X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=base64.c;h=122465f8feea79cf06d09bfd759d2446ee0f3f12;hp=4809a2f285f63dd83132f693be23f68945fce21d;hb=23ef2355fbdebce56083ec7a0ebb65a05c42e5dc;hpb=35fcd604e2ec04f8667c85fa1552932b1a0e6efb

diff --git a/base64.c b/base64.c
index 4809a2f2..122465f8 100644
--- a/base64.c
+++ b/base64.c
@@ -13,13 +13,45 @@
 #include "base64.h"
 #include "string.h"
 
-static const char Base64[] =
-	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
-static const char Pad64 = '=';
+static const unsigned char base64_tab[256] = {
+	255, 255, 255, 255, 255, 255, 255, 255, /* 00-07 */
+	255, 255, 255, 255, 255, 255, 255, 255, /* 08-0f */
+	255, 255, 255, 255, 255, 255, 255, 255, /* 10-17 */
+	255, 255, 255, 255, 255, 255, 255, 255, /* 18-1f */
+	255, 255, 255, 255, 255, 255, 255, 255, /* 20-2f */
+	255, 255, 255,  62, 255, 255, 255,  63, /* 28-2f */
+	52 ,  53,  54,  55,  56,  57,  58,  59, /* 30-37 */
+	60 ,  61, 255, 255, 255, 255, 255, 255, /* 38-3f */
+	255,   0,   1,   2,   3,   4,   5,   6, /* 40-47 */
+	7  ,   8,   9,  10,  11,  12,  13,  14, /* 48-4f */
+	15 ,  16,  17,  18,  19,  20,  21,  22, /* 50-57 */
+	23 ,  24,  25, 255, 255, 255, 255, 255, /* 58-5f */
+	255,  26,  27,  28,  29,  30,  31,  32, /* 60-6f */
+	33 ,  34,  35,  36,  37,  38,  39,  40, /* 68-6f */
+	41 ,  42,  43,  44,  45,  46,  47,  48, /* 70-77 */
+	49 ,  50,  51, 255, 255, 255, 255, 255, /* 78-7f */
+	255, 255, 255, 255, 255, 255, 255, 255, /* 80-87 */
+	255, 255, 255, 255, 255, 255, 255, 255, /* 88-8f */
+	255, 255, 255, 255, 255, 255, 255, 255, /* 90-97 */
+	255, 255, 255, 255, 255, 255, 255, 255, /* 98-9f */
+	255, 255, 255, 255, 255, 255, 255, 255, /* a0-a7 */
+	255, 255, 255, 255, 255, 255, 255, 255, /* a8-af */
+	255, 255, 255, 255, 255, 255, 255, 255, /* b0-b7 */
+	255, 255, 255, 255, 255, 255, 255, 255, /* b8-bf */
+	255, 255, 255, 255, 255, 255, 255, 255, /* c0-c7 */
+	255, 255, 255, 255, 255, 255, 255, 255, /* c8-cf */
+	255, 255, 255, 255, 255, 255, 255, 255, /* d0-d7 */
+	255, 255, 255, 255, 255, 255, 255, 255, /* d8-df */
+	255, 255, 255, 255, 255, 255, 255, 255, /* e0-e7 */
+	255, 255, 255, 255, 255, 255, 255, 255, /* e8-ef */
+	255, 255, 255, 255, 255, 255, 255, 255, /* f0-f7 */
+	255, 255, 255, 255, 255, 255, 255, 255, /* f8-ff */
+};
 
 /** Maximal possible size of the decoded data. */
 #define BASE64_MAX_DECODED_SIZE(_encoded_size) ((_encoded_size) / 4 * 3)
 
+#define PAD64 '='
 /**
  * base64-decode a buffer.
  *
@@ -41,106 +73,85 @@ static const char Pad64 = '=';
 int base64_decode(char const *src, size_t encoded_size, char **result,
 		size_t *decoded_size)
 {
-	unsigned int tarindex, state;
-	int ch;
-	char *pos;
-	const char *end = src + encoded_size;
-	unsigned char *target;
-	size_t targsize;
+	size_t i, j, state; /* source/target indices */
+	const char *end = src + encoded_size, *p;
+	unsigned char *target, uch;
 
 	if (encoded_size == (size_t)-1)
 		encoded_size = strlen(src);
-	targsize = BASE64_MAX_DECODED_SIZE(encoded_size);
-	target = para_malloc(targsize + 1);
-
-	state = 0;
-	tarindex = 0;
-
-	while (src < end) {
-		ch = *src++;
-		if (para_isspace(ch)) /* Skip whitespace anywhere. */
+	target = para_malloc(BASE64_MAX_DECODED_SIZE(encoded_size) + 1);
+
+	for (
+		i = 0, j = 0, state = 0;
+		i < encoded_size && (uch = src[i]) != '\0';
+		i++
+	) {
+		if (para_isspace(uch)) /* Skip whitespace anywhere. */
 			continue;
-
-		if (ch == Pad64)
+		if (uch == PAD64)
 			break;
-
-		pos = strchr(Base64, ch);
-		if (pos == NULL) /* A non-base64 character. */
+		if (base64_tab[uch] == 255) /* A non-base64 character. */
 			goto fail;
-
+		uch = base64_tab[uch];
 		switch (state) {
 		case 0:
-			if (tarindex >= targsize)
-				goto fail;
-			target[tarindex] = (pos - Base64) << 2;
-			state = 1;
+			target[j] = uch << 2;
 			break;
 		case 1:
-			if (tarindex + 1 >= targsize)
-				goto fail;
-			target[tarindex] |= (pos - Base64) >> 4;
-			target[tarindex + 1] = ((pos - Base64) & 0x0f) << 4;
-			tarindex++;
-			state = 2;
+			target[j] |= uch >> 4;
+			j++;
+			target[j] = (uch & 0x0f) << 4;
 			break;
 		case 2:
-			if (tarindex + 1 >= targsize)
-				goto fail;
-			target[tarindex] |= (pos - Base64) >> 2;
-			target[tarindex + 1] = ((pos - Base64) & 0x03) << 6;
-			tarindex++;
-			state = 3;
+			target[j] |= uch >> 2;
+			j++;
+			target[j] = (uch & 0x03) << 6;
 			break;
 		case 3:
-			if (tarindex >= targsize)
-				goto fail;
-			target[tarindex] |= pos - Base64;
-			tarindex++;
-			state = 0;
+			target[j] |= uch;
+			j++;
 			break;
 		}
+		state = (state + 1) % 4;
 	}
-
+	p = (i < encoded_size)? src + i : NULL;
 	/*
 	 * We are done decoding Base-64 chars.  Let's see if we ended
 	 * on a byte boundary, and/or with erroneous trailing characters.
 	 */
-
-	if (*src == Pad64) {		/* We got a pad char. */
-		ch = *src++;		/* Skip it, get next. */
+	if (p && *p == PAD64) { /* We got a pad char. Skip it, get next. */
+		p++;
 		switch (state) {
-		case 0:		/* Invalid = in first position */
-		case 1:		/* Invalid = in second position */
+		case 0: /* Invalid = in first position */
+		case 1: /* Invalid = in second position */
 			goto fail;
 
-		case 2:		/* Valid, means one byte of info */
+		case 2: /* Valid, means one byte of info */
 			/* Skip any number of spaces. */
-			for (; ch != '\0'; ch = *src++)
-				if (!isspace(ch))
+			for (; p < end && *p != '\0'; p++)
+				if (!para_isspace(*p))
 					break;
 			/* Make sure there is another trailing = sign. */
-			if (ch != Pad64)
+			if (*p != PAD64)
 				goto fail;
-			ch = *src++;		/* Skip the = */
 			/* Fall through to "single trailing =" case. */
-			/* FALLTHROUGH */
+			p++;
 
-		case 3:		/* Valid, means two bytes of info */
+		case 3: /* Valid, means two bytes of info */
 			/*
 			 * We know this char is an =.  Is there anything but
 			 * whitespace after it?
 			 */
-			for (; ch != '\0'; ch = *src++)
-				if (!isspace(ch))
+			for (; p < end && *p != '\0'; p++)
+				if (!para_isspace(*p))
 					goto fail;
-
 			/*
 			 * 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[tarindex] != 0)
+			if (target[j] != 0)
 				goto fail;
 		}
 	} else {
@@ -152,10 +163,10 @@ int base64_decode(char const *src, size_t encoded_size, char **result,
 			goto fail;
 	}
 	/* success */
-	target[tarindex] = '\0'; /* just to be sure */
-	*result = (char *)target;
+	target[j] = '\0'; /* just to be sure */
 	if (decoded_size)
-		*decoded_size = tarindex;
+		*decoded_size = j;
+	*result = (char *)target;
 	return 1;
 fail:
 	free(target);