Switch to web-safe base64 encoding

The decoder still supports standard base64 encoding for backwards
compatibility.

src/sso/base64.c

@@ -34,16 +34,16 @@ static const unsigned char base64_enc_map[64] = {
     'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
     'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
     'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
-    '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/'};
+    '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '-', '_'};
 
 static const unsigned char base64_dec_map[128] = {
     127, 127, 127, 127, 127, 127, 127, 127, 127, 127, 127, 127, 127, 127, 127,
     127, 127, 127, 127, 127, 127, 127, 127, 127, 127, 127, 127, 127, 127, 127,
     127, 127, 127, 127, 127, 127, 127, 127, 127, 127, 127, 127, 127, 62,  127,
-    127, 127, 63,  52,  53,  54,  55,  56,  57,  58,  59,  60,  61,  127, 127,
+    62,  127, 63,  52,  53,  54,  55,  56,  57,  58,  59,  60,  61,  127, 127,
     127, 64,  127, 127, 127, 0,   1,   2,   3,   4,   5,   6,   7,   8,   9,
     10,  11,  12,  13,  14,  15,  16,  17,  18,  19,  20,  21,  22,  23,  24,
-    25,  127, 127, 127, 127, 127, 127, 26,  27,  28,  29,  30,  31,  32,  33,
+    25,  127, 127, 127, 127, 63,  127, 26,  27,  28,  29,  30,  31,  32,  33,
     34,  35,  36,  37,  38,  39,  40,  41,  42,  43,  44,  45,  46,  47,  48,
     49,  50,  51,  127, 127, 127, 127, 127};
 
@@ -64,8 +64,8 @@ size_t sso_base64_encode_size(size_t slen) {
   return n;
 }
 
-/*
- * Encode a buffer into base64 format
+/**
+ * Encode a buffer into "web-safe" base64 format
  */
 int sso_base64_encode(unsigned char *dst, size_t *dlen,
                       const unsigned char *src, size_t slen) {
@@ -117,8 +117,10 @@ int sso_base64_encode(unsigned char *dst, size_t *dlen,
   return 0;
 }
 
-/*
- * Decode a base64-formatted buffer
+/**
+ * Decode a base64-formatted buffer.
+ *
+ * Supports both standard and "web-safe" encodings.
  */
 int sso_base64_decode(unsigned char *dst, size_t *dlen,
                       const unsigned char *src, size_t slen) {

src/sso/test/sso_unittest.cc

@@ -8,25 +8,57 @@ extern "C" {
 
 namespace {
 
+static unsigned char alphabet[] = {
+  0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19,
+  20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36,
+  37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53,
+  54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70,
+  71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87,
+  88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103,
+  104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117,
+  118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131,
+  132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145,
+  146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159,
+  160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173,
+  174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187,
+  188, 189, 190, 191, 192, 193, 194, 195, 196, 197, 198, 199, 200, 201,
+  202, 203, 204, 205, 206, 207, 208, 209, 210, 211, 212, 213, 214, 215,
+  216, 217, 218, 219, 220, 221, 222, 223, 224, 225, 226, 227, 228, 229,
+  230, 231, 232, 233, 234, 235, 236, 237, 238, 239, 240, 241, 242, 243,
+  244, 245, 246, 247, 248, 249, 250, 251, 252, 253, 254, 255
+};
+
+static const std::string encoded_alphabet = "AAECAwQFBgcICQoLDA0ODxAREhMUFRYXGBkaGxwdHh8gISIjJCUmJygpKissLS4vMDEyMzQ1Njc4OTo7PD0-P0BBQkNERUZHSElKS0xNTk9QUVJTVFVWV1hZWltcXV5fYGFiY2RlZmdoaWprbG1ub3BxcnN0dXZ3eHl6e3x9fn-AgYKDhIWGh4iJiouMjY6PkJGSk5SVlpeYmZqbnJ2en6ChoqOkpaanqKmqq6ytrq-wsbKztLW2t7i5uru8vb6_wMHCw8TFxsfIycrLzM3Oz9DR0tPU1dbX2Nna29zd3t_g4eLj5OXm5-jp6uvs7e7v8PHy8_T19vf4-fr7_P3-_w==";
+
+static const std::string encoded_alphabet_std = "AAECAwQFBgcICQoLDA0ODxAREhMUFRYXGBkaGxwdHh8gISIjJCUmJygpKissLS4vMDEyMzQ1Njc4OTo7PD0+P0BBQkNERUZHSElKS0xNTk9QUVJTVFVWV1hZWltcXV5fYGFiY2RlZmdoaWprbG1ub3BxcnN0dXZ3eHl6e3x9fn+AgYKDhIWGh4iJiouMjY6PkJGSk5SVlpeYmZqbnJ2en6ChoqOkpaanqKmqq6ytrq+wsbKztLW2t7i5uru8vb6_wMHCw8TFxsfIycrLzM3Oz9DR0tPU1dbX2Nna29zd3t/g4eLj5OXm5+jp6uvs7e7v8PHy8/T19vf4+fr7/P3+/w==";
+
 TEST(Base64, EncodeOk) {
-  const char *in = "tests";
-  char out[128] = {0};
+  char out[512] = {0};
   size_t sz = sizeof(out);
-  EXPECT_EQ(0, sso_base64_encode((unsigned char *)out, &sz, (unsigned char *)in,
-                                 (size_t)strlen(in)));
-  EXPECT_EQ(8, int(sso_base64_encode_size((size_t)strlen(in))));
-  EXPECT_EQ(8, int(sz));
-  EXPECT_EQ("dGVzdHM=", std::string(out));
+  EXPECT_EQ(0, sso_base64_encode((unsigned char *)out, &sz, alphabet, 256));
+  EXPECT_EQ(344, int(sso_base64_encode_size(256)));
+  EXPECT_EQ(344, int(sz));
+  EXPECT_EQ(encoded_alphabet, std::string(out));
 }
 
 TEST(Base64, DecodeOk) {
-  char in[] = "dGVzdHM=";
-  char out[128] = {0};
+  const char *in = encoded_alphabet.c_str();
+  char out[256] = {0};
+  size_t sz = sizeof(out);
+  EXPECT_EQ(0, sso_base64_decode((unsigned char *)out, &sz, (unsigned char *)in,
+                                 (size_t)strlen(in)));
+  EXPECT_EQ(256, int(sz));
+  EXPECT_EQ(0, memcmp(alphabet, out, sz));
+}
+
+TEST(Base64, DecodeStdOk) {
+  const char *in = encoded_alphabet_std.c_str();
+  char out[256] = {0};
   size_t sz = sizeof(out);
   EXPECT_EQ(0, sso_base64_decode((unsigned char *)out, &sz, (unsigned char *)in,
                                  (size_t)strlen(in)));
-  EXPECT_EQ(5, int(sz));
-  EXPECT_EQ("tests", std::string(out));
+  EXPECT_EQ(256, int(sz));
+  EXPECT_EQ(0, memcmp(alphabet, out, sz));
 }
 
 class SSO : public testing::Test {