new control code BIO_C_RESET_READ_REQUEST

crypto/bio/bio.h

@@ -334,6 +334,7 @@ typedef struct bio_f_buffer_ctx_struct
 #define BIO_C_NREAD				144
 #define BIO_C_NWRITE0				145
 #define BIO_C_NWRITE				146
+#define BIO_C_RESET_READ_REQUEST		147
 
 
 #define BIO_set_app_data(s,arg)		BIO_set_ex_data(s,0,(char *)arg)
@@ -470,6 +471,7 @@ size_t BIO_ctrl_wpending(BIO *b);
 #define BIO_get_read_request(b)    (int)BIO_ctrl(b,BIO_C_GET_READ_REQUEST,0,NULL)
 size_t BIO_ctrl_get_write_guarantee(BIO *b);
 size_t BIO_ctrl_get_read_request(BIO *b);
+int BIO_ctrl_reset_read_request(BIO *b);
 
 #ifdef NO_STDIO
 #define NO_FP_API

crypto/bio/bss_bio.c

@@ -493,6 +493,15 @@ static long bio_ctrl(BIO *bio, int cmd, long num, void *ptr)
 		ret = (long) b->request;
 		break;
 
+	case BIO_C_RESET_READ_REQUEST:
+		/* Reset request.  (Can be useful after read attempts
+		 * at the other side that are meant to be non-blocking,
+		 * e.g. when probing SSL_read to see if any data is
+		 * available.) */
+		b->request = 0;
+		ret = 1;
+		break;
+
 	case BIO_C_SHUTDOWN_WR:
 		/* similar to shutdown(..., SHUT_WR) */
 		b->closed = 1;
@@ -750,6 +759,11 @@ size_t BIO_ctrl_get_read_request(BIO *bio)
 	return BIO_ctrl(bio, BIO_C_GET_READ_REQUEST, 0, NULL);
 	}
 
+int BIO_ctrl_reset_read_request(BIO *bio)
+	{
+	return (BIO_ctrl(bio, BIO_C_RESET_READ_REQUEST, 0, NULL) != 0);
+	}
+
 
 /* BIO_nread0/nread/nwrite0/nwrite are availabe only for BIO pairs for now
  * (conceivably some other BIOs could allow non-copying reads and writes too.)