From 4b81d501ccc5e2168b3fd717553474807e5038d8 Mon Sep 17 00:00:00 2001
From: Shivaram Lingamneni <slingamn@cs.stanford.edu>
Date: Fri, 23 Apr 2021 11:14:48 -0400
Subject: [PATCH 1/2] ircevent: add AllowTruncation

---
 ircevent/irc.go        |  2 +-
 ircevent/irc_struct.go | 45 +++++++++++++++++++++---------------------
 2 files changed, 24 insertions(+), 23 deletions(-)

diff --git a/ircevent/irc.go b/ircevent/irc.go
index 1b4ac5c..ac3a34c 100644
--- a/ircevent/irc.go
+++ b/ircevent/irc.go
@@ -351,7 +351,7 @@ func (irc *Connection) sendInternal(b []byte) (err error) {
 // Send a built ircmsg.Message.
 func (irc *Connection) SendIRCMessage(msg ircmsg.Message) error {
 	b, err := msg.LineBytesStrict(true, irc.MaxLineLen)
-	if err != nil {
+	if err != nil && !(irc.AllowTruncation && err == ircmsg.ErrorBodyTooLong) {
 		if irc.Debug {
 			irc.Log.Printf("couldn't assemble message: %v\n", err)
 		}
diff --git a/ircevent/irc_struct.go b/ircevent/irc_struct.go
index 5c0a238..c0ecdfe 100644
--- a/ircevent/irc_struct.go
+++ b/ircevent/irc_struct.go
@@ -41,28 +41,29 @@ type capResult struct {
 
 type Connection struct {
 	// config data, user-settable
-	Server        string
-	TLSConfig     *tls.Config
-	Nick          string
-	User          string
-	RealName      string   // IRC realname/gecos
-	WebIRC        []string // parameters for the WEBIRC command
-	Password      string   // server password (PASS command)
-	RequestCaps   []string // IRCv3 capabilities to request (failure is non-fatal)
-	SASLLogin     string   // SASL credentials to log in with (failure is fatal)
-	SASLPassword  string
-	SASLMech      string
-	QuitMessage   string
-	Version       string
-	Timeout       time.Duration
-	KeepAlive     time.Duration
-	ReconnectFreq time.Duration
-	MaxLineLen    int // maximum line length, not including tags
-	UseTLS        bool
-	UseSASL       bool
-	EnableCTCP    bool
-	Debug         bool
-	AllowPanic    bool // if set, don't recover() from panics in callbacks
+	Server          string
+	TLSConfig       *tls.Config
+	Nick            string
+	User            string
+	RealName        string   // IRC realname/gecos
+	WebIRC          []string // parameters for the WEBIRC command
+	Password        string   // server password (PASS command)
+	RequestCaps     []string // IRCv3 capabilities to request (failure is non-fatal)
+	SASLLogin       string   // SASL credentials to log in with (failure is fatal)
+	SASLPassword    string
+	SASLMech        string
+	QuitMessage     string
+	Version         string
+	Timeout         time.Duration
+	KeepAlive       time.Duration
+	ReconnectFreq   time.Duration
+	MaxLineLen      int // maximum line length, not including tags
+	UseTLS          bool
+	UseSASL         bool
+	EnableCTCP      bool
+	Debug           bool
+	AllowPanic      bool // if set, don't recover() from panics in callbacks
+	AllowTruncation bool // if set, truncate lines exceeding MaxLineLen and send them
 
 	// networking and synchronization
 	stateMutex sync.Mutex     // innermost mutex: don't block while holding this

From 97bbb1c2109bc3bff595cdefdc7eb816042a33a8 Mon Sep 17 00:00:00 2001
From: Shivaram Lingamneni <slingamn@cs.stanford.edu>
Date: Fri, 23 Apr 2021 11:30:37 -0400
Subject: [PATCH 2/2] ircutils: add SanitizeText

---
 ircutils/unicode.go      | 37 +++++++++++++++++++++++++++++++++++++
 ircutils/unicode_test.go | 13 +++++++++++++
 2 files changed, 50 insertions(+)

diff --git a/ircutils/unicode.go b/ircutils/unicode.go
index 14f628e..6e1cf44 100644
--- a/ircutils/unicode.go
+++ b/ircutils/unicode.go
@@ -4,6 +4,8 @@
 package ircutils
 
 import (
+	"strings"
+	"unicode"
 	"unicode/utf8"
 )
 
@@ -23,3 +25,38 @@ func TruncateUTF8Safe(message string, byteLimit int) (result string) {
 	}
 	return message
 }
+
+// Sanitizes human-readable text to make it safe for IRC;
+// assumes UTF-8 and uses the replacement character where
+// applicable.
+func SanitizeText(message string, byteLimit int) (result string) {
+	var buf strings.Builder
+
+	for _, r := range message {
+		if r == '\x00' || r == '\r' {
+			continue
+		} else if r == '\n' {
+			if buf.Len()+2 <= byteLimit {
+				buf.WriteString("  ")
+				continue
+			} else {
+				break
+			}
+		} else if unicode.IsSpace(r) {
+			if buf.Len()+1 <= byteLimit {
+				buf.WriteString(" ")
+			} else {
+				break
+			}
+		} else {
+			rLen := utf8.RuneLen(r)
+			if buf.Len()+rLen <= byteLimit {
+				buf.WriteRune(r)
+			} else {
+				break
+			}
+		}
+	}
+
+	return buf.String()
+}
diff --git a/ircutils/unicode_test.go b/ircutils/unicode_test.go
index 3e0c096..5d6fc76 100644
--- a/ircutils/unicode_test.go
+++ b/ircutils/unicode_test.go
@@ -31,3 +31,16 @@ func TestTruncateUTF8(t *testing.T) {
 	// shouldn't truncate the whole string
 	assertEqual(TruncateUTF8Safe("\xff\xff\xff\xff\xff\xff", 5), "\xff\xff")
 }
+
+func TestSanitize(t *testing.T) {
+	assertEqual(SanitizeText("abc", 10), "abc")
+	assertEqual(SanitizeText("abcdef", 5), "abcde")
+
+	assertEqual(SanitizeText("shivaram\x00shivaram\x00shivarampassphrase", 400), "shivaramshivaramshivarampassphrase")
+
+	assertEqual(SanitizeText("the quick brown fox\xffjumps over the lazy dog", 400), "the quick brown fox\xef\xbf\xbdjumps over the lazy dog")
+
+	// \r ignored, \n is two spaces
+	assertEqual(SanitizeText("the quick brown fox\r\njumps over the lazy dog", 400), "the quick brown fox  jumps over the lazy dog")
+	assertEqual(SanitizeText("the quick brown fox\njumps over the lazy dog", 400), "the quick brown fox  jumps over the lazy dog")
+}