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authorKaren Arutyunov <karen@codesynthesis.com>2016-04-25 12:39:27 +0300
committerKaren Arutyunov <karen@codesynthesis.com>2016-05-04 20:29:05 +0300
commit7806c39ecc92055cd338749148fda51b2dc01691 (patch)
treecb52f5bc766d12b68b9d20696aae0b60699ea43a /butl/base64.cxx
parentd20431e11290320f04d62e26b9a7cbcefaf5480c (diff)
Add base64_encode(), base64_decode()
Diffstat (limited to 'butl/base64.cxx')
-rw-r--r--butl/base64.cxx211
1 files changed, 211 insertions, 0 deletions
diff --git a/butl/base64.cxx b/butl/base64.cxx
new file mode 100644
index 0000000..2939b46
--- /dev/null
+++ b/butl/base64.cxx
@@ -0,0 +1,211 @@
+// file : butl/base64.cxx -*- C++ -*-
+// copyright : Copyright (c) 2014-2016 Code Synthesis Ltd
+// license : MIT; see accompanying LICENSE file
+
+#include <butl/base64>
+
+#include <cstddef> // size_t
+#include <istream>
+#include <ostream>
+#include <iterator> // {istreambuf, ostreambuf, back_insert}_iterator
+#include <stdexcept> // invalid_argument
+
+using namespace std;
+
+namespace butl
+{
+ static const char* codes =
+ "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
+
+ // base64-encode the data in the iterator range [i, e). Write the encoded
+ // data starting at the iterator position o.
+ //
+ template <typename I, typename O>
+ static void
+ base64_encode (I& i, const I& e, O& o)
+ {
+ const size_t un (65); // Non-existing index of the codes string.
+ for (size_t n (0); i != e; ++n)
+ {
+ if (n && n % 19 == 0)
+ *o++ = '\n'; // Split into lines, like the base64 utility does.
+
+ char c (*i++);
+ size_t i1 ((c >> 2) & 0x3F);
+ size_t i2 ((c << 4) & 0x30);
+
+ size_t i3 (un);
+ if (i != e)
+ {
+ c = *i++;
+ i2 |= (c >> 4) & 0xF;
+ i3 = (c << 2) & 0x3C;
+ }
+
+ size_t i4 (un);
+ if (i != e)
+ {
+ c = *i++;
+ i3 |= (c >> 6) & 0x3;
+ i4 = c & 0x3F;
+ }
+
+ *o++ = codes[i1];
+ *o++ = codes[i2];
+ *o++ = i3 == un ? '=' : codes[i3];
+ *o++ = i4 == un ? '=' : codes[i4];
+ }
+ }
+
+ static char
+ index (char c)
+ {
+ switch (c)
+ {
+ case '/': return 63;
+ case '+': return 62;
+ default:
+ {
+ if (c >= 'A' && c <= 'Z')
+ return c - 'A';
+ else if (c >= 'a' && c <= 'z')
+ return c - 'a' + 26;
+ else if (c >= '0' && c <= '9')
+ return c - '0' + 52;
+ else
+ throw invalid_argument ("invalid input");
+ }
+ }
+ }
+
+ // base64-decode the data in the iterator range [i, e). Write the decoded
+ // data starting at the iterator position o. Throw invalid_argument if the
+ // input data is invalid.
+ //
+ template <typename I, typename O>
+ static void
+ base64_decode (I& i, const I& e, O& o)
+ {
+ auto bad = []() {throw invalid_argument ("invalid input");};
+
+ auto next = [&i, &e, &bad]() -> char
+ {
+ if (i == e)
+ bad ();
+ return *i++;
+ };
+
+ while (i != e)
+ {
+ char c (next ());
+ if (c == '\n') // @@ Should we check for '\r' as well ?
+ continue;
+
+ char i1 = index (c);
+ char i2 = index (next ());
+ *o++ = (i1 << 2) | (i2 >> 4);
+
+ c = next ();
+ if (c == '=')
+ {
+ if (next () != '=' || i != e)
+ bad ();
+ }
+ else
+ {
+ char i3 = index (c);
+ *o++ = (i2 << 4) | (i3 >> 2);
+
+ c = next ();
+ if (c == '=')
+ {
+ if (i != e)
+ bad ();
+ }
+ else
+ *o++ = (i3 << 6) | index (c);
+ }
+ }
+ }
+
+ string
+ base64_encode (istream& is)
+ {
+ if (!is.good ())
+ throw invalid_argument ("bad stream");
+
+ string r;
+ istreambuf_iterator<char> i (is);
+ back_insert_iterator<string> o (r);
+
+ base64_encode (i, istreambuf_iterator<char> (), o);
+ is.setstate (istream::eofbit);
+ return r;
+ }
+
+ void
+ base64_encode (ostream& os, istream& is)
+ {
+ if (!os.good () || !is.good ())
+ throw invalid_argument ("bad stream");
+
+ istreambuf_iterator<char> i (is);
+ ostreambuf_iterator<char> o (os);
+ base64_encode (i, istreambuf_iterator<char> (), o);
+
+ if (o.failed ())
+ os.setstate (istream::badbit);
+
+ is.setstate (istream::eofbit);
+ }
+
+ std::string
+ base64_encode (const std::vector<char>& v)
+ {
+ string r;
+ back_insert_iterator<string> o (r);
+ auto i (v.begin ());
+ base64_encode (i, v.end (), o);
+ return r;
+ }
+
+ void
+ base64_decode (ostream& os, istream& is)
+ {
+ if (!os.good () || !is.good ())
+ throw invalid_argument ("bad stream");
+
+ istreambuf_iterator<char> i (is);
+ ostreambuf_iterator<char> o (os);
+ base64_decode (i, istreambuf_iterator<char> (), o);
+
+ if (o.failed ())
+ os.setstate (istream::badbit);
+
+ is.setstate (istream::eofbit);
+ }
+
+ void
+ base64_decode (ostream& os, const string& s)
+ {
+ if (!os.good ())
+ throw invalid_argument ("bad stream");
+
+ ostreambuf_iterator<char> o (os);
+ auto i (s.cbegin ());
+ base64_decode (i, s.cend (), o);
+
+ if (o.failed ())
+ os.setstate (istream::badbit);
+ }
+
+ vector<char>
+ base64_decode (const string& s)
+ {
+ vector<char> r;
+ back_insert_iterator<vector<char>> o (r);
+ auto i (s.cbegin ());
+ base64_decode (i, s.cend (), o);
+ return r;
+ }
+}