ec1ea1633
Denys Vlasenko
2016-10-07
Subject
tcpsvd: don't keep shared fd open if fd limit is reached. closes 9331
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networking/tcpudp.c+46 -23
| @@ -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. | |