[历史归档]本文原发布于 cstriker1407.info 个人博客内容为历史存档仅供参考。发布时间2019-08-21 标题使用DNS函数获取IP地址简单代码笔记分类编程 / C C 标签CC·gethostbyname·getaddrinfo使用DNS函数获取IP地址简单代码笔记话不多说在网络编程中我们一般都要对域名进行DNS解析解析函数一般都是gethostbyname但是这个函数已经被过时了而且有多线程风险现在官方建议使用getaddrinfo那么这里我们就简单笔记下如何使用这2个API#includestdio.h#includearpa/inet.h#includenetdb.h#defineLOGprintfvoidtest_gethostbyname(constchar*p_hostname){LOG(test gethostbyname begin--);char**pptrNULL;structhostent*hptrNULL;if((hptrgethostbyname(p_hostname))NULL){LOG(gethostbyname error.errno:%d error:%s ,h_errno,hstrerror(h_errno));return;}LOG(h_name:%s ,hptr-h_name);LOG(h_aliases:);for(pptrhptr-h_aliases;*pptr!NULL;pptr)LOG( alias:%s ,*pptr);LOG(h_length:%d ,hptr-h_length);LOG(h_addrtype:%d ,hptr-h_addrtype);switch(hptr-h_addrtype){caseAF_INET:{LOG(h_addr_list:);for(pptrhptr-h_addr_list;*pptr!NULL;pptr){charstr[INET_ADDRSTRLEN]{0};LOG( addr:%s ,inet_ntop(hptr-h_addrtype,*pptr,str,sizeof(str)));}break;}default:{LOG(unknown h_addrtype:%d ,hptr-h_addrtype);break;}}LOG(test gethostbyname finish--);}voidtest_getaddrinfo(constchar*p_hostname){LOG(test getaddrinfo begin--);intresult_code0;structaddrinfohints,*addr_list,*cur;memset(hints,0,sizeof(hints));hints.ai_familyAF_UNSPEC;hints.ai_socktype0;// SOCK_STREAM OR SOCK_DGRAMhints.ai_protocol0;// IPPROTO_TCP OR IPPROTO_UDPhints.ai_flags0;if((result_codegetaddrinfo(p_hostname,NULL,hints,addr_list))!0){LOG(getaddrinfo error.result:%d error:%s ,result_code,gai_strerror(result_code));return;}LOG(addr_list:);for(curaddr_list;cur!NULL;curcur-ai_next){LOG();LOG( ai_flags:%d ,cur-ai_flags);LOG( ai_family:%d ,cur-ai_family);LOG( ai_socktype:%d ,cur-ai_socktype);LOG( ai_protocol:%d ,cur-ai_protocol);LOG( ai_addrlen:%d ,cur-ai_addrlen);structsockaddr_in*addr(structsockaddr_in*)cur-ai_addr;charstr[INET_ADDRSTRLEN]{0};LOG( ai_addr:%s ,inet_ntop(cur-ai_family,addr-sin_addr,str,sizeof(str)));LOG( ai_canonname:%s ,cur-ai_canonname);LOG();}freeaddrinfo(addr_list);LOG(test getaddrinfo finish--);}voidtest_dns(constchar*p_hostname){LOG(test hostname:%s ,p_hostname);test_gethostbyname(p_hostname);test_getaddrinfo(p_hostname);}intmain(intargc,char*argv[]){test_dns(argv[1]);return0;}