1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
|
\begin{verbatim}
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <string.h>
#include <unistd.h>
#include <gnutls/gnutls.h>
#define KEYFILE "key.pem"
#define CERTFILE "cert.pem"
#define CAFILE "ca.pem"
#define CRLFILE NULL
/* This is a sample TLS 1.0 echo server.
*/
#define SA struct sockaddr
#define SOCKET_ERR(err,s) if(err==-1) {perror(s);return(1);}
#define MAX_BUF 1024
#define PORT 5556 /* listen to 5556 port */
#define DH_BITS 1024
/* These are global */
gnutls_certificate_credentials x509_cred;
gnutls_session initialize_tls_session()
{
gnutls_session session;
gnutls_init(&session, GNUTLS_SERVER);
/* avoid calling all the priority functions, since the defaults
* are adequate.
*/
gnutls_set_default_priority( session);
gnutls_credentials_set(session, GNUTLS_CRD_CERTIFICATE, x509_cred);
/* request client certificate if any.
*/
gnutls_certificate_server_set_request( session, GNUTLS_CERT_REQUEST);
gnutls_dh_set_prime_bits( session, DH_BITS);
/* some broken clients may require this in order to connect.
* This may weaken security though.
*/
/* gnutls_handshake_set_rsa_pms_check( session, 1); */
return session;
}
gnutls_dh_params dh_params;
static int generate_dh_params(void) {
/* Generate Diffie Hellman parameters - for use with DHE
* kx algorithms. These should be discarded and regenerated
* once a day, once a week or once a month. Depends on the
* security requirements.
*/
gnutls_dh_params_init( &dh_params);
gnutls_dh_params_generate2( dh_params, DH_BITS);
return 0;
}
int main()
{
int err, listen_sd, i;
int sd, ret;
struct sockaddr_in sa_serv;
struct sockaddr_in sa_cli;
int client_len;
char topbuf[512];
gnutls_session session;
char buffer[MAX_BUF + 1];
int optval = 1;
char name[256];
strcpy(name, "Echo Server");
/* this must be called once in the program
*/
gnutls_global_init();
gnutls_certificate_allocate_credentials(&x509_cred);
gnutls_certificate_set_x509_trust_file(x509_cred, CAFILE,
GNUTLS_X509_FMT_PEM);
gnutls_certificate_set_x509_key_file(x509_cred, CERTFILE, KEYFILE,
GNUTLS_X509_FMT_PEM);
generate_dh_params();
gnutls_certificate_set_dh_params( x509_cred, dh_params);
/* Socket operations
*/
listen_sd = socket(AF_INET, SOCK_STREAM, 0);
SOCKET_ERR(listen_sd, "socket");
memset(&sa_serv, '\0', sizeof(sa_serv));
sa_serv.sin_family = AF_INET;
sa_serv.sin_addr.s_addr = INADDR_ANY;
sa_serv.sin_port = htons(PORT); /* Server Port number */
setsockopt(listen_sd, SOL_SOCKET, SO_REUSEADDR, &optval, sizeof(int));
err = bind(listen_sd, (SA *) & sa_serv, sizeof(sa_serv));
SOCKET_ERR(err, "bind");
err = listen(listen_sd, 1024);
SOCKET_ERR(err, "listen");
printf("%s ready. Listening to port '%d'.\n\n", name, PORT);
client_len = sizeof(sa_cli);
for (;;) {
session = initialize_tls_session();
sd = accept(listen_sd, (SA *) & sa_cli, &client_len);
printf("- connection from %s, port %d\n",
inet_ntop(AF_INET, &sa_cli.sin_addr, topbuf,
sizeof(topbuf)), ntohs(sa_cli.sin_port));
gnutls_transport_set_ptr( session, sd);
ret = gnutls_handshake( session);
if (ret < 0) {
close(sd);
gnutls_deinit(session);
fprintf(stderr, "*** Handshake has failed (%s)\n\n",
gnutls_strerror(ret));
continue;
}
printf("- Handshake was completed\n");
/* see the Getting peer's information example */
/* print_info(session); */
i = 0;
for (;;) {
bzero(buffer, MAX_BUF + 1);
ret = gnutls_record_recv( session, buffer, MAX_BUF);
if (ret == 0) {
printf
("\n- Peer has closed the GNUTLS connection\n");
break;
} else if (ret < 0) {
fprintf(stderr,
"\n*** Received corrupted data(%d). Closing the connection.\n\n",
ret);
break;
} else if (ret > 0) {
/* echo data back to the client
*/
gnutls_record_send( session, buffer,
strlen(buffer));
}
}
printf("\n");
gnutls_bye( session, GNUTLS_SHUT_WR); /* do not wait for
* the peer to close the connection.
*/
close(sd);
gnutls_deinit(session);
}
close(listen_sd);
gnutls_certificate_free_credentials(x509_cred);
gnutls_global_deinit();
return 0;
}
\end{verbatim}
|
