| 1 | package browser |
| 2 | |
| 3 | import ( |
| 4 | "bytes" |
| 5 | "context" |
| 6 | "encoding/json" |
| 7 | "errors" |
| 8 | "fmt" |
| 9 | "io" |
| 10 | "net/http" |
| 11 | "strings" |
| 12 | "sync" |
| 13 | "time" |
| 14 | ) |
| 15 | |
| 16 | const httpHealthTTL = 30 * time.Second |
| 17 | |
| 18 | // httpExecutor is the JSON-over-HTTP client half of the contract. It never |
| 19 | // retries: a write whose reply was lost is reported as ErrUnknownOutcome, and |
| 20 | // the tools tell the model not to try again. |
| 21 | type httpExecutor struct { |
| 22 | endpoint string |
| 23 | token string |
| 24 | client *http.Client |
| 25 | now func() time.Time |
| 26 | |
| 27 | mu sync.Mutex |
| 28 | healthyAt time.Time |
| 29 | } |
| 30 | |
| 31 | // NewHTTPExecutor returns an Executor that forwards every call to the |
| 32 | // broker at endpoint with a bearer token. A nil client uses |
| 33 | // http.DefaultClient; the caller decides timeouts through ctx. |
| 34 | func NewHTTPExecutor(endpoint, token string, client *http.Client) Executor { |
| 35 | if client == nil { |
| 36 | client = http.DefaultClient |
| 37 | } |
| 38 | return &httpExecutor{ |
| 39 | endpoint: strings.TrimRight(strings.TrimSpace(endpoint), "/"), |
| 40 | token: strings.TrimSpace(token), |
| 41 | client: client, |
| 42 | now: time.Now, |
| 43 | } |
| 44 | } |
| 45 | |
| 46 | // Available reports whether a health probe succeeded within the last 30 s, |
| 47 | // probing again when the cache is cold or expired. |
| 48 | func (e *httpExecutor) Available(ctx context.Context) bool { |
| 49 | e.mu.Lock() |
| 50 | fresh := !e.healthyAt.IsZero() && e.now().Sub(e.healthyAt) < httpHealthTTL |
| 51 | e.mu.Unlock() |
| 52 | if fresh { |
| 53 | return true |
| 54 | } |
| 55 | req, err := e.newRequest(ctx, http.MethodGet, e.endpoint+httpHealthRoute, nil) |
| 56 | if err != nil { |
| 57 | return false |
| 58 | } |
| 59 | resp, err := e.client.Do(req) |
| 60 | if err != nil { |
| 61 | return false |
| 62 | } |
| 63 | _, _ = io.Copy(io.Discard, io.LimitReader(resp.Body, 4<<10)) |
| 64 | _ = resp.Body.Close() |
| 65 | if resp.StatusCode != http.StatusNoContent && resp.StatusCode != http.StatusOK { |
| 66 | return false |
| 67 | } |
| 68 | e.mu.Lock() |
| 69 | e.healthyAt = e.now() |
| 70 | e.mu.Unlock() |
| 71 | return true |
| 72 | } |
| 73 | |
| 74 | func (e *httpExecutor) newRequest(ctx context.Context, method, url string, body []byte) (*http.Request, error) { |
| 75 | req, err := http.NewRequestWithContext(ctx, method, url, bytes.NewReader(body)) |
| 76 | if err != nil { |
| 77 | return nil, err |
| 78 | } |
| 79 | req.Header.Set("Authorization", "Bearer "+e.token) |
| 80 | if body != nil { |
| 81 | req.Header.Set("Content-Type", "application/json") |
| 82 | } |
| 83 | if id := SessionFromContext(ctx); id != "" { |
| 84 | req.Header.Set(SessionHeader, id) |
| 85 | } |
| 86 | return req, nil |
| 87 | } |
| 88 | |
| 89 | // call posts in as JSON to /v1/browser/<method> and decodes the reply into |
| 90 | // out. Transport failures (no HTTP reply at all) come back as errTransport |
| 91 | // so Act can turn them into ErrUnknownOutcome. |
| 92 | func (e *httpExecutor) call(ctx context.Context, method string, in, out any) error { |
| 93 | body, err := json.Marshal(in) |
| 94 | if err != nil { |
| 95 | return fmt.Errorf("browser broker: encode %s: %w", method, err) |
| 96 | } |
| 97 | req, err := e.newRequest(ctx, http.MethodPost, e.endpoint+httpRoutePrefix+method, body) |
| 98 | if err != nil { |
| 99 | return fmt.Errorf("browser broker: %s: %w", method, err) |
| 100 | } |
| 101 | resp, err := e.client.Do(req) |
| 102 | if err != nil { |
| 103 | return &transportError{method: method, err: err} |
| 104 | } |
| 105 | defer resp.Body.Close() |
| 106 | data, err := io.ReadAll(io.LimitReader(resp.Body, httpMaxResponseBytes+1)) |
| 107 | if err != nil { |
| 108 | return &transportError{method: method, err: err} |
| 109 | } |
| 110 | if len(data) > httpMaxResponseBytes { |
| 111 | return fmt.Errorf("browser broker: %s: reply exceeds %d bytes", method, httpMaxResponseBytes) |
| 112 | } |
| 113 | if resp.StatusCode == http.StatusConflict { |
| 114 | return decodeWireError(method, data) |
| 115 | } |
| 116 | if method == "capability" && (resp.StatusCode == http.StatusNotFound || resp.StatusCode == http.StatusNotImplemented) { |
| 117 | return errCapabilityUnsupported |
| 118 | } |
| 119 | if resp.StatusCode != http.StatusOK { |
| 120 | return fmt.Errorf("browser broker: %s: status %d: %s", method, resp.StatusCode, wireMessage(data)) |
| 121 | } |
| 122 | if out == nil { |
| 123 | return nil |
| 124 | } |
| 125 | if err := json.Unmarshal(data, out); err != nil { |
| 126 | return fmt.Errorf("browser broker: decode %s reply: %w", method, err) |
| 127 | } |
| 128 | return nil |
| 129 | } |
| 130 | |
| 131 | var errCapabilityUnsupported = errors.New("capability_unsupported: remote browser enhancement unavailable") |
| 132 | |
| 133 | func (e *httpExecutor) BrowserCapability(ctx context.Context, name string, args json.RawMessage) (json.RawMessage, error) { |
| 134 | var out json.RawMessage |
| 135 | var params struct { |
| 136 | Action string `json:"action"` |
| 137 | } |
| 138 | if err := json.Unmarshal(args, ¶ms); err != nil { |
| 139 | return nil, err |
| 140 | } |
| 141 | in := struct { |
| 142 | Name string `json:"name"` |
| 143 | Args json.RawMessage `json:"args"` |
| 144 | }{name, args} |
| 145 | err := e.call(ctx, "capability", in, &out) |
| 146 | write := name == "pointer" || name == "viewport" && params.Action != "get" || name == "record" && params.Action != "status" |
| 147 | if write && err != nil && !errors.Is(err, errCapabilityUnsupported) && !errors.Is(err, ErrStaleReference) && !errors.Is(err, ErrTakenOver) && !errors.Is(err, ErrNoGrant) && !errors.Is(err, ErrUnknownOutcome) { |
| 148 | err = fmt.Errorf("%w: %w", ErrUnknownOutcome, err) |
| 149 | } |
| 150 | return out, err |
| 151 | } |
| 152 | |
| 153 | type transportError struct { |
| 154 | method string |
| 155 | err error |
| 156 | } |
| 157 | |
| 158 | func (t *transportError) Error() string { return "browser broker: " + t.method + ": " + t.err.Error() } |
| 159 | func (t *transportError) Unwrap() error { return t.err } |
| 160 | |
| 161 | // wireMessage prefers the handler's message over a raw body dump. |
| 162 | func wireMessage(data []byte) string { |
| 163 | var we wireError |
| 164 | if err := json.Unmarshal(data, &we); err == nil && we.Message != "" { |
| 165 | return we.Message |
| 166 | } |
| 167 | return strings.TrimSpace(string(data)) |
| 168 | } |
| 169 | |
| 170 | func decodeWireError(method string, data []byte) error { |
| 171 | var we wireError |
| 172 | if err := json.Unmarshal(data, &we); err != nil || we.Error == "" { |
| 173 | return fmt.Errorf("browser broker: %s: status 409: %s", method, strings.TrimSpace(string(data))) |
| 174 | } |
| 175 | sentinel, ok := wireErrorCodes[we.Error] |
| 176 | if !ok { |
| 177 | return fmt.Errorf("browser broker: %s: %s: %s", method, we.Error, we.Message) |
| 178 | } |
| 179 | detail := strings.TrimPrefix(strings.TrimPrefix(we.Message, sentinel.Error()), ": ") |
| 180 | if detail == "" { |
| 181 | return sentinel |
| 182 | } |
| 183 | return fmt.Errorf("%w: %s", sentinel, detail) |
| 184 | } |
| 185 | |
| 186 | func (e *httpExecutor) Tabs(ctx context.Context) ([]Tab, error) { |
| 187 | var out wireTabs |
| 188 | if err := e.call(ctx, "tabs", struct{}{}, &out); err != nil { |
| 189 | return nil, err |
| 190 | } |
| 191 | tabs := make([]Tab, 0, len(out.Tabs)) |
| 192 | for _, t := range out.Tabs { |
| 193 | tabs = append(tabs, t.tab()) |
| 194 | } |
| 195 | return tabs, nil |
| 196 | } |
| 197 | |
| 198 | func (e *httpExecutor) Open(ctx context.Context, req OpenRequest) (Tab, error) { |
| 199 | var out wireTab |
| 200 | if err := e.write(ctx, "open", wireOpenRequest(req), &out); err != nil { |
| 201 | return Tab{}, err |
| 202 | } |
| 203 | return out.tab(), nil |
| 204 | } |
| 205 | |
| 206 | func (e *httpExecutor) Navigate(ctx context.Context, req NavigateRequest) (Tab, error) { |
| 207 | var out wireTab |
| 208 | if err := e.write(ctx, "navigate", wireNavigateRequest(req), &out); err != nil { |
| 209 | return Tab{}, err |
| 210 | } |
| 211 | return out.tab(), nil |
| 212 | } |
| 213 | |
| 214 | func (e *httpExecutor) Snapshot(ctx context.Context, req SnapshotRequest) (Snapshot, error) { |
| 215 | var out wireSnapshot |
| 216 | if err := e.call(ctx, "snapshot", wireSnapshotRequest(req), &out); err != nil { |
| 217 | return Snapshot{}, err |
| 218 | } |
| 219 | return Snapshot(out), nil |
| 220 | } |
| 221 | |
| 222 | func (e *httpExecutor) Screenshot(ctx context.Context, req ScreenshotRequest) (Screenshot, error) { |
| 223 | var out wireScreenshot |
| 224 | if err := e.call(ctx, "screenshot", wireScreenshotRequest(req), &out); err != nil { |
| 225 | return Screenshot{}, err |
| 226 | } |
| 227 | return Screenshot(out), nil |
| 228 | } |
| 229 | |
| 230 | // Act sends one reserved write. A reply that never arrived leaves the |
| 231 | // action's fate unknown, which is exactly ErrUnknownOutcome. |
| 232 | func (e *httpExecutor) Act(ctx context.Context, req ActRequest) (ActResult, error) { |
| 233 | var out wireActResult |
| 234 | if err := e.write(ctx, "act", toWireAct(req), &out); err != nil { |
| 235 | if errors.Is(err, ErrUnknownOutcome) { |
| 236 | return ActResult{Outcome: OutcomeUnknown}, err |
| 237 | } |
| 238 | return ActResult{}, err |
| 239 | } |
| 240 | res := ActResult(out) |
| 241 | if res.Outcome == "" { |
| 242 | res.Outcome = OutcomeNotExecuted |
| 243 | if res.Executed { |
| 244 | res.Outcome = OutcomeExecuted |
| 245 | } |
| 246 | } |
| 247 | return res, nil |
| 248 | } |
| 249 | |
| 250 | func (e *httpExecutor) Downloads(ctx context.Context, req DownloadsRequest) ([]Download, error) { |
| 251 | var out wireDownloads |
| 252 | in := wireDownloadsRequest{TabID: req.TabID, WaitForMs: req.WaitFor.Milliseconds()} |
| 253 | if err := e.call(ctx, "downloads", in, &out); err != nil { |
| 254 | return nil, err |
| 255 | } |
| 256 | downloads := make([]Download, 0, len(out.Downloads)) |
| 257 | for _, d := range out.Downloads { |
| 258 | downloads = append(downloads, Download(d)) |
| 259 | } |
| 260 | return downloads, nil |
| 261 | } |
| 262 | |
| 263 | func (e *httpExecutor) Close(ctx context.Context, req CloseRequest) error { |
| 264 | return e.write(ctx, "close", wireCloseRequest(req), nil) |
| 265 | } |
| 266 | |
| 267 | // Once a write is handed to HTTP, only explicit refusal codes prove it did |
| 268 | // not run. Truncated/invalid replies and HTTP failures also leave it unknown. |
| 269 | func (e *httpExecutor) write(ctx context.Context, method string, in, out any) error { |
| 270 | err := e.call(ctx, method, in, out) |
| 271 | if err == nil || errors.Is(err, ErrStaleReference) || errors.Is(err, ErrTakenOver) || errors.Is(err, ErrNoGrant) || errors.Is(err, ErrUnknownOutcome) { |
| 272 | return err |
| 273 | } |
| 274 | return fmt.Errorf("%w: %s", ErrUnknownOutcome, err.Error()) |
| 275 | } |
| 276 |