bcollet/socat
1
0
Fork 0
mirror of https://repo.or.cz/socat.git synced 2024-12-22 15:32:35 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions

Prevent error loop on RECVFROM addresses with fork

Browse source
This commit is contained in:
Gerhard Rieger 2020-12-26 19:03:32 +01:00
parent 10680c8aad
commit ff8de6c5cd
3 changed files with 27 additions and 3 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

7
CHANGES
View file

@ -43,6 +43,13 @@ Corrections:
is now increased to 2047 bytes.
Change suggested by Mario Camou.
Addresses of type RECVFROM with option fork looped with an error
message in case that the second address failed before consuming the
packet. The fix makes RECVFROM drop the packet when the second address
failed before reading it. Use retry or forever option with the second
address if you want to avoid data loss.
Thanks to Chunmei Xu for reporting this issue and proving the patch.
Porting:
In gcc version 10 the default changed from -fcommon to -fno-common.
Consequently, linking filan and procan failed with error

14
doc/socat.yo
View file

@ -419,6 +419,7 @@ label(ADDRESS_IP_RECVFROM)dit(bf(tt(IP-RECVFROM:<protocol>)))
This address works well with IP-SENDTO address peers (see above).
Protocol 255 uses the raw socket with the IP header being part of the
data.nl()
See the link(note about RECVFROM addresses)(NOTE_RECVFROM).nl()
Option groups: link(FD)(GROUP_FD),link(SOCKET)(GROUP_SOCKET),link(IP4)(GROUP_IP4),link(IP6)(GROUP_IP6),link(CHILD)(GROUP_CHILD),link(RANGE)(GROUP_RANGE) nl()
Useful options:
link(pf)(OPTION_PROTOCOL_FAMILY),
@ -790,6 +791,7 @@ label(ADDRESS_SOCKET_RECVFROM)dit(bf(tt(SOCKET-RECVFROM:<domain>:<type>:<protoco
to find the appropriate values. The local-address must be the
link(data)(TYPE_DATA) representation of a sockaddr structure without
sa_family and (BSD) sa_len components.nl()
See the link(note about RECVFROM addresses)(NOTE_RECVFROM).nl()
Option groups: link(FD)(GROUP_FD),link(SOCKET)(GROUP_SOCKET),link(CHILD)(GROUP_CHILD),link(RANGE)(GROUP_RANGE)nl()
Useful options:
link(fork)(OPTION_FORK),
@ -1113,11 +1115,15 @@ label(ADDRESS_UDP_RECVFROM)dit(bf(tt(UDP-RECVFROM:<port>)))
UDP/IP version 4 or 6
depending on option link(pf)(OPTION_PROTOCOL_FAMILY).
It receives one packet from an unspecified peer and may send one or more
answer packets to that peer. This mode is particularly useful with fork
option
answer packets to that peer. This mode is particularly useful with
link(fork)(OPTION_FORK) option
where each arriving packet - from arbitrary peers - is handled by its own sub
process. This allows a behaviour similar to typical UDP based servers like ntpd
or named. This address works well with socat UDP-SENDTO address peers.nl()
label(NOTE_RECVFROM)Note: When the second address fails before entering the transfer loop the
packet is dropped. Use option link(retry)(OPTION_RETRY) or
link(forever)(OPTION_FOREVER) on the second address to avoid data loss.
nl()
Option groups: link(FD)(GROUP_FD),link(SOCKET)(GROUP_SOCKET),link(IP4)(GROUP_IP4),link(IP6)(GROUP_IP6),link(CHILD)(GROUP_CHILD),link(RANGE)(GROUP_RANGE) nl()
Useful options:
link(fork)(OPTION_FORK),
@ -1233,6 +1239,7 @@ label(ADDRESS_UNIX_RECVFROM)dit(bf(tt(UNIX-RECVFROM:<filename>)))
This mode is particularly useful with fork option where each arriving packet - from arbitrary peers - is handled by its own sub process.
This address works well with socat UNIX-SENDTO address peers.nl()
Option groups: link(FD)(GROUP_FD),link(SOCKET)(GROUP_SOCKET),link(NAMED)(GROUP_NAMED),link(CHILD)(GROUP_CHILD),link(UNIX)(GROUP_SOCK_UNIX) nl()
See the link(note about RECVFROM addresses)(NOTE_RECVFROM).nl()
Useful options:
link(fork)(OPTION_FORK)nl()
See also:
@ -2310,7 +2317,8 @@ label(OPTION_FORK)dit(bf(tt(fork)))
child:
OPENSSL-LISTEN forks em(before) the SSL handshake, while OPENSSL-CONNECT
forks em(afterwards).
RETRY and FOREVER options are not inherited by the child process.nl()
link(retry)(OPTION_RETRY) and link(forever)(OPTION_FOREVER) options are not
inherited by the child process.nl()
On some operating systems (e.g. FreeBSD) this option does not work for
UDP-LISTEN addresses.nl()
enddit()

9
xio-socket.c
View file

@ -1128,6 +1128,8 @@ static pid_t xio_waitingfor; /* info from recv loop to signal handler:
that should send us the USR1 signal */
static bool xio_hashappened; /* info from signal handler to loop: child
process has read ("consumed") the packet */
static int xio_childstatus;
/* this is the signal handler for USR1 and CHLD */
void xiosigaction_hasread(int signum
#if HAVE_STRUCT_SIGACTION_SA_SIGACTION && defined(SA_SIGINFO)
@ -1179,6 +1181,7 @@ void xiosigaction_hasread(int signum
}
if (pid == xio_waitingfor) {
xio_hashappened = true;
xio_childstatus = WEXITSTATUS(status);
Debug("xiosigaction_hasread() ->");
diag_in_handler = 0;
errno = _errno;
@ -1480,6 +1483,12 @@ int _xioopen_dgram_recvfrom(struct single *xfd, int xioflags,
xio_waitingfor = 0; /* so this child will not set hashappened again */
xio_hashappened = false;
if (xio_childstatus != 0) {
char buff[512];
Recv(xfd->fd, buff, sizeof(buff), 0);
xio_childstatus = 0;
Info("drop data because of child exit failed");
}
Info("continue listening");
} else {
break;