MDEV-8431 Feedback plugin needs an option for http proxy.

'feedback_http_proxy' system variable added to specify the
proxy server as host:port. Not a dynamic one.

plugin/feedback/feedback.cc

@@ -25,7 +25,7 @@ namespace feedback {
 char server_uid_buf[SERVER_UID_SIZE+1]; ///< server uid will be written here
 
 /* backing store for system variables */
-static char *server_uid= server_uid_buf, *url;
+static char *server_uid= server_uid_buf, *url, *http_proxy;
 char *user_info;
 ulong send_timeout, send_retry_wait;
 
@@ -272,7 +272,13 @@ static int init(void *p)
       if (*e == 0 || *e == ' ')
       {
         if (e > s && (urls[slot]= Url::create(s, e - s)))
+        {
+          if (urls[slot]->set_proxy(http_proxy,
+                                    http_proxy ? strlen(http_proxy) : 0))
+            sql_print_error("feedback plugin: invalid proxy '%s'",
+                            http_proxy ? http_proxy : "");
           slot++;
+        }
         else
         {
           if (e > s)
@@ -350,6 +356,10 @@ static MYSQL_SYSVAR_ULONG(send_timeout, send_timeout, PLUGIN_VAR_RQCMDARG,
 static MYSQL_SYSVAR_ULONG(send_retry_wait, send_retry_wait, PLUGIN_VAR_RQCMDARG,
        "Wait this many seconds before retrying a failed send.",
        NULL, NULL, 60, 1, 60*60*24, 1);
+static MYSQL_SYSVAR_STR(http_proxy, http_proxy,
+                        PLUGIN_VAR_READONLY | PLUGIN_VAR_RQCMDARG,
+       "Proxy server host:port.", NULL, NULL,0);
+
 
 static struct st_mysql_sys_var* settings[] = {
   MYSQL_SYSVAR(server_uid),
@@ -357,6 +367,7 @@ static struct st_mysql_sys_var* settings[] = {
   MYSQL_SYSVAR(url),
   MYSQL_SYSVAR(send_timeout),
   MYSQL_SYSVAR(send_retry_wait),
+  MYSQL_SYSVAR(http_proxy),
   NULL
 };
 

plugin/feedback/feedback.h

@@ -52,8 +52,14 @@ class Url {
   const char *url()   { return full_url.str; }
   size_t url_length() { return full_url.length; }
   virtual int send(const char* data, size_t data_length) =  0;
+  virtual int set_proxy(const char *proxy, size_t proxy_len)
+  {
+    return 0;
+  }
 
   static Url* create(const char *url, size_t url_length);
+  static int parse_proxy_server(const char *proxy_server, size_t proxy_length,
+                                LEX_STRING *host, LEX_STRING *port);
 };
 
 extern Url **urls;

plugin/feedback/url_base.cc

@@ -48,4 +48,50 @@ Url* Url::create(const char *url, size_t url_length)
   return self;
 }
 
+
+int Url::parse_proxy_server(const char *proxy_server, size_t proxy_length,
+                            LEX_STRING *host, LEX_STRING *port)
+{
+  const char *s;
+
+  host->length= 0;
+  if (proxy_server == NULL)
+    return 0;
+
+  for (; proxy_length > 0 && isspace(*proxy_server);
+         proxy_server++, proxy_length--) /* no-op */;
+
+  if (proxy_length == 0)
+    return 0;
+
+  for (s=proxy_server; *s && *s != ':'; s++) /* no-op */;
+
+  host->str= const_cast<char*>(proxy_server);
+  if ((host->length= s-proxy_server) == 0)
+    return 0;
+
+  port->length= 0;
+
+  if (*s == ':')
+  {
+    s++;
+    port->str= const_cast<char*>(s);
+    while (*s >= '0' && *s <= '9')
+    {
+      s++;
+      port->length++;
+    }
+  }
+
+  if (port->length == 0)
+  {
+    port->str= const_cast<char*>("80");
+    port->length= 2;
+  }
+
+  host->str= my_strndup(host->str, host->length, MYF(MY_WME));
+  port->str= my_strndup(port->str, port->length, MYF(MY_WME));
+  return 0;
+}
+
 } // namespace feedback

plugin/feedback/url_http.cc

@@ -38,20 +38,39 @@ class Url_http: public Url {
   protected:
   const LEX_STRING host, port, path;
   bool ssl;
+  LEX_STRING proxy_host, proxy_port;
+
+  int use_proxy()
+  {
+    return proxy_host.length;
+  }
 
   Url_http(LEX_STRING &url_arg, LEX_STRING &host_arg,
           LEX_STRING &port_arg, LEX_STRING &path_arg, bool ssl_arg) :
     Url(url_arg), host(host_arg), port(port_arg), path(path_arg), ssl(ssl_arg)
-    {}
+    {
+      proxy_host.length= 0;
+    }
   ~Url_http()
   {
     my_free(host.str);
     my_free(port.str);
     my_free(path.str);
+    set_proxy(0,0);
   }
 
   public:
   int send(const char* data, size_t data_length);
+  int set_proxy(const char *proxy, size_t proxy_len)
+  {
+    if (use_proxy())
+    {
+      my_free(proxy_host.str);
+      my_free(proxy_port.str);
+    }
+
+    return parse_proxy_server(proxy, proxy_len, &proxy_host, &proxy_port);
+  }
 
   friend Url* http_create(const char *url, size_t url_length);
 };
@@ -150,7 +169,9 @@ int Url_http::send(const char* data, size_t data_length)
   uint len= 0;
 
   addrinfo *addrs, *addr, filter= {0, AF_UNSPEC, SOCK_STREAM, 6, 0, 0, 0, 0};
-  int res= getaddrinfo(host.str, port.str, &filter, &addrs);
+  int res= use_proxy() ?
+    getaddrinfo(proxy_host.str, proxy_port.str, &filter, &addrs) :
+    getaddrinfo(host.str, port.str, &filter, &addrs);
 
   if (res)
   {
@@ -228,7 +249,11 @@ int Url_http::send(const char* data, size_t data_length)
   };
 
   len= my_snprintf(buf, sizeof(buf),
-                   "POST %s HTTP/1.0\r\n"
+                   use_proxy() ? "POST http://%s:%s/" : "POST ",
+                   host.str, port.str);
+
+  len+= my_snprintf(buf+len, sizeof(buf)-len,
+                    "%s HTTP/1.0\r\n"
                     "User-Agent: MariaDB User Feedback Plugin\r\n"
                     "Host: %s:%s\r\n"
                     "Accept: */*\r\n"