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I am trying to run the examples in C++ from the WebRTC source code, using the native API(not building) My Cmakelist is:

cmake_minimum_required(VERSION 3.5)
project(WebRTC)
include_directories("D:/Clion_Projects/src/api")
include_directories("D:/abseil-cpp")
include_directories("D:/CLion_Projects/src/")
add_executable(main examples/peerconnection/server/main.cc)

And the code is:

/*
 *  Copyright 2011 The WebRTC Project Authors. All rights reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */

#include <assert.h>
#include <stdio.h>
#include <stdlib.h>

#if defined(WEBRTC_POSIX)
#include <sys/select.h>
#endif

#include <time.h>

#include <string>
#include <vector>

#include "absl/flags/flag.h"
#include "absl/flags/parse.h"
#include "absl/flags/usage.h"
#include "examples/peerconnection/server/data_socket.h"
#include "examples/peerconnection/server/peer_channel.h"
#include "system_wrappers/include/field_trial.h"
#include "test/field_trial.h"


ABSL_FLAG(
        std::string,
        force_fieldtrials,
        "",
        "Field trials control experimental features. This flag specifies the field "
        "trials in effect. E.g. running with "
        "--force_fieldtrials=WebRTC-FooFeature/Enabled/ "
        "will assign the group Enabled to field trial WebRTC-FooFeature. Multiple "
        "trials are separated by \"/\"");
ABSL_FLAG(int, port, 8888, "default: 8888");

static const size_t kMaxConnections = (FD_SETSIZE - 2);

void HandleBrowserRequest(DataSocket *ds, bool *quit) {
    assert(ds && ds->valid());
    assert(quit);

    const std::string &path = ds->request_path();

    *quit = (path.compare("/quit") == 0);

    if (*quit) {
        ds->Send("200 OK", true, "text/html", "",
                 "<html><body>Quitting...</body></html>");
    } else if (ds->method() == DataSocket::OPTIONS) {
        // We'll get this when a browsers do cross-resource-sharing requests.
        // The headers to allow cross-origin script support will be set inside
        // Send.
        ds->Send("200 OK", true, "", "", "");
    } else {
        // Here we could write some useful output back to the browser depending on
        // the path.
        printf("Received an invalid request: %s\n", ds->request_path().c_str());
        ds->Send("500 Sorry", true, "text/html", "",
                 "<html><body>Sorry, not yet implemented</body></html>");
    }
}

int main(int argc, char *argv[]) {
    absl::SetProgramUsageMessage(
            "Example usage: ./peerconnection_server --port=8888\n");
    absl::ParseCommandLine(argc, argv);

    // InitFieldTrialsFromString stores the char*, so the char array must outlive
    // the application.
    const std::string force_field_trials = absl::GetFlag(FLAGS_force_fieldtrials);
    webrtc::field_trial::InitFieldTrialsFromString(force_field_trials.c_str());

    int port = absl::GetFlag(FLAGS_port);

    // Abort if the user specifies a port that is outside the allowed
    // range [1, 65535].
    if ((port < 1) || (port > 65535)) {
        printf("Error: %i is not a valid port.\n", port);
        return -1;
    }

    ListeningSocket listener;
    if (!listener.Create()) {
        printf("Failed to create server socket\n");
        return -1;
    } else if (!listener.Listen(port)) {
        printf("Failed to listen on server socket\n");
        return -1;
    }

    printf("Server listening on port %i\n", port);

    PeerChannel clients;
    typedef std::vector<DataSocket *> SocketArray;
    SocketArray sockets;
    bool quit = false;
    while (!quit) {
        fd_set socket_set;
        FD_ZERO(&socket_set);
        if (listener.valid())
            FD_SET(listener.socket(), &socket_set);

        for (SocketArray::iterator i = sockets.begin(); i != sockets.end(); ++i)
            FD_SET((*i)->socket(), &socket_set);

        struct timeval timeout = {10, 0};
        if (select(FD_SETSIZE, &socket_set, NULL, NULL, &timeout) == SOCKET_ERROR) {
            printf("select failed\n");
            break;
        }

        for (SocketArray::iterator i = sockets.begin(); i != sockets.end(); ++i) {
            DataSocket *s = *i;
            bool socket_done = true;
            if (FD_ISSET(s->socket(), &socket_set)) {
                if (s->OnDataAvailable(&socket_done) && s->request_received()) {
                    ChannelMember *member = clients.Lookup(s);
                    if (member || PeerChannel::IsPeerConnection(s)) {
                        if (!member) {
                            if (s->PathEquals("/sign_in")) {
                                clients.AddMember(s);
                            } else {
                                printf("No member found for: %s\n", s->request_path().c_str());
                                s->Send("500 Error", true, "text/plain", "",
                                        "Peer most likely gone.");
                            }
                        } else if (member->is_wait_request(s)) {
                            // no need to do anything.
                            socket_done = false;
                        } else {
                            ChannelMember *target = clients.IsTargetedRequest(s);
                            if (target) {
                                member->ForwardRequestToPeer(s, target);
                            } else if (s->PathEquals("/sign_out")) {
                                s->Send("200 OK", true, "text/plain", "", "");
                            } else {
                                printf("Couldn't find target for request: %s\n",
                                       s->request_path().c_str());
                                s->Send("500 Error", true, "text/plain", "",
                                        "Peer most likely gone.");
                            }
                        }
                    } else {
                        HandleBrowserRequest(s, &quit);
                        if (quit) {
                            printf("Quitting...\n");
                            FD_CLR(listener.socket(), &socket_set);
                            listener.Close();
                            clients.CloseAll();
                        }
                    }
                }
            } else {
                socket_done = false;
            }

            if (socket_done) {
                printf("Disconnecting socket\n");
                clients.OnClosing(s);
                assert(s->valid());  // Close must not have been called yet.
                FD_CLR(s->socket(), &socket_set);
                delete (*i);
                i = sockets.erase(i);
                if (i == sockets.end())
                    break;
            }
        }

        clients.CheckForTimeout();

        if (FD_ISSET(listener.socket(), &socket_set)) {
            DataSocket *s = listener.Accept();
            if (sockets.size() >= kMaxConnections) {
                delete s;  // sorry, that's all we can take.
                printf("Connection limit reached\n");
            } else {
                sockets.push_back(s);
                printf("New connection...\n");
            }
        }
    }

    for (SocketArray::iterator i = sockets.begin(); i != sockets.end(); ++i)
        delete (*i);
    sockets.clear();

    return 0;
}

But even after configuring the CmakeList I run into these errors:

Scanning dependencies of target main
[ 50%] Building CXX object CMakeFiles/main.dir/examples/peerconnection/server/main.cc.obj
[100%] Linking CXX executable main.exe
CMakeFiles\main.dir/objects.a(main.cc.obj): In function `HandleBrowserRequest(DataSocket*, bool*)':
D:/CLion_Projects/src/examples/peerconnection/server/main.cc:55: undefined reference to `DataSocket::Send(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, bool, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) const'
D:/CLion_Projects/src/examples/peerconnection/server/main.cc:61: undefined reference to `DataSocket::Send(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, bool, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) const'
D:/CLion_Projects/src/examples/peerconnection/server/main.cc:66: undefined reference to `DataSocket::Send(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, bool, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) const'
CMakeFiles\main.dir/objects.a(main.cc.obj): In function `main':
D:/CLion_Projects/src/examples/peerconnection/server/main.cc:72: undefined reference to `absl::SetProgramUsageMessage(absl::string_view)'
D:/CLion_Projects/src/examples/peerconnection/server/main.cc:74: undefined reference to `absl::ParseCommandLine(int, char**)'
D:/CLion_Projects/src/examples/peerconnection/server/main.cc:79: undefined reference to `webrtc::field_trial::InitFieldTrialsFromString(char const*)'
D:/CLion_Projects/src/examples/peerconnection/server/main.cc:91: undefined reference to `SocketBase::Create()'
D:/CLion_Projects/src/examples/peerconnection/server/main.cc:94: undefined reference to `ListeningSocket::Listen(unsigned short)'
D:/CLion_Projects/src/examples/peerconnection/server/main.cc:115: undefined reference to `__imp_select'
D:/CLion_Projects/src/examples/peerconnection/server/main.cc:123: undefined reference to `__WSAFDIsSet'
D:/CLion_Projects/src/examples/peerconnection/server/main.cc:124: undefined reference to `DataSocket::OnDataAvailable(bool*)'
D:/CLion_Projects/src/examples/peerconnection/server/main.cc:125: undefined reference to `PeerChannel::Lookup(DataSocket*) const'
D:/CLion_Projects/src/examples/peerconnection/server/main.cc:126: undefined reference to `PeerChannel::IsPeerConnection(DataSocket const*)'
D:/CLion_Projects/src/examples/peerconnection/server/main.cc:128: undefined reference to `DataSocket::PathEquals(char const*) const'
D:/CLion_Projects/src/examples/peerconnection/server/main.cc:129: undefined reference to `PeerChannel::AddMember(DataSocket*)'
D:/CLion_Projects/src/examples/peerconnection/server/main.cc:132: undefined reference to `DataSocket::Send(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, bool, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) const'
D:/CLion_Projects/src/examples/peerconnection/server/main.cc:135: undefined reference to `ChannelMember::is_wait_request(DataSocket*) const'
D:/CLion_Projects/src/examples/peerconnection/server/main.cc:139: undefined reference to `PeerChannel::IsTargetedRequest(DataSocket const*) const'
D:/CLion_Projects/src/examples/peerconnection/server/main.cc:141: undefined reference to `ChannelMember::ForwardRequestToPeer(DataSocket*, ChannelMember*)'
D:/CLion_Projects/src/examples/peerconnection/server/main.cc:142: undefined reference to `DataSocket::PathEquals(char const*) const'
D:/CLion_Projects/src/examples/peerconnection/server/main.cc:143: undefined reference to `DataSocket::Send(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, bool, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) const'
D:/CLion_Projects/src/examples/peerconnection/server/main.cc:147: undefined reference to `DataSocket::Send(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, bool, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) const'
D:/CLion_Projects/src/examples/peerconnection/server/main.cc:156: undefined reference to `SocketBase::Close()'
D:/CLion_Projects/src/examples/peerconnection/server/main.cc:157: undefined reference to `PeerChannel::CloseAll()'
D:/CLion_Projects/src/examples/peerconnection/server/main.cc:167: undefined reference to `PeerChannel::OnClosing(DataSocket*)'
D:/CLion_Projects/src/examples/peerconnection/server/main.cc:177: undefined reference to `PeerChannel::CheckForTimeout()'
D:/CLion_Projects/src/examples/peerconnection/server/main.cc:179: undefined reference to `__WSAFDIsSet'
D:/CLion_Projects/src/examples/peerconnection/server/main.cc:180: undefined reference to `ListeningSocket::Accept() const'
CMakeFiles\main.dir/objects.a(main.cc.obj):main.cc:(.data+0x0): undefined reference to `vtable for absl::flags_internal::FlagImpl'
CMakeFiles\main.dir/objects.a(main.cc.obj):D:/CLion_Projects/src/examples/peerconnection/server/main.cc:42: undefined reference to `vtable for absl::flags_internal::FlagImpl'
CMakeFiles\main.dir/objects.a(main.cc.obj): In function `SocketBase::~SocketBase()':
D:/CLion_Projects/src/examples/peerconnection/server/data_socket.h:40: undefined reference to `SocketBase::Close()'
CMakeFiles\main.dir/objects.a(main.cc.obj): In function `PeerChannel::~PeerChannel()':
D:/CLion_Projects/src/examples/peerconnection/server/peer_channel.h:75: undefined reference to `PeerChannel::DeleteAll()'
CMakeFiles\main.dir/objects.a(main.cc.obj): In function `absl::flags_internal::FlagRegistrar<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, true>::FlagRegistrar(absl::flags_internal::Flag<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >&, char const*)':
D:/abseil-cpp/absl/flags/internal/flag.h:726: undefined reference to `absl::flags_internal::RegisterCommandLineFlag(absl::CommandLineFlag&, char const*)'
CMakeFiles\main.dir/objects.a(main.cc.obj): In function `absl::flags_internal::FlagRegistrar<int, true>::FlagRegistrar(absl::flags_internal::Flag<int>&, char const*)':
D:/abseil-cpp/absl/flags/internal/flag.h:726: undefined reference to `absl::flags_internal::RegisterCommandLineFlag(absl::CommandLineFlag&, char const*)'
CMakeFiles\main.dir/objects.a(main.cc.obj): In function `std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > absl::UnparseFlag<int>(int const&)':
D:/abseil-cpp/absl/flags/marshalling.h:251: undefined reference to `absl::flags_internal::Unparse[abi:cxx11](int)'
CMakeFiles\main.dir/objects.a(main.cc.obj): In function `bool absl::flags_internal::InvokeParseFlag<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >(absl::string_view, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >*)':
D:/abseil-cpp/absl/flags/marshalling.h:195: undefined reference to `absl::flags_internal::AbslParseFlag(absl::string_view, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >*)'
CMakeFiles\main.dir/objects.a(main.cc.obj): In function `std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > absl::flags_internal::Unparse<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)':
D:/abseil-cpp/absl/flags/marshalling.h:208: undefined reference to `absl::flags_internal::AbslUnparseFlag[abi:cxx11](absl::string_view)'
CMakeFiles\main.dir/objects.a(main.cc.obj): In function `bool absl::flags_internal::InvokeParseFlag<int>(absl::string_view, int*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >*)':
D:/abseil-cpp/absl/flags/marshalling.h:195: undefined reference to `absl::flags_internal::AbslParseFlag(absl::string_view, int*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >*)'
CMakeFiles\main.dir/objects.a(main.cc.obj): In function `absl::flags_internal::Flag<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >::Get() const':
D:/abseil-cpp/absl/flags/internal/flag.h:618: undefined reference to `absl::flags_internal::FlagImpl::AssertValidType(void const*, std::type_info const* (*)()) const'
D:/abseil-cpp/absl/flags/internal/flag.h:622: undefined reference to `absl::flags_internal::FlagImpl::Read(void*) const'
CMakeFiles\main.dir/objects.a(main.cc.obj): In function `absl::flags_internal::Flag<int>::Get() const':
D:/abseil-cpp/absl/flags/internal/flag.h:618: undefined reference to `absl::flags_internal::FlagImpl::AssertValidType(void const*, std::type_info const* (*)()) const'
D:/abseil-cpp/absl/flags/internal/flag.h:622: undefined reference to `absl::flags_internal::FlagImpl::Read(void*) const'
collect2.exe: error: ld returned 1 exit status
mingw32-make.exe[3]: *** [CMakeFiles\main.dir\build.make:106: main.exe] Error 1
mingw32-make.exe[2]: *** [CMakeFiles\Makefile2:95: CMakeFiles/main.dir/all] Error 2
mingw32-make.exe[1]: *** [CMakeFiles\Makefile2:102: CMakeFiles/main.dir/rule] Error 2
mingw32-make.exe: *** [Makefile:137: main] Error 2

I don't understand why I am getting these errors, since I am running the example as is from the repo. Any help would be greatly appreciated!

guidingfox
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  • You didn't link with any libraries, so why would the symbols from those libraries be defined? The examples probably expect to be linked to a pre-existing WebRTC build. It also looks like you failed to link to Abseil too. – underscore_d Mar 05 '21 at 14:20
  • Does this answer your question? [What is an undefined reference/unresolved external symbol error and how do I fix it?](https://stackoverflow.com/questions/12573816/what-is-an-undefined-reference-unresolved-external-symbol-error-and-how-do-i-fix) – underscore_d Mar 05 '21 at 14:22
  • I did try linking with add_library() and set_target_properties() providing path to a precompiled WebRTC build. But the same error popping up – guidingfox Mar 05 '21 at 14:26
  • @underscore_d I don't think I understand that. I am new to C++... – guidingfox Mar 05 '21 at 14:27
  • 1
    If you are new to c++ I would not recommend diving straight into webrtc native code. It is a pain to compile and link everything together, but here's a starting point: https://webrtc.github.io/webrtc-org/native-code/development/ – lnogueir Mar 06 '21 at 16:51
  • Hey, @Inogueir Thank you for the reply! I'd seen this before, however my aim is to use the native API not build WebRTC from scratch. Is that possible? Could you tell me how I'll go about doing that? edit: Also this guide looks a bit outdated – guidingfox Mar 07 '21 at 17:06

0 Answers0