Ed Tanous | af4edf6 | 2020-07-21 08:46:25 -0700 | [diff] [blame] | 1 | #pragma once |
| 2 | |
| 3 | #include <boost/algorithm/string/predicate.hpp> |
| 4 | #include <boost/beast/http/fields.hpp> |
| 5 | #include <http_request.hpp> |
| 6 | |
| 7 | #include <string> |
| 8 | #include <string_view> |
| 9 | |
| 10 | enum class ParserError |
| 11 | { |
| 12 | PARSER_SUCCESS, |
| 13 | ERROR_BOUNDARY_FORMAT, |
| 14 | ERROR_BOUNDARY_CR, |
| 15 | ERROR_BOUNDARY_LF, |
| 16 | ERROR_BOUNDARY_DATA, |
| 17 | ERROR_EMPTY_HEADER, |
| 18 | ERROR_HEADER_NAME, |
| 19 | ERROR_HEADER_VALUE, |
| 20 | ERROR_HEADER_ENDING |
| 21 | }; |
| 22 | |
| 23 | enum class State |
| 24 | { |
| 25 | START, |
| 26 | START_BOUNDARY, |
| 27 | HEADER_FIELD_START, |
| 28 | HEADER_FIELD, |
| 29 | HEADER_VALUE_START, |
| 30 | HEADER_VALUE, |
| 31 | HEADER_VALUE_ALMOST_DONE, |
| 32 | HEADERS_ALMOST_DONE, |
| 33 | PART_DATA_START, |
| 34 | PART_DATA, |
| 35 | END |
| 36 | }; |
| 37 | |
| 38 | enum class Boundary |
| 39 | { |
| 40 | NON_BOUNDARY, |
| 41 | PART_BOUNDARY, |
| 42 | END_BOUNDARY, |
| 43 | }; |
| 44 | |
| 45 | struct FormPart |
| 46 | { |
| 47 | boost::beast::http::fields fields; |
| 48 | std::string content; |
| 49 | }; |
| 50 | |
| 51 | class MultipartParser |
| 52 | { |
| 53 | public: |
| 54 | MultipartParser() = default; |
| 55 | |
| 56 | [[nodiscard]] ParserError parse(const crow::Request& req) |
| 57 | { |
| 58 | std::string_view contentType = req.getHeaderValue("content-type"); |
| 59 | |
| 60 | const std::string boundaryFormat = "multipart/form-data; boundary="; |
| 61 | if (!boost::starts_with(req.getHeaderValue("content-type"), |
| 62 | boundaryFormat)) |
| 63 | { |
| 64 | return ParserError::ERROR_BOUNDARY_FORMAT; |
| 65 | } |
| 66 | |
| 67 | std::string_view ctBoundary = contentType.substr(boundaryFormat.size()); |
| 68 | |
| 69 | boundary = "\r\n--"; |
| 70 | boundary += ctBoundary; |
| 71 | indexBoundary(); |
| 72 | lookbehind.resize(boundary.size() + 8); |
| 73 | state = State::START; |
| 74 | |
| 75 | const char* buffer = req.body.data(); |
| 76 | size_t len = req.body.size(); |
| 77 | size_t prevIndex = index; |
| 78 | char cl = 0; |
| 79 | |
| 80 | for (size_t i = 0; i < len; i++) |
| 81 | { |
Ed Tanous | ca45aa3 | 2022-01-07 09:28:45 -0800 | [diff] [blame^] | 82 | // NOLINTNEXTLINE(cppcoreguidelines-pro-bounds-pointer-arithmetic) |
Ed Tanous | af4edf6 | 2020-07-21 08:46:25 -0700 | [diff] [blame] | 83 | char c = buffer[i]; |
| 84 | switch (state) |
| 85 | { |
| 86 | case State::START: |
| 87 | index = 0; |
| 88 | state = State::START_BOUNDARY; |
| 89 | [[fallthrough]]; |
| 90 | case State::START_BOUNDARY: |
| 91 | if (index == boundary.size() - 2) |
| 92 | { |
| 93 | if (c != cr) |
| 94 | { |
| 95 | return ParserError::ERROR_BOUNDARY_CR; |
| 96 | } |
| 97 | index++; |
| 98 | break; |
| 99 | } |
| 100 | else if (index - 1 == boundary.size() - 2) |
| 101 | { |
| 102 | if (c != lf) |
| 103 | { |
| 104 | return ParserError::ERROR_BOUNDARY_LF; |
| 105 | } |
| 106 | index = 0; |
| 107 | mime_fields.push_back({}); |
| 108 | state = State::HEADER_FIELD_START; |
| 109 | break; |
| 110 | } |
| 111 | if (c != boundary[index + 2]) |
| 112 | { |
| 113 | return ParserError::ERROR_BOUNDARY_DATA; |
| 114 | } |
| 115 | index++; |
| 116 | break; |
| 117 | case State::HEADER_FIELD_START: |
| 118 | currentHeaderName.resize(0); |
| 119 | state = State::HEADER_FIELD; |
| 120 | headerFieldMark = i; |
| 121 | index = 0; |
| 122 | [[fallthrough]]; |
| 123 | case State::HEADER_FIELD: |
| 124 | if (c == cr) |
| 125 | { |
| 126 | headerFieldMark = 0; |
| 127 | state = State::HEADERS_ALMOST_DONE; |
| 128 | break; |
| 129 | } |
| 130 | |
| 131 | index++; |
| 132 | if (c == hyphen) |
| 133 | { |
| 134 | break; |
| 135 | } |
| 136 | |
| 137 | if (c == colon) |
| 138 | { |
| 139 | if (index == 1) |
| 140 | { |
| 141 | return ParserError::ERROR_EMPTY_HEADER; |
| 142 | } |
Ed Tanous | ca45aa3 | 2022-01-07 09:28:45 -0800 | [diff] [blame^] | 143 | |
| 144 | // NOLINTNEXTLINE(cppcoreguidelines-pro-bounds-pointer-arithmetic) |
Ed Tanous | af4edf6 | 2020-07-21 08:46:25 -0700 | [diff] [blame] | 145 | currentHeaderName.append(buffer + headerFieldMark, |
| 146 | i - headerFieldMark); |
| 147 | state = State::HEADER_VALUE_START; |
| 148 | break; |
| 149 | } |
| 150 | cl = lower(c); |
| 151 | if (cl < 'a' || cl > 'z') |
| 152 | { |
| 153 | return ParserError::ERROR_HEADER_NAME; |
| 154 | } |
| 155 | break; |
| 156 | case State::HEADER_VALUE_START: |
| 157 | if (c == space) |
| 158 | { |
| 159 | break; |
| 160 | } |
| 161 | headerValueMark = i; |
| 162 | state = State::HEADER_VALUE; |
| 163 | [[fallthrough]]; |
| 164 | case State::HEADER_VALUE: |
| 165 | if (c == cr) |
| 166 | { |
Ed Tanous | ca45aa3 | 2022-01-07 09:28:45 -0800 | [diff] [blame^] | 167 | // NOLINTNEXTLINE(cppcoreguidelines-pro-bounds-pointer-arithmetic) |
Ed Tanous | af4edf6 | 2020-07-21 08:46:25 -0700 | [diff] [blame] | 168 | std::string_view value(buffer + headerValueMark, |
| 169 | i - headerValueMark); |
| 170 | mime_fields.rbegin()->fields.set(currentHeaderName, |
| 171 | value); |
| 172 | state = State::HEADER_VALUE_ALMOST_DONE; |
| 173 | } |
| 174 | break; |
| 175 | case State::HEADER_VALUE_ALMOST_DONE: |
| 176 | if (c != lf) |
| 177 | { |
| 178 | return ParserError::ERROR_HEADER_VALUE; |
| 179 | } |
| 180 | state = State::HEADER_FIELD_START; |
| 181 | break; |
| 182 | case State::HEADERS_ALMOST_DONE: |
| 183 | if (c != lf) |
| 184 | { |
| 185 | return ParserError::ERROR_HEADER_ENDING; |
| 186 | } |
| 187 | state = State::PART_DATA_START; |
| 188 | break; |
| 189 | case State::PART_DATA_START: |
| 190 | state = State::PART_DATA; |
| 191 | partDataMark = i; |
| 192 | [[fallthrough]]; |
| 193 | case State::PART_DATA: |
| 194 | if (index == 0) |
| 195 | { |
| 196 | skipNonBoundary(buffer, len, boundary.size() - 1, i); |
Ed Tanous | ca45aa3 | 2022-01-07 09:28:45 -0800 | [diff] [blame^] | 197 | |
| 198 | // NOLINTNEXTLINE(cppcoreguidelines-pro-bounds-pointer-arithmetic) |
Ed Tanous | af4edf6 | 2020-07-21 08:46:25 -0700 | [diff] [blame] | 199 | c = buffer[i]; |
| 200 | } |
| 201 | processPartData(prevIndex, index, buffer, i, c, state); |
| 202 | break; |
| 203 | case State::END: |
| 204 | break; |
| 205 | } |
| 206 | } |
| 207 | return ParserError::PARSER_SUCCESS; |
| 208 | } |
| 209 | std::vector<FormPart> mime_fields; |
| 210 | std::string boundary; |
| 211 | |
| 212 | private: |
| 213 | void indexBoundary() |
| 214 | { |
| 215 | std::fill(boundaryIndex.begin(), boundaryIndex.end(), 0); |
| 216 | for (const char current : boundary) |
| 217 | { |
| 218 | boundaryIndex[static_cast<unsigned char>(current)] = true; |
| 219 | } |
| 220 | } |
| 221 | |
| 222 | char lower(char c) const |
| 223 | { |
| 224 | return static_cast<char>(c | 0x20); |
| 225 | } |
| 226 | |
| 227 | inline bool isBoundaryChar(char c) const |
| 228 | { |
| 229 | return boundaryIndex[static_cast<unsigned char>(c)]; |
| 230 | } |
| 231 | |
| 232 | void skipNonBoundary(const char* buffer, size_t len, size_t boundaryEnd, |
| 233 | size_t& i) |
| 234 | { |
| 235 | // boyer-moore derived algorithm to safely skip non-boundary data |
| 236 | while (i + boundary.size() <= len) |
| 237 | { |
Ed Tanous | ca45aa3 | 2022-01-07 09:28:45 -0800 | [diff] [blame^] | 238 | // NOLINTNEXTLINE(cppcoreguidelines-pro-bounds-pointer-arithmetic) |
Ed Tanous | af4edf6 | 2020-07-21 08:46:25 -0700 | [diff] [blame] | 239 | if (isBoundaryChar(buffer[i + boundaryEnd])) |
| 240 | { |
| 241 | break; |
| 242 | } |
| 243 | i += boundary.size(); |
| 244 | } |
| 245 | } |
| 246 | |
| 247 | void processPartData(size_t& prevIndex, size_t& index, const char* buffer, |
| 248 | size_t& i, char c, State& state) |
| 249 | { |
| 250 | prevIndex = index; |
| 251 | |
| 252 | if (index < boundary.size()) |
| 253 | { |
| 254 | if (boundary[index] == c) |
| 255 | { |
| 256 | if (index == 0) |
| 257 | { |
Ed Tanous | ca45aa3 | 2022-01-07 09:28:45 -0800 | [diff] [blame^] | 258 | // NOLINTNEXTLINE(cppcoreguidelines-pro-bounds-pointer-arithmetic) |
| 259 | const char* start = buffer + partDataMark; |
| 260 | size_t size = i - partDataMark; |
| 261 | mime_fields.rbegin()->content += |
| 262 | std::string_view(start, size); |
Ed Tanous | af4edf6 | 2020-07-21 08:46:25 -0700 | [diff] [blame] | 263 | } |
| 264 | index++; |
| 265 | } |
| 266 | else |
| 267 | { |
| 268 | index = 0; |
| 269 | } |
| 270 | } |
| 271 | else if (index == boundary.size()) |
| 272 | { |
| 273 | index++; |
| 274 | if (c == cr) |
| 275 | { |
| 276 | // cr = part boundary |
| 277 | flags = Boundary::PART_BOUNDARY; |
| 278 | } |
| 279 | else if (c == hyphen) |
| 280 | { |
| 281 | // hyphen = end boundary |
| 282 | flags = Boundary::END_BOUNDARY; |
| 283 | } |
| 284 | else |
| 285 | { |
| 286 | index = 0; |
| 287 | } |
| 288 | } |
| 289 | else |
| 290 | { |
| 291 | if (flags == Boundary::PART_BOUNDARY) |
| 292 | { |
| 293 | index = 0; |
| 294 | if (c == lf) |
| 295 | { |
| 296 | // unset the PART_BOUNDARY flag |
| 297 | flags = Boundary::NON_BOUNDARY; |
| 298 | mime_fields.push_back({}); |
| 299 | state = State::HEADER_FIELD_START; |
| 300 | return; |
| 301 | } |
| 302 | } |
| 303 | if (flags == Boundary::END_BOUNDARY) |
| 304 | { |
| 305 | if (c == hyphen) |
| 306 | { |
| 307 | state = State::END; |
| 308 | } |
| 309 | } |
| 310 | } |
| 311 | |
| 312 | if (index > 0) |
| 313 | { |
| 314 | lookbehind[index - 1] = c; |
| 315 | } |
| 316 | else if (prevIndex > 0) |
| 317 | { |
| 318 | // if our boundary turned out to be rubbish, the captured |
| 319 | // lookbehind belongs to partData |
| 320 | |
| 321 | mime_fields.rbegin()->content += lookbehind.substr(0, prevIndex); |
| 322 | prevIndex = 0; |
| 323 | partDataMark = i; |
| 324 | |
| 325 | // reconsider the current character even so it interrupted |
| 326 | // the sequence it could be the beginning of a new sequence |
| 327 | i--; |
| 328 | } |
| 329 | } |
| 330 | |
| 331 | std::string currentHeaderName; |
| 332 | std::string currentHeaderValue; |
| 333 | |
| 334 | static constexpr char cr = '\r'; |
| 335 | static constexpr char lf = '\n'; |
| 336 | static constexpr char space = ' '; |
| 337 | static constexpr char hyphen = '-'; |
| 338 | static constexpr char colon = ':'; |
| 339 | |
| 340 | std::array<bool, 256> boundaryIndex; |
| 341 | std::string lookbehind; |
| 342 | State state; |
| 343 | Boundary flags; |
| 344 | size_t index = 0; |
| 345 | size_t partDataMark = 0; |
| 346 | size_t headerFieldMark = 0; |
| 347 | size_t headerValueMark = 0; |
| 348 | }; |