Auto merge of #2251 - str4d:2210-tor-quotedstring-escapes, r=nathan-at-least

Handle escapes in Tor QuotedStrings

Also adds a missing copyright header.

Closes #2210.

src/test/torcontrol_tests.cpp

@@ -119,29 +119,60 @@ BOOST_AUTO_TEST_CASE(util_ParseTorReplyMapping)
             {"Foo", "Bar Baz"},
         });
 
-    // Escapes (which are left escaped by the parser)
+    // Escapes
     CheckParseTorReplyMapping(
         "Foo=\"Bar\\ Baz\"", {
-            {"Foo", "Bar\\ Baz"},
+            {"Foo", "Bar Baz"},
         });
     CheckParseTorReplyMapping(
         "Foo=\"Bar\\Baz\"", {
-            {"Foo", "Bar\\Baz"},
+            {"Foo", "BarBaz"},
         });
     CheckParseTorReplyMapping(
         "Foo=\"Bar\\@Baz\"", {
-            {"Foo", "Bar\\@Baz"},
+            {"Foo", "Bar@Baz"},
         });
     CheckParseTorReplyMapping(
         "Foo=\"Bar\\\"Baz\" Spam=\"\\\"Eggs\\\"\"", {
-            {"Foo", "Bar\\\"Baz"},
-            {"Spam", "\\\"Eggs\\\""},
+            {"Foo", "Bar\"Baz"},
+            {"Spam", "\"Eggs\""},
         });
     CheckParseTorReplyMapping(
         "Foo=\"Bar\\\\Baz\"", {
-            {"Foo", "Bar\\\\Baz"},
+            {"Foo", "Bar\\Baz"},
         });
 
+    // C escapes
+    CheckParseTorReplyMapping(
+        "Foo=\"Bar\\nBaz\\t\" Spam=\"\\rEggs\" Octals=\"\\1a\\11\\17\\18\\81\\377\\378\\400\\2222\" Final=Check", {
+            {"Foo", "Bar\nBaz\t"},
+            {"Spam", "\rEggs"},
+            {"Octals", "\1a\11\17\1" "881\377\37" "8\40" "0\222" "2"},
+            {"Final", "Check"},
+        });
+    CheckParseTorReplyMapping(
+        "Valid=Mapping Escaped=\"Escape\\\\\"", {
+            {"Valid", "Mapping"},
+            {"Escaped", "Escape\\"},
+        });
+    CheckParseTorReplyMapping(
+        "Valid=Mapping Bare=\"Escape\\\"", {});
+    CheckParseTorReplyMapping(
+        "OneOctal=\"OneEnd\\1\" TwoOctal=\"TwoEnd\\11\"", {
+            {"OneOctal", "OneEnd\1"},
+            {"TwoOctal", "TwoEnd\11"},
+        });
+
+    // Special handling for null case
+    // (needed because string comparison reads the null as end-of-string)
+    BOOST_TEST_MESSAGE(std::string("CheckParseTorReplyMapping(Null=\"\\0\")"));
+    auto ret = ParseTorReplyMapping("Null=\"\\0\"");
+    BOOST_CHECK_EQUAL(ret.size(), 1);
+    auto r_it = ret.begin();
+    BOOST_CHECK_EQUAL(r_it->first, "Null");
+    BOOST_CHECK_EQUAL(r_it->second.size(), 1);
+    BOOST_CHECK_EQUAL(r_it->second[0], '\0');
+
     // A more complex valid grammar. PROTOCOLINFO accepts a VersionLine that
     // takes a key=value pair followed by an OptArguments, making this valid.
     // Because an OptArguments contains no semantic data, there is no point in

src/torcontrol.cpp

@@ -1,3 +1,8 @@
+// Copyright (c) 2015-2017 The Bitcoin Core developers
+// Copyright (c) 2017 The Zcash developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
 #include "torcontrol.h"
 #include "utilstrencodings.h"
 #include "net.h"
@@ -285,17 +290,61 @@ static std::map<std::string,std::string> ParseTorReplyMapping(const std::string
             ++ptr; // skip opening '"'
             bool escape_next = false;
             while (ptr < s.size() && (escape_next || s[ptr] != '"')) {
-                escape_next = (s[ptr] == '\\');
+                // Repeated backslashes must be interpreted as pairs
+                escape_next = (s[ptr] == '\\' && !escape_next);
                 value.push_back(s[ptr]);
                 ++ptr;
             }
             if (ptr == s.size()) // unexpected end of line
                 return std::map<std::string,std::string>();
             ++ptr; // skip closing '"'
-            /* TODO: unescape value - according to the spec this depends on the
-             * context, some strings use C-LogPrintf style escape codes, some
-             * don't. So may be better handled at the call site.
+            /**
+             * Unescape value. Per https://spec.torproject.org/control-spec section 2.1.1:
+             *
+             *   For future-proofing, controller implementors MAY use the following
+             *   rules to be compatible with buggy Tor implementations and with
+             *   future ones that implement the spec as intended:
+             *
+             *     Read \n \t \r and \0 ... \377 as C escapes.
+             *     Treat a backslash followed by any other character as that character.
              */
+            std::string escaped_value;
+            for (size_t i = 0; i < value.size(); ++i) {
+                if (value[i] == '\\') {
+                    // This will always be valid, because if the QuotedString
+                    // ended in an odd number of backslashes, then the parser
+                    // would already have returned above, due to a missing
+                    // terminating double-quote.
+                    ++i;
+                    if (value[i] == 'n') {
+                        escaped_value.push_back('\n');
+                    } else if (value[i] == 't') {
+                        escaped_value.push_back('\t');
+                    } else if (value[i] == 'r') {
+                        escaped_value.push_back('\r');
+                    } else if ('0' <= value[i] && value[i] <= '7') {
+                        size_t j;
+                        // Octal escape sequences have a limit of three octal digits,
+                        // but terminate at the first character that is not a valid
+                        // octal digit if encountered sooner.
+                        for (j = 1; j < 3 && (i+j) < value.size() && '0' <= value[i+j] && value[i+j] <= '7'; ++j) {}
+                        // Tor restricts first digit to 0-3 for three-digit octals.
+                        // A leading digit of 4-7 would therefore be interpreted as
+                        // a two-digit octal.
+                        if (j == 3 && value[i] > '3') {
+                            j--;
+                        }
+                        escaped_value.push_back(strtol(value.substr(i, j).c_str(), NULL, 8));
+                        // Account for automatic incrementing at loop end
+                        i += j - 1;
+                    } else {
+                        escaped_value.push_back(value[i]);
+                    }
+                } else {
+                    escaped_value.push_back(value[i]);
+                }
+            }
+            value = escaped_value;
         } else { // Unquoted value. Note that values can contain '=' at will, just no spaces
             while (ptr < s.size() && s[ptr] != ' ') {
                 value.push_back(s[ptr]);