secure socket programming

프로그래밍/C++ 2015. 8. 11. 14:00 |

secure socket programming

 

server

 Collapse source
//SSL-Server.c
#include <stdio.h>
#include <errno.h>
#include <unistd.h>
#include <malloc.h>
#include <string.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <resolv.h>
#include <openssl/ssl.h>
#include <openssl/err.h>
  
#define FAIL    -1
  
int OpenListener(int port)
{   int sd;
    struct sockaddr_in addr;
  
    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 = INADDR_ANY;
    if ( bind(sd, (struct sockaddr*)&addr, sizeof(addr)) != 0 )
    {
        perror("can't bind port");
        abort();
    }
    if ( listen(sd, 10) != 0 )
    {
        perror("Can't configure listening port");
        abort();
    }
    return sd;
}
  
SSL_CTX* InitServerCTX(void)
{   SSL_METHOD *method;
    SSL_CTX *ctx;
  
    OpenSSL_add_all_algorithms();  /* load & register all cryptos, etc. */
    SSL_load_error_strings();   /* load all error messages */
    method = SSLv23_server_method();  /* create new server-method instance */
    ctx = SSL_CTX_new(method);   /* create new context from method */
    if ( ctx == NULL )
    {
        ERR_print_errors_fp(stderr);
        abort();
    }
    return ctx;
}
  
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();
    }
}
  
void ShowCerts(SSL* ssl)
{   X509 *cert;
    char *line;
  
    cert = SSL_get_peer_certificate(ssl); /* Get certificates (if available) */
    if ( cert != NULL )
    {
        printf("Server certificates:\n");
        line = X509_NAME_oneline(X509_get_subject_name(cert), 0, 0);
        printf("Subject: %s\n", line);
        free(line);
        line = X509_NAME_oneline(X509_get_issuer_name(cert), 0, 0);
        printf("Issuer: %s\n", line);
        free(line);
        X509_free(cert);
    }
    else
        printf("No certificates.\n");
}
  
void Servlet(SSL* ssl) /* Serve the connection -- threadable */
{   char buf[1024];
    char reply[1024];
    int sd, bytes;
    const char* HTMLecho="<html><body><pre>%s</pre></body></html>\n\n";
  
    if ( SSL_accept(ssl) == FAIL )     /* do SSL-protocol accept */
        ERR_print_errors_fp(stderr);
    else
    {
        ShowCerts(ssl);        /* get any certificates */
        bytes = SSL_read(ssl, buf, sizeof(buf)); /* get request */
        if ( bytes > 0 )
        {
            buf[bytes] = 0;
            printf("Client msg: \"%s\"\n", buf);
            sprintf(reply, HTMLecho, buf);   /* construct reply */
            SSL_write(ssl, reply, strlen(reply)); /* send reply */
        }
        else
            ERR_print_errors_fp(stderr);
    }
    sd = SSL_get_fd(ssl);       /* get socket connection */
    SSL_free(ssl);         /* release SSL state */
    close(sd);          /* close connection */
}
  
int main(int count, char *strings[])
{   SSL_CTX *ctx;
    int server;
    char *portnum;
  
    if ( count != 2 )
    {
        printf("Usage: %s <portnum>\n", strings[0]);
        exit(0);
    }
    SSL_library_init();
  
    portnum = strings[1];
    ctx = InitServerCTX();        /* initialize SSL */
    LoadCertificates(ctx, "mycert.pem", "mycert.pem"); /* load certs */
    server = OpenListener(atoi(portnum));    /* create server socket */
    while (1)
    {   struct sockaddr_in addr;
        socklen_t len = sizeof(addr);
        SSL *ssl;
  
        int client = accept(server, (struct sockaddr*)&addr, &len);  /* accept connection as usual */
        printf("Connection: %s:%d\n",inet_ntoa(addr.sin_addr), ntohs(addr.sin_port));
        ssl = SSL_new(ctx);              /* get new SSL state with context */
        SSL_set_fd(ssl, client);      /* set connection socket to SSL state */
        Servlet(ssl);         /* service connection */
    }
    close(server);          /* close server socket */
    SSL_CTX_free(ctx);         /* release context */
    return 0;
}

컴파일 :

gcc -Wall -o server server.c -lssl -lcrypto

 

 

 

 

client

 Collapse source
#include <stdio.h>
#include <errno.h>
#include <unistd.h>
#include <malloc.h>
#include <string.h>
#include <sys/socket.h>
#include <resolv.h>
#include <netdb.h>
#include <openssl/ssl.h>
#include <openssl/err.h>
  
#define FAIL    -1
  
int OpenConnection(const char *hostname, int port)
{   int sd;
    struct hostent *host;
    struct sockaddr_in addr;
  
    if ( (host = gethostbyname(hostname)) == NULL )
    {
        perror(hostname);
        abort();
    }
    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();
    }
    return sd;
}
  
SSL_CTX* InitCTX(void)
{   SSL_METHOD *method;
    SSL_CTX *ctx;
  
    OpenSSL_add_all_algorithms();  /* Load cryptos, et.al. */
    SSL_load_error_strings();   /* Bring in and register error messages */
    method = SSLv23_client_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;
}
  
void ShowCerts(SSL* ssl)
{   X509 *cert;
    char *line;
  
    cert = SSL_get_peer_certificate(ssl); /* get the server's certificate */
    if ( cert != NULL )
    {
        printf("Server certificates:\n");
        line = X509_NAME_oneline(X509_get_subject_name(cert), 0, 0);
        printf("Subject: %s\n", line);
        free(line);       /* free the malloc'ed string */
        line = X509_NAME_oneline(X509_get_issuer_name(cert), 0, 0);
        printf("Issuer: %s\n", line);
        free(line);       /* free the malloc'ed string */
        X509_free(cert);     /* free the malloc'ed certificate copy */
    }
    else
        printf("No certificates.\n");
}
  
int main(int count, char *strings[])
{   SSL_CTX *ctx;
    int server;
    SSL *ssl;
    char buf[1024];
    int bytes;
    char *hostname, *portnum;
  
    if ( count != 3 )
    {
        printf("usage: %s <hostname> <portnum>\n", strings[0]);
        exit(0);
    }
    SSL_library_init();
 hostname=strings[1];
 portnum=strings[2];
  
    ctx = InitCTX();
    server = OpenConnection(hostname, atoi(portnum));
    ssl = SSL_new(ctx);      /* create new SSL connection state */
    SSL_set_fd(ssl, server);    /* attach the socket descriptor */
    if ( SSL_connect(ssl) == FAIL )   /* perform the connection */
        ERR_print_errors_fp(stderr);
    else
    {   char *msg = "Hello???";
  
        printf("Connected with %s encryption\n", SSL_get_cipher(ssl));
        ShowCerts(ssl);        /* get any certs */
        SSL_write(ssl, msg, strlen(msg));   /* encrypt & send message */
        bytes = SSL_read(ssl, buf, sizeof(buf)); /* get reply & decrypt */
        buf[bytes] = 0;
        printf("Received: \"%s\"\n", buf);
        SSL_free(ssl);        /* release connection state */
    }
    close(server);         /* close socket */
    SSL_CTX_free(ctx);        /* release context */
    return 0;
}
 

컴파일 :

gcc -Wall -o server client.c -lssl -lcrypto

references:

[1] Secure programming with the OpenSSL API, Part 1: Overview of the API : http://www.ibm.com/developerworks/library/l-openssl.html

[2] Korean Version of [1] : http://hasu0707.tistory.com/153

[3] Secure Server Client using OpenSSL in C : http://simplestcodings.blogspot.kr/2010/08/secure-server-client-using-openssl-in-c.html

[4] HTTPS와 SSL 인증서 : http://opentutorials.org/course/228/4894

[5] SSL/TLS Programming : http://www.cs.odu.edu/~cs772/fall08/lectures/ssl_programming.pdf

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