source: trunk/instant_messenger/socket/server.c @ 151

#include "server.h"

struct accept
{
        int newfd;
        struct sockaddr_in sa;
        struct in_addr jabber_addr;
        unsigned short jabber_port;
};

struct client
{
        char * user;
        int client_fd;
        int jabber_fd;
        int keep_alive;
        time_t last_action;
        struct client * next;
        struct client * previous;
};

struct cat
{
        int in_fd,
                out_fd;
        int jabber,
                keep_alive;
        struct client * client;
};

struct client * clients = (struct client *)NULL;

pthread_mutex_t mutexsum;

int main (int argc, char ** argv)
{
        struct in_addr remote_addr,
                                   local_addr;
        unsigned short remote_port,
                                   local_port;
        int listen_fd;

        ParseArgs (argc, argv, &remote_addr, &remote_port, &local_addr, &local_port);

        Initialise ();

        // Create server socket before becoming a daemon so
        // there is still a chance to print an error message.
        listen_fd = CreateServerSocket (local_addr, local_port);
        if ( listen_fd < 0 )
                pbomb ("Unable to create server socket");

        //Daemonise ();

        MainLoop (listen_fd, remote_addr, remote_port); // never returns

        syslog (LOG_ERR, "fim MainLoop(): %m");
        exit (EXIT_SUCCESS);
}

// ParseArgs()
// Parse the command line arguments to extract the remote
// and local adresses and port numbers, ra, rp, la & lp.
// Exit the program gracefully upon error.
void ParseArgs (int argc, char ** argv, struct in_addr * ra, unsigned short * rp, struct in_addr * la, unsigned short * lp)
{
        // argv[0] = program name
        // argv[1] = remote_addr
        // argv[2] = remote_port
        // argv[3] = local_addr (optional)
        // argv[4] = local_port (optional)

        char * p = strrchr (argv[0], '/');

        strncpy (g_program_name, (p == NULL) ? argv[0] : p + 1, sizeof (g_program_name) - 1);

        if ( (argc < 3) || (argc > 5) )
        {
                fprintf (stderr, "usage: %s remote_addr remote_port [local_addr] [local_port]\n", argv[0]);
                exit (EXIT_FAILURE);
        }

        if ( NameToAddr (argv[1], ra) )
                hbomb ("Unable to resolve \"%s\" to an ip address", argv[1]);

        if ( NameToPort (argv[2], rp, "tcp") )
                quit ("Unable to resolve \"%s\" to a port number", argv[2]);

        if ( argc < 4 )
                la->s_addr = htonl (INADDR_ANY);
        else
                if ( NameToAddr (argv[3], la) )
                        hbomb ("Unable to resolve \"%s\" to an ip address", argv[3]);

        if ( argc < 5 )
                memcpy (lp, rp, sizeof (*lp));
        else
                if ( NameToPort (argv[4], lp, "tcp") )
                        quit ("Unable to resolve \"%s\" to a port number", argv[4]);
}

// Initialise()
// Setup syslog, signal handlers, and other intialisation.
void Initialise (void)
{
        openlog (g_program_name, LOG_PID, LOG_USER);
        syslog (LOG_INFO, "%s started", g_program_name);

        chdir ("/"); // Change working directory to the root.

        umask (0); // Clear our file mode creation mask

        //set_signal_handler (SIGCHLD, sig_child);

        //signal (SIGPIPE, SIG_IGN);
}

// CreateServerSocket()
// Create a socket, bind it to the specified address
// and port, and set it to listen for client connections.
// Returns < 0 on failure to bind, bombs on error otherwise,
// returns the fd of the new socket on success.
int CreateServerSocket (struct in_addr addr, unsigned short port)
{
        int err,
                fd;
        const int on = 1;
        struct sockaddr_in sa;

        // Create a socket and get its descriptor.
        fd = socket (AF_INET, SOCK_STREAM, 0);
        if ( fd < 0 )
                syslog (LOG_ERR, "socket(): %m"), exit (EXIT_FAILURE);

        // Set SO_REUSEADDR socket option
        if ( setsockopt (fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof (on)) < 0 )
                syslog (LOG_ERR, "setsockopt(fd%d, SO_REUSEADDR): %m", fd);

        // Load a sa structure with the specified address and port
        sa.sin_family = AF_INET;
        sa.sin_port = htons (port);
        //sa.sin_addr = addr;
        sa.sin_addr.s_addr = htonl(INADDR_ANY);
        memset (sa.sin_zero, 0, sizeof (sa.sin_zero));

        // Bind our socket to the address and port specified
        err = bind (fd, (struct sockaddr *) &sa, sizeof (sa));
        if ( err < 0 )
        {
                syslog (LOG_ERR, "bind(): %m");
                return err;
        }

        // Tell socket to listen and queue up to 5 incoming connections.
        if ( listen (fd, 5) < 0 )
                syslog (LOG_ERR, "listen(): %m"), exit (EXIT_FAILURE);

        return fd;
}

// MainLoop()
// Classic concurrent server model.
// Wait for a client to connect, fork a child process
// to do the business with the client, parent process
// continues to wait for the next connection.
// This function does not return.
void MainLoop (int listen_fd, struct in_addr rem_addr, unsigned short rem_port)
{
        struct accept * accept;
        pthread_t accept_thread,
                          clear_list_thread;

        pthread_mutex_init(&mutexsum, NULL);

        pthread_create(&clear_list_thread, NULL, (void *) &ClearList, (void *)NULL );

        for ( ; ; )
        {
                accept = AcceptClientConnection (listen_fd);
                accept->jabber_addr = rem_addr;
                accept->jabber_port = rem_port;

                pthread_create(&accept_thread, NULL, (void *) &VerifyClient, (void *) accept);
        }
        pthread_mutex_destroy(&mutexsum);
        pthread_exit(NULL);
}

void ClearList(void)
{
        struct client * current,
                                  * client_remove;

        for ( ; ; )
        {
                current = clients;
                pthread_mutex_lock(&mutexsum);
                while ( current != (struct client *)NULL )
                {
                        //printf("client: %s....\n", current->user);
                        if ( time(NULL) - current->last_action > 60 )
                        {
                                //puts("\t#1 morto!");
                                shutdown(current->jabber_fd, SHUT_RDWR);
                                close(current->jabber_fd);
                                current->jabber_fd = (int)NULL;
                                //if ( current->previous == (struct client *)NULL )
                                //{
                                //puts("\t#2 morto!");
                                        //if ( current->next != (struct client *)NULL )
                                        //      current->next->previous = (struct client *)NULL;
                                        //clients = current->next;
                                //puts("\t#3 morto!");
                                //}
                                /*if ( current->previous != (struct client *)NULL )
                                {
                                        current->previous->next = current->next;
                                        current->next->previous = current->previous;
                                }
                                else
                                {
                                        current->next->previous = (struct client *)NULL;
                                }*/
                                //puts("\t#4 morto!");
                                //client_remove = current;
                                current = current->next;
                                //free(client_remove);
                                //puts("\t#5 morto!");
                        }
                        else
                                current = current->next;
                }
                //puts("-------------------------------");
                pthread_mutex_unlock(&mutexsum);
                sleep(2);
        }
}

// AcceptClientConnection()
// waits for a tcp connect to the socket listen_fd, which
// must already be bound and set to listen on a local port.
// Bombs on error, returns the fd of the new socket on success.
struct accept * AcceptClientConnection (int listen_fd)
{
        int newfd;
        struct sockaddr_in sa;
        socklen_t socklen;

        syslog (LOG_INFO, "AcceptClientConnection(fd%d)", listen_fd);

        // Accept the connection and create a new socket for it.
        socklen = sizeof (sa);
        memset (&sa, 0, socklen);
        do
        {
                newfd = accept (listen_fd, (struct sockaddr *) &sa, &socklen);
        }
        while ( (newfd < 0) && (errno == EINTR) );

        syslog (LOG_INFO, "Accepted client connection on new socket fd%d", newfd);

        if ( newfd < 0 )
                syslog (LOG_ERR, "accept(): %m"), pthread_exit(0);

        if ( socklen != sizeof (sa) )
                syslog (LOG_ERR, "accept() screwed up!"), pthread_exit(0);

        struct accept * new_accept = (struct accept *) malloc(sizeof(struct accept));
        new_accept->newfd = newfd;
        new_accept->sa = sa;

        return (new_accept);
}

void VerifyClient(void * accept)
{
        int jabber_fd = (int)NULL;
        struct accept * client = (struct accept *) accept;
        struct client * user = (struct client *)NULL;
        struct cat * info;
        pthread_t cat_thread;

        unsigned int addr = 0;
        char buf[250];
        addr = ntohl(client->sa.sin_addr.s_addr);
        sprintf(buf,"%d.%d.%d.%d",
                        (addr >> 24)  , (addr >> 16) & 0xFF ,
                        (addr >> 8) & 0xFF ,  addr & 0xFF);
        printf("New connection: %s\n\n", buf);

        if ( strcmp(buf, "10.15.20.42") == 0 || strcmp(buf, "10.15.20.202") == 0 )
        {
                user = Handshake(client->newfd);
                jabber_fd = user->jabber_fd;
        }

        if ( jabber_fd == (int)NULL )
        {
                jabber_fd = ConnectToServer(client->jabber_addr, client->jabber_port);

                if ( user != (struct client *)NULL )
                        user->jabber_fd = jabber_fd;
        }

        info = (struct cat *) malloc(sizeof(struct cat));

        info->out_fd = jabber_fd;
        info->in_fd = client->newfd;
        info->jabber = (int)NULL;
        info->keep_alive = (int)NULL;
        info->client = user;

        pthread_create(&cat_thread, NULL, (void *) &Cat, (void *)info );

        pthread_exit(0);
}

struct client * Handshake(int newfd)
{
        float is_new_client;// = (float) NULL;
        int bytes_rcvd,
                bytes_sent,
                i;

        unsigned char * const buf = (char *) malloc (sizeof(char) * 5);
        char * user = (char *) malloc(128 * sizeof(char)),
                 * pass = (char *) malloc(128 * sizeof(char));

        //struct client * clients = (struct client *)NULL;
        struct client * new_client = (struct client *)NULL;

        bzero(buf, 5);
        sprintf(buf, "user");
        for ( i = 0; i < sizeof(buf); i += bytes_sent )
        {
                bytes_sent = send (newfd, buf + i, sizeof(buf) - i, 0);

                if ( bytes_sent < 0 )
                        break;
        }

        bzero(user, 128);
        if ( (bytes_rcvd = recv (newfd, user, 128, 0)) < 1 )
                pthread_exit(0);

        bzero(buf, 5);
        sprintf(buf, "pass");
        for ( i = 0; i < sizeof(buf); i += bytes_sent )
        {
                bytes_sent = send (newfd, buf + i, sizeof(buf) - i, 0);

                if ( bytes_sent < 0 )
                        break;
        }

        bzero(pass, 128);
        if ( (bytes_rcvd = recv (newfd, pass, 128, 0)) < 1 )
                pthread_exit(0);

        pthread_mutex_lock (&mutexsum);
        if ( clients == (struct client *)NULL )
        {
                clients = (struct client *) malloc(sizeof(struct client));

                new_client = clients;
                new_client->previous = (struct client *)NULL;
                is_new_client = 1;
        }
        else
        {
                new_client = clients;
                while ( ((is_new_client = (float)strcmp(new_client->user, user)) != 0) && (new_client->next != (struct client *)NULL) )
                        new_client = new_client->next;

                if ( is_new_client != 0 )
                {
                        new_client->next = (struct client *) malloc(sizeof(struct client));
                        new_client->next->previous = new_client;
                        new_client = new_client->next;
                }
        }

        if ( is_new_client != 0 )
        {
                new_client->user = user;
                new_client->jabber_fd = (int)NULL;
                new_client->keep_alive = 1;
                new_client->next = (struct client *)NULL;
        }

        bzero(buf, 5);
        if ( is_new_client != 0 || new_client->jabber_fd == (int)NULL  )
                sprintf(buf, "new");
        else
                sprintf(buf, "rec");

        send (newfd, buf, 3, 0);

        new_client->client_fd = newfd;
        new_client->last_action = time(NULL);
        pthread_mutex_unlock(&mutexsum);

        return new_client;
}

// ConnectToServer()
// attempts a tcp connect to the server specified
// by addr and port.  Bombs on failure to connect,
// returns the fd of the new socket on success.
int ConnectToServer (struct in_addr addr, unsigned short port)
{
        // TODO: have a timeout for connect() - see Unix socket FAQ 6.2

        int fd, err;
        struct sockaddr_in sa;

        // Create a socket and get its descriptor.
        fd = socket (AF_INET, SOCK_STREAM, 0);

        if ( fd < 0 )
                syslog (LOG_ERR, "socket(): %m"), pthread_exit(0);//exit (EXIT_FAILURE);

        sa.sin_family = AF_INET;
        sa.sin_port = htons (port);
        sa.sin_addr = addr;
        memset (sa.sin_zero, 0, sizeof (sa.sin_zero));

        err = connect (fd, (struct sockaddr *) &sa, sizeof (sa));
        if (err < 0)
        {
                syslog (LOG_ERR, "Unable to connect socket fd%d to server: %m", fd);
                //exit (EXIT_FAILURE);
                pthread_exit(0);
        }

        syslog (LOG_INFO, "Connected socket fd%d to server", fd);

        return fd;
}

// Cat()
// read data from in_fd and write it to out_fd until
// the connection is closed by one of the peers.
// Data is copied using a dynamically allocated buffer.
//void Cat (int in_fd, int out_fd)
//void Cat (int in_fd, int out_fd)
void Cat (void * info)
{
        unsigned char * const buf_in = (char *) malloc (sizeof(char) * BUF_SIZE);
        unsigned char * const buf_out = (char *) malloc (sizeof(char) * BUF_SIZE);
        int bytes_rcvd_in = (int) NULL,
                bytes_sent_in = (int) NULL,
                bytes_rcvd_out = (int) NULL,
                bytes_sent_out = (int) NULL,
                i,
                in_fd,
                out_fd;
        struct cat * user = (struct cat *) info;
        in_fd = user->in_fd;
        out_fd = user->out_fd;

        syslog (LOG_INFO, "Cat(fd%d, fd%d)", in_fd, out_fd);

        if ( buf_in == NULL || buf_out == NULL )
                syslog (LOG_ERR, "malloc(): %m"), pthread_exit(0);

        fcntl(in_fd, F_SETFL, fcntl(in_fd, F_GETFL, 0) | O_NDELAY);
        fcntl(out_fd, F_SETFL, fcntl(out_fd, F_GETFL, 0) | O_NDELAY);

        bzero(buf_in, BUF_SIZE);
        bzero(buf_out, BUF_SIZE);
        do
        {
                bzero(buf_in, BUF_SIZE);
                if ( (bytes_rcvd_in = recv (in_fd, buf_in, BUF_SIZE, 0)) != 0 && strlen(buf_out) > 0 )
                {
                        for ( i = 0; i < bytes_rcvd_out; i += bytes_sent_in )
                        {
                                bytes_sent_in = send (in_fd, buf_out + i, bytes_rcvd_out - i, 0);

                                if ( bytes_sent_in < 0 )
                                        break;
                        }
                }

                bzero(buf_out, BUF_SIZE);
                if ( (bytes_rcvd_out = recv (out_fd, buf_out, BUF_SIZE, 0)) != 0 && strlen(buf_in) > 0 )
                {
                        //printf("\n%s\n", buf_in);
                        for ( i = 0; i < bytes_rcvd_in; i += bytes_sent_out )
                        {
                                bytes_sent_out = send (out_fd, buf_in + i, bytes_rcvd_in - i, 0);

                                if ( bytes_sent_out < 0 )
                                        break;
                        }
                }
                usleep(500);
                //sleep(1);
                //printf("bytes_rcvd_in: %d\nbytes_rcvd_out: %d\n\n", bytes_rcvd_in, bytes_rcvd_out);
        }
        while ( (bytes_rcvd_in != 0) && (bytes_rcvd_out != 0) );

        //puts("FIM CAT");

        /*
        if ( ((bytes_rcvd_in < 0) || (bytes_rcvd_out < 0)) && (errno != ECONNRESET) )
                syslog (LOG_ERR, "recv(): %m"), pthread_exit(0);

        if ( ((bytes_sent_in < 0) || (bytes_sent_out < 0)) && (errno != EPIPE) )
                syslog (LOG_ERR, "send(): %m"), pthread_exit(0);
        */

        if ( user->jabber && !user->keep_alive )
        {
                shutdown(user->jabber, SHUT_RDWR);
                close(user->jabber);
        }
        //puts("shutdown");
        shutdown(user->in_fd, SHUT_RDWR);
        //puts("close");
        close(user->in_fd);
        free (buf_in);
        //free (buf_out);
        pthread_exit(0);
}

// NameToAddress()
// Convert name to an ip address.
// Returns 0 on success, -1 on failure.
int NameToAddr (const char * name, struct in_addr * p_inaddr)
{
        struct hostent * he;

        // First, attempt to convert from string ip format
        // TODO: use inet_aton() instead
        p_inaddr->s_addr = inet_addr (name);
        if ( p_inaddr->s_addr != -1U ) // Success
                return 0;

        // Next, attempt to read from /etc/hosts or do a DNS lookup
        he = gethostbyname (name);
        if ( he != NULL ) // Success
        {
                memcpy (p_inaddr, he->h_addr, sizeof (struct in_addr));
                return 0;
        }

        return -1; // Failed to resolve name to an ip address
}

// NameToPort()
// Convert name to a port number. Name can either be a port name
// (in which case proto must also be set to either "tcp" or "udp")
// or name can be the ascii representation of the port number.
// Returns 0 on success, -1 on failure.
int NameToPort (const char * name, unsigned short * port, const char * proto)
{
        unsigned long lport;
        char * errpos;
        struct servent * se;

        // First, attempt to convert string to integer
        lport = strtoul (name, &errpos, 0);
        if ( (*errpos == 0) && (lport <= 65535) ) // Success
        {
                *port = lport;
                return 0;
        }

        // Next, attempt to read the string from /etc/services
        se = getservbyname (name, proto);
        if ( se != NULL) // Success
        {
                *port = ntohs (se->s_port);
                return 0;
        }

        return -1; // Failed to resolve port name to a number
}

// quit()
// Print an error message to stderr
// and syslog, then exit the program.
void quit (const char * fmt, ...) // quit with msg
{
        va_list ap;

        fflush (stdout);

        fprintf (stderr, "%s: ", g_program_name);

        va_start (ap, fmt);
        vfprintf (stderr, fmt, ap);
        va_end (ap);

        fputc ('\n', stderr);

        syslog (LOG_ERR, "I quit!");

        exit (EXIT_FAILURE);
}

// pbomb()
// Print an error message to stderr
// and syslog, then exit the program.
// pbomb() additionally include the
// string representation of errno.
void pbomb (const char * fmt, ...) // bomb with perror
{
        va_list ap;
        int errno_save = errno;
        char buf[100];

        fflush (stdout);

        fprintf (stderr, "%s: ", g_program_name);

        va_start (ap, fmt);
        vsnprintf (buf, sizeof (buf), fmt, ap);
        va_end (ap);

        errno = errno_save;
        perror (buf);

        syslog (LOG_ERR, "Bang!: %s: %m", buf);

        exit (EXIT_FAILURE);
}

// hbomb()
// Print an error message to stderr
// and syslog, then exit the program.
// hbomb() additionally include the
// string representation of h_errno.
void hbomb (const char * fmt, ...) // bomb with herror
{
        va_list ap;
        int h_errno_save = h_errno;
        char buf[100];

        fflush (stdout);

        fprintf (stderr, "%s: ", g_program_name);

        va_start (ap, fmt);
        vsnprintf (buf, sizeof (buf), fmt, ap);
        va_end (ap);

        h_errno = h_errno_save;
        herror (buf);

        syslog (LOG_ERR, "Bang!: %s: %s", buf, hstrerror (h_errno));

        exit (EXIT_FAILURE);
}

// set_signal_handler()
// Sets a signal handler function.
// Similar to signal() but this method
// is more portable between platforms.
void set_signal_handler (int signum, signal_handler_t sa_handler_func)
{
        struct sigaction act;

        act.sa_handler = sa_handler_func;
        sigemptyset (&(act.sa_mask));
        act.sa_flags = 0;

        if ( sigaction (signum, &act, NULL) < 0 )
        {
                syslog (LOG_ERR, "Error setting handler for signal %d: %m", signum);
                exit (EXIT_FAILURE);
        }
}