Report error when file descriptor number is too large for select() in…

… socket

code or when there are too many descriptors (PR#18634).


git-svn-id: https://svn.r-project.org/R/trunk@85689 00db46b3-68df-0310-9c12-caf00c1e9a41

src/main/connections.c

@@ -87,6 +87,18 @@
 
   Using a dynamic upper limit would not be hard, but not very useful
   because of the non-dynamic fd limit.
+
+  The current implementation of socket connections uses select(). On
+  POSIX systems, only FD_SETSIZE descriptors are supported and they 
+  must have numbers between 0 and FD_SETSIZE-1, inclusive. On Linux and macOS,
+  FD_SETSIZE is normally 1024. On macOS, the limit could be overcome via
+  _DARWIN_UNLIMITED_SELECT (not used by R), but a POSIX solution would
+  be to use poll() instead of select(). On Windows, by default 1024 different
+  descriptors are supported in a single select() call, but these include
+  valid socket file descriptors of arbitrary numbers, much larger
+  than FD_SETSIZE.  On Windows, the limit can be set in the program
+  by setting FD_SETSIZE before including WinSock headers, R sets it to
+  1024 (in sock.h and here in connections.c).
 */
 
 #ifdef HAVE_CONFIG_H
@@ -6323,6 +6335,13 @@ attribute_hidden SEXP do_sockselect(SEXP call, SEXP op, SEXP args, SEXP rho)
     int nsock, i;
     SEXP insock, write, val, insockfd;
     double timeout;
+    int fdlim;
+
+#ifdef Win32
+    fdlim = 1024; /* keep in step with sock.h */
+#else
+    fdlim = FD_SETSIZE;
+#endif
 
     checkArity(op, args);
 
@@ -6358,8 +6377,16 @@ attribute_hidden SEXP do_sockselect(SEXP call, SEXP op, SEXP args, SEXP rho)
 		warning(_("a server socket connection cannot be writeable"));
 	} else
 	    error(_("not a socket connection"));
+#ifdef Unix
+	if (INTEGER(insockfd)[i] >= fdlim && !immediate)
+	    error(_("file descriptor is too large for select()"));
+#endif
     }
 
+#ifdef Win32
+    if (nsock > fdlim && !immediate)
+	error(_("too many file descriptors for select()"));
+#endif
     if (! immediate)
 	Rsockselect(nsock, INTEGER(insockfd), LOGICAL(val), LOGICAL(write),
 		    timeout);

src/modules/internet/Rsock.c

@@ -1,7 +1,7 @@
 /*
  *  R : A Computer Language for Statistical Data Analysis
 
- *  Copyright (C) 1998-2021   The R Core Team
+ *  Copyright (C) 1998-2023   The R Core Team
  *  Copyright (C) 1996, 1997  Robert Gentleman and Ross Ihaka
  *
  *  This program is free software; you can redistribute it and/or modify
@@ -196,6 +196,7 @@ setSelectMask(InputHandler *handlers, fd_set *readMask)
 
     while(tmp) {
 	if(tmp->fileDescriptor > 0) {
+	    /* FD_SETSIZE limit checked by addInputHandler */
 	    FD_SET(tmp->fileDescriptor, readMask);
 	    maxfd = maxfd < tmp->fileDescriptor ? tmp->fileDescriptor : maxfd;
 	}
@@ -237,6 +238,8 @@ static int R_SocketWait(int sockfd, int write, int timeout)
 	set_timeval(&tv, timeout);
 
 #ifdef Unix
+	if (sockfd >= FD_SETSIZE)
+	    return -EINVAL;
 	maxfd = setSelectMask(R_InputHandlers, &rfd);
 #else
 	FD_ZERO(&rfd);
@@ -324,7 +327,15 @@ int R_SocketWaitMultiple(int nsock, int *insockfd, int *ready, int *write,
 	FD_ZERO(&rfd);
 #endif
 	FD_ZERO(&wfd);
+#ifdef Win32
+	if (nsock > FD_SETSIZE)
+	    return -WSAEINVAL;
+#endif
 	for (i = 0; i < nsock; i++) {
+#ifdef Unix
+	    if (insockfd[i] >= FD_SETSIZE)
+		return -EINVAL;
+#endif
 	    if(write[i]) FD_SET(insockfd[i], &wfd);
 	    else FD_SET(insockfd[i], &rfd);
 	    if(maxfd < insockfd[i]) maxfd = insockfd[i];
@@ -432,6 +443,10 @@ int R_SockConnect(int port, char *host, int timeout)
 	set_timeval(&tv, timeout);
 
 #ifdef Unix
+	if (s >= FD_SETSIZE) {
+	    errno = EINVAL;
+	    CLOSE_N_RETURN(-1);
+	}
 	maxfd = setSelectMask(R_InputHandlers, &rfd);
 #else
 	FD_ZERO(&rfd);
@@ -567,6 +582,10 @@ int R_SockListen(int sockp, char *buf, int len, int timeout)
 	set_timeval(&tv, timeout);
 
 #ifdef Unix
+	if (sockp >= FD_SETSIZE) {
+	    errno = EINVAL;
+	    return -1;
+	}
 	maxfd = setSelectMask(R_InputHandlers, &rfd);
 #else
 	FD_ZERO(&rfd);

src/modules/internet/sock.h

@@ -1,7 +1,7 @@
 /*
  *  R : A Computer Language for Statistical Data Analysis
 
- *  Copyright (C) 1998-2020   The R Core Team
+ *  Copyright (C) 1998-2023   The R Core Team
  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
@@ -42,6 +42,7 @@ ssize_t Sock_write(int fd, const void *buf, size_t nbytes, Sock_error_t perr);
 #ifndef Win32
 # define SOCKET int
 #else
+  /* keep FD_SETSIZE in step with connections.c, but this is the default */
 # define FD_SETSIZE 1024
 # include<winsock2.h>
 #endif

src/modules/internet/sockconn.c

@@ -1,6 +1,6 @@
 /*
  *  R : A Computer Language for Statistical Data Analysis
- *  Copyright (C)  2001-2022   The R Core Team.
+ *  Copyright (C)  2001-2023   The R Core Team.
  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
@@ -55,6 +55,14 @@ static Rboolean sock_open(Rconnection con)
 		warning("port %d cannot be opened", this->port);
 		return FALSE;
 	    }
+#ifdef Unix
+	    if (sock1 >= FD_SETSIZE) {
+		/* R_SockListen below would fail */
+		R_SockClose(sock1);
+		warning(_("file descriptor is too large for select()"));
+		return FALSE;
+	    }
+#endif
 	    {
 		RCNTXT cntxt;
 
@@ -81,6 +89,14 @@ static Rboolean sock_open(Rconnection con)
 		return FALSE;
 	    }
 	}
+#ifdef Unix
+	if (sock >= FD_SETSIZE && (con->canwrite || con->blocking)) {
+	    /* Reading/writing via such socket would fail */
+	    R_SockClose(sock);
+	    warning(_("file descriptor is too large for select()"));
+	    return FALSE;
+	}
+#endif
 	free(con->description);
 	size_t sz = strlen(buf) + 10;
 	con->description = (char *) malloc(sz); // FIXME check allocation 
@@ -272,6 +288,15 @@ Rconnection in_R_newservsock(int port)
 	      port);
 	/* for Solaris 12.5 */ new = NULL;
     }
+#ifdef Unix
+    if (sock >= FD_SETSIZE) {
+	/* R_SockListen (accept) called from sock_open would fail */
+	free(new->private); free(new->description); free(new->class); free(new);
+	R_SockClose(sock);
+	error(_("file descriptor is too large for select()"));
+	/* for Solaris 12.5 */ new = NULL;
+    }
+#endif
     ((Rservsockconn)new->private)-> fd = sock;
     new->isopen = TRUE;