| 1 | package contratest |
| 2 | |
| 3 | import ( |
| 4 | "encoding/hex" |
| 5 | "encoding/json" |
| 6 | "net/http" |
| 7 | "testing" |
| 8 | |
| 9 | "github.com/carlosframework/contra/internal/contra/crypto" |
| 10 | ) |
| 11 | |
| 12 | // Compare-and-swap on item writes. |
| 13 | // |
| 14 | // The failure this prevents is silent and total: two writers both open |
| 15 | // version 3, both edit, both write version 4, and the second erases the first |
| 16 | // with nothing anywhere recording that an edit ever existed. On one device it |
| 17 | // cannot happen. With a second device — or a second member of a shared vault |
| 18 | // — it is the ordinary case, which is why this landed before web/8 rather |
| 19 | // than with it. |
| 20 | |
| 21 | func TestTwoWritersDoNotSilentlyOverwriteEachOther(t *testing.T) { |
| 22 | h := newApp(t) |
| 23 | p := provision(t, h, "owner@example.invalid", "a generated test passphrase 8f3a1c") |
| 24 | |
| 25 | itemID := newItemID(t) |
| 26 | if rec := as(t, h, p.cookie, http.MethodPost, "/api/items", |
| 27 | sealItem(t, p, itemID, 1, `{"title":"Original"}`)); rec.Code != http.StatusCreated { |
| 28 | t.Fatalf("create: status %d", rec.Code) |
| 29 | } |
| 30 | |
| 31 | // Two devices have both read version 1 and both composed an edit against |
| 32 | // it. The first one home wins. |
| 33 | first := sealItem(t, p, itemID, 2, `{"title":"Edited by the first device"}`) |
| 34 | second := sealItem(t, p, itemID, 2, `{"title":"Edited by the second device"}`) |
| 35 | |
| 36 | if rec := as(t, h, p.cookie, http.MethodPut, "/api/items", first); rec.Code != http.StatusOK { |
| 37 | t.Fatalf("first write: status %d, body %s", rec.Code, rec.Body.String()) |
| 38 | } |
| 39 | |
| 40 | rec := as(t, h, p.cookie, http.MethodPut, "/api/items", second) |
| 41 | if rec.Code != http.StatusConflict { |
| 42 | t.Fatalf("second write: status %d, want 409 — it overwrote the first", rec.Code) |
| 43 | } |
| 44 | |
| 45 | // And the 409 says what to merge against, so the loser can refetch rather |
| 46 | // than guess whether to resend the same bytes. |
| 47 | var conflict struct { |
| 48 | CurrentVersion uint64 `json:"current_version"` |
| 49 | ItemIDHex string `json:"item_id_hex"` |
| 50 | } |
| 51 | if err := json.Unmarshal(rec.Body.Bytes(), &conflict); err != nil { |
| 52 | t.Fatalf("409 body: %v", err) |
| 53 | } |
| 54 | if conflict.CurrentVersion != 2 { |
| 55 | t.Errorf("409 reported current version %d, want 2", conflict.CurrentVersion) |
| 56 | } |
| 57 | if conflict.ItemIDHex != hex.EncodeToString(itemID) { |
| 58 | t.Errorf("409 named the wrong item") |
| 59 | } |
| 60 | |
| 61 | // The stored item is the FIRST device's edit, intact. |
| 62 | body := openOnlyItem(t, h, p) |
| 63 | if body != `{"title":"Edited by the first device"}` { |
| 64 | t.Errorf("the losing write was not discarded\n got %s", body) |
| 65 | } |
| 66 | } |
| 67 | |
| 68 | // Having lost, the client refetches and writes against what it found. That |
| 69 | // has to succeed, or the conflict is a dead end rather than a retry. |
| 70 | func TestALostWriteSucceedsAfterRefetching(t *testing.T) { |
| 71 | h := newApp(t) |
| 72 | p := provision(t, h, "owner@example.invalid", "a generated test passphrase 8f3a1c") |
| 73 | |
| 74 | itemID := newItemID(t) |
| 75 | as(t, h, p.cookie, http.MethodPost, "/api/items", |
| 76 | sealItem(t, p, itemID, 1, `{"title":"Original"}`)) |
| 77 | as(t, h, p.cookie, http.MethodPut, "/api/items", |
| 78 | sealItem(t, p, itemID, 2, `{"title":"Theirs"}`)) |
| 79 | |
| 80 | // Rejected against the stale version, accepted against the current one. |
| 81 | if rec := as(t, h, p.cookie, http.MethodPut, "/api/items", |
| 82 | sealItem(t, p, itemID, 2, `{"title":"Mine"}`)); rec.Code != http.StatusConflict { |
| 83 | t.Fatalf("stale write: status %d, want 409", rec.Code) |
| 84 | } |
| 85 | if rec := as(t, h, p.cookie, http.MethodPut, "/api/items", |
| 86 | sealItem(t, p, itemID, 3, `{"title":"Mine, merged"}`)); rec.Code != http.StatusOK { |
| 87 | t.Fatalf("merged write: status %d, want 200", rec.Code) |
| 88 | } |
| 89 | if body := openOnlyItem(t, h, p); body != `{"title":"Mine, merged"}` { |
| 90 | t.Errorf("the merged write did not land\n got %s", body) |
| 91 | } |
| 92 | } |
| 93 | |
| 94 | // The client picks the bytes; it does not get to pick the numbering. A gap or |
| 95 | // a repeat means a confused writer, and accepting one would let a client |
| 96 | // reuse a version — which undercuts what binding the version into the AAD is |
| 97 | // for. |
| 98 | func TestItemVersionsMustBeExactlyOneApart(t *testing.T) { |
| 99 | h := newApp(t) |
| 100 | p := provision(t, h, "owner@example.invalid", "a generated test passphrase 8f3a1c") |
| 101 | |
| 102 | itemID := newItemID(t) |
| 103 | as(t, h, p.cookie, http.MethodPost, "/api/items", |
| 104 | sealItem(t, p, itemID, 1, `{"title":"Original"}`)) |
| 105 | |
| 106 | for _, c := range []struct { |
| 107 | what string |
| 108 | expected uint64 |
| 109 | version uint64 |
| 110 | }{ |
| 111 | {"a gap", 1, 5}, |
| 112 | {"no bump at all", 1, 1}, |
| 113 | {"going backwards", 1, 0}, |
| 114 | } { |
| 115 | body := sealItem(t, p, itemID, c.version, `{"title":"x"}`) |
| 116 | body["expected_version"] = c.expected |
| 117 | if rec := as(t, h, p.cookie, http.MethodPut, "/api/items", body); rec.Code == http.StatusOK { |
| 118 | t.Errorf("%s was accepted", c.what) |
| 119 | } |
| 120 | } |
| 121 | } |
| 122 | |
| 123 | // A vault that is not yours answers 404 on the CAS path too. Worth its own |
| 124 | // case because the precondition added a second way to miss, and "somebody |
| 125 | // else wrote first" must never be reported for a row the caller cannot see. |
| 126 | func TestCASDoesNotLeakAnotherAccountsItem(t *testing.T) { |
| 127 | h := newApp(t) |
| 128 | mine := provision(t, h, "owner@example.invalid", "a generated test passphrase 8f3a1c") |
| 129 | theirs := provision(t, h, "other@example.invalid", "a different generated one 4d2e9b") |
| 130 | |
| 131 | itemID := newItemID(t) |
| 132 | as(t, h, mine.cookie, http.MethodPost, "/api/items", |
| 133 | sealItem(t, mine, itemID, 1, `{"title":"Mine"}`)) |
| 134 | |
| 135 | body := sealItem(t, mine, itemID, 2, `{"title":"Theirs now"}`) |
| 136 | if rec := as(t, h, theirs.cookie, http.MethodPut, "/api/items", body); rec.Code != http.StatusNotFound { |
| 137 | t.Errorf("another account's update: status %d, want 404", rec.Code) |
| 138 | } |
| 139 | } |
| 140 | |
| 141 | // openOnlyItem reads the vault's single item back and returns its plaintext, |
| 142 | // so a test asserts on what a client would actually see rather than on a |
| 143 | // status code. |
| 144 | func openOnlyItem(t *testing.T, h http.Handler, p provisioned) string { |
| 145 | t.Helper() |
| 146 | var listed struct { |
| 147 | Items []struct { |
| 148 | ItemIDHex string `json:"item_id_hex"` |
| 149 | Version uint64 `json:"version"` |
| 150 | NonceHex string `json:"nonce_hex"` |
| 151 | CiphertextHex string `json:"ciphertext_hex"` |
| 152 | } `json:"items"` |
| 153 | } |
| 154 | rec := as(t, h, p.cookie, http.MethodGet, |
| 155 | "/api/items?vault="+hex.EncodeToString(p.vaultID), nil) |
| 156 | decode(t, rec, &listed) |
| 157 | if len(listed.Items) != 1 { |
| 158 | t.Fatalf("expected exactly one item, got %d", len(listed.Items)) |
| 159 | } |
| 160 | row := listed.Items[0] |
| 161 | id, _ := hex.DecodeString(row.ItemIDHex) |
| 162 | nonce, _ := hex.DecodeString(row.NonceHex) |
| 163 | ct, _ := hex.DecodeString(row.CiphertextHex) |
| 164 | plain, err := crypto.Open(p.kVault, nonce, |
| 165 | crypto.AAD(p.vaultID, crypto.ObjectItem, id, row.Version), ct) |
| 166 | if err != nil { |
| 167 | t.Fatalf("the stored item does not open: %v", err) |
| 168 | } |
| 169 | unpadded, err := crypto.Unpad(plain) |
| 170 | if err != nil { |
| 171 | t.Fatalf("unpad: %v", err) |
| 172 | } |
| 173 | return string(unpadded) |
| 174 | } |
| 175 | |
amadan