Network wrapper protocol as part of the practical master thesis
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/*
** Copyright (C) 2020 Johannes Kepler University Linz, Institute of Networks and Security
** Copyright (C) 2020 CDL Digidow <https://www.digidow.eu/>
**
** Licensed under the EUPL, Version 1.2 or – as soon they will be approved by
** the European Commission - subsequent versions of the EUPL (the "Licence").
** You may not use this work except in compliance with the Licence.
**
** You should have received a copy of the European Union Public License along
** with this program. If not, you may obtain a copy of the Licence at:
** <https://joinup.ec.europa.eu/software/page/eupl>
**
** Unless required by applicable law or agreed to in writing, software
** distributed under the Licence is distributed on an "AS IS" basis,
** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
** See the Licence for the specific language governing permissions and
** limitations under the Licence.
**
*/
#include "server.h"
int server_open(int16_t port) {
struct sockaddr_in servaddr;
int connfd = 0;
connfd = socket(AF_INET, SOCK_STREAM, 0);
if (-1 == connfd) {
printf("server_open: failed to create endpoint.\n");
return -1;
}
servaddr.sin_family = AF_INET;
servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
servaddr.sin_port = htons(port);
if (0 != bind(connfd, (const struct sockaddr *) &servaddr, sizeof(servaddr))) {
printf("server_open: failed to bind socket\n");
close(connfd);
return -1;
}
return connfd;
}
int server_start(conn_handler handler, int16_t port) {
struct sockaddr_in client;
unsigned int client_len = 0;
int connfd = 0;
int clientfd = 0;
int len = 0;
int ret = 0; //<0 .. failure, 0 .. continue, 1 .. exit, 2 .. shutdown
char buffer[MAX_BUFSIZE];
if(NULL == handler) {
printf("server_start: received empty handler, stopping\n");
return -1;
}
connfd = server_open(port);
if(-1 == connfd) {
printf("server_start: could not open port, stopping\n");
return -1;
}
if (0 != listen(connfd, MAX_CLIENTS)) {
printf("server_start: listen failed, stopping\n");
return -1;
}
printf("server_start: listening\n");
for(ret = 1; 1 == ret;) {
client_len = sizeof(client);
clientfd = accept(connfd, (struct sockaddr *) &client, &client_len);
if (0 >= clientfd) {
printf("server_start: connection to client failed\n");
ret = -1;
} else {
for(ret = 0; 0 == ret;) {
bzero(buffer, MAX_BUFSIZE);
len = 0;
do {
ret = read(clientfd, &buffer[len], sizeof(buffer)-len);
len += ret;
} while(0 < ret && buffer[len-1] != '\n');
if (0 > ret) {
printf("server_start: cannot read from socket\n");
ret = -1;
} else if(0 == ret) {
printf("server_start: client closed connection\n");
ret = 1;
} else {
ret = handler(buffer);
}
if (0 == ret && 0 >= write(clientfd, buffer, strlen(buffer))) {
printf("server_start: cannot write to socket\n");
ret = 1;
}
}
if (0 != close(clientfd)) {
printf("server_start: failed to close client connection properly\n");
ret = -1;
}
}
}
printf("server_start: closing connection\n");
if (0 != close(connfd)) {
printf("server_start: failed to close server port properly\n");
ret = -1;
}
return ret;
}