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linux,udp: enable full ICMP error reporting

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The Linux kernel suppresses some ICMP error messages by default for UDP
sockets. This commit sets IP_RECVERR/IPV6_RECVERR on the socket to
enable full ICMP error reporting, hopefully resulting in faster failover
to working name servers.

PR-URL: https://github.com/libuv/libuv/pull/2872
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com>
This commit is contained in:
Ondřej Surý 2020-05-29 10:17:32 +02:00 committed by Santiago Gimeno
parent c464d21323
commit c382d39a85
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GPG Key ID: F28C3C8DA33C03BE
3 changed files with 47 additions and 3 deletions
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11
docs/src/udp.rst
View File

@ -53,6 +53,14 @@ Data types
* in uv_udp_recv_cb, nread will always be 0 and addr will always be NULL.
*/
UV_UDP_MMSG_FREE = 16,
/*
* Indicates if IP_RECVERR/IPV6_RECVERR will be set when binding the handle.
* This sets IP_RECVERR for IPv4 and IPV6_RECVERR for IPv6 UDP sockets on
* Linux. This stops the Linux kernel from supressing some ICMP error messages
* and enables full ICMP error reporting for faster failover.
* This flag is no-op on platforms other than Linux.
*/
UV_UDP_LINUX_RECVERR = 32,
/*
* Indicates that recvmmsg should be used, if available.
*/
@ -178,7 +186,8 @@ API
with the address and port to bind to.
:param flags: Indicate how the socket will be bound,
``UV_UDP_IPV6ONLY`` and ``UV_UDP_REUSEADDR`` are supported.
``UV_UDP_IPV6ONLY``, ``UV_UDP_REUSEADDR``, and ``UV_UDP_RECVERR``
are supported.
:returns: 0 on success, or an error code < 0 on failure.

9
include/uv.h
View File

@ -626,7 +626,14 @@ enum uv_udp_flags {
* in uv_udp_recv_cb, nread will always be 0 and addr will always be NULL.
*/
UV_UDP_MMSG_FREE = 16,
/*
* Indicates if IP_RECVERR/IPV6_RECVERR will be set when binding the handle.
* This sets IP_RECVERR for IPv4 and IPV6_RECVERR for IPv6 UDP sockets on
* Linux. This stops the Linux kernel from supressing some ICMP error messages
* and enables full ICMP error reporting for faster failover.
* This flag is no-op on platforms other than Linux.
*/
UV_UDP_LINUX_RECVERR = 32,
/*
* Indicates that recvmmsg should be used, if available.
*/

30
src/unix/udp.c
View File

@ -504,6 +504,28 @@ static int uv__set_reuse(int fd) {
return 0;
}
/*
* The Linux kernel suppresses some ICMP error messages by default for UDP
* sockets. Setting IP_RECVERR/IPV6_RECVERR on the socket enables full ICMP
* error reporting, hopefully resulting in faster failover to working name
* servers.
*/
static int uv__set_recverr(int fd, sa_family_t ss_family) {
#if defined(__linux__)
int yes;
yes = 1;
if (ss_family == AF_INET) {
if (setsockopt(fd, IPPROTO_IP, IP_RECVERR, &yes, sizeof(yes)))
return UV__ERR(errno);
} else if (ss_family == AF_INET6) {
if (setsockopt(fd, IPPROTO_IPV6, IPV6_RECVERR, &yes, sizeof(yes)))
return UV__ERR(errno);
}
#endif
return 0;
}
int uv__udp_bind(uv_udp_t* handle,
const struct sockaddr* addr,
@ -514,7 +536,7 @@ int uv__udp_bind(uv_udp_t* handle,
int fd;
/* Check for bad flags. */
if (flags & ~(UV_UDP_IPV6ONLY | UV_UDP_REUSEADDR))
if (flags & ~(UV_UDP_IPV6ONLY | UV_UDP_REUSEADDR | UV_UDP_LINUX_RECVERR))
return UV_EINVAL;
/* Cannot set IPv6-only mode on non-IPv6 socket. */
@ -530,6 +552,12 @@ int uv__udp_bind(uv_udp_t* handle,
handle->io_watcher.fd = fd;
}
if (flags & UV_UDP_LINUX_RECVERR) {
err = uv__set_recverr(fd, addr->sa_family);
if (err)
return err;
}
if (flags & UV_UDP_REUSEADDR) {
err = uv__set_reuse(fd);
if (err)