Remove osx dependency on system() call to get arp information

osquery/tables/networking/darwin/arp.cpp

@@ -1,43 +1,117 @@
 // Copyright 2004-present Facebook. All Rights Reserved.
 
+#include <sys/sysctl.h>
+
+#include <net/if.h>
+#include <net/if_dl.h>
+#include <net/if_types.h>
+#include <net/route.h>
+
+#include <netinet/in.h>
+#include <netinet/if_ether.h>
+
+#include <arpa/inet.h>
+
 #include <stdio.h>
 #include <string.h>
 
 #include "osquery/database.h"
 
+typedef struct {
+  struct rt_msghdr m_rtm;
+  char m_space[512];
+} route_msg;
+
 namespace osquery {
 namespace tables {
 
-QueryData genArp() {
-  Row r;
-  QueryData results;
-  FILE *arp_cmd_output;
-  char *line = NULL;
-  size_t length;
-  int ret;
+// Transform the ethernet address in a string
+char * ether_print(u_char *cp)
+{
+  char buf[128];
+  char *copy;
 
-  char ip[32];
-  char mac[64];
-  char iface[32];
+  sprintf(buf, "%02x:%02x:%02x:%02x:%02x:%02x",
+	  cp[0], cp[1], cp[2], cp[3], cp[4], cp[5]);
 
-  // We are already calling 'popen', let's give it some more work with sed to clean.
-  arp_cmd_output = popen("arp -an | sed 's,^[^(]*(\\([^)]*\\)) at \\([^ ]*\\).*on \\([^ ]*\\).*$,\\1 \\2 \\3,'", "r");
-  if (arp_cmd_output == NULL) {
-    return results;
+  copy = (char *) malloc(sizeof(char) * (strlen(buf) + 1));
+
+  if (copy != NULL) {
+    strcpy(copy, buf);
+
+    return copy;
+
+  } else {
+    return NULL;
   }
 
-  ret = getline(&line, &length, arp_cmd_output);
-  while (ret > 0) {
-    sscanf(line, "%s %s %s", ip, mac, iface);
+}
 
-    r["ip"] = ip;
-    r["mac"] = mac;
-    r["iface"] = iface;
+void add_address(struct rt_msghdr *rtm, QueryData *results)
+{
+  Row r;
+  char *ip_addr;
+  std::string mac_addr;
+  struct hostent *hp;
+  struct sockaddr_inarp *sin;
+  struct sockaddr_dl *sdl;
 
-    results.push_back(r);
+  sin = (struct sockaddr_inarp *)(rtm + 1);
+  sdl = (struct sockaddr_dl *)(sin + 1);
 
-    line = NULL;
-    ret = getline(&line, &length, arp_cmd_output);
+  ip_addr = inet_ntoa(sin->sin_addr);
+
+  if (sdl->sdl_alen != 0) {
+    mac_addr = ether_print((u_char *)LLADDR(sdl));
+  } else {
+    mac_addr = "incomplete";
+  }
+  if (rtm->rtm_rmx.rmx_expire == 0) {
+    mac_addr = "permanent";
+  }
+  if (rtm->rtm_addrs & RTA_NETMASK) {
+    sin = (struct sockaddr_inarp *) (sdl->sdl_len + (char *)sdl);
+
+    if (sin->sin_addr.s_addr == 0xffffffff)
+      mac_addr = "published";
+
+    if (sin->sin_len != 8)
+      mac_addr = "weird";
+  }
+
+  r["ip"] = ip_addr;
+  r["mac"] = mac_addr;
+
+  results->push_back(r);
+}
+
+QueryData genArp() {
+  QueryData results;
+
+  int mib[6];
+  size_t needed;
+  char *lim, *buf, *next;
+  struct rt_msghdr *rtm;
+  int found_entry = 0;
+
+  mib[0] = CTL_NET;
+  mib[1] = PF_ROUTE;
+  mib[2] = 0;
+  mib[3] = AF_INET;
+  mib[4] = NET_RT_FLAGS;
+  mib[5] = RTF_LLINFO;
+
+  sysctl(mib, 6, NULL, &needed, NULL, 0) ;
+  buf = (char *) malloc(needed);
+
+  if (sysctl(mib, 6, buf, &needed, NULL, 0) < 0) {
+    free(buf);
+  }
+
+  lim = buf + needed;
+  for (next = buf; next < lim; next += rtm->rtm_msglen) {
+    rtm = (struct rt_msghdr *)(void *)next;
+    add_address(rtm, &results);
   }
 
   return results;

osquery/tables/specs/darwin/arp.table

@@ -0,0 +1,6 @@
+table_name("arp")
+schema([
+    Column(name="ip", type="std::string"),
+    Column(name="mac", type="std::string"),
+])
+implementation("arp@genArp")