error connecting with sockets

[ltcabral]

Hello,
i made client and server applications, using sockets, to connect to each other in same machine. It works in my unversity but when i use them at home it doesnt work.

I open the server app and it waits for client to connect, when i open client, server exits with error message. The error is in the function accept()... and its something like "Invalid Argument".

I dont have router or firewall... using ubuntu 7.10... is this related to my operational system blocking the connection? or i can fix it in my program?

Here is the code for server/client

./server
./client localhost

#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#define SERVER_PORT 5432
#define MAX_PENDING 5
#define MAX_LINE 256

int main() {
    struct sockaddr_in sin;
    char buf[MAX_LINE];
    int len;
    int s, new_s;
    /* build address data structure */
    bzero((char *)&sin, sizeof(sin));
    sin.sin_family = AF_INET;
    sin.sin_addr.s_addr = INADDR_ANY;
    sin.sin_port = htons(SERVER_PORT);

    /* setup passive open */
    if ((s = socket(PF_INET, SOCK_STREAM, 0)) < 0) {
        perror("simplex-talk: socket");
        exit(1);
    }
    if ((bind(s, (struct sockaddr *)&sin, sizeof(sin))) < 0) {
        perror("simplex-talk: bind");
        exit(1);
    }
    listen(s, MAX_PENDING);

    /* wait for connection, then receive and print text */
    while(1) {
        if ((new_s = accept(s, (struct sockaddr *)&sin, &len)) < 0){
            perror("simplex-talk: accept");
            exit(1);
        }
        while (len = recv(new_s, buf, sizeof(buf), 0))
            fputs(buf, stdout);

        close(new_s);
    }
}

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

#define SERVER_PORT 5432
#define MAX_LINE 256

int main(int argc, char * argv[]) {
    FILE *fp;
    struct hostent *hp;
    struct sockaddr_in sin;
    char *host;
    char buf[MAX_LINE];
    int s;
    int len;

    if (argc==2) {
        host = argv[1];
    }
    else {
        fprintf(stderr, "usage: simplex-talk host\n");
        exit(1);
    }
    /* translate host name into peer's IP address */
    hp = gethostbyname(host);
    if (!hp) {
        fprintf(stderr, "simplex-talk: unknown host: &#37;s\n", host);
        exit(1);
    }
    /* build address data structure */
    bzero((char *)&sin, sizeof(sin));
    sin.sin_family = AF_INET;
    bcopy(hp->h_addr, (char *)&sin.sin_addr, hp->h_length);
    sin.sin_port = htons(SERVER_PORT);
    /* active open */
    if ((s = socket(PF_INET, SOCK_STREAM, 0)) < 0) {
        perror("simplex-talk: socket");
        exit(1);
    }
    if (connect(s, (struct sockaddr *)&sin, sizeof(sin)) < 0) {
        perror("simplex-talk: connect");
        close(s);
        exit(1);
    }
    /* main loop: get and send lines of text */
    while (fgets(buf, sizeof(buf), stdin)) {
        buf[MAX_LINE-1] = '\0';
        len = strlen(buf) + 1;
        send(s, buf, len, 0);
    }
}

[rags_to_riches]

Where do you set the len argument you're passing to accept?

[ltcabral]

hm... accept will write in the variable len so i only need to declare it an int... right?

[rags_to_riches]

From here:

The addrlen argument is a value-result argument: it should initially contain the size of the structure pointed to by addr; on return it will contain the actual length (in bytes) of the address returned.