Fuzzers for a couple libnetutil functions

fuzz/.gitignore

@@ -0,0 +1,5 @@
+fuzz_PacketParser
+fuzz_dns_packet_parseFromBuffer
+fuzz_ippackethdrinfo
+fuzz_traceroute_decode_reply
+corpus/

fuzz/fuzz_PacketParser.cc

@@ -0,0 +1,19 @@
+#include "common.h"
+#include "../libnetutil/PacketParser.h"
+
+#include <stddef.h>
+#include <stdint.h>
+
+extern "C"
+int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
+{
+  fuzz_init();
+
+  PacketParser pp;
+  PacketElement *pe = NULL;
+  pe = pp.split(data, size);
+
+  pp.test_packet_parser(pe);
+  pp.freePacketChain(pe);
+  return 0;
+}

fuzz/fuzz_ippackethdrinfo.cc

@@ -0,0 +1,27 @@
+#include "common.h"
+#include "../libnetutil/netutil.h"
+
+#include <stddef.h>
+#include <stdint.h>
+
+extern "C"
+int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
+{
+  fuzz_init();
+
+  const int levels[] = {
+    LOW_DETAIL,
+    MEDIUM_DETAIL,
+    HIGH_DETAIL
+  };
+  const char *buf = NULL;
+  static volatile size_t len = 0;
+  for (int i = 0; i < sizeof(levels)/sizeof(levels[0]); i++) {
+    buf = ippackethdrinfo(data, size, levels[i]);
+    len = strlen(buf);
+    if (strncmp(buf, "BOGUS", 5) == 0)
+      return -1;
+  }
+
+  return 0;
+}