Compilation errors occur on Windows if UA_IPV6 is not defined

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Background Information / Reproduction Steps

Change ua_architecture.h to remove the definition of UA_IPV6. The eventloop_posix_udp.c file will then fail to compile due to the Win32 setMulticastInterface method assuming that IPV6 is always enabled. The non-Windows method is OK.

Solution

Change the done statement in the setMulticastInterface method from this:

 done:
    /* Write the interface index */
    if(info->ai_family == AF_INET)
        /* MSVC documentation of struct ip_mreq: To use an interface index of 1
         * would be the same as an IP address of 0.0.0.1. */
        req->ipv4.imr_interface.s_addr = htonl(idx);
    else /* if(info->ai_family == AF_INET6) */
        req->ipv6.ipv6mr_interface = idx;
    return UA_STATUSCODE_GOOD;

To this:

 done:
    /* Write the interface index */
    if(info->ai_family == AF_INET)
        /* MSVC documentation of struct ip_mreq: To use an interface index of 1
         * would be the same as an IP address of 0.0.0.1. */
        req->ipv4.imr_interface.s_addr = htonl(idx);
#if UA_IPV6
    else /* if(info->ai_family == AF_INET6) */
        req->ipv6.ipv6mr_interface = idx;
#endif
    return UA_STATUSCODE_GOOD;

Checklist

Please provide the following information:

• open62541 Version (release number or git tag): 1.4.1
• Other OPC UA SDKs used (client or server):
• Operating system: Windows 11
• Logs (with UA_LOGLEVEL set as low as necessary) attached
• Wireshark network dump attached
• Self-contained code example attached
• Critical issue