Fri Oct  6 23:15:32 CEST 2023
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The program decode-data.c has been added to the 'util' directory for decoding
data obtained from HAProxy via SPOP.  Can be used in such a way that hexa data
is copied from the log file created by the spoa-mirror program and used as the
only argument when calling the decode-data program.

Log file example:
..
[ 1][    2.985255]     frame_recv(0x7fae9c00b420) {
[ 1][    2.985256]       <1:49> --> Receiving data
[ 1][    2.985257]       tcp_recv(0x7fae9c00b420, 4, " length") {
[ 1][    2.985263]         <1:49> 4/4/4 byte(s) received frame length
[ 1][    2.985264]       } = 4
[ 1][    2.985267]       tcp_recv(0x7fae9c00b420, 129, " data") {
[ 1][    2.985269]         <1:49> 129/129/129 byte(s) received frame data
[ 1][    2.985270]       } = 129
[ 1][    2.985273]       <1:49> New frame of 129 bytes received: <0100000001000012737570706f727465642d76657273696f6e730803322e300e6d61782d6672616d652d73697a6503fcf0060c6361706162696c69746965730810706970656c696e696e672c6173796e6309656e67696e652d6964082463663730346564382d643962312d343533312d393537302d343162396366306166356533> <........supported-versions..2.0.max-frame-size.....capabilities..pipelining,async.engine-id.$cf704ed8-d9b1-4531-9570-41b9cf0af5e3>
[ 1][    2.985274]     } = 129
..

% ./decode-data -s 0100000001000012737570706f727465642d76657273696f6e730803322e300e6d61782d6672616d652d73697a6503fcf0060c6361706162696c69746965730810706970656c696e696e672c6173796e6309656e67696e652d6964082463663730346564382d643962312d343533312d393537302d343162396366306166356533
0x0000: 0x01 1
0x0001: 0x00 0
0x0002: 0x00 0
0x0003: 0x00 0
0x0004: 0x01 1
0x0005: 0x00 0
0x0006: 0x00 0
0x0007: 0x12 18
0x0008: supported-versions
0x001a: 0x08 8
0x001b: 0x03 3
0x001c: 2.0
0x001f: 0x0e 14
0x0020: max-frame-size
0x002e: 0x03 3
0x002f: 0xfc 252
0x0030: 0xf0 240
0x0031: 0x06 6
0x0032: 0x0c 12
0x0033: capabilities
0x003f: 0x08 8
0x0040: 0x10 16
0x0041: pipelining,async
0x0051: 0x09 9
0x0052: engine-id
0x005b: 0x08 8
0x005c: $cf704ed8-d9b1-4531-9570-41b9cf0af5e3

NOTE: in this case the program does not use a real frame data decoder, but only
distinguishes print characters (isprint()) which it displays as a string, while
everything else is displayed as a one-byte value.


Sun Oct  8 21:18:01 CEST 2023
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If we want to show the data as part of the frame, then the option '-f' is used
(only a part of the input data is shown here for the sake of clarity):

./decode-data -f 01000000..
01000000..
--> HAPROXY-HELLO decoding frame
--> HAPROXY-HELLO header 1 0x01000000 0 0
--> HAPROXY-HELLO stream-id=0 - frame-id=0
K/V item: key=supported-versions value='2.0' STR
K/V item: key=max-frame-size value=16380 VARINT
K/V item: key=capabilities value='pipelining,async' STR
K/V item: key=engine-id value='cf704ed8-d9b1-4531-9570-41b9cf0af5e3' STR
The frame is completely decoded.

NOTE: in order to get such a complete frame data debug output, it is necessary
to use --enable-debug when configuring the spoa-mirror program.  Otherwise,
part of the information will not be displayed when decoding the frame data;
as in the example below:

./decode-data -f 01000000..
01000000..
 value='2.0' STR
 value=16380 VARINT
 value='pipelining,async' STR
 value='cf704ed8-d9b1-4531-9570-41b9cf0af5e3' STR
The frame is completely decoded.