| 1 | package callscore |
| 2 | |
| 3 | import ( |
| 4 | "amadan.net/oficina/calls/protocol" |
| 5 | "bytes" |
| 6 | "context" |
| 7 | "crypto/rand" |
| 8 | "crypto/sha256" |
| 9 | "encoding/base64" |
| 10 | "encoding/json" |
| 11 | "errors" |
| 12 | "io" |
| 13 | "net/http" |
| 14 | "net/url" |
| 15 | "strings" |
| 16 | "time" |
| 17 | ) |
| 18 | |
| 19 | // Authentication keeps the proof secret in the client while the user approves |
| 20 | // in their default browser. It works on desktop and mobile without a webview, |
| 21 | // custom URL scheme, or browser cookie extraction. |
| 22 | type Authentication struct { |
| 23 | origin, id, verifier, target string |
| 24 | client *http.Client |
| 25 | ctx context.Context |
| 26 | cancel context.CancelFunc |
| 27 | } |
| 28 | type AuthenticationResult struct { |
| 29 | Origin string `json:"origin"` |
| 30 | Room string `json:"room"` |
| 31 | Cookies []SessionCookie `json:"cookies"` |
| 32 | } |
| 33 | type SessionCookie struct { |
| 34 | Name string `json:"name"` |
| 35 | Value string `json:"value"` |
| 36 | } |
| 37 | |
| 38 | // meetingTarget splits an address a person pasted into the instance it |
| 39 | // is on and the path the app may ask for there. It is shared by the |
| 40 | // browser sign-in and by OpenLink, so an address means the same thing |
| 41 | // whether or not the app already holds a session for its instance. |
| 42 | // |
| 43 | // An address with no path at all is the instance itself, and the |
| 44 | // target is the meeting list: the person has no link because the |
| 45 | // meeting they are about to be in does not exist yet. Everything |
| 46 | // downstream of here treats an empty Room as that case. |
| 47 | func meetingTarget(address string) (origin, target string, err error) { |
| 48 | u, err := url.Parse(address) |
| 49 | if err != nil || u.User != nil || u.RawQuery != "" || u.Fragment != "" || u.RawPath != "" { |
| 50 | return "", "", errors.New("enter a full meeting or invitation link") |
| 51 | } |
| 52 | target = "/" |
| 53 | if trimmed := strings.Trim(u.Path, "/"); trimmed != "" { |
| 54 | parts := strings.Split(trimmed, "/") |
| 55 | if len(parts) == 3 && parts[0] == "m" && parts[2] == "join" { |
| 56 | parts = parts[:2] |
| 57 | } |
| 58 | if len(parts) != 2 || (parts[0] != "m" && parts[0] != "j") || len(parts[1]) == 0 || len(parts[1]) > 128 || strings.IndexFunc(parts[1], func(r rune) bool { |
| 59 | return !(r >= 'a' && r <= 'z' || r >= 'A' && r <= 'Z' || r >= '0' && r <= '9' || r == '_' || r == '-') |
| 60 | }) >= 0 { |
| 61 | return "", "", errors.New("enter a full meeting or invitation link") |
| 62 | } |
| 63 | target = "/" + strings.Join(parts, "/") |
| 64 | } |
| 65 | return u.Scheme + "://" + u.Host, target, nil |
| 66 | } |
| 67 | |
| 68 | // invitationRoom reads the answer to following an invitation with a |
| 69 | // session: a 303 to the meeting's holding page, relative, on this |
| 70 | // instance. Anything else — a sign-in page, the guest name form, a 404 |
| 71 | // for a replaced link — is not a meeting this session can enter. |
| 72 | func invitationRoom(response *http.Response) (string, error) { |
| 73 | location, err := url.Parse(response.Header.Get("Location")) |
| 74 | if err != nil || response.StatusCode != 303 || location.IsAbs() || location.Host != "" || !strings.HasPrefix(location.Path, "/m/") || !strings.HasSuffix(location.Path, "/join") { |
| 75 | return "", errors.New("invitation is unavailable") |
| 76 | } |
| 77 | return strings.TrimSuffix(strings.TrimPrefix(location.Path, "/m/"), "/join"), nil |
| 78 | } |
| 79 | |
| 80 | func BeginAuthentication(ctx context.Context, address string) (*Authentication, error) { |
| 81 | return beginAuthentication(ctx, address, "") |
| 82 | } |
| 83 | |
| 84 | // ErrOfferExpired is BeginOfferAuthentication's refusal of an offer that |
| 85 | // has gone: five minutes passed, or the offer was already taken up. |
| 86 | var ErrOfferExpired = errors.New("this Join in the app link has expired or was already used; choose Join in the app on the meeting page again") |
| 87 | |
| 88 | // BeginOfferAuthentication is BeginAuthentication for the web's "Join in |
| 89 | // the app" (2026-10-02): the link that opened the app carries an offer |
| 90 | // the person's signed-in browser made, and the request names it, so the |
| 91 | // browser page that made it — not whichever browser BrowserURL would |
| 92 | // open — asks the person to confirm. Everything else is the same: the |
| 93 | // verifier stays here, the session is released only to it, once. |
| 94 | func BeginOfferAuthentication(ctx context.Context, address, offer string) (*Authentication, error) { |
| 95 | if !authToken(offer) { |
| 96 | return nil, errors.New("this Join in the app link is not valid") |
| 97 | } |
| 98 | return beginAuthentication(ctx, address, offer) |
| 99 | } |
| 100 | |
| 101 | func beginAuthentication(ctx context.Context, address, offer string) (*Authentication, error) { |
| 102 | origin, target, err := meetingTarget(address) |
| 103 | if err != nil { |
| 104 | return nil, err |
| 105 | } |
| 106 | transport, err := newTransport(origin, "auth", &http.Client{}) |
| 107 | if err != nil { |
| 108 | return nil, err |
| 109 | } |
| 110 | ctx, cancel := context.WithTimeout(ctx, 5*time.Minute) |
| 111 | raw := make([]byte, 32) |
| 112 | if _, err = rand.Read(raw); err != nil { |
| 113 | cancel() |
| 114 | return nil, errors.New("cannot start sign-in") |
| 115 | } |
| 116 | a := &Authentication{origin: origin, verifier: base64.RawURLEncoding.EncodeToString(raw), target: target, client: transport.http, ctx: ctx, cancel: cancel} |
| 117 | hash := sha256.Sum256([]byte(a.verifier)) |
| 118 | input := map[string]string{"challenge": base64.RawURLEncoding.EncodeToString(hash[:]), "target": a.target} |
| 119 | if offer != "" { |
| 120 | input["offer"] = offer |
| 121 | } |
| 122 | res, err := a.post("request", input) |
| 123 | if err != nil { |
| 124 | cancel() |
| 125 | return nil, err |
| 126 | } |
| 127 | defer res.Body.Close() |
| 128 | if offer != "" && res.StatusCode == http.StatusGone { |
| 129 | cancel() |
| 130 | return nil, ErrOfferExpired |
| 131 | } |
| 132 | if res.StatusCode != 200 { |
| 133 | cancel() |
| 134 | return nil, errors.New("this Calls server does not support native sign-in yet, or is temporarily unavailable") |
| 135 | } |
| 136 | var out struct { |
| 137 | ID string `json:"id"` |
| 138 | Offer bool `json:"offer"` |
| 139 | } |
| 140 | if json.NewDecoder(io.LimitReader(res.Body, 2048)).Decode(&out) != nil || !authToken(out.ID) { |
| 141 | cancel() |
| 142 | return nil, errors.New("invalid sign-in response") |
| 143 | } |
| 144 | // A server that ignored the offer made an ordinary request, which |
| 145 | // only BrowserURL's browser can approve. Said rather than waited on. |
| 146 | if offer != "" && !out.Offer { |
| 147 | cancel() |
| 148 | return nil, errors.New("this Calls server cannot hand a web sign-in to the app; choose Sign in instead") |
| 149 | } |
| 150 | a.id = out.ID |
| 151 | return a, nil |
| 152 | } |
| 153 | func authToken(s string) bool { |
| 154 | b, e := base64.RawURLEncoding.DecodeString(s) |
| 155 | return e == nil && len(b) == 32 && base64.RawURLEncoding.EncodeToString(b) == s |
| 156 | } |
| 157 | func (a *Authentication) BrowserURL() string { return a.origin + "/native/start?id=" + a.id } |
| 158 | func (a *Authentication) Cancel() { a.cancel() } |
| 159 | func (a *Authentication) post(path string, input any) (*http.Response, error) { |
| 160 | b, _ := json.Marshal(input) |
| 161 | ctx, cancel := context.WithTimeout(a.ctx, 15*time.Second) |
| 162 | // Keep the request deadline alive through the response body read. |
| 163 | req, _ := http.NewRequestWithContext(ctx, "POST", a.origin+"/native/"+path, bytes.NewReader(b)) |
| 164 | req.Header.Set("Content-Type", "application/json") |
| 165 | res, e := a.client.Do(req) |
| 166 | if e != nil { |
| 167 | cancel() |
| 168 | return nil, errors.New("cannot reach Calls; try signing in again") |
| 169 | } |
| 170 | res.Body = &authBody{ReadCloser: res.Body, cancel: cancel} |
| 171 | return res, nil |
| 172 | } |
| 173 | |
| 174 | type authBody struct { |
| 175 | io.ReadCloser |
| 176 | cancel context.CancelFunc |
| 177 | } |
| 178 | |
| 179 | func (b *authBody) Close() error { defer b.cancel(); return b.ReadCloser.Close() } |
| 180 | func (a *Authentication) Wait() (*AuthenticationResult, error) { |
| 181 | defer a.cancel() |
| 182 | timer := time.NewTicker(2 * time.Second) |
| 183 | defer timer.Stop() |
| 184 | for { |
| 185 | select { |
| 186 | case <-a.ctx.Done(): |
| 187 | return nil, errors.New("sign-in cancelled or expired; try again") |
| 188 | case <-timer.C: |
| 189 | } |
| 190 | res, e := a.post("exchange", map[string]string{"id": a.id, "verifier": a.verifier}) |
| 191 | if e != nil { |
| 192 | return nil, e |
| 193 | } |
| 194 | if res.StatusCode == 202 { |
| 195 | res.Body.Close() |
| 196 | continue |
| 197 | } |
| 198 | var out struct { |
| 199 | Name string `json:"name"` |
| 200 | Value string `json:"value"` |
| 201 | Target string `json:"target"` |
| 202 | } |
| 203 | err := json.NewDecoder(io.LimitReader(res.Body, 2048)).Decode(&out) |
| 204 | res.Body.Close() |
| 205 | expected := "__Host-rastrillo_session" |
| 206 | if strings.HasPrefix(a.origin, "http:") { |
| 207 | expected = "rastrillo_session" |
| 208 | } |
| 209 | if res.StatusCode != 200 || err != nil || out.Name != expected || !authToken(out.Value) || out.Target != a.target { |
| 210 | return nil, errors.New("sign-in expired or was refused; try again") |
| 211 | } |
| 212 | // The meeting list signs in without a meeting: there is no room |
| 213 | // to name, no invitation to follow and nothing to validate. The |
| 214 | // host reads the empty Room as "signed in, nowhere yet". |
| 215 | if a.target == "/" { |
| 216 | return &AuthenticationResult{Origin: a.origin, Cookies: []SessionCookie{{Name: out.Name, Value: out.Value}}}, nil |
| 217 | } |
| 218 | room := strings.TrimPrefix(a.target, "/m/") |
| 219 | if strings.HasPrefix(a.target, "/j/") { |
| 220 | req, _ := http.NewRequestWithContext(a.ctx, "GET", a.origin+a.target, nil) |
| 221 | req.AddCookie(&http.Cookie{Name: out.Name, Value: out.Value}) |
| 222 | response, err := a.client.Do(req) |
| 223 | if err != nil { |
| 224 | return nil, errors.New("cannot open invitation") |
| 225 | } |
| 226 | response.Body.Close() |
| 227 | if room, err = invitationRoom(response); err != nil { |
| 228 | return nil, err |
| 229 | } |
| 230 | } |
| 231 | if _, e := newTransport(a.origin, room, a.client); e != nil { |
| 232 | return nil, e |
| 233 | } |
| 234 | return &AuthenticationResult{Origin: a.origin, Room: room, Cookies: []SessionCookie{{Name: out.Name, Value: out.Value}}}, nil |
| 235 | } |
| 236 | } |
| 237 | |
| 238 | func (a *Authentication) ConfirmationCode() string { return protocol.AuthenticationCode(a.id) } |
| 239 | |
amadan