From 00f3cb9fb48cfb9768b695bd0d9eb8367ad84782 Mon Sep 17 00:00:00 2001
From: Runxi Yu <me@runxiyu.org>
Date: Thu, 2 Jan 2025 19:30:51 +0000
Subject: Deliver to inbox

---
 config.go   | 29 ++++++++++++++++++++++++++++-
 errors.go   |  9 +++++++++
 incoming.go | 20 ++++++++++++++++++--
 maild.scfg  |  1 +
 main.go     | 15 ++++++---------
 mta_recv.go | 10 +++++++---
 6 files changed, 69 insertions(+), 15 deletions(-)
 create mode 100644 errors.go

diff --git a/config.go b/config.go
index 1a89987..c4b5579 100644
--- a/config.go
+++ b/config.go
@@ -1,7 +1,34 @@
 package main
 
+import (
+	"bufio"
+	"go.lindenii.runxiyu.org/lindenii-common/scfg"
+	"os"
+	"sync"
+)
+
 var config struct {
 	Server_name string `scfg:"server_name"`
+	Inbox_path string `scfg:"inbox_path"`
 }
+var config_mutex sync.RWMutex
 
-// TODO: edit scfg to require fields to exist unless explicitly marked optional.
+func load_config(path string) error {
+	config_file, err := os.Open(path)
+	if err != nil {
+		return err
+	}
+	decoder := scfg.NewDecoder(bufio.NewReader(config_file))
+	if func() error {
+		config_mutex.Lock()
+		defer config_mutex.Unlock()
+		err = decoder.Decode(&config)
+		if err != nil {
+			return err
+		}
+		return nil
+	}() != nil {
+		return err
+	}
+	return nil
+}
diff --git a/errors.go b/errors.go
new file mode 100644
index 0000000..0d6a8d7
--- /dev/null
+++ b/errors.go
@@ -0,0 +1,9 @@
+package main
+
+import (
+	"errors"
+)
+
+var (
+	err_deliver_write = errors.New("unable to write to filesystem while attempting to deliver message")
+)
diff --git a/incoming.go b/incoming.go
index f915ac0..169bde5 100644
--- a/incoming.go
+++ b/incoming.go
@@ -1,12 +1,28 @@
 package main
 
-import "go.lindenii.runxiyu.org/lindenii-common/clog"
+import (
+	"go.lindenii.runxiyu.org/lindenii-common/clog"
+	"os"
+	"path"
+	"time"
+)
 
-func deliver_incoming(envelope_from string, envelope_recipients []string, data []byte) {
+func deliver_incoming(envelope_from string, envelope_recipients []string, data []byte) error {
 	clog.Debug(
 		"incoming_mail",
 		"envelope_from", envelope_from,
 		"envelope_recipients", envelope_recipients,
 		"data", string(data),
 	)
+	t := time.Now()
+	fd, err := os.OpenFile(path.Join(config.Inbox_path, envelope_from+" "+t.Format(time.RFC3339Nano)+".eml"), os.O_CREATE|os.O_EXCL|os.O_WRONLY, 0660) // TODO: vulnerability
+	if err != nil {
+		// TODO: handle fs.ErrExist
+		return err_deliver_write
+	}
+	_, err = fd.Write(data)
+	if err != nil {
+		return err_deliver_write
+	}
+	return nil
 }
diff --git a/maild.scfg b/maild.scfg
index 24f7b84..84c613e 100644
--- a/maild.scfg
+++ b/maild.scfg
@@ -1 +1,2 @@
 server_name mail.andrewyu.org
+inbox_path  /home/runxiyu/inbox
diff --git a/main.go b/main.go
index 8d6b797..052deec 100644
--- a/main.go
+++ b/main.go
@@ -3,21 +3,18 @@ package main
 import (
 	"bufio"
 	"net"
-	"os"
+	"flag"
+	"errors"
+	"io"
 
 	"go.lindenii.runxiyu.org/lindenii-common/clog"
-	"go.lindenii.runxiyu.org/lindenii-common/scfg"
 )
 
 const VERSION = "lindenii-maild v0.0.0"
 
 func main() {
-	config_file, err := os.Open("maild.scfg")
-	if err != nil {
-		panic(err)
-	}
-
-	err = scfg.NewDecoder(bufio.NewReader(config_file)).Decode(&config)
+	config_path := flag.String("config", "maild.scfg", "path to configuration file")
+	err := load_config(*config_path)
 	if err != nil {
 		panic(err)
 	}
@@ -36,7 +33,7 @@ func main() {
 
 		go func() {
 			err := handle_incoming_server_connection(bufio.NewReader(conn), bufio.NewWriter(conn))
-			if err != nil {
+			if err != nil && !errors.Is(err, io.EOF) {
 				clog.Error("connection handler returned error", "err", err)
 			}
 		}()
diff --git a/mta_recv.go b/mta_recv.go
index 2b4679a..c77c46d 100644
--- a/mta_recv.go
+++ b/mta_recv.go
@@ -129,10 +129,14 @@ func handle_incoming_server_connection(reader *bufio.Reader, writer *bufio.Write
 			if err != nil {
 				return err
 			}
-			deliver_incoming(current_mail_from, current_rcpt_to, current_data)
-			server_state = server_state_helo
-			_, _ = writer.WriteString("250 2.0.0 Ok: Accepted\r\n")
+			err = deliver_incoming(current_mail_from, current_rcpt_to, current_data)
+			if err == nil {
+				_, _ = writer.WriteString("250 2.0.0 Ok: Accepted\r\n")
+			} else {
+				_, _ = writer.WriteString("500 2.0.0 Funderscore\r\n")
+			}
 			_ = writer.Flush()
+			server_state = server_state_helo
 		case "QUIT":
 			_, _ = writer.WriteString("221 2.0.0 Bye\r\n")
 			_ = writer.Flush()
-- 
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