Fix read_ahead #1823
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Fix read_ahead #1823
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The function ssl3_read_n() takes a parameter |clearold| which, if set, causes any old data in the read buffer to be forgotten, and any unread data to be moved to the start of the buffer. This is supposed to happen when we first read the record header. However, the data move was only taking place if there was not already sufficient data in the buffer to satisfy the request. If read_ahead is set then the record header could be in the buffer already from when we read the preceding record. So with read_ahead we can get into a situation where even though |clearold| is set, the data does not get moved to the start of the read buffer when we read the record header. This means there is insufficient room in the read buffer to consume the rest of the record body, resulting in an internal error. This commit moves the |clearold| processing to earlier in ssl3_read_n() to ensure that it always takes place.
This test checks that read_ahead works correctly when dealing with large records.
levitte
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blblack
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Nov 2, 2016
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Merged. Thanks. |
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Description of change
The function ssl3_read_n() takes a parameter |clearold| which, if set, causes any old data in the read buffer to be forgotten, and any unread data to be moved to the start of the buffer. This is supposed to happen when we first read the record header.
However, the data move was only taking place if there was not already sufficient data in the buffer to satisfy the request. If read_ahead is set then the record header could be in the buffer already from when we read the preceding record. So with read_ahead we can get into a situation where even though |clearold| is set, the data does not get moved to the start of the read buffer when we read the record header. This means there is insufficient room in the read buffer to consume the rest of the record body, resulting in an internal error.
This PR moves the |clearold| processing to earlier in ssl3_read_n() to ensure that it always takes place.
Fixes #1799