Initial Commit

registration.go

@@ -0,0 +1,135 @@
+package main
+
+import (
+	"bytes"
+	"crypto/hmac"
+	"crypto/sha1"
+	"encoding/hex"
+	"encoding/json"
+	"errors"
+	"log/slog"
+	"net/http"
+	"net/url"
+	"os"
+)
+
+// regEndpoint is the endpoint for shared secret registration
+const regEndpoint = "/_synapse/admin/v1/register"
+
+// RegistrationReq represents the JSON body of a registration request
+type RegistrationReq struct {
+	Nonce       string `json:"nonce"`
+	Username    string `json:"username"`
+	DisplayName string `json:"displayname"`
+	Password    string `json:"password"`
+	Admin       bool   `json:"admin"`
+	MAC         string `json:"mac"`
+}
+
+// registerUser registers the given user with the matrix server
+func registerUser(username, displayName, password string, u url.URL) error {
+	u.Path = regEndpoint
+	req, err := generateRegRequest(username, displayName, password, u)
+	if err != nil {
+		return err
+	}
+
+	data, err := json.Marshal(req)
+	if err != nil {
+		return err
+	}
+
+	log.Info("Issuing registration request",
+		slog.String("username", req.Username),
+		slog.String("nonce", req.Nonce),
+		slog.String("mac", req.MAC),
+	)
+	
+	res, err := http.Post(u.String(), "application/json", bytes.NewReader(data))
+	if err != nil {
+		return err
+	}
+	defer res.Body.Close()
+
+	if res.StatusCode != 200 {
+		var errRes struct {
+			Message string `json:"message"`
+			ErrCode string `json:"errcode"`
+			Error   string `json:"error"`
+		}
+
+		err = json.NewDecoder(res.Body).Decode(&errRes)
+		if err != nil || (errRes.Message == "" && errRes.Error == "") {
+			return errors.New("http: " + res.Status)
+		} else if errRes.Error != "" {
+			return errors.New(u.Host + ": " + errRes.ErrCode + ": " + errRes.Error)
+		} else {
+			return errors.New(u.Host + ": " + errRes.Message)
+		}
+	}
+
+	return nil
+}
+
+// generateRegRequest generates the JSON struct that will serve as the body of a use registration request
+func generateRegRequest(username, displayName, password string, u url.URL) (*RegistrationReq, error) {
+	secret := os.Getenv("SHARED_SECRET")
+
+	nonce, err := getNonce(u)
+	if err != nil {
+		return nil, err
+	}
+
+	mac, err := calculateMAC(secret, username, password, nonce)
+	if err != nil {
+		return nil, err
+	}
+
+	return &RegistrationReq{
+		nonce,
+		username,
+		displayName,
+		password,
+		false,
+		mac,
+	}, nil
+}
+
+// getNonce requests and returns a nonce from the matrix server
+func getNonce(u url.URL) (string, error) {
+	u.Path = regEndpoint
+	res, err := http.Get(u.String())
+	if err != nil {
+		return "", err
+	}
+	defer res.Body.Close()
+
+	if res.StatusCode != 200 {
+		return "", errors.New("http: " + res.Status)
+	}
+
+	var resp struct {
+		Nonce string `json:"nonce"`
+	}
+	err = json.NewDecoder(res.Body).Decode(&resp)
+	if err != nil {
+		return "", err
+	}
+
+	return resp.Nonce, nil
+}
+
+// calculateMAC calculates a returns an HMAC-SHA1 for a new non-admin user
+func calculateMAC(secret, username, password, nonce string) (string, error) {
+	h := hmac.New(sha1.New, []byte(secret))
+	b := &bytes.Buffer{}
+	b.WriteString(nonce)
+	b.WriteByte(0)
+	b.WriteString(username)
+	b.WriteByte(0)
+	b.WriteString(password)
+	b.WriteByte(0)
+	b.WriteString("notadmin")
+	b.WriteTo(h)
+	return hex.EncodeToString(h.Sum(nil)), nil
+}