Add basic routing

8 files changed, 66 insertions, 49 deletions

diff --git a/BUGS b/BUGS
new file mode 100644
index 0000000..3f83851
--- /dev/null
+++ b/BUGS
@@ -0,0 +1,2 @@
+There might be standard library functions that use runes instead of bytes while
+operating over strings.
diff --git a/config.go b/config.go
index 8ba30ad..f187b69 100644
--- a/config.go
+++ b/config.go
@@ -3,16 +3,14 @@ package main
 import (
 	"bufio"
 	"os"
-	"reflect"
 	"sync"
 
-	"go.lindenii.runxiyu.org/lindenii-common/misc"
 	"go.lindenii.runxiyu.org/lindenii-common/scfg"
 )
 
 var config struct {
-	Server_name string `scfg:"server_name"`
-	Inbox_path  string `scfg:"inbox_path"`
+	Server_name string            `scfg:"server_name"`
+	Routes      map[string]string `scfg:"routes"`
 }
 var config_mutex sync.RWMutex
 
@@ -36,34 +34,20 @@ func load_config(path string) error {
 	return nil
 }
 
-var directories struct {
-	inbox misc.Dir_t
+// config_fetch_one fetches one value from the configuration.
+//
+// Consequtive calls do not guarantee a consistent snapshot of the
+// configuration. Use config_consistent_run in these cases.
+func config_fetch_one[T any](x *T) T {
+	config_mutex.RLock()
+	defer config_mutex.RUnlock()
+	return *x
 }
-var directories_mutex sync.RWMutex
 
-func prepare_dirs() error {
-	directories_mutex.Lock()
-	defer directories_mutex.Unlock()
-	var err error
-	directories.inbox, err = misc.Open_directory_readonly(config.Inbox_path)
-	if err != nil {
-		return err
-	}
-	return nil
-}
-
-// clean_up_dirs closes all directories. It should only be called before
-// program exit.
-func clean_up_dirs() {
-	directories_mutex.Lock()
-	defer directories_mutex.Unlock()
-	directories_rv := reflect.ValueOf(directories)
-	directories_rt := directories_rv.Type()
-	for i := range directories_rt.NumField() {
-		dir, ok := directories_rv.Field(i).Interface().(misc.Dir_t)
-		if !ok {
-			panic("directories contains a field that's not misc.Dir_t")
-		}
-		dir.Close()
-	}
+// config_consistent_run runs the supplied function with a consistent snapshot
+// of the configuration.
+func config_consistent_run(f func()) {
+	config_mutex.RLock()
+	defer config_mutex.RUnlock()
+	f()
 }
diff --git a/go.mod b/go.mod
index 5ea39e0..314be8d 100644
--- a/go.mod
+++ b/go.mod
@@ -2,4 +2,4 @@ module go.lindenii.runxiyu.org/maild
 
 go 1.23.4
 
-require go.lindenii.runxiyu.org/lindenii-common v0.0.0-20250104140324-f57ba68adb4d
+require go.lindenii.runxiyu.org/lindenii-common v0.0.0-20250111202249-35d69905e2fc
diff --git a/go.sum b/go.sum
index 1d1725c..3e0ed5e 100644
--- a/go.sum
+++ b/go.sum
@@ -1,2 +1,2 @@
-go.lindenii.runxiyu.org/lindenii-common v0.0.0-20250104140324-f57ba68adb4d h1:ilNgswXXIKwDK/8xvV0UH6FNZ1XpZHxm3s381xz2icM=
-go.lindenii.runxiyu.org/lindenii-common v0.0.0-20250104140324-f57ba68adb4d/go.mod h1:bOxuuGXA3UpbLb1lKohr2j2MVcGGLcqfAprGx9VCkMA=
+go.lindenii.runxiyu.org/lindenii-common v0.0.0-20250111202249-35d69905e2fc h1:jYjxxslcbZSKmXT96FhRW//t0dx9LN54J4PeD6oXTQk=
+go.lindenii.runxiyu.org/lindenii-common v0.0.0-20250111202249-35d69905e2fc/go.mod h1:bOxuuGXA3UpbLb1lKohr2j2MVcGGLcqfAprGx9VCkMA=
diff --git a/incoming.go b/incoming.go
index 35aa006..e672587 100644
--- a/incoming.go
+++ b/incoming.go
@@ -8,7 +8,7 @@ import (
 	"go.lindenii.runxiyu.org/lindenii-common/misc"
 )
 
-func deliver_incoming(envelope_from string, envelope_recipients []string, data []byte) error {
+func deliver_incoming(envelope_from string, envelope_recipients []string, data []byte, dir_path string) error {
 	clog.Debug(
 		"incoming_mail",
 		"envelope_from", envelope_from,
@@ -16,7 +16,11 @@ func deliver_incoming(envelope_from string, envelope_recipients []string, data [
 		"data", string(data),
 	)
 	t := time.Now()
-	fd, err := misc.Open_file_at(directories.inbox, envelope_from+" "+t.Format(time.RFC3339Nano)+".eml", os.O_CREATE|os.O_EXCL|os.O_WRONLY, 0o600)
+	dir, err := misc.Open_directory_readonly(dir_path)
+	if err != nil {
+		return misc.Wrap_one_error(err_deliver_write, err)
+	}
+	fd, err := misc.Open_file_at(dir, envelope_from+" "+t.Format(time.RFC3339Nano)+".eml", os.O_CREATE|os.O_EXCL|os.O_WRONLY, 0o600)
 	if err != nil {
 		// TODO: handle fs.ErrExist
 		return misc.Wrap_one_error(err_deliver_write, err)
diff --git a/maild.scfg b/maild.scfg
index 84c613e..99efe9c 100644
--- a/maild.scfg
+++ b/maild.scfg
@@ -1,2 +1,7 @@
 server_name mail.andrewyu.org
-inbox_path  /home/runxiyu/inbox
+
+routes {
+        andrew@andrewyu.org /home/runxiyu/inbox
+        test@andrewyu.org /home/runxiyu/inbox
+        adeline@andrewyu.org /home/runxiyu/inbox
+}
diff --git a/main.go b/main.go
index f71391d..94f195e 100644
--- a/main.go
+++ b/main.go
@@ -19,12 +19,6 @@ func main() {
 		panic(err)
 	}
 
-	err = prepare_dirs()
-	if err != nil {
-		panic(err)
-	}
-	defer clean_up_dirs()
-
 	listener, err := net.Listen("tcp", ":25")
 	if err != nil {
 		panic(err)
diff --git a/mta_recv.go b/mta_recv.go
index fe6139f..d5a14ed 100644
--- a/mta_recv.go
+++ b/mta_recv.go
@@ -5,6 +5,8 @@ import (
 	"bytes"
 	"slices"
 	"strings"
+
+	"go.lindenii.runxiyu.org/lindenii-common/mailkit"
 )
 
 type server_state_t uint
@@ -17,7 +19,13 @@ const (
 )
 
 func handle_incoming_server_connection(reader *bufio.Reader, writer *bufio.Writer) error {
-	_, _ = writer.WriteString("220 " + config.Server_name + " " + VERSION + "\r\n")
+	var my_server_name string
+	var routes map[string]string
+	config_consistent_run(func() {
+		my_server_name = config.Server_name
+		routes = config.Routes
+	})
+	_, _ = writer.WriteString("220 " + my_server_name + " " + VERSION + "\r\n")
 	_ = writer.Flush()
 	server_state := server_state_begin
 	var remote_server_name string
@@ -51,7 +59,7 @@ func handle_incoming_server_connection(reader *bufio.Reader, writer *bufio.Write
 			remote_server_name = param
 			_ = remote_server_name // TODO
 			server_state = server_state_helo
-			_, _ = writer.WriteString("250 " + config.Server_name + "\r\n")
+			_, _ = writer.WriteString("250 " + my_server_name + "\r\n")
 			_ = writer.Flush()
 		case "MAIL":
 			switch server_state {
@@ -88,7 +96,14 @@ func handle_incoming_server_connection(reader *bufio.Reader, writer *bufio.Write
 				_ = writer.Flush()
 				break
 			}
-			current_rcpt_to = append(current_rcpt_to, param[len("TO:"):])
+			recipient, _, _ := mailkit.Strip_angle_brackets(param[len("TO:"):])
+			_, ok := routes[recipient]
+			if !ok {
+				_, _ = writer.WriteString("550 5.1.1 <" + recipient + ">: Recipient address rejected: User unknown in local recipient table\r\n")
+				_ = writer.Flush()
+				break switch_cmd
+			}
+			current_rcpt_to = append(current_rcpt_to, recipient)
 			server_state = server_state_rcpt
 			_, _ = writer.WriteString("250 2.1.5 Ok\r\n")
 			_ = writer.Flush()
@@ -129,11 +144,24 @@ func handle_incoming_server_connection(reader *bufio.Reader, writer *bufio.Write
 			if err != nil {
 				return err
 			}
-			err = deliver_incoming(current_mail_from, current_rcpt_to, current_data)
+			{
+				inboxes_to_deliver_to := make(map[string]struct{})
+				for _, recipient := range current_rcpt_to {
+					inbox, ok := routes[recipient]
+					if !ok {
+						_, _ = writer.WriteString("550 5.1.1 <" + recipient + ">: Recipient address rejected: User unknown in local recipient table\r\n")
+						break switch_cmd
+					}
+					inboxes_to_deliver_to[inbox] = struct{}{}
+				}
+				for inbox := range inboxes_to_deliver_to {
+					err = deliver_incoming(current_mail_from, current_rcpt_to, current_data, inbox)
+				}
+			}
 			if err == nil {
 				_, _ = writer.WriteString("250 2.0.0 Ok: Accepted\r\n")
 			} else {
-				_, _ = writer.WriteString("500 2.0.0 Error: "+err.Error()+"\r\n")
+				_, _ = writer.WriteString("500 2.0.0 Error: " + err.Error() + "\r\n")
 			}
 			_ = writer.Flush()
 			server_state = server_state_helo