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MIF IETF MIF working group defines the multiple provisioning domain architecture. This document proposes API extension for the PvD-aware node to support the MIF PvD architecture. The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119.

IETF MIF working group defines the multiple provisioning domain architecture in draft-ietf-mif-mpvd-arch-10 . It defines three levels of PvD support in API: basic, intermediate and advanced. This document discusses the advanced PvD API for the PvD-aware node.

This section summarize the PvD related API implementations. The purpose of this section is to help analyzing the extension of current API implementation to support PvD architecture.

The basic socket API includes the following: Socket API for a typical server: socket() bind() listen() recvmsg() sendmsg() close() Socket API for a typical client: socket() connect() sendmsg() recvmsg() close() extends the basic socket API to support IPv6. It defines the IPv6 Address Family and Protocol Family and also the socket address structure, socket options etc. defines the advanced sockets API for IPv6. It defines the socket API to access IPv6 specific parameters. For example, the IPv6 raw socket, the API to access IPv6 and extension headers etc. defines the IPv6 socket API extension for source address selection. It can be used to override the default source address selection method as defined in . It defines an address preference flags that used for the source address selection. Developers can use this API to explicitly specify the source address to be used in the communication. Example of use cases of this source address selection API includes applications that supporting Mobile IPv6, IPv6 Privacy Extensions, Cryptographically Generated Addresses etc. It uses per-socket and per-packet flags to implement the source address selection. It adds a new socket option at the IPPROTO_IPV6 level. The new option is called IPV6_ADDR_PREFERENCES. It can be used with setsockopt() and getsockopt() calls to set and get the address selection preferences affecting all packets sent via a given socket.

This section defines the extension of socket API to support PvD architecture as defined in It belongs to the advanced PvD API discussed in section 6.3 of . The extension proposed in this document has the following types of API extension: API to get current PvDs that been provided to the node API to explicitly select a PvD API for DNS resolution There are different design alternatives for the PvD API. Including: Get PvDs and select PvD per-socket. Get PvDs and select PvD per-application. Get PvDs and select PvD per-node. This document propose the per-socket approach since it can provide the maximal flexibility for the application developers to meet all the kinds of use cases.

The following API is used to get the current PvD configuration of the node: getpvdinfo() The definition of this API is: int getpvdinfo(const char *nodename, const char *servname, struct pvdinfo **res); The structure of struct pvdinfo is: struct pvdinfo { int sockaddr * ai_addr; int sockaddr * gateway_addr; int sockaddr * dns_addr; struct addrinfo * ai_next; } The definition of parameters is as follows: nodename and servname: The nodename and servname parameter are pointers to null-terminated strings or NULL. One or both of these parameter must be a non-null pinter. A non-null nodename string can be a node name or a numeric host address string. res: The pvdinfo structure. The result is pointed to res structure.

The following API is used to select the specific PvD. setsockopt() setsockopt(int s, struct * pvdinfo pvd) The struct * pvdinfo pvd is a new parameter that used to specify the preferred PvD. The socket can be set to use the PvD that specified by pvdinfo parameter. All the socket related operation will be bind to this PvD. For example, The connect() API call should use the set of configuration parameters that contained in the pvdinfo (source address, gateway and DNS etc).

getaddrinfo() is the socket API used to resolve the IPv4 and IPv6 address. This document proposes to extend getaddrinfo() socket API to allow it use PvD information as a parameter for DNS resolution. int getaddrinfo( const char * hostname, const char * service, const struct addrinfo * hints,struct * pvdinfo pvd, struct addrinfo ** result ); The DNS resolution should use the DNS server that contained in the PvD parameter.

This document makes no request of IANA.

TBD.

The author would like to thank the PvD API design team.

Sun Microsystems, Inc.