dashboard, p2p, vendor: visualize peers (#19247)

* dashboard, p2p: visualize peers

* dashboard: change scale to green to red

vendor/github.com/oschwald/maxminddb-golang/reader.go

@@ -0,0 +1,259 @@
+package maxminddb
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"net"
+	"reflect"
+)
+
+const (
+	// NotFound is returned by LookupOffset when a matched root record offset
+	// cannot be found.
+	NotFound = ^uintptr(0)
+
+	dataSectionSeparatorSize = 16
+)
+
+var metadataStartMarker = []byte("\xAB\xCD\xEFMaxMind.com")
+
+// Reader holds the data corresponding to the MaxMind DB file. Its only public
+// field is Metadata, which contains the metadata from the MaxMind DB file.
+type Reader struct {
+	hasMappedFile bool
+	buffer        []byte
+	decoder       decoder
+	Metadata      Metadata
+	ipv4Start     uint
+}
+
+// Metadata holds the metadata decoded from the MaxMind DB file. In particular
+// in has the format version, the build time as Unix epoch time, the database
+// type and description, the IP version supported, and a slice of the natural
+// languages included.
+type Metadata struct {
+	BinaryFormatMajorVersion uint              `maxminddb:"binary_format_major_version"`
+	BinaryFormatMinorVersion uint              `maxminddb:"binary_format_minor_version"`
+	BuildEpoch               uint              `maxminddb:"build_epoch"`
+	DatabaseType             string            `maxminddb:"database_type"`
+	Description              map[string]string `maxminddb:"description"`
+	IPVersion                uint              `maxminddb:"ip_version"`
+	Languages                []string          `maxminddb:"languages"`
+	NodeCount                uint              `maxminddb:"node_count"`
+	RecordSize               uint              `maxminddb:"record_size"`
+}
+
+// FromBytes takes a byte slice corresponding to a MaxMind DB file and returns
+// a Reader structure or an error.
+func FromBytes(buffer []byte) (*Reader, error) {
+	metadataStart := bytes.LastIndex(buffer, metadataStartMarker)
+
+	if metadataStart == -1 {
+		return nil, newInvalidDatabaseError("error opening database: invalid MaxMind DB file")
+	}
+
+	metadataStart += len(metadataStartMarker)
+	metadataDecoder := decoder{buffer[metadataStart:]}
+
+	var metadata Metadata
+
+	rvMetdata := reflect.ValueOf(&metadata)
+	_, err := metadataDecoder.decode(0, rvMetdata, 0)
+	if err != nil {
+		return nil, err
+	}
+
+	searchTreeSize := metadata.NodeCount * metadata.RecordSize / 4
+	dataSectionStart := searchTreeSize + dataSectionSeparatorSize
+	dataSectionEnd := uint(metadataStart - len(metadataStartMarker))
+	if dataSectionStart > dataSectionEnd {
+		return nil, newInvalidDatabaseError("the MaxMind DB contains invalid metadata")
+	}
+	d := decoder{
+		buffer[searchTreeSize+dataSectionSeparatorSize : metadataStart-len(metadataStartMarker)],
+	}
+
+	reader := &Reader{
+		buffer:    buffer,
+		decoder:   d,
+		Metadata:  metadata,
+		ipv4Start: 0,
+	}
+
+	reader.ipv4Start, err = reader.startNode()
+
+	return reader, err
+}
+
+func (r *Reader) startNode() (uint, error) {
+	if r.Metadata.IPVersion != 6 {
+		return 0, nil
+	}
+
+	nodeCount := r.Metadata.NodeCount
+
+	node := uint(0)
+	var err error
+	for i := 0; i < 96 && node < nodeCount; i++ {
+		node, err = r.readNode(node, 0)
+		if err != nil {
+			return 0, err
+		}
+	}
+	return node, err
+}
+
+// Lookup takes an IP address as a net.IP structure and a pointer to the
+// result value to Decode into.
+func (r *Reader) Lookup(ipAddress net.IP, result interface{}) error {
+	if r.buffer == nil {
+		return errors.New("cannot call Lookup on a closed database")
+	}
+	pointer, err := r.lookupPointer(ipAddress)
+	if pointer == 0 || err != nil {
+		return err
+	}
+	return r.retrieveData(pointer, result)
+}
+
+// LookupOffset maps an argument net.IP to a corresponding record offset in the
+// database. NotFound is returned if no such record is found, and a record may
+// otherwise be extracted by passing the returned offset to Decode. LookupOffset
+// is an advanced API, which exists to provide clients with a means to cache
+// previously-decoded records.
+func (r *Reader) LookupOffset(ipAddress net.IP) (uintptr, error) {
+	if r.buffer == nil {
+		return 0, errors.New("cannot call LookupOffset on a closed database")
+	}
+	pointer, err := r.lookupPointer(ipAddress)
+	if pointer == 0 || err != nil {
+		return NotFound, err
+	}
+	return r.resolveDataPointer(pointer)
+}
+
+// Decode the record at |offset| into |result|. The result value pointed to
+// must be a data value that corresponds to a record in the database. This may
+// include a struct representation of the data, a map capable of holding the
+// data or an empty interface{} value.
+//
+// If result is a pointer to a struct, the struct need not include a field
+// for every value that may be in the database. If a field is not present in
+// the structure, the decoder will not decode that field, reducing the time
+// required to decode the record.
+//
+// As a special case, a struct field of type uintptr will be used to capture
+// the offset of the value. Decode may later be used to extract the stored
+// value from the offset. MaxMind DBs are highly normalized: for example in
+// the City database, all records of the same country will reference a
+// single representative record for that country. This uintptr behavior allows
+// clients to leverage this normalization in their own sub-record caching.
+func (r *Reader) Decode(offset uintptr, result interface{}) error {
+	if r.buffer == nil {
+		return errors.New("cannot call Decode on a closed database")
+	}
+	return r.decode(offset, result)
+}
+
+func (r *Reader) decode(offset uintptr, result interface{}) error {
+	rv := reflect.ValueOf(result)
+	if rv.Kind() != reflect.Ptr || rv.IsNil() {
+		return errors.New("result param must be a pointer")
+	}
+
+	_, err := r.decoder.decode(uint(offset), reflect.ValueOf(result), 0)
+	return err
+}
+
+func (r *Reader) lookupPointer(ipAddress net.IP) (uint, error) {
+	if ipAddress == nil {
+		return 0, errors.New("ipAddress passed to Lookup cannot be nil")
+	}
+
+	ipV4Address := ipAddress.To4()
+	if ipV4Address != nil {
+		ipAddress = ipV4Address
+	}
+	if len(ipAddress) == 16 && r.Metadata.IPVersion == 4 {
+		return 0, fmt.Errorf("error looking up '%s': you attempted to look up an IPv6 address in an IPv4-only database", ipAddress.String())
+	}
+
+	return r.findAddressInTree(ipAddress)
+}
+
+func (r *Reader) findAddressInTree(ipAddress net.IP) (uint, error) {
+
+	bitCount := uint(len(ipAddress) * 8)
+
+	var node uint
+	if bitCount == 32 {
+		node = r.ipv4Start
+	}
+
+	nodeCount := r.Metadata.NodeCount
+
+	for i := uint(0); i < bitCount && node < nodeCount; i++ {
+		bit := uint(1) & (uint(ipAddress[i>>3]) >> (7 - (i % 8)))
+
+		var err error
+		node, err = r.readNode(node, bit)
+		if err != nil {
+			return 0, err
+		}
+	}
+	if node == nodeCount {
+		// Record is empty
+		return 0, nil
+	} else if node > nodeCount {
+		return node, nil
+	}
+
+	return 0, newInvalidDatabaseError("invalid node in search tree")
+}
+
+func (r *Reader) readNode(nodeNumber uint, index uint) (uint, error) {
+	RecordSize := r.Metadata.RecordSize
+
+	baseOffset := nodeNumber * RecordSize / 4
+
+	var nodeBytes []byte
+	var prefix uint
+	switch RecordSize {
+	case 24:
+		offset := baseOffset + index*3
+		nodeBytes = r.buffer[offset : offset+3]
+	case 28:
+		prefix = uint(r.buffer[baseOffset+3])
+		if index != 0 {
+			prefix &= 0x0F
+		} else {
+			prefix = (0xF0 & prefix) >> 4
+		}
+		offset := baseOffset + index*4
+		nodeBytes = r.buffer[offset : offset+3]
+	case 32:
+		offset := baseOffset + index*4
+		nodeBytes = r.buffer[offset : offset+4]
+	default:
+		return 0, newInvalidDatabaseError("unknown record size: %d", RecordSize)
+	}
+	return uintFromBytes(prefix, nodeBytes), nil
+}
+
+func (r *Reader) retrieveData(pointer uint, result interface{}) error {
+	offset, err := r.resolveDataPointer(pointer)
+	if err != nil {
+		return err
+	}
+	return r.decode(offset, result)
+}
+
+func (r *Reader) resolveDataPointer(pointer uint) (uintptr, error) {
+	var resolved = uintptr(pointer - r.Metadata.NodeCount - dataSectionSeparatorSize)
+
+	if resolved > uintptr(len(r.buffer)) {
+		return 0, newInvalidDatabaseError("the MaxMind DB file's search tree is corrupt")
+	}
+	return resolved, nil
+}