Issue Description
When a prepared statement is issued with a high enough number of parameters an invalid resulset (no resulset) is received from server side. Both client libraries `libmysqlclient` and `libmariadbclient` has been tested against a MariaDB backend, leading to the same result. A minimal test case that can be compiled against both of these libraries, together with traffic captures is provided for reproducing the issue.
Errors reported by client libraries
libmysqlclient:
error: 'Attempt to read a row while there is no result set associated with the statement'
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libmariadbclient:
error: 'Commands out of sync; you can't run this command now'
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Error reported in MariaDB error log
2022-03-11 12:27:00 1708 [Warning] Aborted connection 1708 to db: 'unconnected' user: 'root' host: '127.0.0.1' (Got an error reading communication packets)
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2022-03-11 12:27:03 1709 [Warning] Aborted connection 1709 to db: 'unconnected' user: 'root' host: '127.0.0.1' (Got an error reading communication packets)
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Traffic captures showing the issue:
In the following traffic captures it can be seen valid requests (COM_STMT_EXECUTE) and the responses from MariaDB.
Valid request - COM_STMT_EXECUTE - libmariadb_valid_stmt_response.pcapng:
Frame 16: 2006 bytes on wire (16048 bits), 2006 bytes captured (16048 bits) on interface any, id 0
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Linux cooked capture v1
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Internet Protocol Version 4, Src: 127.0.0.1, Dst: 127.0.0.1
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Transmission Control Protocol, Src Port: 49516, Dst Port: 3306, Seq: 10703, Ack: 28346, Len: 1938
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[2 Reassembled TCP Segments (10130 bytes): #15(8192), #16(1938)]
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MySQL Protocol
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Packet Length: 10126
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Packet Number: 0
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Request Command Execute Statement
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Valid response - BinaryProtocolResulset - libmariadb_valid_stmt_response.pcapng:
Frame 17: 286 bytes on wire (2288 bits), 286 bytes captured (2288 bits) on interface any, id 0
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Linux cooked capture v1
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Internet Protocol Version 4, Src: 127.0.0.1, Dst: 127.0.0.1
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Transmission Control Protocol, Src Port: 3306, Dst Port: 49516, Seq: 28346, Ack: 12641, Len: 218
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MySQL Protocol
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... { More packets } ...
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MySQL Protocol
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Packet Length: 5
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Packet Number: 7
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Response Code: EOF Packet (0xfe)
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EOF marker: 254
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Warnings: 0
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Server Status: 0x0000
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Payload: 2200
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Offending request - COM_STMT_EXECUTE - libmariadb_invalid_stmt_response.pcapng:
Frame 16: 2016 bytes on wire (16128 bits), 2016 bytes captured (16128 bits) on interface any, id 0
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Linux cooked capture v1
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Internet Protocol Version 4, Src: 127.0.0.1, Dst: 127.0.0.1
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Transmission Control Protocol, Src Port: 49514, Dst Port: 3306, Seq: 10705, Ack: 28374, Len: 1948
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[2 Reassembled TCP Segments (10140 bytes): #15(8192), #16(1948)]
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MySQL Protocol
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Packet Length: 10136
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Packet Number: 0
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Request Command Execute Statement
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Invalid Response - libmariadb_invalid_stmt_response.pcapng:
Expected BinaryProtocolResulset, received just OK packet:
Frame 17: 79 bytes on wire (632 bits), 79 bytes captured (632 bits) on interface any, id 0
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Linux cooked capture v1
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Internet Protocol Version 4, Src: 127.0.0.1, Dst: 127.0.0.1
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Transmission Control Protocol, Src Port: 3306, Dst Port: 49514, Seq: 28374, Ack: 12653, Len: 11
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MySQL Protocol
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Packet Length: 7
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Packet Number: 1
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Response Code: OK Packet (0x00)
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Prefix: 0
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Length: 0
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Prefix: 0
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Length: 0
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Affected Rows: 0
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Prefix: 0
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Length: 0
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Server Status: 0x0002
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Warnings: 0
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Issue Reproduction
Script compilation
Against `libmysqlclient`:
g++ -DLIBMYSQLCLIENT test_stmt_large_param_num.cpp -I/usr/include/mysql -ldl -std=c++11 -lmysqlclient -o libmysql_test_stmt_large_param_num
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Against `libmariadbclient`:
g++ test_stmt_large_param_num.cpp -I/usr/include/mysql -ldl -std=c++11 -lmariadbclient -o libmariadb_test_stmt_large_param_num
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Script usage
Using the provided test script it's just enough to use it against a MariaDB, and the issue will be reproduce, script usage is the following:
test_stmt_large_param_num -h <mysql host> -u <mysql user> -p <mysql password> -P <mysql port> -N <stmt_param_num>
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Where '-N' specifies the number of parameters to be created for the stmt to be issued. Simple testing using the script via:
for i in {500..2000}; do ./libmariadb_test_stmt_large_param_num -h '127.0.0.1' -u root -p root -P 3306 -N $i; if [ $? -ne 0 ]; then echo ArgNum: $i - $(date); break; fi; done
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Revealed that `1000` appears to be the offending number of parameters that triggers the issue, at least in the used testing environment.
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libmariadb_invalid_stmt_response.pcapng