base64: Rework base64decode to handle split encoded data correctly

1 files changed, 27 insertions, 41 deletions

diff --git a/src/base64.c b/src/base64.c
index 7870a79..ba8acca 100644
--- a/src/base64.c
+++ b/src/base64.c
@@ -28,7 +28,7 @@ static const signed char base64_table[256] = {
         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63,
-        52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1,
+        52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -2, -1, -1,
         -1,  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14,
         15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1,
         -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
@@ -71,38 +71,6 @@ size_t base64encode(char *outbuf, const unsigned char *buf, size_t size)
         return m;
 }
 
-static int base64decode_block(unsigned char *target, const char *data, size_t data_size)
-{
-        int w1,w2,w3,w4;
-        int i;
-        size_t n;
-
-        if (!data || (data_size <= 0)) {
-                return 0;
-        }
-
-        n = 0;
-        i = 0;
-        while (n < data_size-3) {
-                w1 = base64_table[(int)data[n]];
-                w2 = base64_table[(int)data[n+1]];
-                w3 = base64_table[(int)data[n+2]];
-                w4 = base64_table[(int)data[n+3]];
-
-                if (w2 >= 0) {
-                        target[i++] = (char)((w1*4 + (w2 >> 4)) & 255);
-                }
-                if (w3 >= 0) {
-                        target[i++] = (char)((w2*16 + (w3 >> 2)) & 255);
-                }
-                if (w4 >= 0) {
-                        target[i++] = (char)((w3*64 + w4) & 255);
-                }
-                n+=4;
-        }
-        return i;
-}
-
 unsigned char *base64decode(const char *buf, size_t *size)
 {
         if (!buf || !size) return NULL;
@@ -111,19 +79,37 @@ unsigned char *base64decode(const char *buf, size_t *size)
         unsigned char *outbuf = (unsigned char*)malloc((len/4)*3+3);
         const char *ptr = buf;
         int p = 0;
-        size_t l = 0;
+        int wv, w1, w2, w3, w4;
+        int tmpval[4];
+        int tmpcnt = 0;
 
         do {
-                ptr += strspn(ptr, "\r\n\t ");
+                while (ptr < buf+len && (*ptr == ' ' || *ptr == '\t' || *ptr == '\n' || *ptr == '\r')) {
+                        ptr++;
+                }
                 if (*ptr == '\0' || ptr >= buf+len) {
                         break;
                 }
-                l = strcspn(ptr, "\r\n\t ");
-                if (l > 3 && ptr+l <= buf+len) {
-                        p+=base64decode_block(outbuf+p, ptr, l);
-                        ptr += l;
-                } else {
-                        break;
+                if ((wv = base64_table[(int)(unsigned char)*ptr++]) == -1) {
+                        continue;
+                }
+                tmpval[tmpcnt++] = wv;
+                if (tmpcnt == 4) {
+                        tmpcnt = 0;
+                        w1 = tmpval[0];
+                        w2 = tmpval[1];
+                        w3 = tmpval[2];
+                        w4 = tmpval[3];
+
+                        if (w2 >= 0) {
+                                outbuf[p++] = (unsigned char)(((w1 << 2) + (w2 >> 4)) & 0xFF);
+                        }
+                        if (w3 >= 0) {
+                                outbuf[p++] = (unsigned char)(((w2 << 4) + (w3 >> 2)) & 0xFF);
+                        }
+                        if (w4 >= 0) {
+                                outbuf[p++] = (unsigned char)(((w3 << 6) + w4) & 0xFF);
+                        }
                 }
         } while (1);