Mercurial > hg > nginx-quic
view src/os/unix/ngx_channel.c @ 8867:5119c8150478
Fixed runtime handling of systems without EPOLLRDHUP support.
In 7583:efd71d49bde0 (nginx 1.17.5) along with introduction of the
ioctl(FIONREAD) support proper handling of systems without EPOLLRDHUP
support in the kernel (but with EPOLLRDHUP in headers) was broken.
Before the change, rev->available was never set to 0 unless
ngx_use_epoll_rdhup was also set (that is, runtime test for EPOLLRDHUP
introduced in 6536:f7849bfb6d21 succeeded). After the change,
rev->available might reach 0 on systems without runtime EPOLLRDHUP
support, stopping further reading in ngx_readv_chain() and ngx_unix_recv().
And, if EOF happened to be already reported along with the last event,
it is not reported again by epoll_wait(), leading to connection hangs
and timeouts on such systems.
This affects Linux kernels before 2.6.17 if nginx was compiled
with newer headers, and, more importantly, emulation layers, such as
DigitalOcean's App Platform's / gVisor's epoll emulation layer.
Fix is to explicitly check ngx_use_epoll_rdhup before the corresponding
rev->pending_eof tests in ngx_readv_chain() and ngx_unix_recv().
author | Marcus Ball <marcus.ball@live.com> |
---|---|
date | Mon, 30 May 2022 02:38:07 +0300 |
parents | 3377f9459e99 |
children |
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/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #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); ngx_memzero(&cmsg, sizeof(cmsg)); cmsg.cm.cmsg_len = CMSG_LEN(sizeof(int)); cmsg.cm.cmsg_level = SOL_SOCKET; cmsg.cm.cmsg_type = SCM_RIGHTS; /* * We have to use ngx_memcpy() instead of simple * *(int *) CMSG_DATA(&cmsg.cm) = ch->fd; * because some gcc 4.4 with -O2/3/s optimization issues the warning: * dereferencing type-punned pointer will break strict-aliasing rules * * Fortunately, gcc with -O1 compiles this ngx_memcpy() * in the same simple assignment as in the code above */ ngx_memcpy(CMSG_DATA(&cmsg.cm), &ch->fd, sizeof(int)); } 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: %z", n); return NGX_ERROR; } #if (NGX_HAVE_MSGHDR_MSG_CONTROL) if (ch->command == NGX_CMD_OPEN_CHANNEL) { if (cmsg.cm.cmsg_len < (socklen_t) CMSG_LEN(sizeof(int))) { 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); */ ngx_memcpy(&ch->fd, CMSG_DATA(&cmsg.cm), sizeof(int)); } 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 = ngx_get_connection(fd, cycle->log); if (c == NULL) { return NGX_ERROR; } c->pool = cycle->pool; rev = c->read; wev = c->write; rev->log = cycle->log; wev->log = cycle->log; rev->channel = 1; wev->channel = 1; 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) { ngx_free_connection(c); return NGX_ERROR; } } else { if (ngx_add_event(ev, event, 0) == NGX_ERROR) { ngx_free_connection(c); 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"); } }