I have been checking for some static analysis tool in wikipedia.
I am checking each tool for its capability.
*-Automatic variable checking
-Bounds checking for array overruns
-Classes checking
etc.*
I am really not sure what capability is below:
Be able to check that the variable used in conditional statement is correctly assigned so that it either enters or ignore the statement.
Example1:
bool flag = false;
if( flag == true){
process1();
}
The tool should point out that line 2 is incorrect because it will always be false.
Example2:
bool flag = false;
flag = updateFlag();
if( flag == true){
process1();
}
The tool should not point out anything since the variable may change before it will be used as condition.
You can use the klockwork tool, which will tell you that code is not reachable i.e dead code.
see the fallowing checkers you can enable in klockwork.
https://docs.roguewave.com/en/klocwork/2016/candccheckerreference
Related
The code in question is similar to this SO topic: Get X11 window caption height. The link points to answer with Xlib code. The idea is to get window properties, _NET_FRAME_EXTENTS namely. The code waits untill the window manager will set the decoration sizes. The code in the answer skips all events till the property returned.
Basically I do the same with XCB. I want to know the decoration sizes of a window that I had just created. The pseudocode what I do with XCB:
cookie = xcb_get_property(...)
reply = xcb_get_property_reply(..., cookie, ...)
if(NULL == reply){
/* fail */
}
if(reply->type != type){
/* fail */
}
prop_size = xcb_get_property_value_length(reply);
prop_val = xcb_get_property_value (reply);
if(0 == prop_size){
/* fail */
}
if(/* not failed */){
copy returned data here
print and return success.
}
if(/* failed */)
then wait for events and skip them
repeat the above untill success
The problem is that sometimes values being returned as zeros, and sometimes the values are correct. As you can see from above code, the success condition is only when the type match and there is some data that are read. The request is checked with cookie so, as I understand, the reply belongs to the request. I do map the window and flush events before I call the above code.
The question is, how to get WM decorations properly with XCB?
I got tied to the linked SO topic. The answer in the topic do the right thing and gives a great insight but fails to execute it properly.
The solution is to wait for XCB_PROPERTY_NOTIFY event and compare the recieved atom with a _NET_FRAME_EXTENTS atom. If all checks went good, then WM has set the _NET_FRAME_EXTENTS property. Not earlier than that specific event is recieved, there is a sense to get values of the property. That is why I got zeroes in some invocations of the application. My original solution may get the property value earlier before WM sets the property.
Some pseudocode:
loop:
ev = xcb_wait_for_event(...);
...error checks...
if((ev->response_type & ~0x80) == XCB_PROPERTY_NOTIFY){
xcb_property_notify_event_t *pe = (xcb_property_notify_event_t*)ev;
if(pe->atom == {_NET_FRAME_EXTENTS atom}){
...get the _NET_FRAME_EXTENTS property...
}
}
...
loop end;
Is there any way, using static analysis tools(I'm using Codesonar now), to detect unreleased lock problems (something like unreleased semaphores) in the following program?（The comment part marked by arrows）
The project is a multi-task system using Round-robin scheduling, where new_request() is an interrupt task comes randomly and send_buffer() is another period task.
In real case, get_buffer() and send_buffer() are various types of wrappers, which contains many call layers until actual lock/unlock process. So I can't simply specify get_buffer() as lock function in settings of static analysis tool.
int bufferSize = 0; // say max size is 5
// random task
void new_request()
{
int bufferNo = get_buffer(); // wrapper
if (bufferNo == -1)
{
return; // buffer is full
}
if (check_something() == OK)
{
add_to_sendlist(bufferNo); // for asynchronous process of send_buffer()
}
else // bad request
{
// ↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓↓
// There should be clear_buffer placed here
// but forgotten. Eventually the buffer will be
// full and won't be cleared since 5th bad request comes.
// ↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑
do_nothing();
// clear_buffer(bufferNo);
}
}
int get_buffer()
{
if(bufferSize < 5)
{
bufferSize++;
return bufferSize;
}
else
{
wait_until_empty(); // wait until someone is sent by send_buffer()
return -1;
}
}
// clear specifiled one in buffer
void clear_buffer(int bufferNo)
{
delete(bufferNo)
bufferSize--;
}
// period task
void send_buffer()
{
int sent = send_1st_stuff_in_list();
clear_buffer(sent);
}
yoyozi - Fair disclosure: I'm an engineer at GrammaTech who works on CodeSonar.
First some general things. The relevant parts of the manual for this are on the page: codesonar/doc/html/C_Module/LibraryModels/ConcurrencyModelsLocks.html. Especially the bottom of the page on Resolving Lock Operation Identification Problems.
Based on your comments, I think you have already read this, since you address setting the names in the configuration settings.
So then the question is how many different wrappers do you have? If it is only a few, then the settings in the configuration file are the way to go. If there are many, that gets tedious. And if there are very many it becomes practically impossible.
So knowing some estimate for how many wrapper sets you have would help.
Even with the wrappers accounted for, it may be that the deadlock and race detectors aren't quite what you need for your problem.
If I understand your issue correctly, you have a queue with limited space, and by accident malformed items don't get cleaned out of the queue, and so the queue gets full and that stalls all processing. While you may have multiple threads involved in this implementation, the issue itself would still be a problem in a basically serial setting.
The best way to work with an issue like this is to try and make a simpler example that displays the same core problem. If you can do this in a way that can be shared with GrammaTech, we can work with you on ways to adjust settings or maybe provide hints to the analysis so it can find this issue.
If you would like to talk about this in more detail, and with prodetction against public disclosure of your code, please contact us at support_at_grammatech_dot_com, where the at and dot should be replaced as needed to make a well formed email address.
I have an issue of an if statement not passing whilst my system gatt connection is not made.
Context
I have a BLE system using a NRF52840-dk board programmed in C. I also have a mobile application which, communicates with this board via a Gatt connection. I have a single service with a single characteristic. I write to this characteristic from my mobile application and, from this do some processing. At the moment I can send over a timestamp and begin storing data. However, I need to then send data back to my mobile device by this connection.
So what I have is a command to be sent from the phone to ask for some data. This should then send data back to the phone by changing the characteristic value.
Before I can change the value I need to see if the command has been issued. However, due to the priorities and constraints of the device I need to do this processing in the main function not in the BLE interrupt that I have done my time stamping in. This is due to the data I will be transmitting eventually will be large.
My issue however is, I receive the command to send some data back to the phone and update a global int value (changed from 0 to 1). Then in my main loop test this value and, if it is 1 write to the terminal and change the value back. I would then use this point of the code to run a function to send the data.
But this statement does not pass.
This is my main loop code
if(GATT_CONNECTED == false)//This works!
{
//Do some functions here
}
else if (GATT_CONNECTED == true)// GATT_CONNECTED = true
{
NRF_LOG_INFO("Test1 passed");//Testing variable this does not print
if(main_test == 1)
{
NRF_LOG_INFO("Test2 passed");//This does not print either irrelevant of value
main_test = 0;//False
}
idle_state_handle();
}
I don't know if the issue is the way I have defined my variable or due to interrupt priorities or something like that. But, when my Gatt connection is made the loop of (GATT_CONNECTED == true) does not seem to process.
My variable is defined in another file where my GATT connection is handled. The GATT connected variable is handled in main. my main_test variable is defined in another c file as int main_test = 0;. In the header declared as extern int main_test;.
I know the GATT_CONNECTED variable works as I have code in it that only runs when my gatt is not connected. I have omitted it for simplicity.
Any ideas,
Thanks
Ps Hope you are all keeping well and, safe
Edit
Added code for simplicity
main.c
bool GATT_CONNECTED = false;
int main(void)
{
Init_Routine();
while(1)
{
Process_data();//This runs if the gatt is not connected if statement inside
if(GATT_CONNECTED == true)//This does not run true when the gatt is connected
{
NRF_LOG_INFO("check gatt connectedpassed");//Testing variable.
nrf_gpio_pin_set(LED_4);//Turn an LED on once led 4 does not work
}
idle_state_handle();
}
}
I'm using CryptEncryptMessage to generate a PKCS#7 enveloped message. I'm using szOID_NIST_AES256_CBC as the encryption algorithm.
The generated message appears to be valid but is the RSAES-OAEP for the Key Transport Algorithm which has limited support in the wild (Thunderbird, OpenSSL SMIME Module among many others don't support it).
I'll like for CAPI to revert to the older RSAencryption for key transport.
Is there any possible way to do that, I could revert to the low level messaging functions if there is a way rather than to use CryptEncryptMessage but I can't find a way to do that even using the low level functions.
Code:
CRYPT_ENCRYPT_MESSAGE_PARA EncryptMessageParams;
EncryptMessageParams.cbSize = sizeof(CMSG_ENVELOPED_ENCODE_INFO);
EncryptMessageParams.dwMsgEncodingType = PKCS_7_ASN_ENCODING;
EncryptMessageParams.ContentEncryptionAlgorithm.pszObjId = szOID_NIST_AES256_CBC;
EncryptMessageParams.ContentEncryptionAlgorithm.Parameters.cbData = 0;
EncryptMessageParams.ContentEncryptionAlgorithm.Parameters.pbData = 0;
EncryptMessageParams.hCryptProv = NULL;
EncryptMessageParams.pvEncryptionAuxInfo = NULL;
EncryptMessageParams.dwFlags = 0;
EncryptMessageParams.dwInnerContentType = 0;
BYTE pbEncryptedBlob[640000];
DWORD pcbEncryptedBlob = 640000;
BOOL retval = CryptEncryptMessage(&EncryptMessageParams, cRecipientCert, pRecipCertContextArray, pbMsgText, dwMsgTextSize, pbEncryptedBlob, &pcbEncryptedBlob);
The Key Transport Algorithm is a bit tricky to handle, and it may not serve its purpose (I see you noted that you'd like CAPI to support RSAencryption; trust me, I would too). It looks like you've alaready detected the bulk of your problem - The generated message appears is valid, but your method makes it necessary to use CryptEncryptMessage, which won't work well/at all in the long run.
Step 1 - Examine the Code
CRYPT_ENCRYPT_MESSAGE_PARA EncryptMessageParams;
EncryptMessageParams.cbSize = sizeof(CMSG_ENVELOPED_ENCODE_INFO);
EncryptMessageParams.dwMsgEncodingType = PKCS_7_ASN_ENCODING;
EncryptMessageParams.ContentEncryptionAlgorithm.pszObjId = szOID_NIST_AES256_CBC;
EncryptMessageParams.ContentEncryptionAlgorithm.Parameters.cbData = 0;
EncryptMessageParams.ContentEncryptionAlgorithm.Parameters.pbData = 0;
EncryptMessageParams.hCryptProv = NULL;
EncryptMessageParams.pvEncryptionAuxInfo = NULL;
EncryptMessageParams.dwFlags = 0;
EncryptMessageParams.dwInnerContentType = 0;
BYTE pbEncryptedBlob[640000];
DWORD pcbEncryptedBlob = 640000;
BOOL retval = CryptEncryptMessage(&EncryptMessageParams, cRecipientCert, pRecipCertContextArray, pbMsgText, dwMsgTextSize, pbEncryptedBlob, &pcbEncryptedBlob);
Pretty basic, isn't it? Although efficient, it's not really getting the problem done. If you look at this:
EncryptMessageParams.dwFlags = 0;
EncryptMessageParams.dwInnerContentType = 0;
you will see that it is pre-defined, but used only in the definition of retval. However, I could definitely see this as a micro-optimization, and not really useful if we're going to re-write the code. However, I've outlined the basic steps blow to integrate this without a total re-do of the code (so you can keep on using the same parameters):
Step 2 - Editing the Parameters
As #owlstead mentioned in his comments, the Crypto API is not very user-friendly. However, you've done a great job with limited resources. What you'll wanna add is a Cryptographic Enumeration Provider to help narrow down the keys. Make sure you have either Microsoft Base Cryptographic Provider version 1.0 or Microsoft Enhanced Cryptographic Provider version 1.0 to use these efficiently. Otherwise, you'll need to add in the function like so:
DWORD cbName;
DWORD dwType;
DWORD dwIndex;
CHAR *pszName = NULL;
(regular crypt calls here)
This is mainly used to prevent the NTE_BAD_FLAGS error, although technically you could avoid this with a more low-level declaration. If you wanted, you could also create a whole new hash (although this is only necessary if the above implementation won't scale to the necessary factor of time/speed):
DWORD dwBufferLen = strlen((char *)pbBuffer)+1*(0+5);
HCRYPTHASH hHash;
HCRYPTKEY hKey;
HCRYPTKEY hPubKey;
BYTE *pbKeyBlob;
BYTE *pbSignature;
DWORD dwSigLen;
DWORD dwBlobLen;
(use hash as normal w/ crypt calls and the pbKeyBlobs/Signatures)
Make sure to vaildate this snippet before moving on. You can do so easily like so:
if(CryptAcquireContext(&hProv, NULL, NULL, PROV_RSA_FULL, 0)) {
printf("CSP context acquired.\n");
}
If you're documenting or releasing, might want to add a void MyHandleError(char *s) to catch the error so someone who edits but fails can catch it quickly.
By the way, the first time you run it you'll have to create a new set because there's no default. A nice one-liner that can be popped into an if is below:
CryptAcquireContext(&hCryptProv, NULL, NULL, PROV_RSA_FULL, CRYPT_NEWKEYSET)
Remember that syncing server resources will not be as efficient as doing the re-work I suggested in the first step. This is what I will be explaining below:
Step 3 - Recode and Relaunch
As a programmer, re-coding might seem like a waste of time, but it can definitely help you out in the long run. Remember that you'll still have to code in the custom params when encoding/syncing; I'm not going to hand-feed you all the code like a baby. It should be well sufficient to show you the basic outlines.
I'm definitely assuming that you're trying to handle to the current user's key container within a particular CSP; otherwise, I don't really see the use of this. If not, you can do some basic edits to suit your needs.
Remember, we're going to bypass CryptEncryptMessage by using CryptReleaseContext, which directly releases the handle acquired by the CryptAcquireContext function. Microsoft's standard on the CAC is below:
BOOL WINAPI CryptAcquireContext(
_Out_ HCRYPTPROV *phProv,
_In_ LPCTSTR pszContainer,
_In_ LPCTSTR pszProvider,
_In_ DWORD dwProvType,
_In_ DWORD dwFlags
);
Note that Microsoft's scolding you if you're using a user interface:
If the CSP must display the UI to operate, the call fails and the NTE_SILENT_CONTEXT error code is set as the last error. In addition, if calls are made to CryptGenKey with the CRYPT_USER_PROTECTED flag with a context that has been acquired with the CRYPT_SILENT flag, the calls fail and the CSP sets NTE_SILENT_CONTEXT.
This is mainly server code, and the ERROR_BUSY will definitely be displayed to new users when there are multiple connections, especially those with a high latency. Above 300ms will just cause a NTE_BAD_KEYSET_PARAM or similar to be called, due to the timeout without even a proper error being received. (Transmission problems, anyone with me?)
Unless you're concerned about multiple DLL's (which this doesn't support due to NTE_PROVIDER_DLL_FAIL errors), the basic set up to grab crypt services clientside would be as below (copied directly from Microsoft's examples):
if (GetLastError() == NTE_BAD_KEYSET)
{
if(CryptAcquireContext(
&hCryptProv,
UserName,
NULL,
PROV_RSA_FULL,
CRYPT_NEWKEYSET))
{
printf("A new key container has been created.\n");
}
else
{
printf("Could not create a new key container.\n");
exit(1);
}
}
else
{
printf("A cryptographic service handle could not be "
"acquired.\n");
exit(1);
}
However simple this may seem, you definitely don't want to get stuck passing this on to the key exchange algorithm (or whatever else you have handling this). Unless you're using symmetric session keys (Diffie-Hellman/KEA), the exchange keypair can be used to encrypt session keys so that they can be safely stored and exchanged with other users.
Someone named John Howard has written a nice Hyper-V Remote Management Configuration Utility (HVRemote) which is a large compilation of the techniques discussed here. In addition to using the basic crypts and keypairs, they can be used to permit ANONYMOUS LOGON remote DCOM access (cscript hvremote.wsf, to be specific). You can see many of the functions and techniques in his latest crypts (you'll have to narrow the query) on his blog:
http://blogs.technet.com/b/jhoward/
If you need any more help with the basics, just leave a comment or request a private chat.
Conclusion
Although it's pretty simple once you realize the basic server-side methods for hashing and how the client grabs the "crypts", you'll be questioning why you even tried the encryption during transmits. However, without the crypting clientside, encrypts would definitely be the only secure way to transmit what was already hashed.
Although you might argue that the packets could be decrypted and hashed off the salts, consider that both in-outgoing would have to be processed and stored in the correct timing and order necessary to re-hash clientside.
I'm building a client using dns-sd api from Bonjour. I notice that there is a flag called kDNSServiceFlagsShareConnection that it is used to share the connection of one DNSServiceRef.
Apple site says
For efficiency, clients that perform many concurrent operations may want to use a single Unix Domain Socket connection with the background daemon, instead of having a separate connection for each independent operation. To use this mode, clients first call DNSServiceCreateConnection(&MainRef) to initialize the main DNSServiceRef. For each subsequent operation that is to share that same connection, the client copies the MainRef, and then passes the address of that copy, setting the ShareConnection flag to tell the library that this DNSServiceRef is not a typical uninitialized DNSServiceRef; it's a copy of an existing DNSServiceRef whose connection information should be reused.
There is even an example that shows how to use the flag. The problem i'm having is when I run the program it stays like waiting for something whenever I call a function with the flag. Here is the code:
DNSServiceErrorType error;
DNSServiceRef MainRef, BrowseRef;
error = DNSServiceCreateConnection(&MainRef);
BrowseRef = MainRef;
//I'm omitting when I check for errors
error = DNSServiceBrowse(&MainRef, kDNSServiceFlagsShareConnection, 0, "_http._tcp", "local", browse_reply, NULL);
// After this call the program stays waiting for I don't know what
//I'm omitting when I check for errors
error = DNSServiceBrowse(&BrowseRef, kDNSServiceFlagsShareConnection, 0, "_http._tcp", "local", browse_reply, NULL);
//I'm omitting when i check for errors
DNSServiceRefDeallocate(BrowseRef); // Terminate the browse operation
DNSServiceRefDeallocate(MainRef); // Terminate the shared connection
Any ideas? thoughts? suggestion?
Since there are conflicting answers, I dug up the source - annotations by me.
// If sharing...
if (flags & kDNSServiceFlagsShareConnection)
{
// There must be something to share (can't use this on the first call)
if (!*ref)
{
return kDNSServiceErr_BadParam;
}
// Ref must look valid (specifically, ref->fd)
if (!DNSServiceRefValid(*ref) ||
// Most operations cannot be shared.
((*ref)->op != connection_request &&
(*ref)->op != connection_delegate_request) ||
// When sharing, pass the ref from the original call.
(*ref)->primary)
{
return kDNSServiceErr_BadReference;
}
The primary fiels is explained elsewhere:
// When using kDNSServiceFlagsShareConnection, there is one primary _DNSServiceOp_t, and zero or more subordinates
// For the primary, the 'next' field points to the first subordinate, and its 'next' field points to the next, and so on.
// For the primary, the 'primary' field is NULL; for subordinates the 'primary' field points back to the associated primary
The problem with the question is that DNSServiceBrowse maps to ref->op==browse_request which causes a kDNSServiceErr_BadReference.
It looks like kDNSServiceFlagsShareConnection is half-implemented, because I've also seen cases in which it works - this source was found by tracing back when it didn't work.
Service referenses for browsing and resolving may unfortunately not be shared. See the comments in the Bonjour documentation for the kDNSServiceFlagsShareConnection-flag. Since you only browse twice I would just let them have separate service-refs instead.
So both DNSServiceBrowse() and DNSServiceResolve() require an unallocated service-ref as first parameter.
I can't explain why your program chokes though. The first DNSServiceBrowse() call in your example should return immediately with an error code.
Although an old question, but it should help people looking around for answers now.
The answer by vidtige is incorrect, the may be shared for any operation, provided you pass the 'kDNSServiceFlagsShareConnection' flag along with the arguments. Sample below -
m_dnsrefsearch = m_dnsservice;
DNSServiceErrorType mdnserr = DNSServiceBrowse(&m_dnsrefsearch,kDNSServiceFlagsShareConnection,0,
"_workstation._tcp",NULL,
DNSServiceBrowseReplyCallback,NULL);
Reference - http://osxr.org/android/source/external/mdnsresponder/mDNSShared/dns_sd.h#0267