Adding upstream version 3.4.23.upstream/3.4.23upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 163 insertions, 0 deletions

diff --git a/src/util/vstream_tweak.c b/src/util/vstream_tweak.c
new file mode 100644
index 0000000..a2e220c
--- /dev/null
+++ b/src/util/vstream_tweak.c
@@ -0,0 +1,163 @@
+/*++
+/* NAME
+/*	vstream_tweak 3
+/* SUMMARY
+/*	performance tweaks
+/* SYNOPSIS
+/*	#include <vstream.h>
+/*
+/*	VSTREAM	*vstream_tweak_sock(stream)
+/*	VSTREAM	*stream;
+/*
+/*	VSTREAM	*vstream_tweak_tcp(stream)
+/*	VSTREAM	*stream;
+/* DESCRIPTION
+/*	vstream_tweak_sock() does a best effort to boost your
+/*	network performance on the specified generic stream.
+/*
+/*	vstream_tweak_tcp() does a best effort to boost your
+/*	Internet performance on the specified TCP stream.
+/*
+/*	Arguments:
+/* .IP stream
+/*	The stream being boosted.
+/* DIAGNOSTICS
+/*	Panics: interface violations.
+/* LICENSE
+/* .ad
+/* .fi
+/*	The Secure Mailer license must be distributed with this software.
+/* AUTHOR(S)
+/*	Wietse Venema
+/*	IBM T.J. Watson Research
+/*	P.O. Box 704
+/*	Yorktown Heights, NY 10598, USA
+/*--*/
+
+/* System library. */
+
+#include <sys_defs.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <netinet/tcp.h>
+#include <errno.h>
+
+/* Utility library. */
+
+#include <msg.h>
+#include <vstream.h>
+
+/* Application-specific. */
+
+#ifdef HAS_IPV6
+#define SOCKADDR_STORAGE struct sockaddr_storage
+#else
+#define SOCKADDR_STORAGE struct sockaddr
+#endif
+
+/* vstream_tweak_sock - boost your generic network performance */
+
+int     vstream_tweak_sock(VSTREAM *fp)
+{
+    SOCKADDR_STORAGE ss;
+    struct sockaddr *sa = (struct sockaddr *) &ss;
+    SOCKADDR_SIZE sa_length = sizeof(ss);
+    int     ret;
+
+    /*
+     * If the caller doesn't know if this socket is AF_LOCAL, AF_INET, etc.,
+     * figure it out for them.
+     */
+    if ((ret = getsockname(vstream_fileno(fp), sa, &sa_length)) >= 0) {
+	switch (sa->sa_family) {
+#ifdef AF_INET6
+	case AF_INET6:
+#endif
+	case AF_INET:
+	    ret = vstream_tweak_tcp(fp);
+	    break;
+	}
+    }
+    return (ret);
+}
+
+/* vstream_tweak_tcp - boost your TCP performance */
+
+int     vstream_tweak_tcp(VSTREAM *fp)
+{
+    const char *myname = "vstream_tweak_tcp";
+    int     mss = 0;
+    SOCKOPT_SIZE mss_len = sizeof(mss);
+    int     err;
+
+    /*
+     * Avoid Nagle delays when VSTREAM buffers are smaller than the MSS.
+     * 
+     * Forcing TCP_NODELAY to be "always on" would hurt performance in the
+     * common case where VSTREAM buffers are larger than the MSS.
+     * 
+     * Instead we ask the kernel what the current MSS is, and take appropriate
+     * action. Linux <= 2.2 getsockopt(TCP_MAXSEG) always returns zero (or
+     * whatever value was stored last with setsockopt()).
+     * 
+     * Some ancient FreeBSD kernels don't report 'host unreachable' errors with
+     * getsockopt(SO_ERROR), and then treat getsockopt(TCP_MAXSEG) as a NOOP,
+     * leaving the mss parameter value unchanged. To work around these two
+     * getsockopt() bugs we set mss = 0, which is a harmless value.
+     */
+    if ((err = getsockopt(vstream_fileno(fp), IPPROTO_TCP, TCP_MAXSEG,
+			  (void *) &mss, &mss_len)) < 0
+	&& errno != ECONNRESET) {
+	msg_warn("%s: getsockopt TCP_MAXSEG: %m", myname);
+	return (err);
+    }
+    if (msg_verbose)
+	msg_info("%s: TCP_MAXSEG %d", myname, mss);
+
+    /*
+     * Fix for recent Postfix versions: increase the VSTREAM buffer size if
+     * it is smaller than the MSS. Note: the MSS may change when the route
+     * changes and IP path MTU discovery is turned on, so we choose a
+     * somewhat larger buffer.
+     * 
+     * Note: as of 20120527, the CA_VSTREAM_CTL_BUFSIZE request can reduce the
+     * stream buffer size to less than VSTREAM_BUFSIZE, when the request is
+     * made before the first stream read or write operation. We don't want to
+     * reduce the buffer size.
+     * 
+     * As of 20190820 we increase the mss size multipler from 2x to 4x, because
+     * some LINUX loopback TCP stacks report an MSS of 21845 which is 3x
+     * smaller than the MTU of 65536. Even with a VSTREAM buffer 2x the
+     * reported MSS size, performance would suck due to Nagle or delayed ACK
+     * delays.
+     */
+#define EFF_BUFFER_SIZE(fp) (vstream_req_bufsize(fp) ? \
+		vstream_req_bufsize(fp) : VSTREAM_BUFSIZE)
+
+#ifdef CA_VSTREAM_CTL_BUFSIZE
+    if (mss > EFF_BUFFER_SIZE(fp) / 4) {
+	if (mss < INT_MAX / 2)
+	    mss *= 2;
+	if (mss < INT_MAX / 2)
+	    mss *= 2;
+	vstream_control(fp,
+			CA_VSTREAM_CTL_BUFSIZE(mss),
+			CA_VSTREAM_CTL_END);
+    }
+
+    /*
+     * Workaround for older Postfix versions: turn on TCP_NODELAY if the
+     * VSTREAM buffer size is smaller than the MSS.
+     */
+#else
+    if (mss > VSTREAM_BUFSIZE) {
+	int     nodelay = 1;
+
+	if ((err = setsockopt(vstream_fileno(fp), IPPROTO_TCP, TCP_NODELAY,
+			      (void *) &nodelay, sizeof(nodelay))) < 0
+	    && errno != ECONNRESET)
+	    msg_warn("%s: setsockopt TCP_NODELAY: %m", myname);
+    }
+#endif
+    return (err);
+}