joshua/beats-server
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Added some comments and exceptions to handle errors

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This commit is contained in:
Joshua Moerman 2013-03-04 20:03:17 +01:00
parent 2f2a84d586
commit 99a89ec22f
2 changed files with 61 additions and 39 deletions
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9
main.cpp
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@ -15,15 +15,13 @@ struct User {
websockets::TestProtocol<User> default_protocol{
// connection established
[](User& user) -> int{
[](User& user){
user.index = uid++;
people_online[user.index] = "";
return 0;
},
// connection closed
[](User& user) -> int{
[](User& user){
people_online.erase(user.index);
return 0;
},
// write (will always come after receive)
[](User& user) -> std::string{
@ -32,9 +30,8 @@ websockets::TestProtocol<User> default_protocol{
return string_to_send;
},
// receive
[](User& user, std::string in) -> int{
[](User& user, std::string in){
people_online[user.index] = in;
return 0;
}
};

91
websockets.h
View file

@ -12,6 +12,23 @@
#include <lib/libwebsockets.h>
namespace websockets {
// Will be caught in the callback and program will continue to run (but connection will be closed)
struct runtime_error : public std::runtime_error {
int return_value;
runtime_error(const char * message, int return_value = -1)
: std::runtime_error(message)
, return_value(return_value)
{}
};
// Will never be caught (by us), and hence things will terminate
struct fatal_error : public std::runtime_error {
fatal_error(const char * message)
: std::runtime_error(message)
{}
};
struct Log {
Log(std::string const & name, int syslog_options, int debug_level){
setlogmask(LOG_UPTO (LOG_DEBUG));
@ -37,6 +54,7 @@ namespace websockets {
}
};
// Basic wrapper for the context pointer
struct Context {
std::unique_ptr<libwebsocket_context, decltype(libwebsocket_context_destroy)*> context;
@ -58,6 +76,7 @@ namespace websockets {
}
};
// Basic protocol to extend, already casts the void* to the actual type
template <typename T>
struct Protocol {
typedef T user_type;
@ -69,12 +88,16 @@ namespace websockets {
};
};
// 4-function Protocol, provide functions to handle establishment, closing, receiving and writing (follows receiving)
// To let the callback return something non-zero (in case of error), use websockets::runtime_error
template <typename T>
struct TestProtocol : public Protocol<T> {
std::function<int(T&)> establish_func;
std::function<int(T&)> close_func;
std::function<std::string(T&)> write_func;
std::function<int(T&, std::string)> receive_func;
struct TestProtocol {
typedef T user_type;
std::function<void(user_type&)> establish_func;
std::function<void(user_type&)> close_func;
std::function<std::string(user_type&)> write_func;
std::function<void(user_type&, std::string)> receive_func;
TestProtocol(decltype(establish_func) establish_func, decltype(close_func) close_func, decltype(write_func) write_func, decltype(receive_func) receive_func)
: establish_func(establish_func)
@ -83,41 +106,43 @@ namespace websockets {
, receive_func(receive_func)
{}
virtual int call(libwebsocket_context& context, libwebsocket& wsi, libwebsocket_callback_reasons reason, T& user, void *in, size_t len){
switch (reason) {
case LWS_CALLBACK_ESTABLISHED:
establish_func(user);
break;
case LWS_CALLBACK_CLOSED:
close_func(user);
break;
case LWS_CALLBACK_SERVER_WRITEABLE:{
std::string string_to_send = write_func(user);
// we need the extra bytes padding on both sides :(
unsigned char * buf = new unsigned char [LWS_SEND_BUFFER_PRE_PADDING + string_to_send.size() + LWS_SEND_BUFFER_POST_PADDING];
memcpy(&buf[LWS_SEND_BUFFER_PRE_PADDING], string_to_send.c_str(), string_to_send.size());
int n = libwebsocket_write(&wsi, &buf[LWS_SEND_BUFFER_PRE_PADDING], string_to_send.size(), LWS_WRITE_TEXT);
if (n < 0) {
lwsl_err("ERROR %d writing to socket, hanging up\n", n);
return 1;
int callback(libwebsocket_context* context, libwebsocket* wsi, libwebsocket_callback_reasons reason, void* user_ptr, void *in, size_t len){
user_type& user = *static_cast<user_type*>(user_ptr);
try{
switch (reason) {
case LWS_CALLBACK_ESTABLISHED:
establish_func(user);
break;
case LWS_CALLBACK_CLOSED:
close_func(user);
break;
case LWS_CALLBACK_SERVER_WRITEABLE:{
std::string string_to_send = write_func(user);
// we need the extra bytes padding on both sides :(
unsigned char * buf = new unsigned char [LWS_SEND_BUFFER_PRE_PADDING + string_to_send.size() + LWS_SEND_BUFFER_POST_PADDING];
memcpy(&buf[LWS_SEND_BUFFER_PRE_PADDING], string_to_send.c_str(), string_to_send.size());
int n = libwebsocket_write(wsi, &buf[LWS_SEND_BUFFER_PRE_PADDING], string_to_send.size(), LWS_WRITE_TEXT);
if (n < 0) throw runtime_error("Could not write", 1);
if (n < string_to_send.size()) throw runtime_error("Partial write", -1);
break;
}
if (n < string_to_send.size()) {
lwsl_err("Partial write\n");
return -1;
}
break;
case LWS_CALLBACK_RECEIVE:
receive_func(user, std::string((char*)in, len));
libwebsocket_callback_on_writable(context, wsi);
break;
default:
break;
}
case LWS_CALLBACK_RECEIVE:
receive_func(user, std::string((char*)in, len));
libwebsocket_callback_on_writable(&context, &wsi);
break;
default:
break;
} catch(runtime_error& e){
lwsl_err("Exception thrown: %s", e.what());
return e.return_value;
}
return 0;
}
};
// Some wrappers to easily create the list of protocols from structs of above kind.
#define WSprotocol_callback(protocol)\
[](libwebsocket_context *context, libwebsocket *wsi, libwebsocket_callback_reasons reason, void *user, void *in, size_t len)\
{return protocol.callback(context, wsi, reason, user, in, len);}