| 1 | package installsource |
| 2 | |
| 3 | import ( |
| 4 | "context" |
| 5 | "io" |
| 6 | "net/http" |
| 7 | "time" |
| 8 | ) |
| 9 | |
| 10 | // defaultFetchTimeout caps the lifetime of a single HTTP fetch. Without it a |
| 11 | // slow CDN can hold the agent tool call open until the user gives up. The |
| 12 | // value is generous (30s) so large SKILL.md bodies still load, but bounded so |
| 13 | // a hung server is not an open-ended wait. |
| 14 | const defaultFetchTimeout = 30 * time.Second |
| 15 | |
| 16 | // defaultFetchLimit is the maximum body size we will accept from a remote |
| 17 | // manifest. SKILL.md / .mcp.json files are normally a few KB; 2 MiB is a |
| 18 | // safety cap that prevents an untrusted mirror from streaming gigabytes into |
| 19 | // our parser. |
| 20 | const defaultFetchLimit = 2 << 20 |
| 21 | |
| 22 | // fetchText performs a bounded GET on sourceURL using the tool's HTTP client. |
| 23 | // It applies defaultFetchTimeout unless the caller's context already has a |
| 24 | // tighter deadline, and never reads more than defaultFetchLimit bytes. |
| 25 | func (t *installSourceTool) fetchText(ctx context.Context, sourceURL string) (string, error) { |
| 26 | if _, hasDeadline := ctx.Deadline(); !hasDeadline { |
| 27 | var cancel context.CancelFunc |
| 28 | ctx, cancel = context.WithTimeout(ctx, defaultFetchTimeout) |
| 29 | defer cancel() |
| 30 | } |
| 31 | req, err := http.NewRequestWithContext(ctx, http.MethodGet, sourceURL, nil) |
| 32 | if err != nil { |
| 33 | return "", newErr(ErrSourceUnreadable, "%s: %v", sourceURL, err) |
| 34 | } |
| 35 | if req.Header.Get("User-Agent") == "" { |
| 36 | req.Header.Set("User-Agent", "reasonix-install/1.0") |
| 37 | } |
| 38 | resp, err := t.httpClient.Do(req) |
| 39 | if err != nil { |
| 40 | return "", newErr(ErrSourceUnreadable, "%s: %v", sourceURL, err) |
| 41 | } |
| 42 | defer resp.Body.Close() |
| 43 | if resp.StatusCode == http.StatusUnauthorized || resp.StatusCode == http.StatusForbidden { |
| 44 | return "", newErr(ErrAuthRequired, "%s: HTTP %d", sourceURL, resp.StatusCode) |
| 45 | } |
| 46 | if resp.StatusCode < 200 || resp.StatusCode >= 300 { |
| 47 | return "", newErr(ErrSourceUnreadable, "%s: HTTP %d", sourceURL, resp.StatusCode) |
| 48 | } |
| 49 | limited := io.LimitReader(resp.Body, defaultFetchLimit) |
| 50 | body, err := io.ReadAll(limited) |
| 51 | if err != nil { |
| 52 | return "", newErr(ErrSourceUnreadable, "%s: read body: %v", sourceURL, err) |
| 53 | } |
| 54 | return string(body), nil |
| 55 | } |
| 56 |