本文介绍了如何快速将sockadd转换为sockaddr_in的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
var sa_tab:[sockaddr?] = [sockaddr](repeating: sockaddr(), count: Int(RTAX_MAX))
let addr:sockaddr = sa_tab[Int(RTAX_DST)]!
let addr_in:sockaddr_in = unsafeBitCast(addr.self, to: UnsafeMutablePointer<sockaddr_in>.self).pointee
m在第三行崩溃，在不同大小的类型之间不能unsafeBitCast
这是完整的方法。 / p>
Here is the complete method.
func ROUNDUP(a:Int) -> Int{
if (a) > 0 {
return (1 + (((a) - 1) | (MemoryLayout<CLong>.size - 1)))
}
else{
return MemoryLayout<CLong>.size
}
}
class func defaultGatewayAddress() -> Int{
var addressIntValue:UInt32 = 0
var mib:[Int32] = [CTL_NET, PF_ROUTE, 0, AF_INET, NET_RT_FLAGS, RTF_GATEWAY]
let l = UnsafeMutablePointer<Int>.allocate(capacity: MemoryLayout<Int>.size)
var buf: UnsafeMutablePointer<CChar>?
var p: UnsafeMutablePointer<CChar>?
var rt: UnsafeMutablePointer<rt_msghdr>?
var sa:UnsafeMutablePointer<sockaddr>?
var sa_tab:[sockaddr?] = [sockaddr](repeating: sockaddr(), count: Int(RTAX_MAX))
var _:Int
var r:Int = -1
if(sysctl(&mib, u_int(mib.count), nil, l, nil, 0) < 0) {
return -1;
}
print(Int8.max)
print(Int8.min)
if(l.pointee > 0) {
buf = UnsafeMutablePointer<CChar>.allocate(capacity: l.pointee)
if(sysctl(&mib, u_int(mib.count), buf, l, nil, 0) < 0) {
return -1;
}
p = buf
let maxBuf = buf!.advanced(by: l.pointee)
while (p! < maxBuf) {
rt = p!.withMemoryRebound(to: rt_msghdr.self, capacity: 1, {$0})
sa = rt!.advanced(by: 1).withMemoryRebound(to: sockaddr.self, capacity: 1, {$0})
for i in 0..<RTAX_MAX {
if (rt!.pointee.rtm_addrs & (1 << i)) == 1{
print("insert \(sa!.pointee) at \(i)")
sa_tab.insert(sa!.pointee, at: Int(i))
sa = sa!.advanced(by: ROUNDUP(a: Int(sa!.pointee.sa_len)))
}
else{
sa_tab.insert(nil, at: Int(i))
}
if ((rt!.pointee.rtm_addrs & (RTA_DST|RTA_GATEWAY)) == (RTA_DST|RTA_GATEWAY)) &&
(sa_tab[Int(RTAX_DST)]?.sa_family == sa_family_t(AF_INET)) &&
(sa_tab[Int(RTAX_GATEWAY)]?.sa_family == sa_family_t(AF_INET)){
var addr:sockaddr = sa_tab[Int(RTAX_DST)]!
let addr_in:sockaddr_in = withUnsafePointer(to: &addr) {
$0.withMemoryRebound(to: sockaddr_in.self, capacity: 1) {
$0.pointee
}
}
if addr_in.sin_addr.s_addr == 0 {
var buffer = [CChar](repeating: CChar(0), count: Int(IFNAMSIZ) + 1)
let result = if_indextoname(UInt32((rt?.pointee.rtm_index)!), &buffer)
var char = "en0".cString(using: .utf8)
#if arch(i386) || arch(x86_64)
// This is a Simulator not an idevice
char = "en1".cString(using: .utf8)
#endif
if(strcmp(result, char) == 0){
r = 0
var gatewayAddr:sockaddr = sa_tab[Int(RTAX_GATEWAY)]!
let gatewayAddr_in:sockaddr_in = withUnsafePointer(to: &gatewayAddr) {
$0.withMemoryRebound(to: sockaddr_in.self, capacity: 1) {
$0.pointee
}
}
addressIntValue = gatewayAddr_in.sin_addr.s_addr
}
}
}
}
p = p?.advanced(by: Int((rt?.pointee.rtm_msglen)!))
}
buf!.deallocate(capacity: l.pointee)
let gatewayLongAddress:UInt32 = addressIntValue
print("gatewayLongAddress: \(gatewayLongAddress)")
let gatewayIPAddress = String(format:"%d.%d.%d.%d", (gatewayLongAddress & 0xFF),
((gatewayLongAddress >> 8) & 0xFF),
((gatewayLongAddress >> 16) & 0xFF),
((gatewayLongAddress >> 24) & 0xFF))
print("gatewayIPAddress: \(gatewayIPAddress)")
}
return Int(addressIntValue)
}
推荐答案
您必须输入 addr 地址 $ c>（要求
addr 是变量），使用 withMemoryRebound（）到
暂时将其重新绑定到 sockaddr_in 指针，然后可以将
取消引用：
You have to take the address of addr (which requiresaddr to be a variable), use withMemoryRebound() totemporarily rebind it to an sockaddr_in pointer, which can thenbe dereferenced:
var addr: sockaddr = ...
let addr_in = withUnsafePointer(to: &addr) {
$0.withMemoryRebound(to: sockaddr_in.self, capacity: 1) {
$0.pointee
}
}
您的 defaultGatewayAddress（ ）方法：
-
sa = sa！.advanced（作者：ROUNDUP（a ：Int（sa！.pointee.sa_len）））使sa前进
sa_len乘以sockaddr的大小，这不是您想要的。 - 测试
if （（（rt！.pointee.rtm_addrs& （RTA_DST | RTA_GATEWAY））==（RTA_DST | RTA_GATEWAY））
必须在之后在0中为i的之后完成。 ; RTAX_MAX循环。 - 带有
sa_tab.insert（sa！.pointee，at：Int（i））将插入新元素到
数组中，而不是替换它们。
sa = sa!.advanced(by: ROUNDUP(a: Int(sa!.pointee.sa_len)))advancessabysa_lenmultiplied with the size ofsockaddr, which is not what you intend.- The test
if ((rt!.pointee.rtm_addrs & (RTA_DST|RTA_GATEWAY)) == (RTA_DST|RTA_GATEWAY))must be done after thefor i in 0..<RTAX_MAXloop. - With
sa_tab.insert(sa!.pointee, at: Int(i))you insert new elements into thearray instead of replacing them.
还请注意
rt = p!.withMemoryRebound(to: rt_msghdr.self, capacity: 1, {$0})
可以在这里工作，但是通常不安全： $ 0 指针仅对执行关闭操作的
有效，并且不得传递给外部。
might work here, but it generally unsafe: The $0 pointer is only valid forthe execution of the closure and must not be passed to the outside.
这是您的代码的有效版本。它实质上是
的翻译
到Swift（反过来，它似乎建立在）。
Here is a working version of your code. It is essentially a translation ofHow can I determine the default gateway on iPhone?to Swift (which in turn seems it built on https://github.com/getlantern/libnatpmp/blob/master/getgateway.c).
我也对其进行了一些简化，并进行了修改，以避免所有强制拆包。
I have also simplified it a bit and modified to avoid all forced unwraps.
func defaultGatewayAddress() -> in_addr? {
var defaultGateway: in_addr?
var mib:[Int32] = [CTL_NET, PF_ROUTE, 0, AF_INET, NET_RT_FLAGS, RTF_GATEWAY]
var len = 0
if sysctl(&mib, u_int(mib.count), nil, &len, nil, 0) < 0 {
return nil
}
let buffer = UnsafeMutablePointer<CChar>.allocate(capacity: len)
defer {
buffer.deallocate(capacity: len)
}
if sysctl(&mib, u_int(mib.count), buffer, &len, nil, 0) < 0 {
return nil
}
var sa_tab = [UnsafePointer<sockaddr>?](repeating: nil, count: Int(RTAX_MAX))
var ptr = buffer
while ptr < buffer + len {
ptr.withMemoryRebound(to: rt_msghdr.self, capacity: 1) { rt in
var sa = UnsafeMutableRawPointer(rt + 1).assumingMemoryBound(to: sockaddr.self)
for i in 0..<RTAX_MAX {
if rt.pointee.rtm_addrs & (1 << i) != 0 {
sa_tab[Int(i)] = UnsafePointer(sa)
sa = (UnsafeMutableRawPointer(sa) + Int(sa.pointee.sa_len)).assumingMemoryBound(to: sockaddr.self)
} else {
sa_tab[Int(i)] = nil
}
}
if let dst = sa_tab[Int(RTAX_DST)],
dst.pointee.sa_family == sa_family_t(AF_INET),
let gateway = sa_tab[Int(RTAX_GATEWAY)],
gateway.pointee.sa_family == sa_family_t(AF_INET)
{
dst.withMemoryRebound(to: sockaddr_in.self, capacity: 1) { addr in
if addr.pointee.sin_addr.s_addr == 0 {
var name = [CChar](repeating: CChar(0), count: Int(IFNAMSIZ) + 1)
if_indextoname(UInt32((rt.pointee.rtm_index)), &name)
if String(cString: name) == "en0" {
defaultGateway = gateway.withMemoryRebound(to: sockaddr_in.self, capacity: 1) {
$0.pointee.sin_addr
}
}
}
}
}
ptr += Int(rt.pointee.rtm_msglen)
}
}
return defaultGateway
}
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