issue with EGD in openssh

[Todd C. Miller]

There are a couple of issues regarding egd support in OpenSSH.

1) SIGPIPE is not ignored for the master listener daemon.  I put
   the signal() call early on since it needs to be before
   get_random_bytes() is called but it could also be placed in the
   EGD version of get_random_bytes().  For some reason, with prngd
   I am getting SIGPIPE even though the prngd processes is not
   dying.  get_random_bytes() also needs to check for EPIPE and
   reconnect to the daemon if it gets that.

2) If there are currently SOMAXCONN connections to the entropy
   daemon, further ones will return ECONNREFUSED.  It seems like
   some kind of connect || sleep loop is needed here.  I used
   usleep() which not all OSes support.  I've included the usleep.c
   from OpenBSD which uses nanosleep() but since not every OS has
   that either, a version using select() should probably be used
   when the OS has no nanosleep.  Also, the sleep is for only
   a total of 1 second before giving up.  Perhaps it should be longer.

I've included patches for these at the end of this message.

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#include "includes.h"

#ifndef HAVE_USLEEP

#if defined(LIBC_SCCS) && !defined(lint)
static char rcsid[] = "$OpenBSD: usleep.c,v 1.7 1998/02/08 22:44:09 tholo Exp $";
#endif /* LIBC_SCCS and not lint */

/* XXX - if no nanosleep() just use select */
int
usleep(useconds)
	unsigned int useconds;
{
	struct timespec rqt;

	if (useconds == 0)
		return(0);

	rqt.tv_sec = useconds / 1000000;
	rqt.tv_nsec = (useconds % 1000000) * 1000;

	return(nanosleep(&rqt, NULL));
}

#endif /* !HAVE_USLEEP */

--- sshd.c.DIST	Mon Feb 12 07:38:08 2001
+++ sshd.c	Mon Feb 12 07:36:18 2001
@@ -505,6 +505,9 @@
 	/* Initialize configuration options to their default values. */
 	initialize_server_options(&options);
 
+	/* Ignore SIGPIPE */
+	signal(SIGPIPE, SIG_IGN);
+
 	/* Parse command-line arguments. */
 	while ((opt = getopt(ac, av, "f:p:b:k:h:g:V:u:diqQ46")) != EOF) {
 		switch (opt) {
--- entropy.c.DIST	Mon Oct 16 03:13:43 2000
+++ entropy.c	Mon Feb 12 11:00:53 2001
@@ -69,6 +69,7 @@
 	char msg[2];
 	struct sockaddr_un addr;
 	int addr_len;
+	int i, rval;
 
 	/* Sanity checks */
 	if (sizeof(EGD_SOCKET) > sizeof(addr.sun_path))
@@ -81,13 +82,25 @@
 	strlcpy(addr.sun_path, EGD_SOCKET, sizeof(addr.sun_path));
 	addr_len = offsetof(struct sockaddr_un, sun_path) + sizeof(EGD_SOCKET);
 	
+reopen:
 	fd = socket(AF_UNIX, SOCK_STREAM, 0);
 	if (fd == -1) {
 		error("Couldn't create AF_UNIX socket: %s", strerror(errno));
 		return(0);
 	}
 
-	if (connect(fd, (struct sockaddr*)&addr, addr_len) == -1) {
+	/*
+	 * We may get ECONNREFUSED due to small SOMAXCONN in the daemon.
+	 * This will retry for at most one second (XXX - longer?)
+	 */
+	for (i = 0; i < 1000 &&
+	    (rval == connect(fd, (struct sockaddr*)&addr, addr_len)) == -1 &&
+	    errno == ECONNREFUSED;
+	    i++) {
+		usleep(1000);
+	}
+
+	if (rval == -1) {
 		error("Couldn't connect to EGD socket \"%s\": %s", 
 			addr.sun_path, strerror(errno));
 		close(fd);
@@ -99,6 +112,10 @@
 	msg[1] = len;
 
 	if (atomicio(write, fd, msg, sizeof(msg)) != sizeof(msg)) {
+		if (errno == EPIPE) {
+			close(fd);
+			goto reopen;
+		}
 		error("Couldn't write to EGD socket \"%s\": %s", 
 			EGD_SOCKET, strerror(errno));
 		close(fd);
@@ -106,6 +123,10 @@
 	}
 
 	if (atomicio(read, fd, buf, len) != len) {
+		if (errno == EPIPE) {
+			close(fd);
+			goto reopen;
+		}
 		error("Couldn't read from EGD socket \"%s\": %s", 
 			EGD_SOCKET, strerror(errno));
 		close(fd);