src/os/unix/ngx_channel.c

/*
 * Copyright (C) Igor Sysoev
 */


#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_channel.h>


ngx_int_t ngx_write_channel(ngx_socket_t s, ngx_channel_t *ch, size_t size,
                            ngx_log_t *log) 
{
    ssize_t             n;
    ngx_err_t           err;
    struct iovec        iov[1];
    struct msghdr       msg;

#if (NGX_HAVE_MSGHDR_MSG_CONTROL)

    union {
        struct cmsghdr  cm;
        char            space[CMSG_SPACE(sizeof(int))];
    } cmsg;

    if (ch->fd == -1) {
        msg.msg_control = NULL;
        msg.msg_controllen = 0;

    } else {
        msg.msg_control = (caddr_t) &cmsg;
        msg.msg_controllen = sizeof(cmsg);

        cmsg.cm.cmsg_len = sizeof(cmsg);
        cmsg.cm.cmsg_level = SOL_SOCKET; 
        cmsg.cm.cmsg_type = SCM_RIGHTS;
        *(int *) CMSG_DATA(&cmsg.cm) = ch->fd;
    }

    msg.msg_flags = 0;

#else

    if (ch->fd == -1) {
        msg.msg_accrights = NULL;
        msg.msg_accrightslen = 0;

    } else {
        msg.msg_accrights = (caddr_t) &ch->fd;
        msg.msg_accrightslen = sizeof(int);
    }

#endif

    iov[0].iov_base = (char *) ch;
    iov[0].iov_len = size;

    msg.msg_name = NULL;
    msg.msg_namelen = 0;
    msg.msg_iov = iov;
    msg.msg_iovlen = 1;

    n = sendmsg(s, &msg, 0);

    if (n == -1) {
        err = ngx_errno;
        if (err == NGX_EAGAIN) {
            return NGX_AGAIN;
        }

        ngx_log_error(NGX_LOG_ALERT, log, err, "sendmsg() failed");
        return NGX_ERROR;
    }

    return NGX_OK;
}


ngx_int_t ngx_read_channel(ngx_socket_t s, ngx_channel_t *ch, size_t size,
                           ngx_log_t *log)
{   
    ssize_t             n;
    ngx_err_t           err;
    struct iovec        iov[1];
    struct msghdr       msg;

#if (NGX_HAVE_MSGHDR_MSG_CONTROL)
    union {
        struct cmsghdr  cm;
        char            space[CMSG_SPACE(sizeof(int))];
    } cmsg;
#else
    int                 fd;
#endif

    iov[0].iov_base = (char *) ch;
    iov[0].iov_len = size;

    msg.msg_name = NULL;
    msg.msg_namelen = 0;
    msg.msg_iov = iov;
    msg.msg_iovlen = 1;

#if (NGX_HAVE_MSGHDR_MSG_CONTROL)
    msg.msg_control = (caddr_t) &cmsg;
    msg.msg_controllen = sizeof(cmsg);
#else
    msg.msg_accrights = (caddr_t) &fd;
    msg.msg_accrightslen = sizeof(int);
#endif

    n = recvmsg(s, &msg, 0);

    if (n == -1) {
        err = ngx_errno;
        if (err == NGX_EAGAIN) {
            return NGX_AGAIN;
        }

        ngx_log_error(NGX_LOG_ALERT, log, err, "recvmsg() failed");
        return NGX_ERROR;
    }

    if (n == 0) {
        ngx_log_debug0(NGX_LOG_DEBUG_CORE, log, 0, "recvmsg() returned zero");
        return NGX_ERROR;
    }

    if ((size_t) n < sizeof(ngx_channel_t)) {
        ngx_log_error(NGX_LOG_ALERT, log, 0,
                      "recvmsg() returned not enough data: %uz", n);
        return NGX_ERROR;
    }

#if (NGX_HAVE_MSGHDR_MSG_CONTROL)

    if (ch->command == NGX_CMD_OPEN_CHANNEL) {

        if (cmsg.cm.cmsg_len < (socklen_t) sizeof(cmsg)) {
            ngx_log_error(NGX_LOG_ALERT, log, 0,
                          "recvmsg() returned too small ancillary data");
            return NGX_ERROR;
        }

        if (cmsg.cm.cmsg_level != SOL_SOCKET || cmsg.cm.cmsg_type != SCM_RIGHTS)
        {
            ngx_log_error(NGX_LOG_ALERT, log, 0,
                          "recvmsg() returned invalid ancillary data "
                          "level %d or type %d",
                          cmsg.cm.cmsg_level, cmsg.cm.cmsg_type);
            return NGX_ERROR;
        }

        ch->fd = *(int *) CMSG_DATA(&cmsg.cm);
    }

    if (msg.msg_flags & (MSG_TRUNC|MSG_CTRUNC)) {
        ngx_log_error(NGX_LOG_ALERT, log, 0,
                      "recvmsg() truncated data");
    }

#else

    if (ch->command == NGX_CMD_OPEN_CHANNEL) {
        if (msg.msg_accrightslen != sizeof(int)) {
            ngx_log_error(NGX_LOG_ALERT, log, 0, 
                          "recvmsg() returned no ancillary data");
            return NGX_ERROR;
        }

        ch->fd = fd;
    }

#endif

    return n;
}


ngx_int_t ngx_add_channel_event(ngx_cycle_t *cycle, ngx_fd_t fd,
                                ngx_int_t event, ngx_event_handler_pt handler)
{
    ngx_event_t       *ev, *rev, *wev;
    ngx_connection_t  *c;

    c = &cycle->connections[fd];
    rev = &cycle->read_events[fd];
    wev = &cycle->write_events[fd];

    ngx_memzero(c, sizeof(ngx_connection_t));
    ngx_memzero(rev, sizeof(ngx_event_t));
    ngx_memzero(wev, sizeof(ngx_event_t));

    c->fd = fd;
    c->pool = cycle->pool;

    c->read = rev;
    c->write = wev;

    c->log = cycle->log;
    rev->log = cycle->log;
    wev->log = cycle->log;
    rev->index = NGX_INVALID_INDEX;
    wev->index = NGX_INVALID_INDEX;
    rev->data = c;
    wev->data = c;

#if (NGX_THREADS)
    rev->lock = &c->lock;
    wev->lock = &c->lock;
    rev->own_lock = &c->lock;
    wev->own_lock = &c->lock;
#endif

    ev = (event == NGX_READ_EVENT) ? rev : wev;

    ev->handler = handler;

    if (ngx_add_conn && (ngx_event_flags & NGX_USE_EPOLL_EVENT) == 0) {
        if (ngx_add_conn(c) == NGX_ERROR) {
            return NGX_ERROR;
        }
    
    } else { 
        if (ngx_add_event(ev, event, 0) == NGX_ERROR) {
            return NGX_ERROR;
        }
    }

    return NGX_OK;
}


void ngx_close_channel(ngx_fd_t *fd, ngx_log_t *log)
{
    if (close(fd[0]) == -1) {
        ngx_log_error(NGX_LOG_ALERT, log, ngx_errno, "close() channel failed");
    }

    if (close(fd[1]) == -1) {
        ngx_log_error(NGX_LOG_ALERT, log, ngx_errno, "close() channel failed");
    }
}