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Escape identifiers #99

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Escape identifiers #99

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28 changes: 23 additions & 5 deletions src/db/core.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -220,6 +220,21 @@ export function sql<
return new SQLFragment<RunResult, Constraint>(Array.prototype.slice.apply(literals), expressions);
}

export function escapeIdentifier (identifier: string | number): string {
return `"${String(identifier).replace(/"/g, '""')}"`;
}

export function unescapeIdentifier (escapedIdentifier: string): string {
if (escapedIdentifier.charAt(0) === '"') {
const innerEscapedIdentifier = escapedIdentifier.charAt(escapedIdentifier.length - 1) === '"'
? escapedIdentifier.slice(1, -1)
: escapedIdentifier.slice(1);
return innerEscapedIdentifier.replace(/""/g, '"');
} else {
return escapedIdentifier;
}
}

let preparedNameSeq = 0;

export class SQLFragment<RunResult = pg.QueryResult['rows'], Constraint = never> {
Expand Down Expand Up @@ -310,7 +325,10 @@ export class SQLFragment<RunResult = pg.QueryResult['rows'], Constraint = never>

} else if (typeof expression === 'string') {
// if it's a string, it should be a x.Table or x.Column type, so just needs quoting
result.text += expression.charAt(0) === '"' ? expression : `"${expression}"`;
// Re-escape identifier even if it "seems" to be already escaped. A malicious user
// could pass a string that starts with " but injects SQL code. Only trust escaped
// identifiers that we escape ourselves.
result.text += escapeIdentifier(unescapeIdentifier(expression));

} else if (expression instanceof DangerousRawString) {
// Little Bobby Tables passes straight through ...
Expand Down Expand Up @@ -351,19 +369,19 @@ export class SQLFragment<RunResult = pg.QueryResult['rows'], Constraint = never>
} else if (expression === self) {
// alias to the latest column, if applicable
if (!currentColumn) throw new Error(`The 'self' column alias has no meaning here`);
result.text += `"${currentColumn}"`;
result.text += escapeIdentifier(currentColumn);

} else if (expression instanceof ParentColumn) {
// alias to the parent table (plus supplied column name) of a nested query, if applicable
if (!parentTable) throw new Error(`The 'parent' table alias has no meaning here`);
result.text += `"${parentTable}"."${expression.value}"`;
result.text += `${escapeIdentifier(parentTable)}.${escapeIdentifier(expression.value)}`;

} else if (expression instanceof ColumnNames) {
// a ColumnNames-wrapped object -> quoted names in a repeatable order
// OR a ColumnNames-wrapped array -> quoted array values
const columnNames = Array.isArray(expression.value) ? expression.value :
Object.keys(expression.value).sort();
result.text += columnNames.map(k => `"${k}"`).join(', ');
result.text += columnNames.map(k => escapeIdentifier(k)).join(', ');

} else if (expression instanceof ColumnValues) {
// a ColumnValues-wrapped object OR array
Expand Down Expand Up @@ -412,7 +430,7 @@ export class SQLFragment<RunResult = pg.QueryResult['rows'], Constraint = never>
result.text += ')';

} else {
result.text += `"${columnName}" = `;
result.text += `${escapeIdentifier(columnName)} = `;
this.compileExpression(columnValue instanceof ParentColumn ? columnValue : new Parameter(columnValue),
result, parentTable, columnName);
}
Expand Down