resolve.cpp

这个是网络编程

//
// Common routines for resolving addresses and hostnames
//
// Files:
//      resolve.cpp     - Common routines
//      resolve.h       - Header file for common routines
//
// Description:
//      This file contains common name resolution and name printing
//      routines and is used by many of the samples on this CD.
//
// Compile:
//      See asyncserver.cpp
//
// Usage:
//      See asyncserver.cpp
//
#include <winsock2.h>
#include <ws2tcpip.h>
#include <stdio.h>
#include <stdlib.h>

#include "resolve.h"

//
// Function: PrintAddress
//
// Description:
//    This routine takes a SOCKADDR structure and its length 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;

    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 (strcmp(serv, "0") != 0)
    {
        if (sa->sa_family == AF_INET)
            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;

    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 ( (strlen(host) + strlen(serv) + 1) > (unsigned)addrbuflen)
        return WSAEFAULT;
    if (sa->sa_family == AF_INET)
        sprintf(addrbuf, "%s:%s", host, serv);
    else if (sa->sa_family == AF_INET6)
        sprintf(addrbuf, "[%s]:%s", host, serv);
    else
        addrbuf[0] = '\0';

    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;
    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;
}