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hmchzb19

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Linuxer, ex IBMer. GNU https://hmchzb19.github.io/

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c socket真是痛苦的事情

分类： C/C++

2015-10-09 16:36:55

痛苦的想死，太复杂了，还是记录几个简单的玩具代码吧，这些例子都出自head first c.

点击(此处)折叠或打开

  1. #include <apue.h>
  2. #include <sys/socket.h>
  3. #include <arpa/inet.h>

  5. int main(int argc, char*argv[])
  6. {
  7.     char *advice[]={
  8.         "Take smaller bites\r\n",
  9.         "Go for the tight jeans. No they do NOT make you look fat.\r\n",
  10.         "One word: inappropriate\r\n",
  11.         "Just for today, be honest. Tell your boss what you *really* think\r\n",
  12.         "You might want to rethink that haircut\r\n"
  13.     };
  14.     int listener_d=socket(PF_INET,SOCK_STREAM,0);
  15.     
  16.     if(argc!=2)
  17.     {
  18.         printf("%s <port>\n",argv[0]);
  19.         exit(1);
  20.         }

  22.     struct sockaddr_in name;
  23.     name.sin_family=PF_INET;
  24.     name.sin_addr.s_addr=htonl(INADDR_ANY);
  25.     name.sin_port=(in_port_t)htons(atoi(argv[1]));
  26.     
  27.     int reuse=1;
  28.     if(setsockopt(listener_d,SOL_SOCKET,SO_REUSEADDR,(char *)&reuse,sizeof(int))==-1)
  29.         fputs("setsockopt() error\n",stderr);


  32.     if(bind(listener_d,(struct sockaddr*)&name,sizeof(name))==-1)
  33.         fputs("bind() error\n",stderr);

  35.     listen(listener_d,10);
  36.     puts("Waiting for connection");

  38.     while(1){
  39.         struct sockaddr_storage client_addr;
  40.         unsigned int address_size=sizeof(client_addr);
  41.         int connect_d=accept(listener_d,(struct sockaddr*)&client_addr,&address_size);
  42.         char *msg=advice[rand() % 5];

  44.         send(connect_d,msg,strlen(msg),0);
  45.         close(connect_d);
  46.     }
  47.     return 0;
  48. }
第一个例子比较简单，第二个多几个自定义函数，加上了信号的处理。

点击(此处)折叠或打开

  1. #include <apue.h>
  2. #include <sys/socket.h>
  3. #include <arpa/inet.h>
  4. #include <errno.h>

  6. int listener_d;

  8. void handle_shutdonw(int sig);
  9. int catch_signal(int sig,void(*handler)(int));
  10. int open_listener_socket();
  11. void bind_to_port(int socket,int port);
  12. int say(int socket,char *s);
  13. void error(char *msg);
  14. int read_in(int socket,char *buf,int len);

  16. int read_in(int socket,char *buf,int len)
  17. {
  18.     char *s=buf;
  19.     int slen=len;
  20.     int c=recv(socket,s,slen,0);
  21.     while((c>0)&&(s[c-1]!='\n')){
  22.         s+=c;
  23.         slen-=c;
  24.         c=recv(socket,s,slen,0);
  25.         }
  26.     if(c<0) //incase there is an error
  27.         return c;
  28.     else if(c==0)
  29.         buf[0]='\0'; //nothing read,send back an empty string
  30.     else
  31.         s[c-1]='\0';
  32.     return len-slen;
  33.     }

  35. void handle_shutdown(int sig)
  36. {
  37.     if(listener_d)
  38.         close(listener_d);

  40.     fprintf(stderr,"Bye!\n");
  41.     exit(0);
  42. }

  44. int catch_signal(int sig,void(*handler)(int))
  45. {
  46.     struct sigaction action;
  47.     action.sa_handler=handler;
  48.     sigemptyset(&action.sa_mask);
  49.     action.sa_flags=0;
  50.     return sigaction(sig,&action,NULL);
  51. }

  53. int open_listener_socket()
  54. {
  55.     int s=socket(PF_INET,SOCK_STREAM,0);
  56.     if(s==-1)
  57.         error("can't not open socket");

  59.     return s;
  60.     }

  62. void bind_to_port(int socket,int port)
  63. {
  64.     struct sockaddr_in name;
  65.     name.sin_family=PF_INET;
  66.     name.sin_addr.s_addr=htonl(INADDR_ANY);
  67.     name.sin_port=(in_port_t)htons(port);
  68.     int reuse=1;
  69.     if(setsockopt(socket,SOL_SOCKET,SO_REUSEADDR,(char*)&reuse,sizeof(int))==-1)
  70.         error("can't set the reuse option on the socket");

  72.     int c=bind(socket,(struct sockaddr*)&name,sizeof(name));
  73.     if(c==-1){
  74.         error("Can't bind to socket");
  75.         }
  76.     }

  78. int say(int socket,char *s) //send a string to a client
  79. {
  80.     int result=send(socket,s,strlen(s),0);
  81.     if(result==-1)
  82.         fprintf(stderr,"%s: %s\n","Error talking to the client",strerror(errno));
  83.     return result;
  84.     }

  86. void error(char *msg)
  87. {
  88.     fprintf(stderr,"%s: %s\n",msg,strerror(errno));
  89.     exit(1);
  90.     }



  94. int main(int argc, char *argv[])
  95. {
  96.     if(argc!=2){
  97.         fprintf(stderr,"%s <port>",argv[0]);
  98.         exit(1);
  99.         }

  101.     if(catch_signal(SIGINT,handle_shutdown)==-1)
  102.         error("can't set the interrupt handler");
  103.     
  104.     listener_d=open_listener_socket();
  105.     int port=atoi(argv[1]);
  106.     bind_to_port(listener_d,port);
  107.     if(listen(listener_d,10)==01)
  108.         error("can't listen");

  110.     struct sockaddr_storage client_addr;
  111.     unsigned int address_size=sizeof(client_addr);
  112.     puts("Waiting for connection");
  113.     char buf[255];

  115.     while(1)
  116.     {
  117.         int connect_d=accept(listener_d,(struct sockaddr*)&client_addr,&address_size);
  118.         if(connect_d==-1)
  119.             error("Can't open secondary socket");

  121.         if(say(connect_d,"Internet Knock-Knock Protocol Server\r\nVersion 1.0\r\nKnock!Knock!\r\n>")!=-1)
  122.         {
  123.             read_in(connect_d,buf,sizeof(buf));

  125.             if(strncasecmp("Who's there?",buf,12))
  126.                 say(connect_d,"You should say 'Who's ther?'!");
  127.             else{
  128.                 if(say(connect_d,"Osca\r\n> ")!=-1){
  129.                     read_in(connect_d,buf,sizeof(buf));
  130.                     if(strncasecmp("Oscar who?",buf,10))
  131.                         say(connect_d,"You should say 'Oscar who?'!\r\n");
  132.                     else
  133.                         say(connect_d,"Oscar silly question,you get a silly answer\r\n");
  134.                         }
  135.                     }
  136.                 }
  137.             close(connect_d);
  138.             }
  139.         return 0;
  140.         }
第三个例子则增加了一个fork() 和wait() ，即多进程的模型。

点击(此处)折叠或打开

  1. #include <apue.h>
  2. #include <sys/socket.h>
  3. #include <arpa/inet.h>
  4. #include <errno.h>

  6. int listener_d;

  8. void handle_shutdonw(int sig);
  9. int catch_signal(int sig,void(*handler)(int));
  10. int open_listener_socket();
  11. void bind_to_port(int socket,int port);
  12. int say(int socket,char *s);
  13. void error(char *msg);
  14. int read_in(int socket,char *buf,int len);

  16. int read_in(int socket,char *buf,int len)
  17. {
  18.     char *s=buf;
  19.     int slen=len;
  20.     int c=recv(socket,s,slen,0);
  21.     while((c>0)&&(s[c-1]!='\n')){
  22.         s+=c;
  23.         slen-=c;
  24.         c=recv(socket,s,slen,0);
  25.     }
  26.     if(c<0) //incase there is an error
  27.         return c;
  28.     else if(c==0)
  29.         buf[0]='\0'; //nothing read,send back an empty string
  30.     else
  31.         s[c-1]='\0';
  32.     return len-slen;
  33. }

  35. void handle_shutdown(int sig)
  36. {
  37.     if(listener_d)
  38.         close(listener_d);

  40.     fprintf(stderr,"Bye!\n");
  41.     exit(0);
  42. }

  44. int catch_signal(int sig,void(*handler)(int))
  45. {
  46.     struct sigaction action;
  47.     action.sa_handler=handler;
  48.     sigemptyset(&action.sa_mask);
  49.     action.sa_flags=0;
  50.     return sigaction(sig,&action,NULL);
  51. }

  53. int open_listener_socket()
  54. {
  55.     int s=socket(PF_INET,SOCK_STREAM,0);
  56.     if(s==-1)
  57.         error("can't not open socket");

  59.     return s;
  60. }

  62. void bind_to_port(int socket,int port)
  63. {
  64.     struct sockaddr_in name;
  65.     name.sin_family=PF_INET;
  66.     name.sin_addr.s_addr=htonl(INADDR_ANY);
  67.     name.sin_port=(in_port_t)htons(port);
  68.     int reuse=1;
  69.     if(setsockopt(socket,SOL_SOCKET,SO_REUSEADDR,(char*)&reuse,sizeof(int))==-1)
  70.         error("can't set the reuse option on the socket");

  72.     int c=bind(socket,(struct sockaddr*)&name,sizeof(name));
  73.     if(c==-1){
  74.         error("Can't bind to socket");
  75.     }
  76. }

  78. int say(int socket,char *s) //send a string to a client
  79. {
  80.     int result=send(socket,s,strlen(s),0);
  81.     if(result==-1)
  82.         fprintf(stderr,"%s: %s\n","Error talking to the client",strerror(errno));
  83.     return result;
  84. }

  86. void error(char *msg)
  87. {
  88.     fprintf(stderr,"%s: %s\n",msg,strerror(errno));
  89.     exit(1);
  90. }



  94. int main(int argc, char *argv[])
  95. {
  96.     if(argc!=2){
  97.         fprintf(stderr,"%s <port>",argv[0]);
  98.         exit(1);
  99.     }

  101.     if(catch_signal(SIGINT,handle_shutdown)==-1)
  102.         error("can't set the interrupt handler");

  104.     listener_d=open_listener_socket();
  105.     int port=atoi(argv[1]);
  106.     bind_to_port(listener_d,port);
  107.     if(listen(listener_d,10)==01)
  108.         error("can't listen");

  110.     struct sockaddr_storage client_addr;
  111.     unsigned int address_size=sizeof(client_addr);
  112.     puts("Waiting for connection");
  113.     char buf[255];

  115.     while(1)
  116.     {
  117.         int connect_d=accept(listener_d,(struct sockaddr*)&client_addr,&address_size);
  118.         if(connect_d==-1)
  119.             error("Can't open secondary socket");

  121.         if(fork()==0){ //child process
  122.             close(listener_d);
  123.             if(say(connect_d,"Internet Knock-Knock Protocol Server\r\nVersion 1.0\r\nKnock!Knock!\r\n>")!=-1)
  124.             {
  125.                 read_in(connect_d,buf,sizeof(buf));

  127.                 if(strncasecmp("Who's there?",buf,12))
  128.                     say(connect_d,"You should say 'Who's ther?'!");
  129.                 else{
  130.                     if(say(connect_d,"Osca\r\n> ")!=-1){
  131.                         read_in(connect_d,buf,sizeof(buf));
  132.                         if(strncasecmp("Oscar who?",buf,10))
  133.                             say(connect_d,"You should say 'Oscar who?'!\r\n");
  134.                         else
  135.                             say(connect_d,"Oscar silly question,you get a silly answer\r\n");
  136.                     }
  137.                 }
  138.             }
  139.             close(connect_d);
  140.             exit(0);
  141.         }
  142.         //wait(NULL);
  143.         close(connect_d);
  144.     }
  145.     return 0;
  146. }
#wait(NULL)是我自己加上去的，为了不产生zombie进程。否者只有主进程退出，子进程才会被init进程发现。
倒是让我想起来以前用nagios，经常会有zombie 进程的产生，估计是主进程少了waitpid 或者wait。除非主进程退出，zombie进程才会被init回收。




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