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tcpsvd: don't keep shared fd open if fd limit is reached. closes 9331

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Also, much improved help text.

function                                             old     new   delta
packed_usage                                       30652   30851    +199
tcpudpsvd_main                                      1782    1784      +2

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2016-10-07 15:56:47 +02:00
parent 561639a68c
commit ec1ea16337
1 changed files with 46 additions and 23 deletions
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69
networking/tcpudp.c
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@ -34,37 +34,56 @@
/* with not-implemented options: */
/* //usage: "[-hpEvv] [-c N] [-C N[:MSG]] [-b N] [-u USER] [-l NAME] [-i DIR|-x CDB] [-t SEC] IP PORT PROG" */
//usage:#define tcpsvd_full_usage "\n\n"
//usage: "Create TCP socket, bind to IP:PORT and listen\n"
//usage: "for incoming connection. Run PROG for each connection.\n"
//usage: "\n IP IP to listen on, 0 = all"
//usage: "\n PORT Port to listen on"
//usage: "Create TCP socket, bind to IP:PORT and listen for incoming connections.\n"
//usage: "Run PROG for each connection.\n"
//usage: "\n IP PORT IP:PORT to listen on"
//usage: "\n PROG ARGS Program to run"
//usage: "\n -l NAME Local hostname (else looks up local hostname in DNS)"
//usage: "\n -u USER[:GRP] Change to user/group after bind"
//usage: "\n -c N Handle up to N connections simultaneously"
//usage: "\n -b N Allow a backlog of approximately N TCP SYNs"
//usage: "\n -C N[:MSG] Allow only up to N connections from the same IP"
//usage: "\n New connections from this IP address are closed"
//usage: "\n immediately. MSG is written to the peer before close"
//usage: "\n -c N Up to N connections simultaneously (default 30)"
//usage: "\n -b N Allow backlog of approximately N TCP SYNs (default 20)"
//usage: "\n -C N[:MSG] Allow only up to N connections from the same IP:"
//usage: "\n new connections from this IP address are closed"
//usage: "\n immediately, MSG is written to the peer before close"
//usage: "\n -E Don't set up environment"
//usage: "\n -h Look up peer's hostname"
//usage: "\n -E Don't set up environment variables"
//usage: "\n -l NAME Local hostname (else look up local hostname in DNS)"
//usage: "\n -v Verbose"
//usage: "\n"
//usage: "\nEnvironment if no -E:"
//usage: "\nPROTO='TCP'"
//usage: "\nTCPREMOTEADDR='ip:port'" IF_FEATURE_IPV6(" ('[ip]:port' for IPv6)")
//usage: "\nTCPLOCALADDR='ip:port'"
//usage: "\nTCPORIGDSTADDR='ip:port' of destination before firewall"
//usage: "\n Useful for REDIRECTed-to-local connections:"
//usage: "\n iptables -t nat -A PREROUTING -p tcp --dport 80 -j REDIRECT --to 8080"
//usage: "\nTCPCONCURRENCY=num_of_connects_from_this_ip"
//usage: "\nIf -h:"
//usage: "\nTCPLOCALHOST='hostname' (-l NAME is used if specified)"
//usage: "\nTCPREMOTEHOST='hostname'"
//usage:
//usage:#define udpsvd_trivial_usage
//usage: "[-hEv] [-c N] [-u USER] [-l NAME] IP PORT PROG"
//usage:#define udpsvd_full_usage "\n\n"
//usage: "Create UDP socket, bind to IP:PORT and wait\n"
//usage: "for incoming packets. Run PROG for each packet,\n"
//usage: "redirecting all further packets with same peer ip:port to it.\n"
//usage: "\n IP IP to listen on, 0 = all"
//usage: "\n PORT Port to listen on"
//usage: "Create UDP socket, bind to IP:PORT and wait for incoming packets.\n"
//usage: "Run PROG for each packet, redirecting all further packets with same\n"
//usage: "peer ip:port to it.\n"
//usage: "\n IP PORT IP:PORT to listen on"
//usage: "\n PROG ARGS Program to run"
//usage: "\n -l NAME Local hostname (else looks up local hostname in DNS)"
//usage: "\n -u USER[:GRP] Change to user/group after bind"
//usage: "\n -c N Handle up to N connections simultaneously"
//usage: "\n -c N Up to N connections simultaneously (default 30)"
//usage: "\n -E Don't set up environment"
//usage: "\n -h Look up peer's hostname"
//usage: "\n -E Don't set up environment variables"
//usage: "\n -l NAME Local hostname (else look up local hostname in DNS)"
//usage: "\n -v Verbose"
//usage: "\n"
//usage: "\nEnvironment if no -E:"
//usage: "\nPROTO='UDP'"
//usage: "\nUDPREMOTEADDR='ip:port'" IF_FEATURE_IPV6(" ('[ip]:port' for IPv6)")
//usage: "\nUDPLOCALADDR='ip:port'"
//usage: "\nIf -h:"
//usage: "\nUDPLOCALHOST='hostname' (-l NAME is used if specified)"
//usage: "\nUDPREMOTEHOST='hostname'"
#include "libbb.h"
#include "common_bufsiz.h"
@ -240,7 +259,7 @@ int tcpudpsvd_main(int argc UNUSED_PARAM, char **argv)
);
#else
/* "+": stop on first non-option */
opts = getopt32(argv, "+c:C:i:x:u:l:Eb:hpt:v",
opts = getopt32(argv, "+c:+C:i:x:u:l:Eb:hpt:v",
&cmax, &str_C, &instructs, &instructs, &user, &preset_local_hostname,
&backlog, &str_t, &verbose
);
@ -349,16 +368,20 @@ int tcpudpsvd_main(int argc UNUSED_PARAM, char **argv)
again:
hccp = NULL;
again1:
close(0);
/* It's important to close(0) _before_ wait loop:
* fd#0 can be a shared connection fd.
* If kept open by us, peer can't detect PROG closing it.
*/
while (cnum >= cmax)
wait_for_any_sig(); /* expecting SIGCHLD */
/* Accept a connection to fd #0 */
again1:
close(0);
again2:
sig_unblock(SIGCHLD);
local.len = remote.len = sa_len;
if (tcp) {
/* Accept a connection to fd #0 */
conn = accept(sock, &remote.u.sa, &remote.len);
} else {
/* In case recv_from_to won't be able to recover local addr.