IP Don't fragment bit on Mac OS

Question

I am writing a file transferring program over TCP.

I want to set the don\'t fragment flag on IP

On a socket this is what I want to do:

int va         


        

Answer 1

Looking at /Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/System/Library/Frameworks/Kernel.framework/Versions/A/Headers it seems to be called IP_DF here:

netinet/ip.h
99:#define IP_DF 0x4000                    /* dont fragment flag */
netinet6/in6.h
547:#define IPV6_DONTFRAG           62 /* bool; disable IPv6 fragmentation */