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Switch to using an unaligned read helper that does the reads via memcpy. #75

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Switch to using an unaligned read helper that does the reads via memcpy. #75

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9 changes: 9 additions & 0 deletions include/endianness.hh
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Original file line number Diff line number Diff line change
@@ -1,6 +1,7 @@
// Copyright SCI Semiconductor and CHERIoT Contributors.
// SPDX-License-Identifier: MIT

#include "cdefs.h"
#include <stdint.h>

uint16_t constexpr ntohs(uint16_t value)
Expand All @@ -24,3 +25,11 @@ uint16_t constexpr htons(uint16_t value)
#endif
;
}

template<class T>
__always_inline T read_unaligned(const void *p)
{
T val;
__builtin_memcpy(&val, p, sizeof(T));
return val;
}
24 changes: 12 additions & 12 deletions lib/dns/dns.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -808,12 +808,12 @@ namespace
if (isIPv6)
{
queryResult.kind = NetworkAddress::AddressKindIPv6;
uint16_t *ipv6 = reinterpret_cast<uint16_t *>(&queryResult.ipv6[0]);
uint8_t *ipv6 = queryResult.ipv6;
// Enforce machine byte order by block of 2 byte.
for (int i = 0; i < 8; i++)
{
*ipv6++ = ntohs(
*reinterpret_cast<uint16_t *>(dnsPacket + currentOffset));
*ipv6++ =
ntohs(read_unaligned<uint16_t>(dnsPacket + currentOffset));
currentOffset += 2;
}
}
Expand Down Expand Up @@ -1110,15 +1110,15 @@ __cheri_compartment("DNS") int network_host_resolve(Timeout *timeout,
{
Debug::log("Resolved {} -> {}:{}:{}:{}:{}:{}:{}:{}",
hostname,
*reinterpret_cast<uint16_t *>(&queryResult.ipv6[0]),
*reinterpret_cast<uint16_t *>(&queryResult.ipv6[2]),
*reinterpret_cast<uint16_t *>(&queryResult.ipv6[4]),
*reinterpret_cast<uint16_t *>(&queryResult.ipv6[6]),
*reinterpret_cast<uint16_t *>(&queryResult.ipv6[8]),
*reinterpret_cast<uint16_t *>(&queryResult.ipv6[10]),
*reinterpret_cast<uint16_t *>(&queryResult.ipv6[12]),
*reinterpret_cast<uint16_t *>(&queryResult.ipv6[14]),
*reinterpret_cast<uint16_t *>(&queryResult.ipv6[16]));
read_unaligned<uint16_t>(&queryResult.ipv6[0]),
read_unaligned<uint16_t>(&queryResult.ipv6[2]),
read_unaligned<uint16_t>(&queryResult.ipv6[4]),
read_unaligned<uint16_t>(&queryResult.ipv6[6]),
read_unaligned<uint16_t>(&queryResult.ipv6[8]),
read_unaligned<uint16_t>(&queryResult.ipv6[10]),
read_unaligned<uint16_t>(&queryResult.ipv6[12]),
read_unaligned<uint16_t>(&queryResult.ipv6[14]),
read_unaligned<uint16_t>(&queryResult.ipv6[16]));
}

// We are now good to process the next lookup.
Expand Down
2 changes: 1 addition & 1 deletion lib/dns/protocol-headers.hh
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Original file line number Diff line number Diff line change
Expand Up @@ -68,7 +68,7 @@ uint16_t compute_ipv4_checksum(const uint8_t *header, uint16_t length)

while (length > 1)
{
sum += *reinterpret_cast<const uint16_t *>(header);
sum += read_unaligned<uint16_t>(header);
header += 2;
length -= 2;
}
Expand Down
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