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packet.cpp
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packet.cpp
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#include "packet.h"
Packet::Packet(char data[24], socket& socket,
const std::shared_ptr<KeyValueStore>& k)
: bod_len(readUInt32LE(data, 8)),
opaque(readUInt32LE(data, 12)),
key_len(readUInt16LE(data, 2)),
op(data[1]),
ext_len(data[4]) {
read(socket);
if (data[1] == static_cast<char>(OpCode::GET)) {
std::pair<bool, const FlaggedValue&> value{ k->get(key) };
if (value.first) {
respondToGet(socket, value.second, true);
} else {
std::string msg = "Key not found";
std::vector<char> val(msg.cbegin(), msg.cend());
respondToGet(socket, FlaggedValue{ val, 0 }, false);
}
} else if (data[1] == static_cast<char>(OpCode::SET)) {
k->set(key, FlaggedValue{ val, flags });
respondToSet(socket);
}
}
void Packet::read(socket& socket) {
std::uint32_t bytes_read = 0;
if (ext_len > 0) {
std::vector<char> extras(ext_len);
while (bytes_read < static_cast<std::uint32_t>(ext_len)) {
bytes_read += socket.receive(boost::asio::buffer(extras));
}
bytes_read = 0;
if (extras.size() > 4) {
char flags_buf[4] = { extras[0], extras[1], extras[2], extras[3] };
flags = readUInt32LE(flags_buf, 0);
}
}
if (key_len > 0) {
key.resize(key_len);
while (bytes_read < key_len) {
bytes_read += socket.receive(boost::asio::buffer(key));
}
bytes_read = 0;
}
if (bod_len > key_len) {
std::uint32_t val_len = bod_len - key_len - ext_len;
val.resize(val_len);
while (bytes_read < val_len) {
bytes_read += socket.receive(boost::asio::buffer(val));
}
}
}
// Must have extras.
// May have key.
// May have value.
void Packet::respondToSet(socket& socket) {
unsigned char res[24] = { 0x81, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01 };
writeUInt32LE(&res[12], opaque);
try {
boost::asio::write(socket, boost::asio::buffer(res));
} catch (std::exception& e) {
std::cout << e.what() << std::endl;
}
}
// MUST have extras.
// MAY have key.
// MAY have value.
void Packet::respondToGet(socket& socket, const FlaggedValue& fv, bool found) {
unsigned char res[28] = { 0x81, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00 };
writeUInt32LE(&res[8], fv.value.size() + 4);
writeUInt32LE(&res[12], opaque);
writeUInt32LE(&res[24], fv.flags);
// Section 4.1:
// If the status code of a response packet is non-nil, the body of the packet
// will contain a textual error message.
if (!found) {
res[7] = 0x01;
}
try {
boost::asio::write(socket, boost::asio::buffer(res));
boost::asio::write(socket, boost::asio::buffer(fv.value));
} catch (std::exception& e) {
std::cerr << e.what() << std::endl;
}
}
// x86-64 is little endian, but this won't work elsewhere...
std::uint32_t Packet::readUInt32LE(char data[32], size_t offset) {
return htonl(*reinterpret_cast<std::uint32_t*>(&data[offset]));
}
std::uint16_t Packet::readUInt16LE(char data[32], size_t offset) {
return htons(*reinterpret_cast<std::uint16_t*>(&data[offset]));
}
void Packet::writeUInt32LE(unsigned char* const data, std::uint32_t val) {
data[0] = (val & 0xFF000000) >> 24;
data[1] = (val & 0x00FF0000) >> 16;
data[2] = (val & 0x0000FF00) >> 8;
data[3] = val & 0x000000FF;
}
void Packet::printPacket(const char* const buf, const size_t len) {
for (size_t i = 0; i < len; ++i) {
if (i % 8 == 0) {
std::cout << std::endl;
}
printf("%02hhx|", buf[i]);
}
std::cout << std::endl;
}
void Packet::printPacket(const std::vector<char>& buf) {
for (size_t i = 0; i < buf.size(); ++i) {
if (i % 8 == 0) {
std::cout << std::endl;
}
printf("%02hhx|", buf[i]);
}
std::cout << std::endl;
}