[C] 소켓 공부

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//실습 2번   #include <winsock2.h> #include <stdlib.h> #include <stdio.h>   #define BUFSIZE 512   //실습4번 int main(int argc, char* argv[]) {     WSADATA wsa;     if(WSAStartup(MAKEWORD(2,2),&wsa) != 0)         return -1;       char *ipaddr ="147.46.114.70";         printf("IP주소 = %s \n",ipaddr);       printf("변환후 = 0x%x\n",inet_addr(ipaddr));       IN_ADDR temp;     temp.s_addr = inet_addr(ipaddr);     printf("변환 = %s\n", inet_ntoa(temp));       WSACleanup();     return 0;   }   /* void err_quit(char *msg) ; void err_display(char *msg);   int main(int argc, char* argv[]) {     int retval;             WSADATA wsa;     if(WSAStartup(MAKEWORD(2,2), &wsa) != 0) return -1;             SOCKET listen_sock = socket(AF_INET, SOCK_STREAM, 0);     if(listen_sock == INVALID_SOCKET) err_quit("socket()");         SOCKADDR_IN serveraddr;     ZeroMemory(&serveraddr, sizeof(serveraddr));     serveraddr.sin_family = AF_INET;     serveraddr.sin_port = htons(9000);     serveraddr.sin_addr.s_addr = htonl(INADDR_ANY);     retval = bind(listen_sock, (SOCKADDR *)&serveraddr, sizeof(serveraddr));     if(retval == SOCKET_ERROR) err_quit("bind()");         retval = listen(listen_sock, SOMAXCONN);     if(retval == SOCKET_ERROR) err_quit("listen()");         SOCKET client_sock;     SOCKADDR_IN clientaddr;     int addrlen;     char buf[BUFSIZE+1];       while(1) {           addrlen = sizeof(clientaddr);         client_sock = accept(listen_sock, (SOCKADDR *)&clientaddr, &addrlen);         if(client_sock == INVALID_SOCKET) {             err_display("accept()");             continue;         }         printf("\n[TCP 서버] 클라이언트접속: IP 주소=%s, 포트、번호=%d\n",             inet_ntoa(clientaddr.sin_addr), ntohs(clientaddr.sin_port));             while(1) {             retval = recv(client_sock, buf, BUFSIZE, 0);             if(retval == SOCKET_ERROR) {                 err_display("recv()");                 break;             }             else if(retval == 0) {                 break;             }             else {                 buf[retval] = '\0';                 printf("%s", buf);             }                     //보내기         retval = send(client_sock, strupr(buf), BUFSIZE, 0);         if( retval== SOCKET_ERROR){             err_display("send()");             break;         }         printf("[TCP 클라이언트] %d 바이트를 보냈습니다.\n",retval);         }         closesocket(client_sock);         printf("\n[TCP 서버클라이언트 종료: IP 주소=%s, 포트번호=%d\n",               inet_ntoa(clientaddr.sin_addr), ntohs(clientaddr.sin_port));     }       closesocket(listen_sock);     WSACleanup();     return 0; }   void err_quit(char *msg) {     LPVOID ipMsgBuf;     FormatMessage(         FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM, NULL,         WSAGetLastError(),MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),         (LPTSTR)&ipMsgBuf,0,NULL);     MessageBox(NULL, (LPCTSTR)ipMsgBuf, msg, MB_ICONERROR);     LocalFree(ipMsgBuf);     exit(-1); }   void err_display(char *msg) {     LPVOID ipMsgBuf;     FormatMessage(         FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM, NULL,         WSAGetLastError(),MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),         (LPTSTR)&ipMsgBuf,0,NULL);     printf("[%s] %s", msg, (LPCTSTR)ipMsgBuf);     LocalFree(ipMsgBuf); }*/ ////////////////////////// /*   #include <stdio.h> #include <stdlib.h> #include <winsock2.h>   #define BUFSIZE 512   int recvn(SOCKET s, char *buf, int len, int flags); void err_quit(char *msg); void err_display(char *msg);   int main(int argc, char* argv[]) {     int retval;       WSADATA wsa;     if(WSAStartup(MAKEWORD(2,2),& wsa) !=0)         return -1;       SOCKET sock = socket(AF_INET, SOCK_STREAM, 0);     if(sock == INVALID_SOCKET) err_quit("socket()");       SOCKADDR_IN serveraddr;     ZeroMemory(&serveraddr, sizeof(serveraddr));     serveraddr.sin_family = AF_INET;r     serveraddr.sin_port = htons(9000);     serveraddr.sin_addr.s_addr = inet_addr("127.0.0.1");     retval - connect(sock, (SOCKADDR *)&serveraddr, sizeof(serveraddr));     if(retval == SOCKET_ERROR) err_quit("connect()");       char buf[BUFSIZE+1];     int len;       while(1)     {         ZeroMemory(buf, sizeof(buf));         printf("\n[보낼 테이터]");         if(fgets(buf, BUFSIZE+1, stdin) == NULL)             break;           // \n 문자제거         len =strlen(buf);         if(buf[len-1] == '\n')             buf[len-1] = '\0';         if(strlen(buf) == 0)             break;           retval = send(sock, buf, strlen(buf), 0);         if( retval== SOCKET_ERROR){             err_display("send()");             break;         }         printf("[TCP 클라이언트] %d 바이트를 보냈습니다.",retval);           retval = recvn(sock, buf, retval, 0);         if(retval == SOCKET_ERROR)         {             err_display("recv()");             break;         }         else if(retval == 0)             break;         buf[retval] = '\0';         printf("[TCP 클라이언트] %d바이트를 받았습니다", retval);         printf("[받은 데이터]%s\n", buf);       }     closesocket(sock);     WSACleanup();     return 0;   } //리시브 int recvn(SOCKET s, char *buf, int len, int flags) {     int received;     char *ptr = buf;     int left = len;       while(left >0){         received =recv(s,ptr,left,flags);         if(received == SOCKET_ERROR)             return SOCKET_ERROR;         else if(received == 0)             break;         left -= received;         ptr += received;     }     return (len - left); }     void err_quit(char *msg) {     LPVOID ipMsgBuf;     FormatMessage(         FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM, NULL,         WSAGetLastError(),MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),         (LPTSTR)&ipMsgBuf,0,NULL);     MessageBox(NULL, (LPCTSTR)ipMsgBuf, msg, MB_ICONERROR);     LocalFree(ipMsgBuf);     exit(-1); }   void err_display(char *msg) {     LPVOID ipMsgBuf;     FormatMessage(         FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM, NULL,         WSAGetLastError(),MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),         (LPTSTR)&ipMsgBuf,0,NULL);     printf("[%s] %s", msg, (LPCTSTR)ipMsgBuf);     LocalFree(ipMsgBuf); }*/ </winsock2.h></stdlib.h></stdio.h></stdio.h></stdlib.h></winsock2.h>