Fix: Document nasl functions

doc/manual/nasl/built-in-functions/host-functions/ip_reverse_lookup.md

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+# ip_reverse_lookup
+
+## NAME
+
+**ip_reverse_lookup** - gets the host name of the either the given IP address or the current target
+
+## SYNOPSIS
+
+*string* **ip_reverse_lookup**( *string* );
+
+Takes an optional *string* parameter, which is the IP address to look up. If no parameter is given, the IP address of the current target is used.
+
+## DESCRIPTION
+
+This function uses the `gethostbyaddr` function to get the host name of the given IP address. If no IP address is given, the IP address of the current target is used.
+
+## RETURN VALUE
+
+Return the found host name or NULL if the host name could not be retrieved. 

doc/manual/nasl/built-in-functions/krb5/krb5_error_code_to_string.md

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+# krb5_error_code_to_string
+
+## NAME
+
+**krb5_error_code_to_string** - Returns a string representation of either the given code or the cached code.
+
+## SYNOPSIS
+
+*str* **krb5_error_code_to_string**(int);
+
+
+## DESCRIPTION
+
+Returns a string representation of either the given code or the cached code.
+
+The cached code reflects the error code of the last krb5 function call.
+
+
+## RETURN VALUE
+
+Returns a human readable version of the result code.
+
+## EXAMPLES
+
+```nasl
+login       = string( get_kb_item( "KRB5/login_filled/0" ) );
+password    = string( get_kb_item( "KRB5/password_filled/0" ) );
+realm = string( get_kb_item( "KRB5/realm_filled/0" ) );
+kdc         = string( get_kb_item( "KRB5/kdc_filled/0" ) );
+host        = ip_reverse_lookup(); # must be a domain name.
+
+result = krb5_gss_prepare_context(realm: realm, kdc: kdc, host: host, service: 'cifs', user: login, password: passwod);
+if (krb5_is_failure(result)) {
+        display(krb5_error_code_to_string(result));
+}
+display(krb5_error_code_to_string());
+```
+

doc/manual/nasl/built-in-functions/krb5/krb5_find_kdc.md

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+# krb5_find_kdc
+
+## NAME
+
+**krb5_find_kdc** - Find the KDC for a given realm 
+
+## SYNOPSIS
+
+*string* **krb5_find_kdc**(realm: *string*);
+
+**insstr** takes named argument `realm`.
+
+## DESCRIPTION
+
+This function opens the krb5.conf file (located either by environment variable KRB5_CONFIG or /etc/ktrb5.conf) and looks for an kdc entry for the given realm.
+
+
+## RETURN VALUE
+
+The found KDC or *NULL* if the KDC could not be found.
+
+## ERRORS
+
+Returns *NULL* if the realm is not found or the krb5.conf file could not be opened.
+
+## EXAMPLES
+
+```c#
+kdc = insstr(realm: 'EXAMPLE.COM');
+display(kdc);
+```
+
+

doc/manual/nasl/built-in-functions/krb5/krb5_gss_init.md

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+# krb5_gss_init
+
+## NAME
+
+**krb5_gss_init** - initialize the krb5 GSS-API library
+
+## SYNOPSIS
+
+*int* **krb5_gss_init**();
+
+**krb5_gss_init** takes no arguments.
+
+## DESCRIPTION
+
+Initializes the krb5 GSS-API library. This function can be ommited when gss_prepare_context is called.
+
+When there is an already initialized context it will be destroyed and a new one will be created.
+
+## RETURN VALUE
+
+Returns 0 on success otherwise it is an failure.
+
+
+## EXAMPLES
+
+```c#
+result = krb5_gss_init();
+if (krb5_is_failure(result)) {
+	exit(42);
+}
+```
+
+

doc/manual/nasl/built-in-functions/krb5/krb5_gss_prepare_context.md

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+# krb5_gss_prepare_context
+
+## NAME
+
+**krb5_gss_prepare_context** - Creates tne initial ticket request for the krb5 GSS-API library and prepares the context for further use.
+
+## SYNOPSIS
+
+*int* **krb5_gss_prepare_context**(config_patn: str, realm: str, kdc: str, host: str, service: str, user: str, password: str);
+
+The config_path argument is optional and can be omitted. When it is not set it tries to read it from the `KRB5_CONFIG` environment variables and falls back to `/etc/krb5.conf`. The other arguments are required.
+
+- realm - The realm of the domain.
+- kdc - The KDC server to use. Can be a comma separated list of servers. The first server in the list is the primary server.
+- host - The host to use for the ticket request. Usually the host where the service is running.
+- service - The service to request the ticket for.
+- user - The user to request the ticket for.
+- password - The password of the user.
+
+## DESCRIPTION
+
+When krb5_gss_prepare_context is called it creates the initial ticket request for the krb5 GSS-API library and prepares the context for further use.
+
+It can be used directly without calling krb5_gss_init first.
+
+
+## RETURN VALUE
+
+Returns 0 on success otherwise it is an failure.
+
+
+## EXAMPLES
+
+```c#
+login       = string( get_kb_item( "KRB5/login_filled/0" ) );
+password    = string( get_kb_item( "KRB5/password_filled/0" ) );
+realm = string( get_kb_item( "KRB5/realm_filled/0" ) );
+kdc         = string( get_kb_item( "KRB5/kdc_filled/0" ) );
+host        = ip_reverse_lookup(); # must be a domain name.
+
+result = krb5_gss_prepare_context(realm: realm, kdc: kdc, host: host, service: 'cifs', user: login, password: passwod);
+if (krb5_is_failure(result)) {
+	exit(42);
+}
+```
+

doc/manual/nasl/built-in-functions/krb5/krb5_gss_session_key.md

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+# krb5_gss_session_key
+
+## NAME
+
+**krb5_gss_session_key** - Returns the session key or NULL if none was found.
+
+## SYNOPSIS
+
+*str* **krb5_gss_update_context_session_key**();
+
+
+## DESCRIPTION
+
+Returns the session key found within the context when the last `krb5_gss_update_context` was called. If no session key was found, NULL is returned.
+
+
+## RETURN VALUE
+
+Returns the session key or NULL if none was found.
+
+## EXAMPLES
+
+```nasl
+login       = string( get_kb_item( "KRB5/login_filled/0" ) );
+password    = string( get_kb_item( "KRB5/password_filled/0" ) );
+realm = string( get_kb_item( "KRB5/realm_filled/0" ) );
+kdc         = string( get_kb_item( "KRB5/kdc_filled/0" ) );
+host        = ip_reverse_lookup(); # must be a domain name.
+
+result = krb5_gss_prepare_context(realm: realm, kdc: kdc, host: host, service: 'cifs', user: login, password: passwod);
+if (krb5_is_failure(result)) {
+	exit(42);
+}
+if (krb5_is_failure(krb5_gss_update_context())) {
+	exit(42);
+}
+if (krb5_update_context_needs_more()) {
+   session_key = krb5_gss_session_key();
+}
+```
+

doc/manual/nasl/built-in-functions/krb5/krb5_gss_update_context.md

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+# krb5_gss_update_context
+
+## NAME
+
+**krb5_gss_update_context** - Updates the context with the provided data and caches the output for the application.
+
+## SYNOPSIS
+
+*int* **krb5_gss_update_context**(str);
+
+Has an optional positional argument that contains the byte arrary to send to the KDC.
+
+## DESCRIPTION
+
+Initializes the security context with the provided data and caches the output for the application.
+
+When the service is `cifs` the first call of `krb5_gss_update_context` must be without data.
+
+As this method returns an error code the caller must get the data for the application via `krb5_gss_update_context_out()`.
+
+To verify if the process requires further step the caller must call `krb5_gss_update_context_needs_more()`.
+
+
+## RETURN VALUE
+
+Returns 0 on success otherwise it is an failure.
+
+
+## EXAMPLES
+
+```nasl
+login       = string( get_kb_item( "KRB5/login_filled/0" ) );
+password    = string( get_kb_item( "KRB5/password_filled/0" ) );
+realm = string( get_kb_item( "KRB5/realm_filled/0" ) );
+kdc         = string( get_kb_item( "KRB5/kdc_filled/0" ) );
+host        = ip_reverse_lookup(); # must be a domain name.
+
+result = krb5_gss_prepare_context(realm: realm, kdc: kdc, host: host, service: 'cifs', user: login, password: passwod);
+if (krb5_is_failure(result)) {
+	exit(42);
+}
+result = krb5_gss_update_context();
+if (krb5_is_failure(result)) {
+	exit(42);
+}
+while (krb5_gss_update_context_needs_more()) {
+	out = krb5_gss_update_context_out();
+	soc = open_sock_tcp( 445 );
+	if( ! soc ) {
+	   exit(42);
+	}
+	send(socket:soc, data:out);
+	rec = recv(socket: sock);
+	if (!rec) {
+		exit(42);
+	} 
+	result = krb5_gss_update_context(rec);
+	if (krb5_is_failure(result)) {
+		exit(42);
+	}
+}
+```
+

doc/manual/nasl/built-in-functions/krb5/krb5_gss_update_context_needs_more.md

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+# krb5_gss_update_context_needs_more
+
+## NAME
+
+**krb5_gss_update_context_needs_more** - Returns true when the previous `krb5_gss_update_context` requires further information/calls.
+
+## SYNOPSIS
+
+*int* **krb5_gss_update_context_needs_more**();
+
+Returns 1 if the previous `krb5_gss_update_context` requires further information/calls, 0 otherwise.
+
+## DESCRIPTION
+
+This method is used to verify if the previous `krb5_gss_update_context` requires further information/calls.
+
+## RETURN VALUE
+
+
+Returns 1 if the previous `krb5_gss_update_context` requires further information/calls, 0 otherwise.
+
+## EXAMPLES
+
+```nasl
+login       = string( get_kb_item( "KRB5/login_filled/0" ) );
+password    = string( get_kb_item( "KRB5/password_filled/0" ) );
+realm = string( get_kb_item( "KRB5/realm_filled/0" ) );
+kdc         = string( get_kb_item( "KRB5/kdc_filled/0" ) );
+host        = ip_reverse_lookup(); # must be a domain name.
+
+result = krb5_gss_prepare_context(realm: realm, kdc: kdc, host: host, service: 'cifs', user: login, password: passwod);
+if (krb5_is_failure(result)) {
+	exit(42);
+}
+result = krb5_gss_update_context();
+if (krb5_is_failure(result)) {
+	exit(42);
+}
+if (krb5_gss_update_context_needs_more()) {
+	exit(0);	
+}
+```
+

doc/manual/nasl/built-in-functions/krb5/krb5_gss_update_context_out.md

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+# krb5_gss_update_context_out
+
+## NAME
+
+**krb5_gss_update_context_out** - Returns the data for the application to send to the service.
+
+## SYNOPSIS
+
+*str* **krb5_gss_update_context_out**();
+
+
+## DESCRIPTION
+
+This function is used to get the data that the application should send to the service.
+
+It should be called after `krb5_gss_update_context` to may get data that should be sent to the service. 
+
+The caller must check if the result is not NULL before using it.
+
+## RETURN VALUE
+
+Returns the data that should be sent to the service or NULL if there is no data to send.
+
+## EXAMPLES
+
+```nasl
+login       = string( get_kb_item( "KRB5/login_filled/0" ) );
+password    = string( get_kb_item( "KRB5/password_filled/0" ) );
+realm = string( get_kb_item( "KRB5/realm_filled/0" ) );
+kdc         = string( get_kb_item( "KRB5/kdc_filled/0" ) );
+host        = ip_reverse_lookup(); # must be a domain name.
+
+result = krb5_gss_prepare_context(realm: realm, kdc: kdc, host: host, service: 'cifs', user: login, password: passwod);
+if (krb5_is_failure(result)) {
+	exit(42);
+}
+result = krb5_gss_update_context();
+if ((out = krb5_gss_update_context_out())) {
+	soc = open_sock_tcp( 445 );
+	if( ! soc ) {
+	   exit(42);
+	}
+	send(socket:soc, data:out);
+}
+```
+