Give explicit notice on message truncation.

Fixes #1

2 files changed, 51 insertions, 7 deletions

diff --git a/irc/irc.go b/irc/irc.go
index 24f9d3d..b4505af 100644
--- a/irc/irc.go
+++ b/irc/irc.go
@@ -11,6 +11,7 @@ import (
 	"net"
 	"sync"
 	"time"
+	"unicode/utf8"
 
 	"github.com/arachnist/dyncfg"
 )
@@ -39,9 +40,28 @@ type Connection struct {
 func (c *Connection) Sender(msg Message) {
 	c.l.Lock()
 	defer c.l.Unlock()
-	c.writer.WriteString(msg.String() + endline)
-	log.Println(c.network, "-->", msg.String())
-	c.writer.Flush()
+	if msg.WireLen() > maxLength {
+		currLen := 0
+		for i, ch := range msg.String() {
+			currLen += utf8.RuneLen(ch)
+			if currLen > maxLength {
+				c.writer.WriteString(msg.String()[:i] + endline)
+				log.Println(c.network, "-->", msg.String())
+				c.writer.Flush()
+				// eh, it is a bit naive to assume that we won't explode again…
+				if msg.Command == "PRIVMSG" { // we don't care otherwise
+					newMsg := msg
+					newMsg.Trailing = "Message truncated"
+					go c.Sender(newMsg)
+				}
+				return
+			}
+		}
+	} else {
+		c.writer.WriteString(msg.String() + endline)
+		log.Println(c.network, "-->", msg.String())
+		c.writer.Flush()
+	}
 }
 
 // Receiver receives IRC messages from server, logs their contents, sets message
diff --git a/irc/message.go b/irc/message.go
index 2f8971a..e1d448b 100644
--- a/irc/message.go
+++ b/irc/message.go
@@ -288,12 +288,36 @@ func (m *Message) Bytes() []byte {
 		buffer.WriteString(m.Trailing)
 	}
 
-	// We need the limit the buffer length.
-	if buffer.Len() > (maxLength) {
-		buffer.Truncate(maxLength)
+	return buffer.Bytes()
+}
+
+func (m *Message) WireLen() int {
+
+	buffer := new(bytes.Buffer)
+
+	// Message prefix
+	if m.Prefix != nil {
+		buffer.WriteByte(prefix)
+		m.Prefix.writeTo(buffer)
+		buffer.WriteByte(space)
 	}
 
-	return buffer.Bytes()
+	// Command is required
+	buffer.WriteString(m.Command)
+
+	// Space separated list of arguments
+	if len(m.Params) > 0 {
+		buffer.WriteByte(space)
+		buffer.WriteString(strings.Join(m.Params, string(space)))
+	}
+
+	if len(m.Trailing) > 0 || m.EmptyTrailing {
+		buffer.WriteByte(space)
+		buffer.WriteByte(prefix)
+		buffer.WriteString(m.Trailing)
+	}
+
+	return buffer.Len()
 }
 
 // String returns a string representation of this message.