From e6ccbab5d42b110ac4f6ce1f72cb1e9ccbe4400a Mon Sep 17 00:00:00 2001
From: Li xin <lixin.fnst@cn.fujitsu.com>
Date: Tue, 16 Jun 2015 19:02:38 +0900
Subject: [PATCH] mod_cgi buffers data without bound so fix it

Upstream-Status: Submitted [http://redmine.lighttpd.net/issues/1264]

Signed-off-by: Li Xin <lixin.fnst@cn.fujitsu.com>

Update context for 1.4.36.

Signed-off-by: Kai Kang <kai.kang@windriver.com>
---
 doc/config/lighttpd.conf |   8 ++
 src/mod_cgi.c            | 188 ++++++++++++++++++++++++++++++++++++++++++++---
 2 files changed, 187 insertions(+), 9 deletions(-)

diff --git a/doc/config/lighttpd.conf b/doc/config/lighttpd.conf
index 60b0ae1..9c101a7 100644
--- a/doc/config/lighttpd.conf
+++ b/doc/config/lighttpd.conf
@@ -375,6 +375,14 @@ server.upload-dirs = ( "/var/tmp" )
 ##
 #######################################################################
 
+#######################################################################
+##
+##
+## maximum bytes in send_raw before backing off [KByte]
+##  cgi.high-waterlevel        = 10240
+## minimum bytes in send_raw to disable backoff [KByte]
+##  cgi.low-waterlevel         = 5120
+#######################################################################
 
 #######################################################################
 ##
diff --git a/src/mod_cgi.c b/src/mod_cgi.c
index 01b1877..7c67eb5 100644
--- a/src/mod_cgi.c
+++ b/src/mod_cgi.c
@@ -38,6 +38,10 @@
 
 #include "version.h"
 
+/* for output logs */
+char msgbuf[2048];
+
+
 enum {EOL_UNSET, EOL_N, EOL_RN};
 
 typedef struct {
@@ -53,9 +57,19 @@ typedef struct {
 	size_t size;
 } buffer_pid_t;
 
+struct handler_ctx;
+
+typedef struct {
+	struct handler_ctx **hctx;
+	size_t used;
+	size_t size;
+} buffer_ctx_t;
+
 typedef struct {
 	array *cgi;
 	unsigned short execute_x_only;
+	unsigned int high_waterlevel; /* maximum bytes in send_raw before backing off */
+	unsigned int low_waterlevel;  /* minimum bytes in send_raw to disable backoff */
 } plugin_config;
 
 typedef struct {
@@ -68,9 +82,11 @@ typedef struct {
 	plugin_config **config_storage;
 
 	plugin_config conf;
+
+	buffer_ctx_t cgi_ctx;
 } plugin_data;
 
-typedef struct {
+typedef struct handler_ctx {
 	pid_t pid;
 	int fd;
 	int fde_ndx; /* index into the fd-event buffer */
@@ -78,11 +94,16 @@ typedef struct {
 	connection *remote_conn;  /* dumb pointer */
 	plugin_data *plugin_data; /* dumb pointer */
 
+	int throttling;        /* 1=waiting for send_raw buffer to drain */
+	off_t high_waterlevel; /* maximum bytes in send_raw before backing off */
+	off_t low_waterlevel;  /* minimum bytes in send_raw to disable backoff */
+	off_t bytes_in_buffer;
+
 	buffer *response;
 	buffer *response_header;
 } handler_ctx;
 
-static handler_ctx * cgi_handler_ctx_init(void) {
+static handler_ctx * cgi_handler_ctx_init(plugin_data *p) {
 	handler_ctx *hctx = calloc(1, sizeof(*hctx));
 
 	force_assert(hctx);
@@ -90,13 +111,26 @@ static handler_ctx * cgi_handler_ctx_init(void) {
 	hctx->response = buffer_init();
 	hctx->response_header = buffer_init();
 
+	hctx->throttling = 0;
+	hctx->high_waterlevel = (off_t)p->conf.high_waterlevel * 1024;
+	hctx->low_waterlevel  = (off_t)p->conf.low_waterlevel  * 1024;
+	if (hctx->low_waterlevel >= hctx->high_waterlevel) {
+	    hctx->low_waterlevel = hctx->high_waterlevel * 3 / 4; /* 75% */
+	}
+	hctx->bytes_in_buffer = 0;
+
 	return hctx;
 }
 
-static void cgi_handler_ctx_free(handler_ctx *hctx) {
+static void cgi_handler_ctx_free(server *srv, handler_ctx *hctx) {
 	buffer_free(hctx->response);
 	buffer_free(hctx->response_header);
 
+	/* to avoid confusion */
+	if (hctx->throttling) {
+	    log_error_write(srv, __FILE__, __LINE__, "s", "unthrottled");
+	}
+
 	free(hctx);
 }
 
@@ -154,6 +188,8 @@ SETDEFAULTS_FUNC(mod_fastcgi_set_defaults) {
 	config_values_t cv[] = {
 		{ "cgi.assign",                  NULL, T_CONFIG_ARRAY, T_CONFIG_SCOPE_CONNECTION },       /* 0 */
 		{ "cgi.execute-x-only",          NULL, T_CONFIG_BOOLEAN, T_CONFIG_SCOPE_CONNECTION },     /* 1 */
+		{ "cgi.high-waterlevel",         NULL, T_CONFIG_INT,   T_CONFIG_SCOPE_CONNECTION },       /* 2 */
+		{ "cgi.low-waterlevel",          NULL, T_CONFIG_INT,   T_CONFIG_SCOPE_CONNECTION },       /* 3 */
 		{ NULL,                          NULL, T_CONFIG_UNSET, T_CONFIG_SCOPE_UNSET}
 	};
 
@@ -169,9 +205,13 @@ SETDEFAULTS_FUNC(mod_fastcgi_set_defaults) {
 
 		s->cgi    = array_init();
 		s->execute_x_only = 0;
+		s->high_waterlevel = 0; /* 0 == disabled */
+		s->low_waterlevel  = 0;
 
 		cv[0].destination = s->cgi;
 		cv[1].destination = &(s->execute_x_only);
+		cv[2].destination = &(s->high_waterlevel);
+		cv[3].destination = &(s->low_waterlevel);
 
 		p->config_storage[i] = s;
 
@@ -184,6 +224,51 @@ SETDEFAULTS_FUNC(mod_fastcgi_set_defaults) {
 }
 
 
+static void cgi_recount_bytes_in_buffer(handler_ctx *hctx)
+{
+	chunkqueue *cq = hctx->remote_conn->write_queue;
+	hctx->bytes_in_buffer = chunkqueue_length(cq) - chunkqueue_written(cq);
+}
+
+
+static void cgi_throttling_control(server *srv, handler_ctx *hctx)
+{
+	cgi_recount_bytes_in_buffer(hctx);
+
+#ifdef DEBUG
+	sprintf(msgbuf, "throttling=%d, chars=%llu, high=%llu, low=%llu",
+		hctx->throttling, hctx->bytes_in_buffer,
+		hctx->high_waterlevel, hctx->low_waterlevel);
+	log_error_write(srv, __FILE__, __LINE__, "ss",
+			"(debug) throttling control,", msgbuf);
+#endif
+
+	if (hctx->throttling) {
+		sprintf(msgbuf, "throttling; chars in queue=%llu,"
+			" low-waterlevel=%llu, high-waterlevel=%llu",
+			hctx->bytes_in_buffer,
+			hctx->low_waterlevel, hctx->high_waterlevel);
+		log_error_write(srv, __FILE__, __LINE__, "s", msgbuf);
+		if (hctx->bytes_in_buffer <= hctx->low_waterlevel) {
+			fdevent_event_set(srv->ev, &(hctx->fde_ndx), hctx->fd, FDEVENT_IN);
+			hctx->throttling = 0;
+			log_error_write(srv, __FILE__, __LINE__, "s", "unthrottled");
+		}
+	} else {
+		if (hctx->high_waterlevel != 0 &&
+			hctx->high_waterlevel <= hctx->bytes_in_buffer) {
+			fdevent_event_del(srv->ev, &(hctx->fde_ndx), hctx->fd);
+			hctx->throttling = 1;
+			sprintf(msgbuf, "throttled; chars in queue=%llu,"
+				" low-waterlevel=%llu, high-waterlevel=%llu",
+				hctx->bytes_in_buffer,
+				hctx->low_waterlevel, hctx->high_waterlevel);
+			log_error_write(srv, __FILE__, __LINE__, "s", msgbuf);
+		}
+	}
+}
+
+
 static int cgi_pid_add(server *srv, plugin_data *p, pid_t pid) {
 	int m = -1;
 	size_t i;
@@ -230,6 +315,39 @@ static int cgi_pid_del(server *srv, plugin_data *p, pid_t pid) {
 	return 0;
 }
 
+
+static void cgi_ctx_add(plugin_data *p, handler_ctx *hctx) {
+	buffer_ctx_t *r = &(p->cgi_ctx);
+
+	if (r->size == 0) {
+		r->size = 16;
+		r->hctx = malloc(sizeof(*r->hctx) * r->size);
+	} else if (r->used == r->size) {
+		r->size += 16;
+		r->hctx = realloc(r->hctx, sizeof(*r->hctx) * r->size);
+	}
+
+	r->hctx[r->used++] = hctx;
+}
+
+static void cgi_ctx_del(plugin_data *p, handler_ctx *hctx) {
+	size_t i;
+	buffer_ctx_t *r = &(p->cgi_ctx);
+
+	for (i = 0; i < r->used; i++) {
+		if (r->hctx[i] == hctx) break;
+	}
+
+	if (i != r->used) {
+		/* found */
+
+		if (i != r->used - 1) {
+			r->hctx[i] = r->hctx[r->used - 1];
+		}
+		r->used--;
+	}
+}
+
 static int cgi_response_parse(server *srv, connection *con, plugin_data *p, buffer *in) {
 	char *ns;
 	const char *s;
@@ -380,6 +498,14 @@ static int cgi_demux_response(server *srv, handler_ctx *hctx) {
 
 		buffer_commit(hctx->response, n);
 
+#ifdef DEBUG
+		sprintf(msgbuf, "n=%d, bytes_out=%llu, bytes_in=%llu", n,
+			(unsigned long long)con->write_queue->bytes_out,
+			(unsigned long long)con->write_queue->bytes_in);
+		log_error_write(srv, __FILE__, __LINE__, "ss",
+				"(debug) read,", msgbuf);
+#endif
+
 		/* split header from body */
 
 		if (con->file_started == 0) {
@@ -503,7 +629,20 @@ static int cgi_demux_response(server *srv, handler_ctx *hctx) {
 			}
 		} else {
 			http_chunk_append_buffer(srv, con, hctx->response);
+#ifdef DEBUG
+			sprintf(msgbuf, "n=%d, bytes_out=%llu, bytes_in=%llu, limit=%llu", n,
+				(unsigned long long)con->write_queue->bytes_out,
+				(unsigned long long)con->write_queue->bytes_in,
+				(unsigned long long)hctx->high_waterlevel);
+			log_error_write(srv, __FILE__, __LINE__,
+					"ss", "(debug) append,", msgbuf);
+#endif
 			joblist_append(srv, con);
+
+			cgi_throttling_control(srv, hctx);
+			if (hctx->throttling) {
+				return FDEVENT_HANDLED_NOT_FINISHED;
+			}
 		}
 
 #if 0
@@ -553,8 +692,9 @@ static handler_t cgi_connection_close(server *srv, handler_ctx *hctx) {
 	con->plugin_ctx[p->id] = NULL;
 
 	/* is this a good idea ? */
-	cgi_handler_ctx_free(hctx);
-
+	cgi_ctx_del(p, hctx);
+	cgi_handler_ctx_free(srv, hctx);
+	
 	/* if waitpid hasn't been called by response.c yet, do it here */
 	if (pid) {
 		/* check if the CGI-script is already gone */
@@ -1105,7 +1245,8 @@ static int cgi_create_env(server *srv, connection *con, plugin_data *p, buffer *
 		con->mode = p->id;
 		buffer_reset(con->physical.path);
 
-		hctx = cgi_handler_ctx_init();
+		hctx = cgi_handler_ctx_init(p);
+		cgi_ctx_add(p, hctx);
 
 		hctx->remote_conn = con;
 		hctx->plugin_data = p;
@@ -1114,6 +1255,11 @@ static int cgi_create_env(server *srv, connection *con, plugin_data *p, buffer *
 		hctx->fde_ndx = -1;
 
 		con->plugin_ctx[p->id] = hctx;
+#ifdef DEBUG
+		sprintf(msgbuf, "hctx=%p, con=%p", (void*)hctx, (void*)con);
+		log_error_write(srv, __FILE__, __LINE__, "ss",
+				"(debug) hctx generated, ", msgbuf);
+#endif
 
 		fdevent_register(srv->ev, hctx->fd, cgi_handle_fdevent, hctx);
 		fdevent_event_set(srv->ev, &(hctx->fde_ndx), hctx->fd, FDEVENT_IN);
@@ -1128,7 +1274,8 @@ static int cgi_create_env(server *srv, connection *con, plugin_data *p, buffer *
 
 			close(hctx->fd);
 
-			cgi_handler_ctx_free(hctx);
+			cgi_ctx_del(p, hctx);
+			cgi_handler_ctx_free(srv, hctx);
 
 			con->plugin_ctx[p->id] = NULL;
 
@@ -1153,6 +1300,8 @@ static int mod_cgi_patch_connection(server *srv, connection *con, plugin_data *p
 
 	PATCH(cgi);
 	PATCH(execute_x_only);
+	PATCH(high_waterlevel);
+	PATCH(low_waterlevel);
 
 	/* skip the first, the global context */
 	for (i = 1; i < srv->config_context->used; i++) {
@@ -1170,6 +1319,10 @@ static int mod_cgi_patch_connection(server *srv, connection *con, plugin_data *p
 				PATCH(cgi);
 			} else if (buffer_is_equal_string(du->key, CONST_STR_LEN("cgi.execute-x-only"))) {
 				PATCH(execute_x_only);
+			} else if (buffer_is_equal_string(du->key, CONST_STR_LEN("cgi.high-waterlevel"))) {
+				PATCH(high_waterlevel);
+			} else if (buffer_is_equal_string(du->key, CONST_STR_LEN("cgi.low-waterlevel"))) {
+				PATCH(low_waterlevel);
 			}
 		}
 	}
@@ -1222,6 +1375,21 @@ URIHANDLER_FUNC(cgi_is_handled) {
 TRIGGER_FUNC(cgi_trigger) {
 	plugin_data *p = p_d;
 	size_t ndx;
+
+	for (ndx = 0; ndx < p->cgi_ctx.used; ndx++) {
+		handler_ctx *hctx = p->cgi_ctx.hctx[ndx];
+#ifdef DEBUG
+		connection *con = hctx->remote_conn;
+	
+		sprintf(msgbuf, "hctx=%p, con=%p, bytes_in_buffer=%llu",
+			(void*)hctx, (void*)con,
+			(unsigned long long)hctx->bytes_in_buffer);
+		log_error_write(srv, __FILE__, __LINE__, "ss",
+				"(debug) found using ctx,", msgbuf);
+#endif
+		cgi_throttling_control(srv, hctx);
+	}
+
 	/* the trigger handle only cares about lonely PID which we have to wait for */
 #ifndef __WIN32
 
@@ -1330,7 +1498,8 @@ SUBREQUEST_FUNC(mod_cgi_handle_subrequest) {
 			log_error_write(srv, __FILE__, __LINE__, "sds", "cgi close failed ", hctx->fd, strerror(errno));
 		}
 
-		cgi_handler_ctx_free(hctx);
+		cgi_ctx_del(p, hctx);
+		cgi_handler_ctx_free(srv, hctx);
 
 		con->plugin_ctx[p->id] = NULL;
 
@@ -1362,7 +1531,8 @@ SUBREQUEST_FUNC(mod_cgi_handle_subrequest) {
 			log_error_write(srv, __FILE__, __LINE__, "sds", "cgi close failed ", hctx->fd, strerror(errno));
 		}
 
-		cgi_handler_ctx_free(hctx);
+		cgi_ctx_del(p, hctx);
+		cgi_handler_ctx_free(srv, hctx);
 
 		con->plugin_ctx[p->id] = NULL;
 		return HANDLER_FINISHED;