usock.c

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/*
 * usock - socket helper functions
 *
 * Copyright (C) 2010 Steven Barth <steven@midlink.org>
 * Copyright (C) 2011-2012 Felix Fietkau <nbd@openwrt.org>
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <netdb.h>
#include <poll.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <string.h>
#include <stdbool.h>
#include <stdio.h>
#include <poll.h>
 
#include "usock.h"
#include "utils.h"
 
static void usock_set_flags(int sock, unsigned int type)
{
        if (!(type & USOCK_NOCLOEXEC))
                fcntl(sock, F_SETFD, fcntl(sock, F_GETFD) | FD_CLOEXEC);
 
        if (type & USOCK_NONBLOCK)
                fcntl(sock, F_SETFL, fcntl(sock, F_GETFL) | O_NONBLOCK);
}
 
static int usock_connect(int type, struct sockaddr *sa, int sa_len, int family, int socktype, bool server)
{
        int sock;
 
        sock = socket(family, socktype, 0);
        if (sock < 0)
                return -1;
 
        usock_set_flags(sock, type);
 
        if (server) {
                const int one = 1;
                setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
 
                if (!bind(sock, sa, sa_len) &&
                    (socktype != SOCK_STREAM || !listen(sock, SOMAXCONN)))
                        return sock;
        } else {
                if (!connect(sock, sa, sa_len) || errno == EINPROGRESS)
                        return sock;
        }
 
        close(sock);
        return -1;
}
 
static int usock_unix(int type, const char *host)
{
        struct sockaddr_un sun = {.sun_family = AF_UNIX};
        bool server = !!(type & USOCK_SERVER);
        int socktype = ((type & 0xff) == USOCK_TCP) ? SOCK_STREAM : SOCK_DGRAM;
 
        if (strlen(host) >= sizeof(sun.sun_path)) {
                errno = EINVAL;
                return -1;
        }
        strcpy(sun.sun_path, host);
 
        return usock_connect(type, (struct sockaddr*)&sun, sizeof(sun), AF_UNIX, socktype, server);
}
 
static int
usock_inet_notimeout(int type, struct addrinfo *result, void *addr)
{
        struct addrinfo *rp;
        int socktype = ((type & 0xff) == USOCK_TCP) ? SOCK_STREAM : SOCK_DGRAM;
        bool server = !!(type & USOCK_SERVER);
        int sock;
 
        for (rp = result; rp != NULL; rp = rp->ai_next) {
                sock = usock_connect(type, rp->ai_addr, rp->ai_addrlen, rp->ai_family, socktype, server);
                if (sock >= 0) {
                        if (addr)
                                memcpy(addr, rp->ai_addr, rp->ai_addrlen);
                        return sock;
                }
        }
 
        return -1;
}
 
static int poll_restart(struct pollfd *fds, int nfds, int timeout)
{
        struct timespec ts, cur;
        int msec = timeout % 1000;
        int ret;
 
        clock_gettime(CLOCK_MONOTONIC, &ts);
 
        ts.tv_nsec += msec * 1000000;
        if (ts.tv_nsec > 1000000000) {
                ts.tv_sec++;
                ts.tv_nsec -= 1000000000;
        }
        ts.tv_sec += timeout / 1000;
 
        while (1) {
                ret = poll(fds, nfds, timeout);
                if (ret >= 0 || (errno != EINTR && errno != EAGAIN))
                        return ret;
 
                clock_gettime(CLOCK_MONOTONIC, &cur);
                timeout = (ts.tv_sec - cur.tv_sec) * 1000;
                timeout += (ts.tv_nsec - cur.tv_nsec) / 1000000;
                if (timeout <= 0)
                        return 0;
        }
}
 
int usock_inet_timeout(int type, const char *host, const char *service,
                       void *addr, int timeout)
{
        int socktype = ((type & 0xff) == USOCK_TCP) ? SOCK_STREAM : SOCK_DGRAM;
        bool server = !!(type & USOCK_SERVER);
        struct addrinfo *result, *rp;
        struct addrinfo hints = {
                .ai_family = (type & USOCK_IPV6ONLY) ? AF_INET6 :
                        (type & USOCK_IPV4ONLY) ? AF_INET : AF_UNSPEC,
                .ai_socktype = socktype,
                .ai_flags = AI_ADDRCONFIG
                        | ((type & USOCK_SERVER) ? AI_PASSIVE : 0)
                        | ((type & USOCK_NUMERIC) ? AI_NUMERICHOST : 0),
        };
        struct addrinfo *rp_v6 = NULL;
        struct addrinfo *rp_v4 = NULL;
        struct pollfd pfds[2] = {
            { .fd = -1, .events = POLLOUT },
            { .fd = -1, .events = POLLOUT },
        };
        int sock = -1;
        int i;
 
        if (getaddrinfo(host, service, &hints, &result))
                return -1;
 
        if (timeout <= 0 || server) {
                sock = usock_inet_notimeout(type, result, addr);
                goto free_addrinfo;
        }
 
        for (rp = result; rp != NULL; rp = rp->ai_next) {
                if (rp->ai_family == AF_INET6 && !rp_v6)
                        rp_v6 = rp;
                if (rp->ai_family == AF_INET && !rp_v4)
                        rp_v4 = rp;
        }
 
        if (!rp_v6 && !rp_v4)
                goto out;
 
        if (rp_v6) {
                rp = rp_v6;
                pfds[0].fd = usock_connect(type | USOCK_NONBLOCK, rp->ai_addr,
                                           rp->ai_addrlen, rp->ai_family,
                                           socktype, server);
                if (pfds[0].fd < 0) {
                        rp_v6 = NULL;
                        goto try_v4;
                }
 
                if (timeout > 300) {
                        if (poll_restart(pfds, 1, 300) == 1) {
                                rp = rp_v6;
                                sock = pfds[0].fd;
                                goto out;
                        }
                }
                timeout -= 300;
        }
 
try_v4:
        if (rp_v4) {
                rp = rp_v4;
                pfds[1].fd = usock_connect(type | USOCK_NONBLOCK, rp->ai_addr,
                                                 rp->ai_addrlen, rp->ai_family,
                                                 socktype, server);
                if (pfds[1].fd < 0) {
                        rp_v4 = NULL;
                        if (!rp_v6)
                                goto out;
                        goto wait;
                }
        }
 
wait:
        poll_restart(pfds + !rp_v6, !!rp_v6 + !!rp_v4, timeout);
        if (pfds[0].revents & POLLOUT) {
                rp = rp_v6;
                sock = pfds[0].fd;
                goto out;
        }
 
        if (pfds[1].revents & POLLOUT) {
                rp = rp_v4;
                sock = pfds[1].fd;
                goto out;
        }
 
out:
        for (i = 0; i < 2; i++) {
                int fd = pfds[i].fd;
                if (fd >= 0 && fd != sock)
                        close(fd);
        }
 
        if (!(type & USOCK_NONBLOCK))
                fcntl(sock, F_SETFL, fcntl(sock, F_GETFL) & ~O_NONBLOCK);
 
        if (addr && sock >= 0)
                memcpy(addr, rp->ai_addr, rp->ai_addrlen);
free_addrinfo:
        freeaddrinfo(result);
        return sock;
}
 
const char *usock_port(int port)
{
        static char buffer[sizeof("65535\0")];
 
        if (port < 0 || port > 65535)
                return NULL;
 
        snprintf(buffer, sizeof(buffer), "%u", port);
 
        return buffer;
}
 
int usock(int type, const char *host, const char *service) {
        int sock;
 
        if (type & USOCK_UNIX)
                sock = usock_unix(type, host);
        else
                sock = usock_inet(type, host, service, NULL);
 
        if (sock < 0)
                return -1;
 
        return sock;
}
 
int usock_wait_ready(int fd, int msecs) {
        struct pollfd fds[1];
        int res;
 
        fds[0].fd = fd;
        fds[0].events = POLLOUT;
 
        res = poll(fds, 1, msecs);
        if (res < 0) {
                return errno;
        } else if (res == 0) {
                return -ETIMEDOUT;
        } else {
                int err = 0;
                socklen_t optlen = sizeof(err);
 
                res = getsockopt(fd, SOL_SOCKET, SO_ERROR, &err, &optlen);
                if (res)
                        return errno;
                if (err)
                        return err;
        }
 
        return 0;
}