udhcp: fix DNS domanin codec bug: bad compression flag checks

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

diff --git a/networking/udhcp/domain_codec.c b/networking/udhcp/domain_codec.c
index c00b4ed884aa4b1f2f6c78af9367e837bd11b316..93dfd9a4e19c8c25f301e6c5df3ad26911b60ffe 100644 (file)
--- a/networking/udhcp/domain_codec.c
+++ b/networking/udhcp/domain_codec.c
@@ -44,14 +44,14 @@ char* FAST_FUNC dname_dec(const uint8_t *cstr, int clen, const char *pre)
                while (crtpos < clen) {
                        c = cstr + crtpos;
 
-                       if (*c & NS_CMPRSFLGS) {
+                       if ((*c & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
                                /* pointer */
                                if (crtpos + 2 > clen) /* no offset to jump to? abort */
                                        return NULL;
                                if (retpos == 0) /* toplevel? save return spot */
                                        retpos = crtpos + 2;
                                depth++;
-                               crtpos = ((c[0] & 0x3f) << 8) | (c[1] & 0xff); /* jump */
+                               crtpos = ((c[0] & 0x3f) << 8) | c[1]; /* jump */
                        } else if (*c) {
                                /* label */
                                if (crtpos + *c + 1 > clen) /* label too long? abort */
@@ -154,7 +154,7 @@ static int find_offset(const uint8_t *cstr, int clen, const uint8_t *dname)
        while (off < clen) {
                c = cstr + off;
 
-               if ((*c & NS_CMPRSFLGS) != 0) { /* pointer, skip */
+               if ((*c & NS_CMPRSFLGS) == NS_CMPRSFLGS) {      /* pointer, skip */
                        off += 2;
                } else if (*c) {        /* label, try matching dname */
                        inc = *c + 1;
@@ -164,8 +164,8 @@ static int find_offset(const uint8_t *cstr, int clen, const uint8_t *dname)
                                        return off;
                                d += *c + 1;
                                c += *c + 1;
-                               if ((*c & NS_CMPRSFLGS) != 0)   /* pointer, jump */
-                                       c = cstr + (((*c & 0x3f) << 8) | (*(c + 1) & 0xff));
+                               if ((*c & NS_CMPRSFLGS) == NS_CMPRSFLGS)  /* pointer, jump */
+                                       c = cstr + (((c[0] & 0x3f) << 8) | c[1]);
                        }
                        off += inc;
                } else {        /* null, skip */
@@ -196,7 +196,7 @@ uint8_t* FAST_FUNC dname_enc(const uint8_t *cstr, int clen, const char *src, int
        for (d = dname; *d != 0; d += *d + 1) {
                off = find_offset(cstr, clen, d);
                if (off >= 0) { /* found a match, add pointer and terminate string */
-                       *d++ = NS_CMPRSFLGS;
+                       *d++ = NS_CMPRSFLGS + (off >> 8);
                        *d = off;
                        break;
                }