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net_io.c
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// Airspy1090, a Mode 1/2/3/A/C/S messages decoder for Airspy devices.
//
// Copyright (C) 2012 by Salvatore Sanfilippo <antirez@gmail.com>
// Copyright (C) 2021 by Malcolm Robb <support@attavionics.com>
//
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//
// * Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
#include "airspy1090.h"
//
// ============================= Networking =============================
//
// Note: here we disregard any kind of good coding practice in favor of
// extreme simplicity, that is:
//
// 1) We only rely on the kernel buffers for our I/O without any kind of
// user space buffering.
// 2) We don't register any kind of event handler, from time to time a
// function gets called and we accept new connections. All the rest is
// handled via non-blocking I/O and manually polling clients to see if
// they have something new to share with us when reading is needed.
//
//=========================================================================
//
// Networking "stack" initialization
//
typedef struct stService {
char *descr;
int *socket;
int port;
int enabled;
} tService;
tService services[MODES_NET_SERVICES_NUM];
void netInit(void) {
int j;
tService svc[MODES_NET_SERVICES_NUM] = {
{"AVR TCP output", &Modes.avrSocket, Modes.net_output_avr_port, 1},
{"RAW TCP output", &Modes.rawSocket, Modes.net_output_raw_port, 1},
{"Beast TCP output", &Modes.beastSocket, Modes.net_output_beast_port, 1},
{"Basestation TCP output", &Modes.sbsSocket, Modes.net_output_sbs_port, 1}
};
memcpy(&services, &svc, sizeof(svc));//services = svc;
Modes.clients = NULL;
#ifdef _WIN32
if ( (!Modes.wsaData.wVersion)
&& (!Modes.wsaData.wHighVersion) ) {
// Try to start the windows socket support
if (WSAStartup(MAKEWORD(2,1),&Modes.wsaData) != 0)
{
fprintf(stderr, "WSAStartup returned Error\n");
}
}
#endif
for (j = 0; j < MODES_NET_SERVICES_NUM; j++) {
services[j].enabled = (services[j].port != 0);
if (services[j].enabled) {
int s = anetTcpServer(Modes.aneterr, services[j].port, Modes.net_bind_address);
if (s == -1) {
fprintf(stderr, "Error opening the listening port %d (%s): %s\n",
services[j].port, services[j].descr, Modes.aneterr);
exit(1);
}
anetNonBlock(Modes.aneterr, s);
*services[j].socket = s;
}
}
#ifndef _WIN32
signal(SIGPIPE, SIG_IGN);
#endif
}
//
//=========================================================================
//
// This function gets called from time to time when the decoding thread is
// awakened by new data arriving. This usually happens a few times every second
//
tClient * netAcceptClients(void) {
int fd, port;
unsigned int j;
tClient *c;
for (j = 0; j < MODES_NET_SERVICES_NUM; j++) {
if (services[j].enabled) {
fd = anetTcpAccept(Modes.aneterr, *services[j].socket, NULL, &port);
if (fd == -1) continue;
anetNonBlock(Modes.aneterr, fd);
c = (tClient *) malloc(sizeof(*c));
if (!c) continue;
c->service = *services[j].socket;
c->next = Modes.clients;
c->fd = fd;
c->buflen = 0;
Modes.clients = c;
anetSetSendBuffer(Modes.aneterr,fd, (MODES_NET_SNDBUF_SIZE << Modes.net_sndbuf_size));
if (*services[j].socket == Modes.sbsSocket) Modes.sbsConnections++;
if (*services[j].socket == Modes.avrSocket) Modes.avrConnections++;
if (*services[j].socket == Modes.beastSocket) Modes.beastConnections++;
if (*services[j].socket == Modes.rawSocket) Modes.rawConnections++;
j--; // Try again with the same listening port
}
}
return Modes.clients;
}
//
//=========================================================================
//
// On error free the client, collect the structure, adjust maxfd if needed.
//
void netFreeClient(tClient *c) {
// Unhook this client from the linked list of clients
tClient *p = Modes.clients;
if (p) {
if (p == c) {
Modes.clients = c->next;
} else {
while ((p) && (p->next != c)) {
p = p->next;
}
if (p) {
p->next = c->next;
}
}
}
free(c);
}
//
//=========================================================================
//
// Close the client connection and mark it as closed
//
void netCloseClient(tClient *c) {
close(c->fd);
if (c->service == Modes.sbsSocket) {
if (Modes.sbsConnections) Modes.sbsConnections--;
} else if (c->service == Modes.avrSocket) {
if (Modes.avrConnections) Modes.avrConnections--;
} else if (c->service == Modes.beastSocket) {
if (Modes.beastConnections) Modes.beastConnections--;
} else if (c->service == Modes.rawSocket) {
if (Modes.rawConnections) Modes.rawConnections--;
}
c->fd = -1;
}
//
//=========================================================================
//
// Send the specified message to all clients listening for a given service
//
void netSendAllClients(int service, void *msg, int len) {
tClient *c = Modes.clients;
while (c) {
// Read next before servicing client incase the service routine deletes the client!
tClient *next = c->next;
if (c->fd != -1) {
if (c->service == service) {
#ifndef _WIN32
int nwritten = write(c->fd, msg, len);
#else
int nwritten = send(c->fd, msg, len, 0 );
#endif
if (nwritten != len) {
netCloseClient(c);
}
}
} else {
netFreeClient(c);
}
c = next;
}
}
//
//=========================================================================
//
// Write raw output in Beast Binary format with Timestamp to TCP clients
//
void netSendBeastOutput(tModesMessage *mm) {
char *p = &Modes.beastOut[Modes.beastOutUsed];
int msgLen = mm->rm.uMsgBits / 8;
uint64_t lTimeStamp = mm->rm.lTime;
char ch;
int j;
int iOutLen = msgLen + 9; // Escape, msgtype, timestamp, sigLevel, msg
// Output the escape character
*p++ = 0x1a;
// Output the message type, and correct the timestamp for message type
if (msgLen == MODES_SHORT_MSG_BYTES)
{*p++ = '2';}
else if (msgLen == MODES_LONG_MSG_BYTES)
{*p++ = '3';}
else if (msgLen == MODEAC_MSG_BYTES)
{*p++ = '1'; lTimeStamp += (377 * 20);}
else
{return;}
// Output the Timestamp
*p++ = (ch = (unsigned char)((lTimeStamp >> 40) & 0xFF));
if (0x1A == ch) { *p++ = ch; iOutLen++; }
*p++ = (ch = (unsigned char)((lTimeStamp >> 32) & 0xFF));
if (0x1A == ch) { *p++ = ch; iOutLen++; }
*p++ = (ch = (unsigned char)((lTimeStamp >> 24) & 0xFF));
if (0x1A == ch) { *p++ = ch; iOutLen++; }
*p++ = (ch = (unsigned char)((lTimeStamp >> 16) & 0xFF));
if (0x1A == ch) { *p++ = ch; iOutLen++; }
*p++ = (ch = (unsigned char)((lTimeStamp >> 8) & 0xFF));
if (0x1A == ch) { *p++ = ch; iOutLen++; }
*p++ = (ch = (unsigned char)((lTimeStamp >> 0) & 0xFF));
if (0x1A == ch) { *p++ = ch; iOutLen++; }
// Output the signal level
*p++ = (ch = mm->signalLevel);
if (0x1A == ch) {*p++ = ch; iOutLen++;}
// Output the message bytes
for (j = 0; j < msgLen; j++) {
*p++ = (ch = mm->rm.ucMsg[j]);
if (0x1A == ch) {*p++ = ch; iOutLen++;}
}
// Increase the Beast buffer count to include this message
Modes.beastOutUsed += iOutLen;
// If the buffer now contains enough data to be worth sending, send it
if (Modes.beastOutUsed >= Modes.net_output_raw_size) {
netSendAllClients(Modes.beastSocket, Modes.beastOut, Modes.beastOutUsed);
Modes.beastOutUsed = 0;
Modes.net_output_raw_rate_count = 0;
}
}
//
//=========================================================================
//
// Write RAW ASCII output (with timestamp) to TCP clients
//
void netSendRawOutput(tModesMessage *mm) {
char *p = &Modes.rawOut[Modes.rawOutUsed];
int msgLen = mm->rm.uMsgBits / 8;
int j;
unsigned char * pTimeStamp;
*p++ = '@';
pTimeStamp = (unsigned char *) &mm->rm.lTime;
for (j = 5; j >= 0; j--) {
sprintf(p, "%02X", pTimeStamp[j]);
p += 2;
}
Modes.rawOutUsed += 12; // additional 12 characters for timestamp
for (j = 0; j < msgLen; j++) {
sprintf(p, "%02X", mm->rm.ucMsg[j]);
p += 2;
}
*p++ = ';';
*p++ = '\n';
Modes.rawOutUsed += ((msgLen*2) + 3);
if (Modes.rawOutUsed >= Modes.net_output_raw_size) {
netSendAllClients(Modes.rawSocket, Modes.rawOut, Modes.rawOutUsed);
Modes.rawOutUsed = 0;
Modes.net_output_raw_rate_count = 0;
}
}
//
//=========================================================================
//
// Write AVR ASCII (no timestamp) output to TCP clients
//
void netSendAVROutput(tModesMessage *mm) {
char *p = &Modes.avrOut[Modes.avrOutUsed];
int msgLen = mm->rm.uMsgBits / 8;
int j;
*p++ = '*';
for (j = 0; j < msgLen; j++) {
sprintf(p, "%02X", mm->rm.ucMsg[j]);
p += 2;
}
*p++ = ';';
*p++ = '\n';
Modes.avrOutUsed += ((msgLen*2) + 3);
if (Modes.avrOutUsed >= Modes.net_output_raw_size) {
netSendAllClients(Modes.avrSocket, Modes.avrOut, Modes.avrOutUsed);
Modes.avrOutUsed = 0;
Modes.net_output_raw_rate_count = 0;
}
}
//
//=========================================================================
//
// Write SBS output to TCP clients
// The message structure mm->bFlags tells us what has been updated by this message
//
void netSendSBSOutput(tModesMessage *mm) {
char msg[256], *p = msg;
uint32_t offset;
struct timeb epocTime_receive, epocTime_now;
struct tm stTime_receive, stTime_now;
int msgType;
//
// SBS BS style output checked against the following reference
// http://www.homepages.mcb.net/bones/SBS/Article/Barebones42_Socket_Data.htm - seems comprehensive
//
// Decide on the basic SBS Message Type
if ((mm->rm.uMsgType == 4) || (mm->rm.uMsgType == 20)) {
msgType = 5;
} else if ((mm->rm.uMsgType == 5) || (mm->rm.uMsgType == 21)) {
msgType = 6;
} else if ((mm->rm.uMsgType == 0) || (mm->rm.uMsgType == 16)) {
msgType = 7;
} else if (mm->rm.uMsgType == 11) {
msgType = 8;
} else if ((mm->rm.uMsgType != 17) && (mm->rm.uMsgType != 18)) {
return;
} else if ((mm->metype >= 1) && (mm->metype <= 4)) {
msgType = 1;
} else if ((mm->metype >= 5) && (mm->metype <= 8)) {
if (mm->bFlags & MODES_ACFLAGS_LATLON_VALID)
{msgType = 2;}
else
{msgType = 7;}
} else if ((mm->metype >= 9) && (mm->metype <= 18)) {
if (mm->bFlags & MODES_ACFLAGS_LATLON_VALID)
{msgType = 3;}
else
{msgType = 7;}
} else if (mm->metype != 19) {
return;
} else if ((mm->mesub == 1) || (mm->mesub == 2)) {
msgType = 4;
} else {
return;
}
// Fields 1 to 6 : SBS message type and ICAO address of the aircraft and some other stuff
p += sprintf(p, "MSG,%d,111,11111,%06X,111111,", msgType, mm->rm.uAddr);
// Find current system time
ftime(&epocTime_now); // get the current system time & date
stTime_now = *localtime(&epocTime_now.time);
// Find message reception time
if (mm->rm.lTime) { // Make sure the records' timestamp is valid before using it
epocTime_receive = Modes.stSystemTimeBlk; // This is the time of the start of the Block we're processing
offset = (int) (mm->rm.lTime - Modes.timestampBlk); // This is the time (in 12Mhz ticks) into the Block
offset = offset / 12000; // convert to milliseconds
epocTime_receive.millitm += (uint16_t) offset; // add on the offset time to the Block start time
if (epocTime_receive.millitm > 999) { // if we've caused an overflow into the next second...
epocTime_receive.millitm -= 1000;
epocTime_receive.time ++; // ..correct the overflow
}
stTime_receive = *localtime(&epocTime_receive.time);
} else {
epocTime_receive = epocTime_now; // We don't have a usable reception time; use the current system time
stTime_receive = stTime_now;
}
// Fields 7 & 8 are the message reception time and date
p += sprintf(p, "%04d/%02d/%02d,", (stTime_receive.tm_year+1900),(stTime_receive.tm_mon+1), stTime_receive.tm_mday);
p += sprintf(p, "%02d:%02d:%02d.%03d,", stTime_receive.tm_hour, stTime_receive.tm_min, stTime_receive.tm_sec, epocTime_receive.millitm);
// Fields 9 & 10 are the current time and date
p += sprintf(p, "%04d/%02d/%02d,", (stTime_now.tm_year+1900),(stTime_now.tm_mon+1), stTime_now.tm_mday);
p += sprintf(p, "%02d:%02d:%02d.%03d", stTime_now.tm_hour, stTime_now.tm_min, stTime_now.tm_sec, epocTime_now.millitm);
// Field 11 is the callsign (if we have it)
if (mm->bFlags & MODES_ACFLAGS_CALLSIGN_VALID) {p += sprintf(p, ",%s", mm->flight);}
else {p += sprintf(p, ",");}
// Field 12 is the altitude (if we have it) - force to zero if we're on the ground
if ((mm->bFlags & MODES_ACFLAGS_AOG_GROUND) == MODES_ACFLAGS_AOG_GROUND) {
p += sprintf(p, ",0");
} else if (mm->bFlags & MODES_ACFLAGS_ALTITUDE_VALID) {
p += sprintf(p, ",%d", mm->altitude);
} else {
p += sprintf(p, ",");
}
// Field 13 is the ground Speed (if we have it)
if (mm->bFlags & MODES_ACFLAGS_SPEED_VALID) {
p += sprintf(p, ",%d", mm->velocity);
} else {
p += sprintf(p, ",");
}
// Field 14 is the ground Heading (if we have it)
if (mm->bFlags & MODES_ACFLAGS_HEADING_VALID) {
p += sprintf(p, ",%d", mm->heading);
} else {
p += sprintf(p, ",");
}
// Fields 15 and 16 are the Lat/Lon (if we have it)
if (mm->bFlags & MODES_ACFLAGS_LATLON_VALID) {p += sprintf(p, ",%1.5f,%1.5f", mm->fLat, mm->fLon);}
else {p += sprintf(p, ",,");}
// Field 17 is the VerticalRate (if we have it)
if (mm->bFlags & MODES_ACFLAGS_VERTRATE_VALID) {p += sprintf(p, ",%d", mm->vert_rate);}
else {p += sprintf(p, ",");}
// Field 18 is the Squawk (if we have it)
if (mm->bFlags & MODES_ACFLAGS_SQUAWK_VALID) {p += sprintf(p, ",%x", mm->uModeA);}
else {p += sprintf(p, ",");}
// Field 19 is the Squawk Changing Alert flag (if we have it)
if (mm->bFlags & MODES_ACFLAGS_FS_VALID) {
if ((mm->fs >= 2) && (mm->fs <= 4)) {
p += sprintf(p, ",-1");
} else {
p += sprintf(p, ",0");
}
} else {
p += sprintf(p, ",");
}
// Field 20 is the Squawk Emergency flag (if we have it)
if (mm->bFlags & MODES_ACFLAGS_SQUAWK_VALID) {
if ((mm->uModeA == 0x7500) || (mm->uModeA == 0x7600) || (mm->uModeA == 0x7700)) {
p += sprintf(p, ",-1");
} else {
p += sprintf(p, ",0");
}
} else {
p += sprintf(p, ",");
}
// Field 21 is the Squawk Ident flag (if we have it)
if (mm->bFlags & MODES_ACFLAGS_FS_VALID) {
if ((mm->fs >= 4) && (mm->fs <= 5)) {
p += sprintf(p, ",-1");
} else {
p += sprintf(p, ",0");
}
} else {
p += sprintf(p, ",");
}
// Field 22 is the OnTheGround flag (if we have it)
if (mm->bFlags & MODES_ACFLAGS_AOG_VALID) {
if (mm->bFlags & MODES_ACFLAGS_AOG) {
p += sprintf(p, ",-1");
} else {
p += sprintf(p, ",0");
}
} else {
p += sprintf(p, ",");
}
p += sprintf(p, "\r\n");
netSendAllClients(Modes.sbsSocket, msg, (int) (p-msg));
}
//
//=========================================================================
//
void netQueueOutput(tModesMessage *mm) {
if (Modes.sbsConnections) {netSendSBSOutput(mm);}
if (Modes.beastConnections) {netSendBeastOutput(mm);}
if (Modes.rawConnections) {netSendRawOutput(mm);}
if (Modes.avrConnections) {netSendAVROutput(mm);}
}
//
//=========================================================================
//
// Read data from clients. This function actually delegates a lower-level
// function that depends on the kind of service (raw, http, ...).
//
void netReadFromClients(void) {
tClient *c = netAcceptClients();
while (c) {
// Read next before servicing client incase the service routine deletes the client!
tClient *next = c->next;
if (c->fd < 0) {
netFreeClient(c);
}
c = next;
}
}
//
//=========================================================================
//
void netFlushClients(uint64_t lTime) {
//Send any remaining partial raw buffers now
if (Modes.avrOutUsed || Modes.beastOutUsed || Modes.rawOutUsed) {
Modes.net_output_raw_rate_count++;
if (Modes.net_output_raw_rate_count > Modes.net_output_raw_rate) {
if (Modes.avrOutUsed) {
netSendAllClients(Modes.avrSocket, Modes.avrOut, Modes.avrOutUsed);
Modes.avrOutUsed = 0;
}
if (Modes.rawOutUsed) {
netSendAllClients(Modes.rawSocket, Modes.rawOut, Modes.rawOutUsed);
Modes.rawOutUsed = 0;
}
if (Modes.beastOutUsed) {
netSendAllClients(Modes.beastSocket, Modes.beastOut, Modes.beastOutUsed);
Modes.beastOutUsed = 0;
}
Modes.net_output_raw_rate_count = 0;
}
}
// Nothing to send, so increase the heartbeat
else if ((Modes.net_heartbeat_rate)
&& ((++Modes.net_heartbeat_count) > Modes.net_heartbeat_rate)) {
//
// We haven't received any Mode A/C/S messages for some time. To try and keep any TCP
// links alive, send a null frame. This will help stop any routers discarding our TCP
// link which will cause an un-recoverable link error if/when a real frame arrives.
//
// Fudge up a null message
tModesMessage mm;
memset(&mm, 0, sizeof(mm));
mm.rm.uMsgBits = MODES_SHORT_MSG_BITS;
mm.rm.lTime = lTime;
// Feed output clients
netQueueOutput(&mm);
// Reset the heartbeat counter
Modes.net_heartbeat_count = 0;
}
}
//
// =============================== Network IO ===========================
//