TypedMsgHdr.h
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1/*
2 * Copyright (C) 1996-2022 The Squid Software Foundation and contributors
3 *
4 * Squid software is distributed under GPLv2+ license and includes
5 * contributions from numerous individuals and organizations.
6 * Please see the COPYING and CONTRIBUTORS files for details.
7 */
8
9/* DEBUG: section 54 Interprocess Communication */
10
11#ifndef SQUID_IPC_TYPED_MSG_HDR_H
12#define SQUID_IPC_TYPED_MSG_HDR_H
13
14#include "compat/cmsg.h"
15#include "ipc/Messages.h"
16#if HAVE_SYS_SOCKET_H
17#include <sys/socket.h>
18#endif
19#if HAVE_SYS_UIO_H
20#include <sys/uio.h>
21#endif
22#if HAVE_SYS_UN_H
23#include <sys/un.h>
24#endif
25
26#include <type_traits>
27
28class String;
29
30namespace Ipc
31{
32
34class TypedMsgHdr: public msghdr
35{
36public:
37 enum {maxSize = 4096};
38
39public:
41 TypedMsgHdr(const TypedMsgHdr &tmh);
43
44 void address(const struct sockaddr_un &addr);
45
46 /* message type manipulation; these must be called before put/get*() */
47 void setType(int aType);
48 void checkType(int aType) const;
51 int rawType() const { return msg_iov ? data.type_ : 0; }
52
53 /* access for TriviallyCopyable (a.k.a. Plain Old Data or POD) message parts */
54 template <class Pod> void getPod(Pod &pod) const;
55 template <class Pod> void putPod(const Pod &pod);
56
57 /* access to message parts for selected commonly-used part types */
58 void getString(String &s) const;
59 void putString(const String &s);
60 int getInt() const;
61 void putInt(int n);
62 void getFixed(void *raw, size_t size) const;
63 void putFixed(const void *raw, size_t size);
64
66 bool hasMoreData() const { return offset < data.size; }
67
68 /* access to a "file" descriptor that can be passed between processes */
69 void putFd(int aFd);
70 int getFd() const;
71 bool hasFd() const;
72
73 /* raw, type-independent access for I/O */
74 void prepForReading();
75 char *raw() { return reinterpret_cast<char*>(this); }
76 const char *raw() const { return reinterpret_cast<const char*>(this); }
77 size_t size() const { return sizeof(*this); }
78
79private:
80 void clear();
81 void sync();
82 void allocData();
83 void allocName();
84 void allocControl();
85
86 /* raw, type-independent manipulation used by type-specific methods */
87 void getRaw(void *raw, size_t size) const;
88 void putRaw(const void *raw, size_t size);
89
90private:
92
93 struct iovec ios[1];
94
95 struct DataBuffer {
96 DataBuffer() { memset(raw, 0, sizeof(raw)); }
97
98 int type_ = 0;
99 size_t size = 0;
100 char raw[maxSize];
102
103 struct CtrlBuffer {
104 CtrlBuffer() { memset(raw, 0, sizeof(raw)); }
105
107 char raw[SQUID_CMSG_SPACE(sizeof(int))];
109
111 mutable unsigned int offset = 0;
112};
113
114} // namespace Ipc
115
116template <class Pod>
117void
119{
120#if HAVE_STD_IS_TRIVIALLY_COPYABLE
121 static_assert(std::is_trivially_copyable<Pod>::value, "getPod() used for a POD");
122#endif
123 getFixed(&pod, sizeof(pod));
124}
125
126template <class Pod>
127void
129{
130#if HAVE_STD_IS_TRIVIALLY_COPYABLE
131 static_assert(std::is_trivially_copyable<Pod>::value, "putPod() used for a POD");
132#endif
133 putFixed(&pod, sizeof(pod));
134}
135
136#endif /* SQUID_IPC_TYPED_MSG_HDR_H */
137
struct msghdr with a known type, fixed-size I/O and control buffers
Definition: TypedMsgHdr.h:35
struct Ipc::TypedMsgHdr::CtrlBuffer ctrl
same as .msg_control
void getRaw(void *raw, size_t size) const
low-level loading of exactly size bytes of raw data
Definition: TypedMsgHdr.cc:166
int getFd() const
returns stored descriptor
Definition: TypedMsgHdr.cc:217
unsigned int offset
data offset for the next get/put*() to start with
Definition: TypedMsgHdr.h:111
void putRaw(const void *raw, size_t size)
low-level storage of exactly size bytes of raw data
Definition: TypedMsgHdr.cc:177
void putString(const String &s)
store variable-length string
Definition: TypedMsgHdr.cc:143
TypedMsgHdr & operator=(const TypedMsgHdr &tmh)
Definition: TypedMsgHdr.cc:31
void putFd(int aFd)
stores descriptor
Definition: TypedMsgHdr.cc:196
bool hasMoreData() const
returns true if there is data to extract; handy for optional parts
Definition: TypedMsgHdr.h:66
const char * raw() const
Definition: TypedMsgHdr.h:76
void getFixed(void *raw, size_t size) const
always load size bytes
Definition: TypedMsgHdr.cc:151
struct Ipc::TypedMsgHdr::DataBuffer data
same as .msg_iov[0].iov_base
void putInt(int n)
store an integer
Definition: TypedMsgHdr.cc:119
size_t size() const
not true message size
Definition: TypedMsgHdr.h:77
void getPod(Pod &pod) const
load POD
Definition: TypedMsgHdr.h:118
void getString(String &s) const
load variable-length string
Definition: TypedMsgHdr.cc:125
bool hasFd() const
whether the message has a descriptor stored
Definition: TypedMsgHdr.cc:187
struct iovec ios[1]
same as .msg_iov[]
Definition: TypedMsgHdr.h:93
struct sockaddr_un name
same as .msg_name
Definition: TypedMsgHdr.h:91
void allocData()
initialize io vector with one io record
Definition: TypedMsgHdr.cc:246
void checkType(int aType) const
Definition: TypedMsgHdr.cc:94
void putFixed(const void *raw, size_t size)
always store size bytes
Definition: TypedMsgHdr.cc:158
int rawType() const
Definition: TypedMsgHdr.h:51
void prepForReading()
reset and provide all buffers
Definition: TypedMsgHdr.cc:234
void putPod(const Pod &pod)
store POD
Definition: TypedMsgHdr.h:128
void setType(int aType)
sets message type; use MessageType enum
Definition: TypedMsgHdr.cc:100
int getInt() const
load an integer
Definition: TypedMsgHdr.cc:111
void address(const struct sockaddr_un &addr)
sets [dest.] address
Definition: TypedMsgHdr.cc:85
#define SQUID_CMSG_SPACE
Definition: cmsg.h:136
Definition: IpcIoFile.h:24
char raw[SQUID_CMSG_SPACE(sizeof(int))]
control buffer space for one fd
Definition: TypedMsgHdr.h:107
int type_
Message kind, uses MessageType values.
Definition: TypedMsgHdr.h:98
size_t size
actual raw data size (for sanity checks)
Definition: TypedMsgHdr.h:99
char raw[maxSize]
buffer with type-specific data
Definition: TypedMsgHdr.h:100
Definition: cmsg.h:81
Definition: cmsg.h:88
struct iovec * msg_iov
Definition: cmsg.h:92

 

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