Description of this paper

write C program




HERE IS A CODE: (HUNT);#include;#include;#include;#ifdef WIN;#include;#include;#endif;#ifndef WIN;#include;#include;#include;#endif;#define PORT 20009;/* simple upd server;this program receives short messages (<99 characters) from any IP address;and writes them to the display;be sure to use the linker line option "-l wsock32";*/;int main();/* first define a socket;a socket is an I/O port like a file descriptor;*/;#ifdef WIN;SOCKET sock, /* SOCKET is a typedef for a structure */;#else;int sock;#endif;int size;int nbytes, flags;#ifdef WIN;int addrlen;#else;socklen_t addrlen;#endif;int i;/* char loopback[20]="", */;#ifdef WIN;WSADATA wsaData, /* This is struct holds Windows required data */;int nCode;#endif;char buffer[100];struct sockaddr_in server, /* this holds my IP address and port info */;struct sockaddr_in from, /* this holds the same info for the sender of the packet;I received */;/* the call to WSAStartup is Windows magic */;#ifdef WIN;if((nCode = WSAStartup(MAKEWORD(1,1), &wsaData)) != 0);printf("Opps! WSA error %d\n",nCode);exit;#endif;/* create a socket called sock. It is a datagram socket */;sock = socket(AF_INET,SOCK_DGRAM,0);if(sock < 0);printf("socket error = %d\n", sock);return -1;server.sin_family = AF_INET, /* initialize the server address family */;server.sin_addr.s_addr = htonl(INADDR_ANY), /* notice this struct within a struct */;/* printf("%x\n",server.sin_addr.s_addr), */;server.sin_port = htons(PORT);/* associate the socket with the address structure - this is called binding */;i = bind(sock, (struct sockaddr *) &server, sizeof(server));if(i 0) && (size < 99));buffer[size] = '\0', /* add the null byte so buffer now holds a string */;i = puts((char *) buffer), /* write this string to the display */;#ifdef WIN;system("PAUSE");#endif;return 0;HERE IS ANOTHER ONE;#include;#include;#include;#ifdef WIN;#include;#include;#endif;#ifndef WIN;#include;#include;#include;#endif;/* Here are some details of the sockaddr_in structure and the sockaddr structure;These declarations are copied from winsock.h;struct in_addr { this struct holds a 32 bit IP address;union;struct { u_char s_b1,s_b2,s_b3,s_b4, } S_un_b;struct { u_short s_w1,s_w2, } S_un_w;u_long S_addr;S_un;#define s_addr S_un.S_addr;struct sockaddr_in { notice this structure is 16 bytes long;short sin_family;u_short sin_port;struct in_addr sin_addr;char sin_zero[8];struct sockaddr { this generic address structure is 16 bytes long, too!;u_short sa_family;char sa_data[14];*/;/* we have to send on the same port the server is listening on */;#define PORT 20009;/* simple upd client */;int main();#ifdef WIN;SOCKET sock;#else;int sock;#endif;int size;int nbytes, flags;int i;char * cp;#ifdef WIN;WSADATA wsaData;int nCode;#endif;char buffer[100];char str_addr[20], /* holds the chars of an IP address */;struct sockaddr_in target_pc, me;/* magic call to initialize the network I/O code - only Microsoft requires this */;#ifdef WIN;if((nCode = WSAStartup(MAKEWORD(1,1), &wsaData)) != 0);printf("Opps! WSA error %d\n",nCode);return -1;#endif;/* create a socket to send on */;sock = socket(PF_INET,SOCK_DGRAM,0);if(sock < 0);printf("socket error = %d\n", sock);return -1;/* we fill in the address family and port, but we do not know the destination IP address yet */;target_pc.sin_family = PF_INET;target_pc.sin_port = htons(PORT);/* fill in my address and port */;me.sin_family = PF_INET;me.sin_port = htons(0);me.sin_addr.s_addr = htonl(INADDR_ANY);i = bind(sock, (struct sockaddr *) &&me, sizeof(me));if(i < 0);printf("bind result: %d\n", i);return -1;nbytes = 99;while(1);printf("Enter the target IP address: ");cp = fgets(str_addr,19,stdin);/* remove the \n */;str_addr[strlen(str_addr)-1] = '\0';/* the inet_addr function converts a string form of IP address to a 32 binary integer */;target_pc.sin_addr.s_addr = inet_addr(&&str_addr[0]);printf("Enter your message: ");cp = fgets(buffer,99,stdin);/* get the string length so we send exactly this many characters */;nbytes = strlen(buffer);flags = 0;size = sendto(sock, (char *) buffer, nbytes,flags,(struct sockaddr *)&target_pc,sizeof(target_pc));printf("msg size = %d size = %d\n", nbytes, size);#ifdef WIN;system("PAUSE");#endif;return 0


Paper#64020 | Written in 18-Jul-2015

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