Server-side support for VMEM packet payload size != 192

Author: troelsjessen

include/vmem/vmem_server.h

@@ -56,6 +56,7 @@ typedef struct {
 		struct {
 			uint64_t address;
 			uint64_t length;
+			uint16_t mtu;
 		} data3;
 		struct {
 			uint8_t vmem_id;

src/vmem/vmem_client.c

@@ -46,7 +46,11 @@ int vmem_download_progress(int node, int timeout, uint64_t address, uint32_t len
 	vmem_request_t * request = (void *) packet->data;
 	request->version = version;
 	request->type = VMEM_SERVER_DOWNLOAD;
-	if (version == 2) {
+	if (version == 3) {
+		request->data3.address = htobe64(address);
+		request->data3.length = htobe64(length);
+		request->data3.mtu = htobe16(VMEM_SERVER_MTU);
+	} else if (version == 2) {
 		request->data2.address = htobe64(address);
 		request->data2.length = htobe32(length);
 	} else {

src/vmem/vmem_server.c

@@ -89,10 +89,18 @@ void vmem_server_handler(csp_conn_t * conn)
 
 		uint64_t length;
 		uint64_t address;
+		uint16_t mtu = VMEM_SERVER_MTU;
+		const uint16_t mtu_max = CSP_BUFFER_SIZE - sizeof(csp_crc32_t) - 5; /* 5 bytes for RDP header */
 
 		if (request->version == 3) {
 			address = be64toh(request->data3.address);
 			length = be64toh(request->data3.length);
+			if (packet->length > offsetof(vmem_request_t, data3.mtu)) {
+				mtu = be16toh(request->data3.mtu);
+				if (mtu == 0 || mtu > CSP_BUFFER_SIZE) {
+					mtu = CSP_BUFFER_SIZE;
+				}
+			}
 		} else if (request->version == 2) {
 			address = be64toh(request->data2.address);
 			length = be32toh(request->data2.length);
@@ -101,6 +109,10 @@ void vmem_server_handler(csp_conn_t * conn)
 			length = be32toh(request->data.length);
 		}
 
+		if (mtu > mtu_max) {
+			mtu = mtu_max;
+		}
+
 		//printf("Download from:");
 		//printf("  Addr %"PRIx64"\n", address);
 		//printf("  Length %"PRIu32"\n", length);
@@ -114,11 +126,11 @@ void vmem_server_handler(csp_conn_t * conn)
 
 			while((count < length) && csp_conn_is_active(conn)) {
 				/* Prepare packet */
-				csp_packet_t * packet = csp_buffer_get(VMEM_SERVER_MTU);
+				csp_packet_t * packet = csp_buffer_get(mtu);
 				if (packet == NULL) {
 					break;
 				}
-				packet->length = VMEM_MIN(VMEM_SERVER_MTU, length - count);
+				packet->length = VMEM_MIN(mtu, length - count);
 
 				/* Get data */
 				vmem_read(packet->data, address + count, packet->length);
@@ -131,7 +143,7 @@ void vmem_server_handler(csp_conn_t * conn)
 		} else if (type == VMEM_SERVER_CALCULATE_CRC32) {
 
 			/* Do the CRC32 calculation on the address area (vmem) using the request packet as the buffer */
-			uint32_t crc = vmem_calc_crc32(address, length, &packet->data[0], VMEM_SERVER_MTU);
+			uint32_t crc = vmem_calc_crc32(address, length, &packet->data[0], mtu);
 
 			/* Convert to network byte order */
 			crc = htobe32(crc);