[Add] Start of base64 encode/decode routines. Not quite working yet.

src/base64.c

@@ -0,0 +1,105 @@
+#include <malloc.h>
+#include <string.h>
+#include <stdint.h>
+
+// Encode table.
+static const char cb64[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstu \
+                            vwxyz0123456789+/";
+// Decode table.
+static const char cd64[] = "|$$$}rstuvwxyz{$$$$$$$>?@ABCDEFGHIJKLMNOPQRSTUVW \
+                            $$$$$$XYZ[\\]^_'abcdefghijklmnopq";
+
+// Encode src of sz length storing the new length in len.
+char* base64_encode(int* len, char* src, size_t sz) {
+  char* r;
+  size_t i, c;
+  uint32_t n;
+  uint8_t ch[4], pad;
+
+  // Create r.
+  c = sz * 4 / 3 + sz % 3;
+  c += c / 76;
+  (*len) = c;
+  r = malloc((*len) * sizeof(char));
+
+  // Setup padding.
+  pad = sz % 3;
+
+  // Time to do the bulk of the work.
+  i = 0;
+  for(c = 0; c < sz; c += 3) {
+    // Specification wants newline after every 76 characters.
+    if((c > 0) && ((c / 3 * 4) % 76 == 0))
+      r[i++] = '\n';
+
+    // n is 24 bits.
+    n = (src[c] << 16) +
+      (c+1<sz) ? (src[c+1] << 8) : 0 +  // May be out of range.
+      (c+2<sz) ? src[c+2] : 0;          // May be out of range.
+
+    // ch[0-3] are 6 bits each.
+    ch[0] = (n >> 18) & 63;
+    ch[1] = (n >> 12) & 63;
+    ch[2] = (n >> 6)  & 63;
+    ch[3] = n         & 63;
+
+    r[i++] = cb64[ch[0]];
+    r[i++] = cb64[ch[1]];
+    r[i++] = cb64[ch[2]];
+    r[i++] = cb64[ch[3]];
+  }
+  
+  for(c = 0; c < pad; c++)
+    r[i++] = '=';
+  r[i] = '\0';
+
+  return r;
+}
+
+inline int dec_valid(char inp) {
+  if((inp < 43) || (inp > 122) || cd64[(int)inp-43] == '$')
+    return 0;
+  return 1;
+}
+
+inline char dec_ch(char inp) {
+  return cd64[(int)inp-43] - 61;
+}
+
+char* base64_decode(int* len, char* src, size_t sz) {
+  char* r, *dat;
+  size_t c, i, j;
+  uint32_t n;
+
+  // Allocate r.
+  c = sz * 3 / 4;
+  r = malloc(c * sizeof(char));
+
+  // Create a clean version of the text.
+  dat = malloc(sz * sizeof(char));
+  j = 0;
+  for(i = 0; i < sz; i++) {
+    if(src[i] == '=')
+      dat[j++] = '\0';
+    else if(dec_valid(src[i]))
+      dat[j++] = src[i];
+  }
+
+  // Fill r.
+  i = 0;
+  for(c = 0; c < j; c += 4) {
+    n = dec_ch(dat[c+0]) << 18;
+    n = dec_ch(dat[c+1]) << 12;
+    n = dec_ch(dat[c+2]) << 6;
+    n = dec_ch(dat[c+3]) << 0;
+
+    r[i++] = (n >> 16)  & 0xFF;
+    r[i++] = (n >> 8)   & 0xFF;
+    r[i++] = (n >> 0)   & 0xFF;
+
+  }
+
+  (*len) = i;
+  return r;
+}
+

src/base64.h

@@ -0,0 +1,5 @@
+#pragma once
+
+char* base64_encode(int* len, char* src, size_t sz);
+char* base64_decode(int* len, char* src, size_t sz);
+