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server.c
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server.c
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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <netdb.h>
#include <sys/socket.h>
#include <unistd.h>
#include <pthread.h>
#include <ctype.h>
#include <semaphore.h>
#include "chat.h"
int num_users, max_users = 10;
int* clientfds;
char** usernames;
sem_t mutex;
void* user_thread(void*);
int clean_username(char*);
struct user_data {
int clientfd;
char username[MAX_USERNAME_LENGTH];
int user_pos;
};
int main() {
int status, serverfd, clientfd, bytesrecv;
char active;
char username[MAX_USERNAME_LENGTH];
struct addrinfo hints, * res, * p;
struct sockaddr_storage clientaddrs;
socklen_t sin_size;
struct user_data data;
pthread_t tid;
// Initialize server
memset(&hints, 0, sizeof hints);
hints.ai_flags = AI_PASSIVE;
hints.ai_family = AF_UNSPEC;
hints.ai_socktype = SOCK_STREAM;
if ((status = getaddrinfo(NULL, SERVER_PORT, &hints, &res)) != 0) {
fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(status));
return 1;
}
for (p = res; p != NULL; p = p->ai_next) {
if ((serverfd = socket(p->ai_family, p->ai_socktype, p->ai_protocol)) == -1) {
continue;
}
// Force on SERVER_PORT
int yes = 1;
if (setsockopt(serverfd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(int)) == -1) {
perror("setsockopt");
return 1;
}
if ((bind(serverfd, p->ai_addr, p->ai_addrlen)) == -1) {
close(serverfd);
continue;
}
break;
}
if (p == NULL) {
fprintf(stderr, "SERVER: Failed to bind\n");
return 1;
}
// Allocate usernames array
usernames = (char**)malloc(max_users * sizeof(char*));
for (int i = 0; i < max_users; i++) {
usernames[i] = (char*)malloc(MAX_USERNAME_LENGTH * sizeof(char));
}
num_users = 0;
active = 1;
// Allocate clientfds array
clientfds = (int*)malloc(max_users * sizeof(int));
if (clientfds == NULL) {
fprintf(stderr, "SERVER: Memory allocation error\n");
return 1;
}
// Listen for client connections
if ((listen(serverfd, max_users)) == -1) {
perror("SERVER: listen");
return 1;
}
while (active) {
// Accept client connection
if ((clientfd = (accept(serverfd, (struct sockaddr*)&clientaddrs, &sin_size))) == -1) {
perror("SERVER: accept");
break;
}
// Get username from client
if ((bytesrecv = recv(clientfd, username, sizeof username, 0)) == -1) {
perror("SERVER: recv");
return 1;
}
username[bytesrecv] = 0;
// Check username
int err = 0;
// Check if legal format
if (clean_username(username) == -1) {
err = -1;
}
// Check for duplicates
else if (num_users > 0) {
for (int i = 0; i < num_users; i++) {
if (strcmp(username, usernames[i]) == 0) {
err = -2;
break;
}
}
}
if ((send(clientfd, &err, sizeof err, 0)) == -1) {
perror("SERVER: send");
break;
}
if (err == 0) {
if (num_users + 1 > max_users) {
int new_size = max_users + 10;
// Resize clientfds
clientfds = realloc(clientfds, new_size * sizeof(int));
// Resize usernames
usernames = realloc(usernames, new_size * sizeof(char*));
for (int i = num_users; i < new_size; i++) {
usernames[i] = (char*)malloc(MAX_USERNAME_LENGTH * sizeof(char));
}
}
strcpy(usernames[num_users], username); // Save username
// Send success message to client
char* msg = "Connected to server.";
if ((send(clientfd, msg, strlen(msg), 0)) == -1) {
perror("SERVER: send");
break;
}
// Create thread for client
strcpy(data.username, username);
data.clientfd = clientfd;
data.user_pos = num_users;
if ((pthread_create(&tid, NULL, user_thread, &data)) != 0) {
fprintf(stderr, "SERVER: Failed to create thread\n");
return 1;
}
clientfds[num_users] = clientfd;
num_users++;
printf("%s connected.\n", username);
}
}
close(serverfd);
}
void* user_thread(void* arg) {
struct user_data data = *(struct user_data*)arg;
char msg[MAX_MESSAGE_LENGTH];
char sendmsg[MAX_MESSAGE_LENGTH + MAX_USERNAME_LENGTH + 2];
int bytesrecv;
while (1) {
// Receive messages
if ((bytesrecv = recv(data.clientfd, msg, sizeof msg, 0)) == -1) {
perror("SERVER: send");
break;
}
else if (bytesrecv == 0) {
printf("Client disconnected.\n");
// Free up username
strcpy(usernames[data.user_pos], "?");
break;
}
msg[bytesrecv] = 0;
// Send messages to all connected clients
sprintf(sendmsg, "%s: %s", data.username, msg);
printf("%s\n", sendmsg);
for (int i = 0; i < num_users; i++) {
if (clientfds[i] != data.clientfd && (send(clientfds[i], sendmsg, strlen(sendmsg), 0) == -1)) {
perror("SERVER: send");
}
}
}
return NULL;
}
int clean_username(char* username) {
while (*username) {
if (*username >= 48 && *username <= 57 // 0-9
|| *username >= 65 && *username <= 90 // A-Z
|| *username >= 97 && *username <= 122 // a-z
|| *username == 95) { // _
*username = tolower((unsigned char)*username);
username++;
}
else {
return -1;
}
}
return 0;
}