From 4a9d9b5cc41613c6f43d39f8c05abb5382ea0a98 Mon Sep 17 00:00:00 2001
From: Fabian Keil <fk@fabiankeil.de>
Date: Thu, 11 Sep 2025 14:13:57 +0200
Subject: [PATCH] client_host(): Properly handle IPv6 addresses

Reported by: Joshua Rogers
---
 parsers.c | 31 ++++++++++++++++++++++++++++++-
 1 file changed, 30 insertions(+), 1 deletion(-)

diff --git a/parsers.c b/parsers.c
index 80297813..b08c381d 100644
--- a/parsers.c
+++ b/parsers.c
@@ -3763,7 +3763,36 @@ static jb_err client_host(struct client_state *csp, char **header)
       csp->http->hostport = p;
       freez(csp->http->host);
       csp->http->host = q;
-      q = strchr(csp->http->host, ':');
+
+      if (*p == '[')
+      {
+         /* Numeric IPv6 address delimited by brackets */
+         p++;
+
+         q = strchr(p, ']');
+         if (q == NULL)
+         {
+            /* Missing closing bracket */
+            return JB_ERR_PARSE;
+         }
+
+         *q++ = '\0';
+
+         if (*q == '\0')
+         {
+            q = NULL;
+         }
+         else if (*q != ':')
+         {
+            /* Garbage after closing bracket */
+            return JB_ERR_PARSE;
+         }
+      }
+      else
+      {
+         /* Plain non-escaped hostname */
+         q = strchr(csp->http->host, ':');
+      }
       if (q != NULL)
       {
          /* Terminate hostname and evaluate port string */
-- 
2.50.1