Make non blocking I/O work for accept BIOs.

CHANGES

@@ -4,6 +4,13 @@
 
  Changes between 0.9.6 and 0.9.7  [xx XXX 2000]
 
+  *) Fix for non blocking accept BIOs. Added new I/O special reason
+     BIO_RR_ACCEPT to cover this case. Previously use of accept BIOs
+     with non blocking I/O was not possible because no retry code was
+     implemented. Also added new SSL code SSL_WANT_ACCEPT to cover
+     this case.
+     [Steve Henson]
+
   *) Fix for bug in DirectoryString mask setting. Add support for
      X509_NAME_print_ex() in 'req' and X509_print_ex() function
      to allow certificate printing to more controllable, additional

crypto/bio/b_sock.c

@@ -661,6 +661,7 @@ int BIO_accept(int sock, char **addr)
 	ret=accept(sock,(struct sockaddr *)&from,(void *)&len);
 	if (ret == INVALID_SOCKET)
 		{
+		if(BIO_sock_should_retry(ret)) return -2;
 		SYSerr(SYS_F_ACCEPT,get_last_socket_error());
 		BIOerr(BIO_F_BIO_ACCEPT,BIO_R_ACCEPT_ERROR);
 		goto end;

crypto/bio/bio.h

@@ -179,7 +179,7 @@ extern "C" {
 #define BIO_retry_type(a)		((a)->flags & BIO_FLAGS_RWS)
 #define BIO_should_retry(a)		((a)->flags & BIO_FLAGS_SHOULD_RETRY)
 
-/* The next two are used in conjunction with the
+/* The next three are used in conjunction with the
  * BIO_should_io_special() condition.  After this returns true,
  * BIO *BIO_get_retry_BIO(BIO *bio, int *reason); will walk the BIO 
  * stack and return the 'reason' for the special and the offending BIO.
@@ -188,6 +188,8 @@ extern "C" {
 #define BIO_RR_SSL_X509_LOOKUP		0x01
 /* Returned from the connect BIO when a connect would have blocked */
 #define BIO_RR_CONNECT			0x02
+/* Returned from the accept BIO when an accept would have blocked */
+#define BIO_RR_ACCEPT			0x03
 
 /* These are passed by the BIO callback */
 #define BIO_CB_FREE	0x01

crypto/bio/bss_acpt.c

@@ -236,8 +236,20 @@ again:
 			c->state=ACPT_S_OK;
 			goto again;
 			}
+		BIO_clear_retry_flags(b);
+		b->retry_reason=0;
 		i=BIO_accept(c->accept_sock,&(c->addr));
+
+		/* -2 return means we should retry */
+		if(i == -2)
+			{
+			BIO_set_retry_special(b);
+			b->retry_reason=BIO_RR_ACCEPT;
+			return -1;
+			}
+
 		if (i < 0) return(i);
+
 		bio=BIO_new_socket(i,BIO_CLOSE);
 		if (bio == NULL) goto err;
 

doc/crypto/BIO_s_accept.pod

@@ -92,7 +92,7 @@ BIO_do_accept() serves two functions. When it is first
 called, after the accept BIO has been setup, it will attempt
 to create the accept socket and bind an address to it. Second
 and subsequent calls to BIO_do_accept() will await an incoming
-connection.
+connection, or request a retry in non blocking mode.
 
 =head1 NOTES
 
@@ -130,6 +130,13 @@ however because the accept BIO will still accept additional incoming
 connections. This can be resolved by using BIO_pop() (see above)
 and freeing up the accept BIO after the initial connection.
 
+If the underlying accept socket is non blocking and BIO_do_accept() is
+called to await an incoming connection it is possible for
+BIO_should_io_special() with the reason BIO_RR_ACCEPT. If this happens
+then it is an indication that an accept attempt would block: the application
+should take appropriate action to wait until the underlying socket has
+accepted a connection and retry the call.
+
 =head1 RETURN VALUES
 
 TBA

ssl/bio_ssl.c

@@ -206,6 +206,10 @@ static int ssl_read(BIO *b, char *out, int outl)
 		BIO_set_retry_special(b);
 		retry_reason=BIO_RR_SSL_X509_LOOKUP;
 		break;
+	case SSL_ERROR_WANT_ACCEPT:
+		BIO_set_retry_special(b);
+		retry_reason=BIO_RR_ACCEPT;
+		break;
 	case SSL_ERROR_WANT_CONNECT:
 		BIO_set_retry_special(b);
 		retry_reason=BIO_RR_CONNECT;

ssl/ssl.h

@@ -831,6 +831,7 @@ size_t SSL_get_peer_finished(SSL *s, void *buf, size_t count);
 #define SSL_ERROR_SYSCALL		5 /* look at error stack/return value/errno */
 #define SSL_ERROR_ZERO_RETURN		6
 #define SSL_ERROR_WANT_CONNECT		7
+#define SSL_ERROR_WANT_ACCEPT		8
 
 #define SSL_CTRL_NEED_TMP_RSA			1
 #define SSL_CTRL_SET_TMP_RSA			2

ssl/ssl_lib.c

@@ -1543,6 +1543,8 @@ int SSL_get_error(SSL *s,int i)
 			reason=BIO_get_retry_reason(bio);
 			if (reason == BIO_RR_CONNECT)
 				return(SSL_ERROR_WANT_CONNECT);
+			else if (reason == BIO_RR_ACCEPT)
+				return(SSL_ERROR_WANT_ACCEPT);
 			else
 				return(SSL_ERROR_SYSCALL); /* unknown */
 			}
@@ -1561,6 +1563,8 @@ int SSL_get_error(SSL *s,int i)
 			reason=BIO_get_retry_reason(bio);
 			if (reason == BIO_RR_CONNECT)
 				return(SSL_ERROR_WANT_CONNECT);
+			else if (reason == BIO_RR_ACCEPT)
+				return(SSL_ERROR_WANT_ACCEPT);
 			else
 				return(SSL_ERROR_SYSCALL);
 			}