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bidichk.go
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bidichk.go
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package bidichk
import (
"bytes"
"flag"
"fmt"
"go/token"
"os"
"sort"
"strings"
"unicode/utf8"
"golang.org/x/tools/go/analysis"
)
const (
doc = "bidichk detects dangerous unicode character sequences"
disallowedDoc = `coma separated list of disallowed runes (full name or short name)
Supported runes
LEFT-TO-RIGHT-EMBEDDING, LRE (u+202A)
RIGHT-TO-LEFT-EMBEDDING, RLE (u+202B)
POP-DIRECTIONAL-FORMATTING, PDF (u+202C)
LEFT-TO-RIGHT-OVERRIDE, LRO (u+202D)
RIGHT-TO-LEFT-OVERRIDE, RLO (u+202E)
LEFT-TO-RIGHT-ISOLATE, LRI (u+2066)
RIGHT-TO-LEFT-ISOLATE, RLI (u+2067)
FIRST-STRONG-ISOLATE, FSI (u+2068)
POP-DIRECTIONAL-ISOLATE, PDI (u+2069)
`
)
type disallowedRunes map[string]rune
func (m disallowedRunes) String() string {
ss := make([]string, 0, len(m))
for s := range m {
ss = append(ss, s)
}
sort.Strings(ss)
return strings.Join(ss, ",")
}
func (m disallowedRunes) Set(s string) error {
ss := strings.FieldsFunc(s, func(c rune) bool { return c == ',' })
if len(ss) == 0 {
return nil
}
for k := range m {
delete(m, k)
}
for _, v := range ss {
switch v {
case runeShortNameLRE, runeShortNameRLE, runeShortNamePDF,
runeShortNameLRO, runeShortNameRLO, runeShortNameLRI,
runeShortNameRLI, runeShortNameFSI, runeShortNamePDI:
v = shortNameLookup[v]
fallthrough
case runeNameLRE, runeNameRLE, runeNamePDF,
runeNameLRO, runeNameRLO, runeNameLRI,
runeNameRLI, runeNameFSI, runeNamePDI:
m[v] = runeLookup[v]
default:
return fmt.Errorf("unknown check name %q (see help for full list)", v)
}
}
return nil
}
const (
runeNameLRE = "LEFT-TO-RIGHT-EMBEDDING"
runeNameRLE = "RIGHT-TO-LEFT-EMBEDDING"
runeNamePDF = "POP-DIRECTIONAL-FORMATTING"
runeNameLRO = "LEFT-TO-RIGHT-OVERRIDE"
runeNameRLO = "RIGHT-TO-LEFT-OVERRIDE"
runeNameLRI = "LEFT-TO-RIGHT-ISOLATE"
runeNameRLI = "RIGHT-TO-LEFT-ISOLATE"
runeNameFSI = "FIRST-STRONG-ISOLATE"
runeNamePDI = "POP-DIRECTIONAL-ISOLATE"
runeShortNameLRE = "LRE" // LEFT-TO-RIGHT-EMBEDDING
runeShortNameRLE = "RLE" // RIGHT-TO-LEFT-EMBEDDING
runeShortNamePDF = "PDF" // POP-DIRECTIONAL-FORMATTING
runeShortNameLRO = "LRO" // LEFT-TO-RIGHT-OVERRIDE
runeShortNameRLO = "RLO" // RIGHT-TO-LEFT-OVERRIDE
runeShortNameLRI = "LRI" // LEFT-TO-RIGHT-ISOLATE
runeShortNameRLI = "RLI" // RIGHT-TO-LEFT-ISOLATE
runeShortNameFSI = "FSI" // FIRST-STRONG-ISOLATE
runeShortNamePDI = "PDI" // POP-DIRECTIONAL-ISOLATE
)
var runeLookup = map[string]rune{
runeNameLRE: '\u202A', // LEFT-TO-RIGHT-EMBEDDING
runeNameRLE: '\u202B', // RIGHT-TO-LEFT-EMBEDDING
runeNamePDF: '\u202C', // POP-DIRECTIONAL-FORMATTING
runeNameLRO: '\u202D', // LEFT-TO-RIGHT-OVERRIDE
runeNameRLO: '\u202E', // RIGHT-TO-LEFT-OVERRIDE
runeNameLRI: '\u2066', // LEFT-TO-RIGHT-ISOLATE
runeNameRLI: '\u2067', // RIGHT-TO-LEFT-ISOLATE
runeNameFSI: '\u2068', // FIRST-STRONG-ISOLATE
runeNamePDI: '\u2069', // POP-DIRECTIONAL-ISOLATE
}
var shortNameLookup = map[string]string{
runeShortNameLRE: runeNameLRE,
runeShortNameRLE: runeNameRLE,
runeShortNamePDF: runeNamePDF,
runeShortNameLRO: runeNameLRO,
runeShortNameRLO: runeNameRLO,
runeShortNameLRI: runeNameLRI,
runeShortNameRLI: runeNameRLI,
runeShortNameFSI: runeNameFSI,
runeShortNamePDI: runeNamePDI,
}
type bidichk struct {
disallowedRunes disallowedRunes
}
// NewAnalyzer return a new bidichk analyzer.
func NewAnalyzer() *analysis.Analyzer {
bidichk := bidichk{}
bidichk.disallowedRunes = make(map[string]rune, len(runeLookup))
for k, v := range runeLookup {
bidichk.disallowedRunes[k] = v
}
a := &analysis.Analyzer{
Name: "bidichk",
Doc: doc,
Run: bidichk.run,
}
a.Flags.Init("bidichk", flag.ExitOnError)
a.Flags.Var(&bidichk.disallowedRunes, "disallowed-runes", disallowedDoc)
a.Flags.Var(versionFlag{}, "V", "print version and exit")
return a
}
func (b bidichk) run(pass *analysis.Pass) (interface{}, error) {
var err error
pass.Fset.Iterate(func(f *token.File) bool {
if strings.HasPrefix(f.Name(), "$GOROOT") {
return true
}
return b.check(f.Name(), f.Pos(0), pass) == nil
})
return nil, err
}
func (b bidichk) check(filename string, pos token.Pos, pass *analysis.Pass) error {
body, err := os.ReadFile(filename)
if err != nil {
return err
}
for name, r := range b.disallowedRunes {
start := 0
for {
idx := bytes.IndexRune(body[start:], r)
if idx == -1 {
break
}
start += idx
pass.Reportf(pos+token.Pos(start), "found dangerous unicode character sequence %s", name)
start += utf8.RuneLen(r)
}
}
return nil
}