Remove SSL3_FLAGS_POP_BUFFER.

This is an experimental flag that dates back to SSLeay 0.8.1b or earlier. It's
never set internally and never set in consumers.

Change-Id: I922583635c9f3d8d93f08f1707531ad22a26ae6a
Reviewed-on: https://boringssl-review.googlesource.com/2214
Reviewed-by: Adam Langley <agl@google.com>

include/openssl/ssl3.h

@@ -339,7 +339,6 @@ typedef struct ssl3_buffer_st
 
 
 #define SSL3_FLAGS_NO_RENEGOTIATE_CIPHERS	0x0001
-#define SSL3_FLAGS_POP_BUFFER			0x0004
 /* TODO(davidben): This flag can probably be merged into s3->change_cipher_spec
  * to something tri-state. (Normal / Expect CCS / Between CCS and Finished). */
 #define SSL3_FLAGS_EXPECT_CCS			0x0080
@@ -349,7 +348,6 @@ typedef struct ssl3_buffer_st
 typedef struct ssl3_state_st
 	{
 	long flags;
-	int delay_buf_pop_ret;
 
 	unsigned char read_sequence[8];
 	int read_mac_secret_size;

ssl/d1_clnt.c

@@ -439,8 +439,6 @@ int dtls1_connect(SSL *s)
 			if (ret <= 0) goto end;
 			s->state=SSL3_ST_CW_FLUSH;
 
-			/* clear flags */
-			s->s3->flags&= ~SSL3_FLAGS_POP_BUFFER;
 			if (s->hit)
 				{
 				s->s3->tmp.next_state=SSL_ST_OK;
@@ -520,11 +518,8 @@ int dtls1_connect(SSL *s)
 				}
 #endif
 
-			/* If we are not 'joining' the last two packets,
-			 * remove the buffering now */
-			if (!(s->s3->flags & SSL3_FLAGS_POP_BUFFER))
-				ssl_free_wbio_buffer(s);
-			/* else do it later in ssl3_write */
+			/* Remove write buffering now. */
+			ssl_free_wbio_buffer(s);
 
 			s->init_num=0;
 			s->renegotiate=0;

ssl/s3_clnt.c

@@ -467,8 +467,6 @@ int ssl3_connect(SSL *s)
 			if (ret <= 0) goto end;
 			s->state=SSL3_ST_CW_FLUSH;
 
-			/* clear flags */
-			s->s3->flags&= ~SSL3_FLAGS_POP_BUFFER;
 			if (s->hit)
 				{
 				s->s3->tmp.next_state=SSL_ST_OK;
@@ -579,11 +577,8 @@ int ssl3_connect(SSL *s)
 				s->init_buf=NULL;
 				}
 
-			/* If we are not 'joining' the last two packets,
-			 * remove the buffering now */
-			if (!(s->s3->flags & SSL3_FLAGS_POP_BUFFER))
-				ssl_free_wbio_buffer(s);
-			/* else do it later in ssl3_write */
+			/* Remove write buffering now. */
+			ssl_free_wbio_buffer(s);
 
 			s->init_num=0;
 			s->renegotiate=0;

ssl/s3_lib.c

@@ -2037,8 +2037,6 @@ int ssl3_shutdown(SSL *s)
 
 int ssl3_write(SSL *s, const void *buf, int len)
 	{
-	int ret,n;
-
 #if 0
 	if (s->shutdown & SSL_SEND_SHUTDOWN)
 		{
@@ -2049,63 +2047,15 @@ int ssl3_write(SSL *s, const void *buf, int len)
 	ERR_clear_system_error();
 	if (s->s3->renegotiate) ssl3_renegotiate_check(s);
 
-	/* This is an experimental flag that sends the
-	 * last handshake message in the same packet as the first
-	 * use data - used to see if it helps the TCP protocol during
-	 * session-id reuse */
-	/* The second test is because the buffer may have been removed */
-	if ((s->s3->flags & SSL3_FLAGS_POP_BUFFER) && (s->wbio == s->bbio))
-		{
-		/* First time through, we write into the buffer */
-		if (s->s3->delay_buf_pop_ret == 0)
-			{
-			ret=ssl3_write_bytes(s,SSL3_RT_APPLICATION_DATA,
-					     buf,len);
-			if (ret <= 0) return(ret);
-
-			s->s3->delay_buf_pop_ret=ret;
-			}
-
-		s->rwstate=SSL_WRITING;
-		n=BIO_flush(s->wbio);
-		if (n <= 0) return(n);
-		s->rwstate=SSL_NOTHING;
-
-		/* We have flushed the buffer, so remove it */
-		ssl_free_wbio_buffer(s);
-		s->s3->flags&= ~SSL3_FLAGS_POP_BUFFER;
-
-		ret=s->s3->delay_buf_pop_ret;
-		s->s3->delay_buf_pop_ret=0;
-		}
-	else
-		{
-		ret=s->method->ssl_write_bytes(s,SSL3_RT_APPLICATION_DATA,
-			buf,len);
-		if (ret <= 0) return(ret);
-		}
-
-	return(ret);
+	return s->method->ssl_write_bytes(s, SSL3_RT_APPLICATION_DATA, buf,
+		len);
 	}
 
 static int ssl3_read_internal(SSL *s, void *buf, int len, int peek)
 	{
-	int n,ret;
+	int ret;
 	
 	ERR_clear_system_error();
-	if ((s->s3->flags & SSL3_FLAGS_POP_BUFFER) && (s->wbio == s->bbio))
-		{
-		/* Deal with an application that calls SSL_read() when handshake data
-		 * is yet to be written.
-		 */
-		if (BIO_wpending(s->wbio) > 0)
-			{
-			s->rwstate=SSL_WRITING;
-			n=BIO_flush(s->wbio);
-			if (n <= 0) return(n);
-			s->rwstate=SSL_NOTHING;
-			}
-		}
 	if (s->s3->renegotiate) ssl3_renegotiate_check(s);
 	s->s3->in_read_app_data=1;
 	ret=s->method->ssl_read_bytes(s,SSL3_RT_APPLICATION_DATA,buf,len,peek);