155 lines
3.7 KiB
Go
155 lines
3.7 KiB
Go
package iproute2mapping
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import (
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"bufio"
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"errors"
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"fmt"
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"io/fs"
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"os"
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"path/filepath"
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"strconv"
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"strings"
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)
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// Storage for mapping
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var ByName = make(map[int]map[string]int)
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var ById = make(map[int]map[int]string)
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// Mapping types
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const (
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PROTOCOL = iota
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TABLE
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)
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// Mapping file of each type, relative to the directories in roots.
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// A directory <file>.d next to it may hold additional *.conf files.
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var fileNames = map[int]string{
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PROTOCOL: "rt_protos",
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TABLE: "rt_tables",
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}
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// Directories holding the mapping files. Later entries override earlier ones,
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// like iproute2 lets /etc override the distribution defaults in /usr/share.
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var roots = []string{"/usr/share/iproute2", "/etc/iproute2"}
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// Export error-check
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var Errors []error
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func init() {
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for mapType, fileName := range fileNames {
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m := load(roots, fileName)
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ByName[mapType], ById[mapType] = m.byName, m.byId
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Errors = append(Errors, m.errs...)
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}
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}
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type mapping struct {
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byName map[string]int
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byId map[int]string
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errs []error
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}
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// load reads the mapping file and its .d directory from every root.
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// Roots or files that do not exist are skipped, unless none exists at all.
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func load(roots []string, fileName string) *mapping {
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m := &mapping{
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byName: make(map[string]int),
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byId: make(map[int]string),
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}
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found := false
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for _, root := range roots {
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paths := []string{filepath.Join(root, fileName)}
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confs, err := filepath.Glob(filepath.Join(root, fileName+".d", "*.conf"))
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if err != nil {
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m.errs = append(m.errs, err)
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}
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paths = append(paths, confs...)
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for _, path := range paths {
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err := m.readFile(path)
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if errors.Is(err, fs.ErrNotExist) {
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continue
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}
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found = true
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if err != nil {
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m.errs = append(m.errs, fmt.Errorf("failed reading mapping-file '%s': %w", path, err))
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}
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}
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}
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if !found {
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m.errs = append(m.errs, fmt.Errorf("no mapping-file '%s' found in %s", fileName, strings.Join(roots, ", ")))
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}
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return m
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}
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// readFile adds all valid entries of the file to the mapping.
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// Invalid lines are added to the errors and skipped.
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func (m *mapping) readFile(filePath string) error {
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file, err := os.Open(filePath)
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if err != nil {
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return err
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}
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defer file.Close()
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scanner := bufio.NewScanner(file)
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// Go through file line-by-line
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for scanner.Scan() {
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text := strings.TrimSpace(scanner.Text())
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if text == "" || strings.HasPrefix(text, "#") {
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continue
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}
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id, name, err := getMappingFromText(text)
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if err != nil {
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// Only warn as we can continue processing the file
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m.errs = append(m.errs,
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fmt.Errorf("mapping-data invalid in '%s': '%s': %w", filePath, text, err),
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)
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continue
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}
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m.byName[name] = id
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m.byId[id] = name
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}
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return scanner.Err()
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}
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// getMappingFromText parses "<id> <name>" with any whitespace in between.
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// The id is decimal or hexadecimal with a 0x prefix, anything after the name is ignored.
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func getMappingFromText(text string) (int, string, error) {
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data := strings.Fields(text)
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if len(data) < 2 {
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return 0, "", fmt.Errorf("expected '<id> <name>'")
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}
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idStr, base := data[0], 10
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if len(idStr) > 2 && (idStr[:2] == "0x" || idStr[:2] == "0X") {
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idStr, base = idStr[2:], 16
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}
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// 31 bits so that the id also fits into an int on 32-bit platforms
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id, err := strconv.ParseUint(idStr, base, 31)
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if err != nil {
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return 0, "", err
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}
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return int(id), data[1], nil
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}
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// Try getting an id from a name (or a string containing an id) with a specified type
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func TryGetId(mappingType int, name string) (int, error) {
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// Try to convert name to id
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id, err := strconv.Atoi(name)
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if err != nil { // name given -> Convert to id
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var found bool
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id, found = ByName[mappingType][name]
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if !found {
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return 0, fmt.Errorf("no id found from name")
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}
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}
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return id, nil
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}
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