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A C++ header-only HTTP/HTTPS server and client library

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cpp-httplib

A C++11 single-file header-only cross platform HTTP/HTTPS library.

It's extremely easy to setup. Just include the httplib.h file in your code!

NOTE: This library uses 'blocking' socket I/O. If you are looking for a library with 'non-blocking' socket I/O, this is not the one that you want.

Simple examples

Server (Multi-threaded)

#defineCPPHTTPLIB_OPENSSL_SUPPORT #include"path/to/httplib.h"// HTTP httplib::Server svr; // HTTPS httplib::SSLServer svr; svr.Get("/hi", [](const httplib::Request &, httplib::Response &res){res.set_content("Hello World!", "text/plain")}); svr.listen("0.0.0.0", 8080);

Client

#defineCPPHTTPLIB_OPENSSL_SUPPORT #include"path/to/httplib.h"// HTTP httplib::Client cli("http://cpp-httplib-server.yhirose.repl.co"); // HTTPS httplib::Client cli("https://cpp-httplib-server.yhirose.repl.co"); auto res = cli.Get("/hi"); res->status; res->body;

SSL Support

SSL support is available with CPPHTTPLIB_OPENSSL_SUPPORT. libssl and libcrypto should be linked.

NOTE: cpp-httplib currently supports only version 1.1.1 and 3.0.

#defineCPPHTTPLIB_OPENSSL_SUPPORT #include"path/to/httplib.h"// Server httplib::SSLServer svr("./cert.pem", "./key.pem"); // Client httplib::Client cli("https://localhost:1234"); // scheme + host httplib::SSLClient cli("localhost:1234"); // host// Use your CA bundle cli.set_ca_cert_path("./ca-bundle.crt"); // Disable cert verification cli.enable_server_certificate_verification(false);

Note: When using SSL, it seems impossible to avoid SIGPIPE in all cases, since on some operating systems, SIGPIPE can only be suppressed on a per-message basis, but there is no way to make the OpenSSL library do so for its internal communications. If your program needs to avoid being terminated on SIGPIPE, the only fully general way might be to set up a signal handler for SIGPIPE to handle or ignore it yourself.

Server

#include<httplib.h>intmain(void){usingnamespacehttplib; Server svr; svr.Get("/hi", [](const Request& req, Response& res){res.set_content("Hello World!", "text/plain")}); svr.Get(R"(/numbers/(\d+))", [&](const Request& req, Response& res){auto numbers = req.matches[1]; res.set_content(numbers, "text/plain")}); svr.Get("/body-header-param", [](const Request& req, Response& res){if (req.has_header("Content-Length")){auto val = req.get_header_value("Content-Length")} if (req.has_param("key")){auto val = req.get_param_value("key")} res.set_content(req.body, "text/plain")}); svr.Get("/stop", [&](const Request& req, Response& res){svr.stop()}); svr.listen("localhost", 1234)}

Post, Put, Delete and Options methods are also supported.

Bind a socket to multiple interfaces and any available port

int port = svr.bind_to_any_port("0.0.0.0"); svr.listen_after_bind();

Static File Server

// Mount / to ./www directoryauto ret = svr.set_mount_point("/", "./www"); if (!ret){// The specified base directory doesn't exist... } // Mount /public to ./www directory ret = svr.set_mount_point("/public", "./www"); // Mount /public to ./www1 and ./www2 directories ret = svr.set_mount_point("/public", "./www1"); // 1st order to search ret = svr.set_mount_point("/public", "./www2"); // 2nd order to search// Remove mount / ret = svr.remove_mount_point("/"); // Remove mount /public ret = svr.remove_mount_point("/public");
// User defined file extension and MIME type mappings svr.set_file_extension_and_mimetype_mapping("cc", "text/x-c"); svr.set_file_extension_and_mimetype_mapping("cpp", "text/x-c"); svr.set_file_extension_and_mimetype_mapping("hh", "text/x-h");

The followings are built-in mappings:

ExtensionMIME TypeExtensionMIME Type
csstext/cssmpgaaudio/mpeg
csvtext/csvwebaaudio/webm
txttext/plainwavaudio/wave
vtttext/vttotffont/otf
html, htmtext/htmlttffont/ttf
apngimage/apngwofffont/woff
avifimage/avifwoff2font/woff2
bmpimage/bmp7zapplication/x-7z-compressed
gifimage/gifatomapplication/atom+xml
pngimage/pngpdfapplication/pdf
svgimage/svg+xmlmjs, jsapplication/javascript
webpimage/webpjsonapplication/json
icoimage/x-iconrssapplication/rss+xml
tifimage/tifftarapplication/x-tar
tiffimage/tiffxhtml, xhtapplication/xhtml+xml
jpeg, jpgimage/jpegxsltapplication/xslt+xml
mp4video/mp4xmlapplication/xml
mpegvideo/mpeggzapplication/gzip
webmvideo/webmzipapplication/zip
mp3audio/mp3wasmapplication/wasm

File request handler

// The handler is called right before the response is sent to a client svr.set_file_request_handler([](const Request &req, Response &res){... });

NOTE: These static file server methods are not thread-safe.

Logging

svr.set_logger([](constauto& req, constauto& res){your_logger(req, res)});

Error handler

svr.set_error_handler([](constauto& req, auto& res){auto fmt = "<p>Error Status: <span style='color:red;'>%d</span></p>"; char buf[BUFSIZ]; snprintf(buf, sizeof(buf), fmt, res.status); res.set_content(buf, "text/html")});

Exception handler

The exception handler gets called if a user routing handler throws an error.

svr.set_exception_handler([](constauto& req, auto& res, std::exception_ptr ep){auto fmt = "<h1>Error 500</h1><p>%s</p>"; char buf[BUFSIZ]; try{std::rethrow_exception(ep)} catch (std::exception &e){snprintf(buf, sizeof(buf), fmt, e.what())} catch (...){// See the following NOTEsnprintf(buf, sizeof(buf), fmt, "Unknown Exception")} res.set_content(buf, "text/html"); res.status = 500});

NOTE: if you don't provide the catch (...) block for a rethrown exception pointer, an uncaught exception will end up causing the server crash. Be careful!

Pre routing handler

svr.set_pre_routing_handler([](constauto& req, auto& res){if (req.path == "/hello"){res.set_content("world", "text/html"); return Server::HandlerResponse::Handled} return Server::HandlerResponse::Unhandled});

Post routing handler

svr.set_post_routing_handler([](constauto& req, auto& res){res.set_header("ADDITIONAL_HEADER", "value")});

'multipart/form-data' POST data

svr.Post("/multipart", [&](constauto& req, auto& res){auto size = req.files.size(); auto ret = req.has_file("name1"); constauto& file = req.get_file_value("name1"); // file.filename;// file.content_type;// file.content; });

Receive content with a content receiver

svr.Post("/content_receiver", [&](const Request &req, Response &res, const ContentReader &content_reader){if (req.is_multipart_form_data()){// NOTE: `content_reader` is blocking until every form data field is read MultipartFormDataItems files; content_reader( [&](const MultipartFormData &file){files.push_back(file); returntrue}, [&](constchar *data, size_t data_length){files.back().content.append(data, data_length); returntrue})} else{std::string body; content_reader([&](constchar *data, size_t data_length){body.append(data, data_length); returntrue})} });

Send content with the content provider

constsize_t DATA_CHUNK_SIZE = 4; svr.Get("/stream", [&](const Request &req, Response &res){auto data = newstd::string("abcdefg"); res.set_content_provider( data->size(), // Content length"text/plain", // Content type [data](size_t offset, size_t length, DataSink &sink){constauto &d = *data; sink.write(&d[offset], std::min(length, DATA_CHUNK_SIZE)); returntrue; // return 'false' if you want to cancel the process. }, [data](bool success){delete data})});

Without content length:

svr.Get("/stream", [&](const Request &req, Response &res){res.set_content_provider( "text/plain", // Content type [&](size_t offset, DataSink &sink){if (/* there is still data */){std::vector<char> data; // prepare data... sink.write(data.data(), data.size())} else{sink.done(); // No more data } returntrue; // return 'false' if you want to cancel the process. })});

Chunked transfer encoding

svr.Get("/chunked", [&](const Request& req, Response& res){res.set_chunked_content_provider( "text/plain", [](size_t offset, DataSink &sink){sink.write("123", 3); sink.write("345", 3); sink.write("789", 3); sink.done(); // No more datareturntrue; // return 'false' if you want to cancel the process. } )});

'Expect: 100-continue' handler

By default, the server sends a 100 Continue response for an Expect: 100-continue header.

// Send a '417 Expectation Failed' response. svr.set_expect_100_continue_handler([](const Request &req, Response &res){return417});
// Send a final status without reading the message body. svr.set_expect_100_continue_handler([](const Request &req, Response &res){return res.status = 401});

Keep-Alive connection

svr.set_keep_alive_max_count(2); // Default is 5 svr.set_keep_alive_timeout(10); // Default is 5

Timeout

svr.set_read_timeout(5, 0); // 5 seconds svr.set_write_timeout(5, 0); // 5 seconds svr.set_idle_interval(0, 100000); // 100 milliseconds

Set maximum payload length for reading a request body

svr.set_payload_max_length(1024 * 1024 * 512); // 512MB

Server-Sent Events

Please see Server example and Client example.

Default thread pool support

ThreadPool is used as a default task queue, and the default thread count is 8, or std::thread::hardware_concurrency(). You can change it with CPPHTTPLIB_THREAD_POOL_COUNT.

If you want to set the thread count at runtime, there is no convenient way... But here is how.

svr.new_task_queue = []{returnnewThreadPool(12)};

Override the default thread pool with yours

You can supply your own thread pool implementation according to your need.

classYourThreadPoolTaskQueue : publicTaskQueue{public:YourThreadPoolTaskQueue(size_t n){pool_.start_with_thread_count(n)} virtualvoidenqueue(std::function<void()> fn) override{pool_.enqueue(fn)} virtualvoidshutdown() override{pool_.shutdown_gracefully()} private: YourThreadPool pool_}; svr.new_task_queue = []{returnnewYourThreadPoolTaskQueue(12)};

Client

#include<httplib.h> #include<iostream>intmain(void){httplib::Client cli("localhost", 1234); if (auto res = cli.Get("/hi")){if (res->status == 200){std::cout << res->body << std::endl} } else{auto err = res.error(); std::cout << "HTTP error: " << httplib::to_string(err) << std::endl} }

NOTE: Constructor with scheme-host-port string is now supported!

httplib::Client cli("localhost"); httplib::Client cli("localhost:8080"); httplib::Client cli("http://localhost"); httplib::Client cli("http://localhost:8080"); httplib::Client cli("https://localhost"); httplib::SSLClient cli("localhost");

Error code

Here is the list of errors from Result::error().

enum Error{Success = 0, Unknown, Connection, BindIPAddress, Read, Write, ExceedRedirectCount, Canceled, SSLConnection, SSLLoadingCerts, SSLServerVerification, UnsupportedMultipartBoundaryChars, Compression, ConnectionTimeout, };

GET with HTTP headers

httplib::Headers headers ={{"Accept-Encoding", "gzip, deflate" } }; auto res = cli.Get("/hi", headers);

or

cli.set_default_headers({{"Accept-Encoding", "gzip, deflate" } }); auto res = cli.Get("/hi");

POST

res = cli.Post("/post", "text", "text/plain"); res = cli.Post("/person", "name=john1&note=coder", "application/x-www-form-urlencoded");

POST with parameters

httplib::Params params; params.emplace("name", "john"); params.emplace("note", "coder"); auto res = cli.Post("/post", params);

or

httplib::Params params{{"name", "john" },{"note", "coder" } }; auto res = cli.Post("/post", params);

POST with Multipart Form Data

httplib::MultipartFormDataItems items ={{"text1", "text default", "", "" },{"text2", "aωb", "", "" },{"file1", "h\ne\n\nl\nl\no\n", "hello.txt", "text/plain" },{"file2", "{\n\"world\", true\n}\n", "world.json", "application/json" },{"file3", "", "", "application/octet-stream" }, }; auto res = cli.Post("/multipart", items);

PUT

res = cli.Put("/resource/foo", "text", "text/plain");

DELETE

res = cli.Delete("/resource/foo");

OPTIONS

res = cli.Options("*"); res = cli.Options("/resource/foo");

Timeout

cli.set_connection_timeout(0, 300000); // 300 milliseconds cli.set_read_timeout(5, 0); // 5 seconds cli.set_write_timeout(5, 0); // 5 seconds

Receive content with a content receiver

std::string body; auto res = cli.Get("/large-data", [&](constchar *data, size_t data_length){body.append(data, data_length); returntrue});
std::string body; auto res = cli.Get( "/stream", Headers(), [&](const Response &response){EXPECT_EQ(200, response.status); returntrue; // return 'false' if you want to cancel the request. }, [&](constchar *data, size_t data_length){body.append(data, data_length); returntrue; // return 'false' if you want to cancel the request. });

Send content with a content provider

std::string body = ...; auto res = cli.Post( "/stream", body.size(), [](size_t offset, size_t length, DataSink &sink){sink.write(body.data() + offset, length); returntrue; // return 'false' if you want to cancel the request. }, "text/plain");

Chunked transfer encoding

auto res = cli.Post( "/stream", [](size_t offset, DataSink &sink){sink.os << "chunked data 1"; sink.os << "chunked data 2"; sink.os << "chunked data 3"; sink.done(); returntrue; // return 'false' if you want to cancel the request. }, "text/plain");

With Progress Callback

httplib::Client client(url, port); // prints: 0 / 000 bytes => 50% completeauto res = cli.Get("/", [](uint64_t len, uint64_t total){printf("%lld / %lld bytes => %d%% complete\n", len, total, (int)(len*100/total)); returntrue; // return 'false' if you want to cancel the request. } );

progress

Authentication

// Basic Authentication cli.set_basic_auth("user", "pass"); // Digest Authentication cli.set_digest_auth("user", "pass"); // Bearer Token Authentication cli.set_bearer_token_auth("token");

NOTE: OpenSSL is required for Digest Authentication.

Proxy server support

cli.set_proxy("host", port); // Basic Authentication cli.set_proxy_basic_auth("user", "pass"); // Digest Authentication cli.set_proxy_digest_auth("user", "pass"); // Bearer Token Authentication cli.set_proxy_bearer_token_auth("pass");

NOTE: OpenSSL is required for Digest Authentication.

Range

httplib::Client cli("httpbin.org"); auto res = cli.Get("/range/32",{httplib::make_range_header({{1, 10}}) // 'Range: bytes=1-10' }); // res->status should be 206.// res->body should be "bcdefghijk".
httplib::make_range_header({{1, 10},{20, -1}}) // 'Range: bytes=1-10, 20-' httplib::make_range_header({{100, 199},{500, 599}}) // 'Range: bytes=100-199, 500-599' httplib::make_range_header({{0, 0},{-1, 1}}) // 'Range: bytes=0-0, -1'

Keep-Alive connection

httplib::Client cli("localhost", 1234); cli.Get("/hello"); // with "Connection: close" cli.set_keep_alive(true); cli.Get("/world"); cli.set_keep_alive(false); cli.Get("/last-request"); // with "Connection: close"

Redirect

httplib::Client cli("yahoo.com"); auto res = cli.Get("/"); res->status; // 301 cli.set_follow_location(true); res = cli.Get("/"); res->status; // 200

Use a specific network interface

NOTE: This feature is not available on Windows, yet.

cli.set_interface("eth0"); // Interface name, IP address or host name

Compression

The server can apply compression to the following MIME type contents:

  • all text types except text/event-stream
  • image/svg+xml
  • application/javascript
  • application/json
  • application/xml
  • application/xhtml+xml

Zlib Support

'gzip' compression is available with CPPHTTPLIB_ZLIB_SUPPORT. libz should be linked.

Brotli Support

Brotli compression is available with CPPHTTPLIB_BROTLI_SUPPORT. Necessary libraries should be linked. Please see https://github.com/google/brotli for more detail.

Compress request body on client

cli.set_compress(true); res = cli.Post("/resource/foo", "...", "text/plain");

Compress response body on client

cli.set_decompress(false); res = cli.Get("/resource/foo",{{"Accept-Encoding", "gzip, deflate, br"}}); res->body; // Compressed data

Use poll instead of select

select system call is used as default since it's more widely supported. If you want to let cpp-httplib use poll instead, you can do so with CPPHTTPLIB_USE_POLL.

Split httplib.h into .h and .cc

$ ./split.py -husage: split.py [-h] [-e EXTENSION] [-o OUT]This script splits httplib.h into .h and .cc parts.optional arguments: -h, --help show this help message and exit -e EXTENSION, --extension EXTENSION extension of the implementation file (default: cc) -o OUT, --out OUT where to write the files (default: out) $ ./split.pyWrote out/httplib.h and out/httplib.cc

NOTE

g++

g++ 4.8 and below cannot build this library since <regex> in the versions are broken.

Windows

Include httplib.h before Windows.h or include Windows.h by defining WIN32_LEAN_AND_MEAN beforehand.

#include<httplib.h> #include<Windows.h>
#defineWIN32_LEAN_AND_MEAN #include<Windows.h> #include<httplib.h>

Note: cpp-httplib officially supports only the latest Visual Studio. It might work with former versions of Visual Studio, but I can no longer verify it. Pull requests are always welcome for the older versions of Visual Studio unless they break the C++11 conformance.

Note: Windows 8 or lower, Visual Studio 2013 or lower, and Cygwin on Windows are not supported.

License

MIT license (© 2022 Yuji Hirose)

Special Thanks To

These folks made great contributions to polish this library to totally another level from a simple toy!

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A C++ header-only HTTP/HTTPS server and client library

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