On 2016-08-08 at 21:04:20 +0200, Vadim Kochan <vadi...@gmail.com> wrote: > On Sat, Aug 06, 2016 at 01:36:26AM +0300, Vadim Kochan wrote: > > On Wed, Aug 03, 2016 at 04:27:14PM +0200, Tobias Klauser wrote: > > > On 2016-07-26 at 21:35:10 +0200, Vadim Kochan <vadi...@gmail.com> wrote: > > > > Extended 'struct packet_dyn' with proto fields which has > > > > dynamically changing values at runtime. > > > > > > > > Implement incrementing of proto field at runtime with min & max > > > > parameters, by default if the 'min' parameter is not specified > > > > then original value is used. For fields which len is greater > > > > than 4 - last 4 bytes are incremented as unsigned int value. > > > > > > > > Added 'field_changed' callback for proto header which > > > > may be used for check if csum updating is needed. This callback > > > > is called after field was changed at runtime. > > > > > > > > Added 'packet_update' callback to let proto header know > > > > when to apply final proto header changes at runtime (csum update). > > > > > > The documentation of these callbacks would also make sense where they're > > > defined. > > > > > > > Signed-off-by: Vadim Kochan <vadi...@gmail.com> > > > > --- > > > > trafgen.c | 9 ++++++ > > > > trafgen_conf.h | 7 ++++ > > > > trafgen_proto.c | 99 > > > > +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > > > > trafgen_proto.h | 26 +++++++++++++++ > > > > 4 files changed, 141 insertions(+) > > > > > > > > diff --git a/trafgen.c b/trafgen.c > > > > index b76b5d7..553dfa5 100644 > > > > --- a/trafgen.c > > > > +++ b/trafgen.c > > > > void proto_packet_finish(void) > > > > { > > > > struct proto_hdr **headers = ¤t_packet()->headers[0]; > > > > @@ -433,3 +446,89 @@ void proto_packet_finish(void) > > > > p->packet_finish(p); > > > > } > > > > } > > > > + > > > > +static inline unsigned int field_inc(struct proto_field *field) > > > > +{ > > > > + uint32_t val; > > > > + > > > > + val = field->func.val - field->func.min; > > > > + val = (val + field->func.inc) % field->func.max; > > > > > > Shouldn't this be > > > > > > val = (val + field->func.inc) % (field->func.max - field->func.min + 1) > > > > > > to be consistent with apply_counter()? > > I simplified it and now it really works well: > > #define max_int32(a, b) > \ > ({ > \ > int32_t _a = (int32_t) (a); > \ > int32_t _b = (int32_t) (b); > \ > _a - ((_a - _b) & ((_a - _b) >> (sizeof(int32_t) * 8 - > 1))); \
The line above definitely needs an explanatory comment. How and why does this work? Why is it implemented like this instead of the "obvious" max() solution? > }) > > static inline unsigned int field_inc(struct proto_field *field) > { > uint32_t min = field->func.min; > uint32_t max = field->func.max; > uint32_t val = field->func.val; > uint32_t inc = field->func.inc; > uint32_t next; > > next = (val + inc) % (max + 1); > field->func.val = max_int32(next, min); > > return val; > } > > so max_int32(a,b) should be fast enough w/o branching. Have you profiled this against other possible implementations, especially the max_int32() implementation above? If your profiling doesn't show significant improvements of this max_int32() variant I'd rather stay with the "obvious" one, i.e. a > b ? a : b > > Sure, I tried this approach while implementing 1st version but when I > > used the following case: > > > > trafgen/trafgen -o lo -n 10 --cpu 1 '{ eth(type=0x800), fill(0xff, 10), > > dinc(5, 20, 5) }' > > > > then interval between 5 & 20 changes very differently. But in my version > > it repeats from 5 till 20 (yes here is a little difference that initial > > value is incremented immideately). Also semantic of proto dinc is > > dinc(step, min, max), and I will change it to looks like low-level one - > > dinc(min, max, step). > > > > > > > > Also, I think you should probably get rid of as many pointer > > > dereferences as possible in these runtime functions, i.e. store max and > > > min in temporary variables. > > > > OK, makes sense. > > > > > > > > > + field->func.val = val + field->func.min; > > > > + > > > > + return field->func.val; > > > > +} > > > > + > > > > +static void field_inc_func(struct proto_field *field) > > > > +{ > > > > + if (field->len == 1) { > > > > + uint8_t val; > > > > + > > > > + val = field_inc(field); > > > > + proto_field_set_u8(field->hdr, field->id, val); > > > > > > Assignment on declaration please. Or even better: > > > > > > proto_field_set_u8(field->hdr, field->id, field_inc(field)); > > > > OK > > > > > > > > > + } else if (field->len == 2) { > > > > + uint16_t val; > > > > + > > > > + val = field_inc(field); > > > > + proto_field_set_be16(field->hdr, field->id, val); > > > > > > Same. > > OK > > > > > > > > > + } else if (field->len == 4) { > > > > + uint32_t val; > > > > + > > > > + val = field_inc(field); > > > > + proto_field_set_be32(field->hdr, field->id, val); > > > > > > Same. > > OK > > > > > > > > > + } else if (field->len > 4) { > > > > + uint8_t *bytes = __proto_field_get_bytes(field); > > > > + uint32_t val; > > > > + > > > > + bytes += field->len - 4; > > > > + val = field_inc(field); > > > > + > > > > + *(uint32_t *)bytes = bswap_32(val); > > > > > > This part looks really odd. Did you actually verify it produces the > > > correct result on both big/little endian and for various field lengths? > > > > > > To be honest I don't see much use for counters going beyond UINT32_T_MAX > > > (or maybe UINT64_T_MAX, which should be handled as a separate case if > > > then). Or do you know of a protocol with sequence numbers (or similar) > > > > 64 bit for which this would really be useful? > > > > > Hm, may be it looks & sounds odd but I use it for incrementing MAC & IPv6 > > addresses (the last 4 bytes, it might be improved to 8 bytes for x64 > > arch). In the future I think to extend syntax to allow specify interval > > of incrementing like: > > > > ipv4(saddr[0:3]=dinc()) > > > > or may be you have better idea, but I dont wanna extend dinc() for this. > > Also I think may be in case of MAC/IPv6 (field->len > 4) - use index of the > current > incremented byte and when it is reached 0xFF - pick the next one. But if > you OK with current approach (but I am not sure you do) - I will change it in > future patches. Ok, I see. Incrementing MAC/IP adresses would indeed be useful. -- You received this message because you are subscribed to the Google Groups "netsniff-ng" group. To unsubscribe from this group and stop receiving emails from it, send an email to netsniff-ng+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.