libvchan: interdomain communications library

This library implements a bidirectional communication interface between
applications in different domains, similar to unix sockets. Data can be
sent using the byte-oriented libvchan_read/libvchan_write or the
packet-oriented libvchan_recv/libvchan_send.

Channel setup is done using a client-server model; domain IDs and a port
number must be negotiated prior to initialization. The server allocates
memory for the shared pages and determines the sizes of the
communication rings (which may span multiple pages, although the default
places rings and control within a single page).

With properly sized rings, testing has shown that this interface
provides speed comparable to pipes within a single Linux domain; it is
significantly faster than network-based communication.

Signed-off-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>

1 files changed, 162 insertions, 0 deletions

diff --git a/tools/libvchan/node-select.c b/tools/libvchan/node-select.c
new file mode 100644
index 0000000000..6c6c19eec6
--- /dev/null
+++ b/tools/libvchan/node-select.c
@@ -0,0 +1,162 @@
+/**
+ * @file
+ * @section AUTHORS
+ *
+ * Copyright (C) 2010  Rafal Wojtczuk  <rafal@invisiblethingslab.com>
+ *
+ *  Authors:
+ *       Rafal Wojtczuk  <rafal@invisiblethingslab.com>
+ *       Daniel De Graaf <dgdegra@tycho.nsa.gov>
+ *
+ * @section LICENSE
+ *
+ *  This program is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU Lesser General Public
+ *  License as published by the Free Software Foundation; either
+ *  version 2.1 of the License, or (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *  Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public
+ *  License along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA
+ *
+ * @section DESCRIPTION
+ *
+ * This is a test program for libxenvchan.  Communications are bidirectional,
+ * with either server (grant offeror) or client able to read and write.
+ */
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>
+
+#include <libxenvchan.h>
+
+void usage(char** argv)
+{
+	fprintf(stderr, "usage:\n"
+		"\t%s [client|server] domainid nodepath [rbufsiz wbufsiz]\n",
+		argv[0]);
+	exit(1);
+}
+
+#define BUFSIZE 5000
+char inbuf[BUFSIZE];
+char outbuf[BUFSIZE];
+int insiz = 0;
+int outsiz = 0;
+struct libxenvchan *ctrl = 0;
+
+void vchan_wr() {
+	if (!insiz)
+		return;
+	int ret = libxenvchan_write(ctrl, inbuf, insiz);
+	if (ret < 0) {
+		fprintf(stderr, "vchan write failed\n");
+		exit(1);
+	}
+	if (ret > 0) {
+		insiz -= ret;
+		memmove(inbuf, inbuf + ret, insiz);
+	}
+}
+
+void stdout_wr() {
+	if (!outsiz)
+		return;
+	int ret = write(1, outbuf, outsiz);
+	if (ret < 0 && errno != EAGAIN)
+		exit(1);
+	if (ret > 0) {
+		outsiz -= ret;
+		memmove(outbuf, outbuf + ret, outsiz);
+	}
+}
+
+/**
+    Simple libxenvchan application, both client and server.
+	Both sides may write and read, both from the libxenvchan and from 
+	stdin/stdout (just like netcat).
+*/
+
+int main(int argc, char **argv)
+{
+	int ret;
+	int libxenvchan_fd;
+	if (argc < 4 || argv[3][0] != '/')
+		usage(argv);
+	if (!strcmp(argv[1], "server")) {
+		int rsiz = argc > 4 ? atoi(argv[4]) : 0;
+		int wsiz = argc > 5 ? atoi(argv[5]) : 0;
+		ctrl = libxenvchan_server_init(NULL, atoi(argv[2]), argv[3], rsiz, wsiz);
+	} else if (!strcmp(argv[1], "client"))
+		ctrl = libxenvchan_client_init(NULL, atoi(argv[2]), argv[3]);
+	else
+		usage(argv);
+	if (!ctrl) {
+		perror("libxenvchan_*_init");
+		exit(1);
+	}
+
+	fcntl(0, F_SETFL, O_NONBLOCK);
+	fcntl(1, F_SETFL, O_NONBLOCK);
+
+	libxenvchan_fd = libxenvchan_fd_for_select(ctrl);
+	for (;;) {
+		fd_set rfds;
+		fd_set wfds;
+		FD_ZERO(&rfds);
+		FD_ZERO(&wfds);
+		if (insiz != BUFSIZE)
+			FD_SET(0, &rfds);
+		if (outsiz)
+			FD_SET(1, &wfds);
+		FD_SET(libxenvchan_fd, &rfds);
+		ret = select(libxenvchan_fd + 1, &rfds, &wfds, NULL, NULL);
+		if (ret < 0) {
+			perror("select");
+			exit(1);
+		}
+		if (FD_ISSET(0, &rfds)) {
+			ret = read(0, inbuf + insiz, BUFSIZE - insiz);
+			if (ret < 0 && errno != EAGAIN)
+				exit(1);
+			if (ret == 0) {
+				while (insiz) {
+					vchan_wr();
+					libxenvchan_wait(ctrl);
+				}
+				return 0;
+			}
+			if (ret)
+				insiz += ret;
+			vchan_wr();
+		}
+		if (FD_ISSET(libxenvchan_fd, &rfds)) {
+			libxenvchan_wait(ctrl);
+			vchan_wr();
+		}
+		if (FD_ISSET(1, &wfds))
+			stdout_wr();
+		while (libxenvchan_data_ready(ctrl) && outsiz < BUFSIZE) {
+			ret = libxenvchan_read(ctrl, outbuf + outsiz, BUFSIZE - outsiz);
+			if (ret < 0)
+				exit(1);
+			outsiz += ret;
+			stdout_wr();
+		}
+		if (!libxenvchan_is_open(ctrl)) {
+			fcntl(1, F_SETFL, 0);
+			while (outsiz)
+				stdout_wr();
+			return 0;
+		}
+	}
+}