On Feb 5, 2011, at 11:12 AM, Hartmut Reuter wrote:
> Derrick Brashear wrote:
>> On Sat, Feb 5, 2011 at 4:09 AM, Jeffrey Hutzelman<[email protected]> wrote:
>>> --On Friday, February 04, 2011 10:14:23 AM -0600 Andrew Deason
>>> <[email protected]> wrote:
>>>
>>>> On Fri, 4 Feb 2011 09:32:53 -0500
>>>> Derrick Brashear<[email protected]> wrote:
>>>>
>>>>> struct UbikInterfaceInfo {
>>>>> afsUUID uuid;
>>>>> struct sockaddr_storage hostAddr[UBIK_MAX_INTERFACE_ADDR];
>>>>> };
>>>>
>>>> I thought struct sockaddr_storage can be different on different
>>>> implementations, and isn't guaranteed to store ~everything, just the
>>>> representations that host supports. This is something I've been a little
>>>> unclear about, actually; is there any existing standard for transmitting
>>>> generalized network addresses across platforms? Or does everyone just
>>>> come up with their own?
>>>
>>> Indeed, sockaddr_storage is an API artifact, and certainly not suitable for
>>> use in an Rx RPC signature. The appropriate thing here is some kind of
>>> discriminated union. We should probably define such a type as an extension
>>> to the "standard" types supported by Rx, rather than doing it in Ubik and
>>> again in VL and again in RXAFSCB and so on and so on.
>>
>> to that end, may i propose that rx define a type e.g.
>> typedef struct
>> {
>> /* The discriminator for the union below. */
>> rx_addrtype_t addr_type;
>> union
>> {
>> /* IPv4 address, in network byte order. */
>> struct in_addr ipv4;
>>
>> /* IPv6 address, in network byte order. */
>> struct in6_addr ipv6;
>> } addr;
>> } rxaddr_t;
>
>
> This will not work because in6_addr is a union and xdr cannot handle unions
> unless you have a switch variable which says which branch of the union should
> be used. 16 bytes are not the same as 4 int32 if you have different endianess!
This is kind of ugly, but might be representable in xdr (which I'm moderately
ignorant of):
typedef struct
{
/* The discriminator for the union below. */
rx_addrtype_t addr_type;
addr char addr_buf[ sizeof(struct in6_addr) ];
} rxaddr_t;
> typedef enum
> {
> /* IPv4 address */
> RX_IPV4 = 0x1,
> /* IPv6 address */
> RX_IPV6 = 0x2
> } rx_addrtype_t;
It would clearly need a couple of helper functions so we could do things like
struct rxaddr_t address;
struct in_addr ipv4addr;
struct in6_addr ipv6addr;
switch ( address.addr_type) {
case RX_IPV4:
addrbuf2ipv4( address, &ipv4addr );
break;
case RX_IPV6:
addrbuf2ipv6( address, &ipv6addr );
break;
default:
whoops();
}
and matching ipv{4,6}addr2addrbuf() functions. In the best of all worlds, these
would be mostly simple calls to memcpy().
Steve_______________________________________________
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