From: Gerrit Renker <grenker@cscs.ch>
Date: Sun, 13 Jun 2010 09:30:47 +0000 (+0200)
Subject: fec: make max_slice_size optional
X-Git-Tag: v0.4.3~8^2
X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=commitdiff_plain;h=ace5a88d69e5d41ce4959b43d278cc1c8db93706

fec: make max_slice_size optional

The default max_slice_size for FEC is the MTU. This patch changes the parser
to make the specification of the max_slice_size optional (for cases using a
slice size less than the MTU).

Other changes:
 * added udp sender help documentation;
 * simplified parse_fec_url() (no additional strlen() needed).
---

diff --git a/send_common.c b/send_common.c
index c9ba5907..005583cf 100644
--- a/send_common.c
+++ b/send_common.c
@@ -341,47 +341,51 @@ char *generic_sender_help(void)
 static int parse_fec_parms(const char *arg, struct sender_command_data *scd)
 {
 	int32_t val;
-	char *a = para_strdup(arg), *b = a, *e = strchr(b, ':');
+	char *a = para_strdup(arg),
+	     *b = strchr(a, ':'),
+	     *c = strrchr(a, ':');
 	int ret = -E_COMMAND_SYNTAX;
 
-	/* parse max slice bytes */
-	if (!e)
+	if (!b || !c)
 		goto out;
-	*e = '\0';
-	ret = para_atoi32(b, &val);
-	if (ret < 0)
-		goto out;
-	ret = -ERRNO_TO_PARA_ERROR(EINVAL);
-	if (val < 0 || val > 65535)
-		goto out;
-	scd->max_slice_bytes = val;
-	/* parse data_slices_per_group */
-	b = e + 1;
-	e = strchr(b, ':');
-	ret = -E_COMMAND_SYNTAX;
-	if (!e)
-		goto out;
-	*e = '\0';
-	ret = para_atoi32(b, &val);
+	*b = *c = '\0';
+
+	ret = para_atoi32(a, &val);
 	if (ret < 0)
 		goto out;
-	ret = -ERRNO_TO_PARA_ERROR(EINVAL);
+
+	/* optional max_slice_bytes (0 means "use MTU") */
+	if (b == c) {
+		scd->max_slice_bytes = 0;
+	} else {
+		if (val < 0 || val > 65535)
+			goto fec_einval;
+		scd->max_slice_bytes = val;
+
+		ret = para_atoi32(b + 1, &val);
+		if (ret < 0)
+			goto out;
+	}
+
+	/* k = data_slices_per_group */
 	if (val < 0 || val > 255)
-		goto out;
+		goto fec_einval;
 	scd->data_slices_per_group = val;
-	/* parse slices_per_group */
-	b = e + 1;
-	ret = para_atoi32(b, &val);
+
+	/* n = slices_per_group */
+	ret = para_atoi32(c + 1, &val);
 	if (ret < 0)
 		goto out;
-	ret = -ERRNO_TO_PARA_ERROR(EINVAL);
 	if (val < 0 || val < scd->data_slices_per_group)
-		goto out;
+		goto fec_einval;
 	scd->slices_per_group = val;
 	ret = 0;
 out:
 	free(a);
 	return ret;
+fec_einval:
+	ret = -ERRNO_TO_PARA_ERROR(EINVAL);
+	goto out;
 }
 
 /**
@@ -401,26 +405,22 @@ out:
  */
 int parse_fec_url(const char *arg, struct sender_command_data *scd)
 {
-	int ret;
-	ssize_t len = sizeof(scd->host);
 	char *a = para_strdup(arg), *p = strchr(a, '/');
+	int ret = 0;
+
+	/* default fec parameters */
+	scd->max_slice_bytes	   = 0;
+	scd->data_slices_per_group = 14;
+	scd->slices_per_group	   = 16;
 
 	if (p) {
 		*p = '\0';
-		len = strlen(a);
-	}
-	ret = -ERRNO_TO_PARA_ERROR(EINVAL);
-	if (!parse_url(a, scd->host, len, &scd->port))
-		goto out;
-	if (p) {
 		ret = parse_fec_parms(p + 1, scd);
-		goto out;
+		if (ret < 0)
+			goto out;
 	}
-	/* use default fec parameters. */
-	scd->max_slice_bytes = 0;
-	scd->slices_per_group = 16;
-	scd->data_slices_per_group = 14;
-	ret = 0;
+	if (!parse_url(a, scd->host, sizeof(scd->host), &scd->port))
+		ret = -ERRNO_TO_PARA_ERROR(EINVAL);
 out:
 	free(a);
 	return ret;
diff --git a/udp_send.c b/udp_send.c
index 880c83cf..adf23397 100644
--- a/udp_send.c
+++ b/udp_send.c
@@ -422,11 +422,12 @@ static char *udp_help(void)
 {
 	return make_message(
 		"usage: {on|off}\n"
-		"usage: {add|delete} host[:port][/packet_size:k:n]\n"
+		"usage: {add|delete} ip_address[:port][/[packet_size:]k:n]\n"
+		"       - k is the number of data slices per FEC group\n"
+		"       - n is the total number of slices in a FEC group\n"
+		"       - packet_size reduces the slice size below path MTU\n\n"
 		"examples: add 224.0.1.38:1500  (IPv4 multicast)\n"
-		"          add 224.0.1.38:1500/1400:14:16\n"
-		"              (likewise, using 1400 byte packets, with 14\n"
-		"               data slices per 16 slice FEC group)\n"
+		"          add 224.0.1.38:8080/14:16 (explicit FEC)\n"
 		"          add 10.10.1.42       (using default port)\n"
 		"          add [FF05::42]:1500  (IPv6 multicast)\n"
 		"          add [::1]            (IPv6 localhost/default port)\n"