[Tarantool-patches] [PATCH v2 2/2] lua: return getaddrinfo() errors

[Roman Khabibov <roman.habibov@tarantool.org>]

Add getaddrinfo() errors into the several fuctions of socket. Now
getaddrinfo() can return a pair of values (nil and error message)
in case of error.

Closes #4138

@TarantoolBot document
Title: socket API changes

* socket.getaddrinfo()

Can return error message as second return value in case of
internal getaddrinfo() error.

Example:
tarantool> socket.getaddrinfo('non_exists_hostname', 3301)
---
- null
- 'getaddrinfo: nodename nor servname provided, or not known'
...

* socket.tcp_connect()

Can return socket.getaddrinfo() error message as second return
value.

Example:
tarantool> socket.tcp_connect('non_exists_hostname', 3301)
---
- null
- 'getaddrinfo: nodename nor servname provided, or not known'
...
---
 src/box/lua/net_box.lua   |  7 +++--
 src/lua/socket.c          | 16 +++++++++-
 src/lua/socket.lua        | 22 ++++++++++----
 test/app/socket.result    | 63 ++++++++++++++++++++++++++++++++++++---
 test/app/socket.test.lua  | 35 ++++++++++++++++++++--
 test/box/net.box.result   | 31 +++++++++++++++++++
 test/box/net.box.test.lua | 20 +++++++++++++
 7 files changed, 179 insertions(+), 15 deletions(-)

diff --git a/src/box/lua/net_box.lua b/src/box/lua/net_box.lua
index 3f611c027..8068a8637 100644
--- a/src/box/lua/net_box.lua
+++ b/src/box/lua/net_box.lua
@@ -154,9 +154,12 @@ local function next_id(id) return band(id + 1, 0x7FFFFFFF) end
 local function establish_connection(host, port, timeout)
     local timeout = timeout or DEFAULT_CONNECT_TIMEOUT
     local begin = fiber.clock()
-    local s = socket.tcp_connect(host, port, timeout)
+    local s, err = socket.tcp_connect(host, port, timeout)
     if not s then
-        return nil, errno.strerror(errno())
+        if not err then
+            return nil, errno.strerror(errno())
+        end
+        return nil, err
     end
     local msg = s:read({chunk = IPROTO_GREETING_SIZE},
                         timeout - (fiber.clock() - begin))
diff --git a/src/lua/socket.c b/src/lua/socket.c
index e75a8802e..ba683ad3a 100644
--- a/src/lua/socket.c
+++ b/src/lua/socket.c
@@ -775,6 +775,18 @@ lbox_getaddrinfo_result_wrapper(struct lua_State *L)
 	return 1;
 }
 
+/**
+ * Wrap coio_getaddrinfo() and call it. Push returned values onto
+ * @a L Lua stack.
+ *
+ * @param L Lua stack.
+ *
+ * @retval 1 Number of returned values by Lua function if
+ * coio_getaddrinfo() success.
+ * @retval 2 Number of returned values by Lua function if
+ * coio_getaddrinfo() is failed (first is nil, second is error
+ * message).
+ */
 static int
 lbox_socket_getaddrinfo(struct lua_State *L)
 {
@@ -817,7 +829,9 @@ lbox_socket_getaddrinfo(struct lua_State *L)
 
 	if (dns_res != 0) {
 		lua_pushnil(L);
-		return 1;
+		struct error *err = diag_get()->last;
+		lua_pushstring(L, err->errmsg);
+		return 2;
 	}
 
 	/* no results */
diff --git a/src/lua/socket.lua b/src/lua/socket.lua
index a334ad45b..ce6dab301 100644
--- a/src/lua/socket.lua
+++ b/src/lua/socket.lua
@@ -1041,9 +1041,12 @@ local function tcp_connect(host, port, timeout)
     end
     local timeout = timeout or TIMEOUT_INFINITY
     local stop = fiber.clock() + timeout
-    local dns = getaddrinfo(host, port, timeout, { type = 'SOCK_STREAM',
+    local dns, err = getaddrinfo(host, port, timeout, { type = 'SOCK_STREAM',
         protocol = 'tcp' })
-    if dns == nil or #dns == 0 then
+    if dns == nil then
+        return nil, err
+    end
+    if #dns == 0 then
         boxerrno(boxerrno.EINVAL)
         return nil
     end
@@ -1360,8 +1363,12 @@ local function lsocket_tcp_connect(self, host, port)
     -- This function is broken by design
     local ga_opts = { family = 'AF_INET', type = 'SOCK_STREAM' }
     local timeout = deadline - fiber.clock()
-    local dns = getaddrinfo(host, port, timeout, ga_opts)
-    if dns == nil or #dns == 0 then
+    local dns, err = getaddrinfo(host, port, timeout, ga_opts)
+    if dns == nil then
+        self._errno = boxerrno.EINVAL
+        return nil, err
+    end
+    if #dns == 0 then
         self._errno = boxerrno.EINVAL
         return nil, socket_error(self)
     end
@@ -1547,9 +1554,12 @@ local function lsocket_connect(host, port)
     if host == nil or port == nil then
         error("Usage: luasocket.connect(host, port)")
     end
-    local s = tcp_connect(host, port)
+    local s, err = tcp_connect(host, port)
     if not s then
-        return nil, boxerrno.strerror()
+        if not err then
+            return nil, boxerrno.strerror()
+        end
+        return nil, err
     end
     setmetatable(s, lsocket_tcp_client_mt)
     return s
diff --git a/test/app/socket.result b/test/app/socket.result
index 9f0ea0a5d..3f26bf2b0 100644
--- a/test/app/socket.result
+++ b/test/app/socket.result
@@ -941,10 +941,20 @@ sc:close()
 - true
 ...
 -- tcp_connect
--- test timeout
-socket.tcp_connect('127.0.0.1', 80, 0.00000000001)
+-- Test timeout. In this test, tcp_connect can return the second
+-- output value from internal.getaddrinfo (usually on Mac OS, but
+-- theoretically it can happen on Linux too). Sometimes
+-- getaddrinfo() is timed out, sometimes connect. On Linux however
+-- getaddrinfo is fast enough to never give timeout error in
+-- the case. So, there are two sources of timeout errors that are
+-- reported differently. This difference has appeared after
+-- gh-4138 patch.
+s, err = socket.tcp_connect('127.0.0.1', 80, 0.00000000001)
 ---
-- null
+...
+s == nil
+---
+- true
 ...
 -- AF_INET
 s = socket('AF_INET', 'SOCK_STREAM', 'tcp')
@@ -1595,7 +1605,7 @@ fio.stat(path) == nil
 { socket.tcp_connect('abrakadabra#123') == nil, errno.strerror() }
 ---
 - - true
-  - Invalid argument
+  - Input/output error
 ...
 -- wrong options for getaddrinfo
 socket.getaddrinfo('host', 'port', { type = 'WRONG' }) == nil and errno() == errno.EINVAL
@@ -2914,3 +2924,48 @@ srv:close()
 ---
 - true
 ...
+-- gh-4138 Check getaddrinfo() error from socket:connect() only.
+-- Error code and error message returned by getaddrinfo() depends
+-- on system's gai_strerror().
+test_run:cmd("setopt delimiter ';'")
+---
+- true
+...
+function check_err(err)
+    if err == 'getaddrinfo: nodename nor servname provided, or not known' or
+       err == 'getaddrinfo: Servname not supported for ai_socktype' or
+       err == 'getaddrinfo: Name or service not known' or
+       err == 'getaddrinfo: hostname nor servname provided, or not known' or
+       err == 'getaddrinfo: Temporary failure in name resolution' or
+       err == 'getaddrinfo: Name could not be resolved at this time' then
+        return true
+    end
+    return false
+end;
+---
+...
+test_run:cmd("setopt delimiter ''");
+---
+- true
+...
+s, err = socket.getaddrinfo('non_exists_hostname', 3301)
+---
+...
+check_err(err)
+---
+- true
+...
+s, err = socket.connect('non_exists_hostname', 3301)
+---
+...
+check_err(err)
+---
+- true
+...
+s, err = socket.tcp_connect('non_exists_hostname', 3301)
+---
+...
+check_err(err)
+---
+- true
+...
diff --git a/test/app/socket.test.lua b/test/app/socket.test.lua
index d1fe7ada6..c455d3ddb 100644
--- a/test/app/socket.test.lua
+++ b/test/app/socket.test.lua
@@ -300,8 +300,16 @@ sc:close()
 
 -- tcp_connect
 
--- test timeout
-socket.tcp_connect('127.0.0.1', 80, 0.00000000001)
+-- Test timeout. In this test, tcp_connect can return the second
+-- output value from internal.getaddrinfo (usually on Mac OS, but
+-- theoretically it can happen on Linux too). Sometimes
+-- getaddrinfo() is timed out, sometimes connect. On Linux however
+-- getaddrinfo is fast enough to never give timeout error in
+-- the case. So, there are two sources of timeout errors that are
+-- reported differently. This difference has appeared after
+-- gh-4138 patch.
+s, err = socket.tcp_connect('127.0.0.1', 80, 0.00000000001)
+s == nil
 
 -- AF_INET
 s = socket('AF_INET', 'SOCK_STREAM', 'tcp')
@@ -988,3 +996,26 @@ s:receive('*a')
 s:close()
 srv:close()
 
+-- gh-4138 Check getaddrinfo() error from socket:connect() only.
+-- Error code and error message returned by getaddrinfo() depends
+-- on system's gai_strerror().
+test_run:cmd("setopt delimiter ';'")
+function check_err(err)
+    if err == 'getaddrinfo: nodename nor servname provided, or not known' or
+       err == 'getaddrinfo: Servname not supported for ai_socktype' or
+       err == 'getaddrinfo: Name or service not known' or
+       err == 'getaddrinfo: hostname nor servname provided, or not known' or
+       err == 'getaddrinfo: Temporary failure in name resolution' or
+       err == 'getaddrinfo: Name could not be resolved at this time' then
+        return true
+    end
+    return false
+end;
+test_run:cmd("setopt delimiter ''");
+
+s, err = socket.getaddrinfo('non_exists_hostname', 3301)
+check_err(err)
+s, err = socket.connect('non_exists_hostname', 3301)
+check_err(err)
+s, err = socket.tcp_connect('non_exists_hostname', 3301)
+check_err(err)
diff --git a/test/box/net.box.result b/test/box/net.box.result
index e3dabf7d9..3e1ce6b11 100644
--- a/test/box/net.box.result
+++ b/test/box/net.box.result
@@ -3927,6 +3927,37 @@ test_run:grep_log('default', '00000040:.*')
 ---
 - null
 ...
+-- gh-4138 Check getaddrinfo() error from connect() only. Error
+-- code and error message returned by getaddrinfo() depends on
+-- system's gai_strerror().
+test_run:cmd("setopt delimiter ';'")
+---
+- true
+...
+function check_err(err)
+    if err == 'getaddrinfo: nodename nor servname provided, or not known' or
+       err == 'getaddrinfo: Servname not supported for ai_socktype' or
+       err == 'getaddrinfo: Name or service not known' or
+       err == 'getaddrinfo: hostname nor servname provided, or not known' or
+       err == 'getaddrinfo: Temporary failure in name resolution' or
+       err == 'getaddrinfo: Name could not be resolved at this time' then
+            return true
+    end
+    return false
+end;
+---
+...
+test_run:cmd("setopt delimiter ''");
+---
+- true
+...
+s = remote.connect('non_exists_hostname:3301')
+---
+...
+check_err(s['error'])
+---
+- true
+...
 box.cfg{log_level=log_level}
 ---
 ...
diff --git a/test/box/net.box.test.lua b/test/box/net.box.test.lua
index 8e65ff470..cad8754c3 100644
--- a/test/box/net.box.test.lua
+++ b/test/box/net.box.test.lua
@@ -1582,4 +1582,24 @@ test_run:wait_log('default', '00000030:.*', nil, 10)
 -- we expect nothing below, so don't wait
 test_run:grep_log('default', '00000040:.*')
 
+-- gh-4138 Check getaddrinfo() error from connect() only. Error
+-- code and error message returned by getaddrinfo() depends on
+-- system's gai_strerror().
+test_run:cmd("setopt delimiter ';'")
+function check_err(err)
+    if err == 'getaddrinfo: nodename nor servname provided, or not known' or
+       err == 'getaddrinfo: Servname not supported for ai_socktype' or
+       err == 'getaddrinfo: Name or service not known' or
+       err == 'getaddrinfo: hostname nor servname provided, or not known' or
+       err == 'getaddrinfo: Temporary failure in name resolution' or
+       err == 'getaddrinfo: Name could not be resolved at this time' then
+            return true
+    end
+    return false
+end;
+test_run:cmd("setopt delimiter ''");
+
+s = remote.connect('non_exists_hostname:3301')
+check_err(s['error'])
+
 box.cfg{log_level=log_level}
-- 
2.21.0 (Apple Git-122)