aboutsummaryrefslogtreecommitdiffstats
path: root/libsolidity/analysis/StaticAnalyzer.cpp
blob: 323282ca2c5fd193b1ed5c663bc366c57b57128d (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
/*
    This file is part of solidity.

    solidity is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    solidity is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with solidity.  If not, see <http://www.gnu.org/licenses/>.
*/
/**
 * @author Federico Bond <federicobond@gmail.com>
 * @date 2016
 * Static analyzer and checker.
 */

#include <libsolidity/analysis/StaticAnalyzer.h>
#include <libsolidity/analysis/ConstantEvaluator.h>
#include <libsolidity/ast/AST.h>
#include <libsolidity/interface/ErrorReporter.h>
#include <memory>

using namespace std;
using namespace dev;
using namespace dev::solidity;

bool StaticAnalyzer::analyze(SourceUnit const& _sourceUnit)
{
    _sourceUnit.accept(*this);
    return Error::containsOnlyWarnings(m_errorReporter.errors());
}

bool StaticAnalyzer::visit(ContractDefinition const& _contract)
{
    m_library = _contract.isLibrary();
    m_currentContract = &_contract;
    return true;
}

void StaticAnalyzer::endVisit(ContractDefinition const&)
{
    m_library = false;
    m_currentContract = nullptr;
}

bool StaticAnalyzer::visit(FunctionDefinition const& _function)
{
    const bool isInterface = m_currentContract->contractKind() == ContractDefinition::ContractKind::Interface;

    if (_function.noVisibilitySpecified())
        m_errorReporter.warning(
            _function.location(),
            "No visibility specified. Defaulting to \"" +
            Declaration::visibilityToString(_function.visibility()) +
            "\"." +
            (isInterface ? " In interfaces it defaults to external." : "")
        );
    if (_function.isImplemented())
        m_currentFunction = &_function;
    else
        solAssert(!m_currentFunction, "");
    solAssert(m_localVarUseCount.empty(), "");
    m_nonPayablePublic = _function.isPublic() && !_function.isPayable();
    m_constructor = _function.isConstructor();
    return true;
}

void StaticAnalyzer::endVisit(FunctionDefinition const&)
{
    m_currentFunction = nullptr;
    m_nonPayablePublic = false;
    m_constructor = false;
    for (auto const& var: m_localVarUseCount)
        if (var.second == 0)
        {
            if (var.first.second->isCallableParameter())
                m_errorReporter.warning(
                    var.first.second->location(),
                    "Unused function parameter. Remove or comment out the variable name to silence this warning."
                );
            else
                m_errorReporter.warning(var.first.second->location(), "Unused local variable.");
        }

    m_localVarUseCount.clear();
}

bool StaticAnalyzer::visit(Identifier const& _identifier)
{
    if (m_currentFunction)
        if (auto var = dynamic_cast<VariableDeclaration const*>(_identifier.annotation().referencedDeclaration))
        {
            solAssert(!var->name().empty(), "");
            if (var->isLocalVariable())
                m_localVarUseCount[make_pair(var->id(), var)] += 1;
        }
    return true;
}

bool StaticAnalyzer::visit(VariableDeclaration const& _variable)
{
    if (m_currentFunction)
    {
        solAssert(_variable.isLocalVariable(), "");
        if (_variable.name() != "")
            // This is not a no-op, the entry might pre-exist.
            m_localVarUseCount[make_pair(_variable.id(), &_variable)] += 0;
    }
    else if (_variable.isStateVariable())
    {
        set<StructDefinition const*> structsSeen;
        if (structureSizeEstimate(*_variable.type(), structsSeen) >= bigint(1) << 64)
            m_errorReporter.warning(
                _variable.location(),
                "Variable covers a large part of storage and thus makes collisions likely. "
                "Either use mappings or dynamic arrays and allow their size to be increased only "
                "in small quantities per transaction."
            );
    }
    return true;
}

bool StaticAnalyzer::visit(Return const& _return)
{
    // If the return has an expression, it counts as
    // a "use" of the return parameters.
    if (m_currentFunction && _return.expression())
        for (auto const& var: m_currentFunction->returnParameters())
            if (!var->name().empty())
                m_localVarUseCount[make_pair(var->id(), var.get())] += 1;
    return true;
}

bool StaticAnalyzer::visit(ExpressionStatement const& _statement)
{
    if (_statement.expression().annotation().isPure)
        m_errorReporter.warning(
            _statement.location(),
            "Statement has no effect."
        );

    return true;
}

bool StaticAnalyzer::visit(MemberAccess const& _memberAccess)
{
    if (MagicType const* type = dynamic_cast<MagicType const*>(_memberAccess.expression().annotation().type.get()))
    {
        if (type->kind() == MagicType::Kind::Message && _memberAccess.memberName() == "gas")
            m_errorReporter.typeError(
                _memberAccess.location(),
                "\"msg.gas\" has been deprecated in favor of \"gasleft()\""
            );
        else if (type->kind() == MagicType::Kind::Block && _memberAccess.memberName() == "blockhash")
            m_errorReporter.typeError(
                _memberAccess.location(),
                "\"block.blockhash()\" has been deprecated in favor of \"blockhash()\""
            );
    }

    if (m_nonPayablePublic && !m_library)
        if (MagicType const* type = dynamic_cast<MagicType const*>(_memberAccess.expression().annotation().type.get()))
            if (type->kind() == MagicType::Kind::Message && _memberAccess.memberName() == "value")
                m_errorReporter.warning(
                    _memberAccess.location(),
                    "\"msg.value\" used in non-payable function. Do you want to add the \"payable\" modifier to this function?"
                );

    if (_memberAccess.memberName() == "callcode")
        if (auto const* type = dynamic_cast<FunctionType const*>(_memberAccess.annotation().type.get()))
            if (type->kind() == FunctionType::Kind::BareCallCode)
                m_errorReporter.typeError(
                    _memberAccess.location(),
                    "\"callcode\" has been deprecated in favour of \"delegatecall\"."
                );

    if (m_constructor)
    {
        auto const* expr = &_memberAccess.expression();
        while(expr)
        {
            if (auto id = dynamic_cast<Identifier const*>(expr))
            {
                if (id->name() == "this")
                    m_errorReporter.warning(
                        id->location(),
                        "\"this\" used in constructor. "
                        "Note that external functions of a contract "
                        "cannot be called while it is being constructed.");
                break;
            }
            else if (auto tuple = dynamic_cast<TupleExpression const*>(expr))
            {
                if (tuple->components().size() == 1)
                    expr = tuple->components().front().get();
                else
                    break;
            }
            else
                break;
        }
    }

    return true;
}

bool StaticAnalyzer::visit(InlineAssembly const& _inlineAssembly)
{
    if (!m_currentFunction)
        return true;

    for (auto const& ref: _inlineAssembly.annotation().externalReferences)
    {
        if (auto var = dynamic_cast<VariableDeclaration const*>(ref.second.declaration))
        {
            solAssert(!var->name().empty(), "");
            if (var->isLocalVariable())
                m_localVarUseCount[make_pair(var->id(), var)] += 1;
        }
    }

    return true;
}

bool StaticAnalyzer::visit(BinaryOperation const& _operation)
{
    if (
        _operation.rightExpression().annotation().isPure &&
        (_operation.getOperator() == Token::Div || _operation.getOperator() == Token::Mod)
    )
        if (auto rhs = dynamic_pointer_cast<RationalNumberType const>(
            ConstantEvaluator(m_errorReporter).evaluate(_operation.rightExpression())
        ))
            if (rhs->isZero())
                m_errorReporter.typeError(
                    _operation.location(),
                    (_operation.getOperator() == Token::Div) ? "Division by zero." : "Modulo zero."
                );

    return true;
}

bool StaticAnalyzer::visit(FunctionCall const& _functionCall)
{
    if (_functionCall.annotation().kind == FunctionCallKind::FunctionCall)
    {
        auto functionType = dynamic_pointer_cast<FunctionType const>(_functionCall.expression().annotation().type);
        solAssert(functionType, "");
        if (functionType->kind() == FunctionType::Kind::AddMod || functionType->kind() == FunctionType::Kind::MulMod)
        {
            solAssert(_functionCall.arguments().size() == 3, "");
            if (_functionCall.arguments()[2]->annotation().isPure)
                if (auto lastArg = dynamic_pointer_cast<RationalNumberType const>(
                    ConstantEvaluator(m_errorReporter).evaluate(*(_functionCall.arguments())[2])
                ))
                    if (lastArg->isZero())
                        m_errorReporter.typeError(
                            _functionCall.location(),
                            "Arithmetic modulo zero."
                        );
        }
    }
    return true;
}

bigint StaticAnalyzer::structureSizeEstimate(Type const& _type, set<StructDefinition const*>& _structsSeen)
{
    switch (_type.category())
    {
    case Type::Category::Array:
    {
        auto const& t = dynamic_cast<ArrayType const&>(_type);
        return structureSizeEstimate(*t.baseType(), _structsSeen) * (t.isDynamicallySized() ? 1 : t.length());
    }
    case Type::Category::Struct:
    {
        auto const& t = dynamic_cast<StructType const&>(_type);
        bigint size = 1;
        if (!_structsSeen.count(&t.structDefinition()))
        {
            _structsSeen.insert(&t.structDefinition());
            for (auto const& m: t.members(nullptr))
                size += structureSizeEstimate(*m.type, _structsSeen);
        }
        return size;
    }
    case Type::Category::Mapping:
    {
        return structureSizeEstimate(*dynamic_cast<MappingType const&>(_type).valueType(), _structsSeen);
    }
    default:
        break;
    }
    return bigint(1);
}