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Commit 1e11a971 authored by Grzegorz Daniluk's avatar Grzegorz Daniluk
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doc: move adding new OIDs to SNMP as appendix

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......@@ -937,135 +937,6 @@ To verify that database is empty:
SFP database empty
\end{lstlisting}
% --------------------------------------------------------------------------
\subsubsection{Adding new objects to the SNMP}
\label{Adding new objects to the SNMP}
The \textit{Mini SNMP responder} can be easily expanded to export new objects.
Values of new objects can come from WRPC's variables or other HDL modules
as long as there is a proper interface to the WRPC to read these values.
This section contains the instruction how to export new objects with
the given variables' content.
The \textit{Mini SNMP responder} internally divides all OIDs into two parts.
The first part is called \textit{limb}. The \textit{limb} part of the incoming OID is
matched by a function \texttt{snmp\_respond}, with the defined \textit{limb} parts of OIDs
in the structure \texttt{oid\_limb\_array}.
When the \textit{limb} part is matched then the corresponding function from
the structure \texttt{oid\_limb\_array} is called to try to match the second part of
OID (the \textit{twig} part).
\begin{sloppypar} % to prevent \texttt{} from going to the margine
The example below adds to the \textit{Mini SNMP responder} an \texttt{int32\_t} variable
(\texttt{example\_i32var}) with OID \texttt{1.3.6.1.4.1.96.102.1.1.0} and a string
(\texttt{example\_string}) with OID \texttt{1.3.6.1.4.1.96.102.1.2.0}.
Before assigning new OIDs in your projects please contact the maintainer of
\texttt{wrpc-sw} repo to avoid conflicts.
\end{sloppypar}
\begin{itemize*}
\item First declare \texttt{example\_i32var} and \texttt{example\_string}:
\begin{lstlisting}
static int32_t example_i32var;
static char example_string[] = "test string";
\end{lstlisting}
\item Define the \textit{limb} part of the OID:
\begin{lstlisting}
static uint8_t oid_wrpcExampleGroup[] = {0x2B,6,1,4,1,96,101,99};
\end{lstlisting}
\item Define the \textit{twig} part of the OID:
\begin{lstlisting}
static uint8_t oid_wrpcExampleV1[] = {1,0};
static uint8_t oid_wrpcExampleV2[] = {2,0};
\end{lstlisting}
\item Add a group definition to the \texttt{struct snmp\_oid\_limb oid\_limb\_array}.
Please note that this structure has to be sorted by ascending OIDs.
\begin{lstlisting}
OID_LIMB_FIELD(oid_wrpcExampleGroup, func_group, oid_array_wrpcExampleGroup),
\end{lstlisting}
The macro \texttt{OID\_LIMB\_FIELD} takes the following arguments:
\begin{itemize*}
\item \texttt{oid\_wrpcExampleGroup} -- an array with the \textit{limb} part of the
OID
\item \texttt{func\_group} -- a function to be called when the \textit{limb} part of
the OID is matched; this function will try to match the \textit{twig} part
of the OID within a table or a group.
\item \texttt{oid\_array\_wrpcExampleGroup} -- an array of \textit{twig} parts of OIDs
\end{itemize*}
\item Declare a previously used \texttt{oid\_wrpcExampleGroup}. Please note that
this structure has to be sorted by ascending \textit{twig} part of OIDs.
\begin{lstlisting}
static struct snmp_oid oid_array_wrpcExampleGroup[] = {
OID_FIELD_VAR(oid_wrpcExampleV1, get_p, set_p, ASN_INTEGER, &example_i32var),
OID_FIELD_VAR(oid_wrpcExampleV2, get_p, set_p, ASN_OCTET_STR, &example_string),
{ 0, }
};
\end{lstlisting}
The macro \texttt{OID\_FIELD\_VAR} takes the following arguments:
\begin{itemize*}
\item \texttt{oid\_wrpcExampleV1} -- an array with \textit{twig} part of the OID
\item \texttt{get\_p} (or \texttt{get\_pp)} -- a function to be called when \textit{twig}
part of the OID is matched for SNMP GET requests;
\item \texttt{set\_p} (or \texttt{set\_pp)} -- a function to be called when a \textit{twig}
part of the OID is matched for SNMP SET requests; if no SET
functionality is planned, please use NULL
\item \texttt{ASN\_INTEGER, ASN\_OCTET\_STR} -- type of the OID; please
check the source for other possible types
\item \texttt{\&example\_i32var, \&example\_string} -- addresses to the data in
memory
\end{itemize*}
In case the address of variable is not known at boot, it is possible to define
a pointer to the variable which will be initialized (e.g. in the \texttt{snmp\_init}
the function) at the boot time. In that case function \texttt{get\_pp} (\texttt{set\_pp}) has
to be used instead of \texttt{get\_p} (\texttt{set\_p}). For variables that are a part of
a structure and have to be accessed via a pointer, a macro \texttt{OID\_FIELD\_STRUCT}
is available.
For more complex extraction of variables or run-time value corrections,
it is possible to use a custom \textit{get} function. It is possible to pass
a constant number to the custom function instead of an address. For example:
\begin{lstlisting}
OID_FIELD_VAR(oid_wrpcPtpServoUpdateTime, get_servo, NO_SET, ASN_COUNTER64, \
SERVO_UPDATE_TIME),
\end{lstlisting}
\end{itemize*}
Perform a \texttt{snmpwalk} to get new OIDs:
\begin{lstlisting}
$ snmpwalk -On $SNMP_OPT 1.3.6.1.4.1.96.102.1
.1.3.6.1.4.1.96.102.1.1.0 = INTEGER: 123432
.1.3.6.1.4.1.96.102.1.2.0 = STRING: "test string"
End of MIB
\end{lstlisting}
Trying to set too long string into the \texttt{example\_string} results in an error:
\begin{lstlisting}
$ snmpset -On $SNMP_OPT 1.3.6.1.4.1.96.102.1.2.0 s "new long string"
Error in packet.
Reason: (badValue) The value given has the wrong type or length.
Failed object: .1.3.6.1.4.1.96.102.1.2.0
\end{lstlisting}
A short enough (not longer than defined \texttt{"test string"}) value succeeds:
\begin{lstlisting}
$ snmpset -On $SNMP_OPT 1.3.6.1.4.1.96.102.1.2.0 s "new value12"
.1.3.6.1.4.1.96.102.1.2.0 = STRING: "new value12"
\end{lstlisting}
Set 999 to the \texttt{example\_i32var}:
\begin{lstlisting}
$ snmpset -On $SNMP_OPT 1.3.6.1.4.1.96.102.1.1.0 i 999
.1.3.6.1.4.1.96.102.1.1.0 = INTEGER: 999
\end{lstlisting}
Perform \texttt{snmpwalk} to verify changes:
\begin{lstlisting}
$ snmpwalk -On $SNMP_OPT 1.3.6.1.4.1.96.102.1
.1.3.6.1.4.1.96.102.1.1.0 = INTEGER: 999
.1.3.6.1.4.1.96.102.1.2.0 = STRING: "new value12"
End of MIB
\end{lstlisting}
% --------------------------------------------------------------------------
\subsubsection{Mini SNMP responder's tests}
\label{Mini SNMP responder's tests}
......@@ -1796,12 +1667,134 @@ or
This is not needed if the dump is retrieved using Etherbone.
% ##########################################################################
% LocalWords: gnudd titlepage iftex texinfo CERN documentlanguage settitle
% LocalWords: documentencoding setfilename afourpaper paragraphindent FPGA
% LocalWords: setchapternewpage finalout gateware ohwr modprobe insmod cset
% LocalWords: smallexample ctrl timestamp fdelay struct spusa hdlmake Xilinx
% LocalWords: bitstream wrpc init EEPROM grandmaster wrpcsw noposix http
% LocalWords: tarball toolchain specsw sudo Etherbone
\newpage
\section{Adding new objects to the SNMP}
\label{Adding new objects to the SNMP}
The \textit{Mini SNMP responder} can be easily expanded to export new objects.
Values of new objects can come from WRPC's variables or other HDL modules
as long as there is a proper interface to the WRPC to read these values.
This section contains the instruction how to export new objects with
the given variables' content.
The \textit{Mini SNMP responder} internally divides all OIDs into two parts.
The first part is called \textit{limb}. The \textit{limb} part of the incoming OID is
matched by a function \texttt{snmp\_respond}, with the defined \textit{limb} parts of OIDs
in the structure \texttt{oid\_limb\_array}.
When the \textit{limb} part is matched then the corresponding function from
the structure \texttt{oid\_limb\_array} is called to try to match the second part of
OID (the \textit{twig} part).
\begin{sloppypar} % to prevent \texttt{} from going to the margine
The example below adds to the \textit{Mini SNMP responder} an \texttt{int32\_t} variable
(\texttt{example\_i32var}) with OID \texttt{1.3.6.1.4.1.96.102.1.1.0} and a string
(\texttt{example\_string}) with OID \texttt{1.3.6.1.4.1.96.102.1.2.0}.
Before assigning new OIDs in your projects please contact the maintainer of
\texttt{wrpc-sw} repo to avoid conflicts.
\end{sloppypar}
\begin{itemize*}
\item First declare \texttt{example\_i32var} and \texttt{example\_string}:
\begin{lstlisting}
static int32_t example_i32var;
static char example_string[] = "test string";
\end{lstlisting}
\item Define the \textit{limb} part of the OID:
\begin{lstlisting}
static uint8_t oid_wrpcExampleGroup[] = {0x2B,6,1,4,1,96,101,99};
\end{lstlisting}
\item Define the \textit{twig} part of the OID:
\begin{lstlisting}
static uint8_t oid_wrpcExampleV1[] = {1,0};
static uint8_t oid_wrpcExampleV2[] = {2,0};
\end{lstlisting}
\item Add a group definition to the \texttt{struct snmp\_oid\_limb oid\_limb\_array}.
Please note that this structure has to be sorted by ascending OIDs.
\begin{lstlisting}
OID_LIMB_FIELD(oid_wrpcExampleGroup, func_group, oid_array_wrpcExampleGroup),
\end{lstlisting}
The macro \texttt{OID\_LIMB\_FIELD} takes the following arguments:
\begin{itemize*}
\item \texttt{oid\_wrpcExampleGroup} -- an array with the \textit{limb} part of the
OID
\item \texttt{func\_group} -- a function to be called when the \textit{limb} part of
the OID is matched; this function will try to match the \textit{twig} part
of the OID within a table or a group.
\item \texttt{oid\_array\_wrpcExampleGroup} -- an array of \textit{twig} parts of OIDs
\end{itemize*}
\item Declare a previously used \texttt{oid\_wrpcExampleGroup}. Please note that
this structure has to be sorted by ascending \textit{twig} part of OIDs.
\begin{lstlisting}
static struct snmp_oid oid_array_wrpcExampleGroup[] = {
OID_FIELD_VAR(oid_wrpcExampleV1, get_p, set_p, ASN_INTEGER, &example_i32var),
OID_FIELD_VAR(oid_wrpcExampleV2, get_p, set_p, ASN_OCTET_STR, &example_string),
{ 0, }
};
\end{lstlisting}
The macro \texttt{OID\_FIELD\_VAR} takes the following arguments:
\begin{itemize*}
\item \texttt{oid\_wrpcExampleV1} -- an array with \textit{twig} part of the OID
\item \texttt{get\_p} (or \texttt{get\_pp)} -- a function to be called when \textit{twig}
part of the OID is matched for SNMP GET requests;
\item \texttt{set\_p} (or \texttt{set\_pp)} -- a function to be called when a \textit{twig}
part of the OID is matched for SNMP SET requests; if no SET
functionality is planned, please use NULL
\item \texttt{ASN\_INTEGER, ASN\_OCTET\_STR} -- type of the OID; please
check the source for other possible types
\item \texttt{\&example\_i32var, \&example\_string} -- addresses to the data in
memory
\end{itemize*}
In case the address of variable is not known at boot, it is possible to define
a pointer to the variable which will be initialized (e.g. in the \texttt{snmp\_init}
the function) at the boot time. In that case function \texttt{get\_pp} (\texttt{set\_pp}) has
to be used instead of \texttt{get\_p} (\texttt{set\_p}). For variables that are a part of
a structure and have to be accessed via a pointer, a macro \texttt{OID\_FIELD\_STRUCT}
is available.
For more complex extraction of variables or run-time value corrections,
it is possible to use a custom \textit{get} function. It is possible to pass
a constant number to the custom function instead of an address. For example:
\begin{lstlisting}
OID_FIELD_VAR(oid_wrpcPtpServoUpdateTime, get_servo, NO_SET, ASN_COUNTER64, \
SERVO_UPDATE_TIME),
\end{lstlisting}
\end{itemize*}
Perform a \texttt{snmpwalk} to get new OIDs:
\begin{lstlisting}
$ snmpwalk -On $SNMP_OPT 1.3.6.1.4.1.96.102.1
.1.3.6.1.4.1.96.102.1.1.0 = INTEGER: 123432
.1.3.6.1.4.1.96.102.1.2.0 = STRING: "test string"
End of MIB
\end{lstlisting}
Trying to set too long string into the \texttt{example\_string} results in an error:
\begin{lstlisting}
$ snmpset -On $SNMP_OPT 1.3.6.1.4.1.96.102.1.2.0 s "new long string"
Error in packet.
Reason: (badValue) The value given has the wrong type or length.
Failed object: .1.3.6.1.4.1.96.102.1.2.0
\end{lstlisting}
A short enough (not longer than defined \texttt{"test string"}) value succeeds:
\begin{lstlisting}
$ snmpset -On $SNMP_OPT 1.3.6.1.4.1.96.102.1.2.0 s "new value12"
.1.3.6.1.4.1.96.102.1.2.0 = STRING: "new value12"
\end{lstlisting}
Set 999 to the \texttt{example\_i32var}:
\begin{lstlisting}
$ snmpset -On $SNMP_OPT 1.3.6.1.4.1.96.102.1.1.0 i 999
.1.3.6.1.4.1.96.102.1.1.0 = INTEGER: 999
\end{lstlisting}
Perform \texttt{snmpwalk} to verify changes:
\begin{lstlisting}
$ snmpwalk -On $SNMP_OPT 1.3.6.1.4.1.96.102.1
.1.3.6.1.4.1.96.102.1.1.0 = INTEGER: 999
.1.3.6.1.4.1.96.102.1.2.0 = STRING: "new value12"
End of MIB
\end{lstlisting}
\end{document}
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