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From b5fd71a0dfb8e7e32a46458abe701f7cd8ebc77b Mon Sep 17 00:00:00 2001
From: William Pitcock <nenolod@dereferenced.org>
Date: Fri, 30 Mar 2018 10:45:01 +0000
Subject: [PATCH] resolv.conf parser: concatenate multiple search domain lines
Programs such as Docker and Kubernetes write multiple domain search lines, such as
search serious-business.big-data.prod.foo.com
search big-data.prod.foo.com
search prod.foo.com
instead of
search serious-business.big-data.prod.foo.com big-data.prod.foo.com prod.foo.com
Accordingly, we concatenate the namelist together so that the search path is
not truncated.
(Sorry, not sorry, for ruining the "omg Alpine sucks at DNS" talk at Kubecon)
---
src/network/lookup_name.c | 2 +-
src/network/resolvconf.c | 7 ++++++-
2 files changed, 7 insertions(+), 2 deletions(-)
diff --git a/src/network/lookup_name.c b/src/network/lookup_name.c
index 209c20f0..c83c11c5 100644
--- a/src/network/lookup_name.c
+++ b/src/network/lookup_name.c
@@ -172,7 +172,7 @@ static int name_from_dns(struct address buf[static MAXADDRS], char canon[static
static int name_from_dns_search(struct address buf[static MAXADDRS], char canon[static 256], const char *name, int family)
{
- char search[256];
+ char search[2048];
struct resolvconf conf;
size_t l, dots;
char *p, *z;
diff --git a/src/network/resolvconf.c b/src/network/resolvconf.c
index 4c3e4c4b..72ed4082 100644
--- a/src/network/resolvconf.c
+++ b/src/network/resolvconf.c
@@ -9,6 +9,7 @@ int __get_resolv_conf(struct resolvconf *conf, char *search, size_t search_sz)
{
char line[256];
unsigned char _buf[256];
+ char *search_base = search;
FILE *f, _f;
int nns = 0;
@@ -74,9 +75,13 @@ int __get_resolv_conf(struct resolvconf *conf, char *search, size_t search_sz)
continue;
for (p=line+7; isspace(*p); p++);
size_t l = strlen(p);
+ ptrdiff_t m = search - search_base;
/* This can never happen anyway with chosen buffer sizes. */
- if (l >= search_sz) continue;
+ if (l + m >= search_sz) continue;
memcpy(search, p, l+1);
+ /* We concatenate the search list as domain1 domain2\0 */
+ search += l;
+ *search++ = ' ';
}
__fclose_ca(f);
--
2.16.2
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