Updated UDP implementation

1 files changed, 94 insertions, 0 deletions

diff --git a/test/echo/echo.c b/test/echo/echo.c
new file mode 100644
index 0000000..693a07d
--- /dev/null
+++ b/test/echo/echo.c
@@ -0,0 +1,94 @@
+/* UDP echo server program -- echo-server-udp.c */
+
+#include <stdio.h>      /* standard C i/o facilities */
+#include <stdlib.h>     /* needed for atoi() */
+#include <unistd.h>     /* defines STDIN_FILENO, system calls,etc */
+#include <sys/types.h>  /* system data type definitions */
+#include <sys/socket.h> /* socket specific definitions */
+#include <netinet/in.h> /* INET constants and stuff */
+#include <arpa/inet.h>  /* IP address conversion stuff */
+#include <netdb.h>      /* gethostbyname */
+
+
+
+/* this routine echos any messages (UDP datagrams) received */
+
+#define MAXBUF 1024*1024
+
+void echo( int sd ) {
+    int len,n;
+    char bufin[MAXBUF];
+    struct sockaddr_in remote;
+
+    /* need to know how big address struct is, len must be set before the
+       call to recvfrom!!! */
+
+    len = sizeof(remote);
+
+    while (1) {
+      /* read a datagram from the socket (put result in bufin) */
+      n=recvfrom(sd,bufin,MAXBUF,0,(struct sockaddr *)&remote,&len);
+
+      /* print out the address of the sender */
+      printf("Got a datagram from %s port %d\n",
+             inet_ntoa(remote.sin_addr), ntohs(remote.sin_port));
+
+      if (n<0) {
+        perror("Error receiving data");
+      } else {
+        printf("GOT %d BYTES\n",n);
+        /* Got something, just send it back */
+        sendto(sd,bufin,n,0,(struct sockaddr *)&remote,len);
+      }
+    }
+}
+
+/* server main routine */
+
+int main() {
+  int ld;
+  struct sockaddr_in skaddr;
+  int length;
+
+  /* create a socket
+     IP protocol family (PF_INET)
+     UDP protocol (SOCK_DGRAM)
+  */
+
+  if ((ld = socket( PF_INET, SOCK_DGRAM, 0 )) < 0) {
+    printf("Problem creating socket\n");
+    exit(1);
+  }
+
+  /* establish our address
+     address family is AF_INET
+     our IP address is INADDR_ANY (any of our IP addresses)
+     the port number is assigned by the kernel
+  */
+
+  skaddr.sin_family = AF_INET;
+  skaddr.sin_addr.s_addr = htonl(INADDR_ANY);
+  skaddr.sin_port = htons(0);
+
+  if (bind(ld, (struct sockaddr *) &skaddr, sizeof(skaddr))<0) {
+    printf("Problem binding\n");
+    exit(0);
+  }
+
+  /* find out what port we were assigned and print it out */
+
+  length = sizeof( skaddr );
+  if (getsockname(ld, (struct sockaddr *) &skaddr, &length)<0) {
+    printf("Error getsockname\n");
+    exit(1);
+  }
+
+  /* port number's are network byte order, we have to convert to
+     host byte order before printing !
+  */
+  printf("The server UDP port number is %d\n",ntohs(skaddr.sin_port));
+
+  /* Go echo every datagram we get */
+  echo(ld);
+  return(0);
+}