Support b64_ntop(), b64_pton() (bsd-compat)

Signed-off-by: akater <nuclearspace@gmail.com>

1 files changed, 257 insertions, 0 deletions

diff --git a/libc/inet/resolv.c b/libc/inet/resolv.c
index c05f18980..ed2e0d2fa 100644
--- a/libc/inet/resolv.c
+++ b/libc/inet/resolv.c
@@ -3632,6 +3632,263 @@ void res_close(void)
 }
 #endif
 
+#ifdef __UCLIBC_HAS_BSD_B64_NTOP_B64_PTON__
+#define Assert(Cond) if (!(Cond)) abort()
+
+static const char Base64[] =
+	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
+static const char Pad64 = '=';
+
+/* (From RFC1521 and draft-ietf-dnssec-secext-03.txt)
+   The following encoding technique is taken from RFC 1521 by Borenstein
+   and Freed.  It is reproduced here in a slightly edited form for
+   convenience.
+
+   A 65-character subset of US-ASCII is used, enabling 6 bits to be
+   represented per printable character. (The extra 65th character, "=",
+   is used to signify a special processing function.)
+
+   The encoding process represents 24-bit groups of input bits as output
+   strings of 4 encoded characters. Proceeding from left to right, a
+   24-bit input group is formed by concatenating 3 8-bit input groups.
+   These 24 bits are then treated as 4 concatenated 6-bit groups, each
+   of which is translated into a single digit in the base64 alphabet.
+
+   Each 6-bit group is used as an index into an array of 64 printable
+   characters. The character referenced by the index is placed in the
+   output string.
+
+                         Table 1: The Base64 Alphabet
+
+      Value Encoding  Value Encoding  Value Encoding  Value Encoding
+          0 A            17 R            34 i            51 z
+          1 B            18 S            35 j            52 0
+          2 C            19 T            36 k            53 1
+          3 D            20 U            37 l            54 2
+          4 E            21 V            38 m            55 3
+          5 F            22 W            39 n            56 4
+          6 G            23 X            40 o            57 5
+          7 H            24 Y            41 p            58 6
+          8 I            25 Z            42 q            59 7
+          9 J            26 a            43 r            60 8
+         10 K            27 b            44 s            61 9
+         11 L            28 c            45 t            62 +
+         12 M            29 d            46 u            63 /
+         13 N            30 e            47 v
+         14 O            31 f            48 w         (pad) =
+         15 P            32 g            49 x
+         16 Q            33 h            50 y
+
+   Special processing is performed if fewer than 24 bits are available
+   at the end of the data being encoded.  A full encoding quantum is
+   always completed at the end of a quantity.  When fewer than 24 input
+   bits are available in an input group, zero bits are added (on the
+   right) to form an integral number of 6-bit groups.  Padding at the
+   end of the data is performed using the '=' character.
+
+   Since all base64 input is an integral number of octets, only the
+         -------------------------------------------------
+   following cases can arise:
+
+       (1) the final quantum of encoding input is an integral
+           multiple of 24 bits; here, the final unit of encoded
+	   output will be an integral multiple of 4 characters
+	   with no "=" padding,
+       (2) the final quantum of encoding input is exactly 8 bits;
+           here, the final unit of encoded output will be two
+	   characters followed by two "=" padding characters, or
+       (3) the final quantum of encoding input is exactly 16 bits;
+           here, the final unit of encoded output will be three
+	   characters followed by one "=" padding character.
+   */
+
+int
+b64_ntop(u_char const *src, size_t srclength, char *target, size_t targsize) {
+	size_t datalength = 0;
+	u_char input[3];
+	u_char output[4];
+	size_t i;
+
+	while (2 < srclength) {
+		input[0] = *src++;
+		input[1] = *src++;
+		input[2] = *src++;
+		srclength -= 3;
+
+		output[0] = input[0] >> 2;
+		output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
+		output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
+		output[3] = input[2] & 0x3f;
+		Assert(output[0] < 64);
+		Assert(output[1] < 64);
+		Assert(output[2] < 64);
+		Assert(output[3] < 64);
+
+		if (datalength + 4 > targsize)
+			return (-1);
+		target[datalength++] = Base64[output[0]];
+		target[datalength++] = Base64[output[1]];
+		target[datalength++] = Base64[output[2]];
+		target[datalength++] = Base64[output[3]];
+	}
+
+	/* Now we worry about padding. */
+	if (0 != srclength) {
+		/* Get what's left. */
+		input[0] = input[1] = input[2] = '\0';
+		for (i = 0; i < srclength; i++)
+			input[i] = *src++;
+
+		output[0] = input[0] >> 2;
+		output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
+		output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
+		Assert(output[0] < 64);
+		Assert(output[1] < 64);
+		Assert(output[2] < 64);
+
+		if (datalength + 4 > targsize)
+			return (-1);
+		target[datalength++] = Base64[output[0]];
+		target[datalength++] = Base64[output[1]];
+		if (srclength == 1)
+			target[datalength++] = Pad64;
+		else
+			target[datalength++] = Base64[output[2]];
+		target[datalength++] = Pad64;
+	}
+	if (datalength >= targsize)
+		return (-1);
+	target[datalength] = '\0';	/* Returned value doesn't count \0. */
+	return (datalength);
+}
+/* libc_hidden_def (b64_ntop) */
+
+/* skips all whitespace anywhere.
+   converts characters, four at a time, starting at (or after)
+   src from base - 64 numbers into three 8 bit bytes in the target area.
+   it returns the number of data bytes stored at the target, or -1 on error.
+ */
+
+int
+b64_pton (char const *src, u_char *target, size_t targsize)
+{
+	int tarindex, state, ch;
+	char *pos;
+
+	state = 0;
+	tarindex = 0;
+
+	while ((ch = *src++) != '\0') {
+		if (isspace(ch))	/* Skip whitespace anywhere. */
+			continue;
+
+		if (ch == Pad64)
+			break;
+
+		pos = strchr(Base64, ch);
+		if (pos == 0) 		/* A non-base64 character. */
+			return (-1);
+
+		switch (state) {
+		case 0:
+			if (target) {
+				if ((size_t)tarindex >= targsize)
+					return (-1);
+				target[tarindex] = (pos - Base64) << 2;
+			}
+			state = 1;
+			break;
+		case 1:
+			if (target) {
+				if ((size_t)tarindex + 1 >= targsize)
+					return (-1);
+				target[tarindex]   |=  (pos - Base64) >> 4;
+				target[tarindex+1]  = ((pos - Base64) & 0x0f)
+							<< 4 ;
+			}
+			tarindex++;
+			state = 2;
+			break;
+		case 2:
+			if (target) {
+				if ((size_t)tarindex + 1 >= targsize)
+					return (-1);
+				target[tarindex]   |=  (pos - Base64) >> 2;
+				target[tarindex+1]  = ((pos - Base64) & 0x03)
+							<< 6;
+			}
+			tarindex++;
+			state = 3;
+			break;
+		case 3:
+			if (target) {
+				if ((size_t)tarindex >= targsize)
+					return (-1);
+				target[tarindex] |= (pos - Base64);
+			}
+			tarindex++;
+			state = 0;
+			break;
+		default:
+			abort();
+		}
+	}
+
+	/*
+	 * We are done decoding Base-64 chars.  Let's see if we ended
+	 * on a byte boundary, and/or with erroneous trailing characters.
+	 */
+
+	if (ch == Pad64) {		/* We got a pad char. */
+		ch = *src++;		/* Skip it, get next. */
+		switch (state) {
+		case 0:		/* Invalid = in first position */
+		case 1:		/* Invalid = in second position */
+			return (-1);
+
+		case 2:		/* Valid, means one byte of info */
+			/* Skip any number of spaces. */
+			for ((void)NULL; ch != '\0'; ch = *src++)
+				if (!isspace(ch))
+					break;
+			/* Make sure there is another trailing = sign. */
+			if (ch != Pad64)
+				return (-1);
+			ch = *src++;		/* Skip the = */
+			/* Fall through to "single trailing =" case. */
+			/* FALLTHROUGH */
+
+		case 3:		/* Valid, means two bytes of info */
+			/*
+			 * We know this char is an =.  Is there anything but
+			 * whitespace after it?
+			 */
+			for ((void)NULL; ch != '\0'; ch = *src++)
+				if (!isspace(ch))
+					return (-1);
+
+			/*
+			 * Now make sure for cases 2 and 3 that the "extra"
+			 * bits that slopped past the last full byte were
+			 * zeros.  If we don't check them, they become a
+			 * subliminal channel.
+			 */
+			if (target && target[tarindex] != 0)
+				return (-1);
+		}
+	} else {
+		/*
+		 * We ended by seeing the end of the string.  Make sure we
+		 * have no partial bytes lying around.
+		 */
+		if (state != 0)
+			return (-1);
+	}
+
+	return (tarindex);
+}
+#endif
+
 /* This needs to be after the use of _res in res_init, above.  */
 #undef _res