openssl query client certificate - c++

Question

My server is unable to get peer certificate
This works when SSL_CTX_set_verify(ctx,SSL_VERIFY_PEER,0); is removed
Adding it causes the client and server to not communicate
querying client certificate from server always gives NULL
Below is the following code:-
Header file socket.h, used in server and client sample
#ifndef SOCKET_H
#define SOCKET_H
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <set>
#include <openssl/ssl.h>
#include <openssl/err.h>
#include <thread>
int g_start=[]()->int{
system("../Servercert.sh"); /*create the certificates*/
SSL_load_error_strings(); /* load all error messages */
SSL_library_init(); /* load & register all cryptos, etc for TLS 1.2. */
return 0;
}(); //initialize this for all who use TLS 1.2
/*---------------------------------------------------------------------*/
/*--- LoadCertificates - load from files. ---*/
/*---------------------------------------------------------------------*/
void LoadCertificates(SSL_CTX* ctx, char* CertFile, char* KeyFile)
{
/* set the local certificate from CertFile */
if ( SSL_CTX_use_certificate_file(ctx, CertFile, SSL_FILETYPE_PEM) <= 0 )
{
ERR_print_errors_fp(stderr);
abort();
}
/* set the private key from KeyFile (may be the same as CertFile) */
if ( SSL_CTX_use_PrivateKey_file(ctx, KeyFile, SSL_FILETYPE_PEM) <= 0 )
{
ERR_print_errors_fp(stderr);
abort();
}
/* verify private key */
if ( !SSL_CTX_check_private_key(ctx) )
{
fprintf(stderr, "Private key does not match the public certificate\n");
abort();
}
}
SSL_CTX* InitCTX(void)
{ const SSL_METHOD *method;
SSL_CTX *ctx;
method = SSLv23_method(); /* Create new client-method instance */
ctx = SSL_CTX_new(method); /* Create new context */
if ( ctx == NULL )
{
ERR_print_errors_fp(stderr);
abort();
}
return ctx;
}
#endif // SOCKET_H
my server source file
#include <iostream>
using namespace std;
#include "socket.h"
SSL *socketsInListenMode(SSL_CTX * &ctx,int portno)
{
ctx = InitCTX(); /* initialize SSL */
LoadCertificates(ctx, "server.cert","server.key");
SSL_CTX_set_verify(ctx,SSL_VERIFY_PEER,0);
sockaddr_in serv_addr={},cli_addr={};
int sockListenfd = socket(AF_INET, SOCK_STREAM, 0);
serv_addr.sin_family = AF_INET;
serv_addr.sin_addr.s_addr = INADDR_ANY;
serv_addr.sin_port = htons(portno);
int bindret=bind(sockListenfd, (struct sockaddr *) &serv_addr, sizeof(serv_addr));
cout<<bindret<<endl;
if(bindret < 0) return 0;
listen(sockListenfd,10);
socklen_t s=0;
int newsockfd = accept(sockListenfd, (struct sockaddr *)&cli_addr, &s);
SSL *ssl = SSL_new(ctx); /* get new SSL state with context */
SSL_set_fd(ssl, newsockfd); /* set connection socket to SSL state */
SSL_accept(ssl);
close( sockListenfd );
sockListenfd = 0; //this will cause Accept to return
return ssl;
}
#include<string>
int main()
{
SSL_CTX *ctx=0;
SSL *ssl = socketsInListenMode(ctx,5000);
string s="asif";
SSL_write(ssl,s.c_str(),s.length()); //may no write the full string (but thats okay for our sample)
close(SSL_get_fd(ssl));
SSL_free(ssl);
SSL_CTX_free(ctx);
return 0;
}
my client source file
#include <iostream>
#include "../server/socket.h"
using namespace std;
int SocketConnect(int portno, string strIP)
{
struct sockaddr_in serv_addr={};
serv_addr.sin_family = AF_INET;
serv_addr.sin_addr.s_addr = inet_addr(strIP.c_str());
serv_addr.sin_port = htons(portno);
int sockfd = socket(AF_INET, SOCK_STREAM, 0);
int ret=connect(sockfd,(struct sockaddr *) &serv_addr, sizeof(serv_addr));
if(-1 == ret)
{
return -1;
}
return sockfd;
}
SSL *secureConnect(SSL_CTX * &ctx,int portno, string strIP)
{
ctx = InitCTX();
LoadCertificates(ctx, "server.cert","server.key");
SSL_CTX_set_verify(ctx,SSL_VERIFY_PEER,0);
SSL *ssl = SSL_new(ctx); /* create new SSL connection state */
int sfd=SocketConnect(portno,strIP); //socketConnect
if(-1 == sfd)
return NULL;
SSL_set_fd(ssl, sfd);
SSL_connect(ssl); //SSL connect
return ssl;
}
int main()
{
SSL_CTX *ctx=0;
SSL *ssl = secureConnect(ctx,5000,"127.0.0.1");
char buff[100]={};
SSL_read(ssl,buff,sizeof(buff));
cout<<buff<<endl<<flush;
close(SSL_get_fd(ssl));
SSL_free(ssl);
SSL_CTX_free(ctx);
return 0;
}

Answer 1

In fact is should not work without SSL_CTX_set_verify also as you have not specified where to find the CA certificates when peer certificate is verified during handshake, may be it works if you have used self-signed certificate
You should use SSL_CTX_load_verify_locations to set the CA certificates