bpf: add sendmsg option for testing BPF programs

When testing BPF programs using sockmap I often want to have more
control over how sendmsg is exercised. This becomes even more useful
as new sockmap program types are added.

This adds a test type option to select type of test to run. Currently,
only "ping" and "sendmsg" are supported, but more can be added as
needed.

The new help argument gives the following,

 Usage: ./sockmap --cgroup <cgroup_path>
 options:
 --help         -h
 --cgroup       -c
 --rate         -r
 --verbose      -v
 --iov_count    -i
 --length       -l
 --test         -t
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

samples/sockmap/sockmap_user.c

@@ -56,6 +56,9 @@ static const struct option long_options[] = {
 	{"cgroup",	required_argument,	NULL, 'c' },
 	{"rate",	required_argument,	NULL, 'r' },
 	{"verbose",	no_argument,		NULL, 'v' },
+	{"iov_count",	required_argument,	NULL, 'i' },
+	{"length",	required_argument,	NULL, 'l' },
+	{"test",	required_argument,	NULL, 't' },
 	{0, 0, NULL, 0 }
 };
 
@@ -182,6 +185,118 @@ static int sockmap_init_sockets(void)
 	return 0;
 }
 
+struct msg_stats {
+	size_t bytes_sent;
+	size_t bytes_recvd;
+};
+
+static int msg_loop(int fd, int iov_count, int iov_length, int cnt,
+		    struct msg_stats *s, bool tx)
+{
+	struct msghdr msg = {0};
+	struct iovec *iov;
+	int i, flags = 0;
+
+	iov = calloc(iov_count, sizeof(struct iovec));
+	if (!iov)
+		return errno;
+
+	for (i = 0; i < iov_count; i++) {
+		char *d = calloc(iov_length, sizeof(char));
+
+		if (!d) {
+			fprintf(stderr, "iov_count %i/%i OOM\n", i, iov_count);
+			goto out_errno;
+		}
+		iov[i].iov_base = d;
+		iov[i].iov_len = iov_length;
+	}
+
+	msg.msg_iov = iov;
+	msg.msg_iovlen = iov_count;
+
+	if (tx) {
+		for (i = 0; i < cnt; i++) {
+			int sent = sendmsg(fd, &msg, flags);
+
+			if (sent < 0) {
+				perror("send loop error:");
+				goto out_errno;
+			}
+			s->bytes_sent += sent;
+		}
+	} else {
+		int slct, recv, max_fd = fd;
+		struct timeval timeout;
+		float total_bytes;
+		fd_set w;
+
+		total_bytes = (float)iov_count * (float)iov_length * (float)cnt;
+		while (s->bytes_recvd < total_bytes) {
+			timeout.tv_sec = 1;
+			timeout.tv_usec = 0;
+
+			/* FD sets */
+			FD_ZERO(&w);
+			FD_SET(fd, &w);
+
+			slct = select(max_fd + 1, &w, NULL, NULL, &timeout);
+			if (slct == -1) {
+				perror("select()");
+				goto out_errno;
+			} else if (!slct) {
+				fprintf(stderr, "unexpected timeout\n");
+				errno = -EIO;
+				goto out_errno;
+			}
+
+			recv = recvmsg(fd, &msg, flags);
+			if (recv < 0) {
+				if (errno != EWOULDBLOCK) {
+					perror("recv failed()\n");
+					goto out_errno;
+				}
+			}
+
+			s->bytes_recvd += recv;
+		}
+	}
+
+	for (i = 0; i < iov_count; i++)
+		free(iov[i].iov_base);
+	free(iov);
+	return 0;
+out_errno:
+	for (i = 0; i < iov_count; i++)
+		free(iov[i].iov_base);
+	free(iov);
+	return errno;
+}
+
+static int sendmsg_test(int iov_count, int iov_buf, int cnt, int verbose)
+{
+	struct msg_stats s = {0};
+	int err;
+
+	err = msg_loop(c1, iov_count, iov_buf, cnt, &s, true);
+	if (err) {
+		fprintf(stderr,
+			"msg_loop_tx: iov_count %i iov_buf %i cnt %i err %i\n",
+			iov_count, iov_buf, cnt, err);
+		return err;
+	}
+
+	err = msg_loop(p2, iov_count, iov_buf, cnt, &s, false);
+	if (err)
+		fprintf(stderr,
+			"msg_loop_rx: iov_count %i iov_buf %i cnt %i err %i\n",
+			iov_count, iov_buf, cnt, err);
+
+	fprintf(stdout, "sendmsg: TX_bytes %zu RX_bytes %zu\n",
+		s.bytes_sent, s.bytes_recvd);
+	return err;
+}
+
 static int forever_ping_pong(int rate, int verbose)
 {
 	struct timeval timeout;
@@ -257,13 +372,19 @@ static int forever_ping_pong(int rate, int verbose)
 	return 0;
 }
 
+enum {
+	PING_PONG,
+	SENDMSG,
+};
+
 int main(int argc, char **argv)
 {
-	int rate = 1, verbose = 0;
+	int iov_count = 1, length = 1024, rate = 1, verbose = 0;
 	int opt, longindex, err, cg_fd = 0;
+	int test = PING_PONG;
 	char filename[256];
 
-	while ((opt = getopt_long(argc, argv, "hvc:r:",
+	while ((opt = getopt_long(argc, argv, "hvc:r:i:l:t:",
 				  long_options, &longindex)) != -1) {
 		switch (opt) {
 		/* Cgroup configuration */
@@ -282,6 +403,22 @@ int main(int argc, char **argv)
 		case 'v':
 			verbose = 1;
 			break;
+		case 'i':
+			iov_count = atoi(optarg);
+			break;
+		case 'l':
+			length = atoi(optarg);
+			break;
+		case 't':
+			if (strcmp(optarg, "ping") == 0) {
+				test = PING_PONG;
+			} else if (strcmp(optarg, "sendmsg") == 0) {
+				test = SENDMSG;
+			} else {
+				usage(argv);
+				return -1;
+			}
+			break;
 		case 'h':
 		default:
 			usage(argv);
@@ -339,7 +476,12 @@ int main(int argc, char **argv)
 		goto out;
 	}
 
-	err = forever_ping_pong(rate, verbose);
+	if (test == PING_PONG)
+		err = forever_ping_pong(rate, verbose);
+	else if (test == SENDMSG)
+		err = sendmsg_test(iov_count, length, rate, verbose);
+	else
+		fprintf(stderr, "unknown test\n");
 out:
 	close(s1);
 	close(s2);