Golang Addrinfo.Ai_flags方法代码示例

func cgoLookupIPCNAME(name string) (addrs []IP, cname string, err error, completed bool) {
	var res *syscall.Addrinfo
	var hints syscall.Addrinfo

	// NOTE(rsc): In theory there are approximately balanced
	// arguments for and against including AI_ADDRCONFIG
	// in the flags (it includes IPv4 results only on IPv4 systems,
	// and similarly for IPv6), but in practice setting it causes
	// getaddrinfo to return the wrong canonical name on Linux.
	// So definitely leave it out.
	hints.Ai_flags = int32((syscall.AI_ALL | syscall.AI_V4MAPPED | syscall.AI_CANONNAME) & cgoAddrInfoMask())

	h := syscall.StringBytePtr(name)
	syscall.Entersyscall()
	gerrno := libc_getaddrinfo(h, nil, &hints, &res)
	syscall.Exitsyscall()
	if gerrno != 0 {
		var str string
		if gerrno == syscall.EAI_NONAME {
			str = noSuchHost
		} else if gerrno == syscall.EAI_SYSTEM {
			str = syscall.GetErrno().Error()
		} else {
			str = bytePtrToString(libc_gai_strerror(gerrno))
		}
		return nil, "", &DNSError{Err: str, Name: name}, true
	}
	defer libc_freeaddrinfo(res)
	if res != nil {
		cname = bytePtrToString((*byte)(unsafe.Pointer(res.Ai_canonname)))
		if cname == "" {
			cname = name
		}
		if len(cname) > 0 && cname[len(cname)-1] != '.' {
			cname += "."
		}
	}
	for r := res; r != nil; r = r.Ai_next {
		// Everything comes back twice, once for UDP and once for TCP.
		if r.Ai_socktype != syscall.SOCK_STREAM {
			continue
		}
		switch r.Ai_family {
		default:
			continue
		case syscall.AF_INET:
			sa := (*syscall.RawSockaddrInet4)(unsafe.Pointer(r.Ai_addr))
			addrs = append(addrs, copyIP(sa.Addr[:]))
		case syscall.AF_INET6:
			sa := (*syscall.RawSockaddrInet6)(unsafe.Pointer(r.Ai_addr))
			addrs = append(addrs, copyIP(sa.Addr[:]))
		}
	}
	return addrs, cname, nil, true
}

func cgoLookupIPCNAME(name string) (addrs []IP, cname string, err error, completed bool) {
	var res *syscall.Addrinfo
	var hints syscall.Addrinfo

	hints.Ai_flags = int32(cgoAddrInfoFlags())
	hints.Ai_socktype = syscall.SOCK_STREAM

	h := syscall.StringBytePtr(name)
	syscall.Entersyscall()
	gerrno := libc_getaddrinfo(h, nil, &hints, &res)
	syscall.Exitsyscall()
	if gerrno != 0 {
		var str string
		if gerrno == syscall.EAI_NONAME {
			str = noSuchHost
		} else if gerrno == syscall.EAI_SYSTEM {
			str = syscall.GetErrno().Error()
		} else {
			str = bytePtrToString(libc_gai_strerror(gerrno))
		}
		return nil, "", &DNSError{Err: str, Name: name}, true
	}
	defer libc_freeaddrinfo(res)
	if res != nil {
		cname = bytePtrToString((*byte)(unsafe.Pointer(res.Ai_canonname)))
		if cname == "" {
			cname = name
		}
		if len(cname) > 0 && cname[len(cname)-1] != '.' {
			cname += "."
		}
	}
	for r := res; r != nil; r = r.Ai_next {
		// We only asked for SOCK_STREAM, but check anyhow.
		if r.Ai_socktype != syscall.SOCK_STREAM {
			continue
		}
		switch r.Ai_family {
		default:
			continue
		case syscall.AF_INET:
			sa := (*syscall.RawSockaddrInet4)(unsafe.Pointer(r.Ai_addr))
			addrs = append(addrs, copyIP(sa.Addr[:]))
		case syscall.AF_INET6:
			sa := (*syscall.RawSockaddrInet6)(unsafe.Pointer(r.Ai_addr))
			addrs = append(addrs, copyIP(sa.Addr[:]))
		}
	}
	return addrs, cname, nil, true
}

func cgoLookupIPCNAME(name string) (addrs []IPAddr, cname string, err error, completed bool) {
	acquireThread()
	defer releaseThread()

	var hints syscall.Addrinfo
	hints.Ai_flags = int32(cgoAddrInfoFlags)
	hints.Ai_socktype = syscall.SOCK_STREAM

	h := syscall.StringBytePtr(name)
	var res *syscall.Addrinfo
	syscall.Entersyscall()
	gerrno := libc_getaddrinfo(h, nil, &hints, &res)
	syscall.Exitsyscall()
	if gerrno != 0 {
		switch gerrno {
		case syscall.EAI_SYSTEM:
			errno := syscall.GetErrno()
			if errno == 0 {
				// err should not be nil, but sometimes getaddrinfo returns
				// gerrno == C.EAI_SYSTEM with err == nil on Linux.
				// The report claims that it happens when we have too many
				// open files, so use syscall.EMFILE (too many open files in system).
				// Most system calls would return ENFILE (too many open files),
				// so at the least EMFILE should be easy to recognize if this
				// comes up again. golang.org/issue/6232.
				errno = syscall.EMFILE
			}
			err = errno
		case syscall.EAI_NONAME:
			err = errNoSuchHost
		default:
			err = addrinfoErrno(gerrno)
		}
		return nil, "", &DNSError{Err: err.Error(), Name: name}, true
	}
	defer libc_freeaddrinfo(res)

	if res != nil {
		cname = bytePtrToString((*byte)(unsafe.Pointer(res.Ai_canonname)))
		if cname == "" {
			cname = name
		}
		if len(cname) > 0 && cname[len(cname)-1] != '.' {
			cname += "."
		}
	}
	for r := res; r != nil; r = r.Ai_next {
		// We only asked for SOCK_STREAM, but check anyhow.
		if r.Ai_socktype != syscall.SOCK_STREAM {
			continue
		}
		switch r.Ai_family {
		case syscall.AF_INET:
			sa := (*syscall.RawSockaddrInet4)(unsafe.Pointer(r.Ai_addr))
			addr := IPAddr{IP: copyIP(sa.Addr[:])}
			addrs = append(addrs, addr)
		case syscall.AF_INET6:
			sa := (*syscall.RawSockaddrInet6)(unsafe.Pointer(r.Ai_addr))
			addr := IPAddr{IP: copyIP(sa.Addr[:]), Zone: zoneToString(int(sa.Scope_id))}
			addrs = append(addrs, addr)
		}
	}
	return addrs, cname, nil, true
}