From 26d1f221761ba264906f215ed53f4f57ab0f9d06 Mon Sep 17 00:00:00 2001
From: Tslil Clingman <hiato1@gmail.com>
Date: Thu, 25 Jun 2015 02:51:02 +0200
Subject: Init

---
 base64.c | 153 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 153 insertions(+)
 create mode 100644 base64.c

(limited to 'base64.c')

diff --git a/base64.c b/base64.c
new file mode 100644
index 0000000..b5fecff
--- /dev/null
+++ b/base64.c
@@ -0,0 +1,153 @@
+/*
+  This file is part of msr.
+
+  msr is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+  
+  msr 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 GNU General Public
+  License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with Foobar. If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "base64.h"
+
+static const char b64padchar = (uint8_t)'=';
+static const char b64chars[65] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
+
+/*
+;; Precompute inverse lookup with skippable stuff and padding
+(insert
+ (apply #'concat
+        (let ((str "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/")
+              (skip " \t\n\r") (skipnum 65)
+              (pad ?=) (padnum 64) (invalidnum 66))
+          (cl-loop for k from 0 to 255
+                   for j = (let* ((s (char-to-string k))
+                                  (v (s-index-of s str))
+                                  (w (s-index-of s skip))
+                                  (x (char-equal k pad)))
+                             (if v (format "%2dU " v)
+                                (if w "SKIP"
+                                  (if x "PADD" "INVD"))))
+                   collect (concat ", " j)))))
+*/
+#define INVD (uint8_t)66
+#define SKIP (uint8_t)65
+#define PADD (uint8_t)64
+static const uint8_t b64inverse[256] = {
+  INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, SKIP, SKIP, INVD, INVD, SKIP, INVD, INVD,
+  INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD,
+  SKIP, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, 62  , INVD, INVD, INVD, 63 ,
+  52  , 53  , 54  , 55  , 56  , 57  , 58  , 59  , 60  , 61  , INVD, INVD, INVD, PADD, INVD, INVD,
+  INVD,  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  , INVD, INVD, INVD, INVD, INVD,
+  INVD, 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  , INVD, INVD, INVD, INVD, INVD,
+  INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD,
+  INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD,
+  INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD,
+  INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD,
+  INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD,
+  INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD,
+  INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD,
+  INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD
+};
+
+Error bin_to_base64(uint8_t const * const bin, size_t binlen,
+                    uint8_t *out, size_t maxoutsize, size_t *outlen) {
+  if ((*outlen = 4*(binlen/3)+4) > maxoutsize) return E_SMALL_BUFF;
+  size_t k, l;
+  uint32_t n = 0;
+  // Look at floor(binlen/3) groups of three bytes
+  for (k=0, l=0; k<binlen/3; k++) {
+    n = ((uint32_t)bin[3*k])<<16;
+    n |= ((uint32_t)bin[3*k+1])<<8;
+    n |= ((uint32_t)bin[3*k+2]);
+    
+    out[l++] = b64chars[(n>>18)&63];
+    out[l++] = b64chars[(n>>12)&63];
+    out[l++] = b64chars[(n>>6)&63];
+    out[l++] = b64chars[n&63];
+  }
+  // What is the actual index in bin?
+  k *= 3;
+  // Now deal with remainders
+  if (k<binlen) {
+    n = ((uint32_t)bin[k])<<16;
+    out[l+3] = b64padchar;
+    if (k+1<binlen) {
+      n |= ((uint32_t)bin[k+1])<<8;
+      out[l+2] = b64chars[(n>>6)&63];
+    } else out[l+2] = b64padchar;
+    out[l] = b64chars[(n>>18)&63];
+    out[l+1] = b64chars[(n>>12)&63];
+    l+=4;
+  };
+  out[l]=0;
+  return SUCCESS;
+}
+
+// Note: will read first valid b64 encoded string and stop caring
+Error base64_to_bin(uint8_t const * const str, size_t strlen,
+                    uint8_t *buf, size_t bufmaxsize, size_t *buflen) {
+  if (str == NULL) return E_NULL;
+  *buflen = 0;
+  size_t k = 0;
+  uint8_t c = 0;
+  uint32_t t = 0;
+  while(k<strlen) {
+    uint8_t l = b64inverse[str[k++]];
+    switch (l) {
+        // Skip = Skip, a universal truth
+      case SKIP: break;
+        // We don't take these transgressions lightly
+      case INVD: return E_B64_BAD_STR;
+        // Annoying validity checks here
+      case PADD: {
+        if (c<2) return E_B64_BAD_STR;
+        // If we have only consumed 2/4 chars, then there must be 2 x pad || .* || eof
+        if (c==2 && ( str[k]!=b64padchar))
+          return E_B64_BAD_STR;
+        k = strlen;
+        // If we have 3/4 chars, pad || .* || eof
+        break;
+      }
+        // A valid b64 char (not incl. padding)
+      default: {
+        // Store these six bits
+        t = (t<<6) | l;
+        // If we've done this four times, then output three bytes
+        if (++c > 3) {
+          if ((*buflen)>=bufmaxsize) return E_SMALL_BUFF;
+          buf[(*buflen)++] = (uint8_t)((t>>16)&255);
+          if ((*buflen)>=bufmaxsize) return E_SMALL_BUFF;
+          buf[(*buflen)++] = (uint8_t)((t>>8)&255);
+          if ((*buflen)>=bufmaxsize) return E_SMALL_BUFF;
+          buf[(*buflen)++] = (uint8_t)(t&255);
+          c = t = 0;
+        }
+      }
+    }
+  }
+  // This should not happen
+  if (c==1) return E_B64_BAD_STR;
+  // Finish up, c=2 => 1 byte, c=3 => 2 bytes
+  else if (c==2) {
+    if ((*buflen)>=bufmaxsize) return E_SMALL_BUFF;
+    buf[(*buflen)++] = (uint8_t)((t>>4)&255);
+  }
+  else if (c==3) {
+    if ((*buflen)>=bufmaxsize) return E_SMALL_BUFF;
+    buf[(*buflen)++] = (uint8_t)((t>>10)&255);
+    if ((*buflen)>=bufmaxsize) return E_SMALL_BUFF;
+    buf[(*buflen)++] = (uint8_t)((t>>2)&255);
+  }
+  // done
+  return SUCCESS;
+}
-- 
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