Pierre Chifflier wrote: > I am not very familiar with these kind of problems (alignment). If I > understand correctly, what I need to avoid is playing with pointers on a > buffer, especially if trying to read a structure. > > Since what I am trying to read is formatted as following: > > marker (uint32) > total_size (uint16) > payload_length (uint16) > payload (struct iphdr) This looks fine. Your input buffer should be suitably aligned by the allocator and these members are all well-aligned themselves. > Followed by a sequence of > option_id (uint16) > option_length (uint16) > option_value (variable, equal to option_length) > Am I right to assume that: > - I can define a (packed) structure for the first part, and that I can > set the pointer on the data buffer which was allocated by malloc > without problems ? [*] You don't even need packing. > - For the second part, there are 2 cases: > + integers must be read byte per byte > + strings can be used directly ? Assuming integers do not exceed 32 bit, just make sure the entire sequence is aligned to a multiple of four (which it is for the first entry, further ones need to use padding). -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
