[PATCH v2] Add RES_OPTIONS support for resolv.conf options overriding

[PATCH v2] Add RES_OPTIONS support for resolv.conf options overriding

[Stefan Sedich]

Currently glibc supports using the RES_OPTIONS environment variable
to customize the resolv.conf options on a per-process basis, this
adds the same support to musl
---
 src/network/resolvconf.c | 49 ++++++++++++++++++++++++++++++------------------
 1 file changed, 31 insertions(+), 18 deletions(-)

diff --git a/src/network/resolvconf.c b/src/network/resolvconf.c
index 4c3e4c4b..a343392d 100644
--- a/src/network/resolvconf.c
+++ b/src/network/resolvconf.c
@@ -5,6 +5,30 @@
 #include <string.h>
 #include <netinet/in.h>
 
+void __parse_resolv_opts(struct resolvconf *conf, char *opts)
+{
+	char *p, *z;
+
+	p = strstr(opts, "ndots:");
+	if (p && isdigit(p[6])) {
+		p += 6;
+		unsigned long x = strtoul(p, &z, 10);
+		if (z != p) conf->ndots = x > 15 ? 15 : x;
+	}
+	p = strstr(opts, "attempts:");
+	if (p && isdigit(p[9])) {
+		p += 9;
+		unsigned long x = strtoul(p, &z, 10);
+		if (z != p) conf->attempts = x > 10 ? 10 : x;
+	}
+	p = strstr(opts, "timeout:");
+	if (p && (isdigit(p[8]) || p[8]=='.')) {
+		p += 8;
+		unsigned long x = strtoul(p, &z, 10);
+		if (z != p) conf->timeout = x > 60 ? 60 : x;
+	}
+}
+
 int __get_resolv_conf(struct resolvconf *conf, char *search, size_t search_sz)
 {
 	char line[256];
@@ -38,24 +62,7 @@ int __get_resolv_conf(struct resolvconf *conf, char *search, size_t search_sz)
 			continue;
 		}
 		if (!strncmp(line, "options", 7) && isspace(line[7])) {
-			p = strstr(line, "ndots:");
-			if (p && isdigit(p[6])) {
-				p += 6;
-				unsigned long x = strtoul(p, &z, 10);
-				if (z != p) conf->ndots = x > 15 ? 15 : x;
-			}
-			p = strstr(line, "attempts:");
-			if (p && isdigit(p[9])) {
-				p += 9;
-				unsigned long x = strtoul(p, &z, 10);
-				if (z != p) conf->attempts = x > 10 ? 10 : x;
-			}
-			p = strstr(line, "timeout:");
-			if (p && (isdigit(p[8]) || p[8]=='.')) {
-				p += 8;
-				unsigned long x = strtoul(p, &z, 10);
-				if (z != p) conf->timeout = x > 60 ? 60 : x;
-			}
+			__parse_resolv_opts(conf, line);
 			continue;
 		}
 		if (!strncmp(line, "nameserver", 10) && isspace(line[10])) {
@@ -89,5 +96,11 @@ no_resolv_conf:
 
 	conf->nns = nns;
 
+	char *res_opts_env;
+	if (!libc.secure) res_opts_env = getenv("RES_OPTIONS");
+	if (res_opts_env) {
+		__parse_resolv_opts(conf, res_opts_env);
+	}
+
 	return 0;
 }
-- 
2.11.0

Re: [PATCH v2] Add RES_OPTIONS support for resolv.conf options overriding

[Georgi Chorbadzhiyski]

On 4/25/17 8:02 PM, Stefan Sedich wrote:
> +	char *res_opts_env;
> +	if (!libc.secure) res_opts_env = getenv("RES_OPTIONS");
> +	if (res_opts_env) {

It seems to me that 'res_opts_env' is not guaranteed to be initialized
in case libc.secure is set.

> +		__parse_resolv_opts(conf, res_opts_env);
> +	}
> +
>  	return 0;
>  }

Re: [PATCH v2] Add RES_OPTIONS support for resolv.conf options overriding

[Stefan Sedich]

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On Tue, Apr 25, 2017 at 11:20 AM Georgi Chorbadzhiyski <gf@unixsol.org>
wrote:

> On 4/25/17 8:02 PM, Stefan Sedich wrote:
> > +     char *res_opts_env;
> > +     if (!libc.secure) res_opts_env = getenv("RES_OPTIONS");
> > +     if (res_opts_env) {
>
> It seems to me that 'res_opts_env' is not guaranteed to be initialized
> in case libc.secure is set.
>
> > +             __parse_resolv_opts(conf, res_opts_env);
> > +     }
> > +
> >       return 0;
> >  }
>

Will initializing res_opts_env to 0 be enough here?

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Re: [PATCH v2] Add RES_OPTIONS support for resolv.conf options overriding

[Georgi Chorbadzhiyski]

On 4/25/17 9:26 PM, Stefan Sedich wrote:
> On Tue, Apr 25, 2017 at 11:20 AM Georgi Chorbadzhiyski <gf@unixsol.org <mailto:gf@unixsol.org>> wrote:
> 
>     On 4/25/17 8:02 PM, Stefan Sedich wrote:
>     > +     char *res_opts_env;
>     > +     if (!libc.secure) res_opts_env = getenv("RES_OPTIONS");
>     > +     if (res_opts_env) {
> 
>     It seems to me that 'res_opts_env' is not guaranteed to be initialized
>     in case libc.secure is set.
> 
>     > +             __parse_resolv_opts(conf, res_opts_env);
>     > +     }
>     > +
>     >       return 0;
>     >  }
> 
> 
> Will initializing res_opts_env to 0 be enough here? 

I think

char *res_opts_env = NULL;

would do the trick.

Re: [PATCH v2] Add RES_OPTIONS support for resolv.conf options overriding

[Stefan Sedich]

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On Tue, Apr 25, 2017 at 12:04 PM Georgi Chorbadzhiyski <gf@unixsol.org>
wrote:

> On 4/25/17 9:26 PM, Stefan Sedich wrote:
> > On Tue, Apr 25, 2017 at 11:20 AM Georgi Chorbadzhiyski <gf@unixsol.org
> <mailto:gf@unixsol.org>> wrote:
> >
> >     On 4/25/17 8:02 PM, Stefan Sedich wrote:
> >     > +     char *res_opts_env;
> >     > +     if (!libc.secure) res_opts_env = getenv("RES_OPTIONS");
> >     > +     if (res_opts_env) {
> >
> >     It seems to me that 'res_opts_env' is not guaranteed to be
> initialized
> >     in case libc.secure is set.
> >
> >     > +             __parse_resolv_opts(conf, res_opts_env);
> >     > +     }
> >     > +
> >     >       return 0;
> >     >  }
> >
> >
> > Will initializing res_opts_env to 0 be enough here?
>
> I think
>
> char *res_opts_env = NULL;
>
> would do the trick.
>
>
Done deal thanks Georgi!

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