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[OSX] ip_mreqn struct is not supported for IPv4 Multicast #119354

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Merged
merged 6 commits into from
Sep 9, 2025
+24 −1
Merged

[OSX] ip_mreqn struct is not supported for IPv4 Multicast #119354

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5cc12a8
Fix IPv4 multicast on macOS by handling ip_mreqn struct compatibility
liveans Sep 5, 2025
a408dd6
Remove Active Issue for iOS
liveans Sep 5, 2025
46c56f1
Add support for IP_MULTICAST_IFINDEX
liveans Sep 8, 2025
3be47f1
Refactor IPv4 multicast option handling to directly use IP_MULTICAST_…
liveans Sep 8, 2025
9089eb0
Accept 0 interface as valid
liveans Sep 8, 2025
dc68628
Merge branch 'main' into ipv4_multicast_osx_fix
wfurt Sep 8, 2025
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1 change: 0 additions & 1 deletion src/libraries/System.Net.Sockets/tests/FunctionalTests/SocketOptionNameTest.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -70,7 +70,6 @@ public void MulticastOption_CreateSocketSetGetOption_GroupAndInterfaceIndex_SetS
}

[ConditionalFact(nameof(CanRunMulticastTests))]
[ActiveIssue("https://github.com/dotnet/runtime/issues/113827", typeof(PlatformDetection), nameof(PlatformDetection.IsAppleMobile))]
public async Task MulticastInterface_Set_AnyInterface_Succeeds()
{
// On all platforms, index 0 means "any interface"
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30 changes: 30 additions & 0 deletions src/native/libs/System.Native/pal_networking.c
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Expand Up @@ -1186,6 +1186,28 @@ int32_t SystemNative_GetIPv4MulticastOption(intptr_t socket, int32_t multicastOp
return Error_SUCCESS;
}

#ifdef __APPLE__
static int32_t Apple_SetIPv4MulticastInterface(int fd, IPv4MulticastOption* option)
{
if (option->InterfaceIndex != 0)
{
// On Apple platforms, IP_MULTICAST_IF with interface index uses the interface index directly
uint32_t ifindex = (uint32_t)option->InterfaceIndex;
int err = setsockopt(fd, IPPROTO_IP, IP_MULTICAST_IFINDEX, &ifindex, sizeof(ifindex));
return err == 0 ? Error_SUCCESS : SystemNative_ConvertErrorPlatformToPal(errno);
}
else
{
struct ip_mreq opt;
memset(&opt, 0, sizeof(struct ip_mreq));
opt.imr_multiaddr.s_addr = option->MulticastAddress;
opt.imr_interface.s_addr = option->LocalAddress;
int err = setsockopt(fd, IPPROTO_IP, IP_MULTICAST_IF, &opt, sizeof(opt));
return err == 0 ? Error_SUCCESS : SystemNative_ConvertErrorPlatformToPal(errno);
}
}
#endif

int32_t SystemNative_SetIPv4MulticastOption(intptr_t socket, int32_t multicastOption, IPv4MulticastOption* option)
{
if (option == NULL)
Expand All @@ -1201,6 +1223,14 @@ int32_t SystemNative_SetIPv4MulticastOption(intptr_t socket, int32_t multicastOp
return Error_EINVAL;
}

#ifdef __APPLE__
// Special handling for IP_MULTICAST_IF on Apple platforms
if (optionName == SocketOptionName_SO_IP_MULTICAST_IF)
{
return Apple_SetIPv4MulticastInterface(fd, option);
}
#endif

#if HAVE_IP_MREQN
struct ip_mreqn opt;
memset(&opt, 0, sizeof(struct ip_mreqn));
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