[英]Init a `sockaddr` struct with a given IP address in Swift
I playing around with Apple's Reachabilitty
class in Swift. 我在Swift玩Apple的
Reachabilitty
课程。
The web server in my private Wi-Fi runs on http://10.0.0.1
. 我的私人Wi-Fi中的Web服务器运行在
http://10.0.0.1
。 To check its reachability I want to use the following function from Reachability.h
(not the one with hostname): 为了检查它的可达性,我想使用
Reachability.h
的以下函数(不是带有主机名的函数):
/*!
* Use to check the reachability of a given IP address.
*/
+ (instancetype)reachabilityWithAddress:(const struct sockaddr *)hostAddress;
I sockaddr
looks accordingly to socket.h
like this: 我
sockaddr
相应地查找socket.h
像这样:
/*
* [XSI] Structure used by kernel to store most addresses.
*/
struct sockaddr {
__uint8_t sa_len; /* total length */
sa_family_t sa_family; /* [XSI] address family */
char sa_data[14]; /* [XSI] addr value (actually larger) */
};
How can I create a sockaddr
struct with th ip address 10.0.0.1
in Swift? 如何在Swift中使用ip地址
10.0.0.1
创建一个sockaddr
结构?
I already read [ here ] something about UnsafePointer
and UnsafeMutablePointer
and that C arrays (or is it in this case an Objective-C array?) are represented as tuples in Swift, but I still don't know for sure how to work with them. 我已经读过[ 这里 ]关于
UnsafePointer
和UnsafeMutablePointer
东西,那些C数组(或者它在这种情况下是一个Objective-C数组?)在Swift中表示为元组,但我仍然不知道如何使用它们。
You create a sockaddr_in
first: 首先创建一个
sockaddr_in
:
var addr = sockaddr_in()
addr.sin_len = UInt8(MemoryLayout.size(ofValue: addr))
addr.sin_family = sa_family_t(AF_INET)
addr.sin_addr.s_addr = inet_addr("10.0.0.1")
// Alternatively:
inet_pton(AF_INET, "10.0.0.1", &addr.sin_addr)
and then "rebind" it to a sockaddr
pointer, eg 然后将它“重新绑定”到一个
sockaddr
指针,例如
let reachability = withUnsafePointer(to: &addr, {
$0.withMemoryRebound(to: sockaddr.self, capacity: 1) {
SCNetworkReachabilityCreateWithAddress(kCFAllocatorDefault, $0)
}
})
Some explanation: 一些解释:
There are different address types for different address families (such as struct sockaddr_in
for IPv4, struct sockaddr_in6
for IPv6). 有不同的地址类型不同的地址族(如
struct sockaddr_in
对于IPv4, struct sockaddr_in6
对IPv6)。 struct sockaddr
is the “common part”, and many socket functions which take a pointer to a sockaddr
as parameter. struct sockaddr
是“公共部分”,以及许多socket函数,它们将指向sockaddr
的指针作为参数。
In C you can simply cast between the pointers: 在C中你可以简单地在指针之间施放:
struct sockaddr sin;
// ...
struct sockaddr *addrPtr = (struct sockaddr *)&sin;
In Swift that is done more explicitly as “rebinding”. 在Swift中,更明确地将其称为“重新绑定”。 For more information, see
有关更多信息,请参阅
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