Linux C語言socket編程詳解
避免大家浪費時間找教材以及萬惡的積分下載，分享這本書，僅供學習參考：計算機網絡第七版謝希仁pdf下載
編者是在linux系統rk3308和android系統aml905上驗證的，例子不難，但跨平臺驗證時，需要注意如何編譯等一些基礎知識，比如Android系統源碼external添加新模塊。
接口簡介
socket()：創建socket
bind()：綁定socket到本地地址和端口，通常由服務端調用
listen()：TCP專用，開啓監聽模式
accept()：TCP專用，服務器等待客戶端連接，一般是阻塞態
connect()：TCP專用，客戶端主動連接服務器
send()：TCP專用，發送數據
recv()：TCP專用，接收數據
sendto()：UDP專用，發送數據到指定的IP地址和端口
recvfrom()：UDP專用，接收數據，返回數據遠端的IP地址和端口
closesocket()：關閉socket
流程
1. 編寫server
/*************************************************************************
> File Name: Server.c
> Author : Rick
> Date : 2020/05/07
************************************************************************/
#include<netinet/in.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<unistd.h>
#define SERVER_PORT 8000
#define LENGTH_OF_LISTEN_QUEUE 20
#define BUFFER_SIZE 1024
#define FILE_NAME_MAX_SIZE 512
int main(void)
{
// 聲明並初始化一個服務器端的socket地址結構
struct sockaddr_in server_addr;
bzero(&server_addr, sizeof(server_addr));
server_addr.sin_family = AF_INET;
server_addr.sin_addr.s_addr = htons(INADDR_ANY);
server_addr.sin_port = htons(SERVER_PORT);
// 創建socket，若成功，返回socket描述符
int server_socket_fd = socket(PF_INET, SOCK_STREAM, 0);
if(server_socket_fd < 0)
{
perror("Create Socket Failed:");
exit(1);
}
int opt = 1;
setsockopt(server_socket_fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));
// 綁定socket和socket地址結構
if(-1 == (bind(server_socket_fd, (struct sockaddr*)&server_addr, sizeof(server_addr))))
{
perror("Server Bind Failed:");
exit(1);
}
// socket監聽
if(-1 == (listen(server_socket_fd, LENGTH_OF_LISTEN_QUEUE)))
{
perror("Server Listen Failed:");
exit(1);
}
printf("Prepared... \n");
while(1)
{
// 定義客戶端的socket地址結構
struct sockaddr_in client_addr;
socklen_t client_addr_length = sizeof(client_addr);
// 接受連接請求，返回一個新的socket(描述符)，這個新socket用於同連接的客戶端通信
// accept函數會把連接到的客戶端信息寫到client_addr中
int new_server_socket_fd = accept(server_socket_fd, (struct sockaddr*)&client_addr, &client_addr_length);
if(new_server_socket_fd < 0)
{
perror("Server Accept Failed:");
break;
}
// recv函數接收數據到緩衝區buffer中
char buffer[BUFFER_SIZE];
bzero(buffer, BUFFER_SIZE);
if(recv(new_server_socket_fd, buffer, BUFFER_SIZE, 0) < 0)
{
perror("Server Recieve Data Failed:");
break;
}
// 然後從buffer(緩衝區)拷貝到file_name中
char file_name[FILE_NAME_MAX_SIZE+1];
bzero(file_name, FILE_NAME_MAX_SIZE+1);
strncpy(file_name, buffer, strlen(buffer)>FILE_NAME_MAX_SIZE?FILE_NAME_MAX_SIZE:strlen(buffer));
printf("%s\n", file_name);
// 打開文件並讀取文件數據
FILE *fp = fopen(file_name, "r");
if(NULL == fp)
{
printf("File:%s Not Found\n", file_name);
}
else
{
bzero(buffer, BUFFER_SIZE);
int length = 0;
// 每讀取一段數據，便將其發送給客戶端，循環直到文件讀完爲止
while((length = fread(buffer, sizeof(char), BUFFER_SIZE, fp)) > 0)
{
if(send(new_server_socket_fd, buffer, length, 0) < 0)
{
printf("Send File:%s Failed./n", file_name);
break;
}
bzero(buffer, BUFFER_SIZE);
}
// 關閉文件
fclose(fp);
printf("File:%s Transfer Successful!\n", file_name);
}
// 關閉與客戶端的連接
close(new_server_socket_fd);
}
// 關閉監聽用的socket
close(server_socket_fd);
return 0;
}
2.編寫client
/*************************************************************************
> File Name: Client.c
> Author : Rick
> Date : 2020/05/07
************************************************************************/
#include<netinet/in.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<unistd.h>
#include<arpa/inet.h>
#define SERVER_PORT 8000
#define BUFFER_SIZE 1024
#define FILE_NAME_MAX_SIZE 512
int main()
{
// 聲明並初始化一個客戶端的socket地址結構
struct sockaddr_in client_addr;
bzero(&client_addr, sizeof(client_addr));
client_addr.sin_family = AF_INET;
client_addr.sin_addr.s_addr = htons(INADDR_ANY);
client_addr.sin_port = htons(0);
// 創建socket，若成功，返回socket描述符
int client_socket_fd = socket(AF_INET, SOCK_STREAM, 0);
if(client_socket_fd < 0)
{
perror("Create Socket Failed:");
exit(1);
}
// 綁定客戶端的socket和客戶端的socket地址結構 非必需
if(-1 == (bind(client_socket_fd, (struct sockaddr*)&client_addr, sizeof(client_addr))))
{
perror("Client Bind Failed:");
exit(1);
}
// 聲明一個服務器端的socket地址結構，並用服務器那邊的IP地址及端口對其進行初始化，用於後面的連接
struct sockaddr_in server_addr;
bzero(&server_addr, sizeof(server_addr));
server_addr.sin_family = AF_INET;
if(inet_pton(AF_INET, "127.0.0.1", &server_addr.sin_addr) == 0)
{
perror("Server IP Address Error:");
exit(1);
}
server_addr.sin_port = htons(SERVER_PORT);
socklen_t server_addr_length = sizeof(server_addr);
// 向服務器發起連接，連接成功後client_socket_fd代表了客戶端和服務器的一個socket連接
if(connect(client_socket_fd, (struct sockaddr*)&server_addr, server_addr_length) < 0)
{
perror("Can Not Connect To Server IP:");
exit(0);
}
// 輸入文件名 並放到緩衝區buffer中等待發送
char file_name[FILE_NAME_MAX_SIZE+1];
bzero(file_name, FILE_NAME_MAX_SIZE+1);
printf("Please Input File Name On Server:\t");
scanf("%s", file_name);
char buffer[BUFFER_SIZE];
bzero(buffer, BUFFER_SIZE);
strncpy(buffer, file_name, strlen(file_name)>BUFFER_SIZE?BUFFER_SIZE:strlen(file_name));
// 向服務器發送buffer中的數據
if(send(client_socket_fd, buffer, BUFFER_SIZE, 0) < 0)
{
perror("Send File Name Failed:");
exit(1);
}
// 打開文件，準備寫入
FILE *fp = fopen(file_name, "w");
if(NULL == fp)
{
printf("File:\t%s Can Not Open To Write\n", file_name);
exit(1);
}
printf("Prepared... \n");
// 從服務器接收數據到buffer中
// 每接收一段數據，便將其寫入文件中，循環直到文件接收完並寫完爲止
bzero(buffer, BUFFER_SIZE);
int length = 0;
while((length = recv(client_socket_fd, buffer, BUFFER_SIZE, 0)) > 0)
{
printf("receiving... \n");
if(fwrite(buffer, sizeof(char), length, fp) < length)
{
printf("File:\t%s Write Failed\n", file_name);
break;
}
bzero(buffer, BUFFER_SIZE);
}
// 接收成功後，關閉文件，關閉socket
printf("Receive File:\t%s From Server IP Successful!\n", file_name);
fclose(fp);
close(client_socket_fd);
return 0;
}
3.編譯
略，根據實際執行硬件平臺，配置相關編譯交叉工具等。
4.驗證
/oem # ./server_3308
./server_3308
Prepared...
server_3308
File:server_3308 Transfer Successful!
參考鏈接：