Thread: Problem with my program.

Code:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <netdb.h>

#define MYPORT 9034

int main(void)
{
	int sockfd;
	char ch;
	struct sockaddr_in my_addr, their_addr;
	char buffer[1000];
	
	sockfd = socket(AF_INET, SOCK_STREAM, 0);
	if(sockfd == -1)
	{
		printf("ERROR!!");
		perror("socket");
		getchar();
		exit(1);
	}
	
        my_addr.sin_family = AF_INET;
        my_addr.sin_addr.s_addr = INADDR_ANY;
        my_addr.sin_port = htons(MYPORT);
        memset(&(my_addr.sin_zero), '\0', 8);
		if( (bind(sockfd,(struct sockaddr *)&my_addr,sizeof(struct sockaddr)))==-1)    
		{         
			perror("bind");
            exit(1);
        }
	
	if( listen(sockfd, 10) == -1 )
	{
		printf("ERROR!!");
		perror("listen");
		getchar();
		exit(1);
	}
	
	scanf("&#37;c", &ch);
	while( ch != 'q')
	{
		int state = sizeof(struct sockaddr);
		int new_fd = accept(sockfd, (struct sockaddr *)&their_addr, &state);
		if(new_fd == -1)
		{
			perror("accept");
			exit(1);
		}
		
                state = send(new_fd, buffer, strlen(buffer), 0);
		sprintf(buffer, "%s has connected.\n", inet_ntoa(their_addr.sin_addr));
		if(state == -1)
		{	
		printf("ERROR!!");
		perror("send");
		getchar();
		exit(1);
		}
	}
	
	return 0;
}

ERRORS:

Code:

untitled.c:49: warning: pointer targets in passing argument 3 of ‘accept’ differ in signedness
untitled.c:56: warning: implicit declaration of function ‘inet_ntoa’
untitled.c:56: warning: format ‘%s’ expects type ‘char *’, but argument 3 has type ‘int’

The compilation was finished successfully though but it doesn't work properly.

How to fix it?
I might be missing some headers.

BTW,
Is there any other function that I could get 1 character? fgets doesn't work for characters just for strings, and gets & scanf are dangerous.
Any suggestions?

The first problem is that "state" should be a socklen_t type.

And yes, the second problem is missing include file(s). Check up the inet_ntoa.

--
Mats

Originally Posted by matsp

The first problem is that "state" should be a socklen_t type.

And yes, the second problem is missing include file(s). Check up the inet_ntoa.

--
Mats

Socket length? strlen?
#include <arpa/inet.h>

why do I need to cast it to struct sockaddr? why to cast and why sockaddr and not sockaddr_in?
also, why I have to type & before state and this casting thing and many others?
why is there a struct sockaddr_in their_addr and then I cast it? and in the cast & is added? why is this casted to be a pointer?
why is state stores accept too? it stores the size of sockaddr.
why do I need the size of sockaddr?
why do I need sin_zero?

memset(&(my_addr.sin_zero), '\0', 8);
again, why & is added?

basically, these are whole of my questions, im reading Beej's book.
I'll try to see if I have more questions.

thank you for your time and patience

edit:
It doesn't work :S

socklen_t is a typedef of some type that is unsigned. So you SHOULD use "socklen_t share" rather than "int share".

As to the other questions, I don't know much about socket programming, so I can't comment on most.

You need the & to get an address for memset, so that you can fill an area of memory with zero bytes.

--
Mats

Originally Posted by matsp

socklen_t is a typedef of some type that is unsigned. So you SHOULD use "socklen_t share" rather than "int share".

As to the other questions, I don't know much about socket programming, so I can't comment on most.

You need the & to get an address for memset, so that you can fill an area of memory with zero bytes.

--
Mats

Could anyone answer these please?

and btw,
Is there any other function that I could get 1 character? fgets doesn't work for characters just for strings, and gets & scanf are dangerous.
maybe getchar();?

Originally Posted by eXeCuTeR

Could anyone answer these please?

and btw,
Is there any other function that I could get 1 character? fgets doesn't work for characters just for strings, and gets & scanf are dangerous.

fgetc()?

--
Mats

finally works
btw, if any of you could still answer my questions ill be SO THANKFUL!

Code:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <unistd.h>

#define MYPORT 6666

int main(int argc, char *argv[])
{
	int sockfd, new_fd; // file descriptions: sockfd to create a connection, and new_fd to send and receive data.
	char ch; // if q is pressed then stop the program
	struct sockaddr_in my_addr; // server's info
	struct sockaddr_in their_addr; // client's info
	char buffer[1000]; // buffer for the output
	socklen_t state;
	
	sockfd = socket(AF_INET, SOCK_STREAM, 0);
	if(sockfd == -1)	{
		perror("socket");
		exit(1);
	}
	
        my_addr.sin_family = AF_INET;
        my_addr.sin_addr.s_addr = htonl(INADDR_ANY);
        my_addr.sin_port = htons(MYPORT);
        memset(&(my_addr.sin_zero), '\0', 8);
        
		if( bind(sockfd, (struct sockaddr *)&my_addr, sizeof(struct sockaddr)) == -1)	{         
			perror("bind");
            exit(1);
        }
	
	if( listen(sockfd, 10) == -1 )	{
		perror("listen");
		exit(1);
	}
	
	while(ch != 'q')
	{
		state = sizeof(struct sockaddr);
		new_fd = accept(sockfd, (struct sockaddr *)&their_addr, &state);
		if(new_fd == -1)	{
			perror("accept");
			exit(1);
		}
		
		state = send(new_fd, buffer, strlen(buffer), 0);
        printf("Your IP is: &#37;s\n", inet_ntoa(their_addr.sin_addr));
		sprintf(buffer, "%s has connected.\n", inet_ntoa(their_addr.sin_addr));
		if(state == -1)
			printf("Couldn't send the message.\n");
		
		printf("Press 'q' to quit.\n");
		ch = getchar();
		putchar(ch);
		close(new_fd);
	}
	close(sockfd);
	return 0;
}

Originally Posted by Aia

Didn't he answer your question? What other question are you seeking answer for?

why do I need to cast it to struct sockaddr? why to cast and why sockaddr and not sockaddr_in?
also, why I have to type & before state and this casting thing and many others?
why is there a struct sockaddr_in their_addr and then I cast it? and in the cast & is added? why is this casted to be a pointer?
why do I need the size of sockaddr?
why do I need sin_zero?

Do you understand pointers?
If you didn't use &, it would simply pass a local copy to the function which it modifies and which does not reflect its value back in your function, so you need to pass a pointer, hence you pass the address of the variable to make it a pointer.

If you understand pointers, and my reply, then you should understand that passing a non-pointer to memset would make no sense. Additionally, here's the prototype of memset:

void *memset(void *dest, int c, size_t count);

Originally Posted by Elysia

If you understand pointers, and my reply, then you should understand that passing a non-pointer to memset would make no sense. Additionally, here's the prototype of memset:

I know how memset works but I'm talking about accept and the others.

edit: lol, I forgot to delete this question.

You did ask about memset, and I did reply.
As for accept - all I know is that its declaration is:

Code:

SOCKET accept(
  __in          SOCKET s,
  __out         struct sockaddr* addr,
  __in_out      int* addrlen
);

Actually, it is declared as socketaddr* for backwards compability, and does not strictly want a socketaddr structure. So if you pass something else, you need to cast it because socketaddr != socketaddr_in.