[FFmpeg-devel] [PATCH] Fix setsockopt IP_MULTICAST_TTL on OpenBSD

["zhilizhao(赵志立)"]

> On Jan 27, 2022, at 9:59 AM, lance.lmwang at gmail.com wrote:
> 
> On Wed, Jan 26, 2022 at 09:50:47PM +0100, Marton Balint wrote:
>> 
>> 
>> On Wed, 26 Jan 2022, Brad Smith wrote:
>> 
>>> On Wed, Jan 12, 2022 at 12:13:14AM -0500, Brad Smith wrote:
>>>> Fix setsockopt() usage on OpenBSD with IP_MULTICAST_TTL. The field
>>>> type should be an unsigned char on anything but Linux.
>>> 
>>> Based on feedback so far. Here is a much simpler approach to this issue..
>> 
>> Win32 needs DWORD unfortunately. I missed it earlier, sorry.
>> 
>> https://docs.microsoft.com/en-us/windows/win32/winsock/ipproto-ip-socket-options
> 
> From my testing on Mac system, it support one byte only, but at least, it'll
> report "Invalid argument" only if the ttl > 255. Maybe we can try with one byte
> again if the errno is invalid like below. I tested it with ttl > 255 on Mac system
> and without "Invalid argument" anymore.


MacOS support int and unsigned char from my test. The upper bound of TTL is limited
to 255 (limited by protocol design), I guess it’s unrelated to int or unsigned char.


> 
> #ifdef IP_MULTICAST_TTL
> +    int ret = 0;
>     if (addr->sa_family == AF_INET) {
> -        if (setsockopt(sockfd, IPPROTO_IP, IP_MULTICAST_TTL, &mcastTTL, sizeof(mcastTTL)) < 0) {
> +        ret = setsockopt(sockfd, IPPROTO_IP, IP_MULTICAST_TTL, &mcastTTL, sizeof(mcastTTL));
> +        /* try with byte also for IP_MULTICAST_TTL for some system like OpenBSD */
> +        if (ret < 0 && errno == EINVAL) {
> +            unsigned char ttl = mcastTTL;
> +            ff_log_net_error(logctx, AV_LOG_ERROR, "setsockopt(IP_MULTICAST_TTL): ");
> +            ret = setsockopt(sockfd, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl));
> +        }
> +        if (ret < 0) {
>             ff_log_net_error(logctx, AV_LOG_ERROR, "setsockopt(IP_MULTICAST_TTL)");
>             return ff_neterrno();
> 
> 
>> 
>> Regards,
>> Marton
>> 
>>> 
>>> 
>>> diff --git a/libavformat/udp.c b/libavformat/udp.c
>>> index 83c042d079..da1b98890b 100644
>>> --- a/libavformat/udp.c
>>> +++ b/libavformat/udp.c
>>> @@ -164,7 +164,9 @@ static int udp_set_multicast_ttl(int sockfd, int mcastTTL,
>>> {
>>> #ifdef IP_MULTICAST_TTL
>>>    if (addr->sa_family == AF_INET) {
>>> -        if (setsockopt(sockfd, IPPROTO_IP, IP_MULTICAST_TTL, &mcastTTL, sizeof(mcastTTL)) < 0) {
>>> +        unsigned char ttl = mcastTTL;  /* ignore the outdated Linux documentation */
>>> +
>>> +        if (setsockopt(sockfd, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl)) < 0) {
>>>            ff_log_net_error(logctx, AV_LOG_ERROR, "setsockopt(IP_MULTICAST_TTL)");
>>>            return ff_neterrno();
>>>        }
>>> _______________________________________________
>>> ffmpeg-devel mailing list
>>> ffmpeg-devel at ffmpeg.org
>>> https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>>> 
>>> To unsubscribe, visit link above, or email
>>> ffmpeg-devel-request at ffmpeg.org with subject "unsubscribe".
>>> 
>> _______________________________________________
>> ffmpeg-devel mailing list
>> ffmpeg-devel at ffmpeg.org
>> https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>> 
>> To unsubscribe, visit link above, or email
>> ffmpeg-devel-request at ffmpeg.org with subject "unsubscribe".
> 
> -- 
> Thanks,
> Limin Wang
> _______________________________________________
> ffmpeg-devel mailing list
> ffmpeg-devel at ffmpeg.org
> https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
> 
> To unsubscribe, visit link above, or email
> ffmpeg-devel-request at ffmpeg.org with subject "unsubscribe".