Sagui library v3.5.0
Cross-platform library which helps to develop web servers or frameworks.
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example_httpsrv_tls_cert_auth.c

Simple client-side certificate authentication using GnuTLS.

/* _
* ___ __ _ __ _ _ _(_)
* / __|/ _` |/ _` | | | | |
* \__ \ (_| | (_| | |_| | |
* |___/\__,_|\__, |\__,_|_|
* |___/
*
* Cross-platform library which helps to develop web servers or frameworks.
*
* Copyright (C) 2016-2019 Silvio Clecio <silvioprog@gmail.com>
*
* Sagui library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* Sagui library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with Sagui library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <stdlib.h>
#include <stdio.h>
#include <stdint.h>
#include <errno.h>
#include <gnutls/gnutls.h>
#include <gnutls/x509.h>
#include <sagui.h>
/* NOTE: Error checking has been omitted to make it clear. */
/*
* Simple example using TLS client authentication.
*
* Client example using cURL:
*
* curl -k --cert certs/client.p12 --pass abc123 --cert-type p12 https://localhost:<PORT>
*
* Certificate generation:
*
* ## CA
* certtool --generate-privkey --outfile ca.key
* echo 'cn = GnuTLS test CA' > ca.tmpl
* echo 'ca' >> ca.tmpl
* echo 'cert_signing_key' >> ca.tmpl
* echo 'expiration_days = 3650' >> ca.tmpl
* certtool --generate-self-signed --load-privkey ca.key --template ca.tmpl --outfile ca.pem
*
* ## Server
* certtool --generate-privkey --outfile server.key
* echo 'organization = GnuTLS test server' > server.tmpl
* echo 'cn = test.gnutls.org' >> server.tmpl
* echo 'tls_www_server' >> server.tmpl
* echo 'expiration_days = 3650' >> server.tmpl
* certtool --generate-certificate --load-ca-privkey ca.key --load-ca-certificate ca.pem --load-privkey server.key --template server.tmpl --outfile server.pem
*
* ## Client
* certtool --generate-privkey --outfile client.key
* echo 'cn = GnuTLS test client' > client.tmpl
* echo 'tls_www_client' >> client.tmpl
* echo 'expiration_days = 3650' >> client.tmpl
* certtool --generate-certificate --load-ca-certificate ca.pem --load-ca-privkey ca.key --load-privkey client.key --template client.tmpl --outfile client.pem
* certtool --to-p12 --p12-name=MyKey --password=abc123 --load-ca-certificate ca.pem --load-privkey client.key --load-certificate client.pem --outder --outfile client.p12
*/
#define KEY_FILE SG_EXAMPLES_CERTS_DIR "/server.key"
#define CERT_FILE SG_EXAMPLES_CERTS_DIR "/server.pem"
#define CA_FILE SG_EXAMPLES_CERTS_DIR "/ca.pem"
#define ERR_SIZE 256
#define PAGE_FMT \
"<html><head><title>Hello world</title></head><body><font " \
"color=\"%s\">%s</font></font></body></html>"
#define SECRET_MSG "Secret"
static void concat(char *s1, ...) {
va_list ap;
const char *s;
va_start(ap, s1);
while ((s = va_arg(ap, const char *)))
strcat(s1, s);
va_end(ap);
}
static bool sess_verify_cert(gnutls_session_t tls_session,
const char *line_break, char *err) {
gnutls_x509_crt_t cert = NULL;
const gnutls_datum_t *certs;
size_t len;
unsigned int status, certs_size;
int ret;
if (!tls_session || !line_break || !err) {
sg_strerror(EINVAL, err, ERR_SIZE);
return false;
}
if ((ret = gnutls_certificate_verify_peers2(tls_session, &status)) !=
GNUTLS_E_SUCCESS) {
concat(err, "Error verifying peers: ", gnutls_strerror(ret), line_break,
NULL);
goto error;
}
if (status & GNUTLS_CERT_INVALID)
concat(err, "The certificate is not trusted", line_break, NULL);
if (status & GNUTLS_CERT_SIGNER_NOT_FOUND)
concat(err, "The certificate has not got a known issuer", line_break, NULL);
if (status & GNUTLS_CERT_REVOKED)
concat(err, "The certificate has been revoked", line_break, NULL);
if (gnutls_certificate_type_get(tls_session) != GNUTLS_CRT_X509) {
concat(err, "The certificate type is not X.509", line_break, NULL);
goto error;
}
if ((ret = gnutls_x509_crt_init(&cert)) != GNUTLS_E_SUCCESS) {
concat(err,
"Error in the certificate initialization: ", gnutls_strerror(ret),
line_break, NULL);
goto error;
}
if (!(certs = gnutls_certificate_get_peers(tls_session, &certs_size))) {
concat(err, "No certificate was found", line_break, NULL);
goto error;
}
if ((ret = gnutls_x509_crt_import(cert, &certs[0], GNUTLS_X509_FMT_DER)) !=
GNUTLS_E_SUCCESS) {
concat(err, "Error parsing certificate: ", gnutls_strerror(ret), line_break,
NULL);
goto error;
}
if (gnutls_x509_crt_get_expiration_time(cert) < time(NULL)) {
concat(err, "The certificate has expired", line_break, NULL);
goto error;
}
if (gnutls_x509_crt_get_activation_time(cert) > time(NULL)) {
concat(err, "The certificate has not been activated yet", line_break, NULL);
goto error;
}
error:
len = strlen(err);
err[len - strlen("<br>")] = '\0';
gnutls_x509_crt_deinit(cert);
return len == 0;
}
static void req_cb(__SG_UNUSED void *cls, struct sg_httpreq *req,
struct sg_httpres *res) {
char msg[ERR_SIZE];
char *color, *page;
size_t page_size;
unsigned int status;
if (sess_verify_cert(sg_httpreq_tls_session(req), "<br>", msg)) {
strcpy(msg, SECRET_MSG);
color = "green";
status = 200;
} else {
color = "red";
status = 500;
}
page_size = (size_t) snprintf(NULL, 0, PAGE_FMT, color, msg);
page = sg_alloc(page_size);
snprintf(page, page_size, PAGE_FMT, color, msg);
sg_httpres_send(res, page, "text/html; charset=utf-8", status);
sg_free(page);
}
int main(int argc, const char *argv[]) {
struct sg_httpsrv *srv;
gnutls_datum_t key_file, cert_file, ca_file;
int ret, status;
uint16_t port;
if (argc != 2) {
printf("%s <PORT>\n", argv[0]);
return EXIT_FAILURE;
}
port = strtol(argv[1], NULL, 10);
status = EXIT_FAILURE;
srv = sg_httpsrv_new(req_cb, NULL);
memset(&key_file, 0, sizeof(gnutls_datum_t));
memset(&cert_file, 0, sizeof(gnutls_datum_t));
memset(&ca_file, 0, sizeof(gnutls_datum_t));
if ((ret = gnutls_load_file(KEY_FILE, &key_file)) != GNUTLS_E_SUCCESS) {
fprintf(stderr, "Error loading the private key \"%s\": %s\n", KEY_FILE,
gnutls_strerror(ret));
fflush(stdout);
goto error;
}
if ((ret = gnutls_load_file(CERT_FILE, &cert_file)) != GNUTLS_E_SUCCESS) {
fprintf(stderr, "Error loading the certificate \"%s\": %s\n", CERT_FILE,
gnutls_strerror(ret));
fflush(stdout);
goto error;
}
if ((ret = gnutls_load_file(CA_FILE, &ca_file)) != GNUTLS_E_SUCCESS) {
fprintf(stderr, "Error loading the CA \"%s\": %s\n", CA_FILE,
gnutls_strerror(ret));
fflush(stdout);
goto error;
}
if (sg_httpsrv_tls_listen2(srv, (const char *) key_file.data, NULL,
(const char *) cert_file.data,
(const char *) ca_file.data, NULL, port, false)) {
status = EXIT_SUCCESS;
fprintf(stdout, "Server running at https://localhost:%d\n",
sg_httpsrv_port(srv));
fflush(stdout);
getchar();
}
error:
sg_httpsrv_free(srv);
if (key_file.size > 0)
gnutls_free(key_file.data);
if (cert_file.size > 0)
gnutls_free(cert_file.data);
if (ca_file.size > 0)
gnutls_free(ca_file.data);
return status;
}
sg_httpsrv_tls_listen2
bool sg_httpsrv_tls_listen2(struct sg_httpsrv *srv, const char *key, const char *pwd, const char *cert, const char *trust, const char *dhparams, uint16_t port, bool threaded)
sg_httpsrv_new
struct sg_httpsrv * sg_httpsrv_new(sg_httpreq_cb cb, void *cls) __attribute__((malloc))
sg_httpreq_tls_session
void * sg_httpreq_tls_session(struct sg_httpreq *req)
sg_httpsrv_free
void sg_httpsrv_free(struct sg_httpsrv *srv)
sg_httpres_send
#define sg_httpres_send(res, val, content_type, status)
Definition sagui.h:1032
sg_httpsrv_port
uint16_t sg_httpsrv_port(struct sg_httpsrv *srv)
sg_alloc
void * sg_alloc(size_t size) __attribute__((malloc))
sg_strerror
char * sg_strerror(int errnum, char *errmsg, size_t errlen)
sg_free
void sg_free(void *ptr)
sg_httpreq
sg_httpres
sg_httpsrv
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