# HG changeset patch
# User Lukas Lihotzki <lukas@lihotzki.de>
# Date 1642618053 -3600
# Wed Jan 19 19:47:33 2022 +0100
# Node ID e9f06dc2d6a4a1aa61c15009b84ceedcaf5983b2
# Parent aeab41dfd2606dd36cabbf01f1472726e27e8aea
Add ipv4=off option in resolver like ipv6=off (ticket #1330).

IPv6-only hosts (ticket #1330) and upstreams with IPv6 bind address
(ticket #1535) need to disable resolving to IPv4 addresses.

Ticket #1330 mentions ipv4=off is the proper fix.

diff -r aeab41dfd260 -r e9f06dc2d6a4 src/core/ngx_resolver.c
--- a/src/core/ngx_resolver.c Mon Jan 17 17:05:12 2022 +0300
+++ b/src/core/ngx_resolver.c Wed Jan 19 19:47:33 2022 +0100
@@ -122,10 +122,13 @@
static ngx_int_t ngx_resolver_cmp_srvs(const void *one, const void *two);

#if (NGX_HAVE_INET6)
+#define ngx_ipv4_enabled(r) r->ipv4
static void ngx_resolver_rbtree_insert_addr6_value(ngx_rbtree_node_t *temp,
ngx_rbtree_node_t *node, ngx_rbtree_node_t *sentinel);
static ngx_resolver_node_t *ngx_resolver_lookup_addr6(ngx_resolver_t *r,
struct in6_addr *addr, uint32_t hash);
+#else
+#define ngx_ipv4_enabled(r) 1
#endif


@@ -175,6 +178,7 @@
ngx_queue_init(&r->addr_expire_queue);

#if (NGX_HAVE_INET6)
+ r->ipv4 = 1;
r->ipv6 = 1;

ngx_rbtree_init(&r->addr6_rbtree, &r->addr6_sentinel,
@@ -225,6 +229,23 @@
}

#if (NGX_HAVE_INET6)
+ if (ngx_strncmp(names[i].data, "ipv4=", 5) == 0) {
+
+ if (ngx_strcmp(&names[i].data[5], "on") == 0) {
+ r->ipv4 = 1;
+
+ } else if (ngx_strcmp(&names[i].data[5], "off") == 0) {
+ r->ipv4 = 0;
+
+ } else {
+ ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
+ "invalid parameter: %V", &names[i]);
+ return NULL;
+ }
+
+ continue;
+ }
+
if (ngx_strncmp(names[i].data, "ipv6=", 5) == 0) {

if (ngx_strcmp(&names[i].data[5], "on") == 0) {
@@ -273,6 +294,13 @@
}
}

+#if (NGX_HAVE_INET6)
+ if (!r->ipv4 && !r->ipv6) {
+ ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "both ipv4 and ipv6 disabled");
+ return NULL;
+ }
+#endif
+
if (n && r->connections.nelts == 0) {
ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "no name servers defined");
return NULL;
@@ -836,7 +864,7 @@
r->last_connection = 0;
}

- rn->naddrs = (u_short) -1;
+ rn->naddrs = ngx_ipv4_enabled(r) ? (u_short) -1 : 0;
rn->tcp = 0;
#if (NGX_HAVE_INET6)
rn->naddrs6 = r->ipv6 ? (u_short) -1 : 0;
@@ -3644,7 +3672,7 @@
len = sizeof(ngx_resolver_hdr_t) + nlen + sizeof(ngx_resolver_qs_t);

#if (NGX_HAVE_INET6)
- p = ngx_resolver_alloc(r, r->ipv6 ? len * 2 : len);
+ p = ngx_resolver_alloc(r, len * (r->ipv4 + r->ipv6));
#else
p = ngx_resolver_alloc(r, len);
#endif
@@ -3657,19 +3685,21 @@

#if (NGX_HAVE_INET6)
if (r->ipv6) {
- rn->query6 = p + len;
+ rn->query6 = p + len * r->ipv4;
}
#endif

query = (ngx_resolver_hdr_t *) p;

- ident = ngx_random();
-
- ngx_log_debug2(NGX_LOG_DEBUG_CORE, r->log, 0,
- "resolve: \"%V\" A %i", name, ident & 0xffff);
-
- query->ident_hi = (u_char) ((ident >> 8) & 0xff);
- query->ident_lo = (u_char) (ident & 0xff);
+ if (ngx_ipv4_enabled(r)) {
+ ident = ngx_random();
+
+ ngx_log_debug2(NGX_LOG_DEBUG_CORE, r->log, 0,
+ "resolve: \"%V\" A %i", name, ident & 0xffff);
+
+ query->ident_hi = (u_char) ((ident >> 8) & 0xff);
+ query->ident_lo = (u_char) (ident & 0xff);
+ }

/* recursion query */
query->flags_hi = 1; query->flags_lo = 0;
diff -r aeab41dfd260 -r e9f06dc2d6a4 src/core/ngx_resolver.h
--- a/src/core/ngx_resolver.h Mon Jan 17 17:05:12 2022 +0300
+++ b/src/core/ngx_resolver.h Wed Jan 19 19:47:33 2022 +0100
@@ -176,7 +176,8 @@
ngx_queue_t addr_expire_queue;

#if (NGX_HAVE_INET6)
- ngx_uint_t ipv6; /* unsigned ipv6:1; */
+ unsigned ipv4:1;
+ unsigned ipv6:1;
ngx_rbtree_t addr6_rbtree;
ngx_rbtree_node_t addr6_sentinel;
ngx_queue_t addr6_resend_queue;

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