keep track of login attempts, both successful and failures

and show them in the account and admin interfaces. this should help with
debugging, to find misconfigured clients, and potentially find attackers trying
to login.

we include details like login name, account name, protocol, authentication
mechanism, ip addresses, tls connection properties, user-agent. and of course
the result.

we group entries by their details. repeat connections don't cause new records
in the database, they just increase the count on the existing record.

we keep data for at most 30 days. and we keep at most 10k entries per account.
to prevent unbounded growth. for successful login attempts, we store them all
for 30d. if a bad user causes so many entries this becomes a problem, it will
be time to talk to the user...

there is no pagination/searching yet in the admin/account interfaces. so the
list may be long. we only show the 10 most recent login attempts by default.
the rest is only shown on a separate page.

there is no way yet to disable this. may come later, either as global setting
or per account.

webauth/webauth.go

@@ -77,6 +77,23 @@ type SessionAuth interface {
 	remove(ctx context.Context, log mlog.Log, accountName string, sessionToken store.SessionToken) error
 }
 
+// loginAttempt initializes a loginAttempt, for adding to the store after filling in the results and other details.
+func loginAttempt(r *http.Request, protocol, authMech string) store.LoginAttempt {
+	remoteIP, _, _ := net.SplitHostPort(r.RemoteAddr)
+	if remoteIP == "" {
+		remoteIP = r.RemoteAddr
+	}
+
+	return store.LoginAttempt{
+		RemoteIP:  remoteIP,
+		TLS:       store.LoginAttemptTLS(r.TLS),
+		Protocol:  protocol,
+		AuthMech:  authMech,
+		UserAgent: r.UserAgent(),
+		Result:    store.AuthError, // Replaced by caller.
+	}
+}
+
 // Check authentication for a request based on session token in cookie and matching
 // csrf in case requireCSRF is set (from header, unless formCSRF is set). Also
 // performs rate limiting.
@@ -143,9 +160,9 @@ func Check(ctx context.Context, log mlog.Log, sessionAuth SessionAuth, kind stri
 		return
 	}
 
-	authResult := "badcreds"
+	la := loginAttempt(r, kind, "websession")
 	defer func() {
-		metrics.AuthenticationInc(kind, "websession", authResult)
+		store.LoginAttemptAdd(context.Background(), log, la)
 	}()
 
 	// Cookie values are of the form: token SP accountname.
@@ -165,16 +182,19 @@ func Check(ctx context.Context, log mlog.Log, sessionAuth SessionAuth, kind stri
 		respondAuthError("user:badAuth", "malformed session account name")
 		return "", "", "", false
 	}
+	la.AccountName = accountName
 
 	loginAddress, err = sessionAuth.use(ctx, log, accountName, sessionToken, csrfToken)
 	if err != nil {
+		la.Result = store.AuthBadCredentials
 		time.Sleep(BadAuthDelay)
 		respondAuthError("user:badAuth", err.Error())
 		return "", "", "", false
 	}
+	la.LoginAddress = loginAddress
 
 	mox.LimiterFailedAuth.Reset(ip, start)
-	authResult = "ok"
+	la.Result = store.AuthSuccess
 
 	// Add to HTTP logging that this is an authenticated request.
 	if lw, ok := w.(interface{ AddAttr(a slog.Attr) }); ok {
@@ -247,26 +267,29 @@ func Login(ctx context.Context, log mlog.Log, sessionAuth SessionAuth, kind, coo
 	}
 
 	valid, disabled, accountName, err := sessionAuth.login(ctx, log, username, password)
-	var authResult string
+	la := loginAttempt(r, kind, "weblogin")
+	la.LoginAddress = username
+	la.AccountName = accountName
 	defer func() {
-		metrics.AuthenticationInc(kind, "weblogin", authResult)
+		store.LoginAttemptAdd(context.Background(), log, la)
 	}()
 	if disabled {
-		authResult = "logindisabled"
+		la.Result = store.AuthLoginDisabled
 		return "", &sherpa.Error{Code: "user:loginFailed", Message: err.Error()}
 	} else if err != nil {
-		authResult = "error"
+		la.Result = store.AuthError
 		return "", fmt.Errorf("evaluating login attempt: %v", err)
 	} else if !valid {
 		time.Sleep(BadAuthDelay)
-		authResult = "badcreds"
+		la.Result = store.AuthBadCredentials
 		return "", &sherpa.Error{Code: "user:loginFailed", Message: "invalid credentials"}
 	}
-	authResult = "ok"
+	la.Result = store.AuthSuccess
 	mox.LimiterFailedAuth.Reset(ip, start)
 
 	sessionToken, csrfToken, err := sessionAuth.add(ctx, log, accountName, username)
 	if err != nil {
+		la.Result = store.AuthError
 		log.Errorx("adding session after login", err)
 		return "", fmt.Errorf("adding session: %v", err)
 	}