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Atmosphere/stratosphere/dmnt.gen2/source/dmnt2_gdb_packet_io.cpp

194 lines
6.6 KiB
C++

/*
* Copyright (c) Atmosphère-NX
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stratosphere.hpp>
#include "dmnt2_gdb_packet_io.hpp"
#include "dmnt2_debug_log.hpp"
namespace ams::dmnt {
namespace {
constexpr char BreakCharacter = '\x03'; /* ctrl-c */
constexpr int DecodeHex(char c) {
if ('a' <= c && c <= 'f') {
return 10 + (c - 'a');
} else if ('A' <= c && c <= 'F') {
return 10 + (c - 'A');
} else if ('0' <= c && c <= '9') {
return 0 + (c - '0');
} else {
return -1;
}
}
constexpr char EncodeHex(u8 v) {
return "0123456789abcdef"[v & 0xF];
}
}
void GdbPacketIo::SendPacket(bool *out_break, const char *src, TransportSession *session) {
/* Default to not breaked. */
*out_break = false;
/* Send a packet. */
while (true) {
std::scoped_lock lk(m_mutex);
size_t len = 0;
u8 checksum = 0;
while (src[len] != 0) {
checksum += static_cast<u8>(src[len++]);
}
char buffer[1 + GdbPacketBufferSize + 4];
buffer[0] = '$';
std::memcpy(buffer + 1, src, len);
buffer[1 + len] = '#';
buffer[2 + len] = EncodeHex(checksum >> 4);
buffer[3 + len] = EncodeHex(checksum >> 0);
buffer[4 + len] = 0;
if (session->PutString(buffer) < 0) {
/* Log (truncated) copy of packet. */
AMS_DMNT2_GDB_LOG_ERROR("Failed to send packet %s\n", buffer);
return;
}
if (m_no_ack) {
return;
}
/* Check to see if we need to retransmit. */
bool retransmit = false;
do {
if (const auto char_holder = session->GetChar(); char_holder) {
switch (*char_holder) {
case BreakCharacter:
*out_break = true;
return;
case '+':
return;
case '-':
retransmit = true;
break;
default:
break;
}
} else {
/* Log (truncated) copy of packet. */
AMS_DMNT2_GDB_LOG_ERROR("Failed to receive ack for %s\n", buffer);
return;
}
} while (!retransmit);
}
}
char *GdbPacketIo::ReceivePacket(bool *out_break, char *dst, size_t size, TransportSession *session) {
/* Default to not breaked. */
*out_break = false;
/* Receive a packet. */
while (true) {
/* Wait for data to be available. */
if (!session->WaitToBeReadable()) {
return nullptr;
}
/* Lock ourselves. */
std::scoped_lock lk(m_mutex);
/* Verify that we still have data immediately available. */
if (!session->WaitToBeReadable(0)) {
continue;
}
/* Prepare to parse. */
enum class State {
Initial,
PacketData,
ChecksumHigh,
ChecksumLow
};
State state = State::Initial;
u8 checksum = 0;
int csum_high = -1, csum_low = -1;
size_t count = 0;
/* Read characters. */
while (true) {
if (const auto char_holder = session->GetChar(); char_holder) {
const auto c = *char_holder;
switch (state) {
case State::Initial:
if (c == '$') {
state = State::PacketData;
} else if (c == BreakCharacter) {
*out_break = true;
return nullptr;
}
break;
case State::PacketData:
/* TODO: Escaped characters. */
if (c == '#') {
dst[count] = 0;
state = State::ChecksumHigh;
} else {
AMS_ABORT_UNLESS(count < size - 1);
checksum += static_cast<u8>(c);
dst[count++] = c;
}
break;
case State::ChecksumHigh:
csum_high = DecodeHex(c);
state = State::ChecksumLow;
break;
case State::ChecksumLow:
csum_low = DecodeHex(c);
if (m_no_ack) {
return dst;
} else {
const u8 expectsum = (static_cast<u8>(csum_high) << 4) | (static_cast<u8>(csum_low) << 0);
if (csum_high < 0 || csum_low < 0 || checksum != expectsum) {
/* Request retransmission. */
state = State::Initial;
checksum = 0;
csum_high = -1;
csum_low = -1;
count = 0;
session->PutChar('-');
} else {
session->PutChar('+');
return dst;
}
}
break;
}
} else {
return nullptr;
}
}
}
}
}