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authorTom Gundersen <teg@jklm.no>2015-07-10 14:38:19 +0200
committerTom Gundersen <teg@jklm.no>2015-07-12 19:24:14 +0200
commit13a5d76b3277a2a499345cc24facc21eb17ccdae (patch)
treee3a06b0243983cc5c65bb3a3fdbba72455dd2e21 /src/basic/util.c
parent30494563f235b21c6583f7476b8ee35e9f5f8048 (diff)
basic: util - add base64mem() function similar to hexmem()
This implements RFC4648 for a slightly more compact representation of binary data compared to hex (6 bits per character rather than 4).
Diffstat (limited to 'src/basic/util.c')
-rw-r--r--src/basic/util.c174
1 files changed, 174 insertions, 0 deletions
diff --git a/src/basic/util.c b/src/basic/util.c
index 61dd6c4227..bc917ae574 100644
--- a/src/basic/util.c
+++ b/src/basic/util.c
@@ -954,6 +954,180 @@ int unhexmem(const char *p, size_t l, void **mem, size_t *len) {
return 0;
}
+/* https://tools.ietf.org/html/rfc4648#section-4 */
+char base64char(int x) {
+ static const char table[64] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+ "abcdefghijklmnopqrstuvwxyz"
+ "0123456789+/";
+ return table[x & 63];
+}
+
+int unbase64char(char c) {
+ unsigned offset;
+
+ if (c >= 'A' && c <= 'Z')
+ return c - 'A';
+
+ offset = 'Z' - 'A' + 1;
+
+ if (c >= 'a' && c <= 'z')
+ return c - 'a' + offset;
+
+ offset += 'z' - 'a' + 1;
+
+ if (c >= '0' && c <= '9')
+ return c - '0' + offset;
+
+ offset += '9' - '0' + 1;
+
+ if (c == '+')
+ return offset;
+
+ offset ++;
+
+ if (c == '/')
+ return offset;
+
+ return -EINVAL;
+}
+
+char *base64mem(const void *p, size_t l) {
+ char *r, *z;
+ const uint8_t *x;
+
+ /* three input bytes makes four output bytes, padding is added so we must round up */
+ z = r = malloc(4 * (l + 2) / 3 + 1);
+ if (!r)
+ return NULL;
+
+ for (x = p; x < (const uint8_t*) p + (l / 3) * 3; x += 3) {
+ /* x[0] == XXXXXXXX; x[1] == YYYYYYYY; x[2] == ZZZZZZZZ */
+ *(z++) = base64char(x[0] >> 2); /* 00XXXXXX */
+ *(z++) = base64char((x[0] & 3) << 4 | x[1] >> 4); /* 00XXYYYY */
+ *(z++) = base64char((x[1] & 15) << 2 | x[2] >> 6); /* 00YYYYZZ */
+ *(z++) = base64char(x[2] & 63); /* 00ZZZZZZ */
+ }
+
+ switch (l % 3) {
+ case 2:
+ *(z++) = base64char(x[0] >> 2); /* 00XXXXXX */
+ *(z++) = base64char((x[0] & 3) << 4 | x[1] >> 4); /* 00XXYYYY */
+ *(z++) = base64char((x[1] & 15) << 2); /* 00YYYY00 */
+ *(z++) = '=';
+
+ break;
+ case 1:
+ *(z++) = base64char(x[0] >> 2); /* 00XXXXXX */
+ *(z++) = base64char((x[0] & 3) << 4); /* 00XX0000 */
+ *(z++) = '=';
+ *(z++) = '=';
+
+ break;
+ }
+
+ *z = 0;
+ return r;
+}
+
+int unbase64mem(const char *p, size_t l, void **mem, size_t *_len) {
+ _cleanup_free_ uint8_t *t = NULL;
+ int a, b, c, d;
+ uint8_t *r, *z;
+ const char *x;
+ size_t len;
+
+ assert(p);
+
+ /* padding ensures any base63 input has input divisible by 4 */
+ if (l % 4 != 0)
+ return -EINVAL;
+
+ /* strip the padding */
+ if (l > 0 && p[l - 1] == '=')
+ l --;
+ if (l > 0 && p[l - 1] == '=')
+ l --;
+
+ /* a group of four input bytes needs three output bytes, in case of
+ padding we need to add two or three extra bytes */
+ len = (l / 4) * 3 + (l % 4 ? (l % 4) - 1 : 0);
+
+ z = r = malloc(len + 1);
+ if (!r)
+ return -ENOMEM;
+
+ for (x = p; x < p + (l / 4) * 4; x += 4) {
+ /* a == 00XXXXXX; b == 00YYYYYY; c == 00ZZZZZZ; d == 00WWWWWW */
+ a = unbase64char(x[0]);
+ if (a < 0)
+ return -EINVAL;
+
+ b = unbase64char(x[1]);
+ if (b < 0)
+ return -EINVAL;
+
+ c = unbase64char(x[2]);
+ if (c < 0)
+ return -EINVAL;
+
+ d = unbase64char(x[3]);
+ if (d < 0)
+ return -EINVAL;
+
+ *(z++) = (uint8_t) a << 2 | (uint8_t) b >> 4; /* XXXXXXYY */
+ *(z++) = (uint8_t) b << 4 | (uint8_t) c >> 2; /* YYYYZZZZ */
+ *(z++) = (uint8_t) c << 6 | (uint8_t) d; /* ZZWWWWWW */
+ }
+
+ switch (l % 4) {
+ case 3:
+ a = unbase64char(x[0]);
+ if (a < 0)
+ return -EINVAL;
+
+ b = unbase64char(x[1]);
+ if (b < 0)
+ return -EINVAL;
+
+ c = unbase64char(x[2]);
+ if (c < 0)
+ return -EINVAL;
+
+ /* c == 00ZZZZ00 */
+ if (c & 3)
+ return -EINVAL;
+
+ *(z++) = (uint8_t) a << 2 | (uint8_t) b >> 4; /* XXXXXXYY */
+ *(z++) = (uint8_t) b << 4 | (uint8_t) c >> 2; /* YYYYZZZZ */
+
+ break;
+ case 2:
+ a = unbase64char(x[0]);
+ if (a < 0)
+ return -EINVAL;
+
+ b = unbase64char(x[1]);
+ if (b < 0)
+ return -EINVAL;
+
+ /* b == 00YY0000 */
+ if (b & 15)
+ return -EINVAL;
+
+ *(z++) = (uint8_t) a << 2 | (uint8_t) (b >> 4); /* XXXXXXYY */
+
+ break;
+ }
+
+ *z = 0;
+
+ *mem = r;
+ r = NULL;
+ *_len = len;
+
+ return 0;
+}
+
char octchar(int x) {
return '0' + (x & 7);
}