336 lines
11 KiB
C
336 lines
11 KiB
C
/* client-dtls-callback.c
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*
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* Copyright (C) 2006-2020 wolfSSL Inc.
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*
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* This file is part of wolfSSL. (formerly known as CyaSSL)
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*
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* wolfSSL is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* wolfSSL is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
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*
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*=============================================================================
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*
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* Bare-bones example of a DTLS client for instructional/learning purposes.
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* Utilizes DTLS 1.2 and custom IO callbacks.
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*/
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#ifndef WOLFSSL_USER_SETTINGS
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#include <wolfssl/options.h>
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#endif
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#include <wolfssl/wolfcrypt/settings.h>
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#include <wolfssl/ssl.h>
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#include <stdio.h> /* standard in/out procedures */
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#include <stdlib.h> /* defines system calls */
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#include <string.h> /* necessary for memset */
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#include <netdb.h>
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#include <sys/socket.h> /* used for all socket calls */
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#include <netinet/in.h> /* used for sockaddr_in */
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#include <arpa/inet.h>
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#include <errno.h>
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#include <signal.h>
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#include <unistd.h>
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#define SERV_PORT 11111 /* define our server port number */
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#define MSGLEN 4096
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#define DTLS_MTU 1500
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static int cleanup = 0; /* To handle shutdown */
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static void sig_handler(const int sig)
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{
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printf("\nSIGINT %d handled\n", sig);
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cleanup = 1;
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return;
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}
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typedef struct SharedDtls {
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WOLFSSL* ssl; /* WOLFSSL object being shared */
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int sd; /* socket fd */
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struct sockaddr_in servAddr; /* server sockaddr */
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socklen_t servSz; /* length of servAddr */
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} SharedDtls;
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int my_IORecv(WOLFSSL* ssl, char* buff, int sz, void* ctx)
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{
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SharedDtls* shared = (SharedDtls*)ctx;
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int recvd;
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struct sockaddr addr;
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socklen_t addrSz = sizeof(addr);
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int dtls_timeout;
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printf("my_IORecv fd %d, buf %d\n", shared->sd, sz);
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/* Get current DTLS handshake timeout. */
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dtls_timeout = wolfSSL_dtls_get_current_timeout(ssl);
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printf("my_IORecv timeout %d\n", dtls_timeout);
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/* If we are performing the DTLS handshake, and we are in blocking mode, we
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* set a socket timeout at OS level. */
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if (!wolfSSL_is_init_finished(ssl)) {
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/* Still in handshake: set the OS timeout */
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if (dtls_timeout > 0) {
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struct timeval tv;
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tv.tv_sec = dtls_timeout;
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tv.tv_usec = 0;
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if (setsockopt(shared->sd, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv)) < 0) {
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fprintf(stderr, "setsockopt failed\n");
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return WOLFSSL_CBIO_ERR_GENERAL;
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}
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}
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} else {
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struct timeval tv = {0, 0};
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if (setsockopt(shared->sd, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv)) < 0) {
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fprintf(stderr, "setsockopt failed\n");
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return WOLFSSL_CBIO_ERR_GENERAL;
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}
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}
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/* Receive datagram */
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recvd = recvfrom(shared->sd, buff, sz, 0, &addr, &addrSz);
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if (recvd == -1) {
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/* error encountered. Be responsible and report it in wolfSSL terms */
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fprintf(stderr, "IO RECEIVE ERROR: %d\n", errno);
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switch (errno) {
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#if EAGAIN != EWOULDBLOCK
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case EAGAIN: /* EAGAIN == EWOULDBLOCK on some systems, but not others */
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#endif
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case EWOULDBLOCK:
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if (!wolfSSL_dtls(ssl) || wolfSSL_get_using_nonblock(ssl)) {
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fprintf(stderr, "would block\n");
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return WOLFSSL_CBIO_ERR_WANT_READ;
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}
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else {
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fprintf(stderr, "socket timeout\n");
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return WOLFSSL_CBIO_ERR_TIMEOUT;
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}
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case ECONNRESET:
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fprintf(stderr, "connection reset\n");
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return WOLFSSL_CBIO_ERR_CONN_RST;
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case EINTR:
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fprintf(stderr, "socket interrupted\n");
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cleanup = 1;
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return WOLFSSL_CBIO_ERR_GENERAL;
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/* NOTE: Don't return WOLFSSL_CBIO_ERR_ISR. It keeps trying to recv */
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case ECONNREFUSED:
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fprintf(stderr, "connection refused\n");
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return WOLFSSL_CBIO_ERR_WANT_READ;
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case ECONNABORTED:
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fprintf(stderr, "connection aborted\n");
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return WOLFSSL_CBIO_ERR_CONN_CLOSE;
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default:
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fprintf(stderr, "general error\n");
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return WOLFSSL_CBIO_ERR_GENERAL;
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}
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}
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else if (recvd == 0) {
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printf("Connection closed\n");
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return WOLFSSL_CBIO_ERR_CONN_CLOSE;
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}
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/* successful receive */
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printf("my_IORecv: received %d bytes from %d\n", recvd, shared->sd);
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return recvd;
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}
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int my_IOSend(WOLFSSL* ssl, char* buff, int sz, void* ctx)
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{
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SharedDtls* shared = (SharedDtls*)ctx;
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int sent;
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const struct sockaddr* addr = NULL;
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socklen_t addrSz = 0;
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if (shared) {
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addr = (const struct sockaddr*)&shared->servAddr;
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addrSz = shared->servSz;
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}
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printf("my_IOSend fd %d, buf %d\n", shared->sd, sz);
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/* Send datagram */
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sent = sendto(shared->sd, buff, sz, 0, addr, addrSz);
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if (sent == -1) {
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/* error encountered. Be responsible and report it in wolfSSL terms */
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fprintf(stderr, "IO SEND ERROR: %d\n", errno);
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switch (errno) {
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#if EAGAIN != EWOULDBLOCK
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case EAGAIN: /* EAGAIN == EWOULDBLOCK on some systems, but not others */
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#endif
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case EWOULDBLOCK:
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fprintf(stderr, "would block\n");
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return WOLFSSL_CBIO_ERR_WANT_READ;
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case ECONNRESET:
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fprintf(stderr, "connection reset\n");
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return WOLFSSL_CBIO_ERR_CONN_RST;
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case EINTR:
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fprintf(stderr, "socket interrupted\n");
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cleanup = 1;
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return WOLFSSL_CBIO_ERR_GENERAL;
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/* NOTE: Don't return WOLFSSL_CBIO_ERR_ISR. It keeps trying to send */
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case EPIPE:
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fprintf(stderr, "socket EPIPE\n");
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return WOLFSSL_CBIO_ERR_CONN_CLOSE;
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default:
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fprintf(stderr, "general error\n");
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return WOLFSSL_CBIO_ERR_GENERAL;
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}
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}
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else if (sent == 0) {
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printf("Connection closed\n");
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return 0;
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}
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/* successful send */
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printf("my_IOSend: sent %d bytes to %d\n", sent, shared->sd);
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return sent;
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}
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int main (int argc, char** argv)
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{
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/* standard variables used in a dtls client */
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int ret = 0, err;
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int sockfd = -1;
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WOLFSSL* ssl = NULL;
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WOLFSSL_CTX* ctx = NULL;
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const char* ca_cert = "../certs/ca-cert.pem";
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char buff[MSGLEN];
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int buffLen;
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SharedDtls shared;
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/* Program argument checking */
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if (argc != 2) {
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printf("usage: udpcli <IP address>\n");
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return 1;
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}
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/* Code for handling signals */
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struct sigaction act, oact;
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act.sa_handler = sig_handler;
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sigemptyset(&act.sa_mask);
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act.sa_flags = 0;
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sigaction(SIGINT, &act, &oact);
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wolfSSL_Debugging_ON();
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/* Initialize wolfSSL before assigning ctx */
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wolfSSL_Init();
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if ( (ctx = wolfSSL_CTX_new(wolfDTLSv1_2_client_method())) == NULL) {
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fprintf(stderr, "wolfSSL_CTX_new error.\n");
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goto exit;
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}
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/* Register callbacks */
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wolfSSL_CTX_SetIORecv(ctx, my_IORecv);
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wolfSSL_CTX_SetIOSend(ctx, my_IOSend);
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/* Load CA certificates into ctx variable */
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if (wolfSSL_CTX_load_verify_locations(ctx, ca_cert, 0)
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!= SSL_SUCCESS) {
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fprintf(stderr, "Error loading %s, please check the file.\n", ca_cert);
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goto exit;
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}
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/* Assign ssl variable */
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ssl = wolfSSL_new(ctx);
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if (ssl == NULL) {
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printf("unable to get ssl object");
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goto exit;
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}
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memset(&shared, 0, sizeof(shared));
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shared.ssl = ssl;
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/* servAddr setup */
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shared.servSz = sizeof(shared.servAddr);
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shared.servAddr.sin_family = AF_INET;
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shared.servAddr.sin_port = htons(SERV_PORT);
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if (inet_pton(AF_INET, argv[1], &shared.servAddr.sin_addr) < 1) {
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printf("Error and/or invalid IP address");
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goto exit;
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}
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if ( (sockfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
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printf("cannot create a socket.");
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goto exit;
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}
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shared.sd = sockfd;
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wolfSSL_SetIOWriteCtx(ssl, &shared);
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wolfSSL_SetIOReadCtx(ssl, &shared);
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if (wolfSSL_connect(ssl) != SSL_SUCCESS) {
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err = wolfSSL_get_error(ssl, 0);
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printf("err = %d, %s\n", err, wolfSSL_ERR_reason_error_string(err));
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printf("SSL_connect failed\n");
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goto exit;
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}
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/**************************************************************************/
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/* Code for sending datagram to server */
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if (fgets(buff, sizeof(buff), stdin) != NULL) {
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/* Send buffer to the server */
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buffLen = strlen(buff);
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if (( wolfSSL_write(ssl, buff, buffLen)) != buffLen) {
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err = wolfSSL_get_error(ssl, 0);
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if (err != SSL_ERROR_WANT_WRITE) {
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printf("err = %d, %s\n", err, wolfSSL_ERR_reason_error_string(err));
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printf("SSL_write failed\n");
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goto exit;
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}
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}
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/* Receive message from server */
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ret = wolfSSL_read(ssl, buff, sizeof(buff)-1);
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if (ret < 0) {
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err = wolfSSL_get_error(ssl, 0);
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if (err != SSL_ERROR_WANT_READ) {
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printf("err = %d, %s\n", err, wolfSSL_ERR_reason_error_string(err));
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printf("SSL_read failed\n");
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goto exit;
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}
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}
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buffLen = ret;
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ret = 0;
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/* Add a terminating character to the generic server message */
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buff[buffLen] = '\0';
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fputs(buff, stdout);
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}
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/* End code for sending datagram to server */
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/**************************************************************************/
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exit:
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/* Housekeeping */
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if (ssl) {
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wolfSSL_shutdown(ssl);
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wolfSSL_free(ssl);
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}
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if (sockfd != -1) {
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close(sockfd);
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}
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if (ctx) {
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wolfSSL_CTX_free(ctx);
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}
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wolfSSL_Cleanup();
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return ret;
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}
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