1 /*
2 * Copyright (c) 2022, The OpenThread Authors.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 * 3. Neither the name of the copyright holder nor the
13 * names of its contributors may be used to endorse or promote products
14 * derived from this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
17 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
20 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
26 * POSSIBILITY OF SUCH DAMAGE.
27 */
28
29 /**
30 * @file
31 * This file implements TCP/IPv6 socket extensions.
32 */
33
34 #include "openthread-core-config.h"
35
36 #if OPENTHREAD_CONFIG_TCP_ENABLE
37
38 #include "tcp6_ext.hpp"
39
40 #include "common/code_utils.hpp"
41 #include "common/error.hpp"
42 #include "common/locator_getters.hpp"
43 #include "common/log.hpp"
44
45 namespace ot {
46 namespace Ip6 {
47
48 RegisterLogModule("TcpExt");
49
Initialize(void * aDataBuffer,size_t aCapacity)50 void TcpCircularSendBuffer::Initialize(void *aDataBuffer, size_t aCapacity)
51 {
52 mDataBuffer = static_cast<uint8_t *>(aDataBuffer);
53 mCapacity = aCapacity;
54 ForceDiscardAll();
55 }
56
Write(Tcp::Endpoint & aEndpoint,const void * aData,size_t aLength,size_t & aWritten,uint32_t aFlags)57 Error TcpCircularSendBuffer::Write(Tcp::Endpoint &aEndpoint,
58 const void *aData,
59 size_t aLength,
60 size_t &aWritten,
61 uint32_t aFlags)
62 {
63 Error error = kErrorNone;
64 size_t bytesFree = GetFreeSpace();
65 size_t writeIndex;
66 uint32_t flags = 0;
67 size_t bytesUntilWrap;
68
69 /*
70 * Handle the case where we don't have enough space to accommodate all of the
71 * provided data.
72 */
73 aLength = Min(aLength, bytesFree);
74 VerifyOrExit(aLength != 0);
75
76 /*
77 * This is a "simplifying" if statement the removes an edge case from the logic
78 * below. It guarantees that a write to an empty buffer will never wrap.
79 */
80 if (mCapacityUsed == 0)
81 {
82 mStartIndex = 0;
83 }
84
85 writeIndex = GetIndex(mStartIndex, mCapacityUsed);
86
87 if ((aFlags & OT_TCP_CIRCULAR_SEND_BUFFER_WRITE_MORE_TO_COME) != 0 && aLength < bytesFree)
88 {
89 flags |= OT_TCP_SEND_MORE_TO_COME;
90 }
91
92 bytesUntilWrap = mCapacity - writeIndex;
93 if (aLength <= bytesUntilWrap)
94 {
95 memcpy(&mDataBuffer[writeIndex], aData, aLength);
96 if (writeIndex == 0)
97 {
98 /*
99 * mCapacityUsed == 0 corresponds to the case where we're writing
100 * to an empty buffer. mCapacityUsed != 0 && writeIndex == 0
101 * corresponds to the case where the buffer is not empty and this is
102 * writing the first bytes that wrap.
103 */
104 uint8_t linkIndex;
105 if (mCapacityUsed == 0)
106 {
107 linkIndex = mFirstSendLinkIndex;
108 }
109 else
110 {
111 linkIndex = 1 - mFirstSendLinkIndex;
112 }
113 {
114 otLinkedBuffer &dataSendLink = mSendLinks[linkIndex];
115
116 dataSendLink.mNext = nullptr;
117 dataSendLink.mData = &mDataBuffer[writeIndex];
118 dataSendLink.mLength = aLength;
119
120 LogDebg("Appending link %u (points to index %u, length %u)", static_cast<unsigned>(linkIndex),
121 static_cast<unsigned>(writeIndex), static_cast<unsigned>(aLength));
122 error = aEndpoint.SendByReference(dataSendLink, flags);
123 }
124 }
125 else
126 {
127 LogDebg("Extending tail link by length %u", static_cast<unsigned>(aLength));
128 error = aEndpoint.SendByExtension(aLength, flags);
129 }
130 VerifyOrExit(error == kErrorNone, aLength = 0);
131 }
132 else
133 {
134 const uint8_t *dataIndexable = static_cast<const uint8_t *>(aData);
135 size_t bytesWrapped = aLength - bytesUntilWrap;
136
137 memcpy(&mDataBuffer[writeIndex], &dataIndexable[0], bytesUntilWrap);
138 memcpy(&mDataBuffer[0], &dataIndexable[bytesUntilWrap], bytesWrapped);
139
140 /*
141 * Because of the "simplifying" if statement at the top, we don't
142 * have to worry about starting from an empty buffer in this case.
143 */
144 LogDebg("Extending tail link by length %u (wrapping)", static_cast<unsigned>(bytesUntilWrap));
145 error = aEndpoint.SendByExtension(bytesUntilWrap, flags | OT_TCP_SEND_MORE_TO_COME);
146 VerifyOrExit(error == kErrorNone, aLength = 0);
147
148 {
149 otLinkedBuffer &wrappedDataSendLink = mSendLinks[1 - mFirstSendLinkIndex];
150
151 wrappedDataSendLink.mNext = nullptr;
152 wrappedDataSendLink.mData = &mDataBuffer[0];
153 wrappedDataSendLink.mLength = bytesWrapped;
154
155 LogDebg("Appending link %u (wrapping)", static_cast<unsigned>(1 - mFirstSendLinkIndex));
156 error = aEndpoint.SendByReference(wrappedDataSendLink, flags);
157 VerifyOrExit(error == kErrorNone, aLength = bytesUntilWrap);
158 }
159 }
160
161 exit:
162 mCapacityUsed += aLength;
163 aWritten = aLength;
164 return error;
165 }
166
HandleForwardProgress(size_t aInSendBuffer)167 void TcpCircularSendBuffer::HandleForwardProgress(size_t aInSendBuffer)
168 {
169 size_t bytesRemoved;
170 size_t bytesUntilWrap;
171
172 OT_ASSERT(aInSendBuffer <= mCapacityUsed);
173 LogDebg("Forward progress: %u bytes in send buffer\n", static_cast<unsigned>(aInSendBuffer));
174 bytesRemoved = mCapacityUsed - aInSendBuffer;
175 bytesUntilWrap = mCapacity - mStartIndex;
176
177 if (bytesRemoved < bytesUntilWrap)
178 {
179 mStartIndex += bytesRemoved;
180 }
181 else
182 {
183 mStartIndex = bytesRemoved - bytesUntilWrap;
184 /* The otLinkedBuffer for the pre-wrap data is now empty. */
185 LogDebg("Pre-wrap linked buffer now empty: switching first link index from %u to %u\n",
186 static_cast<unsigned>(mFirstSendLinkIndex), static_cast<unsigned>(1 - mFirstSendLinkIndex));
187 mFirstSendLinkIndex = 1 - mFirstSendLinkIndex;
188 }
189 mCapacityUsed = aInSendBuffer;
190 }
191
GetFreeSpace(void) const192 size_t TcpCircularSendBuffer::GetFreeSpace(void) const { return mCapacity - mCapacityUsed; }
193
ForceDiscardAll(void)194 void TcpCircularSendBuffer::ForceDiscardAll(void)
195 {
196 mStartIndex = 0;
197 mCapacityUsed = 0;
198 mFirstSendLinkIndex = 0;
199 }
200
Deinitialize(void)201 Error TcpCircularSendBuffer::Deinitialize(void) { return (mCapacityUsed != 0) ? kErrorBusy : kErrorNone; }
202
GetIndex(size_t aStart,size_t aOffsetFromStart) const203 size_t TcpCircularSendBuffer::GetIndex(size_t aStart, size_t aOffsetFromStart) const
204 {
205 size_t bytesUntilWrap;
206 size_t index;
207
208 OT_ASSERT(aStart < mCapacity);
209 bytesUntilWrap = mCapacity - aStart;
210 if (aOffsetFromStart < bytesUntilWrap)
211 {
212 index = aStart + aOffsetFromStart;
213 }
214 else
215 {
216 index = aOffsetFromStart - bytesUntilWrap;
217 }
218
219 return index;
220 }
221
222 } // namespace Ip6
223 } // namespace ot
224
225 #endif // OPENTHREAD_CONFIG_TCP_ENABLE
226
