主頁 > 後端開發 > 將檔案從客戶端發送到服務器，然后使用C中的套接字在另一個客戶端中讀取檔案

將檔案從客戶端發送到服務器，然后使用C中的套接字在另一個客戶端中讀取檔案

2022-04-24 01:52:34 後端開發

應用程式中有兩個客戶端和一個服務器。兩個客戶端通過服務器相互通信。當一個客戶端向服務器發送訊息時，服務器將訊息作為文本檔案存盤在服務器中，檔案名為clientid_timestamp.txt。然后服務器將檔案發送到讀取檔案并在其終端上顯示其內容的另一個客戶端。

我已經為下面給出的客戶端和服務器撰寫了代碼。我面臨的問題是客戶端無法從服務器獲取檔案列印它的內容。它沒有在終端中顯示輸出。

終端中的服務器端影像

終端中的客戶端影像

服務器代碼：

#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <pthread.h>
#include <sys/types.h>
#include <signal.h>

#define MAX_CLIENTS 3
#define BUFFER_SZ 2048
#define SIZE 1024

static _Atomic unsigned int cli_count = 0;
static int uid = 10;

/* Client structure */
typedef struct{
    struct sockaddr_in address;
    int sockfd;
    int uid;
    char name[32];
} client_t;

client_t *clients[MAX_CLIENTS];

pthread_mutex_t clients_mutex = PTHREAD_MUTEX_INITIALIZER;

void str_overwrite_stdout() {
    printf("\r%s", "> ");
    fflush(stdout);
}

void print_client_addr(struct sockaddr_in addr){
    printf("%d.%d.%d.%d",
        addr.sin_addr.s_addr & 0xff,
        (addr.sin_addr.s_addr & 0xff00) >> 8,
        (addr.sin_addr.s_addr & 0xff0000) >> 16,
        (addr.sin_addr.s_addr & 0xff000000) >> 24);
}

/* Add clients to queue */
void queue_add(client_t *cl){
    pthread_mutex_lock(&clients_mutex);

    for(int i=0; i < MAX_CLIENTS;   i){
        if(!clients[i]){
            clients[i] = cl;
            break;
        }
    }

    pthread_mutex_unlock(&clients_mutex);
}

/* Remove clients to queue */
void queue_remove(int uid){
    pthread_mutex_lock(&clients_mutex);

    for(int i=0; i < MAX_CLIENTS;   i){
        if(clients[i]){
            if(clients[i]->uid == uid){
                clients[i] = NULL;
                break;
            }
        }
    }

    pthread_mutex_unlock(&clients_mutex);
}


void send_file(int sockfd){
    int n;
    char data[SIZE] = {0};

    FILE *fp = fopen("clientid_timestamp.txt", "r");
    if (fp == NULL){
        printf("Error opening file!\n");
        exit(1);
    
    }

    while(fgets(data, SIZE, fp) != NULL) {
        if (send(sockfd, data, sizeof(data), 0) == -1) {
        perror("[-]Error in sending file.");
        exit(1);
        }
        printf("hello");
        bzero(data, SIZE);
    }

}

/* Send message to all clients except sender */
void send_message(char *s, int uid){
    pthread_mutex_lock(&clients_mutex);

    for(int i=0; i<MAX_CLIENTS;   i){
        if(clients[i]){
            if(clients[i]->uid != uid){
                printf("MESSAGE SENT TO %s:%d \n",inet_ntoa(clients[i]->address.sin_addr),ntohs(clients[i]->address.sin_port));
                send_file(clients[i]->uid);
            }
        }
    }

    pthread_mutex_unlock(&clients_mutex);
}

/* Handle all communication with the client */
void *handle_client(void *arg){

    char buff_out[BUFFER_SZ];
    char name[32];
    int leave_flag = 0;

    cli_count  ;
    client_t *cli = (client_t *)arg;

    
    
    // Name

    bzero(buff_out, BUFFER_SZ);

    while(1){
        if (leave_flag) {
            break;
        }

        int receive = recv(cli->sockfd, buff_out, BUFFER_SZ, 0);
        if (receive > 0){
            if(strlen(buff_out) > 0){

                FILE *f = fopen("clientid_timestamp.txt", "w");
                if (f == NULL){
                    printf("Error opening file!\n");
                    exit(1);
                }

                /* print some text */
                fprintf(f, "%s", buff_out);
                send_message(buff_out, cli->uid);
                fclose(f);
                printf("\n");
            } 
        } 
        else {
            printf("ERROR: -1\n");
            leave_flag = 1;
        }

        bzero(buff_out, BUFFER_SZ);
    }

  /* Delete client from queue and yield thread */
    close(cli->sockfd);
    queue_remove(cli->uid);
    free(cli);
    cli_count--;
    pthread_detach(pthread_self());
    return NULL;
}

int main(int argc, char **argv){
    if(argc != 2){
        printf("Usage: %s <port>\n", argv[0]);
        return EXIT_FAILURE;
    }

    char *ip = "127.0.0.1";
    int port = atoi(argv[1]);
    int option = 1;
    int listenfd = 0, connfd = 0;
  struct sockaddr_in serv_addr;
  struct sockaddr_in cli_addr;
  pthread_t tid;

  /* Socket settings */
  listenfd = socket(AF_INET, SOCK_STREAM, 0);
  serv_addr.sin_family = AF_INET;
  serv_addr.sin_addr.s_addr = inet_addr(ip);
  serv_addr.sin_port = htons(port);

  /* Ignore pipe signals */
    signal(SIGPIPE, SIG_IGN);

    if(setsockopt(listenfd, SOL_SOCKET,(SO_REUSEPORT | SO_REUSEADDR),(char*)&option,sizeof(option)) < 0){
        perror("ERROR: setsockopt failed");
    return EXIT_FAILURE;
    }

    /* Bind */
  if(bind(listenfd, (struct sockaddr*)&serv_addr, sizeof(serv_addr)) < 0) {
    perror("ERROR: Socket binding failed");
    return EXIT_FAILURE;
  }

  /* Listen */
  if (listen(listenfd, 10) < 0) {
    perror("ERROR: Socket listening failed");
    return EXIT_FAILURE;
    }

    printf("=== WELCOME TO THE CHATROOM ===\n");

    char exit[] = "exit_client";
    char accepted[] = "accept_client";

    while(1){
        socklen_t clilen = sizeof(cli_addr);
        connfd = accept(listenfd, (struct sockaddr*)&cli_addr, &clilen);

        /* Check if max clients is reached */
        if((cli_count) == MAX_CLIENTS){
            printf("Max clients reached. Rejected: ");
            print_client_addr(cli_addr);
            printf(":%d\n", cli_addr.sin_port);
            send(connfd, exit, strlen(exit), 0);
            close(connfd);
            continue;
        }
        else{
            
            send(connfd, accepted, strlen(accepted), 0);
            client_t *cli = (client_t *)malloc(sizeof(client_t));
            cli->address = cli_addr;
            cli->sockfd = connfd;
            cli->uid = uid  ;

            printf("Client Connected : ");
            printf("%s:%d \n",inet_ntoa(cli->address.sin_addr),ntohs(cli->address.sin_port));
            
            /* Add client to the queue and fork thread */
            queue_add(cli);
            pthread_create(&tid, NULL, &handle_client, (void*)cli);

            /* Reduce CPU usage */
            sleep(1);
        }

        /* Client settings */
        
    }

    return EXIT_SUCCESS;
}

客戶代碼：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <signal.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <pthread.h>

#define LENGTH 2048
#define MAX 10000 
// Global variables
volatile sig_atomic_t flag = 0;
int sockfd = 0;
char name[32];

void str_overwrite_stdout() {
  printf("%s", "> ");
  fflush(stdout);
}

void str_trim_lf (char* arr, int length) {
  int i;
  for (i = 0; i < length; i  ) { // trim \n
    if (arr[i] == '\n') {
      arr[i] = '\0';
      break;
    }
  }
}

void catch_ctrl_c_and_exit(int sig) {
    flag = 1;
}

void send_msg_handler() {
  char message[LENGTH] = {};
    char buffer[LENGTH   32] = {};

  while(1) {
    str_overwrite_stdout();
    fgets(message, LENGTH, stdin);
    //str_trim_lf(message, LENGTH);

    if (strcmp(message, "exit") == 0) {
            break;
    } else {
      sprintf(buffer, "%s\n", message);
      send(sockfd, buffer, strlen(buffer), 0);
    }

        bzero(message, LENGTH);
    bzero(buffer, LENGTH   32);
  }
  catch_ctrl_c_and_exit(2);
}

void recv_msg_handler() {
    

    while (1) {

      int n;
      FILE *fp;
      char buff[1024]="",*ptr=buff;
      int bytes=0,bytes_received;
      while(bytes_received = recv(sockfd,ptr, 1, 0)){

        printf("%s\n",ptr);
        if(bytes_received==-1){
          perror("recieve");
          exit(3);
        }

        if(*ptr=='\n' ) break;
          ptr  ; //each times we increment it it points to the buffer element
      }

      *ptr=0;
      ptr=buff;
      printf("%s\n",ptr);
      str_overwrite_stdout();
    }         
}



int main(int argc, char **argv){
    if(argc != 2){
        printf("Usage: %s <port>\n", argv[0]);
        return EXIT_FAILURE;
    }

    char *ip = "127.0.0.1";
    int port = atoi(argv[1]);

    signal(SIGINT, catch_ctrl_c_and_exit);



    struct sockaddr_in server_addr;

    /* Socket settings */
    sockfd = socket(AF_INET, SOCK_STREAM, 0);
  server_addr.sin_family = AF_INET;
  server_addr.sin_addr.s_addr = inet_addr(ip);
  server_addr.sin_port = htons(port);


  // Connect to Server
  int err = connect(sockfd, (struct sockaddr *)&server_addr, sizeof(server_addr));
  if (err == -1) {
        printf("ERROR: connect\n");
        return EXIT_FAILURE;
    }

  char exit_client[] = "exit_client";
  char buff[MAX];
    bzero(buff, sizeof(buff));
  recv(sockfd, buff, 1024, 0);
  if((strcmp(buff, exit_client) == 0)){
    printf("limit exceeded , closing the client \n");
        close(sockfd);
    return EXIT_SUCCESS;
    }

  else{
    printf("client accepted by the server and limit not exceeded \n");
    }
  
    printf("=== WELCOME TO THE CHATROOM ===\n");

    pthread_t send_msg_thread;
  if(pthread_create(&send_msg_thread, NULL, (void *) send_msg_handler, NULL) != 0){
        printf("ERROR: pthread\n");
    return EXIT_FAILURE;
    }

    pthread_t recv_msg_thread;
  if(pthread_create(&recv_msg_thread, NULL, (void *) recv_msg_handler, NULL) != 0){
        printf("ERROR: pthread\n");
        return EXIT_FAILURE;
    }

    while (1){
        if(flag){
            printf("\nBye\n");
            break;
    }
    }

    close(sockfd);

    return EXIT_SUCCESS;
}

編輯-1

我已經做出了用戶 stackinside 建議的更改，并且代碼現在可以作業，但是在過去的幾個小時里我一直面臨一個新問題，我無法理解它的原因是什么。

現在出現的問題是客戶端只能向其他客戶端發送一次訊息，反之亦然，然后除了新行之外，它無法再發送任何訊息。更新的代碼基于我所做的更改

終端中的客戶端影像

終端中的服務器端影像

服務器代碼：

#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <pthread.h>
#include <sys/types.h>
#include <signal.h>

#define MAX_CLIENTS 3
#define BUFFER_SZ 2048
#define SIZE 1024

static _Atomic unsigned int cli_count = 0;
static int uid = 10;

/* Client structure */
typedef struct{
    struct sockaddr_in address;
    int sockfd;
    int uid;
    char name[32];
} client_t;

client_t *clients[MAX_CLIENTS];

void str_trim_lf (char* arr, int length) {
  int i;
  for (i = 0; i < length; i  ) { // trim \n
    if (arr[i] == '\n') {
      arr[i] = '\0';
      break;
    }
  }
}

pthread_mutex_t clients_mutex = PTHREAD_MUTEX_INITIALIZER;

void str_overwrite_stdout() {
    printf("\r%s", "> ");
    fflush(stdout);
}

void print_client_addr(struct sockaddr_in addr){
    printf("%d.%d.%d.%d",
        addr.sin_addr.s_addr & 0xff,
        (addr.sin_addr.s_addr & 0xff00) >> 8,
        (addr.sin_addr.s_addr & 0xff0000) >> 16,
        (addr.sin_addr.s_addr & 0xff000000) >> 24);
}

/* Add clients to queue */
void queue_add(client_t *cl){
    pthread_mutex_lock(&clients_mutex);

    for(int i=0; i < MAX_CLIENTS;   i){
        if(!clients[i]){
            clients[i] = cl;
            break;
        }
    }

    pthread_mutex_unlock(&clients_mutex);
}

/* Remove clients to queue */
void queue_remove(int uid){
    pthread_mutex_lock(&clients_mutex);

    for(int i=0; i < MAX_CLIENTS;   i){
        if(clients[i]){
            if(clients[i]->uid == uid){
                clients[i] = NULL;
                break;
            }
        }
    }

    pthread_mutex_unlock(&clients_mutex);
}


void send_file(int sockfd){
    int n;
    char data[SIZE] = {0};

    FILE *fp = fopen("clientid_timestamp.txt", "r");
    if (fp == NULL){
        printf("Error opening file!\n");
        exit(1);
    
    }

    while(fgets(data, SIZE, fp) != NULL) {
        if (send(sockfd, data, sizeof(data), 0) == -1) {
        perror("[-]Error in sending file.");
        exit(1);
        }
        bzero(data, SIZE);
    }
}

/* Send message to all clients except sender */
void send_message(char *s, int uid){
    pthread_mutex_lock(&clients_mutex);

    for(int i=0; i<MAX_CLIENTS;   i){
        if(clients[i]){
            if(clients[i]->uid != uid){
                printf("MESSAGE SENT TO %s:%d \n",inet_ntoa(clients[i]->address.sin_addr),ntohs(clients[i]->address.sin_port));
                send_file(clients[i]->sockfd);
            }
        }
    }

    pthread_mutex_unlock(&clients_mutex);
}

/* Handle all communication with the client */
void *handle_client(void *arg){

    char buff_out[BUFFER_SZ];
    char name[32];
    int leave_flag = 0;

    cli_count  ;
    client_t *cli = (client_t *)arg;

    
    
    // Name

    bzero(buff_out, BUFFER_SZ);

    while(1){
        if (leave_flag) {
            break;
        }

        int receive = recv(cli->sockfd, buff_out, BUFFER_SZ, 0);
        if (receive > 0){
            if(strlen(buff_out) > 0){

                FILE *f = fopen("clientid_timestamp.txt", "w");
                if (f == NULL){
                    printf("Error opening file!\n");
                    exit(1);
                }

                /* print some text */
                fprintf(f, "%s", buff_out);
                fclose(f);
                send_message(buff_out, cli->uid);
                printf("\n");
            } 
        } 
        else {
            printf("ERROR: -1\n");
            leave_flag = 1;
        }

        bzero(buff_out, BUFFER_SZ);
    }

  /* Delete client from queue and yield thread */
    close(cli->sockfd);
    queue_remove(cli->uid);
    free(cli);
    cli_count--;
    pthread_detach(pthread_self());
    return NULL;
}

int main(int argc, char **argv){
    if(argc != 2){
        printf("Usage: %s <port>\n", argv[0]);
        return EXIT_FAILURE;
    }

    char *ip = "127.0.0.1";
    int port = atoi(argv[1]);
    int option = 1;
    int listenfd = 0, connfd = 0;
  struct sockaddr_in serv_addr;
  struct sockaddr_in cli_addr;
  pthread_t tid;

  /* Socket settings */
  listenfd = socket(AF_INET, SOCK_STREAM, 0);
  serv_addr.sin_family = AF_INET;
  serv_addr.sin_addr.s_addr = inet_addr(ip);
  serv_addr.sin_port = htons(port);

  /* Ignore pipe signals */
    signal(SIGPIPE, SIG_IGN);

    if(setsockopt(listenfd, SOL_SOCKET,(SO_REUSEPORT | SO_REUSEADDR),(char*)&option,sizeof(option)) < 0){
        perror("ERROR: setsockopt failed");
    return EXIT_FAILURE;
    }

    /* Bind */
  if(bind(listenfd, (struct sockaddr*)&serv_addr, sizeof(serv_addr)) < 0) {
    perror("ERROR: Socket binding failed");
    return EXIT_FAILURE;
  }

  /* Listen */
  if (listen(listenfd, 10) < 0) {
    perror("ERROR: Socket listening failed");
    return EXIT_FAILURE;
    }

    printf("=== WELCOME TO THE CHATROOM ===\n");

    char exit[] = "exit_client";
    char accepted[] = "accept_client";

    while(1){
        socklen_t clilen = sizeof(cli_addr);
        connfd = accept(listenfd, (struct sockaddr*)&cli_addr, &clilen);

        /* Check if max clients is reached */
        if((cli_count) == MAX_CLIENTS){
            printf("Max clients reached. Rejected: ");
            print_client_addr(cli_addr);
            printf(":%d\n", cli_addr.sin_port);
            send(connfd, exit, strlen(exit), 0);
            close(connfd);
            continue;
        }
        else{
            
            send(connfd, accepted, strlen(accepted), 0);
            client_t *cli = (client_t *)malloc(sizeof(client_t));
            cli->address = cli_addr;
            cli->sockfd = connfd;
            cli->uid = uid  ;

            printf("Client Connected : ");
            printf("%s:%d \n",inet_ntoa(cli->address.sin_addr),ntohs(cli->address.sin_port));
            
            /* Add client to the queue and fork thread */
            queue_add(cli);
            pthread_create(&tid, NULL, &handle_client, (void*)cli);

            /* Reduce CPU usage */
            sleep(1);
        }

        /* Client settings */
        
    }

    return EXIT_SUCCESS;
}

客戶端代碼：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <signal.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <pthread.h>

#define LENGTH 2048
#define MAX 10000 
// Global variables
volatile sig_atomic_t flag = 0;
int sockfd = 0;
char name[32];

void str_overwrite_stdout() {
  printf("%s", "> ");
  fflush(stdout);
}

void str_trim_lf (char* arr, int length) {
  int i;
  for (i = 0; i < length; i  ) { // trim \n
    if (arr[i] == '\n') {
      arr[i] = '\0';
      break;
    }
  }
}

void catch_ctrl_c_and_exit(int sig) {
    flag = 1;
}

void send_msg_handler() {
  char message[LENGTH] = {};
    char buffer[LENGTH   32] = {};

  while(1) {
    str_overwrite_stdout();
    fgets(message, LENGTH, stdin);
    str_trim_lf(message, LENGTH);

    if (strcmp(message, "exit") == 0) {
            break;
    } else {
      sprintf(buffer, "%s\n", message);
      send(sockfd, buffer, strlen(buffer), 0);
    }

        bzero(message, LENGTH);
    bzero(buffer, LENGTH   32);
  }
  catch_ctrl_c_and_exit(2);
}

void recv_msg_handler() {

    int n;
    FILE *fp;
    char buff[1024]="",*ptr=buff;
    int bytes=0,bytes_received;
  
    while (1) {

      
      while(bytes_received = recv(sockfd,ptr, 1, 0)){

        if(bytes_received==-1){
          perror("recieve");
          exit(3);
        }

        if(*ptr=='\n' ) break;
          ptr  ; //each times we increment it it points to the buffer element
      }
      *ptr=0;
      str_trim_lf(buff, strlen(buff));
      ptr=buff;
      printf("%s \n",ptr);
      str_overwrite_stdout();
    }         
}



int main(int argc, char **argv){
    if(argc != 2){
        printf("Usage: %s <port>\n", argv[0]);
        return EXIT_FAILURE;
    }

    char *ip = "127.0.0.1";
    int port = atoi(argv[1]);

    signal(SIGINT, catch_ctrl_c_and_exit);



    struct sockaddr_in server_addr;

    /* Socket settings */
    sockfd = socket(AF_INET, SOCK_STREAM, 0);
  server_addr.sin_family = AF_INET;
  server_addr.sin_addr.s_addr = inet_addr(ip);
  server_addr.sin_port = htons(port);


  // Connect to Server
  int err = connect(sockfd, (struct sockaddr *)&server_addr, sizeof(server_addr));
  if (err == -1) {
        printf("ERROR: connect\n");
        return EXIT_FAILURE;
    }

  char exit_client[] = "exit_client";
  char buff[MAX];
    bzero(buff, sizeof(buff));
  recv(sockfd, buff, 1024, 0);
  if((strcmp(buff, exit_client) == 0)){
    printf("limit exceeded , closing the client \n");
        close(sockfd);
    return EXIT_SUCCESS;
    }

  else{
    printf("client accepted by the server and limit not exceeded \n");
    }
  
    printf("=== WELCOME TO THE CHATROOM ===\n");

    pthread_t send_msg_thread;
  if(pthread_create(&send_msg_thread, NULL, (void *) send_msg_handler, NULL) != 0){
        printf("ERROR: pthread\n");
    return EXIT_FAILURE;
    }

    pthread_t recv_msg_thread;
  if(pthread_create(&recv_msg_thread, NULL, (void *) recv_msg_handler, NULL) != 0){
        printf("ERROR: pthread\n");
        return EXIT_FAILURE;
    }

    while (1){
        if(flag){
            printf("\nBye\n");
            break;
    }
    }

    close(sockfd);

    return EXIT_SUCCESS;
}

編輯-2

因此，現在我將 fgets 更改為 freads 并洗掉了所有不必要的 bzero 并將 strlen 更改為 sizeof 根據 user207421、Martin James 和 stackinside 的評論建議。它終于起作用了，我同意仍有很大的優化空間，但是它現在有效，感謝您的努力。

終端中的客戶端影像

終端中的服務器端影像

客戶端代碼：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <signal.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <pthread.h>

#define LENGTH 2048
#define MAX 10000 
#define CHUNK_SIZE 512
// Global variables
volatile sig_atomic_t flag = 0;
int sockfd = 0;
char name[32];

void str_overwrite_stdout() {
  printf("%s", "> ");
  fflush(stdout);
}

void str_trim_lf (char* arr, int length) {
  int i;
  for (i = 0; i < length; i  ) { // trim \n
    if (arr[i] == '\n') {
      arr[i] = '\0';
      break;
    }
  }
}

void catch_ctrl_c_and_exit(int sig) {
    flag = 1;
}

void send_msg_handler() {
  char message[LENGTH] = {};
    char buffer[LENGTH   32] = {};

  while(1) {
    str_overwrite_stdout();
    
    fgets(message, LENGTH, stdin);
    str_trim_lf(message, LENGTH);

    if (strcmp(message, "exit") == 0) {
            break;
    } 
    
    else {
      sprintf(buffer, "%s\n", message);
      send(sockfd, buffer, sizeof(buffer), 0);
    }

        bzero(message, LENGTH);
    bzero(buffer, LENGTH   32);
  }

  catch_ctrl_c_and_exit(2);
}

void recv_msg_handler() {

    while (1) {

        int n;
        FILE *fp;
        char buff[1024],*ptr=buff;
        int bytes=0,bytes_received;
        int file_size;

        recv(sockfd, buff, CHUNK_SIZE, 0);
        file_size = atoi(buff);
        
        str_trim_lf(buff, sizeof(buff));

        printf("%s \n",buff);
        str_overwrite_stdout();
    }         
}



int main(int argc, char **argv){
    if(argc != 2){
        printf("Usage: %s <port>\n", argv[0]);
        return EXIT_FAILURE;
    }

    char *ip = "127.0.0.1";
    int port = atoi(argv[1]);

    signal(SIGINT, catch_ctrl_c_and_exit);



    struct sockaddr_in server_addr;

    /* Socket settings */
    sockfd = socket(AF_INET, SOCK_STREAM, 0);
  server_addr.sin_family = AF_INET;
  server_addr.sin_addr.s_addr = inet_addr(ip);
  server_addr.sin_port = htons(port);


  // Connect to Server
  int err = connect(sockfd, (struct sockaddr *)&server_addr, sizeof(server_addr));
  if (err == -1) {
        printf("ERROR: connect\n");
        return EXIT_FAILURE;
    }

  char exit_client[] = "exit_client";
  char buff[MAX];
    bzero(buff, sizeof(buff));
  recv(sockfd, buff, 1024, 0);

  if((strcmp(buff, exit_client) == 0)){
    printf("limit exceeded , closing the client \n");
        close(sockfd);
    return EXIT_SUCCESS;
    }

  else{
    printf("client accepted by the server and limit not exceeded \n");
    }
  
    printf("=== WELCOME TO THE CHATROOM ===\n");

    pthread_t send_msg_thread;
  if(pthread_create(&send_msg_thread, NULL, (void *) send_msg_handler, NULL) != 0){
        printf("ERROR: pthread\n");
    return EXIT_FAILURE;
    }

    pthread_t recv_msg_thread;
  if(pthread_create(&recv_msg_thread, NULL, (void *) recv_msg_handler, NULL) != 0){
        printf("ERROR: pthread\n");
        return EXIT_FAILURE;
    }

    while (1){
        if(flag){
            printf("\nBye\n");
            break;
    }
    }

    close(sockfd);

    return EXIT_SUCCESS;
}

服務器端：

#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <pthread.h>
#include <sys/types.h>
#include <signal.h>

#define MAX_CLIENTS 3
#define BUFFER_SZ 2048
#define SIZE 1024
#define CHUNK_SIZE 512

static _Atomic unsigned int cli_count = 0;
static int uid = 10;

/* Client structure */
typedef struct{
    struct sockaddr_in address;
    int sockfd;
    int uid;
    char name[32];
} client_t;

client_t *clients[MAX_CLIENTS];

void str_trim_lf (char* arr, int length) {
  int i;
  for (i = 0; i < length; i  ) { // trim \n
    if (arr[i] == '\n') {
      arr[i] = '\0';
      break;
    }
  }
}

pthread_mutex_t clients_mutex = PTHREAD_MUTEX_INITIALIZER;

void str_overwrite_stdout() {
    printf("\r%s", "> ");
    fflush(stdout);
}

void print_client_addr(struct sockaddr_in addr){
    printf("%d.%d.%d.%d",
        addr.sin_addr.s_addr & 0xff,
        (addr.sin_addr.s_addr & 0xff00) >> 8,
        (addr.sin_addr.s_addr & 0xff0000) >> 16,
        (addr.sin_addr.s_addr & 0xff000000) >> 24);
}

/* Add clients to queue */
void queue_add(client_t *cl){
    pthread_mutex_lock(&clients_mutex);

    for(int i=0; i < MAX_CLIENTS;   i){
        if(!clients[i]){
            clients[i] = cl;
            break;
        }
    }

    pthread_mutex_unlock(&clients_mutex);
}

/* Remove clients to queue */
void queue_remove(int uid){
    pthread_mutex_lock(&clients_mutex);

    for(int i=0; i < MAX_CLIENTS;   i){
        if(clients[i]){
            if(clients[i]->uid == uid){
                clients[i] = NULL;
                break;
            }
        }
    }

    pthread_mutex_unlock(&clients_mutex);
}


void send_file(int sockfd){
    int n;
    char data[SIZE] = {0};

    FILE *fp = fopen("clientid_timestamp.txt", "r");
    if (fp == NULL){
        printf("Error opening file!\n");
        exit(1);
    
    }

    char file_data[CHUNK_SIZE];
    size_t nbytes = 0;

    while ( (nbytes = fread(data, sizeof(char), CHUNK_SIZE,fp)) > 0){
        
        if (send(sockfd, data, nbytes, 0) == -1) {
        perror("[-]Error in sending file.");
        exit(1);
    }
    }
}

/* Send message to all clients except sender */
void send_message(char *s, int uid){
    pthread_mutex_lock(&clients_mutex);

    for(int i=0; i<MAX_CLIENTS;   i){
        if(clients[i]){
            if(clients[i]->uid != uid){
                printf("MESSAGE SENT TO %s:%d \n",inet_ntoa(clients[i]->address.sin_addr),ntohs(clients[i]->address.sin_port));
                send_file(clients[i]->sockfd);
            }
        }
    }

    pthread_mutex_unlock(&clients_mutex);
}

/* Handle all communication with the client */
void *handle_client(void *arg){

    char buff_out[BUFFER_SZ];
    char name[32];
    int leave_flag = 0;

    cli_count  ;
    client_t *cli = (client_t *)arg;

    // Name

    bzero(buff_out, BUFFER_SZ);

    while(1){
        if (leave_flag) {
            break;
        }

        int receive = recv(cli->sockfd, buff_out, BUFFER_SZ, 0);
        if (receive > 0){
            if(strlen(buff_out) > 0){

                FILE *f = fopen("clientid_timestamp.txt", "w");
                if (f == NULL){
                    printf("Error opening file!\n");
                    exit(1);
                }

                /* print some text */
                fprintf(f, "%s", buff_out);
                fclose(f);
                send_message(buff_out, cli->uid);
                printf("\n");
            } 
        } 

        else {
            printf("ERROR: -1\n");
            leave_flag = 1;
        }

    }

  /* Delete client from queue and yield thread */
    close(cli->sockfd);
    queue_remove(cli->uid);
    free(cli);
    cli_count--;
    pthread_detach(pthread_self());
    return NULL;
}

int main(int argc, char **argv){

    if(argc != 2){
        printf("Usage: %s <port>\n", argv[0]);
        return EXIT_FAILURE;
    }

    char *ip = "127.0.0.1";
    int port = atoi(argv[1]);
    int option = 1;
    int listenfd = 0, connfd = 0;
    struct sockaddr_in serv_addr;
    struct sockaddr_in cli_addr;
    pthread_t tid;

  /* Socket settings */
    listenfd = socket(AF_INET, SOCK_STREAM, 0);
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr = inet_addr(ip);
    serv_addr.sin_port = htons(port);

  /* Ignore pipe signals */
    signal(SIGPIPE, SIG_IGN);

    if(setsockopt(listenfd, SOL_SOCKET,(SO_REUSEPORT | SO_REUSEADDR),(char*)&option,sizeof(option)) < 0){
        perror("ERROR: setsockopt failed");
    return EXIT_FAILURE;
    }

    /* Bind */
    if(bind(listenfd, (struct sockaddr*)&serv_addr, sizeof(serv_addr)) < 0) {
        perror("ERROR: Socket binding failed");
        return EXIT_FAILURE;
    }

  /* Listen */
    if (listen(listenfd, 10) < 0) {
        perror("ERROR: Socket listening failed");
        return EXIT_FAILURE;
        }

    printf("=== WELCOME TO THE CHATROOM ===\n");

    char exit[] = "exit_client";
    char accepted[] = "accept_client";

    while(1){
        socklen_t clilen = sizeof(cli_addr);
        connfd = accept(listenfd, (struct sockaddr*)&cli_addr, &clilen);

        /* Check if max clients is reached */
        if((cli_count) == MAX_CLIENTS){
            printf("Max clients reached. Rejected: ");
            print_client_addr(cli_addr);
            printf(":%d\n", cli_addr.sin_port);
            send(connfd, exit, sizeof(exit), 0);
            close(connfd);
            continue;
        }
        else{
            
            send(connfd, accepted, sizeof(accepted), 0);
            client_t *cli = (client_t *)malloc(sizeof(client_t));
            cli->address = cli_addr;
            cli->sockfd = connfd;
            cli->uid = uid  ;

            printf("Client Connected : ");
            printf("%s:%d \n",inet_ntoa(cli->address.sin_addr),ntohs(cli->address.sin_port));
            
            /* Add client to the queue and fork thread */
            queue_add(cli);
            pthread_create(&tid, NULL, &handle_client, (void*)cli);

            /* Reduce CPU usage */
            sleep(1);
        }

        /* Client settings */
        
    }

    return EXIT_SUCCESS;
}

uj5u.com熱心網友回復：

服務器端：

  • send_file(clients[i]->uid);必定是send_file(clients[i]->sockfd);
  • fclose(f);可能應該先去 send_message(buff_out, cli->uid);

客戶端：

  • printf("%s\n",ptr);（之前if(bytes_received==-1)）應該被洗掉

還有其他不一致，未使用的變數等。此評論非常有限。

轉載請註明出處，本文鏈接：https://www.uj5u.com/houduan/462596.html

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