Rename the network collector to netdev.

Resolves #14. For consistency with node_exporter, and with other
network-related collectors.

1 files changed, 202 insertions, 0 deletions

diff --git a/netdev.c b/netdev.c
new file mode 100644
index 0000000..b8f20b6
--- /dev/null
+++ b/netdev.c
@@ -0,0 +1,202 @@
+/*
+ * Copyright 2018 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define _POSIX_C_SOURCE 200809L
+
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "collector.h"
+#include "util.h"
+
+// size of input buffer for paths and lines
+#define BUF_SIZE 256
+// maximum number of columns in the file
+#define MAX_COLUMNS 32
+
+// default list of interfaces to exclude
+#define DEFAULT_EXCLUDE "lo"
+
+static void *netdev_init(int argc, char *argv[]);
+static void netdev_collect(scrape_req *req, void *ctx);
+
+const struct collector netdev_collector = {
+  .name = "netdev",
+  .collect = netdev_collect,
+  .init = netdev_init,
+  .has_args = true,
+};
+
+struct netdev_context {
+  size_t ncolumns;
+  char *columns[MAX_COLUMNS];
+  struct slist *include;
+  struct slist *exclude;
+};
+
+static void *netdev_init(int argc, char *argv[]) {
+  // parse header from /proc/net/dev and prepare metric names
+
+  FILE *f = fopen(PATH("/proc/net/dev"), "r");
+  if (!f) {
+    perror("fopen /proc/net/dev");
+    return 0;
+  }
+
+  char buf[BUF_SIZE];
+  char *p;
+
+  fgets_line(buf, sizeof buf, f);
+  p = fgets_line(buf, sizeof buf, f);
+  fclose(f);
+  if (!p) {
+    fprintf(stderr, "second header line in /proc/net/dev missing\n");
+    return 0;
+  }
+
+  static const char *const prefixes[2] = { "node_network_receive_", "node_network_transmit_" };
+  char *parts[2];
+  char *saveptr;
+
+  strtok_r(buf, "|", &saveptr);
+  parts[0] = strtok_r(0, "|", &saveptr);
+  parts[1] = strtok_r(0, "|", &saveptr);
+  p = strtok_r(0, "|", &saveptr);
+  if (!parts[0] || !parts[1] || p) {
+    fprintf(stderr, "too %s parts in /proc/net/dev header\n", p ? "many" : "few");
+    return 0;
+  }
+
+  struct netdev_context *ctx = malloc(sizeof *ctx);
+  if (!ctx) {
+    perror("malloc");
+    return 0;
+  }
+
+  ctx->ncolumns = 0;
+  for (int part = 0; part < 2; part++) {
+    size_t prefix_len = strlen(prefixes[part]);
+
+    for (p = strtok_r(parts[part], " \n", &saveptr); p; p = strtok_r(0, " \n", &saveptr)) {
+      if (ctx->ncolumns >= MAX_COLUMNS) {
+        fprintf(stderr, "too many columns in /proc/net/dev\n");
+        goto cleanup;
+      }
+
+      size_t header_len = strlen(p);
+      size_t metric_len = prefix_len + header_len + 6;  // 6 for "_total"
+
+      ctx->columns[ctx->ncolumns] = malloc(metric_len + 1);
+      if (!ctx->columns[ctx->ncolumns]) {
+        perror("malloc");
+        goto cleanup;
+      }
+
+      snprintf(ctx->columns[ctx->ncolumns], metric_len + 1, "%s%s_total", prefixes[part], p);
+      ctx->ncolumns++;
+    }
+  }
+
+  // parse command-line arguments
+
+  ctx->include = 0;
+  ctx->exclude = 0;
+  bool exclude_set = false;
+
+  for (int arg = 0; arg < argc; arg++) {
+    if (strncmp(argv[arg], "include=", 8) == 0) {
+      ctx->include = slist_split(argv[arg] + 8, ",");
+      continue;
+    }
+    if (strncmp(argv[arg], "exclude=", 8) == 0) {
+      ctx->exclude = slist_split(argv[arg] + 8, ",");
+      continue;
+    }
+
+    fprintf(stderr, "unknown argument for netdev collector: %s\n", argv[arg]);
+    goto cleanup;
+  }
+
+  if (!exclude_set)
+    ctx->exclude = slist_split(DEFAULT_EXCLUDE, ",");
+
+  return ctx;
+
+cleanup:
+  for (size_t i = 0; i < ctx->ncolumns; i++)
+    free(ctx->columns[i]);
+  free(ctx);
+  return 0;
+}
+
+static void netdev_collect(scrape_req *req, void *ctx_ptr) {
+  struct netdev_context *ctx = ctx_ptr;
+
+  // buffers
+
+  struct label labels[] = {
+    { .key = "device", .value = 0 },  // value filled by code
+    LABEL_END,
+  };
+
+  char buf[BUF_SIZE];
+
+  FILE *f;
+
+  // read network stats from /proc/net/dev
+
+  f = fopen(PATH("/proc/net/dev"), "r");
+  if (!f)
+    return;
+
+  fgets_line(buf, sizeof buf, f);
+  fgets_line(buf, sizeof buf, f);  // skipped header
+
+  while (fgets_line(buf, sizeof buf, f)) {
+    char *dev = buf;
+    while (*dev == ' ')
+      dev++;
+
+    char *p = strchr(dev, ':');
+    if (!p)
+      continue;
+    *p = '\0';
+    labels[0].value = dev;
+    p++;
+
+    if (ctx->include) {
+      if (!slist_matches(ctx->include, dev))
+        continue;
+    } else if (ctx->exclude) {
+      if (slist_matches(ctx->exclude, dev))
+        continue;
+    }
+
+    char *saveptr;
+    p = strtok_r(p, " \n", &saveptr);
+    for (size_t i = 0; i < ctx->ncolumns && p; i++, p = strtok_r(0, " \n", &saveptr)) {
+      char *endptr;
+      double value = strtod(p, &endptr);
+      if (*endptr != '\0')
+        continue;
+      scrape_write(req, ctx->columns[i], labels, value);
+    }
+  }
+
+  fclose(f);
+}