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[lowpan] update BufferWriter to use end pointer instead of length (#4453)

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This commit also updates some of `Lowpan` (decompression) methods to
use an end pointer instead of tracking remaining length.
This commit is contained in:
Abtin Keshavarzian
2020-01-13 10:57:42 -08:00
committed by Jonathan Hui
parent 17168e9ba1
commit b99f434a88
2 changed files with 43 additions and 73 deletions
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src/core/thread/lowpan.cpp
+37 -62
View File
@@ -668,17 +668,16 @@ int Lowpan::DecompressBaseHeader(Ip6::Header & aIp6Header,
NetworkData::Leader &networkData = Get<NetworkData::Leader>();
otError error = OT_ERROR_PARSE;
const uint8_t * cur = aBuf;
uint16_t remaining = aBufLength;
const uint8_t * end = aBuf + aBufLength;
uint16_t hcCtl;
Context srcContext, dstContext;
bool srcContextValid = true, dstContextValid = true;
uint8_t nextHeader;
uint8_t * bytes;
VerifyOrExit(remaining >= 2);
VerifyOrExit(cur + 2 <= end);
hcCtl = ReadUint16(cur);
cur += 2;
remaining -= 2;
// check Dispatch bits
VerifyOrExit((hcCtl & kHcDispatchMask) == kHcDispatch);
@@ -689,7 +688,7 @@ int Lowpan::DecompressBaseHeader(Ip6::Header & aIp6Header,
if ((hcCtl & kHcContextId) != 0)
{
VerifyOrExit(remaining >= 1);
VerifyOrExit(cur < end);
if (networkData.GetContext(cur[0] >> 4, srcContext) != OT_ERROR_NONE)
{
@@ -702,7 +701,6 @@ int Lowpan::DecompressBaseHeader(Ip6::Header & aIp6Header,
}
cur++;
remaining--;
}
else
{
@@ -716,7 +714,7 @@ int Lowpan::DecompressBaseHeader(Ip6::Header & aIp6Header,
// Traffic Class and Flow Label
if ((hcCtl & kHcTrafficFlowMask) != kHcTrafficFlow)
{
VerifyOrExit(remaining >= 1);
VerifyOrExit(cur < end);
bytes = reinterpret_cast<uint8_t *>(&aIp6Header);
bytes[1] |= (cur[0] & 0xc0) >> 2;
@@ -726,27 +724,24 @@ int Lowpan::DecompressBaseHeader(Ip6::Header & aIp6Header,
bytes[0] |= (cur[0] >> 2) & 0x0f;
bytes[1] |= (cur[0] << 6) & 0xc0;
cur++;
remaining--;
}
if ((hcCtl & kHcFlowLabel) == 0)
{
VerifyOrExit(remaining >= 3);
VerifyOrExit(cur + 3 <= end);
bytes[1] |= cur[0] & 0x0f;
bytes[2] |= cur[1];
bytes[3] |= cur[2];
cur += 3;
remaining -= 3;
}
}
// Next Header
if ((hcCtl & kHcNextHeader) == 0)
{
VerifyOrExit(remaining >= 1);
VerifyOrExit(cur < end);
aIp6Header.SetNextHeader(cur[0]);
cur++;
remaining--;
aCompressedNextHeader = false;
}
else
@@ -770,10 +765,9 @@ int Lowpan::DecompressBaseHeader(Ip6::Header & aIp6Header,
break;
default:
VerifyOrExit(remaining >= 1);
VerifyOrExit(cur < end);
aIp6Header.SetHopLimit(cur[0]);
cur++;
remaining--;
break;
}
@@ -783,28 +777,25 @@ int Lowpan::DecompressBaseHeader(Ip6::Header & aIp6Header,
case kHcSrcAddrMode0:
if ((hcCtl & kHcSrcAddrContext) == 0)
{
VerifyOrExit(remaining >= sizeof(Ip6::Address));
VerifyOrExit(cur + sizeof(Ip6::Address) <= end);
memcpy(&aIp6Header.GetSource(), cur, sizeof(aIp6Header.GetSource()));
cur += sizeof(Ip6::Address);
remaining -= sizeof(Ip6::Address);
}
break;
case kHcSrcAddrMode1:
VerifyOrExit(remaining >= Ip6::Address::kInterfaceIdentifierSize);
VerifyOrExit(cur + Ip6::Address::kInterfaceIdentifierSize <= end);
aIp6Header.GetSource().SetIid(cur);
cur += Ip6::Address::kInterfaceIdentifierSize;
remaining -= Ip6::Address::kInterfaceIdentifierSize;
break;
case kHcSrcAddrMode2:
VerifyOrExit(remaining >= 2);
VerifyOrExit(cur + 2 <= end);
aIp6Header.GetSource().mFields.m8[11] = 0xff;
aIp6Header.GetSource().mFields.m8[12] = 0xfe;
memcpy(aIp6Header.GetSource().mFields.m8 + 14, cur, 2);
cur += 2;
remaining -= 2;
break;
case kHcSrcAddrMode3:
@@ -833,26 +824,23 @@ int Lowpan::DecompressBaseHeader(Ip6::Header & aIp6Header,
{
case kHcDstAddrMode0:
VerifyOrExit((hcCtl & kHcDstAddrContext) == 0);
VerifyOrExit(remaining >= sizeof(Ip6::Address));
VerifyOrExit(cur + sizeof(Ip6::Address) <= end);
memcpy(&aIp6Header.GetDestination(), cur, sizeof(aIp6Header.GetDestination()));
cur += sizeof(Ip6::Address);
remaining -= sizeof(Ip6::Address);
break;
case kHcDstAddrMode1:
VerifyOrExit(remaining >= Ip6::Address::kInterfaceIdentifierSize);
VerifyOrExit(cur + Ip6::Address::kInterfaceIdentifierSize <= end);
aIp6Header.GetDestination().SetIid(cur);
cur += Ip6::Address::kInterfaceIdentifierSize;
remaining -= Ip6::Address::kInterfaceIdentifierSize;
break;
case kHcDstAddrMode2:
VerifyOrExit(remaining >= 2);
VerifyOrExit(cur + 2 <= end);
aIp6Header.GetDestination().mFields.m8[11] = 0xff;
aIp6Header.GetDestination().mFields.m8[12] = 0xfe;
memcpy(aIp6Header.GetDestination().mFields.m8 + 14, cur, 2);
cur += 2;
remaining -= 2;
break;
case kHcDstAddrMode3:
@@ -884,34 +872,30 @@ int Lowpan::DecompressBaseHeader(Ip6::Header & aIp6Header,
switch (hcCtl & kHcDstAddrModeMask)
{
case kHcDstAddrMode0:
VerifyOrExit(remaining >= sizeof(Ip6::Address));
VerifyOrExit(cur + sizeof(Ip6::Address) <= end);
memcpy(aIp6Header.GetDestination().mFields.m8, cur, sizeof(Ip6::Address));
cur += sizeof(Ip6::Address);
remaining -= sizeof(Ip6::Address);
break;
case kHcDstAddrMode1:
VerifyOrExit(remaining >= 6);
VerifyOrExit(cur + 6 <= end);
aIp6Header.GetDestination().mFields.m8[1] = cur[0];
memcpy(aIp6Header.GetDestination().mFields.m8 + 11, cur + 1, 5);
cur += 6;
remaining -= 6;
break;
case kHcDstAddrMode2:
VerifyOrExit(remaining >= 4);
VerifyOrExit(cur + 4 <= end);
aIp6Header.GetDestination().mFields.m8[1] = cur[0];
memcpy(aIp6Header.GetDestination().mFields.m8 + 13, cur + 1, 3);
cur += 4;
remaining -= 4;
break;
case kHcDstAddrMode3:
VerifyOrExit(remaining >= 1);
VerifyOrExit(cur < end);
aIp6Header.GetDestination().mFields.m8[1] = 0x02;
aIp6Header.GetDestination().mFields.m8[15] = cur[0];
cur++;
remaining--;
break;
}
}
@@ -920,7 +904,7 @@ int Lowpan::DecompressBaseHeader(Ip6::Header & aIp6Header,
switch (hcCtl & kHcDstAddrModeMask)
{
case 0:
VerifyOrExit(remaining >= 6);
VerifyOrExit(cur + 6 <= end);
VerifyOrExit(dstContextValid);
aIp6Header.GetDestination().mFields.m8[1] = cur[0];
aIp6Header.GetDestination().mFields.m8[2] = cur[1];
@@ -928,7 +912,6 @@ int Lowpan::DecompressBaseHeader(Ip6::Header & aIp6Header,
memcpy(aIp6Header.GetDestination().mFields.m8 + 4, dstContext.mPrefix, 8);
memcpy(aIp6Header.GetDestination().mFields.m8 + 12, cur + 2, 4);
cur += 6;
remaining -= 6;
break;
default:
@@ -939,7 +922,7 @@ int Lowpan::DecompressBaseHeader(Ip6::Header & aIp6Header,
if ((hcCtl & kHcNextHeader) != 0)
{
VerifyOrExit(remaining >= 1);
VerifyOrExit(cur < end);
SuccessOrExit(DispatchToNextHeader(cur[0], nextHeader));
aIp6Header.SetNextHeader(nextHeader);
}
@@ -952,9 +935,9 @@ exit:
int Lowpan::DecompressExtensionHeader(Message &aMessage, const uint8_t *aBuf, uint16_t aBufLength)
{
otError error = OT_ERROR_PARSE;
const uint8_t * cur = aBuf;
uint16_t remaining = aBufLength;
otError error = OT_ERROR_PARSE;
const uint8_t * cur = aBuf;
const uint8_t * end = aBuf + aBufLength;
uint8_t hdr[2];
uint8_t len;
uint8_t nextHeader;
@@ -963,33 +946,30 @@ int Lowpan::DecompressExtensionHeader(Message &aMessage, const uint8_t *aBuf, ui
Ip6::OptionPad1 optionPad1;
Ip6::OptionPadN optionPadN;
VerifyOrExit(remaining >= 1);
VerifyOrExit(cur < end);
cur++;
remaining--;
// next header
if (ctl & kExtHdrNextHeader)
{
VerifyOrExit(remaining >= 1);
VerifyOrExit(cur < end);
len = cur[0];
cur++;
remaining--;
VerifyOrExit(remaining >= len);
VerifyOrExit(cur + len <= end);
SuccessOrExit(DispatchToNextHeader(cur[len], nextHeader));
hdr[0] = static_cast<uint8_t>(nextHeader);
}
else
{
VerifyOrExit(remaining >= 2);
VerifyOrExit(cur + 2 <= end);
hdr[0] = cur[0];
len = cur[1];
cur += 2;
remaining -= 2;
VerifyOrExit(remaining >= len);
VerifyOrExit(cur + len <= end);
}
// length
@@ -1032,15 +1012,14 @@ exit:
int Lowpan::DecompressUdpHeader(Ip6::UdpHeader &aUdpHeader, const uint8_t *aBuf, uint16_t aBufLength)
{
otError error = OT_ERROR_PARSE;
const uint8_t *cur = aBuf;
uint16_t remaining = aBufLength;
otError error = OT_ERROR_PARSE;
const uint8_t *cur = aBuf;
const uint8_t *end = aBuf + aBufLength;
uint8_t udpCtl;
VerifyOrExit(remaining >= 1);
VerifyOrExit(cur < end);
udpCtl = cur[0];
cur++;
remaining--;
VerifyOrExit((udpCtl & kUdpDispatchMask) == kUdpDispatch);
@@ -1050,35 +1029,31 @@ int Lowpan::DecompressUdpHeader(Ip6::UdpHeader &aUdpHeader, const uint8_t *aBuf,
switch (udpCtl & kUdpPortMask)
{
case 0:
VerifyOrExit(remaining >= 4);
VerifyOrExit(cur + 4 <= end);
aUdpHeader.SetSourcePort(ReadUint16(cur));
aUdpHeader.SetDestinationPort(ReadUint16(cur + 2));
cur += 4;
remaining -= 4;
break;
case 1:
VerifyOrExit(remaining >= 3);
VerifyOrExit(cur + 3 <= end);
aUdpHeader.SetSourcePort(ReadUint16(cur));
aUdpHeader.SetDestinationPort(0xf000 | cur[2]);
cur += 3;
remaining -= 3;
break;
case 2:
VerifyOrExit(remaining >= 3);
VerifyOrExit(cur + 3 <= end);
aUdpHeader.SetSourcePort(0xf000 | cur[0]);
aUdpHeader.SetDestinationPort(ReadUint16(cur + 1));
cur += 3;
remaining -= 3;
break;
case 3:
VerifyOrExit(remaining >= 1);
VerifyOrExit(cur < end);
aUdpHeader.SetSourcePort(0xf0b0 | (cur[0] >> 4));
aUdpHeader.SetDestinationPort(0xf0b0 | (cur[0] & 0xf));
cur += 1;
remaining -= 1;
cur++;
break;
}
@@ -1089,7 +1064,7 @@ int Lowpan::DecompressUdpHeader(Ip6::UdpHeader &aUdpHeader, const uint8_t *aBuf,
}
else
{
VerifyOrExit(remaining >= 2);
VerifyOrExit(cur + 2 <= end);
aUdpHeader.SetChecksum(ReadUint16(cur));
cur += 2;
}
src/core/thread/lowpan.hpp
+6 -11
View File
@@ -92,9 +92,9 @@ public:
*
*/
BufferWriter(uint8_t *aBuf, uint16_t aLength)
: mWritePointer(aBuf)
, mEndPointer(aBuf + aLength)
{
mWritePointer = aBuf;
mRemainingLength = aLength;
}
/**
@@ -106,7 +106,7 @@ public:
* @retval FALSE Insufficient buffer space to write the requested number of bytes.
*
*/
bool CanWrite(uint8_t aLength) const { return mRemainingLength >= aLength; }
bool CanWrite(uint8_t aLength) const { return (mWritePointer + aLength) <= mEndPointer; }
/**
* This method returns the current write pointer value.
@@ -121,8 +121,8 @@ public:
*
* @param[in] aLength Number of bytes to advance.
*
* @retval TRUE Enough buffer space is available to advance the requested number of bytes.
* @retval FALSE Insufficient buffer space to advance the requested number of bytes.
* @retval OT_ERROR_NONE Enough buffer space is available to advance the requested number of bytes.
* @retval OT_ERROR_NO_BUFS Insufficient buffer space to advance the requested number of bytes.
*
*/
otError Advance(uint8_t aLength)
@@ -130,9 +130,7 @@ public:
otError error = OT_ERROR_NONE;
VerifyOrExit(CanWrite(aLength), error = OT_ERROR_NO_BUFS);
mWritePointer += aLength;
mRemainingLength -= aLength;
exit:
return error;
@@ -154,7 +152,6 @@ public:
VerifyOrExit(CanWrite(sizeof(aByte)), error = OT_ERROR_NO_BUFS);
*mWritePointer++ = aByte;
mRemainingLength--;
exit:
return error;
@@ -178,7 +175,6 @@ public:
memcpy(mWritePointer, aBuf, aLength);
mWritePointer += aLength;
mRemainingLength -= aLength;
exit:
return error;
@@ -207,7 +203,6 @@ public:
assert(rval == aLength);
mWritePointer += aLength;
mRemainingLength -= aLength;
exit:
return error;
@@ -215,7 +210,7 @@ public:
private:
uint8_t *mWritePointer;
uint16_t mRemainingLength;
uint8_t *mEndPointer;
};
/**