1 files changed, 145 insertions, 0 deletions
diff --git a/test/core/util/port.c b/test/core/util/port.c
new file mode 100644
index 0000000000..133b53fd2b
--- /dev/null
+++ b/test/core/util/port.c
@@ -0,0 +1,145 @@
+/*
+ *
+ * Copyright 2014, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include "test/core/util/port.h"
+
+#include <netinet/in.h>
+#include <sys/socket.h>
+#include <stdio.h>
+#include <errno.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <grpc/support/log.h>
+
+#define NUM_RANDOM_PORTS_TO_PICK 100
+
+static int is_port_available(int *port, int is_tcp) {
+  const int proto = is_tcp ? IPPROTO_TCP : 0;
+  const int fd = socket(AF_INET, is_tcp ? SOCK_STREAM : SOCK_DGRAM, proto);
+  int one = 1;
+  struct sockaddr_in addr;
+  socklen_t alen = sizeof(addr);
+  int actual_port;
+
+  GPR_ASSERT(*port >= 0);
+  GPR_ASSERT(*port <= 65535);
+  if (fd < 0) {
+    gpr_log(GPR_ERROR, "socket() failed: %s", strerror(errno));
+    return 0;
+  }
+
+  /* Reuseaddr lets us start up a server immediately after it exits */
+  if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one)) < 0) {
+    gpr_log(GPR_ERROR, "setsockopt() failed: %s", strerror(errno));
+    close(fd);
+    return 0;
+  }
+
+  /* Try binding to port */
+  addr.sin_family = AF_INET;
+  addr.sin_addr.s_addr = INADDR_ANY;
+  addr.sin_port = htons(*port);
+  if (bind(fd, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
+    gpr_log(GPR_DEBUG, "bind(port=%d) failed: %s", *port, strerror(errno));
+    close(fd);
+    return 0;
+  }
+
+  /* Get the bound port number */
+  if (getsockname(fd, (struct sockaddr *)&addr, &alen) < 0) {
+    gpr_log(GPR_ERROR, "getsockname() failed: %s", strerror(errno));
+    close(fd);
+    return 0;
+  }
+  GPR_ASSERT(alen <= sizeof(addr));
+  actual_port = ntohs(addr.sin_port);
+  GPR_ASSERT(actual_port > 0);
+  if (*port == 0) {
+    *port = actual_port;
+  } else {
+    GPR_ASSERT(*port == actual_port);
+  }
+
+  close(fd);
+  return 1;
+}
+
+int grpc_pick_unused_port() {
+  /* We repeatedly pick a port and then see whether or not it is
+     available for use both as a TCP socket and a UDP socket.  First, we
+     pick a random large port number.  For subsequent
+     iterations, we bind to an anonymous port and let the OS pick the
+     port number.  The random port picking reduces the probability of
+     races with other processes on kernels that want to reuse the same
+     port numbers over and over. */
+
+  /* In alternating iterations we try UDP ports before TCP ports UDP
+     ports -- it could be the case that this machine has been using up
+     UDP ports and they are scarcer. */
+
+  /* Type of port to first pick in next iteration */
+  int is_tcp = 1;
+  int try
+    = 0;
+
+  for (;;) {
+    int port = try
+      < NUM_RANDOM_PORTS_TO_PICK ? rand() % (65536 - 30000) + 30000 : 0;
+    if (!is_port_available(&port, is_tcp)) {
+      continue;
+    }
+    GPR_ASSERT(port > 0);
+    /* Check that the port # is free for the other type of socket also */
+    if (!is_port_available(&port, !is_tcp)) {
+      /* In the next iteration try to bind to the other type first
+         because perhaps it is more rare. */
+      is_tcp = !is_tcp;
+      continue;
+    }
+
+    /* TODO(ctiller): consider caching this port in some structure, to avoid
+                      handing it out again */
+
+    return port;
+  }
+
+  /* The port iterator reached the end without finding a suitable port. */
+  return 0;
+}
+
+int grpc_pick_unused_port_or_die() {
+  int port = grpc_pick_unused_port();
+  GPR_ASSERT(port > 0);
+  return port;
+}