前置作業：因為oversip必須從原始碼開始編譯，先安裝相關套件。一個個試誤列出來。
sudo yum install ruby
sudo yum install ruby-devel
sudo yum install cmake
sudo yum install gcc
sudo yum install g++
gem install oversip
出現錯誤
iobuffer.c:8:10: fatal error: rubyio.h: No such file or directory
8 | #include "rubyio.h"
| ^~~~~~~~~~
compilation terminated.
原因：ruby 2.2版之後把rubyio.h 更改結構為 ruby/io.h
解決方案：在/usr/include/ruby/backwards 新增rubyio.h檔案，內容如下：
#include "ruby/io.h"
繼續安裝gem install oversip
出現錯誤
em.cpp: In member function ‘bool EventMachine_t::_RunEpollOnce()’:
em.h:25:20: error: ‘rb_thread_select’ was not declared in this scope; did you mean ‘rb_thread_sleep’?
25 | #define EmSelect rb_thread_select
| ^~~~~~~~~~~~~~~~
原因：oversip的依賴套件：eventmachine-le 指定版本不支援ruby 2.2以上版本。
解決方案：查詢github上面的oversip已解決此問題(改用eventmachine 1.2)，改從github取得oversip最新版本。
git clone https://github.com/versatica/OverSIP.git
cd ~/OverSIP
gem build oversip (產生oversip-2.0.4.gem)
gem install oversip-2.0.4.gem
出現錯誤
Could not create Makefile due to some reason, probably lack of necessary
libraries and/or headers. Check the mkmf.log file for more details. You may
need configuration options.
stud.c:60:10: fatal error: ev.h: No such file or directory
60 | #include <ev.h>
| ^~~~~~
compilation terminated.
使用find尋找mkmf.log: find . -name 'mkmf.log'
mkmf.log 位置： .rvm/gems/ruby-2.7.2/gems/oversip-2.0.4/thirdparty/stud/mkmf.log （此為使用rvm之後的環境，供參考）
原因：ev.h的路徑錯誤。使用連結解決：
sudo ln -s /usr/include/libev/ev.h /usr/include/ev.h
還是出錯，原因相同。查詢發現ev.h不存在。
安裝libev-devel: sudo yum install libev-devel
出現錯誤
In file included from /usr/include/openssl/x509.h:36,
from stud.c:56:
/usr/include/openssl/rsa.h:301:28: note: declared here
301 | OSSL_DEPRECATEDIN_3_0 void RSA_free(RSA *r);
| ^~~~~~~~
stud.c: In function ‘end_handshake’:
stud.c:921:16: error: invalid use of incomplete typedef ‘SSL’ {aka ‘struct ssl_st’}
921 | if (ps->ssl->s3) {
| ^~
stud.c:922:16: error: invalid use of incomplete typedef ‘SSL’ {aka ‘struct ssl_st’}
922 | ps->ssl->s3->flags |= SSL3_FLAGS_NO_RENEGOTIATE_CIPHERS;
| ^~
make: *** [<builtin>: stud.o] Error 1
以下都是stud.c的編譯問題。解決方案：取得stud的最新版，並修正openssl相關的編譯錯誤。
cd OverSIP/thirdparty/stud
git clone https://github.com/bumptech/stud.git
tar cvzf stud.tar.gz stud/*
cd ~/OverSIP
gem build oversip (產生oversip-2.0.4.gem)
gem install oversip-2.0.4.gem
仍然出一樣的錯誤。
修改 OverSIP/thirdparty/stud/stud/stud.c #1063
ps->ssl->s3->flags |= SSL3_FLAGS_NO_RENEGOTIATE_CIPHERS;
->
SSL_set_options(ps->ssl, SSL3_FLAGS_NO_RENEGOTIATE_CIPHERS);
繼續安裝，出錯：
stud.c:551:14: error: invalid use of incomplete typedef ‘SSL_CTX’ {aka ‘struct ssl_ctx_s’}
551 | ctx->default_passwd_callback, ctx->default_passwd_callback_userdata);
| ^~
stud.c:551:44: error: invalid use of incomplete typedef ‘SSL_CTX’ {aka ‘struct ssl_ctx_s
查看stud.c, #551該行全文：
rsa = PEM_read_bio_RSAPrivateKey(bio, NULL,
ctx->default_passwd_callback, ctx->default_passwd_callback_userdata);
查資料發現openssl的新版不給直接存取SSL Context，必須使用存取函數處理。修改stud.c #551
rsa = PEM_read_bio_RSAPrivateKey(bio, NULL,
ctx->default_passwd_callback, ctx->default_passwd_callback_userdata);
->
rsa = PEM_read_bio_RSAPrivateKey(bio, NULL, SSL_CTX_get_default_passwd_cb
(ctx), SSL_CTX_get_default_passwd_cb_userdata(ctx));
避免重複處理，直接在OverSIP/thirdparty/stud/stud 執行make, 出錯。
stud.c:752:28: error: invalid use of incomplete typedef ‘X509_NAME_ENTRY’ {aka ‘struct X509_name_entry_st’}
752 | PUSH_CTX(x509_entry->value, ctx);
修改 stud.c #752
PUSH_CTX(x509_entry->value, ctx);
->
PUSH_CTX(X509_NAME_ENTRY_get_data(x509_entry), ctx);
make終於成功。正式進行gem的opersip安裝
cd ~/OverSIP
gem build oversip
gem install oversip-2.0.4.gem
安裝成功。
