src/server/util/socket.c

/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright 2026 Olaf Wintermann. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   1. Redistributions of source code must retain the above copyright
 *      notice, this list of conditions and the following disclaimer.
 *
 *   2. Redistributions in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include "socket.h"

#include <unistd.h>
#include <sys/fcntl.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

int util_server_socket_local(short *port) {
    int socket_fd = socket(AF_INET, SOCK_STREAM, 0);
    if(socket_fd < 0) {
        return -1;
    }
    
    short socket_port = 0;
    if(port) {
        socket_port = *port;
    }
    
    struct sockaddr_in addr;
    addr.sin_family = AF_INET;
    addr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
    addr.sin_port = htons(socket_port);
    
    if(bind(socket_fd, (struct sockaddr*)&addr, sizeof(addr))) {
        close(socket_fd);
        return -1;
    }
    
    socklen_t len = sizeof(addr);
    if(getsockname(socket_fd, (struct sockaddr *)&addr, &len) < 0) {
        close(socket_fd);
        return -1;
    }
    
    if(port) {
        *port = ntohs(addr.sin_port);
    }
    
    return socket_fd;
}

int util_socket_connect_local(short port) {
    int fd = socket(AF_INET, SOCK_STREAM, 0);
    if(fd < 0) {
        return -1;
    }
    
    struct sockaddr_in addr;
    addr.sin_family = AF_INET;
    addr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
    addr.sin_port = htons(port);
    
    if(connect(fd, (struct sockaddr*)&addr, sizeof(addr))) {
        close(fd);
        return -1;
    }
    
    return fd;
}

int util_socketpair(int fds[2]) {
    if (socketpair(AF_UNIX, SOCK_STREAM, 0, fds)) {
        fds[0] = -1;
        fds[1] = -1;
        return -1;
    }
    return 0;
}

int util_socket_setnonblock(int fd, int nonblock) {
    int flags;
    if ((flags = fcntl(fd, F_GETFL, 0)) == -1) {
        flags = 0;
    }
    if(nonblock) {
        flags |= O_NONBLOCK;
    } else {
        flags &= ~O_NONBLOCK;
    }
    if (fcntl(fd, F_SETFL, flags) != 0) {
        return 1;
    }
    return 0;
}