Mbed Cortex-m hardfault when sending data via TCP - tcp

Question

I have a TCPSocket* object which holds a connection to a client. This object is passed to another object to send data back to the client:
uint32_t count = 10;
char* message = new char[4];
message[0] = count & 0xff;
message[1] = (count >> 8) & 0xff;
message[2] = (count >> 16) & 0xff;
message[3] = (count >> 24) & 0xff;
client->send(&message, 4);
When this part of the program is called, the following appears on the serial line, and no data is received by the client:
++ MbedOS Fault Handler ++
FaultType: HardFault
Context:
R0 : 00000000
R1 : 10008000
R2 : 00000004
R3 : 2007C000
R4 : 10000914
R5 : 00000000
R6 : 00000000
R7 : 10004330
R8 : 10004320
R9 : FFFFF435
R10 : 00000000
R11 : 00000000
R12 : 00012AC1
SP : 10002AF0
LR : 0000D1A1
PC : 00005938
xPSR : 21000000
PSP : 10002AD0
MSP : 10007FD8
CPUID: 412FC230
HFSR : 40000000
MMFSR: 00000000
BFSR : 00000082
UFSR : 00000000
DFSR : 0000000A
AFSR : 00000000
BFAR : 10008010
Mode : Thread
Priv : Privileged
Stack: PSP
-- MbedOS Fault Handler --
++ MbedOS Error Info ++
Error Status: 0x80FF013D Code: 317 Module: 255
Error Message: Fault exception
Location: 0xD337
Error Value: 0x5938
Current Thread: main Id: 0x10002B48 Entry: 0xD7D7 StackSize: 0x1000 StackMem: 0x10001B48 SP: 0x10007F88
For more info, visit: https://armmbed.github.io/mbedos-error/?error=0x80FF013D
-- MbedOS Error Info --
Everything is in one thread so I cant see what could be causing this.
These are the relevant parts of the program:
main:
// Network interface
EthernetInterface net;
TCPSocket listener; //listens for incoming connection requests
TCPSocket* client;
CommandProcessor commandProcessor(client);
int main() {
int remaining;
int rcount;
char *p;
char *buffer = new char[16];
nsapi_size_or_error_t result;
int n = net.set_network("192.168.1.103","255.255.255.0","192.168.1.2");
pc.printf("\n Success? %d\n", n);
net.connect();
listener.open(&net);
listener.bind(3045);
listener.listen(1);
client = listener.accept(NULL);
client->set_timeout(1000);
led1 = 1;
while(1) {
int remaining = 16;
int rcount = 0;
p = buffer;
while (remaining > 0 && 0 < (result = client->recv(p, remaining))) {
p += result;
rcount += result;
remaining -= result;
}
if (remaining == 0) //full message received
{
commandProcessor.process(buffer);
}
}
}
CommandProcessor:
CommandProcessor::CommandProcessor(TCPSocket* client)
{
this->client = client;
}
void CommandProcessor::process(char* message)
{
switch(message[0]) { //Command is first byte of message
case 0x3: {
uint32_t count = 10 ;
char* message = new char[4];
message[0] = count & 0xff;
message[1] = (count >> 8) & 0xff;
message[2] = (count >> 16) & 0xff;
message[3] = (count >> 24) & 0xff;
client->send(message, 4);
}
}
}

Answer 1

commandProcessor's client is NULL when you call commandProcessor.process(buffer).
Why don’t you create an instance of CommandProcessor after you get a pointer to a socket from accept().
CommandProcessor* commandProcessor;
client = listener.accept(NULL);
commandProcessor = new CommandProcessor(client);
commandProcessor->process(buffer);
Alternatively, you can set client with a function like this.
void CommandProcessor::setClient(TCPSocket* client) {
this->client = client;
}
usage:
client = listener.accept(NULL);
commandProcessor.setClient(client);