c语言利用openssl实现简单客户端和服务端（观察记录层最大长度）

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文章目录

前言
一、客户端实现
二、服务端实现
总结

前言

本文是使用openssl111w实现的简单客户端和服务端，主要用于观察openssl一个记录层数据包的大小。

一、客户端实现

#include <stdio.h>  
#include <stdlib.h>  
#include <string.h>  
#include <unistd.h>  
#include <sys/types.h>   
#include <sys/socket.h>  
#include <netinet/in.h>  
#include <arpa/inet.h>  
#include <openssl/ssl.h>  
#include <openssl/err.h>  
#define PORT 8000
#define SERVER_IP "127.0.0.1"
#define SERVER_KEY "./rsa_cert/serverkey.pem"
#define SERVER_CERT "./rsa_cert/servercert.pem"
#define CA_CERT "./rsa_cert/cacert.pem"
// 初始化OpenSSL库 
void init_openssl() {  SSL_load_error_strings();  OpenSSL_add_all_algorithms();  SSL_library_init();  
}  
//创建原始套接字
int create_connect_fd()
{struct sockaddr_in serv_addr;int client_fd;// 创建socketif ((client_fd = socket(AF_INET, SOCK_STREAM, 0)) < 0){printf("\n Socket creation error \n");return -1;}serv_addr.sin_family = AF_INET;serv_addr.sin_port = htons(PORT);// 使用inet_pton转换IP字符串为网络字节序if(inet_pton(AF_INET, SERVER_IP, &serv_addr.sin_addr)<=0){printf("\nInvalid address/ Address not supported \n");return -1;}// 连接服务器if (connect(client_fd, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0){printf("\nConnection Failed \n");return -1;}return client_fd;
}
//创建ssl上下文
SSL_CTX* create_ssl_ctx() {  const SSL_METHOD *method;  SSL_CTX *ctx;  method = TLSv1_2_client_method();  ctx = SSL_CTX_new(method);  if (!ctx) {  printf("Unable to create SSL context");  ERR_print_errors_fp(stderr);  return NULL;} // 加载服务器证书和私钥  if (SSL_CTX_use_certificate_file(ctx, SERVER_CERT, SSL_FILETYPE_PEM) <= 0) {  ERR_print_errors_fp(stderr); printf("load server cert failed\n"); return NULL;  }  if (SSL_CTX_use_PrivateKey_file(ctx, SERVER_KEY, SSL_FILETYPE_PEM) <= 0) {  ERR_print_errors_fp(stderr);  printf("load server key failed\n");return NULL;}  // 检查私钥和证书是否匹配  if (!SSL_CTX_check_private_key(ctx)) {  printf("cert and key mismatch\n");return NULL;}   //加载CA证书if (!SSL_CTX_load_verify_locations(ctx, CA_CERT, NULL)) {  printf("load ca cert failed\n");return NULL; }  //必须验证服务端证书，不设置则不验证SSL_CTX_set_verify(ctx, SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT, NULL);  return ctx;  
}  int main()
{SSL_CTX *ctx;SSL *ssl;int client_fd,send_len;char buf[102400] = {0};/* 初始化SSL库 */init_openssl();/* 创建SSL_CTX结构体 */ctx = create_ssl_ctx();  if(ctx == NULL){printf("create ssl ctx failed\n");return -1;}/* TCP协议连接到服务器 */client_fd = create_connect_fd(); if(client_fd < 0){printf("create client fd failed\n");return -1;}//创建ssl对象ssl = SSL_new(ctx);SSL_set_fd(ssl, client_fd);//ssl握手if (SSL_connect(ssl) == -1) {ERR_print_errors_fp(stderr);return -1;}printf("Connected with %s encryption\n", SSL_get_cipher(ssl));/* 发送数据 */send_len = SSL_write(ssl, buf, sizeof(buf));if(send_len < 0){printf("SSL_write failed\n");}else{printf("write len:%d\n", send_len);}SSL_shutdown(ssl);SSL_free(ssl);close(client_fd);SSL_CTX_free(ctx);return 0;
}

二、服务端实现

#include <stdio.h>  
#include <stdlib.h>  
#include <string.h>  
#include <unistd.h>  
#include <sys/types.h>   
#include <sys/socket.h>  
#include <netinet/in.h>  
#include <arpa/inet.h>  
#include <openssl/ssl.h>  
#include <openssl/err.h>  
#define PORT 8000
#define SERVER_KEY "./rsa_cert/serverkey.pem"
#define SERVER_CERT "./rsa_cert/servercert.pem"
#define CA_CERT "./rsa_cert/cacert.pem"
// 初始化OpenSSL库  
void init_openssl() {  SSL_load_error_strings();  OpenSSL_add_all_algorithms();  SSL_library_init();  
}  // 创建ssl上下文 
SSL_CTX* create_ssl_ctx() {  const SSL_METHOD *method;  SSL_CTX *ctx;  OpenSSL_add_ssl_algorithms();  method = TLSv1_2_server_method();  ctx = SSL_CTX_new(method);  if (!ctx) {  printf("Unable to create SSL context");  ERR_print_errors_fp(stderr);  return NULL;}  // 加载服务器证书和私钥  if (SSL_CTX_use_certificate_file(ctx, SERVER_CERT, SSL_FILETYPE_PEM) <= 0) {  ERR_print_errors_fp(stderr); printf("load server cert failed\n"); return NULL;  }  if (SSL_CTX_use_PrivateKey_file(ctx, SERVER_KEY, SSL_FILETYPE_PEM) <= 0) {  ERR_print_errors_fp(stderr);  printf("load server key failed\n");return NULL;}  // 检查私钥和证书是否匹配  if (!SSL_CTX_check_private_key(ctx)) {  printf("cert and key mismatch\n");return NULL;}  if (!SSL_CTX_load_verify_locations(ctx, CA_CERT, NULL)) {  printf("load ca cert failed\n");return NULL; }  //必须验证服务端证书，不设置则不验证SSL_CTX_set_verify(ctx, SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT, NULL);  return ctx;  
}  
//创建监听套接字
int create_listenfd()
{int listen_fd;struct sockaddr_in server_addr;int opt = 1;if ((listen_fd = socket(AF_INET, SOCK_STREAM, 0)) == 0){printf("socket failed\n");return -1;}// 设置socket选项，允许重复使用地址if (setsockopt(listen_fd, SOL_SOCKET, SO_REUSEADDR,&opt, sizeof(opt))){printf("setsockopt failed\n");return -1;}server_addr.sin_family = AF_INET;server_addr.sin_addr.s_addr = INADDR_ANY;server_addr.sin_port = htons(PORT);// 绑定socket到指定地址和端口if (bind(listen_fd, (struct sockaddr *)&server_addr, sizeof(server_addr))<0){printf("bind failed\n");return -1;}// 开始监听，最大等待队列长度为5if (listen(listen_fd, 5) < 0){printf("listen failed\n");return -1;}return listen_fd;
}int main() {  int listen_fd,con_fd,recv_len;char buf[20480] = {0};init_openssl();  //创建ssl上下文SSL_CTX *ctx = create_ssl_ctx();  if(ctx == NULL){printf("create ssl ctx failed\n");return -1;}//创建监听套接字listen_fd = create_listenfd();if(listen_fd < 0){printf("create listen fd failed\n");return -1;}while(1) {struct sockaddr_in client_addr;socklen_t len = sizeof(client_addr);SSL *ssl;//等待客户端发起tcp链接con_fd = accept(listen_fd, (struct sockaddr*)&client_addr, &len);if(con_fd < 0){printf("create connetct fd failed\n");return -1;}printf("create connect fd success\n");ssl = SSL_new(ctx);SSL_set_fd(ssl, con_fd);//等待ssl握手if (SSL_accept(ssl) == -1) {ERR_print_errors_fp(stderr);return -1;} printf("SSL Connection established\n");for (;;) {//读取ssl数据recv_len = SSL_read(ssl, buf, sizeof(buf));if (recv_len > 0)printf("Received_len:%d \n", recv_len);else {ERR_print_errors_fp(stderr);break;}}SSL_shutdown(ssl);SSL_free(ssl);close(con_fd);}SSL_CTX_free(ctx);close(listen_fd);return 0;  
}