我正在尝试查找主机名的 IP 地址,即 www.google.com
我调用 getaddrinfo() 扫描列表,创建一个原始 ipv4 icmp 套接字,然后将该套接字绑定(bind)到该地址
当我检查在wireshark中发送的数据包时,无论我传递给getaddrinfo()什么主机名,地址都会显示为2.0.0.0
int skt, errno;
struct sockaddr_in addr;
struct addrinfo hints; //prefered addr type(connection)
struct addrinfo * list; //list of addr structs
struct addrinfo * addrptr;//the one i am gonna use
struct in_addr test;
if(servname == NULL){
fprintf(stderr, "No servname!\n");
exit(1);
}
/*
* prefered connection type
*/
bzero(&hints, sizeof(hints));
hints.ai_flags = 0;
hints.ai_family = AF_INET;
hints.ai_socktype = SOCK_RAW;
hints.ai_protocol = IPPROTO_ICMP;
/*get IP*/
if((errno = getaddrinfo(servname, 0, &hints, &list))<0){
fprintf(stderr, "addrinfo error, lookup fail: %s",
gai_strerror(errno));
exit(1);
}
addrptr=list;
//start scanning
while(addrptr){
//start
if((skt = socket(addrptr->ai_family, addrptr->ai_socktype, addrptr->ai_protocol))<0){
perror("socket()");
exit(1);
}
if(skt > 0)
if(connect(skt,addrptr->ai_addr, addrptr->ai_addrlen)==0)
break;
printf("attempt connect\n");
close (skt);
addrptr=addrptr->ai_next;
}
//once IP has been found set destination address an port=0
dstaddr.sin_addr.s_addr = ((struct in_addr *)addrptr->ai_addr)->s_addr;
dstaddr.sin_port = 0;
最佳答案
您的代码中似乎存在一些错误:
-
addrptr=list->ai_next
应该是addrptr=addr->ai_next
遍历列表。 - 在 while 循环之后,
addrptr->ai_addr
保存最后找到的条目,而不是list->ai_addr
. -
bind()
成功时返回零,因此您应该检查if(bind(...) == 0) break;
- 除非我弄错了,
bind()
用于将套接字绑定(bind)到本地地址。 要检查是否可以在某个地址访问主机,请使用connect()
相反。
这是我尝试过的代码:
int main(int argc, const char * argv[])
{
int skt, errno;
struct addrinfo hints; //prefered addr type(connection)
struct addrinfo * list; //list of addr structs
struct addrinfo * addrptr;//the one i am gonna use
char *servname = "www.google.com";
memset(&hints, 0, sizeof(hints));
hints.ai_flags = 0;
hints.ai_family = AF_INET;
hints.ai_socktype = SOCK_RAW;
hints.ai_protocol = IPPROTO_ICMP;
if ((errno = getaddrinfo(servname, 0, &hints, &list))<0){
fprintf(stderr, "addrinfo error, lookup fail: %s", gai_strerror(errno));
exit(1);
}
for (addrptr = list; addrptr != NULL; addrptr = addrptr->ai_next) {
if ((skt = socket(addrptr->ai_family, addrptr->ai_socktype, addrptr->ai_protocol)) == -1)
continue;
if(connect(skt,addrptr->ai_addr, addrptr->ai_addrlen) == 0)
break;
close (skt);
}
if (addrptr != NULL) {
char host[NI_MAXHOST];
getnameinfo(addrptr->ai_addr, addrptr->ai_addrlen, host, sizeof(host), NULL, 0, NI_NUMERICHOST);
printf("%s can be reached at %s\n", servname, host);
}
return 0;
}
输出为:“可通过 173.194.113.146 访问 www.google.com”
更新:您复制找到的地址的代码是错误的,应该是
struct sockaddr_in dstaddr;
memcpy(&dstaddr, addrptr->ai_addr, sizeof(dstaddr));
dstaddr.sin_port = 0;
关于c - getaddrinfo() 返回 2.0.0.0,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/20163640/