MMDVMHost-Private/AX25Control.cpp

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/*
* Copyright (C) 2020 Jonathan Naylor, G4KLX
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; version 2 of the License.
*
* This program is distributed in the hope that 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.
*/
#include "AX25Control.h"
#include "AX25Defines.h"
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#include "Utils.h"
#include "Log.h"
#include <cstdio>
#include <cassert>
#include <cstring>
#include <ctime>
// #define DUMP_AX25
const unsigned char BIT_MASK_TABLE[] = { 0x80U, 0x40U, 0x20U, 0x10U, 0x08U, 0x04U, 0x02U, 0x01U };
#define WRITE_BIT1(p,i,b) p[(i)>>3] = (b) ? (p[(i)>>3] | BIT_MASK_TABLE[(i)&7]) : (p[(i)>>3] & ~BIT_MASK_TABLE[(i)&7])
#define READ_BIT1(p,i) (p[(i)>>3] & BIT_MASK_TABLE[(i)&7])
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CAX25Control::CAX25Control(CAX25Network* network, bool trace) :
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m_network(network),
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m_trace(trace),
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m_enabled(true),
m_fp(NULL)
{
}
CAX25Control::~CAX25Control()
{
}
bool CAX25Control::writeModem(unsigned char *data, unsigned int len)
{
assert(data != NULL);
if (!m_enabled)
return false;
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if (m_trace)
decode(data, len);
CUtils::dump(1U, "AX.25 received packet", data, len);
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if (m_network == NULL)
return true;
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return m_network->write(data, len);
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}
unsigned int CAX25Control::readModem(unsigned char* data)
{
assert(data != NULL);
if (m_network == NULL)
return 0U;
if (!m_enabled)
return 0U;
unsigned int length = m_network->read(data, 500U);
if (length > 0U)
CUtils::dump(1U, "AX.25 transmitted packet", data, length);
return length;
}
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bool CAX25Control::openFile()
{
if (m_fp != NULL)
return true;
time_t t;
::time(&t);
struct tm* tm = ::localtime(&t);
char name[100U];
::sprintf(name, "AX25_%04d%02d%02d_%02d%02d%02d.ambe", tm->tm_year + 1900, tm->tm_mon + 1, tm->tm_mday, tm->tm_hour, tm->tm_min, tm->tm_sec);
m_fp = ::fopen(name, "wb");
if (m_fp == NULL)
return false;
::fwrite("AX25", 1U, 4U, m_fp);
return true;
}
bool CAX25Control::writeFile(const unsigned char* data, unsigned int length)
{
if (m_fp == NULL)
return false;
::fwrite(&length, 1U, sizeof(unsigned int), m_fp);
::fwrite(data, 1U, length, m_fp);
return true;
}
void CAX25Control::closeFile()
{
if (m_fp != NULL) {
::fclose(m_fp);
m_fp = NULL;
}
}
void CAX25Control::enable(bool enabled)
{
m_enabled = enabled;
}
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void CAX25Control::decode(const unsigned char* data, unsigned int length)
{
assert(data != NULL);
assert(length >= 15U);
std::string text;
bool more = decodeAddress(data + 7U, text);
text += '>';
decodeAddress(data + 0U, text);
unsigned int n = 14U;
while (more && n < length) {
text += ',';
more = decodeAddress(data + n, text, true);
n += 7U;
}
text += ' ';
if ((data[n] & 0x01U) == 0x00U) {
// I frame
char t[20U];
::sprintf(t, "<I S%u R%u>", (data[n] >> 1) & 0x07U, (data[n] >> 5) & 0x07U);
text += t;
} else {
if ((data[n] & 0x02U) == 0x00U) {
// S frame
char t[20U];
switch (data[n] & 0x0FU) {
case 0x01U:
sprintf(t, "<RR R%u>", (data[n] >> 5) & 0x07U);
break;
case 0x05U:
sprintf(t, "<RNR R%u>", (data[n] >> 5) & 0x07U);
break;
case 0x09U:
sprintf(t, "<REJ R%u>", (data[n] >> 5) & 0x07U);
break;
case 0x0DU:
sprintf(t, "<SREJ R%u>", (data[n] >> 5) & 0x07U);
break;
default:
sprintf(t, "<Unknown R%u>", (data[n] >> 5) & 0x07U);
break;
}
text += t;
LogMessage("AX.25, %s", text.c_str());
return;
} else {
// U frame
switch (data[n] & 0xEFU) {
case 0x6FU:
text += "<SABME>";
break;
case 0x2FU:
text += "<SABM>";
break;
case 0x43U:
text += "<DISC>";
break;
case 0x0FU:
text += "<DM>";
break;
case 0x63U:
text += "<UA>";
break;
case 0x87U:
text += "<FRMR>";
break;
case 0x03U:
text += "<UI>";
break;
case 0xAFU:
text += "<XID>";
break;
case 0xE3U:
text += "<TEST>";
break;
default:
text += "<Unknown>";
break;
}
if ((data[n] & 0xEFU) != 0x03U) {
LogMessage("AX.25, %s", text.c_str());
return;
}
}
}
n += 2U;
LogMessage("AX.25, %s %.*s", text.c_str(), length - n, data + n);
}
bool CAX25Control::decodeAddress(const unsigned char* data, std::string& text, bool isDigi) const
{
assert(data != NULL);
for (unsigned int i = 0U; i < 6U; i++) {
char c = data[i] >> 1;
if (c != ' ')
text += c;
}
unsigned char ssid = (data[6U] >> 1) & 0x0FU;
if (ssid > 0U) {
text += '-';
if (ssid >= 10U) {
text += '1';
text += '0' + ssid - 10U;
}
else {
text += '0' + ssid;
}
}
if (isDigi) {
if ((data[6U] & 0x80U) == 0x80U)
text += '*';
}
return (data[6U] & 0x01U) == 0x00U;
}