linux c socket之GetAddrInfo

/* 
 * File:   GetAddrInfo.c
 * Author: 云守护
 */

#include <stdio.h>
#include <stdlib.h>
#include <limits.h>
#include <stdint.h>
#include <string.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <sys/types.h>
#include <sys/socket.h>

#include "DieWithMessage.h"

void PrintSocketAddress(const struct sockaddr *address, FILE *stream) {
    // Test for address and stream
    if (address == NULL || stream == NULL)
        return;

    void *numericAddress; // Pointer to binary address
    // Buffer to contain result (IPv6 sufficient to hold IPv4)
    char addrBuffer[INET6_ADDRSTRLEN];
    in_port_t port; // Port to print
    // Set pointer to address based on address family
    switch (address->sa_family) {
        case AF_INET:
            numericAddress = &((struct sockaddr_in *) address)->sin_addr;
            port = ntohs(((struct sockaddr_in *) address)->sin_port);
            break;
        case AF_INET6:
            numericAddress = &((struct sockaddr_in6 *) address)->sin6_addr;
            port = ntohs(((struct sockaddr_in6 *) address)->sin6_port);
            break;
        default:
            fputs("[unknown type]", stream); // Unhandled type
            return;
    }
    // Convert binary to printable address
    if (inet_ntop(address->sa_family, numericAddress, addrBuffer,
            sizeof (addrBuffer)) == NULL)
        fputs("[invalid address]", stream); // Unable to convert
    else {
        fprintf(stream, "%s", addrBuffer);
        if (port != 0) // Zero not valid in any socket addr
            fprintf(stream, "-%u", port);
    }
}

int main(int argc, char** argv) {
    if (argc != 3) {
        DieWithUserMessage("param", "<Address/Name> <Port/Service>");
    }
    char* addrString = argv[1];
    char* portString = argv[2];
    //地址信息结构体，单链表结构
    struct addrinfo addrCriteria;
    //结构体置零
    memset(&addrCriteria, 0, sizeof (addrCriteria));
    addrCriteria.ai_family = AF_UNSPEC;
    addrCriteria.ai_socktype = SOCK_STREAM;
    addrCriteria.ai_protocol = IPPROTO_TCP;
        //单链表结构
    struct addrinfo *addrList;
    //获取地址信息
    int retVal = getaddrinfo(addrString, portString, &addrCriteria, &addrList);
    if (retVal != 0)
        DieWithUserMessage("getaddrinfo() failed!", (const char*) gai_strerror(retVal));
    struct addrinfo *addr = addrList;
    while (addr != NULL) {
        //处理地址信息
        PrintSocketAddress(addr->ai_addr, stdout);
        fputc('\n', stdout);
         addr = addr->ai_next;
    }
    freeaddrinfo(addrList);

    return (EXIT_SUCCESS);
}