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Dev Scribe
a9382c3a50
Decode networksetup entries once for interface lookup and DNS-target selection. Preserve first-enabled lookup and fail-closed DNS uniqueness as separate policies. Treat only the (*) index as disabled, preserving asterisks and whitespace in enabled service names.
102 lines
3.0 KiB
Go
102 lines
3.0 KiB
Go
package cli
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import (
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"bufio"
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"errors"
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"io"
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"regexp"
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"strings"
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)
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// maxNetworksetupLine bounds one line, so one token fills no memory.
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const maxNetworksetupLine = 64 * 1024
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var serviceOrderEntry = regexp.MustCompile(`^\(([1-9][0-9]*|\*)\) (.+)$`)
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var serviceOrderDeviceName = regexp.MustCompile(`^[A-Za-z][A-Za-z0-9]*$`)
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type networkServiceEntry struct {
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Name, Device string
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Disabled bool
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}
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// scanNetworksetup reads the output line by line under a bounded buffer.
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func scanNetworksetup(r io.Reader) *bufio.Scanner {
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scanner := bufio.NewScanner(r)
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scanner.Buffer(nil, maxNetworksetupLine)
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return scanner
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}
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// parseNetworkServiceOrder decodes networksetup -listnetworkserviceorder.
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// Selection policy belongs to the caller: retain disabled and duplicate-device
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// entries so a DNS writer can reject mappings a first-match reader accepts.
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func parseNetworkServiceOrder(r io.Reader) ([]networkServiceEntry, error) {
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const header = "An asterisk (*) denotes that a network service is disabled."
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scanner := scanNetworksetup(r)
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var entries []networkServiceEntry
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var pending *networkServiceEntry
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headerSeen := false
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for scanner.Scan() {
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line := scanner.Text()
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if strings.TrimSpace(line) == "" {
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continue
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}
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if !headerSeen {
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if strings.TrimSpace(line) != header {
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return nil, errors.New("invalid network service listing")
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}
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headerSeen = true
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continue
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}
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if pending == nil {
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m := serviceOrderEntry.FindStringSubmatch(line)
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if m == nil || strings.ContainsAny(m[2], "\r\n\x00") {
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return nil, errors.New("invalid network service entry")
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}
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// Only the index marks a disabled service. An enabled name may
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// itself start with an asterisk; preserve it and its whitespace.
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pending = &networkServiceEntry{Name: m[2], Disabled: m[1] == "*"}
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continue
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}
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if !strings.HasPrefix(line, "(Hardware Port: ") || !strings.HasSuffix(line, ")") {
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return nil, errors.New("invalid network service device")
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}
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at := strings.LastIndex(line, ", Device: ")
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if at < 0 {
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return nil, errors.New("missing network service device")
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}
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device := line[at+len(", Device: ") : len(line)-1]
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if device != "" && !serviceOrderDeviceName.MatchString(device) {
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return nil, errors.New("invalid network device name")
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}
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pending.Device = device
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entries = append(entries, *pending)
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pending = nil
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}
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if err := scanner.Err(); err != nil {
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return nil, err
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}
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if !headerSeen || pending != nil {
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return nil, errors.New("incomplete network service listing")
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}
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return entries, nil
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}
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// serviceNamesByDevice keeps the first enabled service on each device for
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// interface-name lookup and hardware-port metadata, not DNS-target admission.
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func serviceNamesByDevice(r io.Reader) map[string]string {
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entries, err := parseNetworkServiceOrder(r)
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if err != nil {
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return nil
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}
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names := make(map[string]string)
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for _, entry := range entries {
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if entry.Disabled || entry.Device == "" {
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continue
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}
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if _, seen := names[entry.Device]; !seen {
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names[entry.Device] = entry.Name
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}
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}
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return names
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}
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