cpp-httplib

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

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

NOTE: This is a 'blocking' HTTP library. If you are looking for a 'non-blocking' library, this is not the one that you want.

Simple examples

Server

httplib::Server 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

httplib::Client cli("http://cpp-httplib-server.yhirose.repl.co");

auto res = cli.Get("/hi");

res->status; // 200
res->body;   // "Hello World!"

Try out the examples on Repl.it!

1. Run server at https://repl.it/@yhirose/cpp-httplib-server
2. Run client at https://repl.it/@yhirose/cpp-httplib-client

Server

#include <httplib.h>

int main(void)
{
  using namespace httplib;

  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 directory
auto 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:

Extension	MIME Type
txt	text/plain
html, htm	text/html
css	text/css
jpeg, jpg	image/jpg
png	image/png
gif	image/gif
svg	image/svg+xml
ico	image/x-icon
json	application/json
pdf	application/pdf
js	application/javascript
wasm	application/wasm
xml	application/xml
xhtml	application/xhtml+xml

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

Logging

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

Error handler

svr.set_error_handler([](const auto& 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");
});

'multipart/form-data' POST data

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

Receive content with Content receiver

svr.Post("/content_receiver",
  [&](const Request &req, Response &res, const ContentReader &content_reader) {
    if (req.is_multipart_form_data()) {
      MultipartFormDataItems files;
      content_reader(
        [&](const MultipartFormData &file) {
          files.push_back(file);
          return true;
        },
        [&](const char *data, size_t data_length) {
          files.back().content.append(data, data_length);
          return true;
        });
    } else {
      std::string body;
      content_reader([&](const char *data, size_t data_length) {
        body.append(data, data_length);
        return true;
      });
      res.set_content(body, "text/plain");
    }
  });

Send content with Content provider

const size_t DATA_CHUNK_SIZE = 4;

svr.Get("/stream", [&](const Request &req, Response &res) {
  auto data = new std::string("abcdefg");

  res.set_content_provider(
    data->size(), // Content length
    "text/plain", // Content type
    [data](size_t offset, size_t length, DataSink &sink) {
      const auto &d = *data;
      sink.write(&d[offset], std::min(length, DATA_CHUNK_SIZE));
      return true; // return 'false' if you want to cancel the process.
    },
    [data] { delete data; });
});

Without content length:

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

'Expect: 100-continue' handler

As default, the server sends 100 Continue response for Expect: 100-continue header.

// Send a '417 Expectation Failed' response.
svr.set_expect_100_continue_handler([](const Request &req, Response &res) {
  return 417;
});

// 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 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 = [] { return new ThreadPool(12); };

Override the default thread pool with yours

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

class YourThreadPoolTaskQueue : public TaskQueue {
public:
  YourThreadPoolTaskQueue(size_t n) {
    pool_.start_with_thread_count(n);
  }

  virtual void enqueue(std::function<void()> fn) override {
    pool_.enqueue(fn);
  }

  virtual void shutdown() override {
    pool_.shutdown_gracefully();
  }

private:
  YourThreadPool pool_;
};

svr.new_task_queue = [] {
  return new YourThreadPoolTaskQueue(12);
};

Client

#include <httplib.h>
#include <iostream>

int main(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();
    ...
  }
}

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");

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
};

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 Content receiver

std::string body;

auto res = cli.Get("/large-data",
  [&](const char *data, size_t data_length) {
    body.append(data, data_length);
    return true;
  });

std::string body;

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

Send content with 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);
    return true; // 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();
    return true; // return 'false' if you want to cancel the request.
  },
  "text/plain");

With Progress Callback

httplib::Client client(url, port);

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

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 specitic network interface

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

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

OpenSSL 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.

#define CPPHTTPLIB_OPENSSL_SUPPORT

httplib::SSLServer svr("./cert.pem", "./key.pem");

httplib::SSLClient cli("localhost", 1234); // or `httplib::Client cli("https://localhost:1234");`
cli.set_ca_cert_path("./ca-bundle.crt");
cli.enable_server_certificate_verification(true);

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.

Compression

The server can applie 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

Split httplib.h into .h and .cc

> python3 split.py
> ls out
httplib.h  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>

#define WIN32_LEAN_AND_MEAN
#include <Windows.h>
#include <httplib.h>

Note: Cygwin on Windows is not supported.

License

MIT license (© 2020 Yuji Hirose)

Special Thanks To

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