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 c9ba59078129523a2be9d9884b9b9f1c940d95b5..005583cf52bf425f67727df68600c1094a3c0ad8 100644 (file)
--- 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 880c83cf1078a5553880897466ec43bccb09bedf..adf233979c31e2aff79ecdf94b5b16fd6f8765da 100644 (file)
--- 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"