From 380e87ddfac09c59fddb48a300227c1f4ffe6ee0 Mon Sep 17 00:00:00 2001
From: Alexander Alashkin <alexander.alashkin@cesanta.com>
Date: Mon, 20 Mar 2017 09:43:05 +0000
Subject: [PATCH] Honor DNS server from DHCP
PUBLISHED_FROM=10772301ef115c31ada3521ff4235c33a421b782
---
docs/c-api/net.h/struct_mg_connect_opts.md | 1 +
docs/c-api/net.h/struct_mg_mgr.md | 1 +
docs/c-api/net.h/struct_mg_mgr_init_opts.md | 1 +
docs/c-api/resolv.h/intro.md | 1 +
docs/c-api/resolv.h/mg_set_nameserver.md | 10 ++++
.../resolv.h/struct_mg_resolve_async_opts.md | 2 +-
mongoose.c | 48 ++++++++++++-------
mongoose.h | 8 +++-
8 files changed, 54 insertions(+), 18 deletions(-)
create mode 100644 docs/c-api/resolv.h/mg_set_nameserver.md
diff --git a/docs/c-api/net.h/struct_mg_connect_opts.md b/docs/c-api/net.h/struct_mg_connect_opts.md
index f4ef502d7..f05bf25f4 100644
--- a/docs/c-api/net.h/struct_mg_connect_opts.md
+++ b/docs/c-api/net.h/struct_mg_connect_opts.md
@@ -8,6 +8,7 @@ signature: |
unsigned int flags; /* Extra connection flags */
const char **error_string; /* Placeholder for the error string */
struct mg_iface *iface; /* Interface instance */
+ const char *nameserver; /* DNS server to use, NULL for default */
#if MG_ENABLE_SSL
/*
* SSL settings.
diff --git a/docs/c-api/net.h/struct_mg_mgr.md b/docs/c-api/net.h/struct_mg_mgr.md
index dcc2b523d..63d946339 100644
--- a/docs/c-api/net.h/struct_mg_mgr.md
+++ b/docs/c-api/net.h/struct_mg_mgr.md
@@ -17,6 +17,7 @@ signature: |
#if MG_ENABLE_JAVASCRIPT
struct v7 *v7;
#endif
+ const char *nameserver; /* DNS server to use */
};
---
diff --git a/docs/c-api/net.h/struct_mg_mgr_init_opts.md b/docs/c-api/net.h/struct_mg_mgr_init_opts.md
index c0b658166..7db23de5b 100644
--- a/docs/c-api/net.h/struct_mg_mgr_init_opts.md
+++ b/docs/c-api/net.h/struct_mg_mgr_init_opts.md
@@ -7,6 +7,7 @@ signature: |
const struct mg_iface_vtable *main_iface;
int num_ifaces;
const struct mg_iface_vtable **ifaces;
+ const char *nameserver;
};
---
diff --git a/docs/c-api/resolv.h/intro.md b/docs/c-api/resolv.h/intro.md
index 3fc5fc069..f77184f9e 100644
--- a/docs/c-api/resolv.h/intro.md
+++ b/docs/c-api/resolv.h/intro.md
@@ -6,6 +6,7 @@ items:
- { name: mg_resolve_async.md }
- { name: mg_resolve_async_opt.md }
- { name: mg_resolve_from_hosts_file.md }
+ - { name: mg_set_nameserver.md }
- { name: struct_mg_resolve_async_opts.md }
---
diff --git a/docs/c-api/resolv.h/mg_set_nameserver.md b/docs/c-api/resolv.h/mg_set_nameserver.md
new file mode 100644
index 000000000..2e33c629c
--- /dev/null
+++ b/docs/c-api/resolv.h/mg_set_nameserver.md
@@ -0,0 +1,10 @@
+---
+title: "mg_set_nameserver()"
+decl_name: "mg_set_nameserver"
+symbol_kind: "func"
+signature: |
+ void mg_set_nameserver(struct mg_mgr *mgr, const char *nameserver);
+---
+
+Set default DNS server
+
diff --git a/docs/c-api/resolv.h/struct_mg_resolve_async_opts.md b/docs/c-api/resolv.h/struct_mg_resolve_async_opts.md
index 6c39e2f1a..8a836b9a0 100644
--- a/docs/c-api/resolv.h/struct_mg_resolve_async_opts.md
+++ b/docs/c-api/resolv.h/struct_mg_resolve_async_opts.md
@@ -4,7 +4,7 @@ decl_name: "struct mg_resolve_async_opts"
symbol_kind: "struct"
signature: |
struct mg_resolve_async_opts {
- const char *nameserver_url;
+ const char *nameserver;
int max_retries; /* defaults to 2 if zero */
int timeout; /* in seconds; defaults to 5 if zero */
int accept_literal; /* pseudo-resolve literal ipv4 and ipv6 addrs */
diff --git a/mongoose.c b/mongoose.c
index 3db5e8134..4780bdda1 100644
--- a/mongoose.c
+++ b/mongoose.c
@@ -2173,6 +2173,9 @@ void mg_mgr_init_opt(struct mg_mgr *m, void *user_data,
m->ifaces[i]->vtable->init(m->ifaces[i]);
}
}
+ if (opts.nameserver != NULL) {
+ m->nameserver = strdup(opts.nameserver);
+ }
DBG(("=================================="));
DBG(("init mgr=%p", m));
}
@@ -2230,6 +2233,8 @@ void mg_mgr_free(struct mg_mgr *m) {
}
MG_FREE(m->ifaces);
}
+
+ MG_FREE((char *) m->nameserver);
}
time_t mg_mgr_poll(struct mg_mgr *m, int timeout_ms) {
@@ -2742,6 +2747,7 @@ struct mg_connection *mg_connect_opt(struct mg_mgr *mgr, const char *address,
struct mg_resolve_async_opts o;
memset(&o, 0, sizeof(o));
o.dns_conn = &dns_conn;
+ o.nameserver = opts.nameserver;
if (mg_resolve_async_opt(nc->mgr, host, MG_DNS_A_RECORD, resolve_cb, nc,
o) != 0) {
MG_SET_PTRPTR(opts.error_string, "cannot schedule DNS lookup");
@@ -10692,10 +10698,6 @@ int mg_dns_reply_record(struct mg_dns_reply *reply,
#define MG_DEFAULT_NAMESERVER "8.8.8.8"
#endif
-static const char *mg_default_dns_server = "udp://" MG_DEFAULT_NAMESERVER ":53";
-
-MG_INTERNAL char mg_dns_server[256];
-
struct mg_resolve_async_request {
char name[1024];
int query;
@@ -10755,7 +10757,8 @@ static int mg_get_ip_address_of_nameserver(char *name, size_t name_len) {
if (comma != NULL) {
*comma = '\0';
}
- snprintf(name, name_len, "udp://%S:53", value);
+ /* %S will convert wchar_t -> char */
+ snprintf(name, name_len, "%S", value);
ret = 0;
RegCloseKey(hSub);
break;
@@ -10774,7 +10777,7 @@ static int mg_get_ip_address_of_nameserver(char *name, size_t name_len) {
for (ret = -1; fgets(line, sizeof(line), fp) != NULL;) {
unsigned int a, b, c, d;
if (sscanf(line, "nameserver %u.%u.%u.%u", &a, &b, &c, &d) == 4) {
- snprintf(name, name_len, "udp://%u.%u.%u.%u:53", a, b, c, d);
+ snprintf(name, name_len, "%u.%u.%u.%u", a, b, c, d);
ret = 0;
break;
}
@@ -10782,7 +10785,7 @@ static int mg_get_ip_address_of_nameserver(char *name, size_t name_len) {
(void) fclose(fp);
}
#else
- snprintf(name, name_len, "%s", mg_default_dns_server);
+ snprintf(name, name_len, "%s", MG_DEFAULT_NAMESERVER);
#endif /* _WIN32 */
return ret;
@@ -10910,7 +10913,12 @@ int mg_resolve_async_opt(struct mg_mgr *mgr, const char *name, int query,
struct mg_resolve_async_opts opts) {
struct mg_resolve_async_request *req;
struct mg_connection *dns_nc;
- const char *nameserver = opts.nameserver_url;
+ const char *nameserver = opts.nameserver;
+ char dns_server_buff[17], nameserver_url[26];
+
+ if (nameserver == NULL) {
+ nameserver = mgr->nameserver;
+ }
DBG(("%s %d %p", name, query, opts.dns_conn));
@@ -10929,17 +10937,18 @@ int mg_resolve_async_opt(struct mg_mgr *mgr, const char *name, int query,
req->timeout = opts.timeout ? opts.timeout : 5;
/* Lazily initialize dns server */
- if (nameserver == NULL && mg_dns_server[0] == '\0' &&
- mg_get_ip_address_of_nameserver(mg_dns_server, sizeof(mg_dns_server)) ==
- -1) {
- strncpy(mg_dns_server, mg_default_dns_server, sizeof(mg_dns_server));
- }
-
if (nameserver == NULL) {
- nameserver = mg_dns_server;
+ if (mg_get_ip_address_of_nameserver(dns_server_buff,
+ sizeof(dns_server_buff)) != -1) {
+ nameserver = dns_server_buff;
+ } else {
+ nameserver = MG_DEFAULT_NAMESERVER;
+ }
}
- dns_nc = mg_connect(mgr, nameserver, MG_CB(mg_resolve_async_eh, NULL));
+ snprintf(nameserver_url, sizeof(nameserver_url), "udp://%s:53", nameserver);
+
+ dns_nc = mg_connect(mgr, nameserver_url, MG_CB(mg_resolve_async_eh, NULL));
if (dns_nc == NULL) {
free(req);
return -1;
@@ -10952,6 +10961,13 @@ int mg_resolve_async_opt(struct mg_mgr *mgr, const char *name, int query,
return 0;
}
+void mg_set_nameserver(struct mg_mgr *mgr, const char *nameserver) {
+ free((char *) mgr->nameserver);
+ if (nameserver != NULL) {
+ mgr->nameserver = strdup(nameserver);
+ }
+}
+
#endif /* MG_ENABLE_ASYNC_RESOLVER */
#ifdef MG_MODULE_LINES
#line 1 "mongoose/src/coap.c"
diff --git a/mongoose.h b/mongoose.h
index 6fdf3bb16..6b37f4180 100644
--- a/mongoose.h
+++ b/mongoose.h
@@ -3274,6 +3274,7 @@ struct mg_mgr {
#if MG_ENABLE_JAVASCRIPT
struct v7 *v7;
#endif
+ const char *nameserver; /* DNS server to use */
};
/*
@@ -3368,6 +3369,7 @@ struct mg_mgr_init_opts {
const struct mg_iface_vtable *main_iface;
int num_ifaces;
const struct mg_iface_vtable **ifaces;
+ const char *nameserver;
};
/*
@@ -3538,6 +3540,7 @@ struct mg_connect_opts {
unsigned int flags; /* Extra connection flags */
const char **error_string; /* Placeholder for the error string */
struct mg_iface *iface; /* Interface instance */
+ const char *nameserver; /* DNS server to use, NULL for default */
#if MG_ENABLE_SSL
/*
* SSL settings.
@@ -5609,7 +5612,7 @@ typedef void (*mg_resolve_callback_t)(struct mg_dns_message *dns_message,
/* Options for `mg_resolve_async_opt`. */
struct mg_resolve_async_opts {
- const char *nameserver_url;
+ const char *nameserver;
int max_retries; /* defaults to 2 if zero */
int timeout; /* in seconds; defaults to 5 if zero */
int accept_literal; /* pseudo-resolve literal ipv4 and ipv6 addrs */
@@ -5621,6 +5624,9 @@ struct mg_resolve_async_opts {
int mg_resolve_async(struct mg_mgr *mgr, const char *name, int query,
mg_resolve_callback_t cb, void *data);
+/* Set default DNS server */
+void mg_set_nameserver(struct mg_mgr *mgr, const char *nameserver);
+
/*
* Resolved a DNS name asynchronously.
*
--
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