Socket編程聊天應用-有解無憂

我使用 c 語言中的套接字制作了一個聊天應用程式。當我在同一臺設備上運行服務器和客戶端時，它作業正常。但是，當我在不同的設備上運行客戶端和服務器時，客戶端顯示連接錯誤。這個問題是否與ip地址有關。

服務器端代碼：

#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 100
#define BUFFER_SZ 2048

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 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 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);
}

/* 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){
                if(write(clients[i]->sockfd, s, strlen(s)) < 0){
                    perror("ERROR: write to descriptor failed");
                    break;
                }
            }
        }
    }

    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
    if(recv(cli->sockfd, name, 32, 0) <= 0 || strlen(name) <  2 || strlen(name) >= 32-1){
        printf("Didn't enter the name.\n");
        leave_flag = 1;
    } else{
        strcpy(cli->name, name);
        sprintf(buff_out, "%s has joined\n", cli->name);
        printf("%s", buff_out);
        send_message(buff_out, cli->uid);
    }

    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){
                send_message(buff_out, cli->uid);

                str_trim_lf(buff_out, strlen(buff_out));
                printf("%s -> %s\n", buff_out, cli->name);
            }
        } else if (receive == 0 || strcmp(buff_out, "exit") == 0){
            sprintf(buff_out, "%s has left\n", cli->name);
            printf("%s", buff_out);
            send_message(buff_out, cli->uid);
            leave_flag = 1;
        } 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");

    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   1) == MAX_CLIENTS){
            printf("Max clients reached. Rejected: ");
            print_client_addr(cli_addr);
            printf(":%d\n", cli_addr.sin_port);
            close(connfd);
            continue;
        }

        /* Client settings */
        client_t *cli = (client_t *)malloc(sizeof(client_t));
        cli->address = cli_addr;
        cli->sockfd = connfd;
        cli->uid = uid  ;

        /* Add client to the queue and fork thread */
        queue_add(cli);
        pthread_create(&tid, NULL, &handle_client, (void*)cli);

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

    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

// Global variables
volatile sig_atomic_t flag = 0;
int sockfd = 0;
unsigned 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() {
  unsigned char message[LENGTH] = {};
    unsigned char buffer[3000] = {};

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

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

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

void recv_msg_handler() {
    char message[LENGTH] = {};
  while (1) {
        int receive = recv(sockfd, message, LENGTH, 0);
    if (receive > 0) {
      printf("%s", message);
      str_overwrite_stdout();
    } else if (receive == 0) {
            break;
    } else {
            // -1
        }
        memset(message, 0, sizeof(message));
  }
}

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

    char *ip = "152.168.0.100";
    int port = atoi(argv[1]);

    signal(SIGINT, catch_ctrl_c_and_exit);

    printf("Please enter your name: ");
  fgets(name, 32, stdin);
  str_trim_lf(name, strlen(name));


    if (strlen(name) > 32 || strlen(name) < 2){
        printf("Name must be less than 30 and more than 2 characters.\n");
        return EXIT_FAILURE;
    }

    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;
    }

    // Send name
    send(sockfd, name, 32, 0);

    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;
}

當我在不同的機器上運行它時，它顯示連接錯誤。

uj5u.com熱心網友回復：

所以據我所知，您發布的代碼不完整，但讓我們假設，正如您所說，一切正常，它在本地機器上作業，但是當您在兩個不同的設備上運行這兩個程式時，客戶端無法連接到服務器。

然后我會問你這個問題，正如我在評論中也問過的那樣：這兩個設備是否在同一個子網中？你有一個家用路由器，兩臺設備都連接到這個路由器？

如果沒有，那就是問題所在。我不確定您對 IP 地址和子網的了解有多深，但這里有一個簡單的總結。當您查看 PC 上的 IP 地址時，您會看到路由器提供給您的私有 IP 地址。假設您有兩臺機器連接到同一個路由器，一臺的 IP 地址為 192.168.0.101，另一臺的 IP 地址為 192.168.0.102。如果 192.168.0.101 是客戶端并且想要連接到在 192.168.0.102 上運行的服務器，它應該可以正常作業。

但是假設您將服務器代碼發送給我。我在我的電腦上運行服務器，它的IP地址為192.168.0.103，你仍然在家里運行客戶端192.168.0.101。在這種情況下，您將無法連接到我的機器，因為 192.168.0.103 是我自己的路由器給出的私有 IP 地址。為此，我至少必須配置我的路由器以打開一個埠并將到達該埠的資料包轉發到我的 PC。然后我必須給你公共 IP 和埠。因此，如果防火墻配置為允許您的資料包進入我的網路，那么它可能會起作用。

當然比這要復雜一些，但這是大體的想法。

如果您不是這種情況，并且設備位于同一子網中，那么我們只需要更多資訊和完整代碼。

轉載請註明出處，本文鏈接：https://www.uj5u.com/qukuanlian/328763.html

標籤：C 插座港口聊天 IP地址

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