src/ipc/TypedMsgHdr.h

   1 /*
   2  * $Id$
   3  *
   4  * DEBUG: section 54    Interprocess Communication
   5  *
   6  */
   7
   8 #ifndef SQUID_IPC_TYPED_MSG_HDR_H
   9 #define SQUID_IPC_TYPED_MSG_HDR_H
  10
  11 #include "compat/cmsg.h"
  12 #if HAVE_SYS_SOCKET_H
  13 #include <sys/socket.h>
  14 #endif
  15 #if HAVE_SYS_UIO_H
  16 #include <sys/uio.h>
  17 #endif
  18 #if HAVE_SYS_UN_H
  19 #include <sys/un.h>
  20 #endif
  21
  22 class String;
  23
  24 namespace Ipc
  25 {
  26
  27 /// struct msghdr with a known type, fixed-size I/O and control buffers
  28 class TypedMsgHdr: public msghdr
  29 {
  30 public:
  31     enum {maxSize = 4096};
  32
  33 public:
  34     TypedMsgHdr();
  35     TypedMsgHdr(const TypedMsgHdr &tmh);
  36     TypedMsgHdr &operator =(const TypedMsgHdr &tmh);
  37
  38     void address(const struct sockaddr_un &addr); ///< sets [dest.] address
  39
  40     /* message type manipulation; these must be called before put/get*() */
  41     void setType(int aType); ///< sets message type; use MessageType enum
  42     void checkType(int aType) const; ///< throws if stored type is not aType
  43     int type() const; ///< returns stored type or zero if none
  44
  45     /* access for Plain Old Data (POD)-based message parts */
  46     template <class Pod>
  47     void getPod(Pod &pod) const { getFixed(&pod, sizeof(pod)); } ///< load POD
  48     template <class Pod>
  49     void putPod(const Pod &pod) { putFixed(&pod, sizeof(pod)); } ///< store POD
  50
  51     /* access to message parts for selected commonly-used part types */
  52     void getString(String &s) const; ///< load variable-length string
  53     void putString(const String &s); ///< store variable-length string
  54     int getInt() const; ///< load an integer
  55     void putInt(int n); ///< store an integer
  56     void getFixed(void *raw, size_t size) const; ///< always load size bytes
  57     void putFixed(const void *raw, size_t size); ///< always store size bytes
  58
  59     /// returns true if there is data to extract; handy for optional parts
  60     bool hasMoreData() const { return offset < data.size; }
  61
  62     /* access to a "file" descriptor that can be passed between processes */
  63     void putFd(int aFd); ///< stores descriptor
  64     int getFd() const; ///< returns descriptor
  65
  66     /* raw, type-independent access for I/O */
  67     void prepForReading(); ///< reset and provide all buffers
  68     char *raw() { return reinterpret_cast<char*>(this); }
  69     const char *raw() const { return reinterpret_cast<const char*>(this); }
  70     size_t size() const { return sizeof(*this); } ///< not true message size
  71
  72 private:
  73     void sync();
  74     void allocData();
  75     void allocName();
  76     void allocControl();
  77
  78     /* raw, type-independent manipulation used by type-specific methods */
  79     void getRaw(void *raw, size_t size) const;
  80     void putRaw(const void *raw, size_t size);
  81
  82 private:
  83     struct sockaddr_un name; ///< same as .msg_name
  84
  85     struct iovec ios[1]; ///< same as .msg_iov[]
  86
  87     struct DataBuffer {
  88         int type_; ///< Message kind, uses MessageType values
  89         size_t size; ///< actual raw data size (for sanity checks)
  90         char raw[maxSize]; ///< buffer with type-specific data
  91     } data; ///< same as .msg_iov[0].iov_base
  92
  93     struct CtrlBuffer {
  94         /// control buffer space for one fd
  95         char raw[SQUID_CMSG_SPACE(sizeof(int))];
  96     } ctrl; ///< same as .msg_control
  97
  98     /// data offset for the next get/put*() to start with
  99     mutable unsigned int offset;
 100 };
 101
 102 } // namespace Ipc
 103
 104 #endif /* SQUID_IPC_TYPED_MSG_HDR_H */