From 72bb48954363c4df058fbbef05759d79db82f40d Mon Sep 17 00:00:00 2001
From: Stefan Eissing <stefan@eissing.org>
Date: Fri, 17 Feb 2023 10:17:06 +0100
Subject: [PATCH] setopt: allow HTTP3 when HTTP2 is not defined

Reported-by: Karthikdasari0423 on github
Fixes #10538
Closes #10544
---
 lib/setopt.c | 42 +++++++++++++++++++++++++++++-------------
 1 file changed, 29 insertions(+), 13 deletions(-)

diff --git a/lib/setopt.c b/lib/setopt.c
index b8fa1b89e6..604693ad94 100644
--- a/lib/setopt.c
+++ b/lib/setopt.c
@@ -895,22 +895,38 @@ CURLcode Curl_vsetopt(struct Curl_easy *data, CURLoption option, va_list param)
      * the listed enums in curl/curl.h.
      */
     arg = va_arg(param, long);
-    if(arg < CURL_HTTP_VERSION_NONE)
-      return CURLE_BAD_FUNCTION_ARGUMENT;
+    switch(arg) {
+    case CURL_HTTP_VERSION_NONE:
+#ifdef USE_HTTP2
+      /* TODO: this seems an undesirable quirk to force a behaviour on
+       * lower implementations that they should recognize independantly? */
+      arg = CURL_HTTP_VERSION_2TLS;
+#endif
+      /* accepted */
+      break;
+    case CURL_HTTP_VERSION_1_0:
+    case CURL_HTTP_VERSION_1_1:
+      /* accepted */
+      break;
+#ifdef USE_HTTP2
+    case CURL_HTTP_VERSION_2_0:
+    case CURL_HTTP_VERSION_2TLS:
+    case CURL_HTTP_VERSION_2_PRIOR_KNOWLEDGE:
+      /* accepted */
+      break;
+#endif
 #ifdef ENABLE_QUIC
-    if(arg == CURL_HTTP_VERSION_3)
-      ;
-    else
+    case CURL_HTTP_VERSION_3:
+    case CURL_HTTP_VERSION_3ONLY:
+      /* accepted */
+      break;
 #endif
-#ifndef USE_HTTP2
-    if(arg >= CURL_HTTP_VERSION_2)
-      return CURLE_UNSUPPORTED_PROTOCOL;
-#else
-    if(arg >= CURL_HTTP_VERSION_LAST)
+    default:
+      /* not accepted */
+      if(arg < CURL_HTTP_VERSION_NONE)
+        return CURLE_BAD_FUNCTION_ARGUMENT;
       return CURLE_UNSUPPORTED_PROTOCOL;
-    if(arg == CURL_HTTP_VERSION_NONE)
-      arg = CURL_HTTP_VERSION_2TLS;
-#endif
+    }
     data->set.httpwant = (unsigned char)arg;
     break;
 
-- 
2.47.2