1 files changed, 70 insertions, 8 deletions

diff --git a/src/lib/base/String.cpp b/src/lib/base/String.cpp
index 1ab3623..adbb11d 100644
--- a/src/lib/base/String.cpp
+++ b/src/lib/base/String.cpp
@@ -1,11 +1,11 @@
 /*
  * barrier -- mouse and keyboard sharing utility
  * Copyright (C) 2014-2016 Symless Ltd.
- * 
+ *
  * This package is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
  * found in the file LICENSE that should have accompanied this file.
- * 
+ *
  * This package is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
@@ -35,6 +35,42 @@
 namespace barrier {
 namespace string {
 
+namespace {
+
+// returns negative in case of non-matching character
+int hex_to_number(char ch)
+{
+    switch (ch) {
+        case '0': return 0;
+        case '1': return 1;
+        case '2': return 2;
+        case '3': return 3;
+        case '4': return 4;
+        case '5': return 5;
+        case '6': return 6;
+        case '7': return 7;
+        case '8': return 8;
+        case '9': return 9;
+
+        case 'a': return 10;
+        case 'b': return 11;
+        case 'c': return 12;
+        case 'd': return 13;
+        case 'e': return 14;
+        case 'f': return 15;
+
+        case 'A': return 10;
+        case 'B': return 11;
+        case 'C': return 12;
+        case 'D': return 13;
+        case 'E': return 14;
+        case 'F': return 15;
+    }
+    return -1;
+}
+
+} // namespace
+
 std::string
 format(const char* fmt, ...)
 {
@@ -135,7 +171,7 @@ sprintf(const char* fmt, ...)
         // try printing into the buffer
         va_list args;
         va_start(args, fmt);
-        int n = ARCH->vsnprintf(buffer, len, fmt, args);
+        int n = std::vsnprintf(buffer, len, fmt, args);
         va_end(args);
 
         // if the buffer wasn't big enough then make it bigger and try again
@@ -185,16 +221,42 @@ removeFileExt(std::string filename)
     return filename.substr(0, dot);
 }
 
-void
-toHex(std::string& subject, int width, const char fill)
+std::string to_hex(const std::vector<std::uint8_t>& subject, int width, const char fill)
 {
     std::stringstream ss;
     ss << std::hex;
-    for (unsigned int i = 0; i < subject.length(); i++) {
-        ss << std::setw(width) << std::setfill(fill) << (int)(unsigned char)subject[i];
+    for (unsigned int i = 0; i < subject.size(); i++) {
+        ss << std::setw(width) << std::setfill(fill) << static_cast<int>(subject[i]);
     }
 
-    subject = ss.str();
+    return ss.str();
+}
+
+std::vector<std::uint8_t> from_hex(const std::string& data)
+{
+    std::vector<std::uint8_t> result;
+    result.reserve(data.size() / 2);
+
+    std::size_t i = 0;
+    while (i < data.size()) {
+        if (data[i] == ':') {
+            i++;
+            continue;
+        }
+
+        if (i + 2 > data.size()) {
+            return {}; // uneven character count follows, it's unclear how to interpret it
+        }
+
+        auto high = hex_to_number(data[i]);
+        auto low = hex_to_number(data[i + 1]);
+        if (high < 0 || low < 0) {
+            return {};
+        }
+        result.push_back(high * 16 + low);
+        i += 2;
+    }
+    return result;
 }
 
 void