btashton commented on a change in pull request #2415:
URL: https://github.com/apache/incubator-nuttx/pull/2415#discussion_r536575892
##########
File path: net/inet/ipv4_setsockopt.c
##########
@@ -184,16 +189,41 @@ int ipv4_setsockopt(FAR struct socket *psock, int option,
}
break;
- /* The following IPv4 socket options are defined, but not implemented */
-
- case IP_MULTICAST_IF: /* Set local device for a multicast
- * socket */
case IP_MULTICAST_TTL: /* Set/read the time-to-live value of
* outgoing multicast packets */
+ {
+ if (psock->s_type != SOCK_DGRAM ||
+ value_len != sizeof(int))
Review comment:
bsd and as well as tldp and ltp all use uchar
```
The IP_MULTICAST_TTL option changes the time-to-live (TTL) for
outgoing
multicast datagrams in order to control the scope of the multicasts:
u_char ttl; /* range: 0 to 255, default = 1 */
setsockopt(s, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl));
```
The linux man 7 ip page is unfortunate because it seems to be playing loose
with the word `integer`
```
IP_MULTICAST_TTL (since Linux 1.2)
Set or read the time-to-live value of outgoing multicast pack‐
ets for this socket. It is very important for multicast pack‐
ets to set the smallest TTL possible. The default is 1 which
means that multicast packets don't leave the local network un‐
less the user program explicitly requests it. Argument is an
integer.
```
However since there own test suite uses `uchar` and every usage of it I have
seen does as well I think it is clear.
https://github.com/linux-test-project/ltp/blob/master/testcases/network/multicast/mc_opts/mc_verify_opts.c
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