SSL socket snippet, server checks client's certificates

SSL_Socket_snippet/sslsock.c

@@ -0,0 +1,184 @@
+/*
+ * This file is part of the sslsosk project.
+ * Copyright 2023 Edward V. Emelianov <edward.emelianoff@gmail.com>.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <pthread.h>
+#include <resolv.h>
+#include <signal.h>     // pthread_kill
+#include <stdio.h>
+#include <string.h>
+#include <usefull_macros.h>
+
+#include "cmdlnopts.h"
+#include "sslsock.h"
+#ifdef SERVER
+#include "server.h"
+#else
+#include "client.h"
+#endif
+
+#ifdef SERVER
+static int OpenConn(int port){
+    int sd = socket(PF_INET, SOCK_STREAM, 0);
+    if(sd < 0){
+        LOGERR("Can't open socket");
+        ERRX("socket()");
+    }
+    int enable = 1;
+    // allow reuse of descriptor
+    if(setsockopt(sd, SOL_SOCKET,  SO_REUSEADDR, (void *)&enable, sizeof(int)) < 0){
+        LOGERR("Can't apply SO_REUSEADDR to socket");
+        ERRX("setsockopt()");
+    }
+    struct sockaddr_in addr = {0};
+    addr.sin_family = AF_INET;
+    addr.sin_port = htons(port);
+    addr.sin_addr.s_addr = INADDR_ANY;
+    if(bind(sd, (struct sockaddr*)&addr, sizeof(addr))){
+        LOGWARN("Can't bind port %d", port);
+        ERRX("bind()");
+    }
+    if(listen(sd, BACKLOG)){
+        LOGWARN("Can't listen()");
+        ERRX("listen()");
+    }
+    return sd;
+}
+#else
+static int OpenConn(int port){
+    FNAME();
+    int sd;
+    struct hostent *host;
+    struct sockaddr_in addr;
+    if((host = gethostbyname(G.serverhost)) == NULL ){
+        LOGWARN("gethostbyname(%s) error", G.serverhost);
+        ERRX("gethostbyname()");
+    }
+    sd = socket(PF_INET, SOCK_STREAM, 0);
+    DBG("sd=%d", sd);
+    bzero(&addr, sizeof(addr));
+    addr.sin_family = AF_INET;
+    addr.sin_port = htons(port);
+    addr.sin_addr.s_addr = *(long*)(host->h_addr);
+    if(connect(sd, (struct sockaddr*)&addr, sizeof(addr))){
+        close(sd);
+        LOGWARN("Can't connect to %s", G.serverhost);
+        ERRX("connect()");
+    }
+    return sd;
+}
+#endif
+
+static SSL_CTX* InitCTX(void){
+    const SSL_METHOD *method;
+    SSL_CTX *ctx;
+    OpenSSL_add_all_algorithms();
+    SSL_load_error_strings();
+    method =
+#ifdef CLIENT
+      TLS_client_method();
+#else
+      TLS_server_method();
+#endif
+    ctx = SSL_CTX_new(method);
+    if(!ctx){
+        LOGWARN("Can't create SSL context");
+        ERRX("SSL_CTX_new()");
+    }
+    if(SSL_CTX_load_verify_locations(ctx, G.ca, NULL) != 1){
+        LOGWARN("Could not set the CA file location\n");
+        ERRX("Could not set the CA file location\n");
+    }
+#ifdef SERVER
+
+    SSL_CTX_set_client_CA_list(ctx, SSL_load_client_CA_file(G.ca));
+#endif
+    if(SSL_CTX_use_certificate_file(ctx, G.cert, SSL_FILETYPE_PEM) <= 0){
+        LOGWARN("Can't use SSL certificate %s", G.cert);
+        ERRX("Can't use SSL certificate %s", G.cert);
+    }
+    if(SSL_CTX_use_PrivateKey_file(ctx, G.key, SSL_FILETYPE_PEM) <= 0){
+        LOGWARN("Can't use SSL key %s", G.key);
+        ERRX("Can't use SSL key %s", G.key);
+    }
+    if(!SSL_CTX_check_private_key(ctx)){
+        LOGWARN("Private key does not match the public certificate\n");
+        ERRX("Private key does not match the public certificate\n");
+    }
+    SSL_CTX_set_mode(ctx, SSL_MODE_AUTO_RETRY);
+#ifdef SERVER
+    SSL_CTX_set_verify(ctx, // Specify that we need to verify the client as well
+       SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT,
+       NULL);
+#else
+    SSL_CTX_set_verify(ctx, SSL_VERIFY_PEER, NULL);
+#endif
+    SSL_CTX_set_verify_depth(ctx, 1); // We accept only certificates signed only by the CA himself
+    return ctx;
+}
+
+int open_socket(){
+    int fd;
+    SSL_library_init();
+    SSL_CTX *ctx = InitCTX();
+    fd = OpenConn(atoi(G.port));
+#ifdef SERVER
+    serverproc(ctx, fd);
+#else
+    clientproc(ctx, fd);
+#endif
+    // newer reached
+    close(fd);
+    SSL_CTX_free(ctx);
+    return 0;
+}
+
+static int geterrcode(SSL *ssl, int errcode){
+    int sslerr = SSL_get_error(ssl, errcode);
+    if(SSL_ERROR_WANT_READ == sslerr ||
+        SSL_ERROR_WANT_WRITE == sslerr) return 0; // empty call
+    int sd = SSL_get_fd(ssl);
+    LOGERR("SSL error %d @client %d", sslerr, sd);
+    WARNX("SSL error %d @client %d", sslerr, sd);
+    return -1;
+}
+
+/**
+ * @brief read_string - read '\n'-terminated string from SSL
+ * @param ssl - SSL
+ * @param buf - buffer for text
+ * @param l - max buf length (including zero)
+ * @return amount of bytes read or -1 if client disconnected
+ */
+int read_string(SSL *ssl, char *buf, int l){
+    if(!ssl || l < 1) return 0;
+    int bytes = SSL_peek(ssl, buf, l);
+//    DBG("Peek: %d (bufsz %d); buf=%s", bytes, l, buf);
+    if(bytes < 1){ // nothing to read or error
+        return geterrcode(ssl, bytes);
+    }
+    if(bytes < l && buf[bytes-1] != '\n'){ // string not ready, no buffer overfull
+        return 0; // wait a rest of string
+    }
+    bytes = SSL_read(ssl, buf, l);
+//    DBG("Read: %d", bytes);
+    if(bytes < 1){ // error
+        return geterrcode(ssl, bytes);
+    }
+    buf[bytes-1] = 0; // replace '\n' with 0
+    return bytes;
+}