dist intro client/server code

dist-intro/udp.c

@@ -0,0 +1,67 @@
+#include "udp.h"
+
+// create a socket and bind it to a port on the current machine
+// used to listen for incoming packets
+int UDP_Open(int port) {
+    int fd;           
+    if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) == -1) {
+	perror("socket");
+	return 0;
+    }
+
+    // set up the bind
+    struct sockaddr_in my_addr;
+    bzero(&my_addr, sizeof(my_addr));
+
+    my_addr.sin_family      = AF_INET;
+    my_addr.sin_port        = htons(port);
+    my_addr.sin_addr.s_addr = INADDR_ANY;
+
+    if (bind(fd, (struct sockaddr *) &my_addr, sizeof(my_addr)) == -1) {
+	perror("bind");
+	close(fd);
+	return -1;
+    }
+
+    return fd;
+}
+
+// fill sockaddr_in struct with proper goodies
+int UDP_FillSockAddr(struct sockaddr_in *addr, char *hostname, int port) {
+    bzero(addr, sizeof(struct sockaddr_in));
+    if (hostname == NULL) {
+	return 0; // it's OK just to clear the address
+    }
+    
+    addr->sin_family = AF_INET;          // host byte order
+    addr->sin_port   = htons(port);      // short, network byte order
+
+    struct in_addr *in_addr;
+    struct hostent *host_entry;
+    if ((host_entry = gethostbyname(hostname)) == NULL) {
+	perror("gethostbyname");
+	return -1;
+    }
+    in_addr = (struct in_addr *) host_entry->h_addr;
+    addr->sin_addr = *in_addr;
+
+    return 0;
+}
+
+int UDP_Write(int fd, struct sockaddr_in *addr, char *buffer, int n) {
+    int addr_len = sizeof(struct sockaddr_in);
+    int rc = sendto(fd, buffer, n, 0, (struct sockaddr *) addr, addr_len);
+    return rc;
+}
+
+int UDP_Read(int fd, struct sockaddr_in *addr, char *buffer, int n) {
+    int len = sizeof(struct sockaddr_in); 
+    int rc = recvfrom(fd, buffer, n, 0, (struct sockaddr *) addr, (socklen_t *) &len);
+    // assert(len == sizeof(struct sockaddr_in)); 
+    return rc;
+}
+
+int UDP_Close(int fd) {
+    return close(fd);
+}
+