base/posix/unix_domain_socket_linux.h

   1 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef BASE_POSIX_UNIX_DOMAIN_SOCKET_LINUX_H_
   6 #define BASE_POSIX_UNIX_DOMAIN_SOCKET_LINUX_H_
   7
   8 #include <stdint.h>
   9 #include <sys/types.h>
  10 #include <vector>
  11
  12 #include "base/base_export.h"
  13 #include "base/files/scoped_file.h"
  14 #include "base/memory/scoped_vector.h"
  15 #include "base/process/process_handle.h"
  16
  17 class Pickle;
  18
  19 class BASE_EXPORT UnixDomainSocket {
  20  public:
  21   // Maximum number of file descriptors that can be read by RecvMsg().
  22   static const size_t kMaxFileDescriptors;
  23
  24   // Use to enable receiving process IDs in RecvMsgWithPid.  Should be called on
  25   // the receiving socket (i.e., the socket passed to RecvMsgWithPid). Returns
  26   // true if successful.
  27   static bool EnableReceiveProcessId(int fd);
  28
  29   // Use sendmsg to write the given msg and include a vector of file
  30   // descriptors. Returns true if successful.
  31   static bool SendMsg(int fd,
  32                       const void* msg,
  33                       size_t length,
  34                       const std::vector<int>& fds);
  35
  36   // Use recvmsg to read a message and an array of file descriptors. Returns
  37   // -1 on failure. Note: will read, at most, |kMaxFileDescriptors| descriptors.
  38   static ssize_t RecvMsg(int fd,
  39                          void* msg,
  40                          size_t length,
  41                          ScopedVector<base::ScopedFD>* fds);
  42
  43   // Same as RecvMsg above, but also returns the sender's process ID (as seen
  44   // from the caller's namespace).  However, before using this function to
  45   // receive process IDs, EnableReceiveProcessId() should be called on the
  46   // receiving socket.
  47   static ssize_t RecvMsgWithPid(int fd,
  48                                 void* msg,
  49                                 size_t length,
  50                                 ScopedVector<base::ScopedFD>* fds,
  51                                 base::ProcessId* pid);
  52
  53   // Perform a sendmsg/recvmsg pair.
  54   //   1. This process creates a UNIX SEQPACKET socketpair. Using
  55   //      connection-oriented sockets (SEQPACKET or STREAM) is critical here,
  56   //      because if one of the ends closes the other one must be notified.
  57   //   2. This process writes a request to |fd| with an SCM_RIGHTS control
  58   //      message containing on end of the fresh socket pair.
  59   //   3. This process blocks reading from the other end of the fresh
  60   //      socketpair.
  61   //   4. The target process receives the request, processes it and writes the
  62   //      reply to the end of the socketpair contained in the request.
  63   //   5. This process wakes up and continues.
  64   //
  65   //   fd: descriptor to send the request on
  66   //   reply: buffer for the reply
  67   //   reply_len: size of |reply|
  68   //   result_fd: (may be NULL) the file descriptor returned in the reply
  69   //              (if any)
  70   //   request: the bytes to send in the request
  71   static ssize_t SendRecvMsg(int fd,
  72                              uint8_t* reply,
  73                              unsigned reply_len,
  74                              int* result_fd,
  75                              const Pickle& request);
  76
  77   // Similar to SendRecvMsg(), but |recvmsg_flags| allows to control the flags
  78   // of the recvmsg(2) call.
  79   static ssize_t SendRecvMsgWithFlags(int fd,
  80                                       uint8_t* reply,
  81                                       unsigned reply_len,
  82                                       int recvmsg_flags,
  83                                       int* result_fd,
  84                                       const Pickle& request);
  85  private:
  86   // Similar to RecvMsg, but allows to specify |flags| for recvmsg(2).
  87   static ssize_t RecvMsgWithFlags(int fd,
  88                                   void* msg,
  89                                   size_t length,
  90                                   int flags,
  91                                   ScopedVector<base::ScopedFD>* fds,
  92                                   base::ProcessId* pid);
  93 };
  94
  95 #endif  // BASE_POSIX_UNIX_DOMAIN_SOCKET_LINUX_H_