WIP: Allow http upgrades w/o using connect method.

etc/tinyproxy.conf.in

@@ -235,6 +235,14 @@ Allow 127.0.0.1
 #
 #AddHeader "X-My-Header" "Powered by Tinyproxy"
 
+#
+# AllowUpgrade: 'Upgrade' and 'Connection' headers are stripped in
+# non-HTTPS connections per proxy operation in the HTTP RFC. Enabling
+# fixes unencrypted WebSocket connections but is RFC 2616 non-compliant.
+# May cause issues with in-connection upgrades to unencrypted HTTP/2.
+# Don't enable unless you know what you are doing.
+# AllowUpgrade Yes
+
 #
 # ViaProxyName: The "Via" header is required by the HTTP RFC, but using
 # the real host name is a security concern.  If the following directive

src/conf.c

@@ -126,6 +126,7 @@ static HANDLE_FUNC (handle_defaulterrorfile);
 static HANDLE_FUNC (handle_deny);
 static HANDLE_FUNC (handle_errorfile);
 static HANDLE_FUNC (handle_addheader);
+static HANDLE_FUNC (handle_allowupgrade);
 #ifdef FILTER_ENABLE
 static HANDLE_FUNC (handle_filter);
 static HANDLE_FUNC (handle_filtercasesensitive);
@@ -235,6 +236,7 @@ struct {
         STDCONF ("basicauth", ALNUM WS ALNUM, handle_basicauth),
         STDCONF ("errorfile", INT WS STR, handle_errorfile),
         STDCONF ("addheader",  STR WS STR, handle_addheader),
+        STDCONF ("allowupgrade", BOOL, handle_allowupgrade),
 
 #ifdef FILTER_ENABLE
         /* filtering */
@@ -952,6 +954,12 @@ static HANDLE_FUNC (handle_addheader)
         return 0;
 }
 
+static HANDLE_FUNC (handle_allowupgrade)
+{
+        return set_bool_arg (&conf->allowupgrade, line, &match[2]);
+}
+
+
 /*
  * Log level's strings.
 

src/conf.h

@@ -111,6 +111,14 @@ struct config_s {
          * Extra headers to be added to outgoing HTTP requests.
          */
         vector_t add_headers;
+
+        /*
+         * Allow Upgrade and Connection headers to pass through proxy.
+         * Enables unencrypted WebSocket connections violates RFC
+         * requirements of not passing Connection/Upgrade through a
+         * proxy.  Unexpected behavior may result.
+         */
+        unsigned int allowupgrade;      /* boolean */
 };
 
 extern int reload_config_file (const char *config_fname, struct config_s *conf,

src/reqs.c

@@ -82,6 +82,30 @@
 #define CHECK_LWS(header, len)                                  \
   ((len) > 0 && (header[0] == ' ' || header[0] == '\t'))
 
+static const char *skip_headers_allow_upgrade[] = {
+         "host",
+         "keep-alive",
+         "proxy-connection",
+         "te",
+         "trailers"
+};
+static const char *skip_headers_default[] = {
+         "host",
+         "keep-alive",
+         "proxy-connection",
+         "te",
+         "trailers",
+         "upgrade"
+};
+
+static const char *connection_headers_allow_upgrade[] = {
+        "proxy-connection"
+};
+static const char *connection_headers_default[] = {
+        "connection",
+        "proxy-connection"
+};
+
 /*
  * Read in the first line from the client (the request line for HTTP
  * connections. The request line is allocated from the heap, but it must
@@ -281,6 +305,13 @@ establish_http_connection (struct conn_s *connptr, struct request_s *request)
                                       request->method, request->path,
                                       request->host, portbuff,
                                       connptr->upstream_proxy->ua.authstr);
+        } else if (config.allowupgrade) {
+                /* Allow websockets to not be closed after handshake. */
+                return write_message (connptr->server_fd,
+                                      "%s %s HTTP/1.0\r\n"
+                                      "Host: %s%s\r\n"
+                                      request->method, request->path,
+                                      request->host, portbuff);
         } else {
                 return write_message (connptr->server_fd,
                                       "%s %s HTTP/1.0\r\n"
@@ -721,16 +752,18 @@ static int get_all_headers (int fd, hashmap_t hashofheaders)
  */
 static int remove_connection_headers (hashmap_t hashofheaders)
 {
-        static const char *headers[] = {
+        char **headers;
-                "connection",
-                "proxy-connection"
-        };
-
         char *data;
         char *ptr;
         ssize_t len;
         int i;
 
+        headers = connection_headers_default;
+
+        if (config.allowupgrade) {
+                headers = connection_headers_allow_upgrade;
+        }
+
         for (i = 0; i != (sizeof (headers) / sizeof (char *)); ++i) {
                 /* Look for the connection header.  If it's not found, return. */
                 len =
@@ -850,20 +883,19 @@ done:
 static int
 process_client_headers (struct conn_s *connptr, hashmap_t hashofheaders)
 {
-        static const char *skipheaders[] = {
+        char **skipheaders;
-                "host",
-                "keep-alive",
-                "proxy-connection",
-                "te",
-                "trailers",
-                "upgrade"
-        };
         int i;
         hashmap_iter iter;
         int ret = 0;
 
         char *data, *header;
 
+        skipheaders = skip_headers_default;
+
+        if (config.allowupgrade) {
+                skipheaders = skip_headers_allow_upgrade;
+        }
+
         /*
          * Don't send headers if there's already an error, if the request was
          * a stats request, or if this was a CONNECT method (unless upstream