MXS-1275: Add custom parser for "SET SQL_MODE=..."

SetSqlModeParser is a custom parser for detecting "SET SQL_MODE=..."
statements. It will be used in mysql_client and the result will be
used for updating the sql_mode of a session (that is to be added).

Thereafter, whenever a statement arrives, the value of that sql_mode
will be used for setting the mode of the query_classifier.

server/modules/protocol/MySQL/MySQLClient/CMakeLists.txt

@@ -2,3 +2,7 @@ add_library(MySQLClient SHARED mysql_client.cc)
 target_link_libraries(MySQLClient maxscale-common  MySQLCommon)
 set_target_properties(MySQLClient PROPERTIES VERSION "1.0.0")
 install_module(MySQLClient core)
+
+if(BUILD_TESTS)
+  add_subdirectory(test)
+endif()

server/modules/protocol/MySQL/MySQLClient/setsqlmodeparser.hh

@@ -0,0 +1,617 @@
+#pragma once
+/*
+ * Copyright (c) 2016 MariaDB Corporation Ab
+ *
+ * Use of this software is governed by the Business Source License included
+ * in the LICENSE.TXT file and at www.mariadb.com/bsl11.
+ *
+ * Change Date: 2019-07-01
+ *
+ * On the date above, in accordance with the Business Source License, use
+ * of this software will be governed by version 2 or later of the General
+ * Public License.
+ */
+
+#include <maxscale/cppdefs.hh>
+#include <maxscale/customparser.hh>
+#include <maxscale/protocol/mysql.h>
+
+
+class SetSqlModeParser : public maxscale::CustomParser
+{
+public:
+    enum sql_mode_t
+    {
+        DEFAULT,   // "set sql_mode=DEFAULT"
+        ORACLE,    // "set sql_mode=ORACLE", "set sql_mode='PIPES_AS_CONCAT,ORACLE', autocommit=false", etc.
+        SOMETHING  // "set sql_mode=PIPES_AS_CONCAT"
+    };
+
+    enum result_t
+    {
+        ERROR,           // Some fatal error occurred; mem alloc failed, parsing failed, etc.
+        IS_SET_SQL_MODE, // The COM_QUERY is "set sql_mode=..."
+        NOT_SET_SQL_MODE // The COM_QUERY is NOT "set sql_mode=..."
+    };
+
+    enum
+    {
+        UNUSED_FIRST = 0xFF,
+        TK_DEFAULT,
+        TK_GLOBAL,
+        TK_ORACLE,
+        TK_SESSION,
+        TK_SET,
+        TK_SQL_MODE,
+    };
+
+    SetSqlModeParser()
+    {
+    }
+
+    /**
+     * Return whether the statement is a "SET SQL_MODE=" statement and if so,
+     * whether the state is ORACLE, DEFAULT or something else.
+     *
+     * @param ppBuffer   Address of pointer to buffer containing statement.
+     *                   The GWBUF must contain a complete statement, but the
+     *                   buffer need not be contiguous.
+     * @param pSql_mode  Pointer to variable receiving the sql_mode state, if
+     *                   the statement is a "SET SQL_MODE=" statement.
+     *
+     * @return ERROR            if a fatal error occurred during parsing
+     *         IS_SET_SQL_MODE  if the statement is a "SET SQL_MODE=" statement
+     *         NOT_SET_SQL_MODE if the statement is not a "SET SQL_MODE="
+     *                          statement
+     *
+     * @attention If the result cannot be deduced without parsing the statement,
+     *            then the buffer will be made contiguous and the value of
+     *            @c *ppBuffer will be updated accordingly.
+     */
+    result_t get_sql_mode(GWBUF** ppBuffer, sql_mode_t* pSql_mode)
+    {
+        result_t rv = NOT_SET_SQL_MODE;
+
+        GWBUF* pBuffer = *ppBuffer;
+
+        ss_dassert(gwbuf_length(pBuffer) >= MYSQL_HEADER_LEN);
+
+        size_t buf_len = GWBUF_LENGTH(pBuffer);
+        size_t payload_len;
+        if (buf_len >= MYSQL_HEADER_LEN)
+        {
+            // The first buffer in the chain contains the header so we
+            // can read the length directly.
+            payload_len = MYSQL_GET_PAYLOAD_LEN(GWBUF_DATA(pBuffer));
+        }
+        else
+        {
+            // The first buffer in the chain does not contain the full
+            // header so we need to copy it first.
+            uint8_t header[MYSQL_HEADER_LEN];
+            gwbuf_copy_data(pBuffer, 0, sizeof(header), header);
+            payload_len = MYSQL_GET_PAYLOAD_LEN(header);
+        }
+
+        if (payload_len >= 20) // sizeof(command byte) + strlen("SET sql_mode=ORACLE"), the minimum needed.
+        {
+            // We need 4 bytes from the payload to deduce whether more investigations are needed.
+            uint8_t payload[4];
+            uint8_t* pPayload;
+
+            if (buf_len >= MYSQL_HEADER_LEN + sizeof(payload))
+            {
+                // Enough data in the first buffer of the chain, we can access directly.
+                pPayload = GWBUF_DATA(pBuffer) + MYSQL_HEADER_LEN;
+            }
+            else
+            {
+                // Not enough, we copy what we need.
+                gwbuf_copy_data(pBuffer, MYSQL_HEADER_LEN, sizeof(payload), payload);
+                pPayload = payload;
+            }
+
+            uint8_t command = pPayload[0];
+
+            if (command == MYSQL_COM_QUERY)
+            {
+                const uint8_t* pStmt = &pPayload[1];
+
+                if (is_alpha(*pStmt))
+                {
+                    // First character is alphabetic, we can check whether it is "SET".
+                    if (is_set(pStmt))
+                    {
+                        // It is, so we must parse further and must therefore ensure that
+                        // the buffer is contiguous. We get the same buffer back if it
+                        // already is.
+                        pBuffer = gwbuf_make_contiguous(*ppBuffer);
+
+                        if (pBuffer)
+                        {
+                            *ppBuffer = pBuffer;
+                            initialize(pBuffer);
+
+                            rv = parse(pSql_mode);
+                        }
+                        else
+                        {
+                            rv = ERROR;
+                        }
+                    }
+                }
+                else
+                {
+                    // If the first character is not an alphabetic character we assume there
+                    // is a comment and make the buffer contiguous to make it possible to
+                    // efficiently bypass the whitespace.
+                    pBuffer = gwbuf_make_contiguous(*ppBuffer);
+
+                    if (pBuffer)
+                    {
+                        *ppBuffer = pBuffer;
+                        initialize(pBuffer);
+
+                        bypass_whitespace();
+
+                        if (is_set(m_pI))
+                        {
+                            rv = parse(pSql_mode);
+                        }
+                    }
+                    else
+                    {
+                        rv = ERROR;
+                    }
+                }
+            }
+        }
+
+        return rv;
+    }
+
+    /**
+     * Returns a @c sql_mode_t as a string.
+     *
+     * @param sql_mode  An SQL mode.
+     *
+     * @return The corresponding string.
+     */
+    static const char* to_string(sql_mode_t sql_mode)
+    {
+        switch (sql_mode)
+        {
+        case DEFAULT:
+            return "DEFAULT";
+
+        case ORACLE:
+            return "ORACLE";
+
+        case SOMETHING:
+            return "SOMETHING";
+
+        default:
+            ss_dassert(!true);
+            return "UNKNOWN";
+        }
+    }
+
+    /**
+     * Returns a @c result_t as a string.
+     *
+     * @param result_t  A result.
+     *
+     * @return The corresponding string.
+     */
+    static const char* to_string(result_t result)
+    {
+        switch (result)
+        {
+        case ERROR:
+            return "ERROR";
+
+        case IS_SET_SQL_MODE:
+            return "IS_SET_SQL_MODE";
+
+        case NOT_SET_SQL_MODE:
+            return "NOT_SET_SQL_MODE";
+
+        default:
+            ss_dassert(!true);
+            return "UNKNOWN";
+        }
+    }
+
+private:
+    static bool is_set(const char* pStmt)
+    {
+        return
+            (pStmt[0] == 's' || pStmt[0] == 'S') &&
+            (pStmt[1] == 'e' || pStmt[1] == 'E') &&
+            (pStmt[2] == 't' || pStmt[2] == 'T');
+    }
+
+    static bool is_set(const uint8_t* pStmt)
+    {
+        return is_set(reinterpret_cast<const char*>(pStmt));
+    }
+
+    static bool is_error(result_t rv)
+    {
+        return (rv == ERROR);
+    }
+
+    result_t initialize(GWBUF* pBuffer)
+    {
+        ss_dassert(GWBUF_IS_CONTIGUOUS(pBuffer));
+
+        result_t rv = ERROR;
+
+        char* pSql;
+        if (modutil_extract_SQL(pBuffer, &pSql, &m_len))
+        {
+            m_pSql = pSql;
+            m_pI = m_pSql;
+            m_pEnd = m_pI + m_len;
+        }
+
+        return ERROR;
+    }
+
+    bool consume_id()
+    {
+        // Consumes "[a-zA-Z]([a-zA-Z0-9_])*
+
+        bool rv = false;
+
+        if (is_alpha(*m_pI))
+        {
+            rv = true;
+
+            ++m_pI;
+
+            while ((m_pI < m_pEnd) && (is_alpha(*m_pI) || is_number(*m_pI) || (*m_pI == '_')))
+            {
+                ++m_pI;
+            }
+        }
+
+        return rv;
+    }
+
+    void consume_value()
+    {
+        // Consumes everything until a ',' outside of a commented string, or eol is
+        // encountered.
+        bool rv = false;
+        bool consumed = false;
+
+        while ((m_pI < m_pEnd) && (*m_pI != ','))
+        {
+            switch (*m_pI)
+            {
+            case '\'':
+            case '"':
+            case '`':
+                {
+                    char quote = *m_pI;
+                    ++m_pI;
+                    while ((m_pI < m_pEnd) && (*m_pI != quote))
+                    {
+                        ++m_pI;
+                    }
+                }
+                break;
+
+            default:
+                ++m_pI;
+            }
+        }
+    }
+
+    result_t parse(sql_mode_t* pSql_mode)
+    {
+        result_t rv = NOT_SET_SQL_MODE;
+        token_t token = next_token();
+
+        switch (token)
+        {
+        case TK_SET:
+            rv = parse_set(pSql_mode);
+            break;
+
+        case PARSER_EXHAUSTED:
+            log_exhausted();
+            break;
+
+        case PARSER_UNKNOWN_TOKEN:
+        default:
+            log_unexpected();
+            break;
+        }
+
+        return rv;
+    }
+
+    result_t parse_set(sql_mode_t* pSql_mode)
+    {
+        result_t rv = NOT_SET_SQL_MODE;
+
+        char c;
+
+        do
+        {
+            token_t token = next_token();
+
+            switch (token)
+            {
+            case TK_GLOBAL:
+                rv = parse_set(pSql_mode);
+                break;
+
+            case TK_SESSION:
+                rv = parse_set(pSql_mode);
+                break;
+
+            case TK_SQL_MODE:
+                if (next_token() == '=')
+                {
+                    rv = parse_set_sql_mode(pSql_mode);
+                }
+                else
+                {
+                    rv = ERROR;
+                }
+                break;
+
+            case PARSER_EXHAUSTED:
+                log_exhausted();
+                rv = ERROR;
+                break;
+
+            case PARSER_UNKNOWN_TOKEN:
+                // Might be something like "SET A=B, C=D, SQL_MODE=ORACLE", so we first consume
+                // the identifier and if it is followed by a "=" we consume the value.
+                {
+                    char c;
+                    if (consume_id() && peek_next_char(&c) && (c == '='))
+                    {
+                        consume_value();
+                    }
+                    else
+                    {
+                        log_unexpected();
+                        rv = ERROR;
+                    }
+                }
+                break;
+
+            default:
+                log_unexpected();
+                rv = ERROR;
+                break;
+            }
+
+            c = 0;
+
+            if (rv != ERROR)
+            {
+                if (peek_next_char(&c))
+                {
+                    if (c == ',')
+                    {
+                        ++m_pI;
+                    }
+                    else
+                    {
+                        c = 0;
+                    }
+                }
+                else
+                {
+                    c = 0;
+                }
+            }
+        }
+        while (c == ',');
+
+        return rv;
+    }
+
+    result_t parse_set_sql_mode(sql_mode_t* pSql_mode)
+    {
+        result_t rv = IS_SET_SQL_MODE;
+
+        token_t token = next_token();
+
+        switch (token)
+        {
+        case '\'':
+        case '"':
+        case '`':
+            rv = parse_set_sql_mode_string(token, pSql_mode);
+            break;
+
+        case TK_DEFAULT:
+            *pSql_mode = DEFAULT;
+            break;
+
+        case TK_ORACLE:
+            *pSql_mode = ORACLE;
+            break;
+
+        case PARSER_UNKNOWN_TOKEN:
+            if (consume_id())
+            {
+                *pSql_mode = SOMETHING;
+            }
+            else
+            {
+                rv = ERROR;
+            }
+            break;
+
+        default:
+            rv = ERROR;
+        }
+
+        return rv;
+    }
+
+    result_t parse_set_sql_mode_string(char quote, sql_mode_t* pSql_mode)
+    {
+        result_t rv = IS_SET_SQL_MODE;
+
+        char c;
+
+        do
+        {
+            rv = parse_set_sql_mode_setting(pSql_mode);
+
+            if (!is_error(rv))
+            {
+                if (peek_next_char(&c) && (c == ','))
+                {
+                    ++m_pI;
+                }
+            }
+        }
+        while (!is_error(rv) && (c == ','));
+
+        return rv;
+    }
+
+    result_t parse_set_sql_mode_setting(sql_mode_t* pSql_mode)
+    {
+        result_t rv = IS_SET_SQL_MODE;
+
+        token_t token = next_token();
+
+        switch (token)
+        {
+        case TK_ORACLE:
+            *pSql_mode = ORACLE;
+            break;
+
+        case PARSER_UNKNOWN_TOKEN:
+            if (consume_id())
+            {
+                *pSql_mode = SOMETHING;
+            }
+            else
+            {
+                rv = ERROR;
+            }
+            break;
+
+        case PARSER_EXHAUSTED:
+            log_exhausted();
+            rv = ERROR;
+            break;
+
+        default:
+            log_unexpected();
+            rv = ERROR;
+        }
+
+        return rv;
+    }
+
+    token_t next_token(token_required_t required = TOKEN_NOT_REQUIRED)
+    {
+        token_t token = PARSER_UNKNOWN_TOKEN;
+
+        bypass_whitespace();
+
+        if (m_pI == m_pEnd)
+        {
+            token = PARSER_EXHAUSTED;
+        }
+        else if (*m_pI == ';')
+        {
+            ++m_pI;
+
+            while ((m_pI != m_pEnd) && isspace(*m_pI))
+            {
+                ++m_pI;
+            }
+
+            if (m_pI != m_pEnd)
+            {
+                MXS_WARNING("Non-space data found after semi-colon: '%.*s'.",
+                            (int)(m_pEnd - m_pI), m_pI);
+            }
+
+            token = PARSER_EXHAUSTED;
+        }
+        else
+        {
+            switch (*m_pI)
+            {
+            case '@':
+                if (is_next_alpha('S', 2))
+                {
+                    token = expect_token(MXS_CP_EXPECT_TOKEN("@@SESSION"), TK_SESSION);
+                }
+                else if (is_next_alpha('G', 2))
+                {
+                    token = expect_token(MXS_CP_EXPECT_TOKEN("@@GLOBAL"), TK_GLOBAL);
+                }
+                break;
+
+            case '\'':
+            case '"':
+            case '`':
+            case ',':
+            case '=':
+                token = *m_pI;
+                ++m_pI;
+                break;
+
+            case 'd':
+            case 'D':
+                token = expect_token(MXS_CP_EXPECT_TOKEN("DEFAULT"), TK_DEFAULT);
+                break;
+
+            case 'g':
+            case 'G':
+                token = expect_token(MXS_CP_EXPECT_TOKEN("GLOBAL"), TK_GLOBAL);
+                break;
+
+            case 'o':
+            case 'O':
+                token = expect_token(MXS_CP_EXPECT_TOKEN("ORACLE"), TK_ORACLE);
+                break;
+
+            case 's':
+            case 'S':
+                if (is_next_alpha('E'))
+                {
+                    if (is_next_alpha('S', 2))
+                    {
+                        token = expect_token(MXS_CP_EXPECT_TOKEN("SESSION"), TK_SESSION);
+                    }
+                    else
+                    {
+                        token = expect_token(MXS_CP_EXPECT_TOKEN("SET"), TK_SET);
+                    }
+                }
+                else if (is_next_alpha('Q'))
+                {
+                    token = expect_token(MXS_CP_EXPECT_TOKEN("SQL_MODE"), TK_SQL_MODE);
+                }
+                break;
+
+            default:
+                ;
+            }
+        }
+
+        if ((token == PARSER_EXHAUSTED) && (required == TOKEN_REQUIRED))
+        {
+            log_exhausted();
+        }
+
+        return token;
+    }
+};

server/modules/protocol/MySQL/MySQLClient/test/CMakeLists.txt

@@ -0,0 +1,3 @@
+add_executable(test_setsqlmodeparser test_setsqlmodeparser.cc)
+target_link_libraries(test_setsqlmodeparser maxscale-common)
+add_test(test_setsqlmodeparser test_setsqlmodeparser)

server/modules/protocol/MySQL/MySQLClient/test/test_setsqlmodeparser.cc

@@ -0,0 +1,174 @@
+/*
+ * Copyright (c) 2016 MariaDB Corporation Ab
+ *
+ * Use of this software is governed by the Business Source License included
+ * in the LICENSE.TXT file and at www.mariadb.com/bsl11.
+ *
+ * Change Date: 2019-07-01
+ *
+ * On the date above, in accordance with the Business Source License, use
+ * of this software will be governed by version 2 or later of the General
+ * Public License.
+ */
+
+#include "../setsqlmodeparser.hh"
+#include <stdlib.h>
+#include <iostream>
+#include <maxscale/buffer.h>
+#include <maxscale/paths.h>
+
+using namespace std;
+
+namespace
+{
+
+GWBUF* create_gwbuf(const char* zStmt)
+{
+    size_t len = strlen(zStmt);
+    size_t payload_len = len + 1;
+    size_t gwbuf_len = MYSQL_HEADER_LEN + payload_len;
+
+    GWBUF* pBuf = gwbuf_alloc(gwbuf_len);
+
+    *((unsigned char*)((char*)GWBUF_DATA(pBuf))) = payload_len;
+    *((unsigned char*)((char*)GWBUF_DATA(pBuf) + 1)) = (payload_len >> 8);
+    *((unsigned char*)((char*)GWBUF_DATA(pBuf) + 2)) = (payload_len >> 16);
+    *((unsigned char*)((char*)GWBUF_DATA(pBuf) + 3)) = 0x00;
+    *((unsigned char*)((char*)GWBUF_DATA(pBuf) + 4)) = 0x03;
+    memcpy((char*)GWBUF_DATA(pBuf) + 5, zStmt, len);
+
+    return pBuf;
+}
+
+}
+
+namespace
+{
+
+typedef SetSqlModeParser P;
+
+struct TEST_CASE
+{
+    const char*                  zStmt;
+    SetSqlModeParser::result_t   result;
+    SetSqlModeParser::sql_mode_t sql_mode;
+} test_cases[] =
+{
+    { "SET SQL_MODE=DEFAULT",
+      P::IS_SET_SQL_MODE, P::DEFAULT },
+    { "/*blah*/ SET /*blah*/ SQL_MODE /*blah*/ = /*blah*/ DEFAULT /*blah*/ ",
+      P::IS_SET_SQL_MODE, P::DEFAULT },
+    { "SET SQL_MODE=ORACLE",
+      P::IS_SET_SQL_MODE, P::ORACLE },
+    { "SET SQL_MODE=BLAH",              // So short that it cannot be DEFAULT|ORACLE
+      P::NOT_SET_SQL_MODE,  P::ORACLE },
+    { "SET SQL_MODE='BLAH'",
+      P::IS_SET_SQL_MODE, P::SOMETHING },
+    { "SET SQL_MODE=BLAHBLAH",
+      P::IS_SET_SQL_MODE, P::SOMETHING },
+    { "SET SQL_MODE='ORACLE'",
+      P::IS_SET_SQL_MODE, P::ORACLE },
+    { "SET SQL_MODE='BLAH, A, B, ORACLE'",
+      P::IS_SET_SQL_MODE, P::ORACLE },
+    { "SET SQL_MODE='BLAH, A, B, XYZ_123'",
+      P::IS_SET_SQL_MODE, P::SOMETHING },
+    { "SET VAR1=1234, VAR2=3456, SQL_MODE='A,B, ORACLE'",
+      P::IS_SET_SQL_MODE, P::ORACLE },
+    { "SET SQL_MODE=ORACLE, VAR1=3456, VAR2='A=b, c=d', SQL_MODE='A,B, ORACLE'",
+      P::IS_SET_SQL_MODE, P::ORACLE },
+};
+
+const int N_TEST_CASES = sizeof(test_cases)/sizeof(test_cases[0]);
+
+int test(const TEST_CASE& test_case)
+{
+    int rv = EXIT_SUCCESS;
+
+    cout << test_case.zStmt << ": ";
+
+    GWBUF* pStmt = create_gwbuf(test_case.zStmt);
+    ss_dassert(pStmt);
+
+    SetSqlModeParser parser;
+
+    SetSqlModeParser::sql_mode_t sql_mode;
+    SetSqlModeParser::result_t result = parser.get_sql_mode(&pStmt, &sql_mode);
+    gwbuf_free(pStmt);
+
+    if (result == test_case.result)
+    {
+        if (result == SetSqlModeParser::IS_SET_SQL_MODE)
+        {
+            if (sql_mode == test_case.sql_mode)
+            {
+                cout << "OK";
+            }
+            else
+            {
+                cout << "ERROR: Expected "
+                     << "'" << SetSqlModeParser::to_string(test_case.sql_mode) << "'"
+                     << ", got "
+                     << "'" << SetSqlModeParser::to_string(sql_mode) << "'"
+                     << ".";
+                rv = EXIT_FAILURE;
+            }
+        }
+        else
+        {
+            cout << "OK";
+        }
+    }
+    else
+    {
+        cout << "ERROR: Expected "
+             << "'" << SetSqlModeParser::to_string(test_case.result) << "'"
+             << ", got "
+             << "'" << SetSqlModeParser::to_string(result) << "'"
+             << ".";
+        rv = EXIT_FAILURE;
+    }
+
+    cout << endl;
+
+    return rv;
+}
+
+int test()
+{
+    int rv = EXIT_SUCCESS;
+
+    for (int i = 0; i < N_TEST_CASES; ++i)
+    {
+        if (test(test_cases[i]) == EXIT_FAILURE)
+        {
+            rv = EXIT_FAILURE;
+        }
+    }
+
+    return rv;
+}
+
+}
+
+
+int main(int argc, char* argv[])
+{
+    int rc = EXIT_SUCCESS;
+
+    set_datadir(strdup("/tmp"));
+    set_langdir(strdup("."));
+    set_process_datadir(strdup("/tmp"));
+
+    if (mxs_log_init(NULL, ".", MXS_LOG_TARGET_DEFAULT))
+    {
+        rc = test();
+
+        mxs_log_finish();
+    }
+    else
+    {
+        cerr << "error: Could not initialize log." << endl;
+    }
+
+    return rc;
+}