policy: Implement recipient domain policy for #51

- INBUCKET_SMTP_DEFAULTACCEPT
- INBUCKET_SMTP_ACCEPTDOMAINS
- INBUCKET_SMTP_REJECTDOMAINS

pkg/policy/address.go

@@ -7,6 +7,7 @@ import (
 	"strings"
 
 	"github.com/jhillyerd/inbucket/pkg/config"
+	"github.com/jhillyerd/inbucket/pkg/stringutil"
 )
 
 // Addressing handles email address policy.
@@ -29,14 +30,26 @@ func (a *Addressing) NewRecipient(address string) (*Recipient, error) {
 		return nil, err
 	}
 	return &Recipient{
-		Address:   *ar,
-		apolicy:   a,
-		LocalPart: local,
-		Domain:    domain,
-		Mailbox:   mailbox,
+		Address:    *ar,
+		addrPolicy: a,
+		LocalPart:  local,
+		Domain:     domain,
+		Mailbox:    mailbox,
 	}, nil
 }
 
+// ShouldAcceptDomain indicates if Inbucket accepts mail destined for the specified domain.
+func (a *Addressing) ShouldAcceptDomain(domain string) bool {
+	domain = strings.ToLower(domain)
+	if a.Config.DefaultAccept && !stringutil.SliceContains(a.Config.RejectDomains, domain) {
+		return true
+	}
+	if !a.Config.DefaultAccept && stringutil.SliceContains(a.Config.AcceptDomains, domain) {
+		return true
+	}
+	return false
+}
+
 // ShouldStoreDomain indicates if Inbucket stores email destined for the specified domain.
 func (a *Addressing) ShouldStoreDomain(domain string) bool {
 	if a.Config.StoreMessages {

pkg/policy/address_test.go

@@ -8,6 +8,59 @@ import (
 	"github.com/jhillyerd/inbucket/pkg/policy"
 )
 
+func TestShouldAcceptDomain(t *testing.T) {
+	// Test with default accept.
+	ap := &policy.Addressing{
+		Config: config.SMTP{
+			DefaultAccept: true,
+			RejectDomains: []string{"a.deny.com", "deny.com"},
+		},
+	}
+	testCases := []struct {
+		domain string
+		want   bool
+	}{
+		{domain: "bar.com", want: true},
+		{domain: "DENY.com", want: false},
+		{domain: "a.deny.com", want: false},
+		{domain: "b.deny.com", want: true},
+	}
+	for _, tc := range testCases {
+		t.Run(tc.domain, func(t *testing.T) {
+			got := ap.ShouldAcceptDomain(tc.domain)
+			if got != tc.want {
+				t.Errorf("Got %v for %q, want: %v", got, tc.domain, tc.want)
+			}
+
+		})
+	}
+	// Test with default reject.
+	ap = &policy.Addressing{
+		Config: config.SMTP{
+			DefaultAccept: false,
+			AcceptDomains: []string{"a.allow.com", "allow.com"},
+		},
+	}
+	testCases = []struct {
+		domain string
+		want   bool
+	}{
+		{domain: "bar.com", want: false},
+		{domain: "ALLOW.com", want: true},
+		{domain: "a.allow.com", want: true},
+		{domain: "b.allow.com", want: false},
+	}
+	for _, tc := range testCases {
+		t.Run(tc.domain, func(t *testing.T) {
+			got := ap.ShouldAcceptDomain(tc.domain)
+			if got != tc.want {
+				t.Errorf("Got %v for %q, want: %v", got, tc.domain, tc.want)
+			}
+
+		})
+	}
+}
+
 func TestShouldStoreDomain(t *testing.T) {
 	// Test with storage enabled.
 	ap := &policy.Addressing{

pkg/policy/recipient.go

@@ -5,7 +5,7 @@ import "net/mail"
 // Recipient represents a potential email recipient, allows policies for it to be queried.
 type Recipient struct {
 	mail.Address
-	apolicy *Addressing
+	addrPolicy *Addressing
 	// LocalPart is the part of the address before @, including +extension.
 	LocalPart string
 	// Domain is the part of the address after @.
@@ -16,10 +16,10 @@ type Recipient struct {
 
 // ShouldAccept returns true if Inbucket should accept mail for this recipient.
 func (r *Recipient) ShouldAccept() bool {
-	return true
+	return r.addrPolicy.ShouldAcceptDomain(r.Domain)
 }
 
 // ShouldStore returns true if Inbucket should store mail for this recipient.
 func (r *Recipient) ShouldStore() bool {
-	return r.apolicy.ShouldStoreDomain(r.Domain)
+	return r.addrPolicy.ShouldStoreDomain(r.Domain)
 }