net/ftp/ftp_directory_listing_parser_ls.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "net/ftp/ftp_directory_listing_parser_ls.h"
   6
   7 #include <vector>
   8
   9 #include "base/strings/string_number_conversions.h"
  10 #include "base/strings/string_split.h"
  11 #include "base/strings/string_util.h"
  12 #include "base/strings/utf_string_conversions.h"
  13 #include "base/time/time.h"
  14 #include "net/ftp/ftp_directory_listing_parser.h"
  15 #include "net/ftp/ftp_util.h"
  16
  17 namespace net {
  18
  19 namespace {
  20
  21 bool TwoColumnDateListingToTime(const base::string16& date,
  22                                 const base::string16& time,
  23                                 base::Time* result) {
  24   base::Time::Exploded time_exploded = { 0 };
  25
  26   // Date should be in format YYYY-MM-DD.
  27   std::vector<base::string16> date_parts =
  28       base::SplitString(date, base::ASCIIToUTF16("-"), base::TRIM_WHITESPACE,
  29                         base::SPLIT_WANT_ALL);
  30   if (date_parts.size() != 3)
  31     return false;
  32   if (!base::StringToInt(date_parts[0], &time_exploded.year))
  33     return false;
  34   if (!base::StringToInt(date_parts[1], &time_exploded.month))
  35     return false;
  36   if (!base::StringToInt(date_parts[2], &time_exploded.day_of_month))
  37     return false;
  38
  39   // Time should be in format HH:MM
  40   if (time.length() != 5)
  41     return false;
  42
  43   std::vector<base::string16> time_parts =
  44       base::SplitString(time, base::ASCIIToUTF16(":"), base::TRIM_WHITESPACE,
  45                         base::SPLIT_WANT_ALL);
  46   if (time_parts.size() != 2)
  47     return false;
  48   if (!base::StringToInt(time_parts[0], &time_exploded.hour))
  49     return false;
  50   if (!base::StringToInt(time_parts[1], &time_exploded.minute))
  51     return false;
  52   if (!time_exploded.HasValidValues())
  53     return false;
  54
  55   // We don't know the time zone of the server, so just use local time.
  56   *result = base::Time::FromLocalExploded(time_exploded);
  57   return true;
  58 }
  59
  60 // Returns the column index of the end of the date listing and detected
  61 // last modification time.
  62 bool DetectColumnOffsetSizeAndModificationTime(
  63     const std::vector<base::string16>& columns,
  64     const base::Time& current_time,
  65     size_t* offset,
  66     base::string16* size,
  67     base::Time* modification_time) {
  68   // The column offset can be arbitrarily large if some fields
  69   // like owner or group name contain spaces. Try offsets from left to right
  70   // and use the first one that matches a date listing.
  71   //
  72   // Here is how a listing line should look like. A star ("*") indicates
  73   // a required field:
  74   //
  75   //  * 1. permission listing
  76   //    2. number of links (optional)
  77   //  * 3. owner name (may contain spaces)
  78   //    4. group name (optional, may contain spaces)
  79   //  * 5. size in bytes
  80   //  * 6. month
  81   //  * 7. day of month
  82   //  * 8. year or time <-- column_offset will be the index of this column
  83   //    9. file name (optional, may contain spaces)
  84   for (size_t i = 5U; i < columns.size(); i++) {
  85     if (FtpUtil::LsDateListingToTime(columns[i - 2], columns[i - 1], columns[i],
  86                                      current_time, modification_time)) {
  87       *size = columns[i - 3];
  88       *offset = i;
  89       return true;
  90     }
  91   }
  92
  93   // Some FTP listings have swapped the "month" and "day of month" columns
  94   // (for example Russian listings). We try to recognize them only after making
  95   // sure no column offset works above (this is a more strict way).
  96   for (size_t i = 5U; i < columns.size(); i++) {
  97     if (FtpUtil::LsDateListingToTime(columns[i - 1], columns[i - 2], columns[i],
  98                                      current_time, modification_time)) {
  99       *size = columns[i - 3];
 100       *offset = i;
 101       return true;
 102     }
 103   }
 104
 105   // Some FTP listings use a different date format.
 106   for (size_t i = 5U; i < columns.size(); i++) {
 107     if (TwoColumnDateListingToTime(columns[i - 1],
 108                                    columns[i],
 109                                    modification_time)) {
 110       *size = columns[i - 2];
 111       *offset = i;
 112       return true;
 113     }
 114   }
 115
 116   return false;
 117 }
 118
 119 }  // namespace
 120
 121 bool ParseFtpDirectoryListingLs(
 122     const std::vector<base::string16>& lines,
 123     const base::Time& current_time,
 124     std::vector<FtpDirectoryListingEntry>* entries) {
 125   // True after we have received a "total n" listing header, where n is an
 126   // integer. Only one such header is allowed per listing.
 127   bool received_total_line = false;
 128
 129   for (size_t i = 0; i < lines.size(); i++) {
 130     if (lines[i].empty())
 131       continue;
 132
 133     std::vector<base::string16> columns = base::SplitString(
 134         base::CollapseWhitespace(lines[i], false), base::ASCIIToUTF16(" "),
 135         base::TRIM_WHITESPACE, base::SPLIT_WANT_ALL);
 136
 137     // Some FTP servers put a "total n" line at the beginning of the listing
 138     // (n is an integer). Allow such a line, but only once, and only if it's
 139     // the first non-empty line. Do not match the word exactly, because it may
 140     // be in different languages (at least English and German have been seen
 141     // in the field).
 142     if (columns.size() == 2 && !received_total_line) {
 143       received_total_line = true;
 144
 145       int64 total_number;
 146       if (!base::StringToInt64(columns[1], &total_number))
 147         return false;
 148       if (total_number < 0)
 149         return false;
 150
 151       continue;
 152     }
 153
 154     FtpDirectoryListingEntry entry;
 155
 156     size_t column_offset;
 157     base::string16 size;
 158     if (!DetectColumnOffsetSizeAndModificationTime(columns,
 159                                                    current_time,
 160                                                    &column_offset,
 161                                                    &size,
 162                                                    &entry.last_modified)) {
 163       // Some servers send a message in one of the first few lines.
 164       // All those messages have in common is the string ".:",
 165       // where "." means the current directory, and ":" separates it
 166       // from the rest of the message, which may be empty.
 167       if (lines[i].find(base::ASCIIToUTF16(".:")) != base::string16::npos)
 168         continue;
 169
 170       return false;
 171     }
 172
 173     // Do not check "validity" of the permission listing. It's quirky,
 174     // and some servers send garbage here while other parts of the line are OK.
 175
 176     if (!columns[0].empty() && columns[0][0] == 'l') {
 177       entry.type = FtpDirectoryListingEntry::SYMLINK;
 178     } else if (!columns[0].empty() && columns[0][0] == 'd') {
 179       entry.type = FtpDirectoryListingEntry::DIRECTORY;
 180     } else {
 181       entry.type = FtpDirectoryListingEntry::FILE;
 182     }
 183
 184     if (!base::StringToInt64(size, &entry.size)) {
 185       // Some FTP servers do not separate owning group name from file size,
 186       // like "group1234". We still want to display the file name for that
 187       // entry, but can't really get the size (What if the group is named
 188       // "group1", and the size is in fact 234? We can't distinguish between
 189       // that and "group" with size 1234). Use a dummy value for the size.
 190       entry.size = -1;
 191     }
 192     if (entry.size < 0) {
 193       // Some FTP servers have bugs that cause them to display the file size
 194       // as negative. They're most likely big files like DVD ISO images.
 195       // We still want to display them, so just say the real file size
 196       // is unknown.
 197       entry.size = -1;
 198     }
 199     if (entry.type != FtpDirectoryListingEntry::FILE)
 200       entry.size = -1;
 201
 202     if (column_offset == columns.size() - 1) {
 203       // If the end of the date listing is the last column, there is no file
 204       // name. Some FTP servers send listing entries with empty names.
 205       // It's not obvious how to display such an entry, so we ignore them.
 206       // We don't want to make the parsing fail at this point though.
 207       // Other entries can still be useful.
 208       continue;
 209     }
 210
 211     entry.name = FtpUtil::GetStringPartAfterColumns(lines[i],
 212                                                     column_offset + 1);
 213
 214     if (entry.type == FtpDirectoryListingEntry::SYMLINK) {
 215       base::string16::size_type pos =
 216           entry.name.rfind(base::ASCIIToUTF16(" -> "));
 217
 218       // We don't require the " -> " to be present. Some FTP servers don't send
 219       // the symlink target, possibly for security reasons.
 220       if (pos != base::string16::npos)
 221         entry.name = entry.name.substr(0, pos);
 222     }
 223
 224     entries->push_back(entry);
 225   }
 226
 227   return true;
 228 }
 229
 230 }  // namespace net