| 1 | package guards |
| 2 | |
| 3 | import ( |
| 4 | "go/ast" |
| 5 | "go/parser" |
| 6 | "go/token" |
| 7 | "strconv" |
| 8 | "strings" |
| 9 | "testing" |
| 10 | ) |
| 11 | |
| 12 | // Gate 9 (§12) scans what this app logs through slog. Anything that |
| 13 | // writes somewhere else is not scanned and cannot be — so the rule is |
| 14 | // that nothing else may write. |
| 15 | // |
| 16 | // This is not theoretical. chi's own middleware.Logger builds |
| 17 | // log.New(os.Stdout, "", log.LstdFlags) at package init and writes the |
| 18 | // request line — URL included — straight to stdout, touching neither |
| 19 | // slog nor the log package default. middleware.Recoverer writes the |
| 20 | // panic and stack to os.Stderr the same way. Either one is the most |
| 21 | // natural thing for someone to reach for when adding request logging in |
| 22 | // step 2, and either one would carry an address past a green gate. |
| 23 | const chiMiddleware = "github.com/go-chi/chi/v5/middleware" |
| 24 | |
| 25 | // forbiddenSelectors are names that write outside slog, keyed by IMPORT |
| 26 | // PATH rather than by the identifier they happen to be spelled with. |
| 27 | // os.Stdout/os.Stderr are the raw sinks; the log package's own printers |
| 28 | // go to its default writer, which is not the recorder either. |
| 29 | // |
| 30 | // Keying on the path is what makes `import goos "os"; goos.Stderr` fail |
| 31 | // too. An earlier version compared the identifier to the literal "os", |
| 32 | // which an alias walks straight past — and which also fired on a local |
| 33 | // variable that happened to be named log. |
| 34 | var forbiddenSelectors = map[string]map[string]string{ |
| 35 | "os": { |
| 36 | "Stdout": "writes outside slog, so gate 9 cannot see it", |
| 37 | "Stderr": "writes outside slog, so gate 9 cannot see it", |
| 38 | }, |
| 39 | "log": { |
| 40 | "New": "builds a logger gate 9 cannot capture; use slog", |
| 41 | "Print": "writes to the log default, not slog", |
| 42 | "Printf": "writes to the log default, not slog", |
| 43 | "Println": "writes to the log default, not slog", |
| 44 | "Fatal": "writes to the log default, not slog", |
| 45 | "Fatalf": "writes to the log default, not slog", |
| 46 | }, |
| 47 | } |
| 48 | |
| 49 | // TestNoLogSinkOutsideSlog fails on any non-test file that imports chi's |
| 50 | // middleware package or names a writer gate 9 cannot observe. |
| 51 | // |
| 52 | // cmd/home/main.go is in scope: it is where a stray fmt.Fprintln(os.Stderr) |
| 53 | // would most plausibly land. os.Exit and os.Getenv are untouched by this |
| 54 | // rule — only the two stream variables are named. |
| 55 | func TestNoLogSinkOutsideSlog(t *testing.T) { |
| 56 | root := repoRoot(t) |
| 57 | for _, path := range goFiles(t, root) { |
| 58 | if strings.HasSuffix(path, "_test.go") { |
| 59 | continue |
| 60 | } |
| 61 | rel := relPath(t, root, path) |
| 62 | |
| 63 | for _, imp := range fileImports(t, path) { |
| 64 | if imp == chiMiddleware { |
| 65 | t.Errorf("%s: imports %q, whose Logger writes to os.Stdout and Recoverer to os.Stderr — neither is visible to gate 9", rel, chiMiddleware) |
| 66 | } |
| 67 | } |
| 68 | |
| 69 | fset := token.NewFileSet() |
| 70 | f, err := parser.ParseFile(fset, path, nil, 0) |
| 71 | if err != nil { |
| 72 | t.Fatalf("guards: parse %s: %v", rel, err) |
| 73 | } |
| 74 | |
| 75 | // Local identifier -> import path, so an alias resolves to the |
| 76 | // package it actually names. |
| 77 | local := map[string]string{} |
| 78 | for _, imp := range f.Imports { |
| 79 | ipath, err := strconv.Unquote(imp.Path.Value) |
| 80 | if err != nil { |
| 81 | t.Fatalf("guards: unquote import in %s: %v", rel, err) |
| 82 | } |
| 83 | name := ipath[strings.LastIndex(ipath, "/")+1:] |
| 84 | if imp.Name != nil { |
| 85 | name = imp.Name.Name |
| 86 | } |
| 87 | // A dot-import puts the package's names in file scope |
| 88 | // unqualified, so os.Stderr becomes a bare Stderr with no |
| 89 | // selector to match. Refuse the import rather than try to |
| 90 | // resolve it. |
| 91 | if name == "." { |
| 92 | if _, forbidden := forbiddenSelectors[ipath]; forbidden { |
| 93 | t.Errorf("%s:%d: dot-imports %q, which hides its sinks from this guard", |
| 94 | rel, fset.Position(imp.Pos()).Line, ipath) |
| 95 | } |
| 96 | continue |
| 97 | } |
| 98 | local[name] = ipath |
| 99 | } |
| 100 | |
| 101 | // The separate native CLI returns the approved structured public result. |
| 102 | // Permit only that argument, not other raw writes in the same file. |
| 103 | structuredResult := map[*ast.SelectorExpr]bool{} |
| 104 | if rel == "cmd/oficina/main_linux.go" { |
| 105 | ast.Inspect(f, func(n ast.Node) bool { |
| 106 | call, ok := n.(*ast.CallExpr) |
| 107 | if !ok || len(call.Args) != 2 { |
| 108 | return true |
| 109 | } |
| 110 | fun, ok := call.Fun.(*ast.SelectorExpr) |
| 111 | if !ok || fun.Sel.Name != "Run" { |
| 112 | return true |
| 113 | } |
| 114 | pkg, ok := fun.X.(*ast.Ident) |
| 115 | if !ok || local[pkg.Name] != "amadan.net/oficina/home/internal/provisioner" { |
| 116 | return true |
| 117 | } |
| 118 | sink, ok := call.Args[1].(*ast.SelectorExpr) |
| 119 | if !ok || sink.Sel.Name != "Stdout" { |
| 120 | return true |
| 121 | } |
| 122 | owner, ok := sink.X.(*ast.Ident) |
| 123 | if ok && local[owner.Name] == "os" { |
| 124 | structuredResult[sink] = true |
| 125 | } |
| 126 | return true |
| 127 | }) |
| 128 | } |
| 129 | ast.Inspect(f, func(n ast.Node) bool { |
| 130 | sel, ok := n.(*ast.SelectorExpr) |
| 131 | if !ok { |
| 132 | return true |
| 133 | } |
| 134 | ident, ok := sel.X.(*ast.Ident) |
| 135 | if !ok { |
| 136 | return true |
| 137 | } |
| 138 | ipath, isPackage := local[ident.Name] |
| 139 | if !isPackage { |
| 140 | return true |
| 141 | } |
| 142 | if why, bad := forbiddenSelectors[ipath][sel.Sel.Name]; bad && !structuredResult[sel] { |
| 143 | t.Errorf("%s:%d: %s.%s (%s) — %s", |
| 144 | rel, fset.Position(sel.Pos()).Line, ident.Name, sel.Sel.Name, ipath, why) |
| 145 | } |
| 146 | return true |
| 147 | }) |
| 148 | } |
| 149 | } |
| 150 | |
amadan