Add support for a fixed_irc_server configuration

This option lets the administrator choose a specific IRC server, and only
that server can be used with this biboumi instance.

In this mode, JIDs to use are changed like this:

- #chan%irc.example.com@biboumi.example.com      -> #chan@biboumi.example.com
- user!irc.example.com@biboumi.example.com       -> user!@biboumi.example.com
- #chan%irc.example.com@biboumi.example.com/Nick -> #chan@biboumi.example.com/Nick
- %irc.example.com@biboumi.example.com           -> no equivalent
- irc.example.com@biboumi.example.com            -> no equivalent

7 files changed, 194 insertions, 37 deletions

diff --git a/doc/biboumi.1.md b/doc/biboumi.1.md
index 18df220..9e95139 100644
--- a/doc/biboumi.1.md
+++ b/doc/biboumi.1.md
@@ -59,6 +59,20 @@ The configuration file uses a simple format of the form
   privileges), for example some administration ad-hoc commands will only be
   available to that JID.
 
+`fixed_irc_server`
+
+  If this option contains the hostname of an IRC server (for example
+  irc.example.org), then biboumi will enforce the connexion to that IRC
+  server only.  This means that a JID like "#chan@irc.biboumi.org" must be
+  used instead of "#chan%irc.example.org@irc.biboumi.org".  In that mode,
+  the virtual channel (see *Connect to an IRC server*) is not available and
+  you still need to use the ! separator to send message to an IRC user (for
+  example "foo!@biboumi.example.com" to send a message to foo), although the
+  in-room JID still work as expected ("#channel@biboumi.example.com/Nick").
+  This option can for example be used by an administrator that just wants to
+  let their users join their own IRC server using an XMPP client, but
+  without letting them join any other IRC servers on the internet.
+
 `log_file`
 
   A filename into which logs are written.  If none is provided, the logs are
diff --git a/src/bridge/bridge.cpp b/src/bridge/bridge.cpp
index fc00c8c..e312345 100644
--- a/src/bridge/bridge.cpp
+++ b/src/bridge/bridge.cpp
@@ -4,6 +4,7 @@
 #include <xmpp/xmpp_stanza.hpp>
 #include <irc/irc_message.hpp>
 #include <network/poller.hpp>
+#include <utils/empty_if_fixed_server.hpp>
 #include <utils/encoding.hpp>
 #include <utils/tolower.hpp>
 #include <logger/logger.hpp>
@@ -542,13 +543,13 @@ void Bridge::send_user_join(const std::string& hostname,
   std::string role;
   std::tie(role, affiliation) = get_role_affiliation_from_irc_mode(user_mode);
 
-  this->xmpp->send_user_join(chan_name + "%" + hostname, user->nick, user->host,
+  this->xmpp->send_user_join(chan_name + utils::empty_if_fixed_server("%" + hostname), user->nick, user->host,
                              affiliation, role, this->user_jid, self);
 }
 
 void Bridge::send_topic(const std::string& hostname, const std::string& chan_name, const std::string& topic)
 {
-  this->xmpp->send_topic(chan_name + "%" + hostname, this->make_xmpp_body(topic), this->user_jid);
+  this->xmpp->send_topic(chan_name + utils::empty_if_fixed_server("%" + hostname), this->make_xmpp_body(topic), this->user_jid);
 }
 
 std::string Bridge::get_own_nick(const Iid& iid)
@@ -585,7 +586,7 @@ void Bridge::send_affiliation_role_change(const Iid& iid, const std::string& tar
 
 void Bridge::send_iq_version_request(const std::string& nick, const std::string& hostname)
 {
-  this->xmpp->send_iq_version_request(nick + "!" + hostname, this->user_jid);
+  this->xmpp->send_iq_version_request(nick + "!" + utils::empty_if_fixed_server(hostname), this->user_jid);
 }
 
 void Bridge::send_xmpp_ping_request(const std::string& nick, const std::string& hostname,
@@ -594,7 +595,7 @@ void Bridge::send_xmpp_ping_request(const std::string& nick, const std::string&
   // Use revstr because the forwarded ping to target XMPP user must not be
   // the same that the request iq, but we also need to get it back easily
   // (revstr again)
-  this->xmpp->send_ping_request(nick + "!" + hostname, this->user_jid, utils::revstr(id));
+  this->xmpp->send_ping_request(nick + "!" + utils::empty_if_fixed_server(hostname), this->user_jid, utils::revstr(id));
 }
 
 void Bridge::set_preferred_from_jid(const std::string& nick, const std::string& full_jid)
diff --git a/src/irc/iid.cpp b/src/irc/iid.cpp
index 0bb991f..d4dc8ce 100644
--- a/src/irc/iid.cpp
+++ b/src/irc/iid.cpp
@@ -1,4 +1,5 @@
 #include <utils/tolower.hpp>
+#include <config/config.hpp>
 
 #include <irc/iid.hpp>
 
@@ -6,6 +7,16 @@ Iid::Iid(const std::string& iid):
   is_channel(false),
   is_user(false)
 {
+  const std::string fixed_irc_server = Config::get("fixed_irc_server", "");
+  if (fixed_irc_server.empty())
+    this->init(iid);
+  else
+    this->init_with_fixed_server(iid, fixed_irc_server);
+}
+
+
+void Iid::init(const std::string& iid)
+{
   const std::string::size_type sep = iid.find_first_of("%!");
   if (sep != std::string::npos)
     {
@@ -20,6 +31,29 @@ Iid::Iid(const std::string& iid):
     this->set_server(iid);
 }
 
+void Iid::init_with_fixed_server(const std::string& iid, const std::string& hostname)
+{
+  this->set_server(hostname);
+
+  const std::string::size_type sep = iid.find_first_of("%!");
+
+  // Without any separator, we consider that it's a channel
+  if (sep == std::string::npos)
+    {
+      this->is_channel = true;
+      this->set_local(iid);
+    }
+  else // A separator can be present to differenciate a channel from a user,
+       // but the part behind it (the hostname) is ignored
+    {
+      this->set_local(iid.substr(0, sep));
+      if (iid[sep] == '%')
+        this->is_channel = true;
+      else
+        this->is_user = true;
+    }
+}
+
 Iid::Iid(const Iid& other):
   is_channel(other.is_channel),
   is_user(other.is_user),
@@ -66,6 +100,14 @@ std::string Iid::get_sep() const
 namespace std {
   const std::string to_string(const Iid& iid)
   {
-    return iid.get_local() + iid.get_sep() + iid.get_server();
+    if (Config::get("fixed_irc_server", "").empty())
+      return iid.get_local() + iid.get_sep() + iid.get_server();
+    else
+      {
+        if (iid.get_sep() == "!")
+          return iid.get_local() + iid.get_sep();
+        else
+          return iid.get_local();
+      }
   }
 }
diff --git a/src/irc/iid.hpp b/src/irc/iid.hpp
index d30cbaa..91779b2 100644
--- a/src/irc/iid.hpp
+++ b/src/irc/iid.hpp
@@ -57,6 +57,10 @@ public:
   std::string get_sep() const;
 
 private:
+
+  void init(const std::string& iid);
+  void init_with_fixed_server(const std::string& iid, const std::string& hostname);
+
   std::string local;
   std::string server;
 
diff --git a/src/test.cpp b/src/test.cpp
index a4371b2..9fa2c99 100644
--- a/src/test.cpp
+++ b/src/test.cpp
@@ -303,38 +303,100 @@ int main()
   /**
    * IID parsing
    */
-  std::cout << color << "Testing IID parsing…" << reset << std::endl;
-  Iid iid1("foo!irc.example.org");
-  std::cout << std::to_string(iid1) << std::endl;
-  assert(std::to_string(iid1) == "foo!irc.example.org");
-  assert(iid1.get_local() == "foo");
-  assert(iid1.get_server() == "irc.example.org");
-  assert(!iid1.is_channel);
-  assert(iid1.is_user);
-
-  Iid iid2("#test%irc.example.org");
-  std::cout << std::to_string(iid2) << std::endl;
-  assert(std::to_string(iid2) == "#test%irc.example.org");
-  assert(iid2.get_local() == "#test");
-  assert(iid2.get_server() == "irc.example.org");
-  assert(iid2.is_channel);
-  assert(!iid2.is_user);
-
-  Iid iid3("%irc.example.org");
-  std::cout << std::to_string(iid3) << std::endl;
-  assert(std::to_string(iid3) == "%irc.example.org");
-  assert(iid3.get_local() == "");
-  assert(iid3.get_server() == "irc.example.org");
-  assert(iid3.is_channel);
-  assert(!iid3.is_user);
-
-  Iid iid4("irc.example.org");
-  std::cout << std::to_string(iid4) << std::endl;
-  assert(std::to_string(iid4) == "irc.example.org");
-  assert(iid4.get_local() == "");
-  assert(iid4.get_server() == "irc.example.org");
-  assert(!iid4.is_channel);
-  assert(!iid4.is_user);
+  {
+    std::cout << color << "Testing IID parsing…" << reset << std::endl;
+    Iid iid1("foo!irc.example.org");
+    std::cout << std::to_string(iid1) << std::endl;
+    assert(std::to_string(iid1) == "foo!irc.example.org");
+    assert(iid1.get_local() == "foo");
+    assert(iid1.get_server() == "irc.example.org");
+    assert(!iid1.is_channel);
+    assert(iid1.is_user);
+
+    Iid iid2("#test%irc.example.org");
+    std::cout << std::to_string(iid2) << std::endl;
+    assert(std::to_string(iid2) == "#test%irc.example.org");
+    assert(iid2.get_local() == "#test");
+    assert(iid2.get_server() == "irc.example.org");
+    assert(iid2.is_channel);
+    assert(!iid2.is_user);
+
+    Iid iid3("%irc.example.org");
+    std::cout << std::to_string(iid3) << std::endl;
+    assert(std::to_string(iid3) == "%irc.example.org");
+    assert(iid3.get_local() == "");
+    assert(iid3.get_server() == "irc.example.org");
+    assert(iid3.is_channel);
+    assert(!iid3.is_user);
+
+    Iid iid4("irc.example.org");
+    std::cout << std::to_string(iid4) << std::endl;
+    assert(std::to_string(iid4) == "irc.example.org");
+    assert(iid4.get_local() == "");
+    assert(iid4.get_server() == "irc.example.org");
+    assert(!iid4.is_channel);
+    assert(!iid4.is_user);
+
+    Iid iid5("nick!");
+    std::cout << std::to_string(iid5) << std::endl;
+    assert(std::to_string(iid5) == "nick!");
+    assert(iid5.get_local() == "nick");
+    assert(iid5.get_server() == "");
+    assert(!iid5.is_channel);
+    assert(iid5.is_user);
+
+    Iid iid6("##channel%");
+    std::cout << std::to_string(iid6) << std::endl;
+    assert(std::to_string(iid6) == "##channel%");
+    assert(iid6.get_local() == "##channel");
+    assert(iid6.get_server() == "");
+    assert(iid6.is_channel);
+    assert(!iid6.is_user);
+  }
+
+  {
+    std::cout << color << "Testing IID parsing with a fixed server configured…" << reset << std::endl;
+    // Now do the same tests, but with a configured fixed_irc_server
+    Config::set("fixed_irc_server", "fixed.example.com", false);
+
+    Iid iid1("foo!irc.example.org");
+    std::cout << std::to_string(iid1) << std::endl;
+    assert(std::to_string(iid1) == "foo!");
+    assert(iid1.get_local() == "foo");
+    assert(iid1.get_server() == "fixed.example.com");
+    assert(!iid1.is_channel);
+    assert(iid1.is_user);
+
+    Iid iid2("#test%irc.example.org");
+    std::cout << std::to_string(iid2) << std::endl;
+    assert(std::to_string(iid2) == "#test");
+    assert(iid2.get_local() == "#test");
+    assert(iid2.get_server() == "fixed.example.com");
+    assert(iid2.is_channel);
+    assert(!iid2.is_user);
+
+    // Note that it is impossible to adress the XMPP server directly, or to
+    // use the virtual channel, in that mode
+
+    // Iid iid3("%irc.example.org");
+    // Iid iid4("irc.example.org");
+
+    Iid iid5("nick!");
+    std::cout << std::to_string(iid5) << std::endl;
+    assert(std::to_string(iid5) == "nick!");
+    assert(iid5.get_local() == "nick");
+    assert(iid5.get_server() == "fixed.example.com");
+    assert(!iid5.is_channel);
+    assert(iid5.is_user);
+
+    Iid iid6("##channel%");
+    std::cout << std::to_string(iid6) << std::endl;
+    assert(std::to_string(iid6) == "##channel");
+    assert(iid6.get_local() == "##channel");
+    assert(iid6.get_server() == "fixed.example.com");
+    assert(iid6.is_channel);
+    assert(!iid6.is_user);
+  }
 
   return 0;
 }
diff --git a/src/utils/empty_if_fixed_server.cpp b/src/utils/empty_if_fixed_server.cpp
new file mode 100644
index 0000000..85fd86d
--- /dev/null
+++ b/src/utils/empty_if_fixed_server.cpp
@@ -0,0 +1,8 @@
+// #include <utils/empty_if_fixed_server.hpp>
+
+// #include <config/config.hpp>
+
+// namespace utils
+// {
+//   inline std::string empty_if_fixed_server(std::string&& str)
+// }
diff --git a/src/utils/empty_if_fixed_server.hpp b/src/utils/empty_if_fixed_server.hpp
new file mode 100644
index 0000000..8739fd9
--- /dev/null
+++ b/src/utils/empty_if_fixed_server.hpp
@@ -0,0 +1,26 @@
+#ifndef EMPTY_IF_FIXED_SERVER_HPP_INCLUDED
+#define EMPTY_IF_FIXED_SERVER_HPP_INCLUDED
+
+#include <string>
+
+#include <config/config.hpp>
+
+namespace utils
+{
+  inline std::string empty_if_fixed_server(std::string&& str)
+  {
+    if (!Config::get("fixed_irc_server", "").empty())
+      return {};
+    return str;
+  }
+
+  inline std::string empty_if_fixed_server(const std::string& str)
+  {
+    if (!Config::get("fixed_irc_server", "").empty())
+      return {};
+    return str;
+  }
+
+}
+
+#endif /* EMPTY_IF_FIXED_SERVER_HPP_INCLUDED */