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Изменения, которые будут включены в коммит:
	новый файл:    README.md
	новый файл:    json11.cpp
	новый файл:    json11.hpp
	новый файл:    udpserver.cpp

README.md

@@ -0,0 +1,18 @@
+# Simple multithreaded UDP server
+
+Simple multithreaded UDP server.  
+The number of threads is determined by the number of CPU cores.
+
+## Getting Started
+
+>make
+
+>./udpserver 127.0.0.1 10003
+
+## Testing
+
+>ncat -u 127.0.0.1 10003
+
+## License
+
+This project is licensed under the GNU GPLv3 License - see the [LICENSE](LICENSE) file for details.

json11.cpp

@@ -0,0 +1,931 @@
+/* Copyright (c) 2013 Dropbox, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "json11.hpp"
+#include <cassert>
+#include <cmath>
+#include <cstdlib>
+#include <cstdio>
+#include <limits>
+
+namespace json11 {
+static const int max_depth = 200;
+
+using std::string;
+using std::vector;
+using std::map;
+using std::make_shared;
+using std::initializer_list;
+using std::move;
+
+/* Helper for representing null - just a do-nothing struct, plus comparison
+ * operators so the helpers in JsonValue work. We can't use nullptr_t because
+ * it may not be orderable.
+ */
+struct NullStruct {
+    bool operator==(NullStruct) const {
+        return true;
+    }
+
+    bool operator<(NullStruct) const {
+        return false;
+    }
+};
+
+/* * * * * * * * * * * * * * * * * * * *
+ * Serialization
+ */
+
+static void dump(NullStruct, string &out) {
+    out += "null";
+}
+
+static void dump(double value, string &out) {
+    if (std::isfinite(value)) {
+        char buf[32];
+        snprintf(buf, sizeof buf, "%.17g", value);
+        out += buf;
+    } else {
+        out += "null";
+    }
+}
+
+static void dump(int value, string &out) {
+    char buf[32];
+
+    snprintf(buf, sizeof buf, "%d", value);
+    out += buf;
+}
+
+static void dump(bool value, string &out) {
+    out += value ? "true" : "false";
+}
+
+static void dump(const string &value, string &out) {
+    out += '"';
+
+    for (size_t i = 0; i < value.length(); i++) {
+        const char ch = value[i];
+
+        if (ch == '\\') {
+            out += "\\\\";
+        } else if (ch == '"') {
+            out += "\\\"";
+        } else if (ch == '\b') {
+            out += "\\b";
+        } else if (ch == '\f') {
+            out += "\\f";
+        } else if (ch == '\n') {
+            out += "\\n";
+        } else if (ch == '\r') {
+            out += "\\r";
+        } else if (ch == '\t') {
+            out += "\\t";
+        } else if (static_cast<uint8_t>(ch) <= 0x1f) {
+            char buf[8];
+            snprintf(buf, sizeof buf, "\\u%04x", ch);
+            out += buf;
+        } else if (static_cast<uint8_t>(ch) == 0xe2 && static_cast<uint8_t>(value[i + 1]) == 0x80
+                   && static_cast<uint8_t>(value[i + 2]) == 0xa8) {
+            out += "\\u2028";
+            i += 2;
+        } else if (static_cast<uint8_t>(ch) == 0xe2 && static_cast<uint8_t>(value[i + 1]) == 0x80
+                   && static_cast<uint8_t>(value[i + 2]) == 0xa9) {
+            out += "\\u2029";
+            i += 2;
+        } else {
+            out += ch;
+        }
+    }
+
+    out += '"';
+}
+
+static void dump(const Json::array &values, string &out) {
+    bool first = true;
+
+    out += "[";
+
+    for (const auto &value : values) {
+        if (!first) out += ", ";
+
+        value.dump(out);
+        first = false;
+    }
+
+    out += "]";
+}
+
+static void dump(const Json::object &values, string &out) {
+    bool first = true;
+
+    out += "{";
+
+    for (const auto &kv : values) {
+        if (!first) out += ", ";
+
+        dump(kv.first, out);
+        out += ": ";
+        kv.second.dump(out);
+        first = false;
+    }
+
+    out += "}";
+}
+
+void Json::dump(string &out) const {
+    m_ptr->dump(out);
+}
+
+/* * * * * * * * * * * * * * * * * * * *
+ * Value wrappers
+ */
+
+template <Json::Type tag, typename T>
+class Value : public JsonValue {
+protected:
+
+// Constructors
+explicit Value(const T &value) : m_value(value) {
+}
+
+explicit Value(T &&value)      : m_value(move(value)) {
+}
+
+// Get type tag
+Json::Type type() const override {
+    return tag;
+}
+
+// Comparisons
+bool equals(const JsonValue *other) const override {
+    return m_value == static_cast<const Value<tag, T> *>(other)->m_value;
+}
+
+bool less(const JsonValue *other) const override {
+    return m_value < static_cast<const Value<tag, T> *>(other)->m_value;
+}
+
+const T m_value;
+void dump(string &out) const override {
+    json11::dump(m_value, out);
+}
+};
+
+class JsonDouble final : public Value<Json::NUMBER, double> {
+double number_value() const override {
+    return m_value;
+}
+
+int int_value() const override {
+    return static_cast<int>(m_value);
+}
+
+bool equals(const JsonValue *other) const override {
+    return m_value == other->number_value();
+}
+
+bool less(const JsonValue *other)   const override {
+    return m_value <  other->number_value();
+}
+
+public:
+explicit JsonDouble(double value) : Value(value) {
+}
+};
+
+class JsonInt final : public Value<Json::NUMBER, int> {
+double number_value() const override {
+    return m_value;
+}
+
+int int_value() const override {
+    return m_value;
+}
+
+bool equals(const JsonValue *other) const override {
+    return m_value == other->number_value();
+}
+
+bool less(const JsonValue *other)   const override {
+    return m_value <  other->number_value();
+}
+
+public:
+explicit JsonInt(int value) : Value(value) {
+}
+};
+
+class JsonBoolean final : public Value<Json::BOOL, bool> {
+bool bool_value() const override {
+    return m_value;
+}
+
+public:
+explicit JsonBoolean(bool value) : Value(value) {
+}
+};
+
+class JsonString final : public Value<Json::STRING, string> {
+const string &string_value() const override {
+    return m_value;
+}
+
+public:
+explicit JsonString(const string &value) : Value(value) {
+}
+
+explicit JsonString(string &&value)      : Value(move(value)) {
+}
+};
+
+class JsonArray final : public Value<Json::ARRAY, Json::array> {
+const Json::array &array_items() const override {
+    return m_value;
+}
+
+const Json & operator[](size_t i) const override;
+public:
+explicit JsonArray(const Json::array &value) : Value(value) {
+}
+
+explicit JsonArray(Json::array &&value)      : Value(move(value)) {
+}
+};
+
+class JsonObject final : public Value<Json::OBJECT, Json::object> {
+const Json::object &object_items() const override {
+    return m_value;
+}
+
+const Json & operator[](const string &key) const override;
+public:
+explicit JsonObject(const Json::object &value) : Value(value) {
+}
+
+explicit JsonObject(Json::object &&value)      : Value(move(value)) {
+}
+};
+
+class JsonNull final : public Value<Json::NUL, NullStruct> {
+public:
+JsonNull() : Value({
+        }) {}
+};
+
+/* * * * * * * * * * * * * * * * * * * *
+ * Static globals - static-init-safe
+ */
+struct Statics {
+    const std::shared_ptr<JsonValue> null = make_shared<JsonNull>();
+    const std::shared_ptr<JsonValue> t = make_shared<JsonBoolean>(true);
+    const std::shared_ptr<JsonValue> f = make_shared<JsonBoolean>(false);
+    const string empty_string;
+    const vector<Json> empty_vector;
+    const map<string, Json> empty_map;
+    Statics() {
+    }
+};
+
+static const Statics & statics() {
+    static const Statics s {};
+
+    return s;
+}
+
+static const Json & static_null() {
+    // This has to be separate, not in Statics, because Json() accesses statics().null.
+    static const Json json_null;
+
+    return json_null;
+}
+
+/* * * * * * * * * * * * * * * * * * * *
+ * Constructors
+ */
+
+Json::Json() noexcept                  : m_ptr(statics().null) {
+}
+
+Json::Json(std::nullptr_t) noexcept    : m_ptr(statics().null) {
+}
+
+Json::Json(double value)               : m_ptr(make_shared<JsonDouble>(value)) {
+}
+
+Json::Json(int value)                  : m_ptr(make_shared<JsonInt>(value)) {
+}
+
+Json::Json(bool value)                 : m_ptr(value ? statics().t : statics().f) {
+}
+
+Json::Json(const string &value)        : m_ptr(make_shared<JsonString>(value)) {
+}
+
+Json::Json(string &&value)             : m_ptr(make_shared<JsonString>(move(value))) {
+}
+
+Json::Json(const char *value)         : m_ptr(make_shared<JsonString>(value)) {
+}
+
+Json::Json(const Json::array &values)  : m_ptr(make_shared<JsonArray>(values)) {
+}
+
+Json::Json(Json::array &&values)       : m_ptr(make_shared<JsonArray>(move(values))) {
+}
+
+Json::Json(const Json::object &values) : m_ptr(make_shared<JsonObject>(values)) {
+}
+
+Json::Json(Json::object &&values)      : m_ptr(make_shared<JsonObject>(move(values))) {
+}
+
+/* * * * * * * * * * * * * * * * * * * *
+ * Accessors
+ */
+
+Json::Type Json::type()                           const {
+    return m_ptr->type();
+}
+
+double Json::number_value()                       const {
+    return m_ptr->number_value();
+}
+
+int Json::int_value()                             const {
+    return m_ptr->int_value();
+}
+
+bool Json::bool_value()                           const {
+    return m_ptr->bool_value();
+}
+
+const string & Json::string_value()               const {
+    return m_ptr->string_value();
+}
+
+const vector<Json> & Json::array_items()          const {
+    return m_ptr->array_items();
+}
+
+const map<string, Json> & Json::object_items()    const {
+    return m_ptr->object_items();
+}
+
+const Json & Json::operator[](size_t i)          const {
+    return (*m_ptr)[i];
+}
+
+const Json & Json::operator[](const string &key) const {
+    return (*m_ptr)[key];
+}
+
+double JsonValue::number_value()              const {
+    return 0;
+}
+
+int JsonValue::int_value()                 const {
+    return 0;
+}
+
+bool JsonValue::bool_value()                const {
+    return false;
+}
+
+const string &            JsonValue::string_value()              const {
+    return statics().empty_string;
+}
+
+const vector<Json> &      JsonValue::array_items()               const {
+    return statics().empty_vector;
+}
+
+const map<string, Json> & JsonValue::object_items()              const {
+    return statics().empty_map;
+}
+
+const Json &              JsonValue::operator[](size_t)         const {
+    return static_null();
+}
+
+const Json &              JsonValue::operator[](const string &) const {
+    return static_null();
+}
+
+const Json & JsonObject::operator[](const string &key) const {
+    auto iter = m_value.find(key);
+
+    return (iter == m_value.end()) ? static_null() : iter->second;
+}
+
+const Json & JsonArray::operator[](size_t i) const {
+    if (i >= m_value.size()) return static_null();
+    else return m_value[i];
+}
+
+/* * * * * * * * * * * * * * * * * * * *
+ * Comparison
+ */
+
+bool Json::operator==(const Json &other) const {
+    if (m_ptr == other.m_ptr) return true;
+
+    if (m_ptr->type() != other.m_ptr->type()) return false;
+
+    return m_ptr->equals(other.m_ptr.get());
+}
+
+bool Json::operator<(const Json &other) const {
+    if (m_ptr == other.m_ptr) return false;
+
+    if (m_ptr->type() != other.m_ptr->type()) return m_ptr->type() < other.m_ptr->type();
+
+    return m_ptr->less(other.m_ptr.get());
+}
+
+/* * * * * * * * * * * * * * * * * * * *
+ * Parsing
+ */
+
+/* esc(c)
+ *
+ * Format char c suitable for printing in an error message.
+ */
+static inline string esc(char c) {
+    char buf[12];
+
+    if (static_cast<uint8_t>(c) >= 0x20 && static_cast<uint8_t>(c) <= 0x7f) {
+        snprintf(buf, sizeof buf, "'%c' (%d)", c, c);
+    } else {
+        snprintf(buf, sizeof buf, "(%d)", c);
+    }
+
+    return string(buf);
+}
+
+static inline bool in_range(long x, long lower, long upper) {
+    return (x >= lower && x <= upper);
+}
+
+namespace {
+/* JsonParser
+ *
+ * Object that tracks all state of an in-progress parse.
+ */
+struct JsonParser final {
+    /* State
+     */
+    const string &str;
+    size_t i;
+    string &err;
+    bool failed;
+    const JsonParse strategy;
+
+    /* fail(msg, err_ret = Json())
+     *
+     * Mark this parse as failed.
+     */
+    Json fail(string &&msg) {
+        return fail(move(msg), Json());
+    }
+
+    template <typename T>
+    T fail(string &&msg, const T err_ret) {
+        if (!failed) err = std::move(msg);
+
+        failed = true;
+        return err_ret;
+    }
+
+    /* consume_whitespace()
+     *
+     * Advance until the current character is non-whitespace.
+     */
+    void consume_whitespace() {
+        while (str[i] == ' ' || str[i] == '\r' || str[i] == '\n' || str[i] == '\t')
+            i++;
+    }
+
+    /* consume_comment()
+     *
+     * Advance comments (c-style inline and multiline).
+     */
+    bool consume_comment() {
+        bool comment_found = false;
+
+        if (str[i] == '/') {
+            i++;
+
+            if (i == str.size()) return fail("unexpected end of input after start of comment", false);
+
+            if (str[i] == '/') { // inline comment
+                i++;
+
+                // advance until next line, or end of input
+                while (i < str.size() && str[i] != '\n')
+                    i++;
+                comment_found = true;
+            } else if (str[i] == '*') { // multiline comment
+                i++;
+
+                if (i > str.size() - 2) return fail("unexpected end of input inside multi-line comment", false);
+
+                // advance until closing tokens
+                while (!(str[i] == '*' && str[i + 1] == '/')) {
+                    i++;
+
+                    if (i > str.size() - 2) return fail(
+                            "unexpected end of input inside multi-line comment", false);
+                }
+                i += 2;
+                comment_found = true;
+            } else return fail("malformed comment", false);
+        }
+
+        return comment_found;
+    }
+
+    /* consume_garbage()
+     *
+     * Advance until the current character is non-whitespace and non-comment.
+     */
+    void consume_garbage() {
+        consume_whitespace();
+
+        if (strategy == JsonParse::COMMENTS) {
+            bool comment_found = false;
+            do {
+                comment_found = consume_comment();
+
+                if (failed) return;
+
+                consume_whitespace();
+            } while (comment_found);
+        }
+    }
+
+    /* get_next_token()
+     *
+     * Return the next non-whitespace character. If the end of the input is reached,
+     * flag an error and return 0.
+     */
+    char get_next_token() {
+        consume_garbage();
+
+        if (failed) return (char)0;
+
+        if (i == str.size()) return fail("unexpected end of input", (char)0);
+
+        return str[i++];
+    }
+
+    /* encode_utf8(pt, out)
+     *
+     * Encode pt as UTF-8 and add it to out.
+     */
+    void encode_utf8(long pt, string & out) {
+        if (pt < 0) return;
+
+        if (pt < 0x80) {
+            out += static_cast<char>(pt);
+        } else if (pt < 0x800) {
+            out += static_cast<char>((pt >> 6) | 0xC0);
+            out += static_cast<char>((pt & 0x3F) | 0x80);
+        } else if (pt < 0x10000) {
+            out += static_cast<char>((pt >> 12) | 0xE0);
+            out += static_cast<char>(((pt >> 6) & 0x3F) | 0x80);
+            out += static_cast<char>((pt & 0x3F) | 0x80);
+        } else {
+            out += static_cast<char>((pt >> 18) | 0xF0);
+            out += static_cast<char>(((pt >> 12) & 0x3F) | 0x80);
+            out += static_cast<char>(((pt >> 6) & 0x3F) | 0x80);
+            out += static_cast<char>((pt & 0x3F) | 0x80);
+        }
+    }
+
+    /* parse_string()
+     *
+     * Parse a string, starting at the current position.
+     */
+    string parse_string() {
+        string out;
+        long last_escaped_codepoint = -1;
+
+        while (true) {
+            if (i == str.size()) return fail("unexpected end of input in string", "");
+
+            char ch = str[i++];
+
+            if (ch == '"') {
+                encode_utf8(last_escaped_codepoint, out);
+                return out;
+            }
+
+            if (in_range(ch, 0, 0x1f)) return fail("unescaped " + esc(ch) + " in string", "");
+
+            // The usual case: non-escaped characters
+            if (ch != '\\') {
+                encode_utf8(last_escaped_codepoint, out);
+                last_escaped_codepoint = -1;
+                out += ch;
+                continue;
+            }
+
+            // Handle escapes
+            if (i == str.size()) return fail("unexpected end of input in string", "");
+
+            ch = str[i++];
+
+            if (ch == 'u') {
+                // Extract 4-byte escape sequence
+                string esc = str.substr(i, 4);
+
+                // Explicitly check length of the substring. The following loop
+                // relies on std::string returning the terminating NUL when
+                // accessing str[length]. Checking here reduces brittleness.
+                if (esc.length() < 4) {
+                    return fail("bad \\u escape: " + esc, "");
+                }
+
+                for (size_t j = 0; j < 4; j++) {
+                    if (!in_range(esc[j], 'a', 'f') && !in_range(esc[j], 'A', 'F')
+                        && !in_range(esc[j], '0', '9')) return fail("bad \\u escape: " + esc, "");
+                }
+
+                long codepoint = strtol(esc.data(), nullptr, 16);
+
+                // JSON specifies that characters outside the BMP shall be encoded as a pair
+                // of 4-hex-digit \u escapes encoding their surrogate pair components. Check
+                // whether we're in the middle of such a beast: the previous codepoint was an
+                // escaped lead (high) surrogate, and this is a trail (low) surrogate.
+                if (in_range(last_escaped_codepoint, 0xD800, 0xDBFF)
+                    && in_range(codepoint, 0xDC00, 0xDFFF)) {
+                    // Reassemble the two surrogate pairs into one astral-plane character, per
+                    // the UTF-16 algorithm.
+                    encode_utf8((((last_escaped_codepoint - 0xD800) << 10)
+                                 | (codepoint - 0xDC00)) + 0x10000, out);
+                    last_escaped_codepoint = -1;
+                } else {
+                    encode_utf8(last_escaped_codepoint, out);
+                    last_escaped_codepoint = codepoint;
+                }
+
+                i += 4;
+                continue;
+            }
+
+            encode_utf8(last_escaped_codepoint, out);
+            last_escaped_codepoint = -1;
+
+            if (ch == 'b') {
+                out += '\b';
+            } else if (ch == 'f') {
+                out += '\f';
+            } else if (ch == 'n') {
+                out += '\n';
+            } else if (ch == 'r') {
+                out += '\r';
+            } else if (ch == 't') {
+                out += '\t';
+            } else if (ch == '"' || ch == '\\' || ch == '/') {
+                out += ch;
+            } else {
+                return fail("invalid escape character " + esc(ch), "");
+            }
+        }
+    }
+
+    /* parse_number()
+     *
+     * Parse a double.
+     */
+    Json parse_number() {
+        size_t start_pos = i;
+
+        if (str[i] == '-') i++;
+
+        // Integer part
+        if (str[i] == '0') {
+            i++;
+
+            if (in_range(str[i], '0', '9')) return fail("leading 0s not permitted in numbers");
+        } else if (in_range(str[i], '1', '9')) {
+            i++;
+
+            while (in_range(str[i], '0', '9'))
+                i++;
+        } else {
+            return fail("invalid " + esc(str[i]) + " in number");
+        }
+
+        if (str[i] != '.' && str[i] != 'e' && str[i] != 'E'
+            && (i - start_pos) <= static_cast<size_t>(std::numeric_limits<int>::digits10)) {
+            return std::atoi(str.c_str() + start_pos);
+        }
+
+        // Decimal part
+        if (str[i] == '.') {
+            i++;
+
+            if (!in_range(str[i], '0', '9')) return fail("at least one digit required in fractional part");
+
+            while (in_range(str[i], '0', '9'))
+                i++;
+        }
+
+        // Exponent part
+        if (str[i] == 'e' || str[i] == 'E') {
+            i++;
+
+            if (str[i] == '+' || str[i] == '-') i++;
+
+            if (!in_range(str[i], '0', '9')) return fail("at least one digit required in exponent");
+
+            while (in_range(str[i], '0', '9'))
+                i++;
+        }
+
+        return std::strtod(str.c_str() + start_pos, nullptr);
+    }
+
+    /* expect(str, res)
+     *
+     * Expect that 'str' starts at the character that was just read. If it does, advance
+     * the input and return res. If not, flag an error.
+     */
+    Json expect(const string &expected, Json res) {
+        assert(i != 0);
+        i--;
+
+        if (str.compare(i, expected.length(), expected) == 0) {
+            i += expected.length();
+            return res;
+        } else {
+            return fail("parse error: expected " + expected + ", got " + str.substr(i, expected.length()));
+        }
+    }
+
+    /* parse_json()
+     *
+     * Parse a JSON object.
+     */
+    Json parse_json(int depth) {
+        if (depth > max_depth) {
+            return fail("exceeded maximum nesting depth");
+        }
+
+        char ch = get_next_token();
+
+        if (failed) return Json();
+
+        if (ch == '-' || (ch >= '0' && ch <= '9')) {
+            i--;
+            return parse_number();
+        }
+
+        if (ch == 't') return expect("true", true);
+
+        if (ch == 'f') return expect("false", false);
+
+        if (ch == 'n') return expect("null", Json());
+
+        if (ch == '"') return parse_string();
+
+        if (ch == '{') {
+            map<string, Json> data;
+            ch = get_next_token();
+
+            if (ch == '}') return data;
+
+            while (1) {
+                if (ch != '"') return fail("expected '\"' in object, got " + esc(ch));
+
+                string key = parse_string();
+
+                if (failed) return Json();
+
+                ch = get_next_token();
+
+                if (ch != ':') return fail("expected ':' in object, got " + esc(ch));
+
+                data[std::move(key)] = parse_json(depth + 1);
+
+                if (failed) return Json();
+
+                ch = get_next_token();
+
+                if (ch == '}') break;
+
+                if (ch != ',') return fail("expected ',' in object, got " + esc(ch));
+
+                ch = get_next_token();
+            }
+            return data;
+        }
+
+        if (ch == '[') {
+            vector<Json> data;
+            ch = get_next_token();
+
+            if (ch == ']') return data;
+
+            while (1) {
+                i--;
+                data.push_back(parse_json(depth + 1));
+
+                if (failed) return Json();
+
+                ch = get_next_token();
+
+                if (ch == ']') break;
+
+                if (ch != ',') return fail("expected ',' in list, got " + esc(ch));
+
+                ch = get_next_token();
+                (void)ch;
+            }
+            return data;
+        }
+
+        return fail("expected value, got " + esc(ch));
+    }
+};
+}//namespace {
+
+Json Json::parse(const string &in, string &err, JsonParse strategy) {
+    JsonParser parser { in, 0, err, false, strategy };
+    Json result = parser.parse_json(0);
+
+    // Check for any trailing garbage
+    parser.consume_garbage();
+
+    if (parser.failed) return Json();
+
+    if (parser.i != in.size()) return parser.fail("unexpected trailing " + esc(in[parser.i]));
+
+    return result;
+}
+
+// Documented in json11.hpp
+vector<Json> Json::parse_multi(const string &          in,
+                               std::string::size_type &parser_stop_pos,
+                               string &                err,
+                               JsonParse               strategy) {
+    JsonParser parser { in, 0, err, false, strategy };
+
+    parser_stop_pos = 0;
+    vector<Json> json_vec;
+
+    while (parser.i != in.size() && !parser.failed) {
+        json_vec.push_back(parser.parse_json(0));
+
+        if (parser.failed) break;
+
+        // Check for another object
+        parser.consume_garbage();
+
+        if (parser.failed) break;
+
+        parser_stop_pos = parser.i;
+    }
+    return json_vec;
+}
+
+/* * * * * * * * * * * * * * * * * * * *
+ * Shape-checking
+ */
+
+bool Json::has_shape(const shape & types, string & err) const {
+    if (!is_object()) {
+        err = "expected JSON object, got " + dump();
+        return false;
+    }
+
+    for (auto & item : types) {
+        if ((*this)[item.first].type() != item.second) {
+            err = "bad type for " + item.first + " in " + dump();
+            return false;
+        }
+    }
+
+    return true;
+}
+} // namespace json11

json11.hpp

@@ -0,0 +1,263 @@
+/* json11
+ *
+ * json11 is a tiny JSON library for C++11, providing JSON parsing and serialization.
+ *
+ * The core object provided by the library is json11::Json. A Json object represents any JSON
+ * value: null, bool, number (int or double), string (std::string), array (std::vector), or
+ * object (std::map).
+ *
+ * Json objects act like values: they can be assigned, copied, moved, compared for equality or
+ * order, etc. There are also helper methods Json::dump, to serialize a Json to a string, and
+ * Json::parse (static) to parse a std::string as a Json object.
+ *
+ * Internally, the various types of Json object are represented by the JsonValue class
+ * hierarchy.
+ *
+ * A note on numbers - JSON specifies the syntax of number formatting but not its semantics,
+ * so some JSON implementations distinguish between integers and floating-point numbers, while
+ * some don't. In json11, we choose the latter. Because some JSON implementations (namely
+ * Javascript itself) treat all numbers as the same type, distinguishing the two leads
+ * to JSON that will be *silently* changed by a round-trip through those implementations.
+ * Dangerous! To avoid that risk, json11 stores all numbers as double internally, but also
+ * provides integer helpers.
+ *
+ * Fortunately, double-precision IEEE754 ('double') can precisely store any integer in the
+ * range +/-2^53, which includes every 'int' on most systems. (Timestamps often use int64
+ * or long long to avoid the Y2038K problem; a double storing microseconds since some epoch
+ * will be exact for +/- 275 years.)
+ */
+
+/* Copyright (c) 2013 Dropbox, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#pragma once
+
+#include <string>
+#include <vector>
+#include <map>
+#include <memory>
+#include <initializer_list>
+
+#ifdef _MSC_VER
+    #if _MSC_VER <= 1800 // VS 2013
+        #ifndef noexcept
+            #define noexcept throw()
+        #endif
+
+        #ifndef snprintf
+            #define snprintf _snprintf_s
+        #endif
+    #endif
+#endif
+
+namespace json11 {
+enum JsonParse {
+    STANDARD, COMMENTS
+};
+
+class JsonValue;
+
+class Json final {
+public:
+// Types
+enum Type {
+    NUL, NUMBER, BOOL, STRING, ARRAY, OBJECT
+};
+
+// Array and object typedefs
+typedef std::vector<Json>             array;
+typedef std::map<std::string, Json>   object;
+
+// Constructors for the various types of JSON value.
+Json() noexcept;                    // NUL
+Json(std::nullptr_t) noexcept;      // NUL
+Json(double value);                 // NUMBER
+Json(int value);                    // NUMBER
+Json(bool value);                   // BOOL
+Json(const std::string &value);     // STRING
+Json(std::string &&value);          // STRING
+Json(const char *value);            // STRING
+Json(const array &values);          // ARRAY
+Json(array &&values);               // ARRAY
+Json(const object &values);         // OBJECT
+Json(object &&values);              // OBJECT
+
+// Implicit constructor: anything with a to_json() function.
+template <class T, class = decltype(&T::to_json)>
+Json(const T & t) : Json(t.to_json()) {
+}
+
+// Implicit constructor: map-like objects (std::map, std::unordered_map, etc)
+template <class M, typename std::enable_if<
+              std::is_constructible<std::string, decltype(std::declval<M>().begin()->first)>::value
+              && std::is_constructible<Json, decltype(std::declval<M>().begin()->second)>::value,
+              int>::type = 0>
+Json(const M & m) : Json(object(m.begin(), m.end())) {
+}
+
+// Implicit constructor: vector-like objects (std::list, std::vector, std::set, etc)
+template <class V, typename std::enable_if<
+              std::is_constructible<Json, decltype(*std::declval<V>().begin())>::value,
+              int>::type = 0>
+Json(const V & v) : Json(array(v.begin(), v.end())) {
+}
+
+// This prevents Json(some_pointer) from accidentally producing a bool. Use
+// Json(bool(some_pointer)) if that behavior is desired.
+Json(void *) = delete;
+
+// Accessors
+Type type() const;
+
+bool is_null()   const {
+    return type() == NUL;
+}
+
+bool is_number() const {
+    return type() == NUMBER;
+}
+
+bool is_bool()   const {
+    return type() == BOOL;
+}
+
+bool is_string() const {
+    return type() == STRING;
+}
+
+bool is_array()  const {
+    return type() == ARRAY;
+}
+
+bool is_object() const {
+    return type() == OBJECT;
+}
+
+// Return the enclosed value if this is a number, 0 otherwise. Note that json11 does not
+// distinguish between integer and non-integer numbers - number_value() and int_value()
+// can both be applied to a NUMBER-typed object.
+double number_value() const;
+int int_value() const;
+
+// Return the enclosed value if this is a boolean, false otherwise.
+bool bool_value() const;
+// Return the enclosed string if this is a string, "" otherwise.
+const std::string &string_value() const;
+// Return the enclosed std::vector if this is an array, or an empty vector otherwise.
+const array &array_items() const;
+// Return the enclosed std::map if this is an object, or an empty map otherwise.
+const object &object_items() const;
+
+// Return a reference to arr[i] if this is an array, Json() otherwise.
+const Json & operator[](size_t i) const;
+// Return a reference to obj[key] if this is an object, Json() otherwise.
+const Json & operator[](const std::string &key) const;
+
+// Serialize.
+void dump(std::string &out) const;
+std::string dump() const {
+    std::string out;
+    dump(out);
+    return out;
+}
+
+// Parse. If parse fails, return Json() and assign an error message to err.
+static Json parse(const std::string & in,
+                  std::string &       err,
+                  JsonParse           strategy = JsonParse::STANDARD);
+static Json parse(const char    *in,
+                  std::string & err,
+                  JsonParse     strategy = JsonParse::STANDARD) {
+    if (in) {
+        return parse(std::string(in), err, strategy);
+    } else {
+        err = "null input";
+        return nullptr;
+    }
+}
+
+// Parse multiple objects, concatenated or separated by whitespace
+static std::vector<Json> parse_multi(
+    const std::string &      in,
+    std::string::size_type & parser_stop_pos,
+    std::string &            err,
+    JsonParse                strategy = JsonParse::STANDARD);
+
+static inline std::vector<Json> parse_multi(
+    const std::string & in,
+    std::string &       err,
+    JsonParse           strategy = JsonParse::STANDARD) {
+    std::string::size_type parser_stop_pos;
+    return parse_multi(in, parser_stop_pos, err, strategy);
+}
+
+bool operator==(const Json &rhs) const;
+bool operator<(const Json &rhs) const;
+bool operator!=(const Json &rhs) const {
+    return !(*this == rhs);
+}
+
+bool operator<=(const Json &rhs) const {
+    return !(rhs < *this);
+}
+
+bool operator>(const Json &rhs) const {
+    return  (rhs < *this);
+}
+
+bool operator>=(const Json &rhs) const {
+    return !(*this < rhs);
+}
+
+/* has_shape(types, err)
+ *
+ * Return true if this is a JSON object and, for each item in types, has a field of
+ * the given type. If not, return false and set err to a descriptive message.
+ */
+typedef std::initializer_list<std::pair<std::string, Type> > shape;
+bool has_shape(const shape & types, std::string & err) const;
+
+private:
+std::shared_ptr<JsonValue> m_ptr;
+};
+
+// Internal class hierarchy - JsonValue objects are not exposed to users of this API.
+class JsonValue {
+protected:
+friend class Json;
+friend class JsonInt;
+friend class JsonDouble;
+virtual Json::Type type() const = 0;
+virtual bool equals(const JsonValue *other) const = 0;
+virtual bool less(const JsonValue *other) const = 0;
+virtual void dump(std::string &out) const = 0;
+virtual double number_value() const;
+virtual int int_value() const;
+virtual bool bool_value() const;
+virtual const std::string &string_value() const;
+virtual const Json::array &array_items() const;
+virtual const Json &operator[](size_t i) const;
+virtual const Json::object &object_items() const;
+virtual const Json &operator[](const std::string &key) const;
+virtual ~JsonValue() {
+}
+};
+} // namespace json11

udpserver.cpp

@@ -0,0 +1,153 @@
+/* g++ -o udpserver udpserver.cpp -std=c++11 json11.cpp -pthread -s -O2 */
+/* udpserver 127.0.0.1 10003 */
+
+#include <iostream>
+#include <sstream>
+#include <arpa/inet.h>
+#include <unistd.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <time.h>
+#include <iterator>
+#include <unistd.h>
+#include <stack>
+#include <vector>
+#include <signal.h>
+
+#include <thread>
+
+#include "json11.hpp"
+
+using namespace std;
+using namespace json11;
+
+int sockfd;
+
+int StopFlag = 1;
+
+void error(char *msg) {
+    perror(msg);
+    exit(EXIT_FAILURE);
+}
+
+void termHandler(int i);
+void threadProc(int tnum);
+
+void printLog(string severity, string msg) {
+    char buff[20];
+    struct tm *sTm;
+
+    time_t now = time(0);
+
+    sTm = gmtime(&now);
+
+    strftime(buff, sizeof(buff), "%Y-%m-%dT%H:%M:%S", sTm);
+
+    Json my_json = Json::object {
+        { "msg", msg },
+        { "severity", severity },
+        { "time", buff }
+    };
+    string json_obj_str = my_json.dump();
+    cout << json_obj_str << "\n";
+}
+
+int main(int argc, char **argv) {
+    struct sigaction sa;
+    sigset_t newset;
+
+    sigemptyset(&newset);
+    sigaddset(&newset, SIGHUP);
+    sigprocmask(SIG_BLOCK, &newset, 0);
+    sa.sa_handler = termHandler;
+    sigaction(SIGTERM, &sa, 0);
+
+    unsigned int nthreads = thread::hardware_concurrency();
+    stringstream ss;
+    ss << nthreads;
+    printLog("INFO", "Hardware concurrency (CPU)... " + ss.str());
+
+    sockfd = socket(AF_INET, SOCK_DGRAM, 0);
+    struct sockaddr_in server;
+
+    if (argc >= 3) {
+        char *host = argv[1];
+        int port = atoi(argv[2]);
+
+        // UDP Server
+        server.sin_family = AF_INET;
+        server.sin_port = htons(port);
+        server.sin_addr.s_addr = inet_addr(host);
+
+        printLog("INFO", "Binding server to socket... OK");
+
+        if (bind(sockfd, (struct sockaddr *)&server, sizeof(server)) < 0) {
+            perror(NULL);
+            close(sockfd);
+            exit(0);
+        }
+
+        vector<thread> threads(nthreads);
+
+        for (int i = 0; i < nthreads; i++) {
+            stringstream ss;
+            ss << i;
+            printLog("INFO", "Start thread...  " + ss.str());
+            thread thr(threadProc, i);
+            threads[i] = move(thr);
+        }
+
+        while (StopFlag) {
+            sleep(1);
+        }
+
+        for (auto& thr : threads) {
+            thr.join();
+        }
+
+        exit(EXIT_SUCCESS);
+    } else {
+        cout << "udpserver <host> <port>" << endl;
+    }
+}
+
+void threadProc(int tnum) {
+    struct sockaddr_in client;
+
+    stringstream ss;
+
+    ss << tnum;
+    string tnumStr = ss.str();
+    printLog("INFO", "Server thread " + tnumStr + " started... OK");
+
+    while (StopFlag) {
+        char buffer[1024] = {};
+        socklen_t cs = sizeof(client);
+        printLog("INFO", "Waiting for a UDP datagram (" + tnumStr + ")...");
+        int rc = recvfrom(sockfd, buffer, sizeof(buffer), 0, (struct sockaddr *)&client, &cs);
+        printLog("INFO", "Received (" + tnumStr + ")");
+
+        if (rc < 0) {
+            printLog("ERROR", "ERROR READING FROM SOCKET (" + tnumStr + ")!");
+        } else {
+            for (int i = 0; i < rc; i++) {
+                printf("0x%x;", buffer[i]);
+            }
+
+            cout << endl;
+            unsigned char *conbuf = (unsigned char *)buffer;
+        }
+    }
+}
+
+void termHandler(int i) {
+    printLog("INFO", "Server shutdown...");
+    StopFlag = 0;
+    sleep(10);
+    printLog("INFO", "Server stopped... OK");
+
+    exit(EXIT_SUCCESS);
+}