Add support for simple web server

Update Docker README.

README-docker.md

@@ -7,7 +7,7 @@ For running this docker, simply use the following commands:
 # run the container detached, forward internal port 25500 to host port 25500
 docker run -d --restart=always -p 25500:25500 tindy2013/subconverter:latest
 # then check its status
-curl http://localhost:25500
+curl http://localhost:25500/version
 # if you see `subconverter vx.x.x backend` then the container is up and running
 ```
 
@@ -37,6 +37,6 @@ docker build -t subconverter-custom:latest .
 # run the docker detached, forward internal port 25500 to host port 25500
 docker run -d --restart=always -p 25500:25500 subconverter-custom:latest
 # then check its status
-curl http://localhost:25500
+curl http://localhost:25500/version
 # if you see `subconverter vx.x.x backend` then the container is up and running
 ```

base/pref-new.yml

@@ -126,6 +126,7 @@ aliases:
 server:
   listen: 0.0.0.0
   port: 25500
+  serve_file_root: ""
 
 advanced:
   log_level: info

base/pref.ini

@@ -251,6 +251,9 @@ listen=0.0.0.0
 ;Port to bind on for Web Server
 port=25500
 
+;Root folder for web server, keep empty to disable
+serve_file_root=
+
 [advanced]
 log_level=info
 print_debug_info=false

src/interfaces.cpp

@@ -37,6 +37,9 @@ extern int gLogLevel;
 extern long gMaxAllowedDownloadSize;
 string_map gAliases;
 
+extern bool gServeFile;
+extern std::string gServeFileRoot;
+
 //global variables for template
 std::string gTemplatePath = "templates";
 string_map gTemplateVars;
@@ -837,6 +840,8 @@ void readYAMLConf(YAML::Node &node)
     {
         node["server"]["listen"] >> gListenAddress;
         node["server"]["port"] >> gListenPort;
+        node["server"]["serve_file_root"] >>= gServeFileRoot;
+        gServeFile = !gServeFileRoot.empty();
     }
 
     if(node["advanced"].IsDefined())
@@ -1088,6 +1093,8 @@ void readConf()
     ini.EnterSection("server");
     ini.GetIfExist("listen", gListenAddress);
     ini.GetIntIfExist("port", gListenPort);
+    gServeFileRoot = ini.Get("serve_file_root");
+    gServeFile = !gServeFileRoot.empty();
 
     ini.EnterSection("advanced");
     std::string log_level;

src/main.cpp

@@ -143,10 +143,12 @@ int main(int argc, char *argv[])
     if(gGeneratorMode)
         return simpleGenerator();
 
+    /*
     append_response("GET", "/", "text/plain", [](RESPONSE_CALLBACK_ARGS) -> std::string
     {
         return "subconverter " VERSION " backend\n";
     });
+    */
 
     append_response("GET", "/version", "text/plain", [](RESPONSE_CALLBACK_ARGS) -> std::string
     {

src/webserver_libevent.cpp

@@ -21,6 +21,72 @@
 extern std::string user_agent_str;
 std::atomic_bool SERVER_EXIT_FLAG(false);
 
+// file server
+bool gServeFile = false;
+std::string gServeFileRoot;
+
+struct MIME_type
+{
+    std::string extension;
+    std::string mimetype;
+};
+
+MIME_type mime_types[] = {{"html htm shtml","text/html"},
+                          {"css",           "text/css"},
+                          {"jpeg jpg",      "image/jpeg"},
+                          {"js",            "application/javascript"},
+                          {"txt",           "text/plain"},
+                          {"png",           "image/png"},
+                          {"ico",           "image/x-icon"},
+                          {"svg svgz",      "image/svg+xml"},
+                          {"woff",          "application/font-woff"},
+                          {"json",          "application/json"}};
+
+bool matchSpaceSeparatedList(const std::string& source, const std::string &target)
+{
+    string_size pos_begin = 0, pos_end, total = source.size();
+    while(pos_begin < total)
+    {
+        pos_end = source.find(' ', pos_begin);
+        if(pos_end == source.npos)
+            pos_end = total;
+        if(source.compare(pos_begin, pos_end - pos_begin, target) == 0)
+            return true;
+        pos_begin = pos_end + 1;
+    }
+    return false;
+}
+
+std::string checkMIMEType(const std::string filename)
+{
+    string_size name_begin = 0, name_end = 0;
+    name_begin = filename.rfind('/');
+    if(name_begin == filename.npos)
+        name_begin = 0;
+    name_end = filename.rfind('.');
+    if(name_end == filename.npos || name_end < name_begin || name_end == filename.size() - 1)
+        return "application/octet-stream";
+    std::string extension = filename.substr(name_end + 1);
+    for(MIME_type &x : mime_types)
+        if(matchSpaceSeparatedList(x.extension, extension))
+            return x.mimetype;
+    return "application/octet-stream";
+}
+
+int serveFile(const std::string &filename, std::string &content_type, std::string &return_data)
+{
+    std::string realname = gServeFileRoot + filename;
+    if(filename.compare("/") == 0)
+        realname += "index.html";
+    if(!fileExist(realname))
+        return 1;
+
+    return_data = fileGet(realname, false);
+    content_type = checkMIMEType(realname);
+    writeLog(0, "file-server: serving '" + filename + "' type '" + content_type + "'", LOG_LEVEL_INFO);
+    return 0;
+}
+
 struct responseRoute
 {
     std::string method;
@@ -83,6 +149,12 @@ static inline int process_request(Request &request, Response &response, std::str
         return 0;
     }
 
+    if(gServeFile)
+    {
+        if(request.method.compare("GET") == 0 && serveFile(request.url, response.content_type, return_data) == 0)
+            return 0;
+    }
+
     return -1;
 }