_Response *res =
 #if defined(MHD_VERSION) && MHD_VERSION >= 0x00090500
-    MHD_create_response_from_buffer(
+  struct MHD_Response *res = MHD_create_response_from_buffer(
       simple.len, simple.data, MHD_RESPMEM_MUST_COPY);
 #else
-    MHD_create_response_from_data(
+  struct MHD_Response *res = MHD_create_response_from_data(
       simple.len, simple.data, /* must_free = */ 0, /* must_copy = */ 1);
 #endif
   MHD_add_response_header(res, MHD_HTTP_HEADER_CONTENT_TYPE,
@@ -637,8 +679,8 @@ static char *metric_family_name(data_set_t const *ds, value_list_t const *vl,
 /* metric_family_get looks up the matching metric family, allocating it if
  * necessary. */
 static Io__Prometheus__Client__MetricFamily *
-metric_family_get(data_set_t const *ds, value_list_t const *vl,
-                  size_t ds_index) {
+metric_family_get(data_set_t const *ds, value_list_t const *vl, size_t ds_index,
+                  _Bool allocate) {
   char *name = metric_family_name(ds, vl, ds_index);
   if (name == NULL) {
     ERROR("write_prometheus plugin: Allocating metric family name failed.");
@@ -652,6 +694,11 @@ metric_family_get(data_set_t const *ds, value_list_t const *vl,
     return fam;
   }
 
+  if (!allocate) {
+    sfree(name);
+    return NULL;
+  }
+
   fam = metric_family_create(name, ds, vl, ds_index);
   if (fam == NULL) {
     ERROR("write_prometheus plugin: Allocating metric family failed.");
@@ -733,7 +780,8 @@ static int prom_write(data_set_t const *ds, value_list_t const *vl,
   pthread_mutex_lock(&metrics_lock);
 
   for (size_t i = 0; i < ds->ds_num; i++) {
-    Io__Prometheus__Client__MetricFamily *fam = metric_family_get(ds, vl, i);
+    Io__Prometheus__Client__MetricFamily *fam =
+        metric_family_get(ds, vl, i, /* allocate = */ 1);
     if (fam == NULL)
       continue;
 
@@ -759,7 +807,8 @@ static int prom_missing(value_list_t const *vl,
   pthread_mutex_lock(&metrics_lock);
 
   for (size_t i = 0; i < ds->ds_num; i++) {
-    Io__Prometheus__Client__MetricFamily *fam = metric_family_get(ds, vl, i);
+    Io__Prometheus__Client__MetricFamily *fam =
+        metric_family_get(ds, vl, i, /* allocate = */ 0);
     if (fam == NULL)
       continue;
 
@@ -768,6 +817,7 @@ static int prom_missing(value_list_t const *vl,
       ERROR("write_prometheus plugin: Deleting a metric in family \"%s\" "
             "failed with status %d",
             fam->name, status);
+
       continue;
     }
 
@@ -820,5 +870,3 @@ void module_register() {
                           /* user data = */ NULL);
   plugin_register_shutdown("write_prometheus", prom_shutdown);
 }
-
-/* vim: set sw=2 sts=2 et fdm=marker : */