x/net/ipv4: No easy way to set header flags

[gopherbot]

by Marko.Silokunnas:

Current implementation of ipv4.Header doesn't have an easy way to set flags
of the header. RFC791 defines that the flags field of the header is 3 bits 
wide and the fragment offset field is 13 bits wide. In the current implementation
of ipv4.Header fragment offset is defined as an int and marshaled into a 16 bit 
wide field in Marshal(). This allows the flags to be set by manually using bitwise 
operations, but it is rather ugly. 

I propose that a Flags field should be added to ipv4.Header and the marshalling
and unmarshalling functions should take care of the rest.

[gopherbot]

Comment 1 by Marko.Silokunnas:

I wrote a patch that adds the Flags field to the header:
https://golang.org/cl/13832043

[mikioh]

Comment 2:

This issue was closed by revision golang/net@c2e426e.

Status changed to Fixed.