Hi again, i have one more question if you dont mind. My client runs ok now, althrough now i also need to write a server. So I do, but in one of the lines i am receiving segmentation error, which i understand is an event that occurs when i try to acces memory that doesnt exist(?)
And this happens at this line:
without it i can connect to my server and receive answer properly, but receiving answer from dict.org server is faulty.
I have to honest with you, im not sure what is the need for this line.
Would you mind explaining it?
Here is the code of my very early server:
Code:
#include<stdio.h>
#include<string.h> //strlen
#include<stdlib.h> //strlen
#include<sys/socket.h>
#include<arpa/inet.h> //inet_addr
#include<unistd.h> //write
#include<pthread.h> //for threading , link with lpthread
void *connection_handler(void *);
int main(int argc , char *argv[])
{
int socket_desc , new_socket , c , *new_sock;
struct sockaddr_in server , client;
char *message;
//Create socket
socket_desc = socket(AF_INET , SOCK_STREAM , 0);
if (socket_desc == -1)
{
printf("Could not create socket");
}
//Prepare the sockaddr_in structure
server.sin_family = AF_INET;
server.sin_addr.s_addr = INADDR_ANY;
server.sin_port = htons( 8888 );
//Bind
if( bind(socket_desc,(struct sockaddr *)&server , sizeof(server)) < 0)
{
puts("bind failed");
return 1;
}
puts("bind done");
//Listen
listen(socket_desc , 3);
//Accept and incoming connection
puts("Waiting for incoming connections...");
c = sizeof(struct sockaddr_in);
while( (new_socket = accept(socket_desc, (struct sockaddr *)&client, (socklen_t*)&c)) )
{
puts("Connection accepted");
pthread_t sniffer_thread;
new_sock = malloc(1);
*new_sock = new_socket;
if( pthread_create( &sniffer_thread , NULL , connection_handler , (void*) new_sock) < 0)
{
perror("could not create thread");
return 1;
}
//Now join the thread , so that we dont terminate before the thread
//pthread_join( sniffer_thread , NULL);
puts("Handler assigned");
}
if (new_socket<0)
{
perror("accept failed");
return 1;
}
return 0;
}
/*
* This will handle connection for each client
* */
void *connection_handler(void *socket_desc)
{
//Get the socket descriptor
int sock = *(int*)socket_desc;
int read_size;
char *message , client_message[2000];
//Send messages to the client that he is connected
message = "220 Connected to Aleksandra Gut dict server\r\n";
write(sock , message , strlen(message));
//Receive a message from client
// while( (read_size = recv(sock , client_message , 2000 , 0)) > 0 )
// {
// //Send the message back to client
// write(sock , client_message , strlen(client_message));
// puts(client_message);
// }
read_size = recv(sock , client_message , 2000 , 0);
puts("Received message from client:");
puts(client_message);
//Send message to the client how many definitions has been found.
message = "150 1 definition retrieved\r\n";
write(sock , message , strlen(message));
//Send definition to the client.
message = "151 Definicja Pingwina yo\nDefinicja Pingwina yo\nDefinicja Pingwina yo\n\r\n.\r\n250";
write(sock , message , strlen(message));
read_size = recv(sock , client_message , 2000 , 0);
//Send finish connection to the client.
message = "221 bye \r\n";
write(sock , message , strlen(message));
if(read_size == 0)
{
puts("Client disconnected");
fflush(stdout);
}
else if(read_size == -1)
{
perror("recv failed");
}
//Free the socket pointer
free(socket_desc);
return 0;
}
And this is my client that works for what i need pretty well: (but not for connecting to the server i wrote. only after commenting the problem line):
Code:
#include<stdio.h>
#include<string.h> //strlen
#include<sys/socket.h>
#include<arpa/inet.h> //inet_addr
#include <unistd.h>
#define WORLD_2_SEND "DEFINE * penguin\r\n"
#define ADDRESS "216.18.20.172" // dict.org
#define PORT 2628
int socket_desc;
struct sockaddr_in server;
char server_reply[500000];
char prefix[3];
//char nrOfDefinitionsFound[1];
//unsigned int nrOfDefsInt = 0;
void Close_Connection (void);
void Print_Answers (void);
int main(void)
{
//Create socket
socket_desc = socket(AF_INET , SOCK_STREAM , 0);
if (socket_desc == -1)
{
printf("Could not create socket");
}
server.sin_addr.s_addr = inet_addr(ADDRESS);
server.sin_family = AF_INET;
server.sin_port = htons(PORT);
//Connect to remote server
if (connect(socket_desc , (struct sockaddr *)&server , sizeof(server)) < 0)
{
puts("connect error");
return 1;
}
puts("Connected");
recv(socket_desc, server_reply , sizeof(server_reply) , 0);
puts("Server answered with:");
puts(server_reply);
memset(server_reply, 0, sizeof(server_reply));
puts("Now it's time for sending a request");
send(socket_desc, WORLD_2_SEND, strlen(WORLD_2_SEND), 0);
puts("Server returned 1:");
recv(socket_desc, server_reply, sizeof(server_reply), 0);
memcpy(prefix, server_reply, sizeof(char) * 3);
if (0 == strcmp("150", prefix))
{
puts(server_reply);
// nrOfDefinitionsFound[0] = server_reply[4];
// nrOfDefsInt = nrOfDefinitionsFound[0] - '0';
// printf("defs found = %u\n", nrOfDefsInt);
Print_Answers();
}
else if (0 == strcmp("552", prefix))
{
puts(server_reply);
Close_Connection();
return 1;
}
Close_Connection();
return 0;
}
void Close_Connection (void)
{
send(socket_desc, "QUIT\r\n", 6, 0);
memset(server_reply, 0, sizeof(server_reply));
recv(socket_desc, server_reply, sizeof(server_reply), 0);
puts("Connection closed, server replied with:");
puts(server_reply);
close(socket_desc);
}
void Print_Answers (void)
{
puts("Server returned 2:");
ssize_t ret, len = 0;
char answer[5000000];
char *pos = answer;
while ((ret = recv(socket_desc, server_reply , sizeof(server_reply) , 0)))
{
strncat(answer, server_reply, 5000000 - len);
len += ret;
if ((pos = strstr(pos, "\r\n.\r\n250")))
{
pos = strstr(pos + strlen(WORLD_2_SEND), "\n");
*(pos + 1) = '\0';
break;
}
else
pos = answer + len;
}
puts(answer);
}
I hope this isnt to much already, but i would rly aprichiate if you could explain me this issue.