SQL: add support for passing query parameters in REST API calls

docs/reference/sql/endpoints/rest.asciidoc

@@ -8,6 +8,7 @@
 * <<sql-pagination>>
 * <<sql-rest-filtering>>
 * <<sql-rest-columnar>>
+* <<sql-rest-params>>
 * <<sql-rest-fields>>
 
 [[sql-rest-overview]]
@@ -337,7 +338,7 @@ Which will like return the
 [[sql-rest-filtering]]
 === Filtering using {es} query DSL
 
-You can filter the results that SQL will run on using a standard
+One can filter the results that SQL will run on using a standard
 {es} query DSL by specifying the query in the filter
 parameter.
 
@@ -442,6 +443,36 @@ Which looks like:
 --------------------------------------------------
 // TESTRESPONSE[s/46ToAwFzQERYRjFaWEo1UVc1a1JtVjBZMmdCQUFBQUFBQUFBQUVXWjBaNlFXbzNOV0pVY21Wa1NUZDJhV2t3V2xwblp3PT3\/\/\/\/\/DwQBZgZhdXRob3IBBHRleHQAAAFmBG5hbWUBBHRleHQAAAFmCnBhZ2VfY291bnQBBGxvbmcBAAFmDHJlbGVhc2VfZGF0ZQEIZGF0ZXRpbWUBAAEP/$body.cursor/]
 
+[[sql-rest-params]]
+=== Passing parameters to a query
+
+Using values in a query condition, for example, or in a `HAVING` statement can be done "inline",
+by integrating the value in the query string itself:
+
+[source,console]
+--------------------------------------------------
+POST /_sql?format=txt
+{
+	"query": "SELECT YEAR(release_date) AS year FROM library WHERE page_count > 300 AND author = 'Frank Herbert' GROUP BY year HAVING COUNT(*) > 0"
+}
+--------------------------------------------------
+// TEST[setup:library]
+
+or it can be done by extracting the values in a separate list of parameters and using question mark placeholders (`?`) in the query string:
+
+[source,console]
+--------------------------------------------------
+POST /_sql?format=txt
+{
+	"query": "SELECT YEAR(release_date) AS year FROM library WHERE page_count > ? AND author = ? GROUP BY year HAVING COUNT(*) > ?",
+	"params": [300, "Frank Herbert", 0]
+}
+--------------------------------------------------
+// TEST[setup:library]
+
+[IMPORTANT]
+The recommended way of passing values to a query is with question mark placeholders, to avoid any attempts of hacking or SQL injection.
+
 [[sql-rest-fields]]
 === Supported REST parameters
 
@@ -495,6 +526,10 @@ More information available https://docs.oracle.com/javase/8/docs/api/java/time/Z
 |false
 |Whether to include <<frozen-indices, frozen-indices>> in the query execution or not (default).
 
+|params
+|none
+|Optional list of parameters to replace question mark (`?`) placeholders inside the query.
+
 |===
 
 Do note that most parameters (outside the timeout and `columnar` ones) make sense only during the initial query - any follow-up pagination request only requires the `cursor` parameter as explained in the <<sql-pagination, pagination>> chapter.

x-pack/plugin/sql/qa/src/main/java/org/elasticsearch/xpack/sql/qa/rest/RestSqlTestCase.java

@@ -538,8 +538,11 @@ public void testBasicQueryWithParameters() throws IOException {
         } else {
             expected.put("rows", Arrays.asList(Arrays.asList("foo", 10)));
         }
+
+        String params = mode.equals("jdbc") ? "{\"type\": \"integer\", \"value\": 10}, {\"type\": \"keyword\", \"value\": \"foo\"}" :
+            "10, \"foo\"";
         assertResponse(expected, runSql(new StringEntity("{\"query\":\"SELECT test, ? param FROM test WHERE test = ?\", " +
-                "\"params\":[{\"type\": \"integer\", \"value\": 10}, {\"type\": \"keyword\", \"value\": \"foo\"}]"
+                "\"params\":[" + params + "]"
                 + mode(mode) + columnarParameter(columnar) + "}", ContentType.APPLICATION_JSON), StringUtils.EMPTY, mode));
     }
 

x-pack/plugin/sql/sql-action/src/main/java/org/elasticsearch/xpack/sql/action/AbstractSqlQueryRequest.java

@@ -12,7 +12,12 @@
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.unit.TimeValue;
 import org.elasticsearch.common.xcontent.ObjectParser;
+import org.elasticsearch.common.xcontent.ObjectParser.ValueType;
 import org.elasticsearch.common.xcontent.ToXContentFragment;
+import org.elasticsearch.common.xcontent.XContentLocation;
+import org.elasticsearch.common.xcontent.XContentParseException;
+import org.elasticsearch.common.xcontent.XContentParser;
+import org.elasticsearch.common.xcontent.XContentParser.Token;
 import org.elasticsearch.index.query.AbstractQueryBuilder;
 import org.elasticsearch.index.query.QueryBuilder;
 import org.elasticsearch.xpack.sql.proto.Mode;
@@ -22,6 +27,7 @@
 
 import java.io.IOException;
 import java.time.ZoneId;
+import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 import java.util.Objects;
@@ -75,11 +81,11 @@ protected static <R extends AbstractSqlQueryRequest> ObjectParser<R, Void> objec
         parser.declareString(AbstractSqlQueryRequest::query, QUERY);
         parser.declareString((request, mode) -> request.mode(Mode.fromString(mode)), MODE);
         parser.declareString((request, clientId) -> request.clientId(clientId), CLIENT_ID);
-        parser.declareObjectArray(AbstractSqlQueryRequest::params, (p, c) -> SqlTypedParamValue.fromXContent(p), PARAMS);
+        parser.declareField(AbstractSqlQueryRequest::params, AbstractSqlQueryRequest::parseParams, PARAMS, ValueType.VALUE_ARRAY);
         parser.declareString((request, zoneId) -> request.zoneId(ZoneId.of(zoneId)), TIME_ZONE);
         parser.declareInt(AbstractSqlQueryRequest::fetchSize, FETCH_SIZE);
         parser.declareString((request, timeout) -> request.requestTimeout(TimeValue.parseTimeValue(timeout, Protocol.REQUEST_TIMEOUT,
-            "request_timeout")), REQUEST_TIMEOUT);
+                "request_timeout")), REQUEST_TIMEOUT);
         parser.declareString(
                 (request, timeout) -> request.pageTimeout(TimeValue.parseTimeValue(timeout, Protocol.PAGE_TIMEOUT, "page_timeout")),
                 PAGE_TIMEOUT);
@@ -117,6 +123,87 @@ public AbstractSqlQueryRequest params(List<SqlTypedParamValue> params) {
         this.params = params;
         return this;
     }
+
+    private static List<SqlTypedParamValue> parseParams(XContentParser p) throws IOException {
+        List<SqlTypedParamValue> result = new ArrayList<>();
+        Token token = p.currentToken();
+
+        if (token == Token.START_ARRAY) {
+            Object value = null;
+            String type = null;
+            SqlTypedParamValue previousParam = null;
+            SqlTypedParamValue currentParam = null;
+
+            while ((token = p.nextToken()) != Token.END_ARRAY) {
+                XContentLocation loc = p.getTokenLocation();
+
+                if (token == Token.START_OBJECT) {
+                    // we are at the start of a value/type pair... hopefully
+                    currentParam = SqlTypedParamValue.fromXContent(p);
+                    /*
+                     * Always set the xcontentlocation for the first param just in case the first one happens to not meet the parsing rules
+                     * that are checked later in validateParams method.
+                     * Also, set the xcontentlocation of the param that is different from the previous param in list when it comes to 
+                     * its type being explicitly set or inferred.
+                     */
+                    if ((previousParam != null && previousParam.hasExplicitType() == false) || result.isEmpty()) {
+                        currentParam.tokenLocation(loc);
+                    }
+                } else {
+                    if (token == Token.VALUE_STRING) {
+                        value = p.text();
+                        type = "keyword";
+                    } else if (token == Token.VALUE_NUMBER) {
+                        XContentParser.NumberType numberType = p.numberType();
+                        if (numberType == XContentParser.NumberType.INT) {
+                            value = p.intValue();
+                            type = "integer";
+                        } else if (numberType == XContentParser.NumberType.LONG) {
+                            value = p.longValue();
+                            type = "long";
+                        } else if (numberType == XContentParser.NumberType.FLOAT) {
+                            value = p.floatValue();
+                            type = "float";
+                        } else if (numberType == XContentParser.NumberType.DOUBLE) {
+                            value = p.doubleValue();
+                            type = "double";
+                        }
+                    } else if (token == Token.VALUE_BOOLEAN) {
+                        value = p.booleanValue();
+                        type = "boolean";
+                    } else if (token == Token.VALUE_NULL) {
+                        value = null;
+                        type = "null";
+                    } else {
+                        throw new XContentParseException(loc, "Failed to parse object: unexpected token [" + token + "] found");
+                    }
+
+                    currentParam = new SqlTypedParamValue(type, value, false);
+                    if ((previousParam != null && previousParam.hasExplicitType() == true) || result.isEmpty()) {
+                        currentParam.tokenLocation(loc);
+                    }
+                }
+
+                result.add(currentParam);
+                previousParam = currentParam;
+            }
+        }
+
+        return result;
+    }
+
+    protected static void validateParams(List<SqlTypedParamValue> params, Mode mode) {
+        for(SqlTypedParamValue param : params) {            
+            if (Mode.isDriver(mode) && param.hasExplicitType() == false) {
+                throw new XContentParseException(param.tokenLocation(), "[params] must be an array where each entry is an object with a "
+                        + "value/type pair");
+            }
+            if (Mode.isDriver(mode) == false && param.hasExplicitType() == true) {
+                throw new XContentParseException(param.tokenLocation(), "[params] must be an array where each entry is a single field (no "
+                        + "objects supported)");
+            }
+        }
+    }
 
     /**
      * The client's time zone
@@ -204,10 +291,11 @@ public AbstractSqlQueryRequest(StreamInput in) throws IOException {
     public static void writeSqlTypedParamValue(StreamOutput out, SqlTypedParamValue value) throws IOException {
         out.writeString(value.type);
         out.writeGenericValue(value.value);
+        out.writeBoolean(value.hasExplicitType());
     }
 
     public static SqlTypedParamValue readSqlTypedParamValue(StreamInput in) throws IOException {
-        return new SqlTypedParamValue(in.readString(), in.readGenericValue());
+        return new SqlTypedParamValue(in.readString(), in.readGenericValue(), in.readBoolean());
     }
 
     @Override
@@ -248,6 +336,6 @@ public boolean equals(Object o) {
 
     @Override
     public int hashCode() {
-        return Objects.hash(super.hashCode(), query, zoneId, fetchSize, requestTimeout, pageTimeout, filter);
+        return Objects.hash(super.hashCode(), query, params, zoneId, fetchSize, requestTimeout, pageTimeout, filter);
     }
 }

x-pack/plugin/sql/sql-action/src/main/java/org/elasticsearch/xpack/sql/action/SqlQueryRequest.java

@@ -188,6 +188,8 @@ public XContentBuilder toXContent(XContentBuilder builder, Params params) throws
     }
 
     public static SqlQueryRequest fromXContent(XContentParser parser) {
-        return PARSER.apply(parser, null);
+        SqlQueryRequest request = PARSER.apply(parser,  null);
+        validateParams(request.params(), request.mode());
+        return request;
     }
 }

x-pack/plugin/sql/sql-action/src/main/java/org/elasticsearch/xpack/sql/action/SqlTranslateRequest.java

@@ -58,6 +58,7 @@ public String getDescription() {
 
     public static SqlTranslateRequest fromXContent(XContentParser parser) {
         SqlTranslateRequest request = PARSER.apply(parser, null);
+        validateParams(request.params(), request.mode());
         return request;
     }