实践–聊天室

使用poll函数实现IO多路复用，实现一个聊天室。

目录结构

代码实现

• Makefile

CC = gcc

CFLAGS = -Iinclude -Wall -g

SRC_DIR = src
INC_DIR = include
OBJ_DIR = obj

SRCS = $(wildcard $(SRC_DIR)/*.c)

OBJS = $(patsubst $(SRC_DIR)/%.c,$(OBJ_DIR)/%.o,$(SRCS))

TARGET = chat_server

all: $(TARGET)

$(TARGET): $(OBJS)
    $(CC) $(CFLAGS) -o $@ $^

$(OBJ_DIR)/%.o: $(SRC_DIR)/%.c | $(OBJ_DIR)
    $(CC) $(CFLAGS) -c -o $@ $^

$(OBJ_DIR):
    mkdir -p $(OBJ_DIR)

clean:
    rm -rf $(OBJ_DIR) chat_server

.PHONY: all clean

server.h

#ifndef SERVER_H
#define SERVER_H
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <poll.h>
#include <errno.h>
#include <arpa/inet.h>
#include <string.h>
#define PORT 8099
#define MAXCLIENTS 100
int create_server_socket();
#endif // SERVER_H

client_handler.h

#ifndef CLIENT_HANDLER_H
#define CLIENT_HANDLER_H
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <poll.h>
#include <errno.h>
#define BUFFER_SIZE 1024
void handle_new_connection(int server_socket, struct pollfd *fds, int *nfds);
void handle_client_message(struct pollfd *fds, int *nfds, int i);
void broadcast_message(struct pollfd *fds, int nfds, int sender_fd, const char *message, ssize_t message_len);
#endif

server.c

#include "server.h"
#include "client_handler.h"

int create_server_socket()
{
    int server_socket = socket(PF_INET, SOCK_STREAM, 0);
    if (server_socket == -1)
    {
        perror("socket");
        exit(EXIT_FAILURE);
    }
    struct sockaddr_in server_addr;

    server_addr.sin_family = PF_INET;
    server_addr.sin_port = htons(PORT);
    server_addr.sin_addr.s_addr = INADDR_ANY;

    if(bind(server_socket,(struct sockaddr*)&server_addr,sizeof(server_addr)) == -1) {
        perror("bind");
        close(server_socket);
        exit(EXIT_FAILURE);
    }

    if(listen(server_socket,10) == -1) {
        perror("listen");
        close(server_socket);
        exit(EXIT_FAILURE);
    }

    return server_socket;
}

client_handler.c

#include "client_handler.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <errno.h>

void handle_new_connection(int server_socket, struct pollfd *fds, int *nfds)
{
    struct sockaddr_in client_addr;
    socklen_t clientaddr_len = sizeof(client_addr);
    int client_socket = accept(server_socket, (struct sockaddr *)&client_addr, &clientaddr_len);
    if (client_socket == -1)
    {
        perror("accept");
        exit(EXIT_FAILURE);
    }
    else
    {
        char client_ip[INET_ADDRSTRLEN];
        inet_ntop(AF_INET, &client_addr.sin_addr, client_ip, sizeof(client_ip));
        printf("New connection accepted from %s:%d\n", client_ip, ntohs(client_addr.sin_port));
        char newbuffer[BUFFER_SIZE];
        sprintf(newbuffer,"Welcome,Friends,You are login in my server now,your ip is:%s\n", client_ip);
        send(client_socket,newbuffer,strlen(newbuffer),0);
        fds[*nfds].fd = client_socket;
        fds[*nfds].events = POLLIN;
        (*nfds)++;
    }
}

void handle_client_message(struct pollfd *fds, int *nfds, int i)
{
    char buffer[BUFFER_SIZE];
    ssize_t bytes_received = recv(fds[i].fd, buffer, BUFFER_SIZE - 1, 0);
    if (bytes_received > 0)
    {
        buffer[bytes_received] = '\0';
        printf("Received message: %s\n", buffer);

        // 获取发送者的 IP 和端口
        struct sockaddr_in sender_addr;
        socklen_t addr_len = sizeof(sender_addr);
        getpeername(fds[i].fd, (struct sockaddr *)&sender_addr, &addr_len);
        char sender_ip[INET_ADDRSTRLEN];
        inet_ntop(AF_INET, &sender_addr.sin_addr, sender_ip, sizeof(sender_ip));
        int sender_port = ntohs(sender_addr.sin_port);

        // 计算前缀长度和剩余空间
        const char *prefix_format = "From %s:%d: ";
        int prefix_len = snprintf(NULL, 0, prefix_format, sender_ip, sender_port);
        int remaining_space = BUFFER_SIZE - prefix_len - 1;

        // 确保 buffer 不会超过 remaining_space
        if (bytes_received > remaining_space)
        {
            bytes_received = remaining_space;
            buffer[bytes_received] = '\0'; // 确保 buffer 以空字符结尾
        }

        // 创建新的消息缓冲区并添加发送者的 IP 和端口信息
        char newbuffer[BUFFER_SIZE];
        snprintf(newbuffer, sizeof(newbuffer), prefix_format, sender_ip, sender_port);
        strncat(newbuffer, buffer, remaining_space);

        broadcast_message(fds, *nfds, fds[i].fd, newbuffer, strlen(newbuffer));
    }
    else if (bytes_received == 0)
    {
        printf("Client disconnected\n");
        close(fds[i].fd);
        fds[i] = fds[*nfds - 1];
        (*nfds)--;
    }
    else
    {
        perror("recv");
        close(fds[i].fd);
        fds[i] = fds[*nfds - 1];
        (*nfds)--;
    }
}

void broadcast_message(struct pollfd *fds, int nfds, int sender_fd, const char *message, ssize_t message_len)
{
    for (int i = 1; i < nfds; i++)
    {
        if (fds[i].fd != sender_fd)
        {
            send(fds[i].fd, message, message_len, 0);
        }
    }
}

main.c

#include "server.h"
#include "client_handler.h"

#define MAX_CLIENTS 100

int main() {
    int server_socket = create_server_socket(PORT);
    struct pollfd fds[MAX_CLIENTS];
    int nfds = 1;

    fds[0].fd = server_socket;
    fds[0].events = POLLIN;

    printf("Server listening on port %d\n", PORT);

    while (1) {
        int poll_count = poll(fds, nfds, -1);
        if (poll_count == -1) {
            perror("poll");
            close(server_socket);
            exit(EXIT_FAILURE);
        }

        for (int i = 0; i < nfds; i++) {
            if (fds[i].revents & POLLIN) {
                if (fds[i].fd == server_socket) {
                    handle_new_connection(server_socket, fds, &nfds);
                } else {
                    handle_client_message(fds, &nfds, i);
                }
            }
        }
    }

    close(server_socket);
    return 0;
}

演示