I'm struggling with an issue where an ESP32 is running as a AP with AsyncTCP connecting multiple ESP32 clients. The AP receives some JSON data and replies with some JSON data. Without the handleData() function, the code runs 100% fine with no issues. Heap is static when no clients connect and issues only occur when clients start connecting.
Can anyone see anything with my code that could be causing heap corruption or other memory weirdness?
static void handleData(void* arg, AsyncClient* client, void *data, size_t len) {
int i = 0, j = 0;
char clientData[CLIENT_DATA_MAX];
char packetData[len];
char *packetBuf;
packetBuf = (char *)data;
clientData[0] = '\0';
for (i=0;i <= len;i++) {
packetData[j] = packetBuf[i]; //packetBuf[i];
if ((packetData[j] == '\n') || (i == len)) {
packetData[j] = '\0';
if ((j > 0) && (packetData[0] != '\n') && (packetData[0] != '\r')) {
// See sensorData() below...
parseData.function(packetData, clientData);
if (clientData != NULL) {
// TCP reply to client
if (client->space() > 32 && client->canSend()) {
client->write(clientData);
}
}
}
j = 0;
} else
j++;
}
}
void sensorData(void *data, void *retData) {
StaticJsonDocument<CLIENT_DATA_MAX> fields;
StaticJsonDocument<CLIENT_DATA_MAX> output;
char sensor[15] = "\0";
char MAC[18] = "\0";
char value[20] = "\0";
bool sendOK = false;
memcpy((char *)retData, "\0", 1);
DeserializationError error = deserializeJson(fields, (char *)data, CLIENT_DATA_MAX);
if (error) {
DEBUG_PRINTLN(F("deserializeJson() failed"));
return;
}
if (fields["type"])
strcpy(sensor, fields["type"]);
switch (sensor[0]) {
case 'C':
if (fields["value"])
strcpy(value, fields["value"]);
sendOK = true;
break;
case 'T': //DEBUG_PRINT(F("Temp "));
setExtTempSensor(fields["value"]);
sendOK = true;
break;
case 'N':
output["IT"] = intTempC; //Internal temp
output["B1"] = battLevels[0];
serializeJson(output, (char *)retData, CLIENT_DATA_MAX-1);
break;
}
if (sendOK) {
output["Resp"] = "Ok";
serializeJson(output, (char *)retData, CLIENT_DATA_MAX-1);
}
strcat((char *)retData, "\n");
}
static void handleNewClient(void* arg, AsyncClient* client) {
client->setRxTimeout(1000);
client->setAckTimeout(500);
client->onData(&handleData, NULL);
client->onError(&handleError, NULL);
client->onDisconnect(&handleDisconnect, NULL);
client->onTimeout(&handleTimeOut, NULL);
}
void startServer() {
server = new AsyncServer(WIFI_SERVER_PORT);
server->onClient(&handleNewClient, &server)
}
Using AsyncTCP on the ESP32 was having multiple issues. Heap issues, socket issues, assert issues, ACK timeouts, connection timeouts, etc. Swapping to AsyncUDP using the exact same code as shown above with romkey's changes, resolved all of my issues. (Just using romkey's fixes did not fix the errors I was having with AsyncTCP.) I don't believe the issue is with AsyncTCP but with ESP32 libraries.
Either you should declare packetData to be of length len + 1 or your for loop should iterate until i < len. Because the index starts at 0, packetData[len] is actually byte len + 1, so you'll overwrite something random when you store something in packetData[len] if the array is only len chars long.That something random may be the pointer stored in packetBuf, which could easily cause heap corruption.
You should always use strncpy() and never strcpy(). Likewise use strncat() rather than strcat(). Don't depend on having done the math correctly or on sizes not changing as your code evolves. strncpy() and strncat() will guard against overflows. You'll need to pass a length into sensorData() to do that, but sensorData() shouldn't be making assumptions about the available length of retData.
Your test
if (clientData != NULL) {
will never fail because clientData is the address of array and cannot change. I'm not sure what you're trying to test for here but this if will always succeed.
You can just write:
char sensor[15] = "";
you don't need to explicitly assign a string with a null byte in it.
And
memcpy((char *)retData, "\0", 1);
is equivalent to
((char *)retData)[0] = '\0';
What's the point of declaring retData to be void * in the arguments to sensorData()? Your code starts out with it being a char* before calling sensorData() and uses it as a char* inside sensorData(). void * is meant to be an escape hatch for passing around pointers without worrying about their type. You don't need that here and end up needing to extra casts back to char* because of it. Just declare the argument to be char* and don't worry about casting it again.
You didn't share the code that calls handleData() so there may well be issues outside of these functions.
Related
Hi I tried to write my own version of memmove and I find the following code resulting in a segmentation fault. It would be great if someone could help me figure out why this behavior would occur!
However, when I use something like:
char source[20] = "Hello, this is Piranava", the code works fine!
void *memmoveLocal(void *dest, const void *src, unsigned int n)
{
char *destL = dest;
const char *srcL = src;
int i = 0;
if(dest == NULL || src == NULL)
{
return NULL;
}
else
{
// if dest comes before source, even if there's an overlap, we should move forward
// because if there's an overlap (when dest < src) and we move backward, we'd overwrite the overlapping bytes in src
if(destL < srcL)
{
printf("Forward\n");
while(i < n)
{
destL[i] = srcL[i];
i++;
}
}
else // in all other cases (even if there's overlap or no overlap, we can move backward)
{
printf("Backward\n");
i = n - 1;
while(i >= 0)
{
destL[i] = srcL[i];
i--;
}
}
}
return dest;
}
void main()
{
char *source = "Hello, this is ABC";
char *destination = malloc(strlen(source)+1);
memmoveLocal(source+5, source, 5);
printf("Source: %s \nDestination: %s, size: %d\n", source, destination, strlen(destination));
}
However, if I replace
char *source = "Hello, this is ABC";
with
char source[20] = "Hello, this is ABC";
, it works fine!
memmoveLocal(source+5, source, 5);
You are trying to overwrite a string literal, which is not writable.
Did you intend to memmoveLocal(destination, source+5, 5) instead?
char source[20] = "Hello, this is ABC";
That turns source from a string literal into a char[] array initialized with a string literal. The array is writable, so your program no longer crashes.
I recently started using Arduino so I still have to adapt and find the differences between C/C++ and the Arduino language.
So I have a question for you.
When I see someone using a C-style string in Arduino (char *str), they always initialize it like this (and never free it) :
char *str = "Hello World";
In pure C, I would have done something like this:
int my_strlen(char const *str)
{
int i = 0;
while (str[i]) {
i++;
}
return (i);
}
char *my_strcpy(char *dest, char const *src)
{
char *it = dest;
while (*src != 0) {
*it = *src;
it++;
src++;
}
return (dest);
}
char *my_strdup(char const *s)
{
char *result = NULL;
int length = my_strlen(s);
result = my_malloc(sizeof(char const) * (length + 1));
if (result == NULL) {
return (NULL);
}
my_strcpy(result, s);
return (result);
}
and then initialize it like this:
char *str = my_strdup("Hello World");
my_free(str);
So here is my question, on C-style Arduino strings, is malloc optional or these people just got it wrong?
Thank you for your answers.
In C++ it's better to use new[]/delete[] and not mix it with malloc/free.
In the Arduino there is also String class, that hides those allocations from you.
However using dynamic memory allocations in such restrained platform has its pitfalls, like heap fragmentation (mainly because String overloads + operator, so everyone is overusing it like: Serial.println(String{"something : "} + a + b + c + d + ......) and then wonders about mysterious crashes.
More about it on Majenko's blog: The Evils of Arduino String class (Majenko has highest reputation on the arduino stackexchange)
Basically with the String class your strdup code would be simple as this:
String str{"Hello World"};
String copyOfStr = str;
I've written this code to receive a series of char variable through USART6 and have them stored in a string. But the problem is first received value is just a junk! Any help would be appreciated in advance.
while(1)
{
//memset(RxBuffer, 0, sizeof(RxBuffer));
i = 0;
requestRead(&dt, 1);
RxBuffer[i++] = dt;
while (i < 11)
{
requestRead(&dt, 1);
RxBuffer[i++] = dt;
HAL_Delay(5);
}
function prototype
static void requestRead(char *buffer, uint16_t length)
{
while (HAL_UART_Receive_IT(&huart6, buffer, length) != HAL_OK)
HAL_Delay(10);
}
First of all, the HAL_Delay seems to be redundant. Is there any particular reason for it?
The HAL_UART_Receive_IT function is used for non-blocking mode. What you have written seems to be more like blocking mode, which uses the HAL_UART_Receive function.
Also, I belive you need something like this:
Somewhere in the main:
// global variables
volatile uint8_t Rx_byte;
volatile uint8_t Rx_data[10];
volatile uint8_t Rx_indx = 0;
HAL_UART_Receive_IT(&huart1, &Rx_byte, 1);
And then the callback function:
void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart)
{
if (huart->Instance == UART1) { // Current UART
Rx_data[Rx_indx++] = Rx_byte; // Add data to Rx_Buffer
}
HAL_UART_Receive_IT(&huart1, &Rx_byte, 1);
}
The idea is to receive always only one byte and save it into an array. Then somewhere check the number of received bytes or some pattern check, etc and then process the received frame.
On the other side, if the number of bytes is always same, you can change the "HAL_UART_Receive_IT" function and set the correct bytes count.
My chip just stop doing anything. sometimes it prints good results, sometimes its not, i just cant understand whats wrong with this code( and generally any time you using Strings it happens )
void ParseGetRequest(char* data)
{
String parseGET=data;
String from="GET /";
String to="HTTP";
int ind1 = parseGET.indexOf(from);
int ind2 = parseGET.indexOf(to);
parseGET=parseGET.substring(ind1+from.length(), ind2-1);
strcpy(data, parseGET.c_str () );
}
And calling it with :
void readWifDataAsSever(char* reqData)
{
uint8_t buffer[128] = {0};
uint8_t mux_id;
uint32_t len = wifi.recv(&mux_id, buffer, sizeof(buffer), 100);
char serverData[100]={0};
if (len > 0)
{
for(uint32_t i = 0; i < len; i++)
serverData[i]=(char)buffer[i];
ParseGetRequest( serverData ); ///****** the call
Serial.println(serverData); // prints only part of the values
//here the chip just freeze and stop the main loop
NULL termination !!!!
serverData[len ] = '\0';
I am currently making a simple client and server but I have run into an issue. Part of the system is for the client to query about a local file on the server. The contents of that file must be then sent to the client. I am able to send all the text within a file to the client however it seems to be stuck in the read loop on the client. Below are the code spits for both the client and server that are meant to deal with this:
Client Code That Reads The Loop
else if(strcmp(commandCopy, get) == 0)
{
char *ptr;
int total = 0;
char *arguments[1024];
char copy[2000];
char * temp;
int rc;
strcpy(copy, command);
ptr = strtok(copy," ");
while (ptr != NULL)
{
temp = (char *)malloc(sizeof(ptr));
temp = ptr;
arguments[total] = temp;
total++;
ptr = strtok (NULL, " ");
}
if(total == 4)
{
if (strcmp(arguments[2], "-f") == 0)
{
printf("1111111111111");
send(sockfd, command, sizeof(command), 0 );
printf("sent %s\n", command);
memset(&command, '\0', sizeof(command));
cc = recv(sockfd, command, 2000, 0);
if (cc == 0)
{
exit(0);
}
}
else
{
printf("Here");
strcpy(command, "a");
send(sockfd, command, sizeof(command), 0 );
printf("sent %s\n", command);
memset(&command, '\0', sizeof(command));
cc = recv(sockfd, command, 2000, 0);
}
}
else
{
send(sockfd, command, sizeof(command), 0 );
printf("sent %s\n", command);
memset(&command, '\0', sizeof(command));
while ((rc = read(sockfd, command, 1000)) > 0)
{
printf("%s", command);
}
if (rc)
perror("read");
}
}
Server Code That Reads the File
char* getRequest(char buf[], int fd)
{
char * ptr;
char results[1000];
int total = 0;
char *arguments[1024];
char data[100];
FILE * pFile;
pFile = fopen("test.txt", "r");
ptr = strtok(buf," ");
while (ptr != NULL)
{
char * temp;
temp = (char *)malloc(sizeof(ptr));
temp = ptr;
arguments[total] = temp;
total++;
ptr = strtok (NULL, " ");
}
if(total < 2)
{
strcpy(results, "Invaild Arguments \n");
return results;
}
if(pFile != NULL)
{
while(fgets(results, sizeof(results), pFile) != NULL)
{
//fputs(mystring, fd);
write(fd,results,strlen(results));
}
}
else
{
printf("Invalid File or Address \n");
}
fclose(pFile);
return "End of File \0";
}
Server Code to execute the command
else if(strcmp(command, "get") == 0)
{
int pid = fork();
if (pid ==-1)
{
printf("Failed To Fork...\n");
return-1;
}
if (pid !=0)
{
wait(NULL);
}
else
{
char* temp;
temp = getRequest(buf, newsockfd);
strcpy(buf, temp);
send(newsockfd, buf, sizeof(buf), 0 );
exit(1);
}
}
The whole else if clause in the client code is a bit large for a function, let alone a part of a function as it presumably is. The logic in the code is ... interesting. Let us dissect the first section:
else if (strcmp(commandCopy, get) == 0)
{
char *ptr;
int total = 0;
char *arguments[1024];
char *temp;
ptr = strtok(copy, " ");
while (ptr != NULL)
{
temp = (char *)malloc(sizeof(ptr));
temp = ptr;
arguments[total] = temp;
total++;
ptr = strtok(NULL, " ");
}
I've removed immaterial declarations and some code. The use of strtok() is fine in context, but the memory allocation is leaky. You allocate enough space for a character pointer, and then copy the pointer from strtok() over the only pointer to the allocated space (thus leaking it). Then the pointer is copied to arguments[total]. The code could, therefore, be simplified to:
else if (strcmp(commandCopy, get) == 0)
{
char *ptr;
int total = 0;
char *arguments[1024];
ptr = strtok(copy, " ");
while (ptr != NULL)
{
arguments[total++] = ptr;
ptr = strtok(NULL, " ");
}
Nominally, there should be a check that you don't overflow the arguments list, but since the original limits the string to 2000 characters, you can't have more than 1000 arguments (all single characters separated by single spaces).
What you have works - it achieves the same assignment the long way around, but it leaks memory prodigiously.
The main problem seems to be that the server sends all the contents, but it doesn't close the socket, so the client has no way of knowing the server's done. If you close the socket after you finish sending the data (or just call shutdown()), then the client's read() will return 0 when it finishes reading the data.
FWIW, there are lots of other problems with this code:
getRequest: you call malloc but never free. In fact, the return value is thrown away.
Why bother forking if you're just going to wait() on the child?
You probably want to use strlcpy instead of strpcy to avoid buffer overruns.