File splitting

3 files changed, 164 insertions, 156 deletions

diff --git a/incoming.go b/incoming.go
new file mode 100644
index 0000000..f915ac0
--- /dev/null
+++ b/incoming.go
@@ -0,0 +1,12 @@
+package main
+
+import "go.lindenii.runxiyu.org/lindenii-common/clog"
+
+func deliver_incoming(envelope_from string, envelope_recipients []string, data []byte) {
+	clog.Debug(
+		"incoming_mail",
+		"envelope_from", envelope_from,
+		"envelope_recipients", envelope_recipients,
+		"data", string(data),
+	)
+}
diff --git a/main.go b/main.go
index d894d8c..8d6b797 100644
--- a/main.go
+++ b/main.go
@@ -2,11 +2,8 @@ package main
 
 import (
 	"bufio"
-	"bytes"
 	"net"
 	"os"
-	"slices"
-	"strings"
 
 	"go.lindenii.runxiyu.org/lindenii-common/clog"
 	"go.lindenii.runxiyu.org/lindenii-common/scfg"
@@ -38,7 +35,7 @@ func main() {
 		}
 
 		go func() {
-			err := handle_connection(bufio.NewReader(conn), bufio.NewWriter(conn))
+			err := handle_incoming_server_connection(bufio.NewReader(conn), bufio.NewWriter(conn))
 			if err != nil {
 				clog.Error("connection handler returned error", "err", err)
 			}
@@ -46,155 +43,3 @@ func main() {
 	}
 
 }
-
-type server_state_t uint
-
-const (
-	server_state_begin server_state_t = iota
-	server_state_helo
-	server_state_mail
-	server_state_rcpt
-)
-
-func handle_connection(reader *bufio.Reader, writer *bufio.Writer) error {
-	_, _ = writer.WriteString("220 " + config.Server_name + " " + VERSION + "\r\n")
-	_ = writer.Flush()
-	server_state := server_state_begin
-	var remote_server_name string
-	var current_mail_from string
-	var current_rcpt_to []string
-	for {
-		line, err := reader.ReadString('\n')
-		if err != nil {
-			return err
-		}
-		line = strings.TrimSuffix(line, "\n")
-		line = strings.TrimSuffix(line, "\r")
-		cmd_end := strings.IndexByte(line, ' ')
-		var param_start int
-		if cmd_end == -1 {
-			cmd_end = len(line)
-			param_start = len(line)
-		} else {
-			param_start = cmd_end + 1
-		}
-		cmd := strings.ToUpper(line[:cmd_end])
-		param := line[param_start:]
-	switch_cmd:
-		switch cmd {
-		case "HELO":
-			if param == "" { // TODO: actually validate the hostname
-				_, _ = writer.WriteString("501 Syntax: HELO hostname\r\n")
-				_ = writer.Flush()
-				break
-			}
-			remote_server_name = param
-			_ = remote_server_name // TODO
-			server_state = server_state_helo
-			_, _ = writer.WriteString("250 " + config.Server_name + "\r\n")
-			_ = writer.Flush()
-		case "MAIL":
-			switch server_state {
-			case server_state_begin:
-				_, _ = writer.WriteString("503 5.5.1 Error: send HELO/EHLO first\r\n")
-				_ = writer.Flush()
-				break switch_cmd
-			case server_state_helo:
-				break
-			case server_state_mail:
-				_, _ = writer.WriteString("503 5.5.1 Error: nested MAIL command\r\n")
-				_ = writer.Flush()
-				break switch_cmd
-			}
-			if len(param) <= len("FROM:") || strings.ToUpper(param[:len("FROM:")]) != "FROM:" {
-				_, _ = writer.WriteString("501 5.5.4 Syntax: MAIL FROM:<address>\r\n")
-				_ = writer.Flush()
-				break
-			}
-			current_mail_from = param[len("FROM:"):]
-			current_rcpt_to = []string{}
-			server_state = server_state_mail
-			_, _ = writer.WriteString("250 2.1.0 Ok\r\n")
-			_ = writer.Flush()
-			// TODO: Address validation
-		case "RCPT":
-			if server_state != server_state_mail && server_state != server_state_rcpt {
-				_, _ = writer.WriteString("503 5.5.1 Error: need MAIL command\r\n")
-				_ = writer.Flush()
-				break
-			}
-			if len(param) <= len("TO:") || strings.ToUpper(param[:len("TO:")]) != "TO:" {
-				_, _ = writer.WriteString("501 5.5.4 Syntax: RCPT TO:<address>\r\n")
-				_ = writer.Flush()
-				break
-			}
-			current_rcpt_to = append(current_rcpt_to, param[len("TO:"):])
-			server_state = server_state_rcpt
-			_, _ = writer.WriteString("250 2.1.5 Ok\r\n")
-			_ = writer.Flush()
-		case "DATA":
-			if server_state != server_state_rcpt {
-				_, _ = writer.WriteString("503 5.5.1 Error: need RCPT command\r\n")
-				_ = writer.Flush()
-				break
-			}
-			_, _ = writer.WriteString("354 End data with <CR><LF>.<CR><LF>\r\n")
-			_ = writer.Flush()
-			var current_data []byte
-			for {
-				tmp, err := reader.ReadSlice('\r')
-				if err != nil {
-					return err
-				}
-
-				// reader.ReadSlice returns an internal buffer that gets
-				// overwritten on the next reader operation. So we must
-				// make a copy; also we have to allocate data_part to
-				// the correct length because [[builtin.copy]] copies
-				// min(len(dst), len(src)) items.
-				data_part := make([]byte, len(tmp))
-				copy(data_part, tmp)
-
-				next_four, err := reader.Peek(4)
-				if err != nil {
-					return err
-				}
-				if bytes.Equal(next_four, []byte{'\n', '.', '\r', '\n'}) {
-					current_data = slices.Concat(current_data, data_part[:len(data_part)-1])
-					break
-				}
-				current_data = slices.Concat(current_data, data_part)
-			}
-			_, err := reader.Discard(4)
-			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")
-			_ = writer.Flush()
-		case "QUIT":
-			_, _ = writer.WriteString("221 2.0.0 Bye\r\n")
-			_ = writer.Flush()
-			return nil
-		case "RSET":
-			if server_state != server_state_begin {
-				server_state = server_state_helo
-			}
-			_, _ = writer.WriteString("250 2.0.0 Ok\r\n")
-			_ = writer.Flush()
-		default:
-			_, _ = writer.WriteString("500 5.5.2 Error: command not recognized\r\n")
-			_ = writer.Flush()
-		}
-	}
-}
-
-func deliver_incoming(envelope_from string, envelope_recipients []string, data []byte) {
-	clog.Debug(
-		"incoming_mail",
-		"envelope_from", envelope_from,
-		"envelope_recipients", envelope_recipients,
-		"data", string(data),
-	)
-}
diff --git a/mta_recv.go b/mta_recv.go
new file mode 100644
index 0000000..2b4679a
--- /dev/null
+++ b/mta_recv.go
@@ -0,0 +1,151 @@
+package main
+
+import (
+	"bufio"
+	"bytes"
+	"slices"
+	"strings"
+)
+
+type server_state_t uint
+
+const (
+	server_state_begin server_state_t = iota
+	server_state_helo
+	server_state_mail
+	server_state_rcpt
+)
+
+func handle_incoming_server_connection(reader *bufio.Reader, writer *bufio.Writer) error {
+	_, _ = writer.WriteString("220 " + config.Server_name + " " + VERSION + "\r\n")
+	_ = writer.Flush()
+	server_state := server_state_begin
+	var remote_server_name string
+	var current_mail_from string
+	var current_rcpt_to []string
+	for {
+		line, err := reader.ReadString('\n')
+		if err != nil {
+			return err
+		}
+		line = strings.TrimSuffix(line, "\n")
+		line = strings.TrimSuffix(line, "\r")
+		cmd_end := strings.IndexByte(line, ' ')
+		var param_start int
+		if cmd_end == -1 {
+			cmd_end = len(line)
+			param_start = len(line)
+		} else {
+			param_start = cmd_end + 1
+		}
+		cmd := strings.ToUpper(line[:cmd_end])
+		param := line[param_start:]
+	switch_cmd:
+		switch cmd {
+		case "HELO":
+			if param == "" { // TODO: actually validate the hostname
+				_, _ = writer.WriteString("501 Syntax: HELO hostname\r\n")
+				_ = writer.Flush()
+				break
+			}
+			remote_server_name = param
+			_ = remote_server_name // TODO
+			server_state = server_state_helo
+			_, _ = writer.WriteString("250 " + config.Server_name + "\r\n")
+			_ = writer.Flush()
+		case "MAIL":
+			switch server_state {
+			case server_state_begin:
+				_, _ = writer.WriteString("503 5.5.1 Error: send HELO/EHLO first\r\n")
+				_ = writer.Flush()
+				break switch_cmd
+			case server_state_helo:
+				break
+			case server_state_mail:
+				_, _ = writer.WriteString("503 5.5.1 Error: nested MAIL command\r\n")
+				_ = writer.Flush()
+				break switch_cmd
+			}
+			if len(param) <= len("FROM:") || strings.ToUpper(param[:len("FROM:")]) != "FROM:" {
+				_, _ = writer.WriteString("501 5.5.4 Syntax: MAIL FROM:<address>\r\n")
+				_ = writer.Flush()
+				break
+			}
+			current_mail_from = param[len("FROM:"):]
+			current_rcpt_to = []string{}
+			server_state = server_state_mail
+			_, _ = writer.WriteString("250 2.1.0 Ok\r\n")
+			_ = writer.Flush()
+			// TODO: Address validation
+		case "RCPT":
+			if server_state != server_state_mail && server_state != server_state_rcpt {
+				_, _ = writer.WriteString("503 5.5.1 Error: need MAIL command\r\n")
+				_ = writer.Flush()
+				break
+			}
+			if len(param) <= len("TO:") || strings.ToUpper(param[:len("TO:")]) != "TO:" {
+				_, _ = writer.WriteString("501 5.5.4 Syntax: RCPT TO:<address>\r\n")
+				_ = writer.Flush()
+				break
+			}
+			current_rcpt_to = append(current_rcpt_to, param[len("TO:"):])
+			server_state = server_state_rcpt
+			_, _ = writer.WriteString("250 2.1.5 Ok\r\n")
+			_ = writer.Flush()
+		case "DATA":
+			if server_state != server_state_rcpt {
+				_, _ = writer.WriteString("503 5.5.1 Error: need RCPT command\r\n")
+				_ = writer.Flush()
+				break
+			}
+			_, _ = writer.WriteString("354 End data with <CR><LF>.<CR><LF>\r\n")
+			_ = writer.Flush()
+			var current_data []byte
+			for {
+				tmp, err := reader.ReadSlice('\r')
+				if err != nil {
+					return err
+				}
+
+				// reader.ReadSlice returns an internal buffer that gets
+				// overwritten on the next reader operation. So we must
+				// make a copy; also we have to allocate data_part to
+				// the correct length because [[builtin.copy]] copies
+				// min(len(dst), len(src)) items.
+				data_part := make([]byte, len(tmp))
+				copy(data_part, tmp)
+
+				next_four, err := reader.Peek(4)
+				if err != nil {
+					return err
+				}
+				if bytes.Equal(next_four, []byte{'\n', '.', '\r', '\n'}) {
+					current_data = slices.Concat(current_data, data_part[:len(data_part)-1])
+					break
+				}
+				current_data = slices.Concat(current_data, data_part)
+			}
+			_, err := reader.Discard(4)
+			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")
+			_ = writer.Flush()
+		case "QUIT":
+			_, _ = writer.WriteString("221 2.0.0 Bye\r\n")
+			_ = writer.Flush()
+			return nil
+		case "RSET":
+			if server_state != server_state_begin {
+				server_state = server_state_helo
+			}
+			_, _ = writer.WriteString("250 2.0.0 Ok\r\n")
+			_ = writer.Flush()
+		default:
+			_, _ = writer.WriteString("500 5.5.2 Error: command not recognized\r\n")
+			_ = writer.Flush()
+		}
+	}
+}