| 1 | package client |
| 2 | |
| 3 | import ( |
| 4 | "bytes" |
| 5 | "encoding/json" |
| 6 | "fmt" |
| 7 | "net/http" |
| 8 | "net/url" |
| 9 | "strings" |
| 10 | "time" |
| 11 | |
| 12 | "lchat/internal/e2ee" |
| 13 | ) |
| 14 | |
| 15 | // JoinResult says what kind of link Join claimed, beyond the identity itself. |
| 16 | type JoinResult struct { |
| 17 | // AddDevice: the link carried an existing member's keypair — the session is |
| 18 | // that member's identity on a new device, not a new person. |
| 19 | AddDevice bool |
| 20 | // ThreadID is the pending DM a user invite drops the joiner into ("" for |
| 21 | // other link kinds) — a client can open it first. |
| 22 | ThreadID string |
| 23 | } |
| 24 | |
| 25 | // Join is web/static/join.js run headlessly: turn any invite link into a local |
| 26 | // identity. It handles all three link shapes — a fresh-person invite (generate |
| 27 | // a keypair, register it), a member-minted user invite (additionally re-wrap |
| 28 | // the pending DM's key to the new keypair), and an add-device link (adopt the |
| 29 | // keypair the link carries; the session then IS that member). The secret T |
| 30 | // never reaches the server: the invite id and claim secret derive from it, and |
| 31 | // whatever the link's wrapped blob holds decrypts locally. |
| 32 | func Join(base, fragment, name string) (*Session, JoinResult, error) { |
| 33 | base = strings.TrimRight(base, "/") |
| 34 | hc := &http.Client{Timeout: 30 * time.Second} |
| 35 | |
| 36 | inv, err := e2ee.DeriveInvite(fragment) |
| 37 | if err != nil { |
| 38 | return nil, JoinResult{}, fmt.Errorf("client: bad invite secret: %w", err) |
| 39 | } |
| 40 | |
| 41 | var info struct { |
| 42 | OK bool `json:"ok"` |
| 43 | Wrapped string `json:"wrapped"` |
| 44 | } |
| 45 | if err := getJSON(hc, base+"/api/key-invite/"+url.PathEscape(inv.ID), &info); err != nil { |
| 46 | return nil, JoinResult{}, err |
| 47 | } |
| 48 | if !info.OK { |
| 49 | return nil, JoinResult{}, fmt.Errorf("client: this invite was already used or has expired — ask for a fresh one") |
| 50 | } |
| 51 | |
| 52 | // What the link carries decides who we become (join.js): a keypair means |
| 53 | // add-device; a thread key means a user invite with a pending DM; nothing |
| 54 | // means a plain fresh-person invite. |
| 55 | var payload struct { |
| 56 | Priv string `json:"priv"` |
| 57 | Pub string `json:"pub"` |
| 58 | ThreadKey string `json:"threadKey"` |
| 59 | } |
| 60 | if info.Wrapped != "" { |
| 61 | if err := e2ee.DecryptJSON(inv.WrapKey, info.Wrapped, &payload); err != nil { |
| 62 | return nil, JoinResult{}, fmt.Errorf("client: couldn't unlock this link (wrong or corrupt secret)") |
| 63 | } |
| 64 | } |
| 65 | |
| 66 | pub, priv := payload.Pub, payload.Priv |
| 67 | wrappedSelf := "" |
| 68 | if priv == "" { |
| 69 | kp, err := e2ee.GenerateUserKeypair() |
| 70 | if err != nil { |
| 71 | return nil, JoinResult{}, err |
| 72 | } |
| 73 | pub, priv = kp.PublicKey, kp.PrivateKey |
| 74 | if payload.ThreadKey != "" { |
| 75 | // User invite: re-wrap the pending DM's key to our new keypair so the |
| 76 | // chat with the person who invited us opens readable. |
| 77 | if wrappedSelf, err = e2ee.WrapThreadKey(payload.ThreadKey, pub); err != nil { |
| 78 | return nil, JoinResult{}, err |
| 79 | } |
| 80 | } |
| 81 | } |
| 82 | |
| 83 | var claim struct { |
| 84 | OK bool `json:"ok"` |
| 85 | Token string `json:"token"` |
| 86 | ThreadID string `json:"thread_id"` |
| 87 | } |
| 88 | err = postJSON(hc, base+"/api/key-invite/"+url.PathEscape(inv.ID)+"/claim", |
| 89 | map[string]string{"claim_secret": inv.ClaimSecret, "wrapped": wrappedSelf}, &claim) |
| 90 | if err != nil { |
| 91 | return nil, JoinResult{}, err |
| 92 | } |
| 93 | if !claim.OK || claim.Token == "" { |
| 94 | return nil, JoinResult{}, fmt.Errorf("client: couldn't claim the invite (it may have just been used)") |
| 95 | } |
| 96 | |
| 97 | // Register (or, on add-device, harmlessly re-register) the public key. |
| 98 | err = postJSON(hc, base+"/api/pubkey", map[string]string{"token": claim.Token, "public_key": pub}, nil) |
| 99 | if err != nil { |
| 100 | return nil, JoinResult{}, err |
| 101 | } |
| 102 | |
| 103 | sess := &Session{Base: base, Token: claim.Token, Name: name, UserPub: pub, UserPriv: priv} |
| 104 | return sess, JoinResult{AddDevice: payload.Priv != "", ThreadID: claim.ThreadID}, nil |
| 105 | } |
| 106 | |
| 107 | func getJSON(hc *http.Client, url string, out any) error { |
| 108 | resp, err := hc.Get(url) |
| 109 | if err != nil { |
| 110 | return err |
| 111 | } |
| 112 | defer resp.Body.Close() |
| 113 | return json.NewDecoder(resp.Body).Decode(out) |
| 114 | } |
| 115 | |
| 116 | func postJSON(hc *http.Client, url string, body, out any) error { |
| 117 | raw, err := json.Marshal(body) |
| 118 | if err != nil { |
| 119 | return err |
| 120 | } |
| 121 | resp, err := hc.Post(url, "application/json", bytes.NewReader(raw)) |
| 122 | if err != nil { |
| 123 | return err |
| 124 | } |
| 125 | defer resp.Body.Close() |
| 126 | if out == nil { |
| 127 | if resp.StatusCode != http.StatusOK { |
| 128 | return fmt.Errorf("client: %s: HTTP %d", url, resp.StatusCode) |
| 129 | } |
| 130 | return nil |
| 131 | } |
| 132 | return json.NewDecoder(resp.Body).Decode(out) |
| 133 | } |
| 134 | |
amadan