Question

我正在尝试使用libmilter开发邮件milter。因此，我必须定义一些回调函数。目前我在使用connect（）函数。声明如下：

sfsistat mlfi_connect(SMFICTX *ctx, char *hostname, struct sockaddr *hostaddr);

当客户端连接到milter时，将调用此回调。现在我想记录主机名，IP和端口。对于主机名，这很容易。但我不能让它与hostaddr合作。

我在StackOverflow上发现了一些类似的文章，但没有一个对我有用。看起来我必须将结构转换为sockaddr_in或sockaddr_in6，但是我遇到编译器问题，例如“成员访问不完整类型'struct sockaddr_in'”

这就是我的尝试：

struct sockaddr_in *sin;
struct sockaddr_in6 *sin6;
string ipandport;

switch (hostaddr->sa_family) {
    case AF_INET:
        sin = (struct sockaddr_in *) hostaddr;
        unsigned char *ip = (unsigned char *)&sin->sin_addr.s_addr;
        break;
    case AF_INET6:
        // TODO
        break;
    default:
        ipandport = "unknown";
}

我从未想过如此难以得到如此微不足道的信息： - ）

Answer 1

IPv4的非编译测试示例。 IPv6几乎相同，只需调整使用的常量定义（阅读inet_ntop手册页）

#include <arpa/inet.h>

void print_ipv4(struct sockaddr *s)
{
 struct sockaddr_in *sin = (struct sockaddr_in *)s;
 char ip[INET_ADDRSTRLEN];
 uint16_t port;

 inet_pton (AF_INET, sin->sin_addr, ip, sizeof (ip));
 port = htons (sin->sin_port);

 printf ("host %s:%d\n", ip, port);
}

Answer 2

我找到了不同的答案。在这里发帖后，我再次搜索，发现了这个，最终对我有用：

sfsistat mlfi_connect(SMFICTX *ctx, char *hostname, struct sockaddr *hostaddr) {
assert(ctx != NULL);
assert(hostaddr != NULL);

string ipandport;

char clienthost[NI_MAXHOST];
char clientport[NI_MAXSERV];
int result = getnameinfo(hostaddr, sizeof(*hostaddr),
                         clienthost, sizeof(clienthost),
                         clientport, sizeof (clientport),
                         NI_NUMERICHOST | NI_NUMERICSERV);

if(result != 0)
    ipandport = "unknown";
else
{
    if (hostaddr->sa_family == AF_INET)
        ipandport = string(clienthost) + ":" + string(clientport);
    else
        ipandport = "[" + string(clienthost) + "]:" + string(clientport);
}

if (hostname == nullptr)
    hostname = const_cast<char *>("unknown");

Client *con = new Client(string(hostname), ipandport);

// Store new client data
smfi_setpriv(ctx, static_cast<void *>(con));

cout << "id=" << con->getId()
        << " connect from " << con->getHostname()
        << " IP and port " << con->getIPandPort() << endl;

return SMFIS_CONTINUE;
}

Answer 3

r := strings.NewReplacer( "January", "Januar", "February", "Februar", "March", "März", "April", "April", "May", "Mai", "June", "Juni", "July", "Juli", "August", "August", "September", "September", "October", "Oktober", "November", "November", "December", "Dezember", ) time := inputTime.Format("2 January 2006") outputString := r.Replace(time)可以从二进制转换为字符串，而不是inet_ntop。

inet_pton

示例：

$ man inet_ntop
...
This  function  converts  the  network address structure src in the af address family into a character string.  The
resulting string is copied to the buffer pointed to by dst, which must be a non-null pointer.  The caller specifies
the number of bytes available in this buffer in the argument size.

Answer 4

struct sockaddr_in  client, server;
SOCKET s , new_socket;
s = socket(AF_INET , SOCK_STREAM , 0 )

server.sin_family       = AF_INET;
server.sin_addr.s_addr  = INADDR_ANY;
server.sin_port         = htons( 8888 );

bind(s ,(struct sockaddr *)&server , sizeof(server))
//pending connection in queue is 1
listen(s , 1);

new_socket = accept(s , (struct sockaddr *)&client, &c);
printf ("client remote port: %i\n", ntohs(client.sin_port) );

C ++ - 如何从struct sockaddr获取IP和端口

4 个答案: