From b2c78ffe5972bacf1d511fab99310fd8e39c1fb5 Mon Sep 17 00:00:00 2001
From: Sadie Powell
Date: Fri, 30 Sep 2022 20:33:49 +0100
Subject: Prevent allowing weird characters within hostnames.

---
 src/modules/m_sethost.cpp | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

(limited to 'src/modules/m_sethost.cpp')

diff --git a/src/modules/m_sethost.cpp b/src/modules/m_sethost.cpp
index 769f51cb5..6f563a0d0 100644
--- a/src/modules/m_sethost.cpp
+++ b/src/modules/m_sethost.cpp
@@ -83,9 +83,15 @@ public:
 		auto tag = ServerInstance->Config->ConfValue("hostname");
 		const std::string hmap = tag->getString("charmap", "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz.-_/0123456789", 1);
 
-		cmd.hostmap.reset();
+		CharState newhostmap;
 		for (const auto& chr : hmap)
-			cmd.hostmap.set(static_cast<unsigned char>(chr));
+		{
+			// A hostname can not contain NUL, LF, CR, or SPACE.
+			if (chr == 0x00 || chr == 0x0A || chr == 0x0D || chr == 0x20)
+				throw ModuleException(this, InspIRCd::Format("<hostname:charmap> can not contain character 0x%02X (%c)", chr, chr));
+			newhostmap.set(static_cast<unsigned char>(chr));
+		}
+		std::swap(newhostmap, cmd.hostmap);
 	}
 };
 
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