Example web server using SSL connection. It will always send the same web. It's just a test to stablish a secure connection and send some data This server cannot attend simultaneous connections. More...

#include <fcntl.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>
#include <stdio.h>
#include <netinet/in.h>
#include <resolv.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <openssl/rand.h>
#include <openssl/ssl.h>
#include <openssl/err.h>

Classes
struct	Sslc

Macros
#define	PORT 1430

#define	BUFFERSIZE 16384

#define	CRLF "\r\n"

#define	RESPONSE

#define	CERTFILE "sslserverchain.pem"

#define	KEYFILE "sslserver.key"

Functions
int	TCP_Server (Sslc *h, int port)

int	TCP_select (Sslc *h, double timeout)

int	SSL_init (Sslc *h)

int	SSL_load_certificates (Sslc h, char cert, char *key)

int	TCP_acceptClient (Sslc *h)

int	TCP_clientDialog (Sslc *h)

int	SSL_clientDialog (Sslc *h)

void	panic (char *msg)

void	aclock (int loop)

int	main (int argv, char **argc)

Detailed Description

Example web server using SSL connection. It will always send the same web. It's just a test to stablish a secure connection and send some data This server cannot attend simultaneous connections.

Author: Gaspar Fernández blake.nosp@m.yed@.nosp@m.totak.nosp@m.i.co.nosp@m.m

Version: 0.1

Date: 18 apr 2015

Changelog: 20150422 - Some more doc.

To compile $ gcc -o serverssl serverssl.c -lcrypto -lssl

Definition in file serverssl.c.

Macro Definition Documentation

#define BUFFERSIZE 16384

Buffer Size to use

Definition at line 42 of file serverssl.c.

Referenced by SSL_clientDialog(), and TCP_clientDialog().

#define CERTFILE "sslserverchain.pem"

Certificate file, or certificate chain file

Definition at line 55 of file serverssl.c.

#define CRLF "\r\n"

CRLF

Definition at line 45 of file serverssl.c.

#define KEYFILE "sslserver.key"

Key file

Definition at line 57 of file serverssl.c.

#define PORT 1430

Port

Definition at line 39 of file serverssl.c.

#define RESPONSE

Value:

"HTTP/1.1 200 OK" CRLF      \
  "Content-Type: text/html charset=utf-8" CRLF  \
  "Server: ServerTest" CRLF			\
  CRLF                      \
  "<html><head><title>Server Test</title></head><body>This is just a test</body></html>" CRLF

The only response of this server

Definition at line 48 of file serverssl.c.

Referenced by SSL_clientDialog(), and TCP_clientDialog().

Function Documentation

void aclock ( int loop )

ASCII clock to wait for clients

Parameters

loop	Just a number, when it changes, it draws a new character. If loop == 0, restarts

Returns: void

Definition at line 339 of file serverssl.c.

 {
   if (loop==0)
     printf("[SERVER] Waiting for connections  ");
 
   printf("\033[1D");        /* ANSI code to go back 2 characters */
   switch (loop%4)
     {
     case 0: printf("|"); break;
     case 1: printf("/"); break;
     case 2: printf("-"); break;
     case 3: printf("\\"); break;
     default:            /* Nothing here */
       break;
     }
 
   fflush(stdout);       /* Update screen */
 }

void panic ( char * msg )

Prints a tragic error and exit

Parameters

msg	Error text

Returns: void

Definition at line 359 of file serverssl.c.

 {
   fprintf (stderr, "Error: %s (errno %d, %s)\n", msg, errno, strerror(errno));
   /* Print SSL errors */
   ERR_print_errors_fp(stderr);
   exit(2);
 }

int SSL_clientDialog ( Sslc * h )

It's everything we're here for. SSL dialog with the clients

Parameters

h	Our struct

Returns: 0 if OK

Definition at line 274 of file serverssl.c.

References BUFFERSIZE, Sslc::client_skt, Sslc::ctx, RESPONSE, and Sslc::ssl.

Referenced by TCP_acceptClient().

 {
   char buffer[BUFFERSIZE];
   int bytecount;
 
   h->ssl = SSL_new(h->ctx);
   if (h->ssl == NULL)
     return -11;
   /* SSL_set_options(h->ssl, SSL_OP_ALL ); */
 
   if (SSL_set_fd(h->ssl, h->client_skt) == 0)
     return -12;
 
   /* Accept SSL connection and handshake */
   if (SSL_accept(h->ssl) < 1)
     return -13;
 
   memset(buffer, 0, BUFFERSIZE);
   if((bytecount = SSL_read(h->ssl, buffer, BUFFERSIZE)) < 1)
     return -7;
 
   if (SSL_write(h->ssl, RESPONSE, strlen(RESPONSE))< 1)
     return -8;
 
   SSL_free(h->ssl);     /* free mem */
 
   return 0;
 }

int SSL_init ( Sslc * h )

Initializes SSL connection and creates the SSL Context

Parameters

h	Our struct to store everything

Returns: 0 if OK

Definition at line 303 of file serverssl.c.

References Sslc::ctx.

 {
   SSL_library_init();       /* not reentrant! */
 
   SSL_load_error_strings();
 
   OpenSSL_add_all_algorithms();     /* load & register all cryptos, etc. */
 
   /* We can try SSLv23_server_method() to try several 
    methods, starting from the more secure*/
   h->ctx = SSL_CTX_new(TLSv1_2_server_method());
   if (h->ctx == NULL)
     return -4;
 
   return 0;
 }

int SSL_load_certificates	(	Sslc *	h,
		char *	cert,
		char *	key
	)

Loads certificates in the context.

Parameters

h	Our struct to store everything
cert	PEM certificate file or chain (we can store several certificates in one file, just concatenating them.
key	Encryption key

Returns: 0 if OK

Definition at line 320 of file serverssl.c.

References Sslc::ctx.

 {
   if ( SSL_CTX_use_certificate_chain_file(h->ctx, cert) < 1 )
       return -8;
 
   /* set the private key */
   if ( SSL_CTX_use_PrivateKey_file(h->ctx, key, SSL_FILETYPE_PEM) <= 0 )
     return -9;
 
   /* verify private key */
   if ( !SSL_CTX_check_private_key(h->ctx) )
     {
       printf("Private key doesn't match the public certificate\n");
       return -10;
     }
 
   return 0;
 }

int TCP_acceptClient ( Sslc * h )

Accepts client and start dialog

Parameters

h	Our struct

Returns: 0 if OK

Definition at line 238 of file serverssl.c.

References Sslc::client_skt, Sslc::skt, and SSL_clientDialog().

 {
   struct sockaddr_in client_addr;
   socklen_t size_addr = sizeof(struct sockaddr_in);
 
   if ((h->client_skt = accept( h->skt, (struct sockaddr*)&client_addr, &size_addr))!= -1)
     {
       printf("\nNew client connection from %s:%d\n", inet_ntoa(client_addr.sin_addr), client_addr.sin_port);
       int r = SSL_clientDialog(h);
       if (r<0)
     {
       printf ("There was a problem with this client connection\n");
       ERR_print_errors_fp(stderr);
     }
       close(h->client_skt);
     }
 
   /* Returns 0 to avoid tragic fails, just display on screen*/
   return -6;
 }

int TCP_clientDialog ( Sslc * h )

Just a test, replace SSL_clientDialog() in acceptClient() by TCP_clientDialog() to create an insecure web server.

Parameters

h	Our struct

Returns: 0 if OK

Definition at line 259 of file serverssl.c.

References BUFFERSIZE, Sslc::client_skt, and RESPONSE.

 {
   char buffer[BUFFERSIZE];
   int bytecount;
 
   memset(buffer, 0, BUFFERSIZE);
   if((bytecount = recv(h->client_skt, buffer, BUFFERSIZE, 0))== -1)
     return -7;
 
   if (send(h->client_skt, RESPONSE, strlen(RESPONSE), 0)<0)
     return -8;
 
   return 0;
 }

int TCP_select	(	Sslc *	h,
		double	timeout
	)

Uses select to test if there is anything waiting to be read. The same function as myssl.c

Parameters

h	Our structure. Only the socket will be used
timeout	Timeout before giving up

Returns: (0 timeout, 1 data waiting, <0 fail)

Definition at line 222 of file serverssl.c.

References Sslc::skt.

 {
   fd_set fds;
   FD_ZERO(&fds);
   FD_SET(h->skt, &fds);
   fd_set *rset=&fds;
   fd_set *wset=NULL;
 
   struct timeval tv;
   tv.tv_sec = (int)(timeout);
   tv.tv_usec = (int)((timeout - (int)(timeout)) * 1000000.0);
 
   int ret = select(h->skt+1, rset, wset, NULL, &tv);
   return ret;
 }

int TCP_Server	(	Sslc *	h,
		int	port
	)

Parameters

h	Our struct
port	Por to listen to

Returns: (0 if OK, else fail)

Definition at line 201 of file serverssl.c.

References Sslc::skt.

 {
   struct sockaddr_in my_addr;
 
   h->skt = socket(AF_INET, SOCK_STREAM, 0);
   if(h->skt < 0)
     return -1;
 
   my_addr.sin_family = AF_INET ;
   my_addr.sin_port = htons(port);
   my_addr.sin_addr.s_addr = INADDR_ANY ;
 
   if( bind( h->skt, (struct sockaddr*)&my_addr, sizeof(my_addr)) == -1 )
     return -2;
 
   if(listen( h->skt, 10) == -1 )
     return -3;
 
   return 0;
 }

Communication Samples

Some C code examples

Classes

Macros

Functions

Detailed Description

Macro Definition Documentation

Function Documentation