90 lines
1.7 KiB
Go
90 lines
1.7 KiB
Go
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package vnet
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import (
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"errors"
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"fmt"
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"net"
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"sync"
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"github.com/pion/logging"
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)
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var (
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errHostnameEmpty = errors.New("host name must not be empty")
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errFailedtoParseIPAddr = errors.New("failed to parse IP address")
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)
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type resolverConfig struct {
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LoggerFactory logging.LoggerFactory
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}
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type resolver struct {
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parent *resolver // read-only
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hosts map[string]net.IP // requires mutex
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mutex sync.RWMutex // thread-safe
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log logging.LeveledLogger // read-only
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}
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func newResolver(config *resolverConfig) *resolver {
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r := &resolver{
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hosts: map[string]net.IP{},
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log: config.LoggerFactory.NewLogger("vnet"),
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}
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if err := r.addHost("localhost", "127.0.0.1"); err != nil {
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r.log.Warn("failed to add localhost to resolver")
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}
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return r
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}
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func (r *resolver) setParent(parent *resolver) {
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r.mutex.Lock()
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defer r.mutex.Unlock()
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r.parent = parent
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}
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func (r *resolver) addHost(name string, ipAddr string) error {
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r.mutex.Lock()
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defer r.mutex.Unlock()
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if len(name) == 0 {
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return errHostnameEmpty
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}
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ip := net.ParseIP(ipAddr)
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if ip == nil {
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return fmt.Errorf("%w \"%s\"", errFailedtoParseIPAddr, ipAddr)
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}
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r.hosts[name] = ip
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return nil
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}
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func (r *resolver) lookUp(hostName string) (net.IP, error) {
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ip := func() net.IP {
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r.mutex.RLock()
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defer r.mutex.RUnlock()
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if ip2, ok := r.hosts[hostName]; ok {
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return ip2
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}
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return nil
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}()
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if ip != nil {
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return ip, nil
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}
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// mutex must be unlocked before calling into parent resolver
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if r.parent != nil {
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return r.parent.lookUp(hostName)
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}
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return nil, &net.DNSError{
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Err: "host not found",
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Name: hostName,
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Server: "vnet resolver",
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IsTimeout: false,
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IsTemporary: false,
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}
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}
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