| 1 | package guards |
| 2 | |
| 3 | import ( |
| 4 | "go/ast" |
| 5 | "go/parser" |
| 6 | "go/token" |
| 7 | "strconv" |
| 8 | "testing" |
| 9 | ) |
| 10 | |
| 11 | // sessions.UserID is unusable in this app, and unusable in a way that |
| 12 | // does not announce itself. |
| 13 | // |
| 14 | // It parses the current session's Subject as an integer and returns |
| 15 | // (0, false) when that fails. rastrillo/auth sets Subject to the |
| 16 | // signed-in email address, so the parse fails on EVERY request — UserID |
| 17 | // can never legitimately succeed here. rastrillo's own magic-links page |
| 18 | // calls this "the most expensive mistake you can make with this plugin". |
| 19 | // |
| 20 | // That would be harmless if it errored. It returns 0, and the idiom the |
| 21 | // signature invites is `uid, _ := sessions.UserID(r)`. Dropping the ok |
| 22 | // scopes every subsequent query to user 0: no rows match, so the page |
| 23 | // renders as a plausible empty list rather than failing. Same shape as |
| 24 | // scope.Owned on a team-shared table (AGENTS.md) — both fail as a |
| 25 | // believable answer instead of an error. |
| 26 | // |
| 27 | // Use sessions.Current(r) and its Subject (the address) instead. |
| 28 | // |
| 29 | // This walks the AST for CALL EXPRESSIONS rather than grepping for the |
| 30 | // string. A textual match also hits comments, so the moment this rule is |
| 31 | // explained anywhere in prose the guard needs an exemption — and an |
| 32 | // exemption list is a second thing to maintain that quietly grows until |
| 33 | // it covers the violation it was meant to catch. Docs hit exactly that |
| 34 | // (four warning comments, no call sites) and made the same change. |
| 35 | const ( |
| 36 | sessionsPkg = "amadan.net/rastrillo/rastrillo/sessions" |
| 37 | forbiddenIdent = "UserID" |
| 38 | ) |
| 39 | |
| 40 | func TestNoSessionsUserID(t *testing.T) { |
| 41 | root := repoRoot(t) |
| 42 | for _, path := range goFiles(t, root) { |
| 43 | rel := relPath(t, root, path) |
| 44 | fset := token.NewFileSet() |
| 45 | f, err := parser.ParseFile(fset, path, nil, 0) |
| 46 | if err != nil { |
| 47 | t.Fatalf("guards: parse %s: %v", rel, err) |
| 48 | } |
| 49 | |
| 50 | // Local name for the sessions package in THIS file: it may be |
| 51 | // aliased, dot-imported, or absent. No import, no violation |
| 52 | // possible. |
| 53 | // A dot-import puts UserID in the file scope as a bare |
| 54 | // identifier, so a SelectorExpr check alone would miss it |
| 55 | // entirely. Docs hit exactly that when they took this guard. |
| 56 | local, dotImported := "", false |
| 57 | for _, imp := range f.Imports { |
| 58 | p, err := strconv.Unquote(imp.Path.Value) |
| 59 | if err != nil || p != sessionsPkg { |
| 60 | continue |
| 61 | } |
| 62 | local = "sessions" |
| 63 | if imp.Name != nil { |
| 64 | local = imp.Name.Name |
| 65 | } |
| 66 | if local == "." { |
| 67 | dotImported = true |
| 68 | } |
| 69 | } |
| 70 | if local == "" { |
| 71 | continue |
| 72 | } |
| 73 | |
| 74 | ast.Inspect(f, func(n ast.Node) bool { |
| 75 | call, ok := n.(*ast.CallExpr) |
| 76 | if !ok { |
| 77 | return true |
| 78 | } |
| 79 | switch fn := call.Fun.(type) { |
| 80 | case *ast.SelectorExpr: |
| 81 | pkg, ok := fn.X.(*ast.Ident) |
| 82 | if !ok || pkg.Name != local || fn.Sel.Name != forbiddenIdent { |
| 83 | return true |
| 84 | } |
| 85 | case *ast.Ident: |
| 86 | if !dotImported || fn.Name != forbiddenIdent { |
| 87 | return true |
| 88 | } |
| 89 | default: |
| 90 | return true |
| 91 | } |
| 92 | qualifier, use := local+".", local+".Current(r).Subject" |
| 93 | if dotImported { |
| 94 | qualifier, use = "", "Current(r).Subject" |
| 95 | } |
| 96 | pos := fset.Position(call.Pos()) |
| 97 | t.Errorf("%s:%d: calls %s%s, which returns (0, false) for every "+ |
| 98 | "request in this app because auth's Subject is an email address "+ |
| 99 | "— a dropped ok scopes the query to user 0 and renders as an "+ |
| 100 | "empty list. Use %s.", |
| 101 | rel, pos.Line, qualifier, forbiddenIdent, use) |
| 102 | return true |
| 103 | }) |
| 104 | } |
| 105 | } |
| 106 | |
amadan