[Ethernet]网卡驱动 -- UDP通信

最近在搞网络驱动，在网上找到几个比较好的例程，自己又整理了下，代码贴在下面：
这个代码自己加了握手，实测下来md5是对的。
不记得是哪找的了，好象是一个叫什么程序员代码网之类的，侵删。

// client.c
#include<sys/types.h> 
#include<sys/socket.h> 
#include<unistd.h> 
#include<netinet/in.h> 
#include<arpa/inet.h> 
#include<stdio.h> 
#include<stdlib.h> 
#include<errno.h> 
#include<netdb.h> 
#include<stdarg.h> 
#include<string.h> 
  
#define SERVER_PORT 1234
#define BUFFER_SIZE 4096
#define FILE_NAME_MAX_SIZE 512 
  
/* 包头 */
typedef struct 
{ 
  int id; 
  int buf_size; 
}PackInfo; 
  
/* 接收包 */
struct RecvPack 
{ 
  PackInfo head; 
  char buf[BUFFER_SIZE]; 
} data; 
  
  
int main(int argc, char **argv) 
{ 
  int id = 1; 

  if(argc != 2)
  {
    printf("usage: ./client <ipaddress>\n");
    exit(0);
  }
  
  /* 服务端地址 */
  struct sockaddr_in server_addr; 
  bzero(&server_addr, sizeof(server_addr)); 
  server_addr.sin_family = AF_INET; 
  server_addr.sin_port = htons(SERVER_PORT); 
  if(inet_pton(AF_INET, argv[1], &server_addr.sin_addr) <= 0)
  {
    perror("inet_pton:\n");
    exit(1);
  }
  // server_addr.sin_addr.s_addr = inet_addr(argv[1]); 
  socklen_t server_addr_length = sizeof(server_addr); 
  
  /* 创建socket */
  int client_socket_fd = socket(AF_INET, SOCK_DGRAM, 0); 
  if(client_socket_fd < 0) 
  { 
    perror("Create Socket Failed:"); 
    exit(1); 
  } 
  
  /* 输入文件名到缓冲区 */
  char file_name[FILE_NAME_MAX_SIZE+1]; 
  bzero(file_name, FILE_NAME_MAX_SIZE+1); 
  printf("Please Input File Name On Server: "); 
  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)); 
  
  /* 发送文件名 */
  if(sendto(client_socket_fd, buffer, BUFFER_SIZE,0,(struct sockaddr*)&server_addr, server_addr_length) < 0) 
  { 
    perror("Send File Name Failed:"); 
    exit(1); 
  } 
  
  /* 打开文件，准备写入 */
  FILE *fp = fopen(file_name, "w"); 
  if(NULL == fp) 
  { 
    printf("File:\t%s Can Not Open To Write\n", file_name);  
    exit(1); 
  } 
  
  /* 从服务器接收数据，并写入文件 */
  int len = 0; 
  while(1) 
  { 
    PackInfo pack_info; 
  
    if((len = recvfrom(client_socket_fd, (char*)&data, sizeof(data), 0, (struct sockaddr*)&server_addr,&server_addr_length)) > 0) 
    { 
      if(data.head.id == id) 
      { 
        pack_info.id = data.head.id; 
        pack_info.buf_size = data.head.buf_size; 
        printf("recv id:%d.\n", id); 
        ++id; 
        /* 发送数据包确认信息 */
        if(sendto(client_socket_fd, (char*)&pack_info, sizeof(pack_info), 0, (struct sockaddr*)&server_addr, server_addr_length) < 0) 
        { 
          printf("Send confirm information failed!"); 
        } 
        /* 写入文件 */
        if(fwrite(data.buf, sizeof(char), data.head.buf_size, fp) < data.head.buf_size) 
        { 
          printf("File:\t%s Write Failed\n", file_name); 
          break; 
        } 
        fflush(fp);
      } 
      else if(data.head.id < id) /* 如果是重发的包 */
      { 
        pack_info.id = data.head.id; 
        pack_info.buf_size = data.head.buf_size; 
        /* 重发数据包确认信息 */
        if(sendto(client_socket_fd, (char*)&pack_info, sizeof(pack_info), 0, (struct sockaddr*)&server_addr, server_addr_length) < 0) 
        { 
          printf("Send confirm information failed!"); 
        } 
      } 
      else
      { 
  
      } 
    } 
    else
    { 
      break; 
    } 
  } 
  
  printf("Receive File:\t%s From Server IP Successful!\n", file_name); 
  fclose(fp); 
  close(client_socket_fd); 
  return 0; 
}

// server.c
#include<sys/types.h> 
#include<sys/socket.h> 
#include<unistd.h> 
#include<netinet/in.h> 
#include<arpa/inet.h> 
#include<stdio.h> 
#include<stdlib.h> 
#include<errno.h> 
#include<netdb.h> 
#include<stdarg.h> 
#include<string.h> 
  
#define SERVER_PORT 8000 
#define BUFFER_SIZE 4096
#define FILE_NAME_MAX_SIZE 512 
  
/* 包头 */
typedef struct
{ 
  int id; 
  int buf_size; 
}PackInfo; 
  
/* 接收包 */
struct SendPack 
{ 
  PackInfo head; 
  char buf[BUFFER_SIZE]; 
} data; 
  
  
int main() 
{ 
  /* 发送id */
  int send_id = 0; 
  
  /* 接收id */
  int receive_id = 0; 
  
  /* 创建UDP套接口 */
  struct sockaddr_in server_addr; 
  bzero(&server_addr, sizeof(server_addr)); 
  server_addr.sin_family = AF_INET; 
  server_addr.sin_addr.s_addr = htonl(INADDR_ANY); 
  server_addr.sin_port = htons(SERVER_PORT); 
  
  /* 创建socket */
  int server_socket_fd = socket(AF_INET, SOCK_DGRAM, 0); 
  if(server_socket_fd == -1) 
  { 
    perror("Create Socket Failed:"); 
    exit(1); 
  } 
  
  /* 绑定套接口 */
  if(-1 == (bind(server_socket_fd,(struct sockaddr*)&server_addr,sizeof(server_addr)))) 
  { 
    perror("Server Bind Failed:"); 
    exit(1); 
  } 
  
  /* 数据传输 */
  while(1) 
  {   
    /* 定义一个地址，用于捕获客户端地址 */
    struct sockaddr_in client_addr; 
    socklen_t client_addr_length = sizeof(client_addr); 
  
    /* 接收数据 */
    char buffer[BUFFER_SIZE]; 
    bzero(buffer, BUFFER_SIZE); 
    if(recvfrom(server_socket_fd, buffer, BUFFER_SIZE,0,(struct sockaddr*)&client_addr, &client_addr_length) == -1) 
    { 
      perror("Receive Data Failed:"); 
      exit(1); 
    } 
  
    /* 从buffer中拷贝出file_name */
    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); 
  
    /* 打开文件 */
    FILE *fp = fopen(file_name, "r"); 
    if(NULL == fp) 
    { 
      printf("File:%s Not Found.\n", file_name); 
    } 
    else
    { 
      int len = 0; 
      /* 每读取一段数据，便将其发给客户端 */
      while(1) 
      { 
        PackInfo pack_info; 
  
        if(receive_id == send_id) 
        { 
          ++send_id; 
          if((len = fread(data.buf, sizeof(char), BUFFER_SIZE, fp)) > 0) 
          { 
            data.head.id = send_id; /* 发送id放进包头,用于标记顺序 */
            data.head.buf_size = len; /* 记录数据长度 */
            if(sendto(server_socket_fd, (char*)&data, sizeof(data), 0, (struct sockaddr*)&client_addr, client_addr_length) < 0) 
            { 
              perror("Send File Failed:"); 
              break; 
            } 
            printf("send id:%d.\n", send_id); 
            /* 接收确认消息 */
            recvfrom(server_socket_fd, (char*)&pack_info, sizeof(pack_info), 0, (struct sockaddr*)&client_addr, &client_addr_length); 
            receive_id = pack_info.id;  
          } 
          else
          { 
            break; 
          } 
        } 
        else
        { 
          /* 如果接收的id和发送的id不相同,重新发送 */
          if(sendto(server_socket_fd, (char*)&data, sizeof(data), 0, (struct sockaddr*)&client_addr, client_addr_length) < 0) 
          { 
            perror("Send File Failed:"); 
            break; 
          } 
          /* 接收确认消息 */
          recvfrom(server_socket_fd, (char*)&pack_info, sizeof(pack_info), 0, (struct sockaddr*)&client_addr, &client_addr_length); 
          receive_id = pack_info.id;  
        } 
      } 
      /* 关闭文件 */
      fclose(fp); 
      printf("File:%s Transfer Successful!\n", file_name); 
    } 
  } 
  close(server_socket_fd); 
  return 0; 
}