1 files changed, 109 insertions, 0 deletions
diff --git a/src/plugins/examples/health_check.c b/src/plugins/examples/health_check.c
new file mode 100644
index 00000000000..5f0d85fec08
--- /dev/null
+++ b/src/plugins/examples/health_check.c
@@ -0,0 +1,109 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <netinet/in.h>
+#include <netinet/ip.h>
+#include <netinet/ip_icmp.h>
+#include <arpa/inet.h>
+#include <net/if.h>
+#include <stdbool.h>
+#include <errno.h>
+
+static void
+usage (void) {
+  fprintf(stderr,
+	  "Usage: health_check"
+	  " -d debug"
+	  " -I interface"
+	  "\n");
+  exit(2);
+}
+
+int
+main (int argc, char **argv)
+{
+  int sd, ch;
+  uint8_t *opt, *pkt;
+  struct ifreq ifr;
+  char *interface = NULL;
+  bool debug = false;
+
+  while ((ch = getopt(argc, argv, "h?" "I:" "d")) != EOF) {
+    switch(ch) {
+    case 'I':
+      interface = optarg;
+      break;
+    case 'd':
+      debug = true;
+      break;
+    default:
+      usage();
+      break;
+    }
+  }
+
+  argc -= optind;
+  argv += optind;
+
+  if (!interface)
+    usage();
+
+  /* Request a socket descriptor sd. */
+  if ((sd = socket (AF_INET6, SOCK_RAW, IPPROTO_IPIP)) < 0) {
+    perror ("Failed to get socket descriptor ");
+    exit (EXIT_FAILURE);
+  }
+
+  memset(&ifr, 0, sizeof(ifr));
+  snprintf(ifr.ifr_name, sizeof(ifr.ifr_name), "%s", interface);
+
+  /* Bind socket to interface of this node. */
+  if (setsockopt (sd, SOL_SOCKET, SO_BINDTODEVICE, (void *) &ifr, sizeof (ifr)) < 0) {
+    perror ("SO_BINDTODEVICE failed");
+    exit (EXIT_FAILURE);
+  }
+  if (debug) printf("Binding to interface %s\n", interface);
+
+  while (1) {
+    struct sockaddr_in6 src_addr;
+    socklen_t addrlen = sizeof(src_addr);
+    char source[INET6_ADDRSTRLEN+1];
+    int len;
+    uint8_t inpack[IP_MAXPACKET];
+
+    if ((len = recvfrom(sd, inpack, sizeof(inpack), 0, (struct sockaddr *)&src_addr, &addrlen)) < 0) {
+      perror("recvfrom failed ");
+    }
+    if (inet_ntop(AF_INET6, &src_addr.sin6_addr, source, INET6_ADDRSTRLEN) == NULL) {
+      perror("inet_ntop() failed.");
+      exit(EXIT_FAILURE);
+    }
+
+    /* Reply */
+    struct iphdr *ip = (struct iphdr *)inpack;
+    uint32_t saddr;
+    struct icmphdr *icmp;
+
+    saddr = ip->saddr;
+    ip->saddr = ip->daddr;
+    ip->daddr = saddr;
+
+    switch (ip->protocol) {
+    case 1:
+      if (debug) printf ("ICMP Echo request from %s\n", source);
+      icmp = (struct icmphdr *)&ip[1];
+      icmp->type = ICMP_ECHOREPLY;
+      break;
+    default:
+      fprintf(stderr, "Unsupported protocol %d", ip->protocol);
+    }
+    if (len = sendto(sd, inpack, len, 0, (struct sockaddr *)&src_addr, addrlen) < 0) {
+      perror("sendto failed ");
+    }
+  }
+
+  close (sd);
+
+  return (EXIT_SUCCESS);
+}