Source release 19.1.0

third_party/libcppbor/src/cppbor_parse.cpp

@@ -0,0 +1,380 @@
+/*
+ * Copyright 2019 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "cppbor_parse.h"
+
+#include <limits>
+#include <sstream>
+#include <stack>
+
+#ifndef __has_feature
+  #define __has_feature(x) 0
+#endif
+
+namespace cppbor {
+
+namespace {
+
+std::string insufficientLengthString(size_t bytesNeeded, size_t bytesAvail,
+                                     const std::string& type) {
+    char buf[1024];
+    snprintf(buf, sizeof(buf), "Need %zu byte(s) for %s, have %zu.", bytesNeeded, type.c_str(),
+             bytesAvail);
+    return std::string(buf);
+}
+
+template <typename T, typename = std::enable_if_t<std::is_unsigned<T>::value>>
+std::tuple<bool, uint64_t, const uint8_t*> parseLength(const uint8_t* pos, const uint8_t* end,
+                                                       ParseClient* parseClient) {
+    if (pos + sizeof(T) > end) {
+        parseClient->error(pos - 1, insufficientLengthString(sizeof(T), end - pos, "length field"));
+        return {false, 0, pos};
+    }
+
+    const uint8_t* intEnd = pos + sizeof(T);
+    T result = 0;
+    do {
+        result = static_cast<T>((result << 8) | *pos++);
+    } while (pos < intEnd);
+    return {true, result, pos};
+}
+
+std::tuple<const uint8_t*, ParseClient*> parseRecursively(const uint8_t* begin, const uint8_t* end,
+                                                          bool emitViews, ParseClient* parseClient);
+
+std::tuple<const uint8_t*, ParseClient*> handleUint(uint64_t value, const uint8_t* hdrBegin,
+                                                    const uint8_t* hdrEnd,
+                                                    ParseClient* parseClient) {
+    std::unique_ptr<Item> item = std::make_unique<Uint>(value);
+    return {hdrEnd,
+            parseClient->item(item, hdrBegin, hdrEnd /* valueBegin */, hdrEnd /* itemEnd */)};
+}
+
+std::tuple<const uint8_t*, ParseClient*> handleNint(uint64_t value, const uint8_t* hdrBegin,
+                                                    const uint8_t* hdrEnd,
+                                                    ParseClient* parseClient) {
+    if (value > std::numeric_limits<int64_t>::max()) {
+        parseClient->error(hdrBegin, "NINT values that don't fit in int64_t are not supported.");
+        return {hdrBegin, nullptr /* end parsing */};
+    }
+    std::unique_ptr<Item> item = std::make_unique<Nint>(-1 - static_cast<int64_t>(value));
+    return {hdrEnd,
+            parseClient->item(item, hdrBegin, hdrEnd /* valueBegin */, hdrEnd /* itemEnd */)};
+}
+
+std::tuple<const uint8_t*, ParseClient*> handleBool(uint64_t value, const uint8_t* hdrBegin,
+                                                    const uint8_t* hdrEnd,
+                                                    ParseClient* parseClient) {
+    std::unique_ptr<Item> item = std::make_unique<Bool>(value == TRUE);
+    return {hdrEnd,
+            parseClient->item(item, hdrBegin, hdrEnd /* valueBegin */, hdrEnd /* itemEnd */)};
+}
+
+std::tuple<const uint8_t*, ParseClient*> handleNull(const uint8_t* hdrBegin, const uint8_t* hdrEnd,
+                                                    ParseClient* parseClient) {
+    std::unique_ptr<Item> item = std::make_unique<Null>();
+    return {hdrEnd,
+            parseClient->item(item, hdrBegin, hdrEnd /* valueBegin */, hdrEnd /* itemEnd */)};
+}
+
+template <typename T>
+std::tuple<const uint8_t*, ParseClient*> handleString(uint64_t length, const uint8_t* hdrBegin,
+                                                      const uint8_t* valueBegin, const uint8_t* end,
+                                                      const std::string& errLabel,
+                                                      ParseClient* parseClient) {
+    ssize_t signed_length = static_cast<ssize_t>(length);
+    if (end - valueBegin < signed_length || signed_length < 0) {
+        parseClient->error(hdrBegin, insufficientLengthString(length, end - valueBegin, errLabel));
+        return {hdrBegin, nullptr /* end parsing */};
+    }
+
+    std::unique_ptr<Item> item = std::make_unique<T>(valueBegin, valueBegin + length);
+    return {valueBegin + length,
+            parseClient->item(item, hdrBegin, valueBegin, valueBegin + length)};
+}
+
+class IncompleteItem {
+  public:
+    virtual ~IncompleteItem() {}
+    virtual void add(std::unique_ptr<Item> item) = 0;
+};
+
+class IncompleteArray : public Array, public IncompleteItem {
+  public:
+    explicit IncompleteArray(size_t size) : mSize(size) {}
+
+    // We return the "complete" size, rather than the actual size.
+    size_t size() const override { return mSize; }
+
+    void add(std::unique_ptr<Item> item) override {
+        mEntries.reserve(mSize);
+        mEntries.push_back(std::move(item));
+    }
+
+  private:
+    size_t mSize;
+};
+
+class IncompleteMap : public Map, public IncompleteItem {
+  public:
+    explicit IncompleteMap(size_t size) : mSize(size) {}
+
+    // We return the "complete" size, rather than the actual size.
+    size_t size() const override { return mSize; }
+
+    void add(std::unique_ptr<Item> item) override {
+        if (mKeyHeldForAdding) {
+            mEntries.reserve(mSize);
+            mEntries.push_back({std::move(mKeyHeldForAdding), std::move(item)});
+        } else {
+            mKeyHeldForAdding = std::move(item);
+        }
+    }
+
+  private:
+    std::unique_ptr<Item> mKeyHeldForAdding;
+    size_t mSize;
+};
+
+class IncompleteSemanticTag : public SemanticTag, public IncompleteItem {
+  public:
+    explicit IncompleteSemanticTag(uint64_t value) : SemanticTag(value) {}
+
+    // We return the "complete" size, rather than the actual size.
+    size_t size() const override { return 1; }
+
+    void add(std::unique_ptr<Item> item) override { mTaggedItem = std::move(item); }
+};
+
+std::tuple<const uint8_t*, ParseClient*> handleEntries(size_t entryCount, const uint8_t* hdrBegin,
+                                                       const uint8_t* pos, const uint8_t* end,
+                                                       const std::string& typeName,
+                                                       bool emitViews,
+                                                       ParseClient* parseClient) {
+    while (entryCount > 0) {
+        --entryCount;
+        if (pos == end) {
+            parseClient->error(hdrBegin, "Not enough entries for " + typeName + ".");
+            return {hdrBegin, nullptr /* end parsing */};
+        }
+        std::tie(pos, parseClient) = parseRecursively(pos, end, emitViews, parseClient);
+        if (!parseClient) return {hdrBegin, nullptr};
+    }
+    return {pos, parseClient};
+}
+
+std::tuple<const uint8_t*, ParseClient*> handleCompound(
+        std::unique_ptr<Item> item, uint64_t entryCount, const uint8_t* hdrBegin,
+        const uint8_t* valueBegin, const uint8_t* end, const std::string& typeName,
+        bool emitViews, ParseClient* parseClient) {
+    parseClient =
+            parseClient->item(item, hdrBegin, valueBegin, valueBegin /* don't know the end yet */);
+    if (!parseClient) return {hdrBegin, nullptr};
+
+    const uint8_t* pos;
+    std::tie(pos, parseClient) =
+            handleEntries(entryCount, hdrBegin, valueBegin, end, typeName, emitViews, parseClient);
+    if (!parseClient) return {hdrBegin, nullptr};
+
+    return {pos, parseClient->itemEnd(item, hdrBegin, valueBegin, pos)};
+}
+
+std::tuple<const uint8_t*, ParseClient*> parseRecursively(const uint8_t* begin, const uint8_t* end,
+                                                          bool emitViews, ParseClient* parseClient) {
+    if (begin == end) {
+        parseClient->error(
+                begin,
+                "Input buffer is empty. Begin and end cannot point to the same location.");
+        return {begin, nullptr};
+    }
+
+    const uint8_t* pos = begin;
+
+    MajorType type = static_cast<MajorType>(*pos & 0xE0);
+    uint8_t tagInt = *pos & 0x1F;
+    ++pos;
+
+    bool success = true;
+    uint64_t addlData;
+    if (tagInt < ONE_BYTE_LENGTH) {
+        addlData = tagInt;
+    } else if (tagInt > EIGHT_BYTE_LENGTH) {
+        parseClient->error(
+                begin,
+                "Reserved additional information value or unsupported indefinite length item.");
+        return {begin, nullptr};
+    } else {
+        switch (tagInt) {
+            case ONE_BYTE_LENGTH:
+                std::tie(success, addlData, pos) = parseLength<uint8_t>(pos, end, parseClient);
+                break;
+
+            case TWO_BYTE_LENGTH:
+                std::tie(success, addlData, pos) = parseLength<uint16_t>(pos, end, parseClient);
+                break;
+
+            case FOUR_BYTE_LENGTH:
+                std::tie(success, addlData, pos) = parseLength<uint32_t>(pos, end, parseClient);
+                break;
+
+            case EIGHT_BYTE_LENGTH:
+                std::tie(success, addlData, pos) = parseLength<uint64_t>(pos, end, parseClient);
+                break;
+
+            default:
+                //  It's impossible to get here
+                parseClient->error(begin, "Invalid tag.");
+                return {};
+        }
+    }
+
+    if (!success) return {begin, nullptr};
+
+    switch (type) {
+        case UINT:
+            return handleUint(addlData, begin, pos, parseClient);
+
+        case NINT:
+            return handleNint(addlData, begin, pos, parseClient);
+
+        case BSTR:
+            return handleString<Bstr>(addlData, begin, pos, end, "byte string", parseClient);
+
+        case TSTR:
+            return handleString<Tstr>(addlData, begin, pos, end, "text string", parseClient);
+
+        case ARRAY:
+            return handleCompound(std::make_unique<IncompleteArray>(addlData), addlData, begin, pos,
+                                  end, "array", emitViews, parseClient);
+
+        case MAP:
+            return handleCompound(std::make_unique<IncompleteMap>(addlData), addlData * 2, begin,
+                                  pos, end, "map", emitViews, parseClient);
+
+        case SEMANTIC:
+            return handleCompound(std::make_unique<IncompleteSemanticTag>(addlData), 1, begin, pos,
+                                  end, "semantic", emitViews, parseClient);
+
+        case SIMPLE:
+            switch (addlData) {
+                case TRUE:
+                case FALSE:
+                    return handleBool(addlData, begin, pos, parseClient);
+                case NULL_V:
+                    return handleNull(begin, pos, parseClient);
+                default:
+                    parseClient->error(begin, "Unsupported floating-point or simple value.");
+                    return {begin, nullptr};
+            }
+    }
+    // Impossible to get here.
+    parseClient->error(begin, "Invalid type.");
+    return {};
+}
+
+class FullParseClient : public ParseClient {
+  public:
+    virtual ParseClient* item(std::unique_ptr<Item>& item, const uint8_t*, const uint8_t*,
+                              const uint8_t* end) override {
+        if (mParentStack.empty() && !item->isCompound()) {
+            // This is the first and only item.
+            mTheItem = std::move(item);
+            mPosition = end;
+            return nullptr;  //  We're done.
+        }
+
+        if (item->isCompound()) {
+            // Starting a new compound data item, i.e. a new parent.  Save it on the parent stack.
+            // It's safe to save a raw pointer because the unique_ptr is guaranteed to stay in
+            // existence until the corresponding itemEnd() call.
+            mParentStack.push(item.get());
+            return this;
+        } else {
+            appendToLastParent(std::move(item));
+            return this;
+        }
+    }
+
+    virtual ParseClient* itemEnd(std::unique_ptr<Item>& item, const uint8_t*, const uint8_t*,
+                                 const uint8_t* end) override {
+        if (!item->isCompound() || item.get() != mParentStack.top()) {
+          return nullptr;
+        }
+        mParentStack.pop();
+
+        if (mParentStack.empty()) {
+            mTheItem = std::move(item);
+            mPosition = end;
+            return nullptr;  // We're done
+        } else {
+            appendToLastParent(std::move(item));
+            return this;
+        }
+    }
+
+    virtual void error(const uint8_t* position, const std::string& errorMessage) override {
+        mPosition = position;
+        mErrorMessage = errorMessage;
+    }
+
+    std::tuple<std::unique_ptr<Item> /* result */, const uint8_t* /* newPos */,
+               std::string /* errMsg */>
+    parseResult() {
+        std::unique_ptr<Item> p = std::move(mTheItem);
+        return {std::move(p), mPosition, std::move(mErrorMessage)};
+    }
+
+  private:
+    void appendToLastParent(std::unique_ptr<Item> item) {
+        auto parent = mParentStack.top();
+#if __has_feature(cxx_rtti)
+        assert(dynamic_cast<IncompleteItem*>(parent));
+#endif
+
+        IncompleteItem* parentItem{};
+        if (parent->type() == ARRAY) {
+            parentItem = static_cast<IncompleteArray*>(parent);
+        } else if (parent->type() == MAP) {
+            parentItem = static_cast<IncompleteMap*>(parent);
+        } else if (parent->asSemanticTag()) {
+            parentItem = static_cast<IncompleteSemanticTag*>(parent);
+        } else {
+            // Impossible to get here.
+        }
+        parentItem->add(std::move(item));
+    }
+
+    std::unique_ptr<Item> mTheItem;
+    std::stack<Item*> mParentStack;
+    const uint8_t* mPosition = nullptr;
+    std::string mErrorMessage;
+};
+
+}  // anonymous namespace
+
+void parse(const uint8_t* begin, const uint8_t* end, ParseClient* parseClient) {
+    parseRecursively(begin, end, false, parseClient);
+}
+
+std::tuple<std::unique_ptr<Item> /* result */, const uint8_t* /* newPos */,
+           std::string /* errMsg */>
+parse(const uint8_t* begin, const uint8_t* end) {
+    FullParseClient parseClient;
+    parse(begin, end, &parseClient);
+    return parseClient.parseResult();
+}
+
+}  // namespace cppbor