1/*
2 Copyright (c) 2007-2016 Contributors as noted in the AUTHORS file
3
4 This file is part of libzmq, the ZeroMQ core engine in C++.
5
6 libzmq is free software; you can redistribute it and/or modify it under
7 the terms of the GNU Lesser General Public License (LGPL) as published
8 by the Free Software Foundation; either version 3 of the License, or
9 (at your option) any later version.
10
11 As a special exception, the Contributors give you permission to link
12 this library with independent modules to produce an executable,
13 regardless of the license terms of these independent modules, and to
14 copy and distribute the resulting executable under terms of your choice,
15 provided that you also meet, for each linked independent module, the
16 terms and conditions of the license of that module. An independent
17 module is a module which is not derived from or based on this library.
18 If you modify this library, you must extend this exception to your
19 version of the library.
20
21 libzmq is distributed in the hope that it will be useful, but WITHOUT
22 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
23 FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
24 License for more details.
25
26 You should have received a copy of the GNU Lesser General Public License
27 along with this program. If not, see <http://www.gnu.org/licenses/>.
28*/
29
30#include "precompiled.hpp"
31#include <stdlib.h>
32#include <string.h>
33#include <cmath>
34
35#include "v2_protocol.hpp"
36#include "v2_decoder.hpp"
37#include "likely.hpp"
38#include "wire.hpp"
39#include "err.hpp"
40
41zmq::v2_decoder_t::v2_decoder_t (size_t bufsize_,
42 int64_t maxmsgsize_,
43 bool zero_copy_) :
44 decoder_base_t<v2_decoder_t, shared_message_memory_allocator> (bufsize_),
45 _msg_flags (0),
46 _zero_copy (zero_copy_),
47 _max_msg_size (maxmsgsize_)
48{
49 int rc = _in_progress.init ();
50 errno_assert (rc == 0);
51
52 // At the beginning, read one byte and go to flags_ready state.
53 next_step (_tmpbuf, 1, &v2_decoder_t::flags_ready);
54}
55
56zmq::v2_decoder_t::~v2_decoder_t ()
57{
58 int rc = _in_progress.close ();
59 errno_assert (rc == 0);
60}
61
62int zmq::v2_decoder_t::flags_ready (unsigned char const *)
63{
64 _msg_flags = 0;
65 if (_tmpbuf[0] & v2_protocol_t::more_flag)
66 _msg_flags |= msg_t::more;
67 if (_tmpbuf[0] & v2_protocol_t::command_flag)
68 _msg_flags |= msg_t::command;
69
70 // The payload length is either one or eight bytes,
71 // depending on whether the 'large' bit is set.
72 if (_tmpbuf[0] & v2_protocol_t::large_flag)
73 next_step (_tmpbuf, 8, &v2_decoder_t::eight_byte_size_ready);
74 else
75 next_step (_tmpbuf, 1, &v2_decoder_t::one_byte_size_ready);
76
77 return 0;
78}
79
80int zmq::v2_decoder_t::one_byte_size_ready (unsigned char const *read_from_)
81{
82 return size_ready (_tmpbuf[0], read_from_);
83}
84
85int zmq::v2_decoder_t::eight_byte_size_ready (unsigned char const *read_from_)
86{
87 // The payload size is encoded as 64-bit unsigned integer.
88 // The most significant byte comes first.
89 const uint64_t msg_size = get_uint64 (_tmpbuf);
90
91 return size_ready (msg_size, read_from_);
92}
93
94int zmq::v2_decoder_t::size_ready (uint64_t msg_size_,
95 unsigned char const *read_pos_)
96{
97 // Message size must not exceed the maximum allowed size.
98 if (_max_msg_size >= 0)
99 if (unlikely (msg_size_ > static_cast<uint64_t> (_max_msg_size))) {
100 errno = EMSGSIZE;
101 return -1;
102 }
103
104 // Message size must fit into size_t data type.
105 if (unlikely (msg_size_ != static_cast<size_t> (msg_size_))) {
106 errno = EMSGSIZE;
107 return -1;
108 }
109
110 int rc = _in_progress.close ();
111 assert (rc == 0);
112
113 // the current message can exceed the current buffer. We have to copy the buffer
114 // data into a new message and complete it in the next receive.
115
116 shared_message_memory_allocator &allocator = get_allocator ();
117 if (unlikely (!_zero_copy
118 || msg_size_ > (size_t) (allocator.data () + allocator.size ()
119 - read_pos_))) {
120 // a new message has started, but the size would exceed the pre-allocated arena
121 // this happens every time when a message does not fit completely into the buffer
122 rc = _in_progress.init_size (static_cast<size_t> (msg_size_));
123 } else {
124 // construct message using n bytes from the buffer as storage
125 // increase buffer ref count
126 // if the message will be a large message, pass a valid refcnt memory location as well
127 rc =
128 _in_progress.init (const_cast<unsigned char *> (read_pos_),
129 static_cast<size_t> (msg_size_),
130 shared_message_memory_allocator::call_dec_ref,
131 allocator.buffer (), allocator.provide_content ());
132
133 // For small messages, data has been copied and refcount does not have to be increased
134 if (_in_progress.is_zcmsg ()) {
135 allocator.advance_content ();
136 allocator.inc_ref ();
137 }
138 }
139
140 if (unlikely (rc)) {
141 errno_assert (errno == ENOMEM);
142 rc = _in_progress.init ();
143 errno_assert (rc == 0);
144 errno = ENOMEM;
145 return -1;
146 }
147
148 _in_progress.set_flags (_msg_flags);
149 // this sets read_pos to
150 // the message data address if the data needs to be copied
151 // for small message / messages exceeding the current buffer
152 // or
153 // to the current start address in the buffer because the message
154 // was constructed to use n bytes from the address passed as argument
155 next_step (_in_progress.data (), _in_progress.size (),
156 &v2_decoder_t::message_ready);
157
158 return 0;
159}
160
161int zmq::v2_decoder_t::message_ready (unsigned char const *)
162{
163 // Message is completely read. Signal this to the caller
164 // and prepare to decode next message.
165 next_step (_tmpbuf, 1, &v2_decoder_t::flags_ready);
166 return 1;
167}
168