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[英]Is there a function that checks whether a sockaddr* named sptr points to an ipv4 or ipv6 address?
[英]Getting IPV4 address from a sockaddr structure
如何將 IP 地址提取到字符串中? 我找不到告訴我char sa_data[14]
是如何編碼的參考。
inet_ntoa()
適用於 IPv4; inet_ntop()
適用於 IPv4 和 IPv6。
給定一個輸入struct sockaddr *res
,這里有兩個代碼片段(在 macOS 上測試):
#include <arpa/inet.h>
struct sockaddr_in *addr_in = (struct sockaddr_in *)res;
char *s = inet_ntoa(addr_in->sin_addr);
printf("IP address: %s\n", s);
#include <arpa/inet.h>
#include <stdlib.h>
// obviously INET6_ADDRSTRLEN is expected to be larger
// than INET_ADDRSTRLEN, but this may be required in case
// if for some unexpected reason IPv6 is not supported, and
// INET6_ADDRSTRLEN is defined as 0
// but this is not very likely and I am aware of no cases of
// this in practice (editor)
char s[INET6_ADDRSTRLEN > INET_ADDRSTRLEN ? INET6_ADDRSTRLEN : INET_ADDRSTRLEN]
= '\0';
switch(res->sa_family) {
case AF_INET: {
struct sockaddr_in *addr_in = (struct sockaddr_in *)res;
////char s[INET_ADDRSTRLEN] = '\0';
// this is large enough to include terminating null
inet_ntop(AF_INET, &(addr_in->sin_addr), s, INET_ADDRSTRLEN);
break;
}
case AF_INET6: {
struct sockaddr_in6 *addr_in6 = (struct sockaddr_in6 *)res;
////char s[INET6_ADDRSTRLEN] = '\0';
// not sure if large enough to include terminating null?
inet_ntop(AF_INET6, &(addr_in6->sin6_addr), s, INET6_ADDRSTRLEN);
break;
}
default:
break;
}
printf("IP address: %s\n", s);
Emil 的回答是正確的,但我的理解是inet_ntoa
已被棄用,而您應該使用inet_ntop
。 如果您使用的是 IPv4,請將您的struct sockaddr
為sockaddr_in
。 您的代碼將如下所示:
struct addrinfo *res; // populated elsewhere in your code
struct sockaddr_in *ipv4 = (struct sockaddr_in *)res->ai_addr;
char ipAddress[INET_ADDRSTRLEN];
inet_ntop(AF_INET, &(ipv4->sin_addr), ipAddress, INET_ADDRSTRLEN);
printf("The IP address is: %s\n", ipAddress);
查看這個很棒的資源以獲得更多解釋,包括如何對 IPv6 地址執行此操作。
一旦sockaddr
為sockaddr_in
,它就會變成這樣:
struct sockaddr_in {
u_short sin_family;
u_short sin_port;
struct in_addr sin_addr;
char sin_zero[8];
};
您可以將getnameinfo
用於 Windows和Linux 。
假設您有一個很好的(即它的成員具有適當的值) sockaddr*
稱為pSockaddr
:
char clienthost[NI_MAXHOST]; //The clienthost will hold the IP address.
char clientservice[NI_MAXSERV];
int theErrorCode = getnameinfo(pSockaddr, sizeof(*pSockaddr), clienthost, sizeof(clienthost), clientservice, sizeof(clientservice), NI_NUMERICHOST|NI_NUMERICSERV);
if( theErrorCode != 0 )
{
//There was an error.
cout << gai_strerror(e1) << endl;
}else{
//Print the info.
cout << "The ip address is = " << clienthost << endl;
cout << "The clientservice = " << clientservice << endl;
}
鍵入鑄造sockaddr
到sockaddr_in
使用和IPv4的檢索inet_ntoa
char * ip = inet_ntoa(((struct sockaddr_in *)sockaddr)->sin_addr);
以下程序解析給定域:
$ gcc a.c
$ ./a.out google.com
AF_INET: 216.58.214.238
AF_INET6: 2a00:1450:400d:803::200e
$ ./a.out google.com af_inet
AF_INET: 216.58.214.238
ac
:
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <arpa/inet.h>
int
main(int argc, char *argv[])
{
struct addrinfo hints, *res, *cres;
int r;
char s[INET6_ADDRSTRLEN];
memset(&hints, 0, sizeof(hints));
if (argc > 2)
hints.ai_family = AF_INET;
hints.ai_socktype = SOCK_DGRAM;
r = getaddrinfo(argv[1], NULL, &hints, &res);
if (r) {
fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(r));
exit(EXIT_FAILURE);
}
for (cres = res; cres; cres = cres->ai_next) {
switch (cres->ai_family) {
case AF_INET:
inet_ntop(AF_INET, &((struct sockaddr_in *)cres->ai_addr)->sin_addr, s, INET6_ADDRSTRLEN);
printf("AF_INET: %s\n", s);
break;
case AF_INET6:
inet_ntop(AF_INET6, &((struct sockaddr_in6 *)cres->ai_addr)->sin6_addr, s, INET6_ADDRSTRLEN);
printf("AF_INET6: %s\n", s);
break;
}
}
freeaddrinfo(res);
}
另一個例子可以在這里找到。
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