1 files changed, 108 insertions, 0 deletions
diff --git a/src/base64.c b/src/base64.c
new file mode 100644
index 0000000..0841aba
--- /dev/null
+++ b/src/base64.c
@@ -0,0 +1,108 @@
+/*
+ * Copyright (C) 2017 "IoT.bzh"
+ * Author: José Bollo <jose.bollo@iot.bzh>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+
+const char base64_variant_standard[] = "+/=";
+const char base64_variant_url[] = "-_=";
+const char base64_variant_trunc[] = "+/";
+const char base64_variant_url_trunc[] = "-_";
+
+static char eb64(int x, const char *variant)
+{
+	if (x < 52)
+		return (char)(x + (x < 26 ? 'A' : 'a'-26));
+	else
+		return x < 62 ? (char)(x + '0' - 52) : variant[x - 62];
+}
+
+char *base64_encode_array_variant(const char * const *args, size_t count, const char *variant)
+{
+	const char *v, *s;
+	char *buffer, c;
+	size_t i, j, n;
+	uint16_t x;
+
+	/* compute size and allocate */
+	i = n = 0;
+	while (n < count)
+		i += strlen(args[n++]);
+	buffer = malloc(5 + ((i / 3) << 2));
+	if (!buffer)
+		return NULL;
+
+	/* encode */
+	v = variant ? : base64_variant_standard;
+	n = 0;
+	j = 0;
+	x = 0;
+	while (n < count) {
+		s = args[n++];
+		c = s[i = 0];
+		while (c) {
+			x = (uint16_t)((uint16_t)(x << 8) | (uint16_t)(uint8_t)c);
+			switch (j & 3) {
+			case 0:
+				buffer[j++] = eb64((x >> 2) & 63, v);
+				break;
+			case 1:
+				buffer[j++] = eb64((x >> 4) & 63, v);
+				break;
+			case 2:
+				buffer[j++] = eb64((x >> 6) & 63, v);
+				buffer[j++] = eb64(x & 63, v);
+				break;
+			}
+			c = s[++i];
+		}
+	}
+
+	/* pad */
+	if (v[2]) {
+		switch (j & 3) {
+		case 1:
+			buffer[j++] = eb64((x << 4) & 63, v);
+			buffer[j++] = v[2];
+			buffer[j++] = v[2];
+			break;
+		case 2:
+			buffer[j++] = eb64((x << 2) & 63, v);
+			buffer[j++] = v[2];
+			break;
+		}
+	}
+
+	/* done */
+	buffer[j] = 0;
+	return buffer;
+}
+
+char *base64_encode_multi_variant(const char * const *args, const char *variant)
+{
+	size_t count;
+
+	for (count = 0 ; args[count] ; count++);
+	return base64_encode_array_variant(args, count, variant);
+}
+
+char *base64_encode_variant(const char *arg, const char *variant)
+{
+	return base64_encode_array_variant(&arg, !!arg, variant);
+}
+