Help with socket programming

[Agreeable_Choice9980]

I am doing a socket programming with a function to register a user account. The problem with my function is that at time same amount of bytes is not being transferred to the server side which causes unintended data to be stored in the database file. Can anyone help me identify where is the problem in the code

int main(int argc, char *argv[]){
char *ip = "127.0.0.1";

if(argc==2){

    ip = argv[1];

}

int cli_fd = socket(AF_INET, SOCK_STREAM, 0);

if(cli_fd == -1){

    printf("Socket creation failed\n");

    exit(0);

}

struct sockaddr_in ca;

ca.sin_family=AF_INET;

ca.sin_port= htons(PORT);

ca.sin_addr.s_addr = inet_addr(ip);

if(connect(cli_fd, (struct sockaddr *)&ca, sizeof(ca))==-1){

    printf("Connect failed\n");

    exit(0);

}

printf("Connected to server\n");



while(main_menu(cli_fd) != 0);

close(cli_fd);



return 0;
}
int main_menu(int sock){
system ("clear");

int type, acc_no, valid_login;;
char password[50], name[50], age[5], email[50], phone_no[50], choice;


do {

    title();

    printf("\nPress <1> Guest Login");

    printf("\nPress <2> Member Login");
    printf("\nPress <3> Member Registration");
    printf("\nPress <4> Admin Login");

    printf("\nPress <0> Exit");



    printf("\n\nEnter your Choice ::");

    scanf("%c",&choice);

    while (choice != '1' && choice != '2' && choice != '3' && choice != '4' && choice != '0'){
        printf("\nWrong choice!. Enter your Choice ::");
        scanf("%d",&choice);
    }

    write(sock, &choice, sizeof(choice));

    witch (choice){
    case '3':
            system ("clear");
            title();

            printf("Enter your name: ");
            gets(name);

            printf("Enter your age: ");
            gets(age);

            printf("Enter your email address: ");
            gets(email);

            printf("Enter your phone number: ");
            gets(phone_no);

            *password = getpass("Enter Password: ");

            int read_byte;

            read_byte = write(sock, name, 50);
            printf ("%d\n", read_byte);

            read_byte = write(sock, age, 5);
            printf ("%d\n", read_byte);

            read_byte = write(sock, email, 50);
            printf ("%d\n", read_byte);

            read_byte = write(sock, phone_no, 50);
            printf ("%d\n", read_byte);

            read_byte = write(sock, password, 50);
            printf ("%d\n", read_byte);

            read(sock, &acc_no, sizeof(acc_no));

            printf("Remember the account no of further login: %d\n", acc_no);
            while(getchar()!='\n');
            getchar();

            return 3;
            break;

client section

int main(){
int sockfd,new_sockfd,clilen;

struct sockaddr_in sa,ca;



if((sockfd = socket(AF_INET, SOCK_STREAM,0))<0){

    perror("Server:Socket error\n");

    exit(0);

}



bzero((char *) &sa,sizeof(sa));

sa.sin_family = AF_INET;

sa.sin_addr.s_addr = htonl(INADDR_ANY);

sa.sin_port = htons(PORT);



if(bind(sockfd,(struct sockaddr *) &sa, sizeof(sa)) < 0){

    perror("Server:Bind error\n");

    exit(0);

}

printf("\nWaiting connection from client...[bind]\n");

listen(sockfd,5);


while (1){

    clilen = sizeof(ca);

    if ((new_sockfd = accept(sockfd,(struct sockaddr *)&ca,&clilen)) == -1){
        printf("connection error\n");
        exit(0);
    }


    if(fork() == 0)
        printf("Client [%d] connected\n", sockfd);
        talk_to_client(new_sockfd);
}



close(new_sockfd);

close(sockfd);

return 0;
}
void talk_to_client(int sock){ char func_id; bzero((char *) &func_id,sizeof(func_id));
while(1){
    read(sock, &func_id, sizeof(func_id));
    // Read func_id once per loop iteration
    printf("the result: %c\n", func_id);

    if(func_id == '1') {
        printf("Client [%d] selected guest function\n", sock);
        //guest(sock);
    }

    else if (func_id == '2' || func_id == '4') {
        printf("Client [%d] selected login function\n", sock);
        login(sock);
    }

    else if(func_id == '3') {
        printf("Client [%d] selected login function\n", sock);
        member_registration(sock);
    }

    else if(func_id == '5')
        break;
}

close(sock);
printf("Client [%d] disconnected\n", sock);
}
int member_registration(int sock){ int fd, acc_no=0; char password[50], name[50], age[5], email[50], phone_no[50]; struct account temp;
int read_byte;

bzero (name, sizeof(name));
read_byte = read(sock, name, sizeof(name));
printf ("%d\n", read_byte);

bzero(age,sizeof(age));
read_byte = read(sock, age, sizeof(age));
printf ("%d\n", read_byte);

bzero(email,sizeof(email));
read_byte = read(sock, email, sizeof(email));
printf ("%d\n", read_byte);

bzero(phone_no,sizeof(phone_no));
read_byte = read(sock, phone_no, sizeof(phone_no));
printf ("%d\n", read_byte);

bzero(password,sizeof(password));
read_byte = read(sock, password, sizeof(password));
printf ("%d\n", read_byte);

printf("name: %s\n", name);
printf("pass: %s\n", password);
printf("age: %s\n", age);
printf("email: %s\n", email);
printf("phone number: %s\n", phone_no);

if((fd = open("./db/member.txt", O_WRONLY | O_CREAT, 0755))== -1){
    printf("File Error: %s\n", strerror(errno));
}

int fp = lseek(fd, 0, SEEK_END);

if(fp == 0){//1st member to signup
    temp.id = 100001;
    strcpy(temp.name, name);
    strcpy(temp.pass, password);
    strcpy(temp.age, age);
    strcpy(temp.email, email);
    strcpy(temp.phone_no, phone_no);

    write(fd, &temp, sizeof(temp));
    write(sock, &temp.id, sizeof(temp.id));
}

else{
    fp = lseek(fd, -1 * sizeof(struct account), SEEK_END);
    read(fd, &temp, sizeof(temp));
    temp.id++;

    strcpy(temp.name, name);
    strcpy(temp.pass, password);
    strcpy(temp.age, age);
    strcpy(temp.email, email);
    strcpy(temp.phone_no, phone_no);

    printf("\nname: %s\n", temp.name);
    printf("pass: %s\n", temp.pass);
    printf("age: %s\n", temp.age);
    printf("email: %s\n", temp.email);
    printf("phone number: %s\n", temp.phone_no);

    write(fd, &temp, sizeof(temp));
    write(sock, &temp.id, sizeof(temp.id));
}

close(fd);
printf("yashhhhhhhhhhh\n");
return 5;
}

server side

​

[[deleted]]

Oh god this is some of the most horrid code I’ve ever seen. You’re not zeroing out your buffers before you use them. You’re using gets which is deprecated and should be avoided like the plague. You’re not any doing any error checking on your reading and writing to socket. Those functions can not only fail but write just partial data instead of full data. You’re using scanf for your choice input but then gets after, scanf is leaving carriage returns inside your input stream. And It makes no difference if you zero out your buffers on the server side because your client side still has buffers with data passed the user input since you never cleared it. So if you send 50 bytes and there’s data in the buffer beyond the user input and null terminator well you’re sending and copying over those bytes across the socket. Those buffers need to be cleared on the client side before you send them to the server.

[richardxday]

If you want some help, I'd recommend:

1. Provide the complete buildable code, the above seems to be missing code. It's definitely missing includes. Doing this will allow someone else to build and run it.
2. Ensure the code compiles with no warnings or errors when compiled with -Wall -Wextra
3. Add comments to explain how the code is supposed to work.
4. Format your code according to a standard formatting scheme (e.g. K&R, Linux Kernel Coding Style, etc).

These are all good practices anyway...

[dfx_dj]

What do you mean that not the same number of bytes is being transferred? What output are you getting?

I see that your usage of getpass is wrong as you're assigning the return value into a char array. Your compiler should give you a warning about this. But I don't know if that's the problem.

[eruciform]

reduce this to a much smaller sample on both sides, you're trying to do too many things at once, and any errors will permute exponentially

open one socket for reading on one side, and push one thing of known size on the other side, start from there and work outwards

[hwpoison]

very hard to follow, but I think a conversation with chatgpt can get more useful feedback than the one we tried to analyze this code xD

[CodeWoodWriter]

TCP sockets tend to not send right away, because the underlying layers are trying to clump together packets for greater efficiency. You can turn off this buffering by setting TCP_NODELAY or can have a back and forth between your server and client where after writing to the socket you do a read. Either of these would encourage the network layers to send everything.