From b57d794aaf34f1505a6f55670de7594596b5a031 Mon Sep 17 00:00:00 2001
From: Alexey Sokolov <alexey+znc@asokolov.org>
Date: Sun, 8 Jan 2023 15:32:27 +0000
Subject: [PATCH] Send multiline CAP LS response for IRCv3.2 clients

---
 include/znc/Client.h            |  2 ++
 src/Client.cpp                  | 40 ++++++++++++++++++++++++++-----
 test/integration/tests/core.cpp | 42 +++++++++++++++++++++++++++++++++
 3 files changed, 78 insertions(+), 6 deletions(-)

diff --git a/include/znc/Client.h b/include/znc/Client.h
index 5428cf44..af09e4aa 100644
--- a/include/znc/Client.h
+++ b/include/znc/Client.h
@@ -103,6 +103,7 @@ class CClient : public CIRCSocket {
           m_bGotPass(false),
           m_bGotNick(false),
           m_bGotUser(false),
+          m_bCap302(false),
           m_bInCap(false),
           m_bCapNotify(false),
           m_bAwayNotify(false),
@@ -349,6 +350,7 @@ class CClient : public CIRCSocket {
     bool m_bGotPass;
     bool m_bGotNick;
     bool m_bGotUser;
+    bool m_bCap302;
     bool m_bInCap;
     bool m_bCapNotify;
     bool m_bAwayNotify;
diff --git a/src/Client.cpp b/src/Client.cpp
index 6d215218..44ec66be 100644
--- a/src/Client.cpp
+++ b/src/Client.cpp
@@ -687,6 +687,21 @@ void CClient::RespondCap(const CString& sResponse) {
     PutClient(":irc.znc.in CAP " + GetNick() + " " + sResponse);
 }
 
+static VCString MultiLine(const SCString& ssCaps) {
+    VCString vsRes = {""};
+    for (const CString& sCap : ssCaps) {
+        if (vsRes.back().length() + sCap.length() > 400) {
+            vsRes.push_back(sCap);
+        } else {
+            if (!vsRes.back().empty()) {
+                vsRes.back() += " ";
+            }
+            vsRes.back() += sCap;
+        }
+    }
+    return vsRes;
+}
+
 void CClient::HandleCap(const CMessage& Message) {
     CString sSubCmd = Message.GetParam(0);
 
@@ -699,12 +714,18 @@ void CClient::HandleCap(const CMessage& Message) {
                 ssOfferCaps.insert(it.first);
         }
         GLOBALMODULECALL(OnClientCapLs(this, ssOfferCaps), NOTHING);
-        CString sRes =
-            CString(" ").Join(ssOfferCaps.begin(), ssOfferCaps.end());
-        RespondCap("LS :" + sRes);
+        VCString vsCaps = MultiLine(ssOfferCaps);
         m_bInCap = true;
         if (Message.GetParam(1).ToInt() >= 302) {
+            m_bCap302 = true;
             m_bCapNotify = true;
+            for (int i = 0; i < vsCaps.size() - 1; ++i) {
+                RespondCap("LS * :" + vsCaps[i]);
+            }
+            RespondCap("LS :" + vsCaps.back());
+        } else {
+            // Can't send more than one line of caps :(
+            RespondCap("LS :" + vsCaps.front());
         }
     } else if (sSubCmd.Equals("END")) {
         m_bInCap = false;
@@ -763,9 +784,16 @@ void CClient::HandleCap(const CMessage& Message) {
 
         RespondCap("ACK :" + Message.GetParam(1));
     } else if (sSubCmd.Equals("LIST")) {
-        CString sList =
-            CString(" ").Join(m_ssAcceptedCaps.begin(), m_ssAcceptedCaps.end());
-        RespondCap("LIST :" + sList);
+        VCString vsCaps = MultiLine(m_ssAcceptedCaps);
+        if (m_bCap302) {
+            for (int i = 0; i < vsCaps.size() - 1; ++i) {
+                RespondCap("LIST * :" + vsCaps[i]);
+            }
+            RespondCap("LIST :" + vsCaps.back());
+        } else {
+            // Can't send more than one line of caps :(
+            RespondCap("LISTS :" + vsCaps.front());
+        }
     } else {
         PutClient(":irc.znc.in 410 " + GetNick() + " " + sSubCmd +
                   " :Invalid CAP subcommand");
diff --git a/test/integration/tests/core.cpp b/test/integration/tests/core.cpp
index a0c23a4b..8f9618f8 100644
--- a/test/integration/tests/core.cpp
+++ b/test/integration/tests/core.cpp
@@ -165,6 +165,7 @@ TEST_F(ZNCTest, InvalidConfigInChan) {
     auto znc = Run();
     znc->ShouldFinishItself(1);
 }
+
 TEST_F(ZNCTest, Encoding) {
     auto znc = Run();
     auto ircd = ConnectIRCd();
@@ -430,5 +431,46 @@ TEST_F(ZNCTest, DenyOptions) {
     client2.ReadUntil("Access denied!");
 }
 
+TEST_F(ZNCTest, CAP302MultiLS) {
+    auto znc = Run();
+    auto ircd = ConnectIRCd();
+    auto client = LoginClient();
+    InstallModule("testmod.cpp", R"(
+        #include <znc/Client.h>
+        #include <znc/Modules.h>
+        class TestModule : public CModule {
+          public:
+            MODCONSTRUCTOR(TestModule) {}
+            void OnClientCapLs(CClient* pClient, SCString& ssCaps) override {
+                for (int i = 0; i < 100; ++i) {
+                    ssCaps.insert("testcap-" + CString(i));
+                }
+            }
+        };
+        GLOBALMODULEDEFS(TestModule, "Test")
+    )");
+    client.Write("znc loadmod testmod");
+    client.ReadUntil("Loaded module testmod");
+
+    auto client2 = ConnectClient();
+    client2.Write("CAP LS");
+    client2.ReadUntil("LS :");
+    auto rem = client2.ReadRemainder();
+    ASSERT_GT(rem.indexOf("testcap-10"), 10);
+    ASSERT_EQ(rem.indexOf("testcap-80"), -1);
+    ASSERT_EQ(rem.indexOf("LS"), -1);
+
+    client2 = ConnectClient();
+    client2.Write("CAP LS 302");
+    client2.ReadUntil("LS * :");
+    rem = client2.ReadRemainder();
+    qsizetype w = 0;
+    ASSERT_GT(w = rem.indexOf("testcap-10"), 1);
+    ASSERT_GT(w = rem.indexOf("testcap-22", w), 1);
+    ASSERT_GT(w = rem.indexOf("LS * :", w), 1);
+    ASSERT_GT(rem.indexOf("testcap-80", w), 1);
+    ASSERT_GT(rem.indexOf("LS :", w), 1);
+}
+
 }  // namespace
 }  // namespace znc_inttest