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|
package maxminddb
import (
"reflect"
"runtime"
)
type verifier struct {
reader *Reader
}
// Verify checks that the database is valid. It validates the search tree,
// the data section, and the metadata section. This verifier is stricter than
// the specification and may return errors on databases that are readable.
func (r *Reader) Verify() error {
v := verifier{r}
if err := v.verifyMetadata(); err != nil {
return err
}
err := v.verifyDatabase()
runtime.KeepAlive(v.reader)
return err
}
func (v *verifier) verifyMetadata() error {
metadata := v.reader.Metadata
if metadata.BinaryFormatMajorVersion != 2 {
return testError(
"binary_format_major_version",
2,
metadata.BinaryFormatMajorVersion,
)
}
if metadata.BinaryFormatMinorVersion != 0 {
return testError(
"binary_format_minor_version",
0,
metadata.BinaryFormatMinorVersion,
)
}
if metadata.DatabaseType == "" {
return testError(
"database_type",
"non-empty string",
metadata.DatabaseType,
)
}
if len(metadata.Description) == 0 {
return testError(
"description",
"non-empty slice",
metadata.Description,
)
}
if metadata.IPVersion != 4 && metadata.IPVersion != 6 {
return testError(
"ip_version",
"4 or 6",
metadata.IPVersion,
)
}
if metadata.RecordSize != 24 &&
metadata.RecordSize != 28 &&
metadata.RecordSize != 32 {
return testError(
"record_size",
"24, 28, or 32",
metadata.RecordSize,
)
}
if metadata.NodeCount == 0 {
return testError(
"node_count",
"positive integer",
metadata.NodeCount,
)
}
return nil
}
func (v *verifier) verifyDatabase() error {
offsets, err := v.verifySearchTree()
if err != nil {
return err
}
if err := v.verifyDataSectionSeparator(); err != nil {
return err
}
return v.verifyDataSection(offsets)
}
func (v *verifier) verifySearchTree() (map[uint]bool, error) {
offsets := make(map[uint]bool)
it := v.reader.Networks()
for it.Next() {
offset, err := v.reader.resolveDataPointer(it.lastNode.pointer)
if err != nil {
return nil, err
}
offsets[uint(offset)] = true
}
if err := it.Err(); err != nil {
return nil, err
}
return offsets, nil
}
func (v *verifier) verifyDataSectionSeparator() error {
separatorStart := v.reader.Metadata.NodeCount * v.reader.Metadata.RecordSize / 4
separator := v.reader.buffer[separatorStart : separatorStart+dataSectionSeparatorSize]
for _, b := range separator {
if b != 0 {
return newInvalidDatabaseError("unexpected byte in data separator: %v", separator)
}
}
return nil
}
func (v *verifier) verifyDataSection(offsets map[uint]bool) error {
pointerCount := len(offsets)
decoder := v.reader.decoder
var offset uint
bufferLen := uint(len(decoder.buffer))
for offset < bufferLen {
var data interface{}
rv := reflect.ValueOf(&data)
newOffset, err := decoder.decode(offset, rv, 0)
if err != nil {
return newInvalidDatabaseError("received decoding error (%v) at offset of %v", err, offset)
}
if newOffset <= offset {
return newInvalidDatabaseError("data section offset unexpectedly went from %v to %v", offset, newOffset)
}
pointer := offset
if _, ok := offsets[pointer]; ok {
delete(offsets, pointer)
} else {
return newInvalidDatabaseError("found data (%v) at %v that the search tree does not point to", data, pointer)
}
offset = newOffset
}
if offset != bufferLen {
return newInvalidDatabaseError(
"unexpected data at the end of the data section (last offset: %v, end: %v)",
offset,
bufferLen,
)
}
if len(offsets) != 0 {
return newInvalidDatabaseError(
"found %v pointers (of %v) in the search tree that we did not see in the data section",
len(offsets),
pointerCount,
)
}
return nil
}
func testError(
field string,
expected interface{},
actual interface{},
) error {
return newInvalidDatabaseError(
"%v - Expected: %v Actual: %v",
field,
expected,
actual,
)
}
|
