upstream: Wait for FD to be readable or writeable during a nonblocking

connect, not just readable.  Prevents a timeout when the server doesn't
immediately send a banner (eg multiplexers like sslh) but is also slightly
quicker for other connections since, unlike ssh1, ssh2 doesn't specify
that the client should parse the server banner before sending its own.
Patch from mnissler@chromium.org, ok djm@

OpenBSD-Commit-ID: aba9cd8480d1d9dd31d0ca0422ea155c26c5df1d

1 files changed, 16 insertions, 6 deletions

diff --git a/misc.c b/misc.c
index 78c00eb8e..5204c1e9f 100644
--- a/misc.c
+++ b/misc.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: misc.c,v 1.142 2019/09/03 08:32:11 djm Exp $ */
+/* $OpenBSD: misc.c,v 1.143 2019/11/22 06:50:30 dtucker Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  * Copyright (c) 2005,2006 Damien Miller.  All rights reserved.
@@ -238,12 +238,12 @@ set_rdomain(int fd, const char *name)
 }
 
 /*
- * Wait up to *timeoutp milliseconds for fd to be readable. Updates
+ * Wait up to *timeoutp milliseconds for events on fd. Updates
  * *timeoutp with time remaining.
  * Returns 0 if fd ready or -1 on timeout or error (see errno).
  */
-int
-waitrfd(int fd, int *timeoutp)
+static int
+waitfd(int fd, int *timeoutp, short events)
 {
         struct pollfd pfd;
         struct timeval t_start;
@@ -251,7 +251,7 @@ waitrfd(int fd, int *timeoutp)
 
         monotime_tv(&t_start);
         pfd.fd = fd;
-        pfd.events = POLLIN;
+        pfd.events = events;
         for (; *timeoutp >= 0;) {
                 r = poll(&pfd, 1, *timeoutp);
                 oerrno = errno;
@@ -270,6 +270,16 @@ waitrfd(int fd, int *timeoutp)
 }
 
 /*
+ * Wait up to *timeoutp milliseconds for fd to be readable. Updates
+ * *timeoutp with time remaining.
+ * Returns 0 if fd ready or -1 on timeout or error (see errno).
+ */
+int
+waitrfd(int fd, int *timeoutp) {
+        return waitfd(fd, timeoutp, POLLIN);
+}
+
+/*
  * Attempt a non-blocking connect(2) to the specified address, waiting up to
  * *timeoutp milliseconds for the connection to complete. If the timeout is
  * <=0, then wait indefinitely.
@@ -295,7 +305,7 @@ timeout_connect(int sockfd, const struct sockaddr *serv_addr,
         } else if (errno != EINPROGRESS)
                 return -1;
 
-        if (waitrfd(sockfd, timeoutp) == -1)
+        if (waitfd(sockfd, timeoutp, POLLIN | POLLOUT) == -1)
                 return -1;
 
         /* Completed or failed */