Don't use uninitialized value in MIN() for maxSocketsAllowed

CHANGELOG

@@ -1,5 +1,8 @@
 #Nmap Changelog ($Id$); -*-text-*-
 
+o Fixed an issue where TCP Connect scan (-sT) on Windows would fail to open any
+  sockets, leading to scans that never finish. [Daniel Miller]
+
 o [NSE] Fixed DNS TXT record parsing which caused asn-query to fail in Nmap
   7.80 and later. [David Fifield, Mike Pattrick]
 

scan_engine_connect.cc

@@ -87,11 +87,22 @@ ConnectScanInfo::ConnectScanInfo() {
   maxValidSD = -1;
   numSDs = 0;
   nextSD = -1;
-  if (o.max_parallelism > 0) {
+#ifndef WIN32
+  /* We can't issue a FD_SET operation with a socket descriptor greater than
+   * FD_SETSIZE, and we can't stop the OS from handing us ones that are greater
+   * than that, either, so leave a buffer here. */
+  maxSocketsAllowed = FD_SETSIZE - 10;
+#else
+  /* Windows does not have an explicit limit, but we have to keep it below
+   * FD_SETSIZE or select() will fail. Fortunately, it's about the *number* of
+   * sockets, not the socket descriptor number, so we can run right up to that
+   * limit. */
+  maxSocketsAllowed = FD_SETSIZE - 1;
+#endif
+  if (o.max_parallelism > 0 && o.max_parallelism < maxSocketsAllowed) {
     maxSocketsAllowed = o.max_parallelism;
   }
 #ifndef WIN32
-  else {
   /* Subtracting 10 from max_sd accounts for
      stdin
      stdout
@@ -103,21 +114,12 @@ ConnectScanInfo::ConnectScanInfo() {
      -oS log file
      -oX log file
      perhaps another we've forgotten. */
-    maxSocketsAllowed = max_sd() - 10;
+  int tmp_max_sd = max_sd() - 10;
-    if (maxSocketsAllowed < 5)
+  if (tmp_max_sd < 5)
-      maxSocketsAllowed = 5;
+    tmp_max_sd = 5;
-  }
+  maxSocketsAllowed = MIN(maxSocketsAllowed, tmp_max_sd);
-  /* We can't issue a FD_SET operation with a socket descriptor greater than
-   * FD_SETSIZE, and we can't stop the OS from handing us ones that are greater
-   * than that, either, so leave a buffer here. */
-  maxSocketsAllowed = MIN(maxSocketsAllowed, FD_SETSIZE - 10);
-#else
-  /* Windows does not have an explicit limit, but we have to keep it below
-   * FD_SETSIZE or select() will fail. Fortunately, it's about the *number* of
-   * sockets, not the socket descriptor number, so we can run right up to that
-   * limit. */
-  maxSocketsAllowed = MIN(maxSocketsAllowed, FD_SETSIZE - 1);
   #endif
+  assert(maxSocketsAllowed > 0);
   FD_ZERO(&fds_read);
   FD_ZERO(&fds_write);
   FD_ZERO(&fds_except);