使用unix套接字获取本地ip地址

Soo，多亏了我在这里得到的建议，我改变了方法，不再试图将机器的主机名解析为IP地址，而是简单地列出所有网络接口及其IP地址。

这是我的代码：

// get the hostname of the server
char hostname[128];
if (gethostname(hostname, sizeof(hostname)) == -1) {
    std::cout << "Could not get the hostname of the server. Error: " << std::strerror(errno) << std::endl;
    return 1;
}
std::cout << "IP addresses for " << hostname << ":" << std::endl << std::endl;
struct ifaddrs *networkInterfaceList, *p;
getifaddrs (&networkInterfaceList); // get information about the network interfaces
// iterate over all the network interfaces we got and try to extract their IP address
for (p = networkInterfaceList; p != NULL; p = p->ifa_next) {
    char serverIPAddress[INET6_ADDRSTRLEN];
    void *addr;
    std::string ipVersion;
    // get the pointer to the address itself,
    // different fields in IPv4 and IPv6:
    if (p->ifa_addr->sa_family == AF_INET) { // IPv4
        struct sockaddr_in *ipv4 = (struct sockaddr_in *)p->ifa_addr;
        addr = &(ipv4->sin_addr);
        ipVersion = "IPv4";
    } else { // IPv6
        struct sockaddr_in6 *ipv6 = (struct sockaddr_in6 *)p->ifa_addr;
        addr = &(ipv6->sin6_addr);
        ipVersion = "IPv6";
    }
    // take the IP address of our hostname and convert it into a readable format
    inet_ntop(p->ifa_addr->sa_family, addr, serverIPAddress, sizeof(serverIPAddress));
    // sometime the IP address is empty so only print if there is one
    if (std::strlen(serverIPAddress) > 0)
        std::cout << "Interface: " << std::setw(6) << std::left << p->ifa_name << " " << ipVersion << ": " << serverIPAddress << std::endl;
}
freeifaddrs(networkInterfaceList); // free the linked list

以防其他人正在尝试类似的东西。

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您将无法获得这样的"全局"IP地址，只能获得本地地址。为了让客户端连接到您，它需要从互联网上可见的全局IP地址，即您的网关（路由器）的IP。这是因为路由器将计算机的IP地址转换为全局可见的IP地址，并将其存储在表中，以便将传入连接正确路由到正确的子网络。这被称为NATing（点击此处了解有关NAT的更多信息）。

如果您希望客户端显式连接到您，则需要向他们提供路由器的IP地址（根据您的操作系统，使用命令行工具），并配置端口转发，以便路由器自动将到达（IP_router，port_router）的数据包转发到（IP_host，port_host）。这是在路由器的配置面板中完成的。根据您的路由器，这将在菜单中的某个位置找到。您可以通过键入类似192.068.0.1或192.168.0.0的内容来连接到路由器。

在Windows上，您可以使用gethostbyname并通过hostent h_addr_list枚举。。。在Linux上，您可以创建一个临时套接字，在SIOCGIFCONF上使用ioctl并通过接口枚举。

我认为在代码的末尾，您滥用了数据结构sockaddr_in。线路：

inet_ntop(AF_INET, &(serverInfo->ai_addr), serverIPAddress, INET_ADDRSTRLEN);

应替换为：

struct sockaddr_in *ipv4 = (struct sockaddr_in *)serverInfo->ai_addr;
void *addr = &(ipv4->sin_addr);
inet_ntop(AF_INET, addr, serverIPAddress, INET_ADDRSTRLEN);

// Get a Vector of the IP addresses of this computer
std::vector<std::string> getIPAddresses() {
    std::vector<std::string> IPAddresses;
    int TempAddress = 0;
    char* TempIPAddress = (char*) malloc(16);
    ifaddrs* ifap = NULL;   //Head of the interface address linked list
    if (getifaddrs(&ifap) == 0 && ifap != NULL) {
        //Get another pointer to move down the linked list
        ifaddrs* current = ifap;
        //Move down the linked list until we get to a NULL pointer
        while (current != NULL) {
            //Create a pointer of the correct type to work with
            const sockaddr_in* interfaceAddress = reinterpret_cast<const sockaddr_in*>(current->ifa_addr);
            if (current->ifa_addr != NULL) {
                if (current->ifa_addr->sa_family == AF_INET) {
                    //printf("%s:", current->ifa_name);
                    if (interfaceAddress != NULL) {
                        TempAddress = ntohl(interfaceAddress->sin_addr.s_addr);
                        sprintf(TempIPAddress, "%d.%d.%d.%d", (TempAddress >> 24) & 0xFF, (TempAddress >> 16) & 0xFF,
                               (TempAddress >> 8) & 0xFF, TempAddress & 0xFF);
                        //Don't include the lookback address
                        if (strcmp(TempIPAddress, "127.0.0.1") != 0) {
                            IPAddresses.push_back(std::string(TempIPAddress));
                        }
                        //printf("%sn", TempIPAddress);
                    }
                }
            }
            //Move to the next node in the linked-list
            current = current->ifa_next;
        }
        //Release the interface memory
        freeifaddrs(ifap);
        ifap = NULL;
    }
    return IPAddresses;
}