Files
meshcore-wch/User/meshcore/packets/group.c
2025-12-30 08:04:26 +01:00

107 lines
3.1 KiB
C

#include "ch32v30x_rtc.h"
#include "meshcore/meshframing.h"
#include "meshcore/packetstructs.h"
#include "group.h"
#include "lib/config.h"
#include "util/hexdump.h"
#include "util/log.h"
#include "string.h"
#define TAG "GroupMessage"
void sendGroupMessage (const GroupTextMessage *msg) {
// Prepare values locally instead of modifying msg
Channel *channel = &(persistent.channels[msg->keyIndex]);
uint8_t flags = 0;
int32_t timestamp = RTC_GetCounter();
FrameStruct frame;
frame.header = ROUTE_TYPE_FLOOD | PAYLOAD_TYPE_GRP_TXT | PAYLOAD_VERSION_0;
frame.path.pathLen = 0;
size_t offset = 0;
frame.payload[offset++] = channel->hash;
// Build encryption buffer directly on stack (no extra large buffer)
uint8_t buf[180]; // enough for timestamp + flags + text
size_t buf_offset = 0;
memcpy (buf + buf_offset, &timestamp, sizeof (timestamp));
buf_offset += sizeof (timestamp);
buf[buf_offset++] = flags;
size_t textLen = strlen ((const char *)msg->text);
if (buf_offset + textLen > sizeof (buf)) {
textLen = sizeof (buf) - buf_offset;
}
memcpy (buf + buf_offset, msg->text, textLen);
buf_offset += textLen;
hexdump ("TxDumpDec", buf, buf_offset);
// Encrypt and MAC directly into frame payload after channelHash
size_t olen = 0;
encrypt_then_mac (channel->key, 16, buf, buf_offset, &frame.payload[offset], &olen);
frame.payloadLen = olen + 1; // +1 for channelHash
channel->timestamp = timestamp;
LoRaTransmit (&frame);
}
void makeSendGroupMessage (char *txt, uint8_t keyIndex) {
GroupTextMessage msg;
strcpy ((char *)msg.text, persistent.nodeName);
strcat ((char *)msg.text, ": ");
strcat ((char *)msg.text, txt);
msg.keyIndex = keyIndex;
sendGroupMessage (&msg);
return;
}
void decodeGroupMessage (const FrameStruct *frame) {
GroupTextMessage msg;
memset (&msg, 0, sizeof (msg));
if ((frame->header & PAYLOAD_TYPE_MASK) != PAYLOAD_TYPE_GRP_TXT) {
MESH_LOGW (TAG, "Not a group text");
return;
}
unsigned char index = 0;
msg.channelHash = frame->payload[index++];
unsigned char tmp[184];
Channel *channel = NULL;
uint8_t i = 0;
do {
channel = getChannel (msg.channelHash, i);
if (channel == NULL) {
MESH_LOGW (TAG, "Channel hash %d not found", msg.channelHash);
return;
}
if (mac_then_decrypt (channel->key, 16, frame->payload + index, frame->payloadLen - index, tmp) != 0) {
MESH_LOGW (TAG, "HMAC failed on grouphash key %d", msg.channelHash);
i++;
continue;
} else {
unsigned char plaintextLen = frame->payloadLen - index;
index = 0;
memcpy (&msg.timestamp, tmp + index, 4);
index += 4;
msg.flags = tmp[index++];
memcpy (msg.text, tmp + index, plaintextLen - index);
channel->timestamp = RTC_GetCounter();
printf ("Message from channel %s: %s\n", channel->name, msg.text);
break;
}
} while (channel != NULL);
}