Basic packet processing. No encryption or resending yet.
This commit is contained in:
Scott Duensing
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395899445a
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c45b89c8ab
3 changed files with 294 additions and 0 deletions
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@ -63,6 +63,7 @@ HEADERS = \
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$$SHARED/thirdparty/blowfish-api/blowfish.h \
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$$SHARED/thirdparty/blowfish-api/blowfish.h \
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$$SHARED/thirdparty/ini/src/ini.h \
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$$SHARED/thirdparty/ini/src/ini.h \
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$$SHARED/primes.h \
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$$SHARED/primes.h \
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$$SHARED/packet.h \
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src/config.h \
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src/config.h \
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$$SHARED/util.h \
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$$SHARED/util.h \
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src/gui/msgbox.h \
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src/gui/msgbox.h \
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@ -105,6 +106,7 @@ SOURCES = \
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$$SHARED/thirdparty/memwatch/memwatch.c \
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$$SHARED/thirdparty/memwatch/memwatch.c \
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$$SHARED/thirdparty/blowfish-api/blowfish.c \
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$$SHARED/thirdparty/blowfish-api/blowfish.c \
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$$SHARED/thirdparty/ini/src/ini.c \
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$$SHARED/thirdparty/ini/src/ini.c \
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$$SHARED/packet.c \
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src/config.c \
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src/config.c \
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$$SHARED/memory.c \
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$$SHARED/memory.c \
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src/gui/msgbox.c \
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src/gui/msgbox.c \
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195
shared/packet.c
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195
shared/packet.c
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/*
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* Kangaroo Punch MultiPlayer Game Server Mark II
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* Copyright (C) 2020-2021 Scott Duensing
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <https://www.gnu.org/licenses/>.
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*
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*/
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#include "packet.h"
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static uint8_t packetCRC(char *data, uint16_t length, uint8_t startAt);
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static uint8_t packetCRC(char *data, uint16_t length, uint8_t startAt) {
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uint16_t x = 0;
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for (x=0; x<length; x++) {
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startAt += data[x];
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}
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return startAt;
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}
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uint8_t packetDecode(PacketThreadDataT *threadData, PacketDecodeDataT *data, char *input, uint16_t length) {
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uint16_t x = 0;
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char c = 0;
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// input and inputLength are incoming raw data or NULL and 0 to continue processing already received data.
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// Returns 1 on packet ready, 0 on still waiting.
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// Is there input data to add to the queue?
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if (input != NULL && length > 0) {
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for (x=0; x<length; x++) {
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threadData->decodeQueue[threadData->decodeQueueHead++] = input[x];
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if (threadData->decodeQueueHead >= PACKET_INPUT_QUEUE_SIZE) {
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threadData->decodeQueueHead = 0;
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}
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}
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}
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while (1) {
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// Do we have data to process?
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if (threadData->decodeQueueHead == threadData->decodeQueueTail) return 0;
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// Get next byte.
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c = threadData->decodeQueue[threadData->decodeQueueTail++];
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if (threadData->decodeQueueTail >= PACKET_INPUT_QUEUE_SIZE) {
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threadData->decodeQueueTail = 0;
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}
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// New packet?
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if (threadData->newPacket) {
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threadData->newPacket = 0;
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threadData->inEscape = 0;
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data->length = 0;
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}
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// Are we escaped?
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if (threadData->inEscape) {
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threadData->inEscape = 0;
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// Is this the end of the packet?
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if (c != PACKET_FRAME) {
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threadData->newPacket = 1;
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// Check CRC.
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if (threadData->decodeBuffer[data->length - 1] != packetCRC(threadData->decodeBuffer, data->length - 1, 0)) continue;
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// Fill decoded data fields.
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data->packetType = threadData->decodeBuffer[1];
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data->channel = threadData->decodeBuffer[2];
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// ***TODO*** Blowfish Decryption.
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if (threadData->decodeBuffer[0] & 32) {
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}
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// Copy packet data to new buffer.
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data->data = (char *)malloc(data->length - 4); // 4 for 3 byte header and 1 byte CRC.
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if (!data) continue;
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memcpy(data->data, &threadData->decodeBuffer[3], data->length - 4); // Skip header and CRC.
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break;
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}
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} else {
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// Are we escaping?
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if (c == PACKET_FRAME) {
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// Yes. Don't add this byte.
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threadData->inEscape = 1;
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continue;
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}
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// Did we overflow?
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if (data->length >= PACKET_MAX) {
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// Yup. Dump it.
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threadData->newPacket = 1;
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continue;
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}
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// Add byte to packet.
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threadData->decodeBuffer[data->length++] = c;
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}
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}
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return 1;
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}
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uint8_t packetEncode(PacketThreadDataT *threadData, PacketEncodeDataT *data, char *input, uint16_t length) {
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uint8_t crc = 0;
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uint8_t control = 0;
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// Returns 1 on success, 0 on failure.
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// Packet too large?
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if (length > PACKET_MAX) return 0;
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data->dataPointer = NULL;
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data->length = 0;
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data->sequence = threadData->sequence++;
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// Make needed header bytes.
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control = (data->control << 6) + (data->encrypt << 5) + (data->sequence & 0x1f);
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// Calculate CRC over header bytes and payload.
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crc = packetCRC((char *)&control, 1, crc);
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crc = packetCRC((char *)&data->packetType, 1, crc);
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crc = packetCRC((char *)&data->channel, 1, crc);
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crc = packetCRC(input, length, crc);
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// Add header bytes.
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threadData->encodeBuffer[data->length++] = control;
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if (control == PACKET_FRAME) threadData->encodeBuffer[data->length++] = PACKET_FRAME;
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threadData->encodeBuffer[data->length++] = data->packetType;
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if (data->packetType == PACKET_FRAME) threadData->encodeBuffer[data->length++] = PACKET_FRAME;
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threadData->encodeBuffer[data->length++] = data->channel;
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if (data->channel == PACKET_FRAME) threadData->encodeBuffer[data->length++] = PACKET_FRAME;
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// ***TODO*** Blowfish Encryption.
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if (data->encrypt) {
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}
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// Add payload.
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while (length--) {
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// Is this a frame character? If so, escape it.
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if (*input == PACKET_FRAME) threadData->encodeBuffer[data->length++] = PACKET_FRAME;
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// Add data.
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threadData->encodeBuffer[data->length++] = *input++;
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}
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// Add CRC.
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threadData->encodeBuffer[data->length++] = crc;
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if (crc == PACKET_FRAME) threadData->encodeBuffer[data->length++] = PACKET_FRAME;
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// Mark end of packet.
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threadData->encodeBuffer[data->length++] = PACKET_FRAME;
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threadData->encodeBuffer[data->length++] = 0;
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return 1;
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}
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PacketThreadDataT *packetThreadDataCreate(void) {
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PacketThreadDataT *data = NULL;
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data = (PacketThreadDataT *)malloc(sizeof(PacketThreadDataT));
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if (data) {
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data->sequence = 0;
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data->decodeQueueHead = 0;
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data->decodeQueueTail = 0;
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data->newPacket = 1;
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}
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return data;
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}
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void packetThreadDataDestroy(PacketThreadDataT **data) {
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PacketThreadDataT *d = *data;
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free(d);
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d = NULL;
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*data = d;
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}
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97
shared/packet.h
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97
shared/packet.h
Normal file
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@ -0,0 +1,97 @@
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/*
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* Kangaroo Punch MultiPlayer Game Server Mark II
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* Copyright (C) 2020-2021 Scott Duensing
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <https://www.gnu.org/licenses/>.
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*
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*/
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#ifndef PACKET_H
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#define PACKET_H
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#include "os.h"
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/*
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* Packet format (without framing):
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*
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* Byte 01: cces ssss - Two control bits, one encryption bit, five sequence bits.
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* Byte 02: pppp pppp - Eight bits, packet type.
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* Byte 03: cccc cccc - Eight bits, channel.
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* Byte 04: dddd dddd \
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* Byte ..: dddd dddd > Packet payload.
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* Byte X0: dddd dddd /
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* Byte X1: cccc cccc - Checksum
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*
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*/
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#define PACKET_MAX 1024 // Maximum number of bytes per packet
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#define PACKET_SEQUENCE_MAX 32 // Five bits of data
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#define PACKET_INPUT_QUEUE_SIZE 4096
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#define PACKET_BUFFER_SIZE (PACKET_MAX * 2 + 2 + 8) // Worst case, every byte is a PACKET_FRAME. Add two for ending frame. Add 8 for worst case header and CRC.
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#define PACKET_FRAME 0x7e
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#define PACKET_CONTROL_DAT 0 // Regular data packet.
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#define PACKET_CONTROL_RTX 1 // Retransmission packet.
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#define PACKET_CONTROL_NAK 2 // Negative acknowledge.
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#define PACKET_TYPE_NONE 0 // No packet.
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typedef struct PacketDecodeDataS {
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// Output
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uint8_t packetType; // One of PACKET_TYPE_*
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char *data; // Buffer received. MUST FREE.
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uint16_t length; // Length of buffer.
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uint8_t channel; // Which data channel it arrived on.
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} PacketDecodeDataT;
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typedef struct PacketEncodeDataS {
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// Input
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uint8_t control; // One of PACKET_CONTROL_*
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uint8_t packetType; // One of PACKET_TYPE_*
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uint8_t channel; // Which data channel to use.
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uint8_t encrypt; // Do we want the packet encrypted?
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// Input & Output
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uint16_t sequence; // For NAK packets, input the sequence number we missed. Other packets returns the sequence of this packet.
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// Output
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char *dataPointer; // Buffer ready to send. DO NOT FREE.
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uint16_t length; // Length of buffer.
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} PacketEncodeDataT;
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typedef struct PacketThreadDataS {
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// Internal state per thread for packet processing.
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uint8_t sequence;
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char decodeBuffer[PACKET_MAX];
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char encodeBuffer[PACKET_BUFFER_SIZE];
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char decodeQueue[PACKET_INPUT_QUEUE_SIZE];
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uint16_t decodeQueueHead;
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uint16_t decodeQueueTail;
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uint8_t inEscape;
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uint8_t newPacket;
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} PacketThreadDataT;
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uint8_t packetDecode(PacketThreadDataT *threadData, PacketDecodeDataT *data, char *input, uint16_t length);
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uint8_t packetEncode(PacketThreadDataT *threadData, PacketEncodeDataT *data, char *input, uint16_t length);
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PacketThreadDataT *packetThreadDataCreate(void);
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void packetThreadDataDestroy(PacketThreadDataT **data);
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#endif // PACKET_H
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