This test program verifies that we can receive and discard datagrams by
using recv() with a NULL buffer and zero-length. Extend it to verify it
also works using recvmsg() and either an iov with a zero-length NULL
buffer or an iov that itself is NULL and zero-length.
Signed-off-by: David Gibson <david(a)gibson.dropbear.id.au>
---
doc/platform-requirements/recv-zero.c | 60 +++++++++++++++++++++++----
1 file changed, 52 insertions(+), 8 deletions(-)
diff --git a/doc/platform-requirements/recv-zero.c
b/doc/platform-requirements/recv-zero.c
index f161e5c2..ab27704d 100644
--- a/doc/platform-requirements/recv-zero.c
+++ b/doc/platform-requirements/recv-zero.c
@@ -23,11 +23,27 @@
#define DSTPORT 13257U
+enum discard_method {
+ DISCARD_NULL_BUF,
+ DISCARD_ZERO_IOV,
+ DISCARD_NULL_IOV,
+ NUM_METHODS,
+};
+
/* 127.0.0.1:DSTPORT */
static const struct sockaddr_in lo_dst = SOCKADDR_INIT(INADDR_LOOPBACK, DSTPORT);
-static void test_discard(void)
+static void test_discard(enum discard_method method)
{
+ struct iovec zero_iov = { .iov_base = NULL, .iov_len = 0, };
+ struct msghdr mh_zero = {
+ .msg_iov = &zero_iov,
+ .msg_iovlen = 1,
+ };
+ struct msghdr mh_null = {
+ .msg_iov = NULL,
+ .msg_iovlen = 0,
+ };
long token1, token2;
int recv_s, send_s;
ssize_t rc;
@@ -46,11 +62,36 @@ static void test_discard(void)
send_token(send_s, token1);
send_token(send_s, token2);
- /* cppcheck-suppress nullPointer */
- rc = recv(recv_s, NULL, 0, MSG_DONTWAIT);
- if (rc < 0)
- die("discarding recv(): %s\n", strerror(errno));
-
+ switch (method) {
+ case DISCARD_NULL_BUF:
+ /* cppcheck-suppress nullPointer */
+ rc = recv(recv_s, NULL, 0, MSG_DONTWAIT);
+ if (rc < 0)
+ die("discarding recv(): %s\n", strerror(errno));
+ break;
+
+ case DISCARD_ZERO_IOV:
+ rc = recvmsg(recv_s, &mh_zero, MSG_DONTWAIT);
+ if (rc < 0)
+ die("recvmsg() with zero-length buffer: %s\n",
+ strerror(errno));
+ if (!((unsigned)mh_zero.msg_flags & MSG_TRUNC))
+ die("Missing MSG_TRUNC flag\n");
+ break;
+
+ case DISCARD_NULL_IOV:
+ rc = recvmsg(recv_s, &mh_null, MSG_DONTWAIT);
+ if (rc < 0)
+ die("recvmsg() with zero-length iov: %s\n",
+ strerror(errno));
+ if (!((unsigned)mh_null.msg_flags & MSG_TRUNC))
+ die("Missing MSG_TRUNC flag\n");
+ break;
+
+ default:
+ die("Bad method\n");
+ }
+
recv_token(recv_s, token2);
/* cppcheck-suppress nullPointer */
@@ -63,12 +104,15 @@ static void test_discard(void)
int main(int argc, char *argv[])
{
+ enum discard_method method;
+
(void)argc;
(void)argv;
- test_discard();
+ for (method = 0; method < NUM_METHODS; method++)
+ test_discard(method);
- printf("Discarding datagrams with a 0-length recv() seems to work\n");
+ printf("Discarding datagrams with a 0-length receives seems to work\n");
exit(0);
}
--
2.45.2