Pthreads help

Hi I have built a simple web server in C, and I now have to make it multi threaded. I also have to produce a multi threaded command line client to test the multi-threaded capability of the server. I have finished the client and the server however I get read errors when making more than 1 request to the server. I believe it is because I need to look some resources with mutexes but I'm not quite sure how and where to do it.

Code:

---

while (1) {
    //Accept new connection and fork
    remote_len = sizeof(remote_addr);
    sd = accept(lsd, (struct sockaddr *) &remote_addr, &remote_len);
    printf("Connection Received!\n");
    //Store remote IP in "inetadddr" for error logging
    inet_ntop(AF_INET, &(remote_addr.sin_addr), inetaddr, INET_ADDRSTRLEN);
    if (sd < 0) {
      logerrors("Socket Error: Cannot accept connection from",inetaddr);
    }
    params->sd = sd;
    params->inetaddr = inetaddr;
    threadr = pthread_create(&thread[i++], NULL, web, (void*) params);

---

That is the accept code in main and the new thread starts with web function:

Code:

---

void *web (void *arg)
{
  int n, sd;
  char buffer[BUFFERSIZE];
  char *inetaddr;
 
  struct funcparams *params = (void *) arg;
  sd = params->sd;
  inetaddr = params->inetaddr;
 
  bzero(buffer, BUFFERSIZE);
  //Read browser request
  n = read(sd,buffer,BUFFERSIZE);

---

So this read request fails, well it works for the first connection then fails on the rest. Like I said i'm sure its because I need to lock the resources sd and inetaddr but i'm not sure where to lock and unlock. Any help would be greatly appreciated

You really need

params = malloc( sizeof *params );

If your params is anything else (pointer to a local, an array of some sort), then MULTIPLE threads are going to end up referencing the same (or possibly non-existent) block of memory.

The malloc is before the accept loop, it is there:

Code:

---

params = (struct funcparams *) malloc(sizeof(struct funcparams));

---

The struct is:

Code:

---

struct funcparams {
        int sd;
        char *inetaddr;
};

---

>> The malloc is before the accept loop
It needs to be in the loop - each thread gets its own parameters. You're passing a shallow copy of 'inetaddr' too. That needs to be a unique pointer per-thread as well.

gg

I don't understand what you mean, can you elaborate please?

OK I got it working now, thanks