move config-changing code from package mox-/ to admin/

needed for upcoming changes, where (now) package admin needs to import package
store. before, because package store imports mox- (for accessing the active
config), that would lead to a cyclic import. package mox- keeps its active
config, package admin has the higher-level config-changing functions.

admin/clientconfig.go

@@ -0,0 +1,168 @@
+package admin
+
+import (
+	"fmt"
+	"sort"
+
+	"golang.org/x/exp/maps"
+
+	"github.com/mjl-/mox/config"
+	"github.com/mjl-/mox/dns"
+	"github.com/mjl-/mox/mox-"
+)
+
+type TLSMode uint8
+
+const (
+	TLSModeImmediate TLSMode = 0
+	TLSModeSTARTTLS  TLSMode = 1
+	TLSModeNone      TLSMode = 2
+)
+
+type ProtocolConfig struct {
+	Host    dns.Domain
+	Port    int
+	TLSMode TLSMode
+}
+
+type ClientConfig struct {
+	IMAP       ProtocolConfig
+	Submission ProtocolConfig
+}
+
+// ClientConfigDomain returns a single IMAP and Submission client configuration for
+// a domain.
+func ClientConfigDomain(d dns.Domain) (rconfig ClientConfig, rerr error) {
+	var haveIMAP, haveSubmission bool
+
+	domConf, ok := mox.Conf.Domain(d)
+	if !ok {
+		return ClientConfig{}, fmt.Errorf("%w: unknown domain", ErrRequest)
+	}
+
+	gather := func(l config.Listener) (done bool) {
+		host := mox.Conf.Static.HostnameDomain
+		if l.Hostname != "" {
+			host = l.HostnameDomain
+		}
+		if domConf.ClientSettingsDomain != "" {
+			host = domConf.ClientSettingsDNSDomain
+		}
+		if !haveIMAP && l.IMAPS.Enabled {
+			rconfig.IMAP.Host = host
+			rconfig.IMAP.Port = config.Port(l.IMAPS.Port, 993)
+			rconfig.IMAP.TLSMode = TLSModeImmediate
+			haveIMAP = true
+		}
+		if !haveIMAP && l.IMAP.Enabled {
+			rconfig.IMAP.Host = host
+			rconfig.IMAP.Port = config.Port(l.IMAP.Port, 143)
+			rconfig.IMAP.TLSMode = TLSModeSTARTTLS
+			if l.TLS == nil {
+				rconfig.IMAP.TLSMode = TLSModeNone
+			}
+			haveIMAP = true
+		}
+		if !haveSubmission && l.Submissions.Enabled {
+			rconfig.Submission.Host = host
+			rconfig.Submission.Port = config.Port(l.Submissions.Port, 465)
+			rconfig.Submission.TLSMode = TLSModeImmediate
+			haveSubmission = true
+		}
+		if !haveSubmission && l.Submission.Enabled {
+			rconfig.Submission.Host = host
+			rconfig.Submission.Port = config.Port(l.Submission.Port, 587)
+			rconfig.Submission.TLSMode = TLSModeSTARTTLS
+			if l.TLS == nil {
+				rconfig.Submission.TLSMode = TLSModeNone
+			}
+			haveSubmission = true
+		}
+		return haveIMAP && haveSubmission
+	}
+
+	// Look at the public listener first. Most likely the intended configuration.
+	if public, ok := mox.Conf.Static.Listeners["public"]; ok {
+		if gather(public) {
+			return
+		}
+	}
+	// Go through the other listeners in consistent order.
+	names := maps.Keys(mox.Conf.Static.Listeners)
+	sort.Strings(names)
+	for _, name := range names {
+		if gather(mox.Conf.Static.Listeners[name]) {
+			return
+		}
+	}
+	return ClientConfig{}, fmt.Errorf("%w: no listeners found for imap and/or submission", ErrRequest)
+}
+
+// ClientConfigs holds the client configuration for IMAP/Submission for a
+// domain.
+type ClientConfigs struct {
+	Entries []ClientConfigsEntry
+}
+
+type ClientConfigsEntry struct {
+	Protocol string
+	Host     dns.Domain
+	Port     int
+	Listener string
+	Note     string
+}
+
+// ClientConfigsDomain returns the client configs for IMAP/Submission for a
+// domain.
+func ClientConfigsDomain(d dns.Domain) (ClientConfigs, error) {
+	domConf, ok := mox.Conf.Domain(d)
+	if !ok {
+		return ClientConfigs{}, fmt.Errorf("%w: unknown domain", ErrRequest)
+	}
+
+	c := ClientConfigs{}
+	c.Entries = []ClientConfigsEntry{}
+	var listeners []string
+
+	for name := range mox.Conf.Static.Listeners {
+		listeners = append(listeners, name)
+	}
+	sort.Slice(listeners, func(i, j int) bool {
+		return listeners[i] < listeners[j]
+	})
+
+	note := func(tls bool, requiretls bool) string {
+		if !tls {
+			return "plain text, no STARTTLS configured"
+		}
+		if requiretls {
+			return "STARTTLS required"
+		}
+		return "STARTTLS optional"
+	}
+
+	for _, name := range listeners {
+		l := mox.Conf.Static.Listeners[name]
+		host := mox.Conf.Static.HostnameDomain
+		if l.Hostname != "" {
+			host = l.HostnameDomain
+		}
+		if domConf.ClientSettingsDomain != "" {
+			host = domConf.ClientSettingsDNSDomain
+		}
+		if l.Submissions.Enabled {
+			c.Entries = append(c.Entries, ClientConfigsEntry{"Submission (SMTP)", host, config.Port(l.Submissions.Port, 465), name, "with TLS"})
+		}
+		if l.IMAPS.Enabled {
+			c.Entries = append(c.Entries, ClientConfigsEntry{"IMAP", host, config.Port(l.IMAPS.Port, 993), name, "with TLS"})
+		}
+		if l.Submission.Enabled {
+			c.Entries = append(c.Entries, ClientConfigsEntry{"Submission (SMTP)", host, config.Port(l.Submission.Port, 587), name, note(l.TLS != nil, !l.Submission.NoRequireSTARTTLS)})
+		}
+		if l.IMAP.Enabled {
+			c.Entries = append(c.Entries, ClientConfigsEntry{"IMAP", host, config.Port(l.IMAPS.Port, 143), name, note(l.TLS != nil, !l.IMAP.NoRequireSTARTTLS)})
+		}
+	}
+
+	return c, nil
+}