Make SSL_read and SSL_write return the old behaviour and document it.

This reverts commit 4880672a.

Fixes: #1903
Reviewed-by: NMatt Caswell <matt@openssl.org>

GH: #1931

doc/man3/SSL_get_error.pod

@@ -38,12 +38,12 @@ if and only if B<ret E<gt> 0>.
 
 =item SSL_ERROR_ZERO_RETURN
 
-The TLS/SSL connection has been closed.  If the protocol version is SSL 3.0
-or TLS 1.0, this result code is returned only if a closure
-alert has occurred in the protocol, i.e. if the connection has been
-closed cleanly. Note that in this case B<SSL_ERROR_ZERO_RETURN>
-does not necessarily indicate that the underlying transport
-has been closed.
+The TLS/SSL connection has been closed.
+If the protocol version is SSL 3.0 or higher, this result code is returned only
+if a closure alert has occurred in the protocol, i.e. if the connection has been
+closed cleanly.
+Note that in this case B<SSL_ERROR_ZERO_RETURN> does not necessarily
+indicate that the underlying transport has been closed.
 
 =item SSL_ERROR_WANT_READ, SSL_ERROR_WANT_WRITE
 
@@ -112,12 +112,9 @@ thread has completed.
 
 =item SSL_ERROR_SYSCALL
 
-Some I/O error occurred.  The OpenSSL error queue may contain more
-information on the error.  If the error queue is empty
-(i.e. ERR_get_error() returns 0), B<ret> can be used to find out more
-about the error: If B<ret == 0>, an EOF was observed that violates
-the protocol.  If B<ret == -1>, the underlying B<BIO> reported an
-I/O error (for socket I/O on Unix systems, consult B<errno> for details).
+Some non-recoverable I/O error occurred.
+The OpenSSL error queue may contain more information on the error.
+For socket I/O on Unix systems, consult B<errno> for details.
 
 =item SSL_ERROR_SSL
 

doc/man3/SSL_read.pod

@@ -9,17 +9,17 @@ SSL_read_ex, SSL_read, SSL_peek_ex, SSL_peek
 
  #include <openssl/ssl.h>
 
- int SSL_read_ex(SSL *ssl, void *buf, size_t num, size_t *read);
+ int SSL_read_ex(SSL *ssl, void *buf, size_t num, size_t *readbytes);
  int SSL_read(SSL *ssl, void *buf, int num);
 
- int SSL_peek_ex(SSL *ssl, void *buf, size_t num, size_t *read);
+ int SSL_peek_ex(SSL *ssl, void *buf, size_t num, size_t *readbytes);
  int SSL_peek(SSL *ssl, void *buf, int num);
 
 =head1 DESCRIPTION
 
 SSL_read_ex() and SSL_read() try to read B<num> bytes from the specified B<ssl>
 into the buffer B<buf>. On success SSL_read_ex() will store the number of bytes
-actually read in B<*read>.
+actually read in B<*readbytes>.
 
 SSL_peek_ex() and SSL_peek() are identical to SSL_read_ex() and SSL_read()
 respectively except no bytes are actually removed from the underlying BIO during
@@ -90,38 +90,32 @@ with the same arguments.
 
 SSL_read_ex() and SSL_peek_ex() will return 1 for success or 0 for failure.
 Success means that 1 or more application data bytes have been read from the SSL
-connection. Failure means that no bytes could be read from the SSL connection.
+connection.
+Failure means that no bytes could be read from the SSL connection.
 Failures can be retryable (e.g. we are waiting for more bytes to
-be delivered by the network) or non-retryable (e.g. a fatal network error). In
-the event of a failure call L<SSL_get_error(3)> to find out the reason which
+be delivered by the network) or non-retryable (e.g. a fatal network error).
+In the event of a failure call L<SSL_get_error(3)> to find out the reason which
 indicates whether the call is retryable or not.
 
 For SSL_read() and SSL_peek() the following return values can occur:
 
 =over 4
 
-=item E<gt>0
+=item E<gt> 0
 
-The read operation was successful; the return value is the number of
-bytes actually read from the TLS/SSL connection.
+The read operation was successful.
+The return value is the number of bytes actually read from the TLS/SSL
+connection.
 
-=item Z<>0
+=item Z<><= 0
 
-The read operation was not successful. The reason may either be a clean
-shutdown due to a "close notify" alert sent by the peer (in which case
-the SSL_RECEIVED_SHUTDOWN flag in the ssl shutdown state is set
-(see L<SSL_shutdown(3)>,
-L<SSL_set_shutdown(3)>). It is also possible, that
-the peer simply shut down the underlying transport and the shutdown is
-incomplete. Call SSL_get_error() with the return value B<ret> to find out,
-whether an error occurred or the connection was shut down cleanly
-(SSL_ERROR_ZERO_RETURN).
+The read operation was not successful, because either the connection was closed,
+an error occurred or action must be taken by the calling process.
+Call L<SSL_get_error(3)> with the return value B<ret> to find out the reason.
 
-=item E<lt>0
-
-The read operation was not successful, because either an error occurred
-or action must be taken by the calling process. Call SSL_get_error() with the
-return value B<ret> to find out the reason.
+Old documentation indicated a difference between 0 and -1, and that -1 was
+retryable.
+You should instead call SSL_get_error() to find out if it's retryable.
 
 =back
 

doc/man3/SSL_write.pod

@@ -86,23 +86,20 @@ For SSL_write() the following return values can occur:
 
 =over 4
 
-=item E<gt>0
+=item E<gt> 0
 
 The write operation was successful, the return value is the number of
 bytes actually written to the TLS/SSL connection.
 
-=item Z<>0
+=item Z<><= 0
 
-The write operation was not successful. Probably the underlying connection
-was closed. Call SSL_get_error() with the return value B<ret> to find out,
-whether an error occurred or the connection was shut down cleanly
-(SSL_ERROR_ZERO_RETURN).
+The write operation was not successful, because either the connection was
+closed, an error occurred or action must be taken by the calling process.
+Call SSL_get_error() with the return value B<ret> to find out the reason.
 
-=item E<lt>0
-
-The write operation was not successful, because either an error occurred
-or action must be taken by the calling process. Call SSL_get_error() with the
-return value B<ret> to find out the reason.
+Old documentation indicated a difference between 0 and -1, and that -1 was
+retryable.
+You should instead call SSL_get_error() to find out if it's retryable.
 
 =back
 

include/openssl/ssl.h

@@ -1580,9 +1580,9 @@ __owur int SSL_get_changed_async_fds(SSL *s, OSSL_ASYNC_FD *addfd,
 __owur int SSL_accept(SSL *ssl);
 __owur int SSL_connect(SSL *ssl);
 __owur int SSL_read(SSL *ssl, void *buf, int num);
-__owur int SSL_read_ex(SSL *ssl, void *buf, size_t num, size_t *read);
+__owur int SSL_read_ex(SSL *ssl, void *buf, size_t num, size_t *readbytes);
 __owur int SSL_peek(SSL *ssl, void *buf, int num);
-__owur int SSL_peek_ex(SSL *ssl, void *buf, size_t num, size_t *read);
+__owur int SSL_peek_ex(SSL *ssl, void *buf, size_t num, size_t *readbytes);
 __owur int SSL_write(SSL *ssl, const void *buf, int num);
 __owur int SSL_write_ex(SSL *s, const void *buf, size_t num, size_t *written);
 long SSL_ctrl(SSL *ssl, int cmd, long larg, void *parg);

ssl/record/rec_layer_s3.c

@@ -178,10 +178,7 @@ const char *SSL_rstate_string(const SSL *s)
 }
 
 /*
- * Return values are as per SSL_read(), i.e.
- *  1 Success
- *  0 Failure (not retryable)
- * <0 Failure (may be retryable)
+ * Return values are as per SSL_read()
  */
 int ssl3_read_n(SSL *s, size_t n, size_t max, int extend, int clearold,
                 size_t *readbytes)
@@ -319,7 +316,7 @@ int ssl3_read_n(SSL *s, size_t n, size_t max, int extend, int clearold,
             if (s->mode & SSL_MODE_RELEASE_BUFFERS && !SSL_IS_DTLS(s))
                 if (len + left == 0)
                     ssl3_release_read_buffer(s);
-            return -1;
+            return ret;
         }
         left += bioread;
         /*
@@ -897,10 +894,7 @@ int do_ssl3_write(SSL *s, int type, const unsigned char *buf,
 
 /* if s->s3->wbuf.left != 0, we need to call this
  *
- * Return values are as per SSL_read(), i.e.
- *  1 Success
- *  0 Failure (not retryable)
- * <0 Failure (may be retryable)
+ * Return values are as per SSL_write()
  */
 int ssl3_write_pending(SSL *s, int type, const unsigned char *buf, size_t len,
                        size_t *written)
@@ -955,7 +949,7 @@ int ssl3_write_pending(SSL *s, int type, const unsigned char *buf, size_t len,
                  */
                 SSL3_BUFFER_set_left(&wb[currbuf], 0);
             }
-            return -1;
+            return (i);
         }
         SSL3_BUFFER_add_offset(&wb[currbuf], tmpwrit);
         SSL3_BUFFER_sub_left(&wb[currbuf], tmpwrit);

test/asynciotest.c

@@ -297,32 +297,59 @@ int main(int argc, char *argv[])
          * we hit at least one async event in both reading and writing
          */
         for (j = 0; j < 2; j++) {
+            int len;
+
             /*
              * Write some test data. It should never take more than 2 attempts
-             * (the first one might be a retryable fail). A zero return from
-             * SSL_write() is a non-retryable failure, so fail immediately if
-             * we get that.
+             * (the first one might be a retryable fail).
              */
-            for (ret = -1, i = 0; ret < 0 && i < 2 * sizeof(testdata); i++)
-                ret = SSL_write(clientssl, testdata, sizeof(testdata));
-            if (ret <= 0) {
-                printf("Test %d failed: Failed to write app data\n", test);
+            for (ret = -1, i = 0, len = 0; len != sizeof(testdata) && i < 2;
+                i++) {
+                ret = SSL_write(clientssl, testdata + len,
+                    sizeof(testdata) - len);
+                if (ret > 0) {
+                    len += ret;
+                } else {
+                    int ssl_error = SSL_get_error(clientssl, ret);
+
+                    if (ssl_error == SSL_ERROR_SYSCALL ||
+                        ssl_error == SSL_ERROR_SSL) {
+                        printf("Test %d failed: Failed to write app data\n", test);
+                        err = -1;
+                        goto end;
+                    }
+                }
+            }
+            if (len != sizeof(testdata)) {
+                err = -1;
+                printf("Test %d failed: Failed to write all app data\n", test);
                 goto end;
             }
             /*
              * Now read the test data. It may take more attemps here because
              * it could fail once for each byte read, including all overhead
-             * bytes from the record header/padding etc. Fail immediately if we
-             * get a zero return from SSL_read().
+             * bytes from the record header/padding etc.
              */
-            for (ret = -1, i = 0; ret < 0 && i < MAX_ATTEMPTS; i++)
-                ret = SSL_read(serverssl, buf, sizeof(buf));
-            if (ret <= 0) {
-                printf("Test %d failed: Failed to read app data\n", test);
-                goto end;
+            for (ret = -1, i = 0, len = 0; len != sizeof(testdata) &&
+                i < MAX_ATTEMPTS; i++)
+            {
+                ret = SSL_read(serverssl, buf + len, sizeof(buf) - len);
+                if (ret > 0) {
+                    len += ret;
+                } else {
+                    int ssl_error = SSL_get_error(serverssl, ret);
+
+                    if (ssl_error == SSL_ERROR_SYSCALL ||
+                        ssl_error == SSL_ERROR_SSL) {
+                        printf("Test %d failed: Failed to read app data\n", test);
+                        err = -1;
+                        goto end;
+                    }
+                }
             }
-            if (ret != sizeof(testdata)
+            if (len != sizeof(testdata)
                     || memcmp(buf, testdata, sizeof(testdata)) != 0) {
+                err = -1;
                 printf("Test %d failed: Unexpected app data received\n", test);
                 goto end;
             }