Windows-classic-samples/Samples/Win7Samples/netds/winsock/iphdrinc/resolve.c

//
// Common routines for resolving addresses and hostnames
//
// Files:
//      resolve.c       - Common routines
//      resolve.h       - Header file for common routines
//
// Description:
//      This file contains common name resolution and name printing
//      functions.
// 
// NOTE:
//    From Network Programming for Microsoft Windows, Second Edition 
//    by Anthony Jones and James Ohlund.  Copyright 2002.  
//    Reproduced by permission of Microsoft Press.  All rights reserved. 
//
#include <winsock2.h>
#include <ws2tcpip.h>

// This sample uses the new getaddrinfo/getnameinfo functions which are new to
// Windows XP. To run this sample on older OSes, include the following header
// file which makes it work automagically.
#include <wspiapi.h>

#include <stdio.h>
#include <stdlib.h>

#include "resolve.h"

//
// Function: PrintAddress
//
// Description:
//    This routine takes a SOCKADDR structure and its lenght and prints
//    converts it to a string representation. This string is printed
//    to the console via stdout.
//
int PrintAddress(SOCKADDR *sa, int salen)
{
    char    host[NI_MAXHOST],
            serv[NI_MAXSERV];
    int     hostlen = NI_MAXHOST,
            servlen = NI_MAXSERV,
            rc;

    // Validate argument
    if (sa == NULL)
        return WSAEFAULT;

    rc = getnameinfo(
            sa,
            salen,
            host,
            hostlen,
            serv,
            servlen,
            NI_NUMERICHOST | NI_NUMERICSERV
            );
    if (rc != 0)
    {
        fprintf(stderr, "%s: getnameinfo failed: %d\n", __FILE__, rc);
        return rc;
    }

    // If the port is zero then don't print it
    if (strncmp(serv, "0", 1) != 0)
    {
        if (sa->sa_family == AF_INET6)
            printf("[%s]:%s", host, serv);
        else
            printf("%s:%s", host, serv);
    }
    else
        printf("%s", host);

    return NO_ERROR;
}

//
// Function: FormatAddress
//
// Description:
//    This is similar to the PrintAddress function except that instead of
//    printing the string address to the console, it is formatted into
//    the supplied string buffer.
//
int FormatAddress(SOCKADDR *sa, int salen, char *addrbuf, int addrbuflen)
{
    char    host[NI_MAXHOST],
            serv[NI_MAXSERV];
    int     hostlen = NI_MAXHOST,
            servlen = NI_MAXSERV,
            rc;

    // Validate input
    if ((sa == NULL) || (addrbuf == NULL))
        return WSAEFAULT;

    // Format the name
    rc = getnameinfo(
            sa,
            salen,
            host,
            hostlen,
            serv,
            servlen,
            NI_NUMERICHOST | NI_NUMERICSERV     // Convert to numeric representation
            );
    if (rc != 0)
    {
        fprintf(stderr, "%s: getnameinfo failed: %d\n", __FILE__, rc);
        return rc;
    }
    if ( (strlen(host) + strlen(serv) + 1) > (unsigned)addrbuflen)
        return WSAEFAULT;
    if (strncmp(serv, "0", 1) != 0)
    {
        if (sa->sa_family == AF_INET)
            _snprintf_s(addrbuf, addrbuflen,addrbuflen-1, "%s:%s", host, serv);
        else if (sa->sa_family == AF_INET6)
            _snprintf_s(addrbuf, addrbuflen,addrbuflen-1, "[%s]:%s", host, serv);
        else
            addrbuf[0] = '\0';
    }
    else
    {
        _snprintf_s(addrbuf, addrbuflen,addrbuflen-1, "%s", host);
    }

    return NO_ERROR;
}

//
// Function: ResolveAddress
//
// Description:
//    This routine resolves the specified address and returns a list of addrinfo
//    structure containing SOCKADDR structures representing the resolved addresses.
//    Note that if 'addr' is non-NULL, then getaddrinfo will resolve it whether
//    it is a string listeral address or a hostname.
//
struct addrinfo *ResolveAddress(char *addr, char *port, int af, int type, int proto)
{
    struct addrinfo hints,
    *res = NULL;
    int             rc;

    memset(&hints, 0, sizeof(hints));
    hints.ai_flags  = ((addr) ? 0 : AI_PASSIVE);
    hints.ai_family = af; //((addr) ? AF_UNSPEC : af);
    hints.ai_socktype = type;
    hints.ai_protocol = proto;

    rc = getaddrinfo(
            addr,
            port,
           &hints,
           &res
            );
    if (rc != 0)
    {
        printf("Invalid address %s, getaddrinfo failed: %d\n", addr, rc);
        return NULL;
    }
    return res;
}

//
// Function: ReverseLookup
//
// Description:
//    This routine takes a SOCKADDR and does a reverse lookup for the name
//    corresponding to that address.
//
int ReverseLookup(SOCKADDR *sa, int salen, char *buf, int buflen)
{
    char    host[NI_MAXHOST];
    int     hostlen=NI_MAXHOST,
            rc;
    
    // Validate parameters
    if ((sa == NULL) || (buf == NULL))
        return WSAEFAULT;

    rc = getnameinfo(
            sa,
            salen,
            host,
            hostlen,
            NULL,
            0,
            0
            );
    if (rc != 0)
    {
        fprintf(stderr, "getnameinfo failed: %d\n", rc);
        return rc;
    }

    strncpy_s(buf, buflen,host, buflen-1);

    return NO_ERROR;
}