add aliases/lists: when sending to an alias, the message gets delivered to all members

the members must currently all be addresses of local accounts.

a message sent to an alias is accepted if at least one of the members accepts
it. if no members accepts it (e.g. due to bad reputation of sender), the
message is rejected.

if a message is submitted to both an alias addresses and to recipients that are
members of the alias in an smtp transaction, the message will be delivered to
such members only once.  the same applies if the address in the message
from-header is the address of a member: that member won't receive the message
(they sent it). this prevents duplicate messages.

aliases have three configuration options:
- PostPublic: whether anyone can send through the alias, or only members.
  members-only lists can be useful inside organizations for internal
  communication. public lists can be useful for support addresses.
- ListMembers: whether members can see the addresses of other members. this can
  be seen in the account web interface. in the future, we could export this in
  other ways, so clients can expand the list.
- AllowMsgFrom: whether messages can be sent through the alias with the alias
  address used in the message from-header. the webmail knows it can use that
  address, and will use it as from-address when replying to a message sent to
  that address.

ideas for the future:
- allow external addresses as members. still with some restrictions, such as
  requiring a valid dkim-signature so delivery has a chance to succeed. will
  also need configuration of an admin that can receive any bounces.
- allow specifying specific members who can sent through the list (instead of
  all members).

for github issue #57 by hmfaysal.
also relevant for #99 by naturalethic.
thanks to damir & marin from sartura for discussing requirements/features.

webadmin/admin.go

@@ -1535,7 +1535,7 @@ func (Admin) DomainConfig(ctx context.Context, domain string) config.Domain {
 }
 
 // DomainLocalparts returns the encoded localparts and accounts configured in domain.
-func (Admin) DomainLocalparts(ctx context.Context, domain string) (localpartAccounts map[string]string) {
+func (Admin) DomainLocalparts(ctx context.Context, domain string) (localpartAccounts map[string]string, localpartAliases map[string]config.Alias) {
 	d, err := dns.ParseDomain(domain)
 	xcheckuserf(ctx, err, "parsing domain")
 	_, ok := mox.Conf.Domain(d)
@@ -2430,8 +2430,9 @@ func (Admin) AccountRoutesSave(ctx context.Context, accountName string, routes [
 
 // DomainRoutesSave saves routes for a domain.
 func (Admin) DomainRoutesSave(ctx context.Context, domainName string, routes []config.Route) {
-	err := mox.DomainSave(ctx, domainName, func(domain *config.Domain) {
+	err := mox.DomainSave(ctx, domainName, func(domain *config.Domain) error {
 		domain.Routes = routes
+		return nil
 	})
 	xcheckf(ctx, err, "saving domain routes")
 }
@@ -2446,16 +2447,18 @@ func (Admin) RoutesSave(ctx context.Context, routes []config.Route) {
 
 // DomainDescriptionSave saves the description for a domain.
 func (Admin) DomainDescriptionSave(ctx context.Context, domainName, descr string) {
-	err := mox.DomainSave(ctx, domainName, func(domain *config.Domain) {
+	err := mox.DomainSave(ctx, domainName, func(domain *config.Domain) error {
 		domain.Description = descr
+		return nil
 	})
 	xcheckf(ctx, err, "saving domain description")
 }
 
 // DomainClientSettingsDomainSave saves the client settings domain for a domain.
 func (Admin) DomainClientSettingsDomainSave(ctx context.Context, domainName, clientSettingsDomain string) {
-	err := mox.DomainSave(ctx, domainName, func(domain *config.Domain) {
+	err := mox.DomainSave(ctx, domainName, func(domain *config.Domain) error {
 		domain.ClientSettingsDomain = clientSettingsDomain
+		return nil
 	})
 	xcheckf(ctx, err, "saving client settings domain")
 }
@@ -2463,9 +2466,10 @@ func (Admin) DomainClientSettingsDomainSave(ctx context.Context, domainName, cli
 // DomainLocalpartConfigSave saves the localpart catchall and case-sensitive
 // settings for a domain.
 func (Admin) DomainLocalpartConfigSave(ctx context.Context, domainName, localpartCatchallSeparator string, localpartCaseSensitive bool) {
-	err := mox.DomainSave(ctx, domainName, func(domain *config.Domain) {
+	err := mox.DomainSave(ctx, domainName, func(domain *config.Domain) error {
 		domain.LocalpartCatchallSeparator = localpartCatchallSeparator
 		domain.LocalpartCaseSensitive = localpartCaseSensitive
+		return nil
 	})
 	xcheckf(ctx, err, "saving localpart settings for domain")
 }
@@ -2474,7 +2478,7 @@ func (Admin) DomainLocalpartConfigSave(ctx context.Context, domainName, localpar
 // configuration for a domain. If localpart is empty, processing reports is
 // disabled.
 func (Admin) DomainDMARCAddressSave(ctx context.Context, domainName, localpart, domain, account, mailbox string) {
-	err := mox.DomainSave(ctx, domainName, func(d *config.Domain) {
+	err := mox.DomainSave(ctx, domainName, func(d *config.Domain) error {
 		if localpart == "" {
 			d.DMARC = nil
 		} else {
@@ -2485,6 +2489,7 @@ func (Admin) DomainDMARCAddressSave(ctx context.Context, domainName, localpart,
 				Mailbox:   mailbox,
 			}
 		}
+		return nil
 	})
 	xcheckf(ctx, err, "saving dmarc reporting address/settings for domain")
 }
@@ -2493,7 +2498,7 @@ func (Admin) DomainDMARCAddressSave(ctx context.Context, domainName, localpart,
 // configuration for a domain. If localpart is empty, processing reports is
 // disabled.
 func (Admin) DomainTLSRPTAddressSave(ctx context.Context, domainName, localpart, domain, account, mailbox string) {
-	err := mox.DomainSave(ctx, domainName, func(d *config.Domain) {
+	err := mox.DomainSave(ctx, domainName, func(d *config.Domain) error {
 		if localpart == "" {
 			d.TLSRPT = nil
 		} else {
@@ -2504,6 +2509,7 @@ func (Admin) DomainTLSRPTAddressSave(ctx context.Context, domainName, localpart,
 				Mailbox:   mailbox,
 			}
 		}
+		return nil
 	})
 	xcheckf(ctx, err, "saving tls reporting address/settings for domain")
 }
@@ -2511,7 +2517,7 @@ func (Admin) DomainTLSRPTAddressSave(ctx context.Context, domainName, localpart,
 // DomainMTASTSSave saves the MTASTS policy for a domain. If policyID is empty,
 // no MTASTS policy is served.
 func (Admin) DomainMTASTSSave(ctx context.Context, domainName, policyID string, mode mtasts.Mode, maxAge time.Duration, mx []string) {
-	err := mox.DomainSave(ctx, domainName, func(d *config.Domain) {
+	err := mox.DomainSave(ctx, domainName, func(d *config.Domain) error {
 		if policyID == "" {
 			d.MTASTS = nil
 		} else {
@@ -2522,6 +2528,7 @@ func (Admin) DomainMTASTSSave(ctx context.Context, domainName, policyID string,
 				MX:       mx,
 			}
 		}
+		return nil
 	})
 	xcheckf(ctx, err, "saving mtasts policy for domain")
 }
@@ -2557,7 +2564,7 @@ func (Admin) DomainDKIMSave(ctx context.Context, domainName string, selectors ma
 		}
 	}
 
-	err := mox.DomainSave(ctx, domainName, func(d *config.Domain) {
+	err := mox.DomainSave(ctx, domainName, func(d *config.Domain) error {
 		if len(selectors) != len(d.DKIM.Selectors) {
 			xcheckuserf(ctx, fmt.Errorf("cannot add/remove dkim selectors with this function"), "checking selectors")
 		}
@@ -2591,6 +2598,50 @@ func (Admin) DomainDKIMSave(ctx context.Context, domainName string, selectors ma
 			Selectors: sels,
 			Sign:      sign,
 		}
+		return nil
 	})
 	xcheckf(ctx, err, "saving dkim selector for domain")
 }
+
+func xparseAddress(ctx context.Context, lp, domain string) smtp.Address {
+	xlp, err := smtp.ParseLocalpart(lp)
+	xcheckuserf(ctx, err, "parsing localpart")
+	d, err := dns.ParseDomain(domain)
+	xcheckuserf(ctx, err, "parsing domain")
+	return smtp.NewAddress(xlp, d)
+}
+
+func (Admin) AliasAdd(ctx context.Context, aliaslp string, domainName string, alias config.Alias) {
+	addr := xparseAddress(ctx, aliaslp, domainName)
+	err := mox.AliasAdd(ctx, addr, alias)
+	xcheckf(ctx, err, "adding alias")
+}
+
+func (Admin) AliasUpdate(ctx context.Context, aliaslp string, domainName string, postPublic, listMembers, allowMsgFrom bool) {
+	addr := xparseAddress(ctx, aliaslp, domainName)
+	alias := config.Alias{
+		PostPublic:   postPublic,
+		ListMembers:  listMembers,
+		AllowMsgFrom: allowMsgFrom,
+	}
+	err := mox.AliasUpdate(ctx, addr, alias)
+	xcheckf(ctx, err, "saving alias")
+}
+
+func (Admin) AliasRemove(ctx context.Context, aliaslp string, domainName string) {
+	addr := xparseAddress(ctx, aliaslp, domainName)
+	err := mox.AliasRemove(ctx, addr)
+	xcheckf(ctx, err, "removing alias")
+}
+
+func (Admin) AliasAddressesAdd(ctx context.Context, aliaslp string, domainName string, addresses []string) {
+	addr := xparseAddress(ctx, aliaslp, domainName)
+	err := mox.AliasAddressesAdd(ctx, addr, addresses)
+	xcheckf(ctx, err, "adding address to alias")
+}
+
+func (Admin) AliasAddressesRemove(ctx context.Context, aliaslp string, domainName string, addresses []string) {
+	addr := xparseAddress(ctx, aliaslp, domainName)
+	err := mox.AliasAddressesRemove(ctx, addr, addresses)
+	xcheckf(ctx, err, "removing address from alias")
+}