From 994526dbc4a6b836e5cdc517f524c10cef56e1b4 Mon Sep 17 00:00:00 2001 From: Vladimir Dubrovin <3proxy@3proxy.ru> Date: Tue, 20 Oct 2026 19:02:37 +0300 Subject: [PATCH] resolver: sysresolve, names resolved by the system routines The command keeps the C library's resolution which a configuration without nserver had before the system's name servers became the default: no hosts file imported. nserver lines, if any, are still there for dnspr to forward to. Of sysresolve and fakeresolve the last given applies. Tests: sysdns, with sysresolve dnspr has no hosts file names and a name is resolved through the system routines. Co-Authored-By: Claude Opus 5.5 --- doc/html/man5/3proxy.cfg.5.html | 12 +++++++++++- man/3proxy.cfg.5 | 11 ++++++++++- src/conf.c | 14 ++++++++++++-- src/proxy.h | 2 +- src/resolve.c | 11 +++++++++-- tests/cases/sysdns.py | 25 ++++++++++++++++++++++++- 6 files changed, 67 insertions(+), 8 deletions(-) diff --git a/doc/html/man5/3proxy.cfg.5.html b/doc/html/man5/3proxy.cfg.5.html index d424c64..85873f8 100644 --- a/doc/html/man5/3proxy.cfg.5.html +++ b/doc/html/man5/3proxy.cfg.5.html @@ -498,6 +498,15 @@ user), Reply-Message. Use authcache to speedup authentication. RADIUS feature is currently experimental.

+

sysresolve +
+Names are resolved by the system routines for name +resolution (the C library), as without nserver before +the system's name servers became the default; the hosts file +is not imported. nserver lines, if any, are still used +by dnspr to forward queries. Of sysresolve and +fakeresolve the last one given applies.

+

nserver <ipaddr>[:port][/tcp]
Nameserver to use for name resolutions; up to 3, asked in @@ -507,7 +516,8 @@ has to be enclosed in square brackets:
nserver 1.1.1.1
nserver [2001:4860:4860::8844]
nserver [2001:4860:4860::8844]:5353/tcp
-If none is specified (and there is no fakeresolve), +If none is specified (and there is no fakeresolve or +sysresolve), the system's name servers are used: up to 3 from /etc/resolv.conf, on Windows from the registry (those set for the system, those set for an interface, then those diff --git a/man/3proxy.cfg.5 b/man/3proxy.cfg.5 index b03c629..7c7bd94 100644 --- a/man/3proxy.cfg.5 +++ b/man/3proxy.cfg.5 @@ -555,7 +555,7 @@ An IPv6 address has to be enclosed in square brackets: .br \fBnserver [2001:4860:4860::8844]:5353/tcp\fR .br - If none is specified (and there is no \fBfakeresolve\fR), the system's name + If none is specified (and there is no \fBfakeresolve\fR or \fBsysresolve\fR), the system's name servers are used: up to 3 from \fI/etc/resolv.conf\fR, on Windows from the registry (those set for the system, those set for an interface, then those DHCP gave). Names in the hosts file (\fI/etc/hosts\fR, on Windows @@ -600,6 +600,15 @@ are never consulted. A static record takes precedence over the hosts file. If 0. is used as a hostaddr host will never resolve, it can be used to blacklist something. +.br +.B sysresolve +.br + Names are resolved by the system routines for name resolution (the C +library), as without \fBnserver\fR before the system's name servers became +the default; the hosts file is not imported. \fBnserver\fR lines, if any, are +still used by \fBdnspr\fR to forward queries. Of \fBsysresolve\fR and +\fBfakeresolve\fR the last one given applies. + .br .B fakeresolve .br diff --git a/src/conf.c b/src/conf.c index 7e08461..a235fdd 100644 --- a/src/conf.c +++ b/src/conf.c @@ -741,6 +741,8 @@ static int h_flushusers(int argc, unsigned char **argv){ force (the process has one list) once it is committed */ static struct nserver cfgns[MAXNSERVERS]; static int cfgnsn = 0; +/* sysresolve: names resolved by the system routines */ +static int cfgsysresolve = 0; static int h_nserver(int argc, unsigned char **argv){ char *str; @@ -764,13 +766,13 @@ static int h_nserver(int argc, unsigned char **argv){ /* The configuration's name servers, or the system's in their place */ void confdnscommit(struct extparam *c){ - sysdnsapply(c, cfgns, cfgnsn); + sysdnsapply(c, cfgns, cfgnsn, cfgsysresolve); } /* Whether names would be resolved slowly: by the C library, or by name servers, the system's taken by default, without a cache */ static int noresolver(void){ - if(!conf->resolvfunc && !sysdnscount()) return 1; + if(cfgsysresolve || (!conf->resolvfunc && !sysdnscount())) return 1; return (!conf->resolvfunc || conf->resolvfunc == myresolver) && !dns_table.poolsize; } @@ -790,6 +792,12 @@ static int h_authnserver(int argc, unsigned char **argv){ static int h_fakeresolve(int argc, unsigned char **argv){ conf->resolvfunc = fakeresolver; + cfgsysresolve = 0; + return 0; +} + +static int h_sysresolve(int argc, unsigned char **argv){ + cfgsysresolve = 1; return 0; } @@ -2146,6 +2154,7 @@ struct commands commandhandlers[]={ {NULL, "flush", h_flush, 1, 1}, {NULL, "nserver", h_nserver, 2, 2}, {NULL, "fakeresolve", h_fakeresolve, 1, 1}, + {NULL, "sysresolve", h_sysresolve, 1, 1}, {NULL, "nscache", h_nscache, 2, 2}, {NULL, "nscache6", h_nscache6, 2, 2}, {NULL, "nsrecord", h_nsrecord, 3, 3}, @@ -2534,6 +2543,7 @@ void confbegin(void){ char * args[] = {"auth", "iponly", NULL}; cfgnsn = 0; + cfgsysresolve = 0; h_auth(2, (unsigned char **)args); } diff --git a/src/proxy.h b/src/proxy.h index 972ce1f..cf90e37 100644 --- a/src/proxy.h +++ b/src/proxy.h @@ -435,7 +435,7 @@ int nscacheresolv(int af, unsigned char *name, unsigned char *value, uint32_t *t void setnservers(const struct nserver *ns, int n); void sysdnsinit(void); int sysdnscount(void); -void sysdnsapply(struct extparam *c, const struct nserver *ns, int n); +void sysdnsapply(struct extparam *c, const struct nserver *ns, int n, int sysresolve); void sysdnscheck(void); void confdnscommit(struct extparam *c); uint32_t udpresolve(int af, unsigned char * name, unsigned char * value, uint32_t *retttl, struct clientparam* param, int makeauth); diff --git a/src/resolve.c b/src/resolve.c index 0be7c1d..7989ca3 100644 --- a/src/resolve.c +++ b/src/resolve.c @@ -585,9 +585,16 @@ int sysdnscount(void){ /* A configuration committed: the name servers of its nserver lines, else, with nothing else to resolve names, the system's and its hosts file, read - again. Until then those in force stay. */ -void sysdnsapply(struct extparam *c, const struct nserver *ns, int n){ + again. Until then those in force stay. With sysresolve the system + routines resolve names, nserver lines left to dnspr. */ +void sysdnsapply(struct extparam *c, const struct nserver *ns, int n, int sysresolve){ sysdns.active = 0; + if(sysresolve){ + c->resolvfunc = NULL; + setnservers(ns, n); + hostsremove(); + return; + } if(n){ setnservers(ns, n); hostsremove(); diff --git a/tests/cases/sysdns.py b/tests/cases/sysdns.py index e4b949b..38e156f 100644 --- a/tests/cases/sysdns.py +++ b/tests/cases/sysdns.py @@ -1,6 +1,6 @@ """The system's name servers and hosts file as the default resolver: with no nserver in a configuration, names in the hosts file are answered from -it, through the name cache; with nserver lines, the file is not used.""" +it; with nserver lines, or sysresolve (the system routines), it is not.""" import os import re @@ -81,3 +81,26 @@ def run(t): wait(t, other, "localhost") t.ne(["127.0.0.1"], t.dns_query(other, "localhost") or [], "with nserver, the hosts file is not used") + + # sysresolve: the system routines resolve names, and nothing is imported + # for dnspr to answer from + sysport, proxy, srv = t.free_port(), t.free_port(), t.free_port() + t.start("sysdns_sysresolve", f""" + log + flush + sysresolve + auth iponly + allow * + dnspr -p{sysport} + proxy -p{proxy} + flush + auth iponly + allow * + http echo * /echo** + httpsrv -p{srv} + """, ports=[proxy, srv]) + wait(t, sysport, "localhost") + t.ne(["127.0.0.1"], t.dns_query(sysport, "localhost") or [], + "with sysresolve, dnspr has no hosts file names") + t.eq(200, t.http(f"http://localhost:{srv}/echo", proxy=f"127.0.0.1:{proxy}").status, + "and names resolve through the system routines")