Example of how to interpose yourself in a message stream.

chrome/tools/ipclist/ipcfuzz.cc

+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include <algorithm>
+#include <iostream>
+#include <set>
+#include <vector>
+
+#include "base/command_line.h"
+#include "base/hash_tables.h"
+#include "base/memory/singleton.h"
+#include "base/message_loop.h"
+#include "base/process_util.h"
+#include "base/scoped_ptr.h"
+#include "base/string_number_conversions.h"
+#include "base/string_util.h"
+#include "base/threading/thread.h"
+#include "base/time.h"
+#include "base/utf_string_conversions.h"
+#include "chrome/tools/ipclist/all_messages.h"
+#include "ipc/ipc_message.h"
+#include "ipc/ipc_message_utils.h"
+#include "ipc/ipc_switches.h"
+#include "ipc/ipc_sync_channel.h"
+#include "ipc/ipc_sync_message.h"
+
+#if defined(OS_POSIX)
+#include <unistd.h>
+#endif
+
+namespace IPC {
+class Message;
+
+// Interface implemented by those who select messages for fuzzing.
+class Selector {
+ public:
+  virtual bool FuzzThisMessage(const IPC::Message *msg) = 0;
+};
+
+// Interface implemented by those who fuzz basic types.  The types all
+// correspond to the types which a pickle from base/pickle.h can pickle,
+// plus the floating point types.
+class Fuzzer {
+ public:
+  virtual void FuzzBool(bool* value) = 0;
+  virtual void FuzzInt(int* value) = 0;
+  virtual void FuzzLong(long* value) = 0;
+  virtual void FuzzSize(size_t* value) = 0;
+  virtual void FuzzUChar(unsigned char *value) = 0;
+  virtual void FuzzUInt16(uint16* value) = 0;
+  virtual void FuzzUInt32(uint32* value) = 0;
+  virtual void FuzzInt64(int64* value) = 0;
+  virtual void FuzzUInt64(uint64* value) = 0;
+  virtual void FuzzFloat(float *value) = 0;
+  virtual void FuzzDouble(double *value) = 0;
+  virtual void FuzzString(std::string* value) = 0;
+  virtual void FuzzWString(std::wstring* value) = 0;
+  virtual void FuzzString16(string16* value) = 0;
+  virtual void FuzzData(char* data, int length) = 0;
+  virtual void FuzzBytes(void* data, int data_len) = 0;
+};
+
+}  // Namespace IPC
+
+namespace {
+
+template <typename T>
+void FuzzIntegralType(T* value, unsigned int frequency) {
+  if (rand() % frequency == 0) {
+    switch (rand() % 4) {
+      case 0: (*value) = 0; break;
+      case 1: (*value)--; break;
+      case 2: (*value)++; break;
+      case 3: (*value) ^= rand(); break;
+    }
+  }
+}
+
+template <typename T>
+void FuzzStringType(T* value, unsigned int frequency,
+                    const T& literal1, const T& literal2) {
+  if (rand() % frequency == 0) {
+    switch (rand() % 5) {
+      case 4: (*value) = (*value) + (*value);   // FALLTHROUGH
+      case 3: (*value) = (*value) + (*value);   // FALLTHROUGH
+      case 2: (*value) = (*value) + (*value); break;
+      case 1: (*value) += literal1; break;
+      case 0: (*value) = literal2; break;
+    }
+  }
+}
+
+}  // Namespace
+
+// One such fuzzer implementation.
+class DefaultFuzzer : public IPC::Fuzzer, public IPC::Selector {
+ public:
+  static const int DEFAULT_FREQUENCY = 23;
+
+  DefaultFuzzer() : frequency_(DEFAULT_FREQUENCY) {
+    const char *env_var;
+    if ((env_var = getenv("CHROME_IPC_FUZZING_LIST"))) {
+      std::string str = std::string(env_var);
+      size_t pos;
+      while ((pos = str.find_first_of(',')) != std::string::npos) {
+        message_set_.insert(atoi(str.substr(0, pos).c_str()));
+        str = str.substr(pos+1);
+      }
+      message_set_.insert(atoi(str.c_str()));
+    }
+
+    if ((env_var = getenv("CHROME_IPC_FUZZING_SEED"))) {
+      int new_seed = atoi(env_var);
+      if (new_seed)
+        srand(new_seed);
+    }
+
+    if ((env_var = getenv("CHROME_IPC_FUZZING_FREQUENCY")))
+    {
+      unsigned int new_frequency = atoi(env_var);
+      if (new_frequency)
+        frequency_ = new_frequency;
+    }
+  }
+
+  virtual ~DefaultFuzzer() {}
+
+  // Interface "fuzzer" methods.
+  virtual void FuzzBool(bool* value) {
+    if (rand() % frequency_ == 0)
+      (*value) = !(*value);
+  }
+
+  virtual void FuzzInt(int* value) {
+    FuzzIntegralType<int>(value, frequency_);
+  }
+
+  virtual void FuzzLong(long* value) {
+    FuzzIntegralType<long>(value, frequency_);
+  }
+
+  virtual void FuzzSize(size_t* value) {
+    FuzzIntegralType<size_t>(value, frequency_);
+  }
+
+  virtual void FuzzUChar(unsigned char* value) {
+    FuzzIntegralType<unsigned char>(value, frequency_);
+  }
+
+  virtual void FuzzUInt16(uint16* value) {
+    FuzzIntegralType<uint16>(value, frequency_);
+  }
+
+  virtual void FuzzUInt32(uint32* value) {
+    FuzzIntegralType<uint32>(value, frequency_);
+  }
+
+  virtual void FuzzInt64(int64* value) {
+    FuzzIntegralType<int64>(value, frequency_);
+  }
+
+  virtual void FuzzUInt64(uint64* value) {
+    FuzzIntegralType<uint64>(value, frequency_);
+  }
+
+  virtual void FuzzFloat(float* value) {
+    if (rand() % frequency_ == 0)
+      (*value) *= rand() / 1000000.0;
+  }
+
+  virtual void FuzzDouble(double* value) {
+    if (rand() % frequency_ == 0)
+      (*value) *= rand() / 1000000.0;
+  }
+
+  virtual void FuzzString(std::string* value) {
+    FuzzStringType<std::string>(value, frequency_, "BORKED", "");
+  }
+
+  virtual void FuzzWString(std::wstring* value) {
+    FuzzStringType<std::wstring>(value, frequency_, L"BORKED", L"");
+  }
+
+  virtual void FuzzString16(string16* value) {
+    FuzzStringType<string16>(value, frequency_,
+                             WideToUTF16(L"BORKED"),
+                             WideToUTF16(L""));
+  }
+
+  virtual void FuzzData(char* data, int length) {
+    if (rand() % frequency_ == 0) {
+      for (int i = 0; i < length; ++i) {
+        FuzzIntegralType<char>(&data[i], frequency_);
+      }
+    }
+  }
+
+  virtual void FuzzBytes(void* data, int data_len) {
+    FuzzData(static_cast<char*>(data), data_len);
+  }
+
+  // Interface "selector" methods.
+  virtual bool FuzzThisMessage(const IPC::Message *msg) {
+    return (message_set_.empty() ||
+            std::find(message_set_.begin(),
+                      message_set_.end(),
+                      msg->type()) != message_set_.end());
+  }
+
+ private:
+  std::set<int> message_set_;
+  unsigned int frequency_;
+};
+
+// Partially-specialized class that knows how to fuzz a given type.
+template <class P>
+struct FuzzTraits {
+  static void Fuzz(P* p, IPC::Fuzzer *fuzzer) {}
+};
+
+// Template function to invoke partially-specialized class method.
+template <class P>
+static void FuzzParam(P* p, IPC::Fuzzer* fuzzer) {
+  FuzzTraits<P>::Fuzz(p, fuzzer);
+}
+
+// Specializations to fuzz primitive types.
+template <>
+struct FuzzTraits<bool> {
+  static void Fuzz(bool* p, IPC::Fuzzer* fuzzer) {
+    fuzzer->FuzzBool(p);
+  }
+};
+
+template <>
+struct FuzzTraits<int> {
+  static void Fuzz(int* p, IPC::Fuzzer* fuzzer) {
+    fuzzer->FuzzInt(p);
+  }
+};
+
+template <>
+struct FuzzTraits<unsigned int> {
+  static void Fuzz(unsigned int* p, IPC::Fuzzer* fuzzer) {
+    fuzzer->FuzzInt(reinterpret_cast<int*>(p));
+  }
+};
+
+template <>
+struct FuzzTraits<long> {
+  static void Fuzz(long* p, IPC::Fuzzer* fuzzer) {
+    fuzzer->FuzzLong(p);
+  }
+};
+
+template <>
+struct FuzzTraits<unsigned long> {
+  static void Fuzz(unsigned long* p, IPC::Fuzzer* fuzzer) {
+    fuzzer->FuzzLong(reinterpret_cast<long*>(p));
+  }
+};
+
+template <>
+struct FuzzTraits<long long> {
+  static void Fuzz(long long* p, IPC::Fuzzer* fuzzer) {
+    fuzzer->FuzzInt64(reinterpret_cast<int64*>(p));
+  }
+};
+
+template <>
+struct FuzzTraits<unsigned long long> {
+  static void Fuzz(unsigned long long* p, IPC::Fuzzer* fuzzer) {
+    fuzzer->FuzzInt64(reinterpret_cast<int64*>(p));
+  }
+};
+
+template <>
+struct FuzzTraits<short> {
+  static void Fuzz(short* p, IPC::Fuzzer* fuzzer) {
+    fuzzer->FuzzUInt16(reinterpret_cast<uint16*>(p));
+  }
+};
+
+template <>
+struct FuzzTraits<unsigned short> {
+  static void Fuzz(unsigned short* p, IPC::Fuzzer* fuzzer) {
+    fuzzer->FuzzUInt16(reinterpret_cast<uint16*>(p));
+  }
+};
+
+template <>
+struct FuzzTraits<char> {
+  static void Fuzz(char* p, IPC::Fuzzer* fuzzer) {
+    fuzzer->FuzzUChar(reinterpret_cast<unsigned char*>(p));
+  }
+};
+
+template <>
+struct FuzzTraits<unsigned char> {
+  static void Fuzz(unsigned char* p, IPC::Fuzzer* fuzzer) {
+    fuzzer->FuzzUChar(p);
+  }
+};
+
+template <>
+struct FuzzTraits<float> {
+  static void Fuzz(float* p, IPC::Fuzzer* fuzzer) {
+    fuzzer->FuzzFloat(p);
+  }
+};
+
+template <>
+struct FuzzTraits<double> {
+  static void Fuzz(double* p, IPC::Fuzzer* fuzzer) {
+    fuzzer->FuzzDouble(p);
+  }
+};
+
+template <>
+struct FuzzTraits<std::string> {
+  static void Fuzz(std::string* p, IPC::Fuzzer* fuzzer) {
+    fuzzer->FuzzString(p);
+  }
+};
+
+template <>
+struct FuzzTraits<std::wstring> {
+  static void Fuzz(std::wstring* p, IPC::Fuzzer* fuzzer) {
+    fuzzer->FuzzWString(p);
+  }
+};
+
+template <>
+struct FuzzTraits<string16> {
+  static void Fuzz(string16* p, IPC::Fuzzer* fuzzer) {
+    fuzzer->FuzzString16(p);
+  }
+};
+
+// Specializations to fuzz tuples.
+template <class A>
+struct FuzzTraits<Tuple1<A> > {
+  static void Fuzz(Tuple1<A>* p, IPC::Fuzzer* fuzzer) {
+    FuzzParam(&p->a, fuzzer);
+  }
+};
+
+template <class A, class B>
+struct FuzzTraits<Tuple2<A, B> > {
+  static void Fuzz(Tuple2<A, B>* p, IPC::Fuzzer* fuzzer) {
+    FuzzParam(&p->a, fuzzer);
+    FuzzParam(&p->b, fuzzer);
+  }
+};
+
+template <class A, class B, class C>
+struct FuzzTraits<Tuple3<A, B, C> > {
+  static void Fuzz(Tuple3<A, B, C>* p, IPC::Fuzzer* fuzzer) {
+    FuzzParam(&p->a, fuzzer);
+    FuzzParam(&p->b, fuzzer);
+    FuzzParam(&p->c, fuzzer);
+  }
+};
+
+template <class A, class B, class C, class D>
+struct FuzzTraits<Tuple4<A, B, C, D> > {
+  static void Fuzz(Tuple4<A, B, C, D>* p, IPC::Fuzzer* fuzzer) {
+    FuzzParam(&p->a, fuzzer);
+    FuzzParam(&p->b, fuzzer);
+    FuzzParam(&p->c, fuzzer);
+    FuzzParam(&p->d, fuzzer);
+  }
+};
+
+template <class A, class B, class C, class D, class E>
+struct FuzzTraits<Tuple5<A, B, C, D, E> > {
+  static void Fuzz(Tuple5<A, B, C, D, E>* p, IPC::Fuzzer* fuzzer) {
+    FuzzParam(&p->a, fuzzer);
+    FuzzParam(&p->b, fuzzer);
+    FuzzParam(&p->c, fuzzer);
+    FuzzParam(&p->d, fuzzer);
+    FuzzParam(&p->e, fuzzer);
+  }
+};
+
+// Specializations to fuzz containers.
+template <class A>
+struct FuzzTraits<std::vector<A> > {
+  static void Fuzz(std::vector<A>* p, IPC::Fuzzer* fuzzer) {
+    for (size_t i = 0; i < p->size(); ++i) {
+      FuzzParam(&p->at(i), fuzzer);
+    }
+  }
+};
+
+template <class A, class B>
+struct FuzzTraits<std::map<A, B> > {
+  static void Fuzz(std::map<A, B>* p, IPC::Fuzzer* fuzzer) {
+    typename std::map<A, B>::iterator it;
+    for (it = p->begin(); it != p->end(); ++it) {
+      FuzzParam(&it->second, fuzzer);
+    }
+  }
+};
+
+template <class A, class B>
+struct FuzzTraits<std::pair<A, B> > {
+  static void Fuzz(std::pair<A, B>* p, IPC::Fuzzer* fuzzer) {
+    FuzzParam(&p->second, fuzzer);
+  }
+};
+
+// Specializations to fuzz hand-coded tyoes
+template <>
+struct FuzzTraits<base::FileDescriptor> {
+  static void Fuzz(base::FileDescriptor* p, IPC::Fuzzer* fuzzer) {
+    FuzzParam(&p->fd, fuzzer);
+  }
+};
+
+template <>
+struct FuzzTraits<GURL> {
+  static void Fuzz(GURL *p, IPC::Fuzzer* fuzzer) {
+    FuzzParam(&p->possibly_invalid_spec(), fuzzer);
+  }
+};
+
+template <>
+struct FuzzTraits<gfx::Point> {
+  static void Fuzz(gfx::Point *p, IPC::Fuzzer* fuzzer) {
+    int x = p->x();
+    int y = p->y();
+    FuzzParam(&x, fuzzer);
+    FuzzParam(&y, fuzzer);
+    p->SetPoint(x, y);
+  }
+};
+
+template <>
+struct FuzzTraits<gfx::Size> {
+  static void Fuzz(gfx::Size *p, IPC::Fuzzer* fuzzer) {
+    int w = p->width();
+    int h = p->height();
+    FuzzParam(&w, fuzzer);
+    FuzzParam(&h, fuzzer);
+    p->SetSize(w, h);
+  }
+};
+
+template <>
+struct FuzzTraits<gfx::Rect> {
+  static void Fuzz(gfx::Rect *p, IPC::Fuzzer* fuzzer) {
+    gfx::Point origin = p->origin();
+    gfx::Size  size = p->size();
+    FuzzParam(&origin, fuzzer);
+    FuzzParam(&size, fuzzer);
+    p->set_origin(origin);
+    p->set_size(size);
+  }
+};
+
+// Redefine macros to generate fuzzing from traits declarations.
+// Null out all the macros that need nulling.
+#include "ipc/ipc_message_null_macros.h"
+
+// STRUCT declarations cause corresponding STRUCT_TRAITS declarations to occur.
+#undef IPC_STRUCT_BEGIN
+#undef IPC_STRUCT_MEMBER
+#undef IPC_STRUCT_END
+#define IPC_STRUCT_BEGIN(struct_name) IPC_STRUCT_TRAITS_BEGIN(struct_name)
+#define IPC_STRUCT_MEMBER(type, name) IPC_STRUCT_TRAITS_MEMBER(name)
+#define IPC_STRUCT_END() IPC_STRUCT_TRAITS_END()
+
+// Set up so next include will generate fuzz trait classes.
+#undef IPC_STRUCT_TRAITS_BEGIN
+#undef IPC_STRUCT_TRAITS_MEMBER
+#undef IPC_STRUCT_TRAITS_PARENT
+#undef IPC_STRUCT_TRAITS_END
+#define IPC_STRUCT_TRAITS_BEGIN(struct_name) \
+  template <> \
+  struct FuzzTraits<struct_name> { \
+    static void Fuzz(struct_name *p, IPC::Fuzzer* fuzzer) { \
+
+#define IPC_STRUCT_TRAITS_MEMBER(name) \
+      FuzzParam(&p->name, fuzzer);
+
+#define IPC_STRUCT_TRAITS_PARENT(type) \
+      FuzzParam(static_cast<type*>(p), fuzzer);
+
+#define IPC_STRUCT_TRAITS_END() \
+    } \
+  };
+
+#undef IPC_ENUM_TRAITS
+#define IPC_ENUM_TRAITS(enum_name) \
+  template <> \
+  struct FuzzTraits<enum_name> { \
+    static void Fuzz(enum_name* p, IPC::Fuzzer* fuzzer) { \
+      FuzzParam(reinterpret_cast<int*>(p), fuzzer); \
+    } \
+  };
+
+// Bring them into existence.
+#include "chrome/tools/ipclist/all_messages.h"
+
+// Redefine macros to generate fuzzing funtions
+#include "ipc/ipc_message_null_macros.h"
+#undef IPC_MESSAGE_DECL
+#define IPC_MESSAGE_DECL(kind, type, name, in, out, ilist, olist)           \
+  IPC_##kind##_##type##_FUZZ(name, in, out, ilist, olist)
+
+#define IPC_EMPTY_CONTROL_FUZZ(name, in, out, ilist, olist)                 \
+  IPC::Message* fuzzer_for_##name(IPC::Message *msg, IPC::Fuzzer* fuzzer) { \
+    return NULL;                                                            \
+  }
+
+#define IPC_EMPTY_ROUTED_FUZZ(name, in, out, ilist, olist)                  \
+  IPC::Message* fuzzer_for_##name(IPC::Message *msg, IPC::Fuzzer* fuzzer) { \
+    return NULL;                                                            \
+  }
+
+#define IPC_ASYNC_CONTROL_FUZZ(name, in, out, ilist, olist)                 \
+  IPC::Message* fuzzer_for_##name(IPC::Message *msg, IPC::Fuzzer* fuzzer) { \
+    name* real_msg = static_cast<name*>(msg);                               \
+    IPC_TUPLE_IN_##in ilist p;                                              \
+    name::Read(real_msg, &p);                                               \
+    FuzzParam(&p, fuzzer);                                                  \
+    return new name(IPC_MEMBERS_IN_##in(p));                                \
+  }
+
+#define IPC_ASYNC_ROUTED_FUZZ(name, in, out, ilist, olist)                  \
+  IPC::Message* fuzzer_for_##name(IPC::Message *msg, IPC::Fuzzer* fuzzer) { \
+    name* real_msg = static_cast<name*>(msg);                               \
+    IPC_TUPLE_IN_##in ilist p;                                              \
+    name::Read(real_msg, &p);                                               \
+    FuzzParam(&p, fuzzer);                                                  \
+    return new name(msg->routing_id()                                       \
+                    IPC_COMMA_##in                                          \
+                    IPC_MEMBERS_IN_##in(p));                                \
+  }
+
+#define IPC_SYNC_CONTROL_FUZZ(name, in, out, ilist, olist)                  \
+  IPC::Message* fuzzer_for_##name(IPC::Message *msg, IPC::Fuzzer* fuzzer) { \
+    name* real_msg = static_cast<name*>(msg);                               \
+    IPC_TUPLE_IN_##in ilist p;                                              \
+    name::ReadSendParam(real_msg, &p);                                      \
+    FuzzParam(&p, fuzzer);                                                  \
+    IPC_TUPLE_OUT_##out olist q =                                           \
+        static_cast<IPC::ParamDeserializer<IPC_TUPLE_OUT_##out olist>*>(    \
+            real_msg->GetReplyDeserializer())->out_;                        \
+    name* new_msg = new name(IPC_MEMBERS_IN_##in(p)                         \
+                             IPC_COMMA_AND_##out(IPC_COMMA_##in)            \
+                             IPC_MEMBERS_OUT_##out(q));                     \
+    return new_msg;                                                         \
+  }
+
+
+#define IPC_SYNC_ROUTED_FUZZ(name, in, out, ilist, olist)                   \
+  IPC::Message* fuzzer_for_##name(IPC::Message *msg, IPC::Fuzzer* fuzzer) { \
+    name* real_msg = static_cast<name*>(msg);                               \
+    IPC_TUPLE_IN_##in ilist p;                                              \
+    name::ReadSendParam(real_msg, &p);                                      \
+    FuzzParam(&p, fuzzer);                                                  \
+    IPC_TUPLE_OUT_##out olist q =                                           \
+        static_cast<IPC::ParamDeserializer<IPC_TUPLE_OUT_##out olist>*>(    \
+            real_msg->GetReplyDeserializer())->out_;                        \
+    name* new_msg = new name(msg->routing_id()                              \
+                             IPC_COMMA_OR_##out(IPC_COMMA_##in)             \
+                             IPC_MEMBERS_IN_##in(p)                         \
+                             IPC_COMMA_AND_##out(IPC_COMMA_##in)            \
+                             IPC_MEMBERS_OUT_##out(q));                     \
+    return new_msg;                                                         \
+  }
+
+#define IPC_MEMBERS_IN_0(p)
+#define IPC_MEMBERS_IN_1(p)                 p.a
+#define IPC_MEMBERS_IN_2(p)                 p.a, p.b
+#define IPC_MEMBERS_IN_3(p)                 p.a, p.b, p.c
+#define IPC_MEMBERS_IN_4(p)                 p.a, p.b, p.c, p.d
+#define IPC_MEMBERS_IN_5(p)                 p.a, p.b, p.c, p.d, p.e
+
+#define IPC_MEMBERS_OUT_0(q)
+#define IPC_MEMBERS_OUT_1(q)                &q.a
+#define IPC_MEMBERS_OUT_2(q)                &q.a, &q.b
+#define IPC_MEMBERS_OUT_3(q)                &q.a, &q.b, &q.c
+#define IPC_MEMBERS_OUT_4(q)                &q.a, &q.b, &q.c, &q.d
+#define IPC_MEMBERS_OUT_5(q)                &q.a, &q.b, &q.c, &q.d, &q.e
+
+#include "chrome/tools/ipclist/all_messages.h"
+
+typedef IPC::Message* (*FuzzFunction)(IPC::Message*, IPC::Fuzzer*);
+typedef base::hash_map<uint32, FuzzFunction> FuzzFunctionMap;
+
+// Redefine macros to register fuzzing functions into map.
+#include "ipc/ipc_message_null_macros.h"
+#undef IPC_MESSAGE_DECL
+#define IPC_MESSAGE_DECL(kind, type, name, in, out, ilist, olist) \
+  (*map)[static_cast<uint32>(name::ID)] = fuzzer_for_##name;
+
+void PopulateFuzzFunctionMap(FuzzFunctionMap *map) {
+#include "chrome/tools/ipclist/all_messages.h"
+}
+
+class ipcfuzz : public IPC::OutgoingMessageFilter {
+ public:
+  ipcfuzz() : fuzzer_(NULL), selector_(NULL) {
+    PopulateFuzzFunctionMap(&fuzz_function_map_);
+    DefaultFuzzer *fuzzer = new DefaultFuzzer();
+    fuzzer_ = fuzzer;
+    selector_ = fuzzer;
+  }
+
+  IPC::Message* Rewrite(IPC::Message* message) {
+    if (fuzzer_ && selector_ && selector_->FuzzThisMessage(message)) {
+      FuzzFunctionMap::iterator it = fuzz_function_map_.find(message->type());
+      if (it != fuzz_function_map_.end()) {
+        IPC::Message* fuzzed_message = (*it->second)(message, fuzzer_);
+        if (fuzzed_message)  {
+          delete message;
+          message = fuzzed_message;
+        }
+      }
+    }
+    return message;
+  }
+
+ private:
+  IPC::Fuzzer* fuzzer_;
+  IPC::Selector* selector_;
+  FuzzFunctionMap fuzz_function_map_;
+};
+
+ipcfuzz g_ipcfuzz;
+
+// Entry point avoiding mangled names.
+extern "C" {
+  __attribute__((visibility("default")))
+    IPC::OutgoingMessageFilter* GetFilter(void);
+}
+
+IPC::OutgoingMessageFilter* GetFilter(void) {
+  return &g_ipcfuzz;
+}
+