【转】adns解析库——域名解析实例（C++、linux）

转自：http://blog.csdn.net/fty8788/article/details/7480334

adns是一个开源的dns解析库

官方文档：http://www.chiark.greenend.org.uk/~ian/adns/

1. 初始化

adns_state   adns;
adns_query   query;
adns_answer   *answer;

函数原型：
int adns_init(adns_state *newstate_r, adns_initflags flags, FILE *diagfile /*0=>stderr*/);

举例：
adns_init(&adns, adns_if_noenv, 0);

2. 提交待解析的域名

函数原型：
int adns_submit(adns_state ads,
		const char *owner,
		adns_rrtype type,
		adns_queryflags flags,
		void *context,
		adns_query *query_r);

举例：
adns_submit(adns,   argv[1],   adns_r_a,  (adns_queryflags) 0,   NULL,   &query);

3. 检测是否有域名已检测完成

函数原型：
int adns_check(adns_state ads,
	       adns_query *query_io,
	       adns_answer **answer_r,
	       void **context_r);

例：adns_check(adns,   &query,   &answer,   NULL);

4.

函数原型：
int adns_wait(adns_state ads,
	      adns_query *query_io,
	      adns_answer **answer_r,
	      void **context_r);

例：adns_wait(adns,   &query,   &answer,   NULL);

5. 检测是否已完成所有提交的域名的解析

函数原型：
void adns_finish(adns_state ads);

例：adns_finish(adns);

6. 范例代码（解析IPv4地址可使用adns v1.2或adns v1.4，解析IPv6地址请使用adns v1.6）

可从此处下载：https://github.com/sunada/adns_example/tree/71c9bf8555b67199c6b94c83027fb71eaa0c0241

#include "adns.h"
#include <sys/errno.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>  

int test_dns(char *host)
{
    adns_state ads;
    adns_initflags flags;
    flags = adns_if_nosigpipe | adns_if_noerrprint;
    adns_init(&ads, flags, NULL);  

    adns_query quer = NULL;  

    adns_submit(ads, host, (adns_rrtype) adns_r_a, (adns_queryflags) 0, NULL, &quer);  

    int tryCount = -1;
    int adns_cname = 0;  

    while(tryCount < 32) {
        tryCount += 1;  

        adns_answer *ans;
        int res = adns_check(ads, &quer, &ans, NULL);
        if(res == 0) {
            if (ans->status == adns_s_prohibitedcname) {
                char cname[128];
                strncpy(cname, ans->cname, 127);
                cname[strlen(ans->cname)] = '\0';
                adns_query quer = NULL;
                adns_submit(ads, cname, (adns_rrtype) adns_r_addr, (adns_queryflags) 0, NULL, &quer);
                adns_cname = 1;
            } else {
                //resolve IPv4 address
               /*
　　　　　　　　 * if(adns_cname)
               *     printf("ip: %s\n", ans->status == adns_s_ok ? inet_ntoa(ans->rrs.addr->addr.inet.sin_addr) : "no");
               *     else
               *     printf("ip: %s\n", ans->status == adns_s_ok ? inet_ntoa(*(ans->rrs.inaddr)) : "no");
               */

                //resolve IPv6 address
                if(adns_cname){
                    if(ans->status == adns_s_ok){
                        char buf[INET6_ADDRSTRLEN];
                        inet_ntop(AF_INET6, &ans->rrs.addr->addr.inet6.sin6_addr, buf, sizeof(buf));
                        printf("ip: %s\n", buf);
                    }
                    else{
                         printf("no\n");
                     }
                 }
                 else{
                     if(ans->status == adns_s_ok){
                         char buf[INET6_ADDRSTRLEN];
                         inet_ntop(AF_INET6, ans->rrs.in6addr, buf, sizeof(buf));
                         printf("ip: %s\n", buf);
                     }
                     else{
                          printf("no\n");
                     }
                 }
                 adns_finish(ads);
                 break;
            }
        }
        else if (res == ESRCH || res == EAGAIN) {
            sleep(1);
        } else {
            printf("host(%s) is err!\n", host);
        }
    }
    return 0;
}  

int main(int argc, char *argv[]) {
    char host[128];
    while(1) {
        scanf("%s", host);
        if(strlen(host) == 3 && strcmp(host, "eof")) break;
        test_dns(host);  

    }
    return 0;
}

Makefile

CFLAGS= -g
TARGETS=libadns.a
LIBOBJS=types.o event.o query.o reply.o general.o setup.o transmit.om parse.o poll.o check.o  

all: testdns  

testdns: testdns.c libadns.a
libadns.a: $(LIBOBJS)
                rm -f $@
                $(AR) cq $@ $(LIBOBJS)
clean:
        rm -f $(LIBOBJS) libadns.a *~ config.status  

distclean: clean
        rm -f config.h .depend    

$(LIBOBJS):     adns.h internal.h config.h