Add base64 matcher functions

matcher/base64.c

@@ -0,0 +1,48 @@
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+
+static int B64Lookup(char x) {
+    if (x >= 0x41 && x <= 0x5a) {
+        return x-0x41;
+    } else if (x >= 0x61 && x <= 0x7a) {
+        return x-0x61+26;
+    } else if (x >= 0x30 && x <= 0x39) {
+        return x-0x30+52;
+    } else if (x == 0x2d) {
+        return 62;
+    } else if (x == 0x5f) {
+        return 63;
+    } else {
+        return 0;
+    }
+}
+
+int B64DecodeURL(char* input, char** output) {
+    int b64len = strlen(input);
+    int output_len = (b64len/4) * 3;
+    char* buffer = malloc(output_len);
+
+    int count = 0;
+    for(int i=0; i<b64len; i+=4) {
+        uint32_t v = 0;
+        for(int j=0; j<4; j++) {
+            v = v << 6;
+            v += B64Lookup(input[i+j]);
+        }
+        buffer[count++] = (v >> 16);
+        buffer[count++] = (v >> 8) & 0xff;
+        buffer[count++] = v & 0xFF;
+    }
+    *output = buffer;
+
+    if (b64len > 0 && input[b64len-1] == '=') {
+        output_len--;
+    }
+    if (b64len > 1 && input[b64len-2] == '=') {
+        output_len--;
+    }
+
+
+    return output_len;
+}

matcher/base64.h

@@ -0,0 +1,6 @@
+#ifndef BASE64_H
+#define BASE64_H
+
+int B64DecodeURL(char* input, char** output);
+
+#endif