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[Harpreet Singh <harpreeta@xxxxxxxxxxxxx>]

Hi Didier,

Thanks for the response.

You are right.I was able to solve the problem.
by doing two things.

First in d_generic.c packet was being accessed using (uint16*) typecast.

The crash was happening here. I changed two byte access.

another issue i faced after this was feedback, in bidirectional
decompressor case.

i stopped that by allocating decompressor with NULL.

My system is point to point . What are the advantages of bidirectional
decompressor?

Thanks again,
Harpreet

On Tue, 2009-11-24 at 11:45 +0100, Didier Barvaux wrote:
> Hi,
> 
> > I am trying to used the rohc source code in my application for
> > uclinux.
> > 
> > I have done initialization of comp and decomp and crc tables as
> > described in the instructions.
> > 
> > I give 84 byte ip packet to rohc_compress function.
> > this works fine and does not crash and does shows rohc_size less than
> > 84.
> > 
> > for testing purpose i called rohc_decompress function immediately
> > after the rohc compress but decompress function crashes the
> > application when it tries to read the IP-ID from the ROHC_packet
> > given as input.
> >
> > [...]
> 
> I tested the code you put in your email on my Linux system without any
> problem. No crash at all. Your problem may come from :
>  - a problem of the ROHC library that appends only on uclinux,
>  - a difference between your program and mine for compressor and
>    decompressor initialisation.
> 
> In order to analyse the problem further, could you please run the test
> program I attached to my email and send me the output ?
> 
> You may compile it and run it as follow:
>  $ gcc -g -Wall -Werror -c -o test.o test.c
>  $ gcc -lrohc_common -lrohc_comp -lrohc_decomp -lm  test.o -o test
>  $ ./test
> [rohc_comp.c:67 rohc_alloc_compressor()] creating compressor
> 0x45 0x00 0x00 0x54 0x00 0x00 0x40 0x00 
> 0x40 0x01 0x85 0x42 0xc6 0xa8 0x14 0x0a 
> 0xc6 0xa8 0x14 0x0c 0x08 0x00 0x12 0xa4 
> 0xeb 0x02 0x00 0x00 0x40 0x7a 0xb9 0xde 
> 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 
> 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 
> 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 
> 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 
> 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 
> 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 
> 0x00 0x00 0x00 0x00 
> [rohc_comp.c:175 rohc_compress()] size of IP packet = 84 bytes
> [rohc_comp.c:198 rohc_compress()] IP protocol = 1
> [rohc_comp.c:203 rohc_compress()] no profile found, using default IP
> profile
> [rohc_comp.c:1121 c_find_context()] no context was found
> [rohc_comp.c:1035 c_create_context()] take the first unused context
> (CID = 0)
> [rohc_comp.c:1075 c_create_context()] context (CID = 0) created
> (num_used = 1)
> [rohc_comp.c:269 rohc_compress()] selected compression profile = IP /
> Compressor (0x0004)
> [rohc_comp.c:1302 c_piggyback_get()] add 0 byte(s) of feedback data
> [rohc_comp.c:287 rohc_compress()] compress the packet #1
> [c_generic.c:844 c_generic_encode()] SN = 1
> [c_generic.c:6120 changed_dynamic_both_hdr()] check for changed fields
> in the outer IP header
> [c_generic.c:862 c_generic_encode()] send_static = 0, send_dynamic = 0
> [c_generic.c:870 c_generic_encode()] ip_id = 0x0000, context_sn = 1
> [c_generic.c:2230 update_variables()] ip_id delta = 0xffffffff /
> 4294967295
> [c_generic.c:2231 update_variables()] ip_id bits = -1
> [c_generic.c:2241 update_variables()] sn bits=-1
> [c_generic.c:2579 decide_packet()] IR state
> [c_generic.c:2804 code_IR_packet()] code IR packet (CID = 0)
> [cid.c:57 code_cid_values()] CID = 0 => no add-CID
> [c_generic.c:2821 code_IR_packet()] type of packet + D flag = 0xfd
> [c_generic.c:2825 code_IR_packet()] profile ID = 0x04
> [c_generic.c:2831 code_IR_packet()] CRC = 0x00 for CRC calculation
> [c_generic.c:3096 code_ipv4_static_part()] version = 0x40
> [c_generic.c:3101 code_ipv4_static_part()] protocol = 0x01
> [c_generic.c:3111 code_ipv4_static_part()] src addr = c6 a8 14 0a
> [c_generic.c:3119 code_ipv4_static_part()] dst addr = c6 a8 14 0c
> [c_generic.c:3305 code_ipv4_dynamic_part()] TOS = 0x00, TTL = 0x40,
> IP-ID = 0x0000, df_rnd_nbo = 0xa0 (DF = 1, RND = 0, NBO = 1)
> [c_generic.c:2890 code_IR_packet()] SN = 1 -> 0x0001
> [c_generic.c:2896 code_IR_packet()] CRC (header length = 20, crc = 0xaa)
> [rohc_comp.c:362 rohc_compress()] ROHC size = 84 (feedback = 0, header
> = 20, payload = 64), output buffer size = 1024
> ip_size = 84 & rohc_size = 84
> 0xfd 0x04 0xaa 0x40 0x01 0xc6 0xa8 0x14
> 0x0a 0xc6 0xa8 0x14 0x0c 0x00 0x40 0x00
> 0x00 0xa0 0x00 0x01 0x08 0x00 0x12 0xa4
> 0xeb 0x02 0x00 0x00 0x40 0x7a 0xb9 0xde
> 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
> 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
> 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
> 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
> 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
> 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
> 0x00 0x00 0x00 0x00
> [rohc_decomp.c:399 rohc_decompress()] decompress the packet #1
> [rohc_decomp.c:550 d_decode_feedback_first()] skip 0 byte(s) of padding
> [rohc_decomp.c:846 rohc_ir_packet_crc_ok()] size of IR packet header :
> 20
> [rohc_decomp.c:865 rohc_ir_packet_crc_ok()] CRC OK (crc = 0xaa,
> profile_id = 4, largecid = 0, addcidUsed = 0, ir_size = 20)
> [d_generic.c:1465 d_generic_decode_ir()] decode an IR packet
> [d_generic.c:1769 d_decode_static_ip4()] IP Version = 4
> [d_generic.c:1775 d_decode_static_ip4()] Protocol = 0x01
> [d_generic.c:1781 d_decode_static_ip4()] Source Address = 0x0a14a8c6
> [d_generic.c:1787 d_decode_static_ip4()] Destination Address =
> 0x0c14a8c6
> [d_generic.c:1927 d_decode_dynamic_ip4()] TOS = 0x00
> [d_generic.c:1933 d_decode_dynamic_ip4()] TTL = 0x40
> [d_generic.c:1939 d_decode_dynamic_ip4()] IP-ID = 0x0000
> [d_generic.c:1952 d_decode_dynamic_ip4()] DF = 1, RND = 0, NBO = 1
> [d_generic.c:5316 build_uncompressed_ip4()] IP-ID = 0x0000
> [d_generic.c:5320 build_uncompressed_ip4()] IHL = 0x5
> [d_generic.c:5325 build_uncompressed_ip4()] Total Length = 0x0054 (IHL
> * 4 + 64)
> [d_generic.c:5328 build_uncompressed_ip4()] IP checksum = 0x8542
> [d_generic.c:5683 update_inter_packet()] current time = 1699587878 and
> last time = 0
> [d_generic.c:5697 update_inter_packet()] inter_arrival_time = 0 and
> current arrival delta is = 0
> [d_generic.c:1666 d_generic_decode_ir()] ROHC payload (length = 64
> bytes) starts at offset 20
> [rohc_decomp.c:411 rohc_decompress()] state in decompressor = 3
> [rohc_decomp.c:484 rohc_decompress()] feedback curr -12
> [rohc_decomp.c:491 rohc_decompress()] feedback curr 0
> [rohc_comp.c:124 rohc_free_compressor()] free contexts
> [rohc_comp.c:128 rohc_free_compressor()] free feedback buffer
> $ echo $?
> 0
> 
> Regards,
> 
> Didier Barvaux
> Viveris Technologies
> 
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