68 lines
1.8 KiB
C
68 lines
1.8 KiB
C
#include "udp.h"
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// create a socket and bind it to a port on the current machine
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// used to listen for incoming packets
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int UDP_Open(int port) {
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int fd;
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if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) == -1) {
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perror("socket");
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return 0;
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}
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// set up the bind
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struct sockaddr_in my_addr;
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bzero(&my_addr, sizeof(my_addr));
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my_addr.sin_family = AF_INET;
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my_addr.sin_port = htons(port);
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my_addr.sin_addr.s_addr = INADDR_ANY;
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if (bind(fd, (struct sockaddr *) &my_addr, sizeof(my_addr)) == -1) {
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perror("bind");
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close(fd);
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return -1;
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}
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return fd;
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}
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// fill sockaddr_in struct with proper goodies
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int UDP_FillSockAddr(struct sockaddr_in *addr, char *hostname, int port) {
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bzero(addr, sizeof(struct sockaddr_in));
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if (hostname == NULL) {
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return 0; // it's OK just to clear the address
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}
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addr->sin_family = AF_INET; // host byte order
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addr->sin_port = htons(port); // short, network byte order
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struct in_addr *in_addr;
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struct hostent *host_entry;
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if ((host_entry = gethostbyname(hostname)) == NULL) {
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perror("gethostbyname");
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return -1;
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}
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in_addr = (struct in_addr *) host_entry->h_addr;
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addr->sin_addr = *in_addr;
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return 0;
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}
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int UDP_Write(int fd, struct sockaddr_in *addr, char *buffer, int n) {
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int addr_len = sizeof(struct sockaddr_in);
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int rc = sendto(fd, buffer, n, 0, (struct sockaddr *) addr, addr_len);
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return rc;
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}
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int UDP_Read(int fd, struct sockaddr_in *addr, char *buffer, int n) {
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int len = sizeof(struct sockaddr_in);
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int rc = recvfrom(fd, buffer, n, 0, (struct sockaddr *) addr, (socklen_t *) &len);
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// assert(len == sizeof(struct sockaddr_in));
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return rc;
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}
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int UDP_Close(int fd) {
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return close(fd);
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}
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