From: Alexander Kanavin <alex@linutronix.de>
To: connman@lists.linux.dev, marcel@holtmann.org
Cc: Khem Raj <raj.khem@gmail.com>
Subject: [PATCH] gweb/gresolv.c: make use of res_ninit optional and subject to __RES
Date: Mon, 11 Mar 2024 12:09:18 +0100 [thread overview]
Message-ID: <20240311110918.1399173-1-alex@linutronix.de> (raw)
From: Khem Raj <raj.khem@gmail.com>
Not all libc implementation have those functions, and the way to determine
if they do is to check __RES which is explained in resolv.h thusly:
/*
* Revision information. This is the release date in YYYYMMDD format.
* It can change every day so the right thing to do with it is use it
* in preprocessor commands such as "#if (__RES > 19931104)". Do not
* compare for equality; rather, use it to determine whether your resolver
* is new enough to contain a certain feature.
*/
Indeed, it needs to be at least 19991006.
The portion of the patch that implements a fallback is ported from
Alpine Linux:
http://git.alpinelinux.org/cgit/aports/plain/testing/connman/libresolv.patch
---
gweb/gresolv.c | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)
diff --git a/gweb/gresolv.c b/gweb/gresolv.c
index 8101d718..9f1477c3 100644
--- a/gweb/gresolv.c
+++ b/gweb/gresolv.c
@@ -879,7 +879,9 @@ GResolv *g_resolv_new(int index)
resolv->index = index;
resolv->nameserver_list = NULL;
+#if (__RES >= 19991006)
res_ninit(&resolv->res);
+#endif
return resolv;
}
@@ -920,7 +922,9 @@ void g_resolv_unref(GResolv *resolv)
flush_nameservers(resolv);
+#if (__RES >= 19991006)
res_nclose(&resolv->res);
+#endif
g_free(resolv);
}
@@ -1024,6 +1028,7 @@ guint g_resolv_lookup_hostname(GResolv *resolv, const char *hostname,
debug(resolv, "hostname %s", hostname);
if (!resolv->nameserver_list) {
+#if (__RES >= 19991006)
int i;
for (i = 0; i < resolv->res.nscount; i++) {
@@ -1043,6 +1048,22 @@ guint g_resolv_lookup_hostname(GResolv *resolv, const char *hostname,
if (inet_ntop(family, sa_addr, buf, sizeof(buf)))
g_resolv_add_nameserver(resolv, buf, 53, 0);
}
+#else
+ FILE *f = fopen("/etc/resolv.conf", "r");
+ if (f) {
+ char line[256], *s;
+ int i;
+ while (fgets(line, sizeof(line), f)) {
+ if (strncmp(line, "nameserver", 10) || !isspace(line[10]))
+ continue;
+ for (s = &line[11]; isspace(s[0]); s++);
+ for (i = 0; s[i] && !isspace(s[i]); i++);
+ s[i] = 0;
+ g_resolv_add_nameserver(resolv, s, 53, 0);
+ }
+ fclose(f);
+ }
+#endif
if (!resolv->nameserver_list)
g_resolv_add_nameserver(resolv, "127.0.0.1", 53, 0);
--
2.39.2
reply other threads:[~2024-03-11 11:09 UTC|newest]
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