socket.c

/*
 * Copyright (c) 1995 Danny Gasparovski.
 *
 * Please read the file COPYRIGHT for the
 * terms and conditions of the copyright.
 */

#include "qemu-common.h"
#include <slirp.h>
#include "ip_icmp.h"
#ifdef __sun__
#include <sys/filio.h>
#endif

static void sofcantrcvmore(struct socket *so);
static void sofcantsendmore(struct socket *so);

struct socket *solookup(struct socket *head, struct in_addr laddr, u_int lport,
                        struct in_addr faddr, u_int fport)
{
    struct socket *so;

    for (so = head->so_next; so != head; so = so->so_next) {
        if (so->so_lport == lport && so->so_laddr.s_addr == laddr.s_addr &&
            so->so_faddr.s_addr == faddr.s_addr && so->so_fport == fport)
            break;
    }

    if (so == head)
        return (struct socket *)NULL;
    return so;
}

/*
 * Create a new socket, initialise the fields
 * It is the responsibility of the caller to
 * insque() it into the correct linked-list
 */
struct socket *socreate(Slirp *slirp)
{
    struct socket *so;

    so = (struct socket *)malloc(sizeof(struct socket));
    if (so) {
        memset(so, 0, sizeof(struct socket));
        so->so_state = SS_NOFDREF;
        so->s = -1;
        so->slirp = slirp;
        so->pollfds_idx = -1;
    }
    return (so);
}

/*
 * remque and free a socket, clobber cache
 */
void sofree(struct socket *so)
{
    Slirp *slirp = so->slirp;

    if (so->so_emu == EMU_RSH && so->extra) {
        sofree(so->extra);
        so->extra = NULL;
    }
    if (so == slirp->tcp_last_so) {
        slirp->tcp_last_so = &slirp->tcb;
    } else if (so == slirp->udp_last_so) {
        slirp->udp_last_so = &slirp->udb;
    } else if (so == slirp->icmp_last_so) {
        slirp->icmp_last_so = &slirp->icmp;
    }
    m_free(so->so_m);

    if (so->so_next && so->so_prev)
        remque(so); /* crashes if so is not in a queue */

    free(so);
}

size_t sopreprbuf(struct socket *so, struct iovec *iov, int *np)
{
    int n, lss, total;
    struct sbuf *sb = &so->so_snd;
    int len = sb->sb_datalen - sb->sb_cc;
    int mss = so->so_tcpcb->t_maxseg;

    DEBUG_CALL("sopreprbuf");
    DEBUG_ARG("so = %lx", (long)so);

    if (len <= 0)
        return 0;

    iov[0].iov_base = sb->sb_wptr;
    iov[1].iov_base = NULL;
    iov[1].iov_len = 0;
    if (sb->sb_wptr < sb->sb_rptr) {
        iov[0].iov_len = sb->sb_rptr - sb->sb_wptr;
        /* Should never succeed, but... */
        if (iov[0].iov_len > len)
            iov[0].iov_len = len;
        if (iov[0].iov_len > mss)
            iov[0].iov_len -= iov[0].iov_len % mss;
        n = 1;
    } else {
        iov[0].iov_len = (sb->sb_data + sb->sb_datalen) - sb->sb_wptr;
        /* Should never succeed, but... */
        if (iov[0].iov_len > len)
            iov[0].iov_len = len;
        len -= iov[0].iov_len;
        if (len) {
            iov[1].iov_base = sb->sb_data;
            iov[1].iov_len = sb->sb_rptr - sb->sb_data;
            if (iov[1].iov_len > len)
                iov[1].iov_len = len;
            total = iov[0].iov_len + iov[1].iov_len;
            if (total > mss) {
                lss = total % mss;
                if (iov[1].iov_len > lss) {
                    iov[1].iov_len -= lss;
                    n = 2;
                } else {
                    lss -= iov[1].iov_len;
                    iov[0].iov_len -= lss;
                    n = 1;
                }
            } else
                n = 2;
        } else {
            if (iov[0].iov_len > mss)
                iov[0].iov_len -= iov[0].iov_len % mss;
            n = 1;
        }
    }
    if (np)
        *np = n;

    return iov[0].iov_len + (n - 1) * iov[1].iov_len;
}

/*
 * Read from so's socket into sb_snd, updating all relevant sbuf fields
 * NOTE: This will only be called if it is select()ed for reading, so
 * a read() of 0 (or less) means it's disconnected
 */
int soread(struct socket *so)
{
    int n, nn;
    struct sbuf *sb = &so->so_snd;
    struct iovec iov[2];

    DEBUG_CALL("soread");
    DEBUG_ARG("so = %lx", (long)so);

    /*
     * No need to check if there's enough room to read.
     * soread wouldn't have been called if there weren't
     */
    sopreprbuf(so, iov, &n);

#ifdef HAVE_READV
    nn = readv(so->s, (struct iovec *)iov, n);
    DEBUG_MISC((dfd, " ... read nn = %d bytes\n", nn));
#else
    nn = qemu_recv(so->s, iov[0].iov_base, iov[0].iov_len, 0);
#endif
    if (nn <= 0) {
        if (nn < 0 && (errno == EINTR || errno == EAGAIN))
            return 0;
        else {
            DEBUG_MISC((dfd,
                        " --- soread() disconnected, nn = %d, errno = %d-%s\n",
                        nn, errno, strerror(errno)));
            sofcantrcvmore(so);
            tcp_sockclosed(sototcpcb(so));
            return -1;
        }
    }

#ifndef HAVE_READV
    /*
     * If there was no error, try and read the second time round
     * We read again if n = 2 (ie, there's another part of the buffer)
     * and we read as much as we could in the first read
     * We don't test for <= 0 this time, because there legitimately
     * might not be any more data (since the socket is non-blocking),
     * a close will be detected on next iteration.
     * A return of -1 wont (shouldn't) happen, since it didn't happen above
     */
    if (n == 2 && nn == iov[0].iov_len) {
        int ret;
        ret = qemu_recv(so->s, iov[1].iov_base, iov[1].iov_len, 0);
        if (ret > 0)
            nn += ret;
    }

    DEBUG_MISC((dfd, " ... read nn = %d bytes\n", nn));
#endif

    /* Update fields */
    sb->sb_cc += nn;
    sb->sb_wptr += nn;
    if (sb->sb_wptr >= (sb->sb_data + sb->sb_datalen))
        sb->sb_wptr -= sb->sb_datalen;
    return nn;
}

int soreadbuf(struct socket *so, const char *buf, int size)
{
    int n, nn, copy = size;
    struct sbuf *sb = &so->so_snd;
    struct iovec iov[2];

    DEBUG_CALL("soreadbuf");
    DEBUG_ARG("so = %lx", (long)so);

    /*
     * No need to check if there's enough room to read.
     * soread wouldn't have been called if there weren't
     */
    if (sopreprbuf(so, iov, &n) < size)
        goto err;

    nn = MIN(iov[0].iov_len, copy);
    memcpy(iov[0].iov_base, buf, nn);

    copy -= nn;
    buf += nn;

    if (copy == 0)
        goto done;

    memcpy(iov[1].iov_base, buf, copy);

done:
    /* Update fields */
    sb->sb_cc += size;
    sb->sb_wptr += size;
    if (sb->sb_wptr >= (sb->sb_data + sb->sb_datalen))
        sb->sb_wptr -= sb->sb_datalen;
    return size;
err:

    sofcantrcvmore(so);
    tcp_sockclosed(sototcpcb(so));
    fprintf(stderr, "soreadbuf buffer to small");
    return -1;
}

/*
 * Get urgent data
 *
 * When the socket is created, we set it SO_OOBINLINE,
 * so when OOB data arrives, we soread() it and everything
 * in the send buffer is sent as urgent data
 */
void sorecvoob(struct socket *so)
{
    struct tcpcb *tp = sototcpcb(so);

    DEBUG_CALL("sorecvoob");
    DEBUG_ARG("so = %lx", (long)so);

    /*
     * We take a guess at how much urgent data has arrived.
     * In most situations, when urgent data arrives, the next
     * read() should get all the urgent data.  This guess will
     * be wrong however if more data arrives just after the
     * urgent data, or the read() doesn't return all the
     * urgent data.
     */
    soread(so);
    tp->snd_up = tp->snd_una + so->so_snd.sb_cc;
    tp->t_force = 1;
    tcp_output(tp);
    tp->t_force = 0;
}

/*
 * Send urgent data
 * There's a lot duplicated code here, but...
 */
int sosendoob(struct socket *so)
{
    struct sbuf *sb = &so->so_rcv;
    char buff[2048]; /* XXX Shouldn't be sending more oob data than this */

    int n, len;

    DEBUG_CALL("sosendoob");
    DEBUG_ARG("so = %lx", (long)so);
    DEBUG_ARG("sb->sb_cc = %d", sb->sb_cc);

    if (so->so_urgc > 2048)
        so->so_urgc = 2048; /* XXXX */

    if (sb->sb_rptr < sb->sb_wptr) {
        /* We can send it directly */
        n = slirp_send(so, sb->sb_rptr, so->so_urgc,
                       (MSG_OOB)); /* |MSG_DONTWAIT)); */
        so->so_urgc -= n;

        DEBUG_MISC((dfd,
                    " --- sent %d bytes urgent data, %d urgent bytes left\n", n,
                    so->so_urgc));
    } else {
        /*
         * Since there's no sendv or sendtov like writev,
         * we must copy all data to a linear buffer then
         * send it all
         */
        len = (sb->sb_data + sb->sb_datalen) - sb->sb_rptr;
        if (len > so->so_urgc)
            len = so->so_urgc;
        memcpy(buff, sb->sb_rptr, len);
        so->so_urgc -= len;
        if (so->so_urgc) {
            n = sb->sb_wptr - sb->sb_data;
            if (n > so->so_urgc)
                n = so->so_urgc;
            memcpy((buff + len), sb->sb_data, n);
            so->so_urgc -= n;
            len += n;
        }
        n = slirp_send(so, buff, len, (MSG_OOB)); /* |MSG_DONTWAIT)); */
#ifdef DEBUG
        if (n != len)
            DEBUG_ERROR((dfd, "Didn't send all data urgently XXXXX\n"));
#endif
        DEBUG_MISC((dfd,
                    " ---2 sent %d bytes urgent data, %d urgent bytes left\n",
                    n, so->so_urgc));
    }

    sb->sb_cc -= n;
    sb->sb_rptr += n;
    if (sb->sb_rptr >= (sb->sb_data + sb->sb_datalen))
        sb->sb_rptr -= sb->sb_datalen;

    return n;
}

/*
 * Write data from so_rcv to so's socket,
 * updating all sbuf field as necessary
 */
int sowrite(struct socket *so)
{
    int n, nn;
    struct sbuf *sb = &so->so_rcv;
    int len = sb->sb_cc;
    struct iovec iov[2];

    DEBUG_CALL("sowrite");
    DEBUG_ARG("so = %lx", (long)so);

    if (so->so_urgc) {
        sosendoob(so);
        if (sb->sb_cc == 0)
            return 0;
    }

    /*
     * No need to check if there's something to write,
     * sowrite wouldn't have been called otherwise
     */

    iov[0].iov_base = sb->sb_rptr;
    iov[1].iov_base = NULL;
    iov[1].iov_len = 0;
    if (sb->sb_rptr < sb->sb_wptr) {
        iov[0].iov_len = sb->sb_wptr - sb->sb_rptr;
        /* Should never succeed, but... */
        if (iov[0].iov_len > len)
            iov[0].iov_len = len;
        n = 1;
    } else {
        iov[0].iov_len = (sb->sb_data + sb->sb_datalen) - sb->sb_rptr;
        if (iov[0].iov_len > len)
            iov[0].iov_len = len;
        len -= iov[0].iov_len;
        if (len) {
            iov[1].iov_base = sb->sb_data;
            iov[1].iov_len = sb->sb_wptr - sb->sb_data;
            if (iov[1].iov_len > len)
                iov[1].iov_len = len;
            n = 2;
        } else
            n = 1;
    }
    /* Check if there's urgent data to send, and if so, send it */

#ifdef HAVE_READV
    nn = writev(so->s, (const struct iovec *)iov, n);

    DEBUG_MISC((dfd, "  ... wrote nn = %d bytes\n", nn));
#else
    nn = slirp_send(so, iov[0].iov_base, iov[0].iov_len, 0);
#endif
    /* This should never happen, but people tell me it does *shrug* */
    if (nn < 0 && (errno == EAGAIN || errno == EINTR))
        return 0;

    if (nn <= 0) {
        DEBUG_MISC(
            (dfd, " --- sowrite disconnected, so->so_state = %x, errno = %d\n",
             so->so_state, errno));
        sofcantsendmore(so);
        tcp_sockclosed(sototcpcb(so));
        return -1;
    }

#ifndef HAVE_READV
    if (n == 2 && nn == iov[0].iov_len) {
        int ret;
        ret = slirp_send(so, iov[1].iov_base, iov[1].iov_len, 0);
        if (ret > 0)
            nn += ret;
    }
    DEBUG_MISC((dfd, "  ... wrote nn = %d bytes\n", nn));
#endif

    /* Update sbuf */
    sb->sb_cc -= nn;
    sb->sb_rptr += nn;
    if (sb->sb_rptr >= (sb->sb_data + sb->sb_datalen))
        sb->sb_rptr -= sb->sb_datalen;

    /*
     * If in DRAIN mode, and there's no more data, set
     * it CANTSENDMORE
     */
    if ((so->so_state & SS_FWDRAIN) && sb->sb_cc == 0)
        sofcantsendmore(so);

    return nn;
}

/*
 * recvfrom() a UDP socket
 */
void sorecvfrom(struct socket *so)
{
    struct sockaddr_in addr;
    socklen_t addrlen = sizeof(struct sockaddr_in);

    DEBUG_CALL("sorecvfrom");
    DEBUG_ARG("so = %lx", (long)so);

    if (so->so_type == IPPROTO_ICMP) { /* This is a "ping" reply */
        char buff[256];
        int len;

        len = recvfrom(so->s, buff, 256, 0, (struct sockaddr *)&addr, &addrlen);
        /* XXX Check if reply is "correct"? */

        if (len == -1 || len == 0) {
            u_char code = ICMP_UNREACH_PORT;

            if (errno == EHOSTUNREACH)
                code = ICMP_UNREACH_HOST;
            else if (errno == ENETUNREACH)
                code = ICMP_UNREACH_NET;

            DEBUG_MISC(
                (dfd, " udp icmp rx errno = %d-%s\n", errno, strerror(errno)));
            icmp_error(so->so_m, ICMP_UNREACH, code, 0, strerror(errno));
        } else {
            icmp_reflect(so->so_m);
            so->so_m = NULL; /* Don't m_free() it again! */
        }
        /* No need for this socket anymore, udp_detach it */
        udp_detach(so);
    } else { /* A "normal" UDP packet */
        struct mbuf *m;
        int len;
#ifdef _WIN32
        unsigned long n;
#else
        int n;
#endif

        m = m_get(so->slirp);
        if (!m) {
            return;
        }
        m->m_data += IF_MAXLINKHDR;

        /*
         * XXX Shouldn't FIONREAD packets destined for port 53,
         * but I don't know the max packet size for DNS lookups
         */
        len = M_FREEROOM(m);
        /* if (so->so_fport != htons(53)) { */
        ioctlsocket(so->s, FIONREAD, &n);

        if (n > len) {
            n = (m->m_data - m->m_dat) + m->m_len + n + 1;
            m_inc(m, n);
            len = M_FREEROOM(m);
        }
        /* } */

        m->m_len = recvfrom(so->s, m->m_data, len, 0, (struct sockaddr *)&addr,
                            &addrlen);
        DEBUG_MISC((dfd, " did recvfrom %d, errno = %d-%s\n", m->m_len, errno,
                    strerror(errno)));
        if (m->m_len < 0) {
            u_char code = ICMP_UNREACH_PORT;

            if (errno == EHOSTUNREACH)
                code = ICMP_UNREACH_HOST;
            else if (errno == ENETUNREACH)
                code = ICMP_UNREACH_NET;

            DEBUG_MISC((dfd, " rx error, tx icmp ICMP_UNREACH:%i\n", code));
            icmp_error(so->so_m, ICMP_UNREACH, code, 0, strerror(errno));
            m_free(m);
        } else {
            /*
             * Hack: domain name lookup will be used the most for UDP,
             * and since they'll only be used once there's no need
             * for the 4 minute (or whatever) timeout... So we time them
             * out much quicker (10 seconds  for now...)
             */
            if (so->so_expire) {
                if (so->so_fport == htons(53))
                    so->so_expire = curtime + SO_EXPIREFAST;
                else
                    so->so_expire = curtime + SO_EXPIRE;
            }

            /*
             * If this packet was destined for CTL_ADDR,
             * make it look like that's where it came from, done by udp_output
             */
            udp_output(so, m, &addr);
        } /* rx error */
    } /* if ping packet */
}

/*
 * sendto() a socket
 */
int sosendto(struct socket *so, struct mbuf *m)
{
    Slirp *slirp = so->slirp;
    int ret;
    struct sockaddr_in addr;

    DEBUG_CALL("sosendto");
    DEBUG_ARG("so = %lx", (long)so);
    DEBUG_ARG("m = %lx", (long)m);

    addr.sin_family = AF_INET;
    if ((so->so_faddr.s_addr & slirp->vnetwork_mask.s_addr) ==
        slirp->vnetwork_addr.s_addr) {
        /* It's an alias */
        if (so->so_faddr.s_addr == slirp->vnameserver_addr.s_addr) {
            if (get_dns_addr(&addr.sin_addr) < 0)
                addr.sin_addr = loopback_addr;
        } else {
            addr.sin_addr = loopback_addr;
        }
    } else
        addr.sin_addr = so->so_faddr;
    addr.sin_port = so->so_fport;

    DEBUG_MISC((dfd,
                " sendto()ing, addr.sin_port=%d, addr.sin_addr.s_addr=%.16s\n",
                ntohs(addr.sin_port), inet_ntoa(addr.sin_addr)));

    /* Don't care what port we get */
    ret = sendto(so->s, m->m_data, m->m_len, 0, (struct sockaddr *)&addr,
                 sizeof(struct sockaddr));
    if (ret < 0)
        return -1;

    /*
     * Kill the socket if there's no reply in 4 minutes,
     * but only if it's an expirable socket
     */
    if (so->so_expire)
        so->so_expire = curtime + SO_EXPIRE;
    so->so_state &= SS_PERSISTENT_MASK;
    so->so_state |= SS_ISFCONNECTED; /* So that it gets select()ed */
    return 0;
}

/*
 * Listen for incoming TCP connections
 */
struct socket *tcp_listen(Slirp *slirp, uint32_t haddr, u_int hport,
                          uint32_t laddr, u_int lport, int flags)
{
    struct sockaddr_in addr;
    struct socket *so;
    int s, opt = 1;
    socklen_t addrlen = sizeof(addr);
    memset(&addr, 0, addrlen);

    DEBUG_CALL("tcp_listen");
    DEBUG_ARG("haddr = %x", haddr);
    DEBUG_ARG("hport = %d", hport);
    DEBUG_ARG("laddr = %x", laddr);
    DEBUG_ARG("lport = %d", lport);
    DEBUG_ARG("flags = %x", flags);

    so = socreate(slirp);
    if (!so) {
        return NULL;
    }

    /* Don't tcp_attach... we don't need so_snd nor so_rcv */
    if ((so->so_tcpcb = tcp_newtcpcb(so)) == NULL) {
        free(so);
        return NULL;
    }
    insque(so, &slirp->tcb);

    /*
     * SS_FACCEPTONCE sockets must time out.
     */
    if (flags & SS_FACCEPTONCE)
        so->so_tcpcb->t_timer[TCPT_KEEP] = TCPTV_KEEP_INIT * 2;

    so->so_state &= SS_PERSISTENT_MASK;
    so->so_state |= (SS_FACCEPTCONN | flags);
    so->so_lport = lport; /* Kept in network format */
    so->so_laddr.s_addr = laddr; /* Ditto */

    addr.sin_family = AF_INET;
    addr.sin_addr.s_addr = haddr;
    addr.sin_port = hport;

    if (((s = qemu_socket(AF_INET, SOCK_STREAM, 0)) < 0) ||
        (qemu_setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(int)) < 0) ||
        (bind(s, (struct sockaddr *)&addr, sizeof(addr)) < 0) ||
        (listen(s, 1) < 0)) {
        int tmperrno = errno; /* Don't clobber the real reason we failed */

        close(s);
        sofree(so);
        /* Restore the real errno */
#ifdef _WIN32
        WSASetLastError(tmperrno);
#else
        errno = tmperrno;
#endif
        return NULL;
    }
    qemu_setsockopt(s, SOL_SOCKET, SO_OOBINLINE, &opt, sizeof(int));

    getsockname(s, (struct sockaddr *)&addr, &addrlen);
    so->so_fport = addr.sin_port;
    if (addr.sin_addr.s_addr == 0 ||
        addr.sin_addr.s_addr == loopback_addr.s_addr)
        so->so_faddr = slirp->vhost_addr;
    else
        so->so_faddr = addr.sin_addr;

    so->s = s;
    return so;
}

/*
 * Various session state calls
 * XXX Should be #define's
 * The socket state stuff needs work, these often get call 2 or 3
 * times each when only 1 was needed
 */
void soisfconnecting(struct socket *so)
{
    so->so_state &= ~(SS_NOFDREF | SS_ISFCONNECTED | SS_FCANTRCVMORE |
                      SS_FCANTSENDMORE | SS_FWDRAIN);
    so->so_state |= SS_ISFCONNECTING; /* Clobber other states */
}

void soisfconnected(struct socket *so)
{
    so->so_state &= ~(SS_ISFCONNECTING | SS_FWDRAIN | SS_NOFDREF);
    so->so_state |= SS_ISFCONNECTED; /* Clobber other states */
}

static void sofcantrcvmore(struct socket *so)
{
    if ((so->so_state & SS_NOFDREF) == 0) {
        shutdown(so->s, 0);
    }
    so->so_state &= ~(SS_ISFCONNECTING);
    if (so->so_state & SS_FCANTSENDMORE) {
        so->so_state &= SS_PERSISTENT_MASK;
        so->so_state |= SS_NOFDREF; /* Don't select it */
    } else {
        so->so_state |= SS_FCANTRCVMORE;
    }
}

static void sofcantsendmore(struct socket *so)
{
    if ((so->so_state & SS_NOFDREF) == 0) {
        shutdown(so->s, 1); /* send FIN to fhost */
    }
    so->so_state &= ~(SS_ISFCONNECTING);
    if (so->so_state & SS_FCANTRCVMORE) {
        so->so_state &= SS_PERSISTENT_MASK;
        so->so_state |= SS_NOFDREF; /* as above */
    } else {
        so->so_state |= SS_FCANTSENDMORE;
    }
}

/*
 * Set write drain mode
 * Set CANTSENDMORE once all data has been write()n
 */
void sofwdrain(struct socket *so)
{
    if (so->so_rcv.sb_cc)
        so->so_state |= SS_FWDRAIN;
    else
        sofcantsendmore(so);
}