src/ipc/TypedMsgHdr.h

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