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Improvements to the error management of sockets. (#1081)
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@bcoconni
bcoconni committed May 8, 2024
1 parent 92ebcca commit 56c6662
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Showing 3 changed files with 194 additions and 68 deletions.
2 changes: 1 addition & 1 deletion src/input_output/FGInputSocket.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -243,7 +243,7 @@ void FGInputSocket::Read(bool Holding)
} else if (command == "quit") { // QUIT

// close the socket connection
socket->Reply("Closing connection\r\n");
socket->Send("Closing connection\r\n");
socket->Close();

} else if (command == "info") { // INFO
Expand Down
160 changes: 100 additions & 60 deletions src/input_output/FGfdmSocket.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -54,18 +54,20 @@ INCLUDES
#include <iostream>
#include <sstream>
#include <cstring>
#include <assert.h>
#include "FGfdmSocket.h"

using std::cout;
using std::cerr;
using std::endl;
using std::string;

// Defines that make BSD/Unix sockets and Windows sockets syntax look alike.
#ifndef _WIN32
// On BSD/Unix, defining the flags INVALID_SOCKET and SOCKET_ERROR to -1 allows
// using the same syntax for Windows and BSD/Unix platforms.
#define closesocket close
#define INVALID_SOCKET -1
#define SOCKET_ERROR -1
#define SD_BOTH SHUT_RDWR
#endif

namespace JSBSim {
Expand Down Expand Up @@ -208,6 +210,7 @@ FGfdmSocket::FGfdmSocket(int port, int protocol, int precision)

if (Protocol == ptTCP) {
if (listen(sckt, 5) != SOCKET_ERROR) { // successful listen()
connected = true;
#ifdef _WIN32
u_long NoBlock = 1;
ioctlsocket(sckt, FIONBIO, &NoBlock);
Expand All @@ -216,14 +219,19 @@ FGfdmSocket::FGfdmSocket(int port, int protocol, int precision)
fcntl(sckt, F_SETFL, flags | O_NONBLOCK);
#endif
sckt_in = accept(sckt, (struct sockaddr*)&scktName, &len);
connected = true;
} else
} else {
closesocket(sckt);
sckt = INVALID_SOCKET;
cerr << "Could not listen ..." << endl;
}
} else
connected = true;
} else // unsuccessful
cerr << "Could not bind to " << ProtocolName << " input socket, error = "
<< errno << endl;
} else { // unsuccessful
closesocket(sckt);
sckt = INVALID_SOCKET;
cerr << "Could not bind to " << ProtocolName << " input socket, error = "
<< errno << endl;
}
} else // unsuccessful
cerr << "Could not create " << ProtocolName << " socket for input, error = "
<< errno << endl;
Expand All @@ -235,8 +243,9 @@ FGfdmSocket::FGfdmSocket(int port, int protocol, int precision)

FGfdmSocket::~FGfdmSocket()
{
if (sckt != INVALID_SOCKET) shutdown(sckt,2);
if (sckt_in != INVALID_SOCKET) shutdown(sckt_in,2);
// Release the file descriptors to the OS.
if (sckt_in != INVALID_SOCKET) shutdown(sckt_in, SD_BOTH);
if (sckt != INVALID_SOCKET) closesocket(sckt);
Debug(1);
}

Expand All @@ -245,43 +254,48 @@ FGfdmSocket::~FGfdmSocket()
string FGfdmSocket::Receive(void)
{
char buf[1024];
socklen_t len = sizeof(struct sockaddr_in);
string data; // todo: should allocate this with a standard size as a
string data; // TODO should allocate this with a standard size as a
// class attribute and pass as a reference?

if (sckt_in == INVALID_SOCKET && Protocol == ptTCP) {
sckt_in = accept(sckt, (struct sockaddr*)&scktName, &len);
if (sckt_in != INVALID_SOCKET) {
if (Protocol == ptTCP){
if (sckt_in == INVALID_SOCKET) {
socklen_t len = sizeof(struct sockaddr_in);
sckt_in = accept(sckt, (struct sockaddr*)&scktName, &len);
if (sckt_in != INVALID_SOCKET) {
#ifdef _WIN32
u_long NoBlock = 1;
ioctlsocket(sckt_in, FIONBIO, &NoBlock);
u_long NoBlock = 1;
ioctlsocket(sckt_in, FIONBIO, &NoBlock);
#else
int flags = fcntl(sckt_in, F_GETFL, 0);
fcntl(sckt_in, F_SETFL, flags | O_NONBLOCK);
int flags = fcntl(sckt_in, F_GETFL, 0);
fcntl(sckt_in, F_SETFL, flags | O_NONBLOCK);
#endif
send(sckt_in, "Connected to JSBSim server\n\rJSBSim> ", 36, 0);
if (send(sckt_in, "Connected to JSBSim server\n\rJSBSim> ", 36, 0) == SOCKET_ERROR)
LogSocketError("Receive - TCP connection acknowledgement");
}
}
}

if (sckt_in != INVALID_SOCKET) {
int num_chars;
if (sckt_in != INVALID_SOCKET) {
int num_chars;

while ((num_chars = recv(sckt_in, buf, sizeof buf, 0)) > 0) {
data.append(buf, num_chars);
}
while ((num_chars = recv(sckt_in, buf, sizeof buf, 0)) > 0)
data.append(buf, num_chars);

if (num_chars == SOCKET_ERROR || num_chars == 0) {
#ifdef _WIN32
// when nothing received and the error isn't "would block"
// then assume that the client has closed the socket.
if (num_chars == 0) {
DWORD err = WSAGetLastError();
if (err != WSAEWOULDBLOCK) {
cout << "Socket Closed. Back to listening" << endl;
closesocket(sckt_in);
sckt_in = INVALID_SOCKET;
if (WSAGetLastError() != WSAEWOULDBLOCK)
#else
if (errno != EWOULDBLOCK)
#endif
{
LogSocketError("Receive - TCP data reception");
// when nothing received and the error isn't "would block"
// then assume that the client has closed the socket.
cout << "Socket Closed. Back to listening" << endl;
closesocket(sckt_in);
sckt_in = INVALID_SOCKET;
}
}
}
#endif
}

// this is for FGUDPInputSocket
Expand All @@ -290,6 +304,14 @@ string FGfdmSocket::Receive(void)
socklen_t fromlen = sizeof addr;
int num_chars = recvfrom(sckt, buf, sizeof buf, 0, (struct sockaddr*)&addr, &fromlen);
if (num_chars > 0) data.append(buf, num_chars);
if (num_chars == SOCKET_ERROR) {
#ifdef _WIN32
if (WSAGetLastError() != WSAEWOULDBLOCK)
#else
if (errno != EWOULDBLOCK)
#endif
LogSocketError("Receive - UDP data reception");
}
}

return data;
Expand All @@ -300,10 +322,12 @@ string FGfdmSocket::Receive(void)
int FGfdmSocket::Reply(const string& text)
{
int num_chars_sent=0;
assert(Protocol == ptTCP);

if (sckt_in != INVALID_SOCKET) {
num_chars_sent = send(sckt_in, text.c_str(), text.size(), 0);
send(sckt_in, "JSBSim> ", 8, 0);
if (num_chars_sent == SOCKET_ERROR) LogSocketError("Reply - Send data");
if (send(sckt_in, "JSBSim> ", 8, 0) == SOCKET_ERROR) LogSocketError("Reply - Prompt");
} else {
cerr << "Socket reply must be to a valid socket" << endl;
return -1;
Expand All @@ -315,19 +339,16 @@ int FGfdmSocket::Reply(const string& text)

void FGfdmSocket::Close(void)
{
#ifdef _WIN32
assert(Protocol == ptTCP);
closesocket(sckt_in);
#else
close(sckt_in);
#endif
sckt_in = INVALID_SOCKET;
sckt_in = INVALID_SOCKET;
}

//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

void FGfdmSocket::Clear(void)
{
buffer.str(string());
buffer.str("");
}

//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
Expand Down Expand Up @@ -368,45 +389,64 @@ void FGfdmSocket::Send(void)
{
buffer << '\n';
string str = buffer.str();
if ((send(sckt,str.c_str(),str.size(),0)) <= 0) {
perror("send");
}
Send(str.c_str(), str.size());
}

//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

void FGfdmSocket::Send(const char *data, int length)
{
if ((send(sckt,data,length,0)) <= 0) {
perror("send");
if (Protocol == ptTCP && sckt_in != INVALID_SOCKET) {
if ((send(sckt_in, data, length, 0)) == SOCKET_ERROR) LogSocketError("Send - TCP data sending");
return;
}

if (Protocol == ptUDP && sckt != INVALID_SOCKET) {
if ((send(sckt, data, length, 0)) == SOCKET_ERROR) LogSocketError("Send - UDP data sending");
return;
}

cerr << "Data sending must be to a valid socket" << endl;
}

//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

void FGfdmSocket::WaitUntilReadable(void)
{
if (sckt_in == INVALID_SOCKET)
return;
assert(Protocol == ptTCP);
if (sckt_in == INVALID_SOCKET) return;

fd_set fds;
FD_ZERO(&fds);
FD_SET(sckt_in, &fds);

int result = select(FD_SETSIZE, &fds, nullptr, nullptr, nullptr);

if (result == 0) {
cerr << "Socket timeout." << endl;
return;
} else if (result != SOCKET_ERROR)
return;

LogSocketError("WaitUntilReadable");
}

//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

void FGfdmSocket::LogSocketError(const std::string& msg)
{
// An error has occurred, display the error message.
cerr << "Socket error in " << msg << ": ";
#ifdef _WIN32
select(0, &fds, nullptr, nullptr, nullptr);
LPSTR errorMessage = nullptr;
DWORD errorCode = WSAGetLastError();
FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
nullptr, errorCode, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), (LPSTR)&errorMessage, 0, nullptr);
cerr << errorMessage << endl;
LocalFree(errorMessage);
#else
select(sckt_in+1, &fds, nullptr, nullptr, nullptr);
cerr << strerror(errno) << endl;
#endif

/*
If you want to check select return status:
int recVal = select(sckt_in+1, &fds, nullptr, nullptr, nullptr);
recVal: received value
0, if socket timeout
-1, if socket error
anithing else, if socket is readable
*/
}

//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
Expand Down
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