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Add query srv record for server endpoint redirection #4416

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Update dialer.go
  • Loading branch information
Fangliding authored Feb 23, 2025
commit de83d8cb03a7026b2e85602426aa686cd1c653e5
90 changes: 59 additions & 31 deletions transport/internet/dialer.go
Original file line number Diff line number Diff line change
Expand Up @@ -143,49 +143,79 @@ func redirect(ctx context.Context, dst net.Destination, obt string) net.Conn {
return nil
}

// SrvPortOnly = 1;
// SrvAddressOnly = 2;
// SrvPortAndAddress = 3;
// TxtPortOnly = 4;
// TxtAddressOnly = 5;
// TxtPortAndAddress = 6;
func checkDestinationStrategy(ctx context.Context, dest net.Destination, sockopt *SocketConfig) (*net.Destination, error) {
if !dest.Address.Family().IsDomain() || sockopt.DestinationStrategy == DestinationStrategy_TxtPortOnly {
if sockopt.DestinationStrategy == DestinationStrategy_None {
return nil, nil
}
newDest := dest
var OverridePort, OverrideAddress bool
var OverrideBy string
switch sockopt.DestinationStrategy {
case DestinationStrategy_SrvPortOnly:
OverridePort = true
OverrideAddress = false
OverrideBy = "srv"
case DestinationStrategy_SrvAddressOnly:
OverridePort = false
OverrideAddress = true
OverrideBy = "srv"
case DestinationStrategy_SrvPortAndAddress:
OverridePort = true
OverrideAddress = true
OverrideBy = "srv"
case DestinationStrategy_TxtPortOnly:
OverridePort = true
OverrideAddress = false
OverrideBy = "txt"
case DestinationStrategy_TxtAddressOnly:
OverridePort = false
OverrideAddress = true
OverrideBy = "txt"
case DestinationStrategy_TxtPortAndAddress:
OverridePort = true
OverrideAddress = true
OverrideBy = "txt"
default:
return nil, errors.New("unknown DestinationStrategy")
}
// sockopt.DestinationStrategy == DestinationStrategy_TxtPortOnly and skip this ????
// if !dest.Address.Family().IsDomain() || sockopt.DestinationStrategy == DestinationStrategy_TxtPortOnly {

if sockopt.DestinationStrategy == DestinationStrategy_SrvPortOnly ||
sockopt.DestinationStrategy == DestinationStrategy_SrvAddressOnly ||
sockopt.DestinationStrategy == DestinationStrategy_SrvPortAndAddress {
if !dest.Address.Family().IsDomain() {
return nil, nil
}

if OverrideBy == "srv" {
errors.LogDebug(ctx, "query SRV record for "+dest.Address.String())
parts := strings.SplitN(dest.Address.String(), ".", 3)
if len(parts) != 3 {
errors.LogError(ctx, "invalid address format: "+dest.Address.String())
return nil, errors.New("invalid address format")
return nil, errors.New("invalid address format", dest.Address.String())
}
_, srvRecords, err := gonet.DefaultResolver.LookupSRV(context.Background(), parts[0][1:], parts[1][1:], parts[2])
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不走内置 DNS?

if err != nil {
errors.LogError(ctx, "failed to lookup SRV record: "+err.Error())
return nil, err
return nil, errors.New("failed to lookup SRV record").Base(err)
}
for _, srvRecord := range srvRecords {
errors.LogDebug(ctx, "SRV record: "+fmt.Sprintf("addr=%s, port=%d, priority=%d, weight=%d", srvRecord.Target, srvRecord.Port, srvRecord.Priority, srvRecord.Weight))
newDest := dest
if sockopt.DestinationStrategy == DestinationStrategy_SrvPortOnly {
newDest.Port = net.Port(srvRecord.Port)
} else if sockopt.DestinationStrategy == DestinationStrategy_SrvAddressOnly {
newDest.Address = net.ParseAddress(srvRecord.Target)
} else if sockopt.DestinationStrategy == DestinationStrategy_SrvPortAndAddress {
newDest.Address = net.ParseAddress(srvRecord.Target)
newDest.Port = net.Port(srvRecord.Port)
}

return &newDest, nil
errors.LogDebug(ctx, "SRV record: "+fmt.Sprintf("addr=%s, port=%d, priority=%d, weight=%d", srvRecords[0].Target, srvRecords[0].Port, srvRecords[0].Priority, srvRecords[0].Weight))
if OverridePort {
newDest.Port = net.Port(srvRecords[0].Port)
}
} else if sockopt.DestinationStrategy == DestinationStrategy_TxtPortOnly ||
sockopt.DestinationStrategy == DestinationStrategy_TxtAddressOnly ||
sockopt.DestinationStrategy == DestinationStrategy_TxtPortAndAddress {

if OverrideAddress {
newDest.Address = net.ParseAddress(srvRecords[0].Target)
}
return &newDest, nil
}
if OverrideBy == "txt" {
errors.LogDebug(ctx, "query TXT record for "+dest.Address.String())
txtRecords, err := gonet.DefaultResolver.LookupTXT(ctx, dest.Address.String())
if err != nil {
errors.LogError(ctx, "failed to lookup SRV record: "+err.Error())
return nil, err
return nil, errors.New("failed to lookup SRV record").Base(err)
}
for _, txtRecord := range txtRecords {
errors.LogDebug(ctx, "TXT record: "+txtRecord)
Expand All @@ -197,13 +227,11 @@ func checkDestinationStrategy(ctx context.Context, dest net.Destination, sockopt
}

newDest := dest
if sockopt.DestinationStrategy == DestinationStrategy_TxtPortOnly {
if OverridePort {
newDest.Port = port
} else if sockopt.DestinationStrategy == DestinationStrategy_TxtAddressOnly {
newDest.Address = addr
} else if sockopt.DestinationStrategy == DestinationStrategy_TxtPortAndAddress {
}
if OverrideAddress {
newDest.Address = addr
newDest.Port = port
}
return &newDest, nil
}
Expand Down