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rcm.cc
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rcm.cc
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#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <cstdio>
#include <cstring>
#include <unistd.h>
#include <memory>
#include <cassert>
#include <thread>
#include <sstream>
#include <string>
#include <vector>
#include <mutex>
#include <set>
#include <iostream>
using namespace std;
int listenTCP(uint16_t port)
{
int sockfd; // listen on sock_fd
struct addrinfo hints, *servinfo, *p;
//struct sockaddr_storage their_addr; // connector's address information
//socklen_t sin_size;
int yes=1;
//char s[INET6_ADDRSTRLEN];
int rv;
memset(&hints, 0, sizeof hints);
hints.ai_family = AF_UNSPEC;
hints.ai_socktype = SOCK_STREAM;
hints.ai_flags = AI_PASSIVE; // use my IP
string port_str = to_string(port);
if ((rv = getaddrinfo(NULL, port_str.c_str(), &hints, &servinfo)) != 0)
{
fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv));
exit(1);
}
// loop through all the results and bind to the first we can
for(p = servinfo; p != NULL; p = p->ai_next)
{
if ((sockfd = socket(p->ai_family, p->ai_socktype, p->ai_protocol)) == -1)
{
perror("socket() syscall");
continue;
}
if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(int)) == -1)
{
perror("setsockopt SO_REUSEADDR");
exit(1);
}
if (bind(sockfd, p->ai_addr, p->ai_addrlen) == -1)
{
close(sockfd);
perror("bind() syscall");
continue;
}
break;
}
freeaddrinfo(servinfo); // all done with this structure
if (p == NULL)
{
fprintf(stderr, "server: failed to bind\n");
exit(1);
}
if (listen(sockfd, 10) == -1) // allow connection backlog of up to 10
{
perror("listen() syscall");
exit(1);
}
printf("successfully bound to %d\n", port);
return sockfd;
}
// Basically like VAR=`cmd` in bash.
string runShellSync(const char* cmd)
{
char buffer[1024];
string ret;
unique_ptr<FILE, decltype(&pclose)> pipe(popen(cmd, "r"), pclose);
assert(pipe);
while (fgets(buffer, 1024, pipe.get()) != nullptr)
ret += buffer;
return ret;
}
vector<string> splitString(string s, char delim)
{
vector<string> result;
stringstream ss(s);
string item;
while (getline(ss, item, delim))
result.push_back(item);
return result;
}
// hack to filter chrome's duplicate requests
mutex g_mutex;
uint64_t g_next_nonce = 1;
uint64_t g_last_change_msse = 0;
set<uint64_t> g_nonces_used;
string buildPage()
{
string title, artist, filename;
string mpc_blob = runShellSync("mpc --format=\"%title%\\n%artist%\\n%file%\"");
auto info = splitString(mpc_blob, '\n');
string player_status;
if (auto vol_ind = mpc_blob.find("volume:"); vol_ind != string::npos)
player_status = mpc_blob.substr(vol_ind);
if (info.size() > 0)
title = info[0];
if (info.size() > 1)
artist = info[1];
if (info.size() > 2)
filename = info[2];
string display = title.empty() ? filename : (title + " by " + artist);
string cur_nonce;
{
const lock_guard<mutex> lock(g_mutex);
cur_nonce = std::to_string(g_next_nonce);
g_next_nonce++;
}
string page = "HTTP/1.1 200 OK\r\nCache-Control: no-cache\r\n\r\n";
page +=
"<head><meta charset=\"utf-8\"/><style>\nh1 {\n"
" font-size: 6em;\n"
"}\n</style></head><body>\n"
"Now playing:<br><b>"+display+"</b><br><br>"+player_status+"<br>\n"
"<h1>\n"
" <a href=\"RCMLAZYSTARTvoldnRCixMlz"+cur_nonce+"zlMxiCR\">. -- .</a> VOL <a href=\"RCMLAZYSTARTvolupRCixMlz"+cur_nonce+"zlMxiCR\">. + .</a>\n"
"</h1><br>\n"
"<h1>\n"
" <a href=\"RCMLAZYSTARTprevRCixMlz"+cur_nonce+"zlMxiCR\">. ⏮ .</a> . . <a href=\"RCMLAZYSTARTplpauseRCixMlz"+cur_nonce+"zlMxiCR\">. ⏯ .</a> . . <a href=\"RCMLAZYSTARTnextRCixMlz"+cur_nonce+"zlMxiCR\">. ⏭ .</a>\n"
"</h1><br>\n"
"<font size=\"+2\"><ul>\n";
vector<string> playlists = splitString(runShellSync("mpc lsplaylists | sort"), '\n');
for (const string& playlist : playlists)
{
page += "<li><a href=\"RCMLAZYSTARTplaylist/"+playlist+
"RCixMlz"+cur_nonce+"zlMxiCR\">"+playlist+"</a></li>\n";
}
page += "</ul></font></body>\n";
return page;
}
constexpr char kRedirect[] =
"HTTP/1.1 302 Found\r\n"
"Location: /RCMLAZYSTARTmainRCixMlz1zlMxiCR\r\n\r\n";
constexpr int kRedirectLen = strlen(kRedirect);
enum class Reaction { Nothing, Redirect, Display };
Reaction handleCommand(string cmd, uint64_t cmd_nonce)
{
cout << "handling command: " << cmd << endl;
if (cmd == "main")
return Reaction::Display;
if (cmd == "prev" || cmd == "plpause" || cmd == "next" || cmd == "voldn" ||
cmd == "volup" || cmd.find("playlist/") == 0)
{
const lock_guard<mutex> lock(g_mutex);
auto result = g_nonces_used.insert(cmd_nonce);
if (!result.second)
{
cout<<"rejecting "<<cmd<<" with nonce "<<cmd_nonce<<" as a duplicate"<<endl;
return Reaction::Redirect;
}
g_last_change_msse = std::chrono::duration_cast<std::chrono::milliseconds>(
std::chrono::system_clock::now().time_since_epoch()).count();
}
if (cmd == "prev")
runShellSync("mpc prev");
else if (cmd == "plpause")
runShellSync("mpc toggle");
else if (cmd == "next")
runShellSync("mpc next");
else if (cmd == "voldn")
runShellSync("mpc volume -10");
else if (cmd == "volup")
runShellSync("mpc volume +10");
else if (cmd.find("playlist/") == 0)
{
std::string playlist = cmd.substr(9);
if (playlist.find_first_not_of(
"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-_.")
== string::npos)
{
cout << "loading playlist: " << playlist << endl;
std::string runcmd = "mpc stop ; mpc clear ; mpc load ";
runcmd += playlist + " ; mpc play";
runShellSync(runcmd.c_str());
}
}
else
return Reaction::Nothing;
return Reaction::Redirect;
}
void httpSession(int fd)
{
assert(fd != -1);
char buf[1024];
int n = recv(fd, buf, 1023, 0);
if (n < 0)
perror("recv()");
else
{
buf[n] = 0;
const char* start = strstr(buf, "RCMLAZYSTART");
const char* end = strstr(buf, "RCixMlz");
const char* end2 = strstr(buf, "zlMxiCR");
if (start != 0 && end != 0 && end2 != 0)
{
uint64_t nonce = 0;
try { nonce = std::stoi(string(end+7, end2 - (end+7))); }
catch (const std::exception& e) {}
switch (handleCommand(string(start+12, (end) - (start+12)), nonce))
{
case Reaction::Nothing:
break;
case Reaction::Redirect:
send(fd, kRedirect, kRedirectLen, 0);
break;
case Reaction::Display:
string reply = buildPage();
send(fd, reply.c_str(), reply.length(), 0);
break;
}
}
}
shutdown(fd, SHUT_RDWR);
close(fd);
}
int main()
{
std::thread resetter([]()
{
while (true)
{
std::this_thread::sleep_for(std::chrono::hours(1));
const lock_guard<mutex> lock(g_mutex);
uint64_t now = std::chrono::duration_cast<std::chrono::milliseconds>(
std::chrono::system_clock::now().time_since_epoch()).count();
if (g_last_change_msse < now - 1000 * 60 * 59)
g_nonces_used.clear();
}
});
resetter.detach();
int listen_fd = listenTCP(10005);
while (true)
{
int fd = accept(listen_fd, nullptr, nullptr);
thread t(httpSession, fd);
t.detach();
}
close(listen_fd);
}