add per-account quota for total message size disk usage

so a single user cannot fill up the disk.
by default, there is (still) no limit. a default can be set in the config file
for all accounts, and a per-account max size can be set that would override any
global setting.

this does not take into account disk usage of the index database. and also not
of any file system overhead.

webadmin/admin.html

@@ -491,9 +491,50 @@ const account = async (name) => {
 	const config = await api.Account(name)
 
 	let form, fieldset, email
-	let formSendlimits, fieldsetSendlimits, maxOutgoingMessagesPerDay, maxFirstTimeRecipientsPerDay
+	let formLimits, fieldsetLimits, maxOutgoingMessagesPerDay, maxFirstTimeRecipientsPerDay, quotaMessageSize
 	let formPassword, fieldsetPassword, password, passwordHint
 
+	const xparseSize = (s) => {
+		const origs = s
+		s = s.toLowerCase()
+		let mult = 1
+		if (s.endsWith('k')) {
+			mult = 1024
+		} else if (s.endsWith('m')) {
+			mult = 1024*1024
+		} else if (s.endsWith('g')) {
+			mult = 1024*1024*1024
+		} else if (s.endsWith('t')) {
+			mult = 1024*1024*1024*1024
+		}
+		if (mult !== 1) {
+			s = s.substring(0, s.length-1)
+		}
+		let v = parseInt(s)
+		console.log('x', s, v, mult, formatQuotaSize(v*mult))
+		if (isNaN(v) || origs !== formatQuotaSize(v*mult)) {
+			throw new Error('invalid number')
+		}
+		return v*mult
+	}
+
+	const formatQuotaSize = (v) => {
+		if (v === 0) {
+			return '0'
+		}
+		const m = 1024*1024
+		const g = m*1024
+		const t = g*1024
+		if (Math.floor(v/t)*t === v) {
+			return ''+(v/t)+'t'
+		} else if (Math.floor(v/g)*g === v) {
+			return ''+(v/g)+'g'
+		} else if (Math.floor(v/m)*m === v) {
+			return ''+(v/m)+'m'
+		}
+		return ''+v
+	}
+
 	const page = document.getElementById('page')
 	dom._kids(page,
 		crumbs(
@@ -595,38 +636,42 @@ const account = async (name) => {
 			),
 		),
 		dom.br(),
-		dom.h2('Send limits'),
-		formSendlimits=dom.form(
-			fieldsetSendlimits=dom.fieldset(
+		dom.h2('Limits'),
+		formLimits=dom.form(
+			fieldsetLimits=dom.fieldset(
 				dom.label(
-					style({display: 'inline-block'}),
+					style({display: 'block', marginBottom: '.5ex'}),
 					dom.span('Maximum outgoing messages per day', attr({title: 'Maximum number of outgoing messages for this account in a 24 hour window. This limits the damage to recipients and the reputation of this mail server in case of account compromise. Default 1000. MaxOutgoingMessagesPerDay in configuration file.'})),
 					dom.br(),
 					maxOutgoingMessagesPerDay=dom.input(attr({type: 'number', required: '', value: config.MaxOutgoingMessagesPerDay || 1000})),
 				),
-				' ',
 				dom.label(
-					style({display: 'inline-block'}),
+					style({display: 'block', marginBottom: '.5ex'}),
 					dom.span('Maximum first-time recipients per day', attr({title: 'Maximum number of first-time recipients in outgoing messages for this account in a 24 hour window. This limits the damage to recipients and the reputation of this mail server in case of account compromise. Default 200. MaxFirstTimeRecipientsPerDay in configuration file.'})),
 					dom.br(),
 					maxFirstTimeRecipientsPerDay=dom.input(attr({type: 'number', required: '', value: config.MaxFirstTimeRecipientsPerDay || 200})),
 				),
-				' ',
+				dom.label(
+					style({display: 'block', marginBottom: '.5ex'}),
+					dom.span('Disk usage quota: Maximum total message size ', attr({title: 'Default maximum total message size for the account, overriding any globally configured maximum size if non-zero. A negative value can be used to have no limit in case there is a limit by default. Attempting to add new messages beyond the maximum size will result in an error. Useful to prevent a single account from filling storage.'})),
+					dom.br(),
+					quotaMessageSize=dom.input(attr({value: formatQuotaSize(config.QuotaMessageSize)})),
+				),
 				dom.button('Save'),
 			),
 			async function submit(e) {
 				e.stopPropagation()
 				e.preventDefault()
-				fieldsetSendlimits.disabled = true
+				fieldsetLimits.disabled = true
 				try {
-					await api.SetAccountLimits(name, parseInt(maxOutgoingMessagesPerDay.value) || 0, parseInt(maxFirstTimeRecipientsPerDay.value) || 0)
-					window.alert('Send limits saved.')
+					await api.SetAccountLimits(name, parseInt(maxOutgoingMessagesPerDay.value) || 0, parseInt(maxFirstTimeRecipientsPerDay.value) || 0, xparseSize(quotaMessageSize.value))
+					window.alert('Limits saved.')
 				} catch (err) {
 					console.log({err})
 					window.alert('Error: ' + err.message)
 					return
 				} finally {
-					fieldsetSendlimits.disabled = false
+					fieldsetLimits.disabled = false
 				}
 			},
 		),