Some auxiliary functions of linux_c socket datagram

1 /********************************************************************2 * DGRAM.C3 * Support functions for datagram based programs4  */5#include <stdio.h>6#include <unistd.h>7#include <sys/types.h>8#include <sys/socket.h>9#include <netinet/inch.h>Ten#include <arpa/inet.h> One#include <netdb.h> A#include <string.h> -  - #defineHostlen 256 the  - intmake_internet_address (); - /********************************************************************* - * for UDP (datagram server side) it is not as complex as TCP.  + * Server-side Application layer main call: - * Fd=socket (); + * BIND (FD, server address port), bind FD Source address, Destination address arbitrary A * (loop multiple times below) at * Recvfrom (FD, buf, size, addr) blocks waiting for client data requests and can learn from addr who sent the request - * Recvfrom Returns processing client requests - * SendTo (CONNFD, buf, size, addr) Send data reply to client address port addr -  ********************************************************************/ - intMake_dgram_server_soket (intportnum) { -   structSockaddr_in saddr;/*build our address here*/ in   CharHostname[hostlen];/*Address*/ -   intsock_id;/*The socket*/ to    +Sock_id=socket (Pf_inet, Sock_dgram,0);/*get a socket*/ -   if(sock_id = =-1)return-1; the  *   /** Build address and bind it to socket**/ $   Panax Notoginseng gethostname (hostname, hostlen); -Make_internet_address (hostname, Portnum, &saddr); the    +   if(Bind (sock_id, (structsockaddr*) &saddr,sizeof(SADDR))! =0) A     return-1; the    +   returnsock_id; - } $ /********************************************************************* $ * Not as complex as TCP for UDP (datagram client) - * The client application layer primarily calls: - * Fd=socket () assigns a file descriptor the * (loop multiple times below) - * SendTo (FD, buf, size, addr) sends a data request to the server address port addrWuyi * Recvfrom (FD, buf, size, addr) blocking wait for reply the * Recvfrom return - * End of cycle Wu * Close (FD) closed file descriptor -  ********************************************************************/ About intMake_dgram_client_socket () { $   returnSockets (Pf_inet, SOCK_DGRAM,0); - } -  - intMake_internet_address (Char* hostname,intPortstructSOCKADDR_IN *ADDRP) { A /* + * constructor for an Internet socket address, uses hostname and port the * (host, Port), *ADDRP; -  */ $   structHostent *HP; the    theBzero ((void*) ADDRP,sizeof(structsockaddr_in)); thehp=gethostbyname (hostname); the   if(Hp==null)return-1; -Bcopy ((void*) Hp->h_addr, (void*) &addrp->sin_addr, hp->h_length); inaddrp->sin_port=htons (port); theaddrp->sin_family=af_inet; the   return 0; About } the  the intGet_internet_address (Char* Host,intLenint*PORTP,structSOCKADDR_IN *ADDRP) { the /* + * Extracts host and port from an Internet socket address - * *addrp-> (host, Port) the  */Bayistrncpy (Host, Inet_ntoa (addrp->sin_addr), Len); the*portp=nthos (addrp->sin_port); the   return 0; -}

Some auxiliary functions of linux_c socket datagram