Looking at RFC 1918 (which defined the non-routeable address ranges), it says that 10.0.0.0 has a 10/8 prefix which matches what DefaultMask() returns as a mask. But 192.168.0.0 returns FFFFFF00 while the RFC says that it should have a 192.168/16 prefix (FFFF0000) . And 17.16.0.0 returns FFFF0000 while the RFC says that it should have a 17.16/12 prefix (FFF00000). I also don't see the use case for this function. If this is an IP address associated with the current machine, the code should be walking the net interfaces and getting the mask from the OS. If this is an IP address associated with some other machine, why do you need an IP mask? In all of my years programming on the Internet, I never needed to know the mask of a remote machine.
On Saturday, March 2, 2019 at 6:07:22 PM UTC-5, Louki Sumirniy wrote: > > The function is really just looking up the IP prefixes of the > non-routeable address ranges. It has nothing to do with CIDR, it is for > generating a sane default mask when the user has not specified the mask. > > It most definitely should not be deprecated, as these nonrouteable > addresses are definitely not deprecated, and CIDR is an extension, not a > replacement, for IPv4 subnet specification, to give administrators more > flexibliity when configuring multiple address ranges in a fairly large > intranet. > > On Saturday, 2 March 2019 22:32:28 UTC+1, John Dreystadt wrote: >> >> I am new to Go so feel free to point out if I am breaking protocol but I >> ran into the function DefaultMask() in the net package and did some >> research. This function returns the IPMask by assuming that you are using >> IP class A, B, and C addresses. But this concept is from the early days of >> the Internet, and was superseded by CIDR in 1993. See >> https://en.wikipedia.org/wiki/Classless_Inter-Domain_Routing for the >> history here. I looked around both this group and on Stack Overflow to see >> what people had posted about this function. The only reference in >> golang-nuts was to someone using this call to decide if an address was IPv4 >> or not. As the last posting on that thread pointed out, you can use To4() >> for the same purpose (since DefaultMask actually calls To4). The only >> reference on Stack Overflow was someone using it to get the "Next IP >> address". Sorry but I don't understand what he was doing. If you want the >> IPMask for 127.0.0.1, you can just get that interface and get the mask that >> way. I even tried Google for "golang DefaultMask" and only found hits about >> non network things. So I don't believe that this function is useful today >> and should be deprecated, maybe with a message about using To4() if you >> just want to see if an address is IPv4. >> > -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
