Reputation: 25
I am having a partial failure with my code in that I can establish non-secure connections to places such as www.hp.com and www.google.com, but when adding SSL to the socket I can no longer connect to www.google.com even though I can still connect to www.hp.com
In response to this I did a fair bit of research and came up with mixed answers. I tried testing different sites, and the results were spotty. So I feel like I am missing a crucial portion of the SSL handshake here that is not readily apparent (at least to me).
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <resolv.h>
#include <netdb.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <openssl/bio.h>
#include <openssl/ssl.h>
#include <openssl/err.h>
#include <openssl/pem.h>
#include <openssl/x509.h>
#include <openssl/x509_vfy.h>
#include <errno.h>
#define SW_SUCCESS 1
#define SW_ERROR 0
typedef struct socket_info
{
int SocketHandle;
unsigned long AddressLong;
unsigned short Port;
char Host[256];
char Address[16];
char Request[256];
char Agent[128];
char Headers[512];
SSL *SecureHandle;
SSL_CTX *SecureContext;
const SSL_METHOD *SecureMethod;
BIO *SecureCertificate;
} SOCKETINFO, *PSOCKETINFO, *LPSOCKETINFO;
int secinit()
{
OpenSSL_add_all_algorithms();
ERR_load_BIO_strings();
ERR_load_crypto_strings();
SSL_load_error_strings();
return SW_SUCCESS;
}
int rawclose(struct socket_info *psi)
{
return (!close(psi->SocketHandle) ? SW_SUCCESS : SW_ERROR);
}
int secclose(struct socket_info *psi)
{
SSL_free(psi->SecureHandle);
SSL_CTX_free(psi->SecureContext);
return (rawclose(psi) ? SW_SUCCESS : SW_ERROR);
}
int rawconnect(struct socket_info *psi)
{
struct hostent *host;
struct sockaddr_in addr;
if ( (host = gethostbyname(psi->Host)) == NULL ) return SW_ERROR;
if ( (psi->SocketHandle = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0 )
{
psi->SocketHandle = 0;
return SW_ERROR;
}
memset(&addr, 0, sizeof(addr));
addr.sin_family = AF_INET;
addr.sin_port = htons(psi->Port);
addr.sin_addr.s_addr = *(long *)host->h_addr;
if ( connect(psi->SocketHandle, (struct sockaddr *)&addr, sizeof(struct sockaddr)) == -1 )
{
psi->SocketHandle = 0;
return SW_ERROR;
}
return SW_SUCCESS;
}
int secconnect(struct socket_info *psi)
{
// Initialise certificate BIO.
psi->SecureCertificate = BIO_new(BIO_s_file());
if ( SSL_library_init() < 0 ) return SW_ERROR;
// Initialise SSL method and deprecate SSLv2.
psi->SecureMethod = SSLv23_client_method();
if ( (psi->SecureContext = SSL_CTX_new(psi->SecureMethod)) == NULL ) return SW_ERROR;
SSL_CTX_set_options(psi->SecureContext, SSL_OP_NO_SSLv2);
psi->SecureHandle = SSL_new(psi->SecureContext);
// Connect to host with raw socket.
if ( !rawconnect(psi) )
{
SSL_free(psi->SecureHandle);
SSL_CTX_free(psi->SecureContext);
return SW_ERROR;
}
// Upgrade socket to SSL enabled.
SSL_set_fd(psi->SecureHandle, psi->SocketHandle);
if ( SSL_connect(psi->SecureHandle) != 1 )
{
SSL_free(psi->SecureHandle);
close(psi->SocketHandle);
SSL_CTX_free(psi->SecureContext);
return SW_ERROR;
}
return SW_SUCCESS;
}
int main(int argc, char **argv)
{
SOCKETINFO si;
int ret;
// SSLWrap module initialisation.
if ( secinit() != SW_SUCCESS ) return SW_ERROR;
memset(&si, 0, sizeof(si));
strncpy(si.Host, "www.google.com", 10);
si.Port = 80;
if ( (ret = rawconnect(&si)) != SW_SUCCESS ) return SW_ERROR;
if ( (ret = rawclose(&si)) != SW_SUCCESS ) return SW_ERROR;
memset(&si, 0, sizeof(si));
strncpy(si.Host, "www.google.com", 10);
si.Port = 443;
if ( (ret = secconnect(&si)) != SW_SUCCESS ) return SW_ERROR;
if ( (ret = secclose(&si)) != SW_SUCCESS ) return SW_ERROR;
return 0;
}
Upvotes: 1
Views: 290
Reputation: 44250
strncpy(si.Host, "www.google.com", 10);
10 is too short; just use strcpy()
here.
[also a strong advice: never use strncpy() , at least until you know what it does ...]
why is strncpy() considered evil? Mostly because it is confusing, at least for novice users. How?
using strncpy(dst, src, siz);
:
(strlen(src) < siz)
, the restof the buffer will befilled with nullbytes(strlen(src) >= siz)
, no more than siz
bytes will be written to*dst
, but the copied string wil not be nul-terminated.The first case is not that important, a few cycles are wasted for writing the extra nulls. The second case can be disastrous if you expect the resulting string to be null-terminated. (most people do) This is why strncpy()
raises red flags.
How to avoid strncpy()
? There are a few ways. one of the simplest:
len = strlen(src);
if (len >=siz) len=siz-1;
memcpy(dst, src, len);
dst[len]= 0;
Upvotes: 1