我已经从网上找到的一些教程中编写了一组简单的 SSL 客户端/服务器程序 - 这些工作正常。我无法理解的是事物的客户端（见下文）
从客户端连接到 SSL 服务器的代码来看，它似乎盲目地接受了它提供的证书，然后使用它来加密/解密发送到和从该对发送的数据。
不应该有客户端验证服务器证书以供使用吗？我的意思是我可以用任何新的证书更改/交换服务器端证书，并让它连接起来而不需要太多的wimper？这是一种安全的连接方法吗？（或者我 - 我怀疑 - 错过了什么）
非常感谢
FR
void LoadCertificates(SSL_CTX* ctx, char* CertFile, char* KeyFile);
int OpenConnection(const char *hostname, int port);
void ShowCerts(SSL* ssl);
SSL_CTX* InitCTX(void);
int main(int count, char *strings[]) {
char *hostname, *portnum;
char buf[1024];
SSL_CTX *ctx;
SSL *ssl;
int server;
int bytes;
if ( count != 3 ) {
printf("usage: %s <hostname> <portnum>\n", strings[0]);
exit(0);
} // if
hostname=strings[1];
portnum=strings[2];
printf("\nSSL Client 0.1\n~~~~~~~~~~~~~~~\n\n");
// Init. the SSL lib
SSL_library_init();
ctx = InitCTX();
printf("Client SSL lib init complete\n");
// Open the connection as normal
server = OpenConnection(hostname, atoi(portnum));
// Create new SSL connection state
ssl = SSL_new(ctx);
// Attach the socket descriptor
SSL_set_fd(ssl, server);
// Perform the connection
if ( SSL_connect(ssl) != FAIL ) {
char *msg = "Here is some data";
printf("Connected with %s encryption\n", SSL_get_cipher(ssl));
// Print any certs
ShowCerts(ssl);
// Encrypt & send message */
SSL_write(ssl, msg, strlen(msg));
// Get reply & decrypt
bytes = SSL_read(ssl, buf, sizeof(buf));
buf[bytes] = 0;
printf("Received: '%s'\n\n", buf);
// Release connection state
SSL_free(ssl);
} // if
else ERR_print_errors_fp(stderr);
// Close socket
close(server);
// Release context
SSL_CTX_free(ctx);
return 0;
} // main
SSL_CTX* InitCTX(void) {
SSL_METHOD const *method;
SSL_CTX *ctx;
// Load cryptos, et.al.
OpenSSL_add_all_algorithms();
// Bring in and register error messages
SSL_load_error_strings();
// Create new client-method instance
method = SSLv3_client_method();
// Create new context
ctx = SSL_CTX_new(method);
if ( ctx == NULL ) {
ERR_print_errors_fp(stderr);
abort();
} // if
return ctx;
} //InitCTX
int OpenConnection(const char *hostname, int port) {
int sd;
struct hostent *host;
struct sockaddr_in addr;
if ( (host = gethostbyname(hostname)) == NULL ) {
perror(hostname);
abort();
} // if
sd = socket(PF_INET, SOCK_STREAM, 0);
bzero(&addr, sizeof(addr));
addr.sin_family = AF_INET;
addr.sin_port = htons(port);
addr.sin_addr.s_addr = *(long*)(host->h_addr);
if ( connect(sd, (struct sockaddr*)&addr, sizeof(addr)) != 0 ) {
close(sd);
perror(hostname);
abort();
} // if
return sd;
} // OpenConnection
void ShowCerts(SSL* ssl) {
X509 *cert;
char *line;
cert = SSL_get_peer_certificate(ssl); /* get the server's certificate */
if ( cert != NULL ) {
printf("\nServer certificate:\n");
line = X509_NAME_oneline(X509_get_subject_name(cert), 0, 0);
printf("Subject: %s\n", line);
// Free the malloc'ed string
free(line);
line = X509_NAME_oneline(X509_get_issuer_name(cert), 0, 0);
printf("Issuer: %s\n", line);
// Free the malloc'ed string
free(line);
// Free the malloc'ed certificate copy
X509_free(cert);
} // if
else printf("No certificates.\n");
} // ShowCerts