Added http method extending

User can define his own response method by calling
evhttp_set_ext_method_cmp() on the struct http, or
evhttp_connection_set_ext_method_cmp() on the connection.

We expose a new stucture `evhttp_ext_method` which is passed to the
callback if it's set. So any field can be modified, with some exceptions
(in evhttp_method_):

If the cmp function is set, it has the ability to modify method, and
flags. Other fields will be ignored. Flags returned are OR'd with the
current flags.

Based on changes to the #282 from: Mark Ellzey <socket@gmail.com>

1 files changed, 93 insertions, 38 deletions

diff --git a/http.c b/http.c
index 00267828..ecb12bbf 100644
--- a/http.c
+++ b/http.c
@@ -192,13 +192,15 @@ static void evhttp_get_request(struct evhttp *, evutil_socket_t, struct sockaddr
 static void evhttp_write_buffer(struct evhttp_connection *,
     void (*)(struct evhttp_connection *, void *), void *);
 static void evhttp_make_header(struct evhttp_connection *, struct evhttp_request *);
+static int evhttp_method_may_have_body_(struct evhttp_connection *, enum evhttp_cmd_type);
 
 /* callbacks for bufferevent */
 static void evhttp_read_cb(struct bufferevent *, void *);
 static void evhttp_write_cb(struct bufferevent *, void *);
 static void evhttp_error_cb(struct bufferevent *bufev, short what, void *arg);
-static int evhttp_find_vhost(struct evhttp *http, struct evhttp **outhttp,
-		  const char *hostname);
+static int evhttp_find_vhost(struct evhttp *http, struct evhttp **outhttp, const char *hostname);
+static const char *evhttp_method_(struct evhttp_connection *evcon,
+	enum evhttp_cmd_type type, ev_uint16_t *flags);
 
 #ifndef EVENT__HAVE_STRSEP
 /* strsep replacement for platforms that lack it.  Only works if
@@ -296,12 +298,15 @@ evhttp_htmlescape(const char *html)
 }
 
 /** Given an evhttp_cmd_type, returns a constant string containing the
- * equivalent HTTP command, or NULL if the evhttp_command_type is
+ * equivalent HTTP command, or NULL if the evhttp_cmd_type is
  * unrecognized. */
 static const char *
-evhttp_method(enum evhttp_cmd_type type)
+evhttp_method_(struct evhttp_connection *evcon,
+              enum evhttp_cmd_type type, ev_uint16_t *flags)
 {
-	const char *method;
+	struct evhttp_ext_method ext_method;
+	const char *method    = NULL;
+	ev_uint16_t tmp_flags = EVHTTP_METHOD_HAS_BODY;
 
 	switch (type) {
 	case EVHTTP_REQ_GET:
@@ -312,6 +317,7 @@ evhttp_method(enum evhttp_cmd_type type)
 		break;
 	case EVHTTP_REQ_HEAD:
 		method = "HEAD";
+		tmp_flags &= ~EVHTTP_METHOD_HAS_BODY;
 		break;
 	case EVHTTP_REQ_PUT:
 		method = "PUT";
@@ -324,6 +330,7 @@ evhttp_method(enum evhttp_cmd_type type)
 		break;
 	case EVHTTP_REQ_TRACE:
 		method = "TRACE";
+		tmp_flags &= ~EVHTTP_METHOD_HAS_BODY;
 		break;
 	case EVHTTP_REQ_CONNECT:
 		method = "CONNECT";
@@ -353,10 +360,41 @@ evhttp_method(enum evhttp_cmd_type type)
 		method = "MOVE";
 		break;
 	default:
-		method = NULL;
+		/* setup the structure to allow for the cmp.
+		 *
+		 * if the cmp function is set, it has the ability to
+		 * modify method and flags. Other fields will be
+		 * ignored.
+		 *
+		 * NOTE: the flags returned are OR'd with the current
+		 *       flags.
+		 */
+		tmp_flags = 0;
+		ext_method.method = NULL;
+		ext_method.type   = type;
+		ext_method.flags  = tmp_flags;
+
+		if (evcon->ext_method_cmp != NULL &&
+			evcon->ext_method_cmp(&ext_method) == 0) {
+
+			if (ext_method.type != type) {
+				event_debug(("%s: callback modified type from %u to %u, not allowed",
+				            __func__, type, ext_method.type));
+				return NULL;
+			}
+
+			method     = ext_method.method;
+			tmp_flags |= ext_method.flags;
+		}
+
 		break;
 	}
 
+	event_debug(("%s: type=%04x => '%s' flags=%04x",
+	             __func__, (int)type, method, tmp_flags));
+
+	if (flags)
+		*flags = tmp_flags;
 	return (method);
 }
 
@@ -452,11 +490,12 @@ evhttp_make_header_request(struct evhttp_connection *evcon,
     struct evhttp_request *req)
 {
 	const char *method;
+	ev_uint16_t flags;
 
 	evhttp_remove_header(req->output_headers, "Proxy-Connection");
 
 	/* Generate request line */
-	if (!(method = evhttp_method(req->type))) {
+	if (!(method = evhttp_method_(evcon, req->type, &flags))) {
 		method = "NULL";
 	}
 
@@ -464,9 +503,12 @@ evhttp_make_header_request(struct evhttp_connection *evcon,
 	    "%s %s HTTP/%d.%d\r\n",
 	    method, req->uri, req->major, req->minor);
 
-	/* Add the content length on a post or put request if missing */
-	if ((req->type == EVHTTP_REQ_POST || req->type == EVHTTP_REQ_PUT) &&
-	    evhttp_find_header(req->output_headers, "Content-Length") == NULL){
+	/* Add the content length on a request if missing
+	 * Always add it for POST and PUT requests as clients expect it */
+	if ((flags & EVHTTP_METHOD_HAS_BODY) &&
+	    (evbuffer_get_length(req->output_buffer) > 0 ||
+	     req->type == EVHTTP_REQ_POST || req->type == EVHTTP_REQ_PUT) &&
+	    evhttp_find_header(req->output_headers, "Content-Length") == NULL) {
 		char size[22];
 		evutil_snprintf(size, sizeof(size), EV_SIZE_FMT,
 		    EV_SIZE_ARG(evbuffer_get_length(req->output_buffer)));
@@ -1941,10 +1983,29 @@ evhttp_parse_request_line(struct evhttp_request *req, char *line, size_t len)
 	} /* switch */
 
 	if (!type) {
+		/* check extended methods, we only care about the
+		 * type set by the cmp function if the cmp function
+		 * returns a 0 value.
+		 */
+		struct evhttp_ext_method ext_method;
+
+		ext_method.method = method;
+		ext_method.type = 0;
+
+		if (req->evcon->ext_method_cmp &&
+		    req->evcon->ext_method_cmp(&ext_method) == 0) {
+			/* TODO: make sure the other fields in ext_method are
+			 * not changed by the callback.
+			 */
+			type = ext_method.type;
+		}
+	}
+
+	if (!type) {
 		event_debug(("%s: bad method %s on request %p from %s",
-			__func__, method, req, req->remote_host));
-		/* No error yet; we'll give a better error later when we see that
-		 * req->type is unsupported in evhttp_handle_request(). */
+		            __func__, method, req, req->remote_host));
+		/* No error yet; we'll give a better error later when
+		 * we see that req->type is unsupported. */
 	}
 
 	req->type = type;
@@ -2278,31 +2339,11 @@ evhttp_get_body_length(struct evhttp_request *req)
 }
 
 static int
-evhttp_method_may_have_body(enum evhttp_cmd_type type)
+evhttp_method_may_have_body_(struct evhttp_connection *evcon, enum evhttp_cmd_type type)
 {
-	switch (type) {
-	case EVHTTP_REQ_POST:
-	case EVHTTP_REQ_PUT:
-	case EVHTTP_REQ_PATCH:
-	case EVHTTP_REQ_PROPFIND:
-	case EVHTTP_REQ_PROPPATCH:
-	case EVHTTP_REQ_MKCOL:
-	case EVHTTP_REQ_LOCK:
-	case EVHTTP_REQ_UNLOCK:
-	case EVHTTP_REQ_COPY:
-	case EVHTTP_REQ_MOVE:
-
-	case EVHTTP_REQ_GET:
-	case EVHTTP_REQ_DELETE:
-	case EVHTTP_REQ_OPTIONS:
-	case EVHTTP_REQ_CONNECT:
-		return 1;
-
-	case EVHTTP_REQ_TRACE:
-	case EVHTTP_REQ_HEAD:
-	default:
-		return 0;
-	}
+	ev_uint16_t flags;
+	evhttp_method_(evcon, type, &flags);
+	return (flags & EVHTTP_METHOD_HAS_BODY) ? 1 : 0;
 }
 
 static void
@@ -2312,7 +2353,7 @@ evhttp_get_body(struct evhttp_connection *evcon, struct evhttp_request *req)
 
 	/* If this is a request without a body, then we are done */
 	if (req->kind == EVHTTP_REQUEST &&
-	    !evhttp_method_may_have_body(req->type)) {
+	    !evhttp_method_may_have_body_(evcon, req->type)) {
 		evhttp_connection_done(evcon);
 		return;
 	}
@@ -2576,6 +2617,13 @@ int evhttp_connection_set_flags(struct evhttp_connection *evcon,
 }
 
 void
+evhttp_connection_set_ext_method_cmp(struct evhttp_connection *evcon,
+	evhttp_ext_method_cb cmp)
+{
+	evcon->ext_method_cmp = cmp;
+}
+
+void
 evhttp_connection_set_base(struct evhttp_connection *evcon,
     struct event_base *base)
 {
@@ -4040,6 +4088,12 @@ evhttp_set_allowed_methods(struct evhttp* http, ev_uint32_t methods)
 	http->allowed_methods = methods;
 }
 
+void
+evhttp_set_ext_method_cmp(struct evhttp *http, evhttp_ext_method_cb cmp)
+{
+	http->ext_method_cmp = cmp;
+}
+
 int
 evhttp_set_cb(struct evhttp *http, const char *uri,
     void (*cb)(struct evhttp_request *, void *), void *cbarg)
@@ -4476,6 +4530,7 @@ evhttp_get_request(struct evhttp *http, evutil_socket_t fd,
 	 * we need to know which http server it belongs to.
 	 */
 	evcon->http_server = http;
+	evcon->ext_method_cmp = http->ext_method_cmp;
 	TAILQ_INSERT_TAIL(&http->connections, evcon, next);
 
 	if (evhttp_associate_new_request_with_connection(evcon) == -1)