Use a mutex to allow the TAP reader to process packets faster on Windows.

The TAP-Win32 device is not a socket, and select() under Windows only works
with sockets.  Tinc used a separate thread to read from the TAP-Win32 device,
and passed this via a local socket to the main thread which could then select()
from it. We now use a global mutex, which is only unlocked when the main thread
is waiting for select(), to allow the TAP reader thread to process packets
directly.

diff --git a/src/mingw/device.c b/src/mingw/device.c
index e025cf7..fa13433 100644 (file)
--- a/src/mingw/device.c
+++ b/src/mingw/device.c
@@ -34,7 +34,7 @@
 
 #include "mingw/common.h"
 
-int device_fd = 0;
+int device_fd = -1;
 static HANDLE device_handle = INVALID_HANDLE_VALUE;
 char *device = NULL;
 char *iface = NULL;
@@ -45,63 +45,24 @@ static int device_total_out = 0;
 
 extern char *myport;
 
-static struct packetbuf {
-       uint8_t data[MTU];
-       length_t len;
-} *bufs;
-
-static int nbufs = 64;
-
 static DWORD WINAPI tapreader(void *bla) {
-       int sock, err, status;
-       struct addrinfo *ai;
-       struct addrinfo hint = {
-               .ai_family = AF_UNSPEC,
-               .ai_socktype = SOCK_STREAM,
-               .ai_protocol = IPPROTO_TCP,
-               .ai_flags = 0,
-       };
-       unsigned char bufno = 0;
+       int status;
        long len;
        OVERLAPPED overlapped;
-
-       /* Open a socket to the parent process */
-
-       err = getaddrinfo(NULL, myport, &hint, &ai);
-
-       if(err || !ai) {
-               logger(LOG_ERR, _("System call `%s' failed: %s"), "getaddrinfo", gai_strerror(errno));
-               return -1;
-       }
-
-       sock = socket(ai->ai_family, SOCK_STREAM, IPPROTO_TCP);
-
-       if(sock < 0) {
-               logger(LOG_ERR, _("System call `%s' failed: %s"), "socket", strerror(errno));
-               freeaddrinfo(ai);
-               return -1;
-       }
-
-       if(connect(sock, ai->ai_addr, ai->ai_addrlen)) {
-               logger(LOG_ERR, _("System call `%s' failed: %s"), "connect", strerror(errno));
-               freeaddrinfo(ai);
-               return -1;
-       }
-
-       freeaddrinfo(ai);
+       vpn_packet_t packet;
 
        logger(LOG_DEBUG, _("Tap reader running"));
 
        /* Read from tap device and send to parent */
 
        overlapped.hEvent = CreateEvent(NULL, TRUE, FALSE, NULL);
-       
+
        for(;;) {
                overlapped.Offset = 0;
                overlapped.OffsetHigh = 0;
                ResetEvent(overlapped.hEvent);
 
-               status = ReadFile(device_handle, bufs[bufno].data, MTU, &len, &overlapped);
+               status = ReadFile(device_handle, packet.data, MTU, &len, &overlapped);
 
                if(!status) {
                        if(GetLastError() == ERROR_IO_PENDING) {
@@ -115,11 +76,11 @@ static DWORD WINAPI tapreader(void *bla) {
                        }
                }
 
-               bufs[bufno].len = len;
-               if(send(sock, &bufno, 1, 0) <= 0)
-                       return -1;
-               if(++bufno >= nbufs)
-                       bufno = 0;
+               EnterCriticalSection(&mutex);
+               packet.len = len;
+               packet.priority = 0;
+               route(myself, &packet);
+               LeaveCriticalSection(&mutex);
        }
 }
 
@@ -240,44 +201,6 @@ bool setup_device(void)
                overwrite_mac = 1;
        }
 
-       /* Set up ringbuffer */
-
-       get_config_int(lookup_config(config_tree, "RingBufferSize"), &nbufs);
-       if(nbufs <= 1)
-               nbufs = 1;
-       else if(nbufs > 256)
-               nbufs = 256;
-       
-       bufs = xmalloc_and_zero(nbufs * sizeof *bufs);
-
-       /* Create a listening socket */
-
-       err = getaddrinfo(NULL, myport, &hint, &ai);
-
-       if(err || !ai) {
-               logger(LOG_ERR, _("System call `%s' failed: %s"), "getaddrinfo", gai_strerror(errno));
-               return false;
-       }
-
-       sock = socket(ai->ai_family, SOCK_STREAM, IPPROTO_TCP);
-
-       if(sock < 0) {
-               logger(LOG_ERR, _("System call `%s' failed: %s"), "socket", strerror(errno));
-               return false;
-       }
-
-       if(bind(sock, ai->ai_addr, ai->ai_addrlen)) {
-               logger(LOG_ERR, _("System call `%s' failed: %s"), "bind", strerror(errno));
-               return false;
-       }
-
-       freeaddrinfo(ai);
-
-       if(listen(sock, 1)) {
-               logger(LOG_ERR, _("System call `%s' failed: %s"), "listen", strerror(errno));
-               return false;
-       }
-
        /* Start the tap reader */
 
        thread = CreateThread(NULL, 0, tapreader, NULL, 0, NULL);
@@ -287,15 +210,6 @@ bool setup_device(void)
                return false;
        }
 
-       /* Wait for the tap reader to connect back to us */
-
-       if((device_fd = accept(sock, NULL, 0)) == -1) {
-               logger(LOG_ERR, _("System call `%s' failed: %s"), "accept", strerror(errno));
-               return false;
-       }
-
-       closesocket(sock);
-
        /* Set media status for newer TAP-Win32 devices */
 
        status = true;
@@ -320,25 +234,7 @@ void close_device(void)
 
 bool read_packet(vpn_packet_t *packet)
 {
-       unsigned char bufno;
-
-       cp();
-
-       if((recv(device_fd, &bufno, 1, 0)) <= 0) {
-               logger(LOG_ERR, _("Error while reading from %s %s: %s"), device_info,
-                          device, strerror(errno));
-               return false;
-       }
-       
-       packet->len = bufs[bufno].len;
-       memcpy(packet->data, bufs[bufno].data, bufs[bufno].len);
-
-       device_total_in += packet->len;
-
-       ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Read packet of %d bytes from %s"), packet->len,
-                          device_info);
-
-       return true;
+       return false;
 }
 
 bool write_packet(vpn_packet_t *packet)

diff --git a/src/net.c b/src/net.c
index c893f1e..82b0ede 100644 (file)
--- a/src/net.c
+++ b/src/net.c
@@ -149,7 +149,8 @@ static int build_fdset(fd_set *readset, fd_set *writeset)
                        max = listen_socket[i].udp;
        }
 
-       FD_SET(device_fd, readset);
+       if(device_fd >= 0)
+               FD_SET(device_fd, readset);
        if(device_fd > max)
                max = device_fd;
        
@@ -294,7 +295,7 @@ static void check_network_activity(fd_set * readset, fd_set * writeset)
        cp();
 
        /* check input from kernel */
-       if(FD_ISSET(device_fd, readset)) {
+       if(device_fd >= 0 && FD_ISSET(device_fd, readset)) {
                if(read_packet(&packet)) {
                        packet.priority = 0;
                        route(myself, &packet);
@@ -378,7 +379,13 @@ int main_loop(void)
 
                maxfd = build_fdset(&readset, &writeset);
 
+#ifdef HAVE_MINGW
+               LeaveCriticalSection(&mutex);
+#endif
                r = select(maxfd + 1, &readset, &writeset, NULL, &tv);
+#ifdef HAVE_MINGW
+               EnterCriticalSection(&mutex);
+#endif
 
                if(r < 0) {
                        if(errno != EINTR && errno != EAGAIN) {

diff --git a/src/net.h b/src/net.h
index 0f70a4b..ff32b73 100644 (file)
--- a/src/net.h
+++ b/src/net.h
@@ -143,6 +143,8 @@ extern void send_mtu_probe(struct node_t *);
 
 #ifndef HAVE_MINGW
 #define closesocket(s) close(s)
+#else
+extern CRITICAL_SECTION mutex;
 #endif
 
 #endif                                                 /* __TINC_NET_H__ */

diff --git a/src/tincd.c b/src/tincd.c
index a13e266..b2e055c 100644 (file)
--- a/src/tincd.c
+++ b/src/tincd.c
@@ -115,6 +115,7 @@ static struct option const long_options[] = {
 
 #ifdef HAVE_MINGW
 static struct WSAData wsa_state;
+CRITICAL_SECTION mutex;
 #endif
 
 static void usage(bool status)
@@ -568,6 +569,8 @@ int main(int argc, char **argv)
 
 int main2(int argc, char **argv)
 {
+       InitializeCriticalSection(&mutex);
+       EnterCriticalSection(&mutex);
 #endif
 
        if(!detach())