Introduce an "envelope" package

This patch introduces an "envelope" package which, for now, provides simple
utilities for getting the user and domain of an address.

It also changes the couriers to use it (but other implementations remain, will
be moved over in subsequent patches).

internal/courier/courier.go

@@ -1,7 +1,7 @@
 // Package courier implements various couriers for delivering messages.
 package courier
 
-import "strings"
+import "blitiri.com.ar/go/chasquid/internal/envelope"
 
 // Courier delivers mail to a single recipient.
 // It is implemented by different couriers, for both local and remote
@@ -19,30 +19,10 @@ type Router struct {
 }
 
 func (r *Router) Deliver(from string, to string, data []byte) error {
-	d := domainOf(to)
+	d := envelope.DomainOf(to)
 	if r.LocalDomains[d] {
 		return r.Local.Deliver(from, to, data)
 	} else {
 		return r.Remote.Deliver(from, to, data)
 	}
 }
-
-// Split an user@domain address into user and domain.
-func split(addr string) (string, string) {
-	ps := strings.SplitN(addr, "@", 2)
-	if len(ps) != 2 {
-		return addr, ""
-	}
-
-	return ps[0], ps[1]
-}
-
-func userOf(addr string) string {
-	user, _ := split(addr)
-	return user
-}
-
-func domainOf(addr string) string {
-	_, domain := split(addr)
-	return domain
-}

internal/courier/procmail.go

@@ -8,6 +8,7 @@ import (
 	"time"
 	"unicode"
 
+	"blitiri.com.ar/go/chasquid/internal/envelope"
 	"blitiri.com.ar/go/chasquid/internal/trace"
 )
 
@@ -36,13 +37,17 @@ func (p *Procmail) Deliver(from string, to string, data []byte) error {
 	defer tr.Finish()
 
 	// Get the user, and sanitize to be extra paranoid.
-	user := sanitizeForProcmail(userOf(to))
+	user := sanitizeForProcmail(envelope.UserOf(to))
-	tr.LazyPrintf("%s  ->  %s (%s)", from, user, to)
+	domain := sanitizeForProcmail(envelope.DomainOf(to))
+	tr.LazyPrintf("%s  ->  %s (%s @ %s)", from, user, to, domain)
 
 	// Prepare the command, replacing the necessary arguments.
+	replacer := strings.NewReplacer(
+		"%user%", user,
+		"%domain%", domain)
 	args := []string{}
 	for _, a := range MailDeliveryAgentArgs {
-		args = append(args, strings.Replace(a, "%user%", user, -1))
+		args = append(args, replacer.Replace(a))
 	}
 	cmd := exec.Command(MailDeliveryAgentBin, args...)
 

internal/courier/procmail_test.go

@@ -19,7 +19,8 @@ func TestProcmail(t *testing.T) {
 	MailDeliveryAgentArgs = []string{dir + "/%user%"}
 
 	p := Procmail{}
-	err = p.Deliver("from@x", "to@y", []byte("data"))
+
+	err = p.Deliver("from@x", "to@local", []byte("data"))
 	if err != nil {
 		t.Fatalf("Deliver: %v", err)
 	}
@@ -36,7 +37,8 @@ func TestProcmailTimeout(t *testing.T) {
 	procmailTimeout = 100 * time.Millisecond
 
 	p := Procmail{}
-	err := p.Deliver("from", "to", []byte("data"))
+
+	err := p.Deliver("from", "to@local", []byte("data"))
 	if err != timeoutError {
 		t.Errorf("Unexpected error: %v", err)
 	}

internal/courier/smtp.go

@@ -8,6 +8,7 @@ import (
 
 	"github.com/golang/glog"
 
+	"blitiri.com.ar/go/chasquid/internal/envelope"
 	"blitiri.com.ar/go/chasquid/internal/trace"
 )
 
@@ -33,7 +34,7 @@ func (s *SMTP) Deliver(from string, to string, data []byte) error {
 	defer tr.Finish()
 	tr.LazyPrintf("%s  ->  %s", from, to)
 
-	mx, err := lookupMX(domainOf(to))
+	mx, err := lookupMX(envelope.DomainOf(to))
 	if err != nil {
 		return tr.Errorf("Could not find mail server: %v", err)
 	}

internal/envelope/envelope.go

@@ -0,0 +1,38 @@
+// Package envelope implements functions related to handling email envelopes
+// (basically tuples of (from, to, data).
+package envelope
+
+import (
+	"strings"
+
+	"blitiri.com.ar/go/chasquid/internal/set"
+)
+
+// Split an user@domain address into user and domain.
+func split(addr string) (string, string) {
+	ps := strings.SplitN(addr, "@", 2)
+	if len(ps) != 2 {
+		return addr, ""
+	}
+
+	return ps[0], ps[1]
+}
+
+func UserOf(addr string) string {
+	user, _ := split(addr)
+	return user
+}
+
+func DomainOf(addr string) string {
+	_, domain := split(addr)
+	return domain
+}
+
+func DomainIn(addr string, locals *set.String) bool {
+	domain := DomainOf(addr)
+	if domain == "" {
+		return true
+	}
+
+	return locals.Has(domain)
+}

internal/envelope/envelope_test.go

@@ -0,0 +1,43 @@
+package envelope
+
+import (
+	"testing"
+
+	"blitiri.com.ar/go/chasquid/internal/set"
+)
+
+func TestSplit(t *testing.T) {
+	cases := []struct {
+		addr, user, domain string
+	}{
+		{"lalala@lelele", "lalala", "lelele"},
+	}
+
+	for _, c := range cases {
+		if user := UserOf(c.addr); user != c.user {
+			t.Errorf("%q: expected user %q, got %q", c.addr, c.user, user)
+		}
+		if domain := DomainOf(c.addr); domain != c.domain {
+			t.Errorf("%q: expected domain %q, got %q",
+				c.addr, c.domain, domain)
+		}
+	}
+}
+
+func TestDomainIn(t *testing.T) {
+	ls := set.NewString("domain1", "domain2")
+	cases := []struct {
+		addr string
+		in   bool
+	}{
+		{"u@domain1", true},
+		{"u@domain2", true},
+		{"u@domain3", false},
+		{"u", true},
+	}
+	for _, c := range cases {
+		if in := DomainIn(c.addr, ls); in != c.in {
+			t.Errorf("%q: expected %v, got %v", c.addr, c.in, in)
+		}
+	}
+}