Re: [PATCH] generic/131: dynamically allocate tcp listen port to avoid port clashes

Tahsin Erdogan
2016-06-10T19:48:29Z

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On Wed, Jun 8, 2016 at 11:52 AM, Tahsin Erdogan <tahsin@google.com> wrote:
> Current port selection algorithm is bound to have port clashes. To
> eliminate clashes, let server pick an unused port and report it on
> stdout.
>
> Signed-off-by: Tahsin Erdogan <tahsin@google.com>
> ---
> src/locktest.c | 16 +++++++++++++++-
> tests/generic/131 | 17 +++++++----------
> 2 files changed, 22 insertions(+), 11 deletions(-)
>
> diff --git a/src/locktest.c b/src/locktest.c
> index adf8ce0..eab48e2 100644
> --- a/src/locktest.c
> +++ b/src/locktest.c
> @@ -95,7 +95,7 @@ static char *filename = 0;
> static int debug = 0;
> static int server = 1;
> static int maxio = 8192;
> -static int port = 7890;
> +static int port = 0;
> static int testnumber = -1;
> static int saved_errno = 0;
>
> @@ -899,6 +899,20 @@ main(int argc, char *argv[])
> /*NOTREACHED*/
> }
>
> + if (port == 0) {
> + socklen_t addr_len = sizeof(myAddr);
> +
> + if (getsockname(s_fd, &myAddr, &addr_len)) {
> + perror("getsockname");
> + exit(1);
> + }
> +
> + port = ntohs(myAddr.sin_port);
> + }
> +
> + printf("server port: %d\n", port);
> + fflush(stdout);
> +
> c_fd = accept(s_fd, NULL, NULL);
> if (c_fd == INVALID_SOCKET) {
> perror("accept");
> diff --git a/tests/generic/131 b/tests/generic/131
> index 3bcb0d1..d64ba55 100755
> --- a/tests/generic/131
> +++ b/tests/generic/131
> @@ -49,21 +49,18 @@ _require_test_fcntl_advisory_locks
>
> TESTFILE=$TEST_DIR/lock_file
>
> -# Grab a port which is hopefully unused
> -if [ $$ -gt 1024 -a $$ -lt 32000 ]; then
> - PORT=$$
> -elif [ $$ -lt 1024 ]; then
> - PORT=$(($$+1024))
> -elif [ $$ -gt 32000 ]; then
> - PORT=$(($$%30000+1024))
> -fi
> -
> # Start the server
> -src/locktest -p $PORT $TESTFILE 2>&1 > $TEST_DIR/server.out &
> +src/locktest $TESTFILE 2>&1 > $TEST_DIR/server.out &
> locktest_pid1=$!
>
> sleep 1
>
> +PORT=$(cat $TEST_DIR/server.out | grep "^server port: " | awk '{print $3}')
> +if [ -z $PORT ]; then
> + echo "Could not get server port"
> + exit 1
> +fi
> +
> # Start the client
> src/locktest -p $PORT -h localhost $TESTFILE 2>&1 > $TEST_DIR/client.out
> locktest_pid2=$!
> --
> 2.8.0.rc3.226.g39d4020
>