20.8 OpenSSL 套接字SSL传输文件

有了上面的基础那么传输文件的实现就变得简单了，在传输时通常我们需要打开文件，并每次读入1024个字节的数据包，通过SSL加密传输即可，此处的文件传输功能在原生套接字章节中也进行过详细讲解，此处我们还是使用原来的密钥对，实现一个服务端等待客户端上传，当客户端连接到服务端后则开始传输文件，服务端接收文件的功能。

服务端代码部分，此处我们只需要实现一个DownloadFile函数，该函数接收一个SSL套接字，与保存文件路径即可，其他部分同上。

#include <WinSock2.h>
#include <iostream>
#include <string.h>
#include <errno.h>
#include <stdlib.h>

#include <openssl/bio.h>
#include <openssl/err.h>
#include <openssl/ssl.h>
#include <openssl/pem.h>
#include <openssl/crypto.h>

extern "C"
{
#include <openssl/applink.c>
}

#pragma comment(lib, "WS2_32.lib")
#pragma comment(lib,"libssl.lib")
#pragma comment(lib,"libcrypto.lib")

#define MAXBUF 1024

// 从路径中获取当前文件名
char* GetFileName(char* Path)
{
  if (strchr(Path, '\\'))
  {
    char ch = '\\';
    char* ref = strrchr(Path, ch) + 1;
    return ref;
  }
  else
  {
    char ch = '/';
    char* ref = strrchr(Path, ch) + 1;
    return ref;
  }
}

// 下载文件到当前目录
// 传入套接字句柄,以及放置根目录
void DownloadFile(SSL* ptr, const char* RootPath)
{
  int FileSize = 0;
  char FilePath[1024] = { 0 };
  char buffer[1024] = { 0 };

  // 接收文件长度
  SSL_read(ptr, &FileSize, 4);

  // 接收文件路径
  SSL_read(ptr, FilePath, 1024);

  // 获取到文件名
  char* FileName = GetFileName(FilePath);

  // 拼接路径
  char sz[1024] = { 0 };
  strcpy(sz, RootPath);
  strcat(sz, FileName);
  std::cout << sz << std::endl;

  // 保存文件到当前目录
  FILE* pointer = fopen(sz, "wb");

  if (pointer != NULL)
  {
    DWORD length = 0;
    DWORD total_length = 0;

    // 循环接收字节数据,每次接收1024字节
    while ((length = SSL_read(ptr, buffer, 1024)) > 0)
    {
      // 写出文件并判断是否写出成功
      if (fwrite(buffer, sizeof(char), length, pointer) < length)
      {
        break;
      }

      // 每次累加递增
      total_length += length;
      memset(buffer, 0, 1024);

      // 判断文件长度是否全部接收完毕
      if (total_length >= FileSize)
      {
        std::cout << "[传输完成] " << total_length << std::endl;
        fclose(pointer);
        return;
      }
    }
    fclose(pointer);
  }
}

int main(int argc, char** argv)
{
  SOCKET sockfd, new_fd;
  struct sockaddr_in socket_ptr, their_addr;
  char buf[MAXBUF + 1];
  SSL_CTX* ctx;

  SSL_library_init();
  OpenSSL_add_all_algorithms();
  SSL_load_error_strings();

  ctx = SSL_CTX_new(SSLv23_server_method());
  if (ctx == NULL)
  {
    return 0;
  }

  if (SSL_CTX_use_certificate_file(ctx, "d://cacert.pem", SSL_FILETYPE_PEM) <= 0)
  {
    return 0;
  }

  if (SSL_CTX_use_PrivateKey_file(ctx, "d://privkey.pem", SSL_FILETYPE_PEM) <= 0)
  {
    return 0;
  }

  if (!SSL_CTX_check_private_key(ctx))
  {
    return 0;
  }

  WSADATA wsaData;

  WSAStartup(MAKEWORD(2, 2), &wsaData);
  if (LOBYTE(wsaData.wVersion) != 2 || HIBYTE(wsaData.wVersion) != 2)
  {
    WSACleanup();
    return 0;
  }

  if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1)
  {
    return 0;
  }

  socket_ptr.sin_family = AF_INET;
  socket_ptr.sin_addr.s_addr = inet_addr("127.0.0.1");
  socket_ptr.sin_port = htons(9999);

  if (bind(sockfd, (struct sockaddr*)&socket_ptr, sizeof(struct sockaddr)) == -1)
  {
    return 0;
  }
  if (listen(sockfd, 10) == -1)
  {
    return 0;
  }

  while (1)
  {
    SSL* ssl;
    int len = sizeof(struct sockaddr);
    if ((new_fd = accept(sockfd, (struct sockaddr*)&their_addr, &len)) != -1)
    {
      printf("客户端地址: %s --> 端口: %d --> 套接字: %d \n", inet_ntoa(their_addr.sin_addr), ntohs(their_addr.sin_port), new_fd);
    }

    ssl = SSL_new(ctx);
    SSL_set_fd(ssl, new_fd);
    if (SSL_accept(ssl) == -1)
    {
      closesocket(new_fd);
      break;
    }

    // 调用下载文件函数
    DownloadFile(ssl, "d://lyshark/");

  finish:
    SSL_shutdown(ssl);
    SSL_free(ssl);
    closesocket(new_fd);
  }

  closesocket(sockfd);
  WSACleanup();
  SSL_CTX_free(ctx);

  system("pause");
  return 0;
}

客户端部分，同样代码中只需要实现一个UploadFile函数，该函数用于发送本地文件到远程，其他部分同上。

#include <WinSock2.h>
#include <iostream>
#include <string.h>
#include <errno.h>
#include <stdlib.h>

#include <openssl/bio.h>
#include <openssl/err.h>
#include <openssl/ssl.h>
#include <openssl/pem.h>
#include <openssl/crypto.h>

extern "C"
{
#include <openssl/applink.c>
}

#pragma comment(lib, "WS2_32.lib")
#pragma comment(lib,"libssl.lib")
#pragma comment(lib,"libcrypto.lib")

#define MAXBUF 1024

// 获取文件大小
int GetFileSize(std::string FileName)
{
  FILE* pointer = NULL;
  pointer = fopen(FileName.c_str(), "rb");
  if (pointer != NULL)
  {
    fseek(pointer, 0, SEEK_END);
    int size = ftell(pointer);
    fclose(pointer);
    return size;
  }
  return 0;
}

// 上传文件,传入socket套接字句柄,需要发送的文件路径
void UploadFile(SSL* ptr, const char* FilePath)
{
  int FileSize = GetFileSize(FilePath);
  char buffer[1024] = { 0 };

  // 发送文件长度
  SSL_write(ptr, &FileSize, 4);

  // 发送完整文件路径
  SSL_write(ptr, FilePath, strlen(FilePath));
  FILE* pointer = fopen(FilePath, "rb");
  if (pointer != NULL)
  {
    int length = 0;
    DWORD total_length = 0;

    while ((length = fread(buffer, sizeof(char), 1024, pointer)) > 0)
    {
      SSL_write(ptr, buffer, length);
      memset(buffer, 0, 1024);
    }
  }
}

int main(int argc, char** argv)
{
  int sockfd, len;
  struct sockaddr_in dest;
  char buffer[MAXBUF + 1] = { 0 };
  SSL_CTX* ctx;
  SSL* ssl;

  SSL_library_init();
  OpenSSL_add_all_algorithms();
  SSL_load_error_strings();

  ctx = SSL_CTX_new(SSLv23_client_method());
  if (ctx == NULL)
  {
    WSACleanup();
    return 0;
  }

  WSADATA wsaData;

  WSAStartup(MAKEWORD(2, 2), &wsaData);
  if (LOBYTE(wsaData.wVersion) != 2 || HIBYTE(wsaData.wVersion) != 2)
  {
    WSACleanup();
    return 0;
  }

  if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
  {
    WSACleanup();
    return 0;
  }

  dest.sin_family = AF_INET;
  dest.sin_addr.s_addr = inet_addr("127.0.0.1");
  dest.sin_port = htons(9999);

  if (connect(sockfd, (struct sockaddr*)&dest, sizeof(dest)) != 0)
  {
    WSACleanup();
    return 0;
  }

  ssl = SSL_new(ctx);
  SSL_set_fd(ssl, sockfd);

  if (SSL_connect(ssl) != -1)
  {
    printf("SSL 连接类型: %s \n", SSL_get_cipher(ssl));
  }

  // 发送文件
  UploadFile(ssl, "d://lyshark.exe");

finish:
  SSL_shutdown(ssl);
  SSL_free(ssl);
  closesocket(sockfd);
  SSL_CTX_free(ctx);

  system("pause");
  return 0;
}

读者可自行编译这段代码，并首先启动服务端等待传输，接着打开客户端，此时客户端中的d://lyshark.exe将被传输到服务端的特定目录下，如下图所示；