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SO_SNDTIMEO and SO_RCVTIMEO socket options have turned out not to be reliable.

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Use select() for detecting timeout on socket (read and write).
This commit is contained in:
Gerhard Hoffmann
2023-08-14 14:35:54 +02:00
parent 66d0214720
commit 8d528f0f55
1 changed files with 108 additions and 38 deletions
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146
ismas/ismas_client.cpp
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@@ -137,7 +137,12 @@ IsmasClient::sendRequestReceiveResponse(int port, QString const &request) {
so_linger.l_onoff = 1;
so_linger.l_linger = 0;
int maxfdp1;
fd_set rset;
fd_set wset;
setsockopt(sockfd, SOL_SOCKET, SO_LINGER, &so_linger, sizeof(so_linger));
// no reliable, but does not harm, as we use select() as well
setsockopt(sockfd, SOL_SOCKET, SO_SNDTIMEO, &tv, sizeof(tv));
setsockopt(sockfd, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv));
int flag = 1;
@@ -151,24 +156,56 @@ IsmasClient::sendRequestReceiveResponse(int port, QString const &request) {
int loop = 0;
int bytesWritten = 0;
while (bytesWritten < bytesToWrite) {
int n = ::sendto(sockfd, buf+bytesWritten, bytesToWrite-bytesWritten, 0, NULL, 0);
if (n >= 0) {
bytesWritten += n;
} else {
if (errno == EWOULDBLOCK) {
if (++loop < 10) {
QThread::msleep(500);
continue;
}
printErrorMessage(port, clientIP, clientPort,
QString("WRITE TIMEOUT %1(").arg(loop) + strerror(errno) + ")");
::close(sockfd);
return std::nullopt;
} else
errno = 0;
FD_ZERO(&wset);
FD_SET(sockfd, &wset);
maxfdp1 = sockfd + 1;
tv.tv_sec = 60; /* 60 secs timeout for read and write -> APISM cuts the connection after 30s */
tv.tv_usec = 0;
int const w = select(maxfdp1, NULL, &wset, NULL, &tv);
if (w < 0) { // error
if (errno == EINTR) {
printErrorMessage(port, clientIP, clientPort,
QString("WRITE INTERRUPTED BY SIGNAL (1) (") + strerror(errno) + ")");
QString("INTERRUPTED BY SIGNAL (1) (") + strerror(errno) + ")");
continue;
} else {
printErrorMessage(port, clientIP, clientPort,
QString("SELECT-ERROR (WRITE) %1(").arg(loop) + strerror(errno) + ")");
::close(sockfd);
return std::nullopt;
}
} else
if (w == 0) { // timeout
printErrorMessage(port, clientIP, clientPort,
QString("SELECT-TIMEOUT (WRITE) %1(").arg(loop) + strerror(errno) + ")");
if (++loop < 10) {
QThread::msleep(500);
continue;
}
::close(sockfd);
return std::nullopt;
} else
if (w > 0) {
int n = ::sendto(sockfd, buf+bytesWritten, bytesToWrite-bytesWritten, 0, NULL, 0);
if (n >= 0) {
bytesWritten += n;
} else {
if (errno == EWOULDBLOCK) {
if (++loop < 10) {
QThread::msleep(500);
continue;
}
printErrorMessage(port, clientIP, clientPort,
QString("WRITE TIMEOUT %1(").arg(loop) + strerror(errno) + ")");
::close(sockfd);
return std::nullopt;
} else
if (errno == EINTR) {
printErrorMessage(port, clientIP, clientPort,
QString("WRITE INTERRUPTED BY SIGNAL (1) (") + strerror(errno) + ")");
continue;
}
}
}
}
@@ -188,33 +225,66 @@ IsmasClient::sendRequestReceiveResponse(int port, QString const &request) {
int bytesRead = 0;
while (bytesRead < bytesToRead) {
errno = 0;
int n = ::recvfrom(sockfd, buf+bytesRead, bytesToRead-bytesRead,
0, NULL, NULL);
if (n > 0) { //
bytesRead += n;
} else
if (n == 0) {
// The return value will be 0 when the peer has performed an orderly shutdown.
printErrorMessage(port, clientIP, clientPort,
QString("PEER CLOSED CONNECTION (") + strerror(errno) + ")");
::close(sockfd);
return std::nullopt;
} else
if (n < 0) {
if (errno == EWOULDBLOCK) {
if (++loop < 10) {
QThread::msleep(500);
continue;
}
printErrorMessage(port, clientIP, clientPort,
QString("READ TIMEOUT %1(").arg(loop) + strerror(errno) + ")");
::close(sockfd);
return std::nullopt;
}
FD_ZERO(&rset);
FD_SET(sockfd, &rset);
maxfdp1 = sockfd + 1;
tv.tv_sec = 60; /* 60 secs timeout for read and write */
tv.tv_usec = 0;
int const r = select(maxfdp1, &rset, NULL, NULL, &tv);
if (r < 0) { // error
if (errno == EINTR) {
printErrorMessage(port, clientIP, clientPort,
QString("INTERRUPTED BY SIGNAL (2) (") + strerror(errno) + ")");
continue;
} else {
printErrorMessage(port, clientIP, clientPort,
QString("SELECT-ERROR (READ) %1(").arg(loop) + strerror(errno) + ")");
::close(sockfd);
return std::nullopt;
}
} else
if (r == 0) { // timeout
printErrorMessage(port, clientIP, clientPort,
QString("SELECT-TIMEOUT (READ) %1(").arg(loop) + strerror(errno) + ")");
if (++loop < 10) {
QThread::msleep(500);
continue;
}
::close(sockfd);
return std::nullopt;
} else
if (r > 0) {
if (FD_ISSET(sockfd, &rset)) {
int n = ::recvfrom(sockfd, buf+bytesRead, bytesToRead-bytesRead,
0, NULL, NULL);
if (n > 0) { //
bytesRead += n;
} else
if (n == 0) {
// The return value will be 0 when the peer has performed an orderly shutdown.
printErrorMessage(port, clientIP, clientPort,
QString("PEER CLOSED CONNECTION (") + strerror(errno) + ")");
::close(sockfd);
return std::nullopt;
} else
if (n < 0) {
if (errno == EWOULDBLOCK) { // check just in case
if (++loop < 10) {
QThread::msleep(500);
continue;
}
printErrorMessage(port, clientIP, clientPort,
QString("READ TIMEOUT %1(").arg(loop) + strerror(errno) + ")");
::close(sockfd);
return std::nullopt;
}
if (errno == EINTR) {
printErrorMessage(port, clientIP, clientPort,
QString("INTERRUPTED BY SIGNAL (2) (") + strerror(errno) + ")");
continue;
}
}
}
}