Edit

Share via

Compatible Name Resolution for TCP/IP in the Windows Sockets 1.1 API

  • Article

Note

All of the Windows Sockets 1.1 functions for name resolution are specific to IPv4 TCP/IP networks. Application developers are strongly discouraged from continuing to utilize these transport-specific functions that only support IPv4.

 

Application developers should be using the following functions that are protocol-independent and support both IPv6 and IPv4 name resolution.

Windows Sockets 1.1 defined a number of routines used for name resolution with TCP/IP (IP version 4) networks. These are sometimes called the getXbyY functions and include the following:

gethostname
gethostbyaddr
gethostbyname
getprotobyname
getprotobynumber
getservbyname
getservbyport

Asynchronous versions of these functions were also defined.

WSAAsyncGetHostByAddr
WSAAsyncGetHostByName
WSAAsyncGetProtoByName
WSAAsyncGetProtoByNumber
WSAAsyncGetServByName
WSAAsyncGetServByPort

There are also two functions, now implemented in the Winsock2.dll, used to convert dotted Ipv4 address notation to and from string and binary representations, respectively.

inet_addr
inet_ntoa

In order to retain strict backward compatibility with Windows Sockets 1.1, all of the older IPv4-only functions continue to be supported as long as at least one namespace provider is present that supports the AF_INET address family (these functions are not relevant to IP version 6, denoted by AF_INET6).

The Ws2_32.dll implements these compatibility functions in terms of the new, protocol-independent name resolution facilities using an appropriate sequence of WSALookupServiceBegin/Next/End function calls. The details of how the getXbyY functions are mapped to name resolution functions are provided below. The WSs2_32.dll handles the differences between the asynchronous and synchronous versions of the getXbyY functions, so only the implementation of the synchronous getXbyY functions are discussed.

This section describes compatible name resolution for TCP/IP in the Windows Sockets 1.1 API. The following list describes the topics in this section:

Protocol-Independent Name Resolution

Registration and Name Resolution