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Fix protection failure when calling select() on a file descriptor larger than FD_SETSIZE #114

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Fix protection failure when calling select() on a file descriptor larger than FD_SETSIZE #114

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1462da3
crash fix on windows 32-bit: DNSSD_API required for callbacks (define…
Apr 12, 2019
19f560c
Merge branch 'HBPVIS:master' into master
azeteg Jun 29, 2023
b5a235f
Fix invalid use of file descriptor for select() calls
azeteg Jun 29, 2023
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98 changes: 81 additions & 17 deletions servus/dnssd/servus.h
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Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,9 @@
#include <arpa/inet.h>
#include <sys/time.h>
#include <unistd.h>
#include <poll.h>
#else
#include <winsock2.h>
#endif
#include <dns_sd.h>

Expand All @@ -41,12 +44,35 @@ class Servus : public servus::Servus::Impl
, _in(0)
, _result(servus::Servus::Result::PENDING)
{
#ifdef _MSC_VER
if (WSAStartup(MAKEWORD(2, 2), &wsaData) != 0) {
const int error = WSAGetLastError();
char errorMessage[256] = {0};

FormatMessageA(
FORMAT_MESSAGE_FROM_SYSTEM,
NULL,
error,
MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
(LPSTR)errorMessage,
sizeof(errorMessage),
NULL
);

WARN << "WSAStartup error (" << error << "): " << errorMessage;

_result = servus::Servus::Result::POLL_ERROR;
}
#endif
}

virtual ~Servus()
{
withdraw();
endBrowsing();
#ifdef _MSC_VER
WSACleanup();
#endif
}

std::string getClassName() const { return "dnssd"; }
Expand Down Expand Up @@ -114,6 +140,9 @@ class Servus : public servus::Servus::Impl
DNSServiceRef _in; //!< used to browse()
int32_t _result;
std::string _browsedName;
#ifdef _MSC_VER
WSADATA wsaData;
#endif

servus::Servus::Result _browse(const ::servus::Servus::Interface addr)
{
Expand Down Expand Up @@ -160,41 +189,35 @@ class Servus : public servus::Servus::Impl
}
}

servus::Servus::Result _handleEvents(DNSServiceRef service,
const int32_t timeout = -1)
servus::Servus::Result _handleEvents(DNSServiceRef service, const int32_t timeout = -1)
{
assert(service);
if (!service)
return servus::Servus::Result(kDNSServiceErr_Unknown);

const int fd = DNSServiceRefSockFD(service);
const int nfds = fd + 1;

assert(fd >= 0);
if (fd < 0)
return servus::Servus::Result(kDNSServiceErr_BadParam);

#ifndef _MSC_VER
struct pollfd fds;
fds.fd = fd;
fds.events = POLLIN;

while (_result == servus::Servus::Result::PENDING)
{
fd_set fdSet;
FD_ZERO(&fdSet);
FD_SET(fd, &fdSet);

struct timeval tv;
tv.tv_sec = timeout / 1000;
tv.tv_usec = (timeout % 1000) * 1000;

const int result =
::select(nfds, &fdSet, 0, 0, timeout < 0 ? 0 : &tv);
const int result = poll(&fds, 1, timeout);
switch (result)
{
case 0: // timeout
_result = kDNSServiceErr_NoError;
break;

case -1: // error
WARN << "Select error: " << strerror(errno) << " (" << errno
<< ")" << std::endl;
WARN << "Poll error: " << strerror(errno) << " (" << errno
<< ")" << std::endl;
if (errno != EINTR)
{
withdraw();
Expand All @@ -203,23 +226,64 @@ class Servus : public servus::Servus::Impl
break;

default:
if (FD_ISSET(fd, &fdSet))
if (fds.revents & POLLIN)
{
const DNSServiceErrorType error =
DNSServiceProcessResult(service);

if (error != kDNSServiceErr_NoError)
{
WARN << "DNSServiceProcessResult error: " << error
<< std::endl;
<< std::endl;
withdraw();
_result = error;
}
}
break;
}
}
#else
WSAPOLLFD fds;
fds.fd = fd;
fds.events = POLLIN;

while (_result == servus::Servus::Result::PENDING)
{
const int result = WSAPoll(&fds, 1, timeout);
switch (result)
{
case 0: // timeout
_result = kDNSServiceErr_NoError;
break;

case -1: // error
WARN << "WSAPoll error: " << WSAGetLastError()
<< std::endl;
if (WSAGetLastError() != WSAEINTR)
{
withdraw();
_result = WSAGetLastError();
}
break;

default:
if (fds[0].revents & POLLIN)
{
const DNSServiceErrorType error =
DNSServiceProcessResult(service);

if (error != kDNSServiceErr_NoError)
{
WARN << "DNSServiceProcessResult error: " << error
<< std::endl;
withdraw();
_result = error;
}
}
break;
}
}
#endif
const servus::Servus::Result result(_result);
_result = servus::Servus::Result::PENDING; // reset for next operation
return result;
Expand Down