[multiple] reset http vers, avoid rare crash (fixes #3152)

(thx ultimator)

do not set r->http_version to HTTP_VERSION_2 when selecting TLS ALPN
if r->handler_module already set, since handler module is likely
mod_sockproxy, and con->h2 will not get initialized.

This does continue to select "h2", so the mod_sockproxy backend
should be prepared to receive the HTTP/2 client connection preface.

x-ref:
  "Random Segfaults with version 1.4.64 w/ mod_sockproxy and ALPN h2"
  https://redmine.lighttpd.net/issues/3152

src/mod_gnutls.c

@@ -1406,7 +1406,8 @@ mod_gnutls_ALPN (handler_ctx * const hctx, const unsigned char * const in, const
             if (in[i] == 'h' && in[i+1] == '2') {
                 if (!hctx->r->conf.h2proto) continue;
                 hctx->alpn = MOD_GNUTLS_ALPN_H2;
-                hctx->r->http_version = HTTP_VERSION_2;
+                if (hctx->r->handler_module == NULL)/*(e.g. not mod_sockproxy)*/
+                    hctx->r->http_version = HTTP_VERSION_2;
                 return GNUTLS_E_SUCCESS;
             }
             continue;

src/mod_mbedtls.c

@@ -1202,7 +1202,8 @@ mod_mbedtls_alpn_selected (handler_ctx * const hctx, const char * const in)
       case 2:  /* "h2" */
         if (in[i] == 'h' && in[i+1] == '2') {
             proto = MOD_MBEDTLS_ALPN_H2;
-            hctx->r->http_version = HTTP_VERSION_2;
+            if (hctx->r->handler_module == NULL)/*(e.g. not mod_sockproxy)*/
+                hctx->r->http_version = HTTP_VERSION_2;
             break;
         }
         return 0;
@@ -1247,7 +1248,8 @@ mod_mbedtls_alpn_select_cb (handler_ctx *hctx, const unsigned char *in, const un
             if (in[i] == 'h' && in[i+1] == '2') {
                 if (!hctx->r->conf.h2proto) continue;
                 hctx->alpn = MOD_MBEDTLS_ALPN_H2;
-                hctx->r->http_version = HTTP_VERSION_2;
+                if (hctx->r->handler_module == NULL)/*(e.g. not mod_sockproxy)*/
+                    hctx->r->http_version = HTTP_VERSION_2;
                 return 0;
             }
             continue;

src/mod_nss.c

@@ -1367,7 +1367,8 @@ mod_nss_alpn_select_cb (void *arg, PRFileDesc *ssl,
                   case 0:
                     if (!hctx->r->conf.h2proto) continue;
                     hctx->alpn = MOD_NSS_ALPN_H2;
-                    hctx->r->http_version = HTTP_VERSION_2;
+                    if (hctx->r->handler_module == NULL)/*(not mod_sockproxy)*/
+                        hctx->r->http_version = HTTP_VERSION_2;
                     break;
                   case 1:
                     hctx->alpn = MOD_NSS_ALPN_HTTP11;

src/mod_openssl.c

@@ -1883,7 +1883,8 @@ mod_openssl_alpn_select_cb (SSL *ssl, const unsigned char **out, unsigned char *
             if (in[i] == 'h' && in[i+1] == '2') {
                 if (!hctx->r->conf.h2proto) continue;
                 proto = MOD_OPENSSL_ALPN_H2;
-                hctx->r->http_version = HTTP_VERSION_2;
+                if (hctx->r->handler_module == NULL)/*(e.g. not mod_sockproxy)*/
+                    hctx->r->http_version = HTTP_VERSION_2;
                 break;
             }
             continue;

src/mod_wolfssl.c

@@ -1823,7 +1823,8 @@ mod_openssl_alpn_select_cb (SSL *ssl, const unsigned char **out, unsigned char *
             if (in[i] == 'h' && in[i+1] == '2') {
                 if (!hctx->r->conf.h2proto) continue;
                 proto = MOD_OPENSSL_ALPN_H2;
-                hctx->r->http_version = HTTP_VERSION_2;
+                if (hctx->r->handler_module == NULL)/*(e.g. not mod_sockproxy)*/
+                    hctx->r->http_version = HTTP_VERSION_2;
                 break;
             }
             continue;