Engine localization adaptation & Reconstruction notes

About daemons dup stderr problem ;

Log in and copy

      
      

       
       fd = open("/dev/null", O_RDWR);
       
       
 if (dup2(fd, STDIN_FILENO) == -1)
       
       
 if (dup2(fd, STDOUT_FILENO) == -1) 
       
       
    
       
       
#if xxx
       
       
     if (dup2(fd, STDERR_FILENO) == -1)
       
       
#else
       
       
    fd_log = open("pathlog", O_RDWR);
       
       
     if (dup2(fd_log, STDERR_FILENO) == -1)
       
       
#endif
       
       

       
       
if (fd > STDERR_FILENO) {
       
       
}
      
      
      
      

       
       
1.
       
       
2.
       
       
3.
       
       
4.
       
       
5.
       
       
6.
       
       
7.
       
       
8.
       
       
9.
       
       
10.
       
       
11.
       
       
12.
       
       
13.
      
      

take dup2(fd_log, stderr) still dup2(fd_null, stderr);

That is, the standard error is redirected to   Black hole or  log In file

look down man dup Result ：dup2() makes newfd be the copy of oldfd, closing newfd first if necessary,

 

 

Log in and copy

      
      

       
       NAME
       
       
       dup, dup2, dup3 - duplicate a file descriptor
       
       

       
       
SYNOPSIS
       
       
       #include <unistd.h>
       
       

       
       
       int dup(int oldfd);
       
       
       int dup2(int oldfd, int newfd);
       
       

       
       
       #define _GNU_SOURCE             /* See feature_test_macros(7) */
       
       
       #include <fcntl.h>              /* Obtain O_* constant definitions */
       
       
       #include <unistd.h>
       
       

       
       
       int dup3(int oldfd, int newfd, int flags);
       
       

       
       
DESCRIPTION
       
       
       These system calls create a copy of the file descriptor oldfd.
       
       

       
       
       dup() uses the lowest-numbered unused descriptor for the new descriptor.
       
       

       
       
       dup2() makes newfd be the copy of oldfd, closing newfd first if necessary, but note the following:
       
       

       
       
       *  If oldfd is not a valid file descriptor, then the call fails, and newfd is not closed.
       
       

       
       
       *  If oldfd is a valid file descriptor, and newfd has the same value as oldfd, then dup2() does nothing, and returns newfd.
       
       

       
       
       After  a  successful  return from one of these system calls, the old and new file descriptors may be used interchangeably.  They refer to the same open file description (see open(2)) and thus share file offset and file status flags; for
       
       
       example, if the file offset is modified by using lseek(2) on one of the descriptors, the offset is also changed for the other.
       
       

       
       
       The two descriptors do not share file descriptor flags (the close-on-exec flag).  The close-on-exec flag (FD_CLOEXEC; see fcntl(2)) for the duplicate descriptor is off.
       
       

       
       
       dup3() is the same as dup2(), except that:
       
       

       
       
       *  The caller can force the close-on-exec flag to be set for the new file descriptor by specifying O_CLOEXEC in flags.  See the description of the same flag in open(2) for reasons why this may be useful.
       
       

       
       
       *  If oldfd equals newfd, then dup3() fails with the error EINVAL.
      
      
      
      

       
       
1.
       
       
2.
       
       
3.
       
       
4.
       
       
5.
       
       
6.
       
       
7.
       
       
8.
       
       
9.
       
       
10.
       
       
11.
       
       
12.
       
       
13.
       
       
14.
       
       
15.
       
       
16.
       
       
17.
       
       
18.
       
       
19.
       
       
20.
       
       
21.
       
       
22.
       
       
23.
       
       
24.
       
       
25.
       
       
26.
       
       
27.
       
       
28.
       
       
29.
       
       
30.
       
       
31.
       
       
32.
       
       
33.
       
       
34.
       
       
35.
       
       
36.
      
      

 

 

 

Engine precautions : 

• Process name
• cpu binding
• Process resource settings (file_limit  core_limit  signal_mask)
• Time stamp setting ( Multi process / Multithreading )volatile  Prevent optimization
• Daemon
• signal processing   as well as coredump Handle
• log Set up
• Processing parameters
• Process unique instance
• Get rid of root Privilege
• Interprocess communication -socketpair  pipe  unix-socket  Shared memory （mmap munmap as well as shmget shmat shmctl)​ ​ Shared memory blog​​​ ​pipe-unix blog​​

 

Network middleware ：

  use  libevent libuv  Re encapsulation or   Write again in combination with your own business ？

Protocol analysis ：

 

Packing problem ：

• fakeroot jurisdiction ： Use fakeroot simulation root Authority executor , When packing , The owner of the file in the package must be root. Must be root  Permission to execute packaged commands , But you should avoid using... When making packages root jurisdiction . To solve this contradiction ,fakeroot It was developed . stay fakeroot Environment , Working with files is like using root Same as the operation file , however , In fact, the file permissions in the system are the same as the original permissions .

LD_PRELOAD=//usr/userpath/x86build/lib/libfakeroot.so    python build_packet.py

 

http proxy server （3-4-7 Layer of the agent ）- Network event library common component 、 kernel kernel drive Camera drive tcpip Network protocol stack 、netfilter、bridge Seems to have seen ！！！！ But he that doeth good Don't ask future -- Height and weight 180 Fat man