XDP blog, post 1 gist 3

xdpblog1-3-parse_dname.c

static __always_inline
uint8_t *parse_dname(struct cursor *c, uint8_t *pkt)
{
        uint8_t *dname = c->pos;
 
        int  i;
        for (i = 0; i < 128; i++) { /* Maximum 128 labels */
                uint8_t o;
 
                if (c->pos + 1 > c->end)
                        return 0;
 
                o = *(uint8_t *)c->pos;
                if ((o & 0xC0) == 0xC0) {
                        /* Compression label, Only back references! */
                        if ((o | 0x3F) >= (dname - pkt))
                                return 0;
 
                        /* Compression label is the last label of a dname. */
                        c->pos += 1;
                        break;
 
                } else if (o & 0xC0)
                        /* Unknown label type */
                        return 0;
 
                c->pos += o + 1;
                if (!o)
                        break;
        }
        return dname;
}

Should be o & 0x3F on line 16.