jsonrpc: allow send_buf to grow as needed

Reallocate the send buffer if more data is written by the RPC handler
than currently fits in the buffer.

Change-Id: I590dd173b843aba48c768adfafaf87e4b47bcc19
Signed-off-by: Daniel Verkamp <daniel.verkamp@intel.com>
Reviewed-on: https://review.gerrithub.io/399925
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Tested-by: SPDK Automated Test System <sys_sgsw@intel.com>
Reviewed-by: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>

CHANGELOG.md

@@ -7,6 +7,9 @@
 The Rpc configuration file section, which was deprecated in v18.01, has been removed.
 Users should switch to the `-r` command-line parameter instead.
 
+The JSON-RPC server implementation now allows up to 32 megabyte responses, growing as
+needed; previously, the response was limited to 32 kilobytes.
+
 ### NVMe Driver
 
 EXPERIMENTAL: Adds support for WDS and RDS capable CMBs in NVMe controllers. This support is

lib/jsonrpc/jsonrpc_internal.h

@@ -42,7 +42,8 @@
 #include "spdk_internal/log.h"
 
 #define SPDK_JSONRPC_RECV_BUF_SIZE	(32 * 1024)
-#define SPDK_JSONRPC_SEND_BUF_SIZE	(32 * 1024)
+#define SPDK_JSONRPC_SEND_BUF_SIZE_INIT	(32 * 1024)
+#define SPDK_JSONRPC_SEND_BUF_SIZE_MAX	(32 * 1024 * 1024)
 #define SPDK_JSONRPC_ID_MAX_LEN		128
 #define SPDK_JSONRPC_MAX_CONNS		64
 #define SPDK_JSONRPC_MAX_VALUES		1024
@@ -54,9 +55,15 @@ struct spdk_jsonrpc_request {
 	struct spdk_json_val id;
 	uint8_t id_data[SPDK_JSONRPC_ID_MAX_LEN];
 
+	/* Total space allocated for send_buf */
+	size_t send_buf_size;
+
+	/* Number of bytes used in send_buf (<= send_buf_size) */
 	size_t send_len;
+
 	size_t send_offset;
-	uint8_t send_buf[SPDK_JSONRPC_SEND_BUF_SIZE];
+
+	uint8_t *send_buf;
 };
 
 struct spdk_jsonrpc_server_conn {

lib/jsonrpc/jsonrpc_server.c

@@ -144,6 +144,13 @@ spdk_jsonrpc_parse_request(struct spdk_jsonrpc_server_conn *conn, void *json, si
 	request->id.type = SPDK_JSON_VAL_INVALID;
 	request->send_offset = 0;
 	request->send_len = 0;
+	request->send_buf_size = SPDK_JSONRPC_SEND_BUF_SIZE_INIT;
+	request->send_buf = malloc(request->send_buf_size);
+	if (request->send_buf == NULL) {
+		SPDK_ERRLOG("Failed to allocate send_buf (%zu bytes)\n", request->send_buf_size);
+		free(request);
+		return -1;
+	}
 
 	if (rc < 0 || rc > SPDK_JSONRPC_MAX_VALUES) {
 		SPDK_DEBUGLOG(SPDK_LOG_RPC, "JSON parse error\n");
@@ -184,12 +191,32 @@ static int
 spdk_jsonrpc_server_write_cb(void *cb_ctx, const void *data, size_t size)
 {
 	struct spdk_jsonrpc_request *request = cb_ctx;
+	size_t new_size = request->send_buf_size;
 
-	if (SPDK_JSONRPC_SEND_BUF_SIZE - request->send_len < size) {
-		SPDK_ERRLOG("Not enough space in send buf\n");
+	while (new_size - request->send_len < size) {
+		if (new_size >= SPDK_JSONRPC_SEND_BUF_SIZE_MAX) {
+			SPDK_ERRLOG("Send buf exceeded maximum size (%zu)\n",
+				    (size_t)SPDK_JSONRPC_SEND_BUF_SIZE_MAX);
 			return -1;
 		}
 
+		new_size *= 2;
+	}
+
+	if (new_size != request->send_buf_size) {
+		uint8_t *new_buf;
+
+		new_buf = realloc(request->send_buf, new_size);
+		if (new_buf == NULL) {
+			SPDK_ERRLOG("Resizing send_buf failed (current size %zu, new size %zu)\n",
+				    request->send_buf_size, new_size);
+			return -1;
+		}
+
+		request->send_buf = new_buf;
+		request->send_buf_size = new_size;
+	}
+
 	memcpy(request->send_buf + request->send_len, data, size);
 	request->send_len += size;
 
@@ -229,6 +256,7 @@ void
 spdk_jsonrpc_free_request(struct spdk_jsonrpc_request *request)
 {
 	request->conn->outstanding_requests--;
+	free(request->send_buf);
 	free(request);
 }
 

test/unit/lib/jsonrpc/jsonrpc_server.c/jsonrpc_server_ut.c

@@ -61,14 +61,21 @@ static size_t g_num_reqs;
 	memcpy(g_buf, in, sizeof(in) - 1); \
 	g_num_reqs = 0; \
 	g_cur_req = NULL; \
-	CU_ASSERT(spdk_jsonrpc_parse_request(conn, g_buf, sizeof(in) - 1) == sizeof(in) - sizeof(trailing))
+	CU_ASSERT(spdk_jsonrpc_parse_request(conn, g_buf, sizeof(in) - 1) == sizeof(in) - sizeof(trailing)); \
+	if (g_cur_req && g_cur_req->request) { \
+		free(g_cur_req->request->send_buf); \
+		g_cur_req->request->send_buf = NULL; \
+	}
 
 #define PARSE_FAIL(in) \
 	memcpy(g_buf, in, sizeof(in) - 1); \
 	g_num_reqs = 0; \
 	g_cur_req = 0; \
-	CU_ASSERT(spdk_jsonrpc_parse_request(conn, g_buf, sizeof(in) - 1) < 0)
-
+	CU_ASSERT(spdk_jsonrpc_parse_request(conn, g_buf, sizeof(in) - 1) < 0); \
+	if (g_cur_req && g_cur_req->request) { \
+		free(g_cur_req->request->send_buf); \
+		g_cur_req->request->send_buf = NULL; \
+	}
 
 #define REQ_BEGIN(expected_error) \
 	if (g_cur_req == NULL) { \
@@ -148,6 +155,9 @@ static size_t g_num_reqs;
 	g_params++
 
 #define FREE_REQUEST() \
+	if (g_reqs->request) { \
+		free(g_reqs->request->send_buf); \
+	} \
 	free(g_reqs->request); \
 	g_reqs->request = NULL