added UDP examples

socket_examples/simple_client.c → socket_examples/simple_tcp_client.c

@@ -54,7 +54,7 @@ int main(int argc, char *argv[])
         port = SERVER_PORT;
     }
 
-    printf("simple_client: connecting to server: %s, port %d\n",server_name, port);
+    printf("simple_tcp_client: connecting to server: %s, port %d\n",server_name, port);
 
     init(server_name, port);
     make_request();
@@ -67,7 +67,7 @@ static void make_request()
 {
     char msg[BUFSZ];
 #ifdef DEBUG
-    printf("simple_client: connecting\n");
+    printf("simple_tcp_client: connecting\n");
 #endif
     socket_init();
     if (connect(sockfd, (struct sockaddr*)&serv_addr, sizeof(serv_addr)) < 0) {
@@ -78,7 +78,7 @@ static void make_request()
             perror("ERROR reading from motion server");
         } else {
             msg[res]='\0'; /* ensure msg is null terminated */
-            printf("simple_client: response: %s\n",msg);
+            printf("simple_tcp_client: response: %s\n",msg);
         }
         socket_close();
     }

socket_examples/simple_server.c → socket_examples/simple_tcp_server.c

@@ -48,7 +48,7 @@ static int bind_server_socket(int fd, int port){
     if(bind(fd, (struct sockaddr*) &addr, sizeof(addr))) return -1;
 
 #ifdef INFO
-    printf("simple_server: bound fd %d to port %d\n",fd,port);
+    printf("simple_tcp_server: bound fd %d to port %d\n",fd,port);
 #endif
     
     return fd;
@@ -65,10 +65,10 @@ static int do_serve(int fd)
                       "BYE.\n";
     size_t len = strlen(msg);
     
-    printf("simple_server: attempting accept on fd %d\n",fd);
+    printf("simple_tcp_server: attempting accept on fd %d\n",fd);
     if((clientfd = accept(fd, NULL, NULL)) < 0) return -1;
 #ifdef INFO
-    printf("simple_server: writing msg (len=%lu) to clientfd (%d)\n",len,clientfd);
+    printf("simple_tcp_server: writing msg (len=%lu) to clientfd (%d)\n",len,clientfd);
 #endif
     
 #ifdef WRITE_LOOP
@@ -80,7 +80,7 @@ static int do_serve(int fd)
             goto error;
         }
 #ifdef INFO
-        printf("simple_server: write returned %d\n",res);
+        printf("simple_tcp_server: write returned %d\n",res);
 #endif
         written += res;
     } while (written < len);
@@ -95,7 +95,7 @@ static int do_serve(int fd)
 #endif
 
  error:
-    printf("simple_server: closing clientfd (%d)\n",clientfd);
+    printf("simple_tcp_server: closing clientfd (%d)\n",clientfd);
     return close(clientfd);
 }
 
@@ -110,7 +110,7 @@ int main()
 
     do_serve(fd);
 
-    printf("simple_server: closing socket: %d\n", fd);
+    printf("simple_tcp_server: closing socket: %d\n", fd);
     close(fd);
 
     return 0;

socket_examples/simple_udp_client.c

+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+#include <sys/socket.h>
+#include <netinet/ip.h>
+#include <arpa/inet.h>
+#include <netdb.h>
+
+#include <string.h>
+
+#define BUFSZ 1024
+#define SERVER_PORT 5000
+
+/*
+ * create a datagram socket 
+ */
+int create_socket()
+{
+    int fd = -1;
+    
+    fd = socket(AF_INET,SOCK_DGRAM,IPPROTO_UDP);
+    return fd;
+}
+
+#undef USE_IP_NUMBER 
+static int init_remote(struct sockaddr_in* remote_end, socklen_t remote_size, const char* server_str, int port )
+{
+    memset((char*) &remote_end, 0, remote_size);
+    remote_end->sin_family = AF_INET;
+    remote_end->sin_port = htons(port);
+#ifdef USE_IP_NUMBER
+    if (inet_aton(server_str , &remote_end->sin_addr) == 0) 
+    {
+        fprintf(stderr, "inet_aton() failed\n");
+        return -1;
+    }
+#else
+    {
+        struct hostent* server;
+        server = gethostbyname(server_str);
+        if (server == NULL) {
+            fprintf(stderr,"ERROR, server name not found\n");
+            return -1;
+        } else {
+            bcopy((char *)server->h_addr, (char *)&remote_end->sin_addr.s_addr, server->h_length);
+        }
+    }
+
+#endif
+
+    
+}
+
+/*
+ * Send a datagram to server and wait for one reply 
+ */
+static int send_and_receive(int fd, const char* server_str, int port)
+{
+    char buf[BUFSZ];
+    struct sockaddr_in remote_end;
+    socklen_t remote_size = sizeof(remote_end);
+
+    if(port < 0 || port > 65535) {
+       errno = EINVAL;
+       return -1;
+    }
+
+    printf("simple_udp_client: sending to %s:%d (fd=%d)\n",server_str,port,fd);
+
+    init_remote(&remote_end, remote_size, server_str, port);
+
+    
+    const char* msg = "Hello, socket!\n"
+                     "I am a text\n"
+                      "BYE.\n";
+    ssize_t len = strlen(msg);
+    len = sendto(fd, msg, len, 0, (struct sockaddr*) &remote_end, remote_size);
+    if(len == -1){
+        perror("sendto");
+        return len;
+    }
+    printf("simple_udp_client: waiting for datagram on fd %d\n",fd);
+    
+    len = recvfrom(fd, buf, BUFSZ-1, 0, (struct sockaddr*) &remote_end, &remote_size);
+    if(len == -1){
+        perror("recvfrom");
+        return len;
+    }
+    buf[len] = 0; /* add null termination to string*/
+    
+
+    printf("simple_udp_client: received packet from %s:%d, len=%zu\n%s\n",
+           inet_ntoa(remote_end.sin_addr),
+           ntohs(remote_end.sin_port),
+           len,
+           buf);
+    
+    return 0;
+}
+
+int main(int argc, char *argv[])
+{
+    const char* server_str;
+    int port;
+    int fd;
+
+    if(argc>=2) {
+        server_str = argv[1];
+    } else {
+#ifdef USE_IP_NUMBER
+        server_str = "127.0.0.1";
+#else
+        server_str = "localhost";
+#endif
+    }
+    if(argc==3) {
+        port = atoi(argv[2]);
+    } else {
+        port = SERVER_PORT;
+    }
+
+    // printf("simple_client: connecting to server: %s, port %d\n",server_str, port);
+    fd = create_socket();
+
+    if(fd < 0){
+        perror("create_socket");
+        return 1;
+    }
+
+
+    printf("calling send_and_receive for %s,%d\n",server_str,port);
+    send_and_receive(fd, server_str, port);
+
+    printf("simple_udp_client: closing socket: %d\n", fd);
+    close(fd);
+
+    return 0;
+}
+

socket_examples/simple_udp_server.c

+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+#include <sys/socket.h>
+#include <netinet/ip.h>
+#include <arpa/inet.h>
+#include <string.h>
+
+#define BUFSZ 1024
+#define SERVER_PORT 5000
+
+static int bind_socket(int fd, int port);
+
+/*
+ * create a server socket bound to port
+ * and listening.
+ *  
+ * return positive file descriptor 
+ * or negative value on error
+ */
+int create_socket(int port)
+{
+    int fd = -1;
+    
+    if(port < 0 || port > 65535) {
+       errno = EINVAL;
+       return -1;
+    }
+    fd = socket(AF_INET,SOCK_DGRAM,IPPROTO_UDP);
+    if(fd < 0) return fd;
+    if(bind_socket(fd,port) < 0) return -1;
+    printf("simple_udp_server: bound socket to port %d\n",port);
+    return fd;
+}
+
+static int bind_socket(int fd, int port){
+
+    struct sockaddr_in addr;
+    // if(setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &val, sizeof(val))) {
+    //     perror("setsockopt");
+    //     return -1;
+    // }
+    
+    /* see man page ip(7) */
+    addr.sin_family = AF_INET;
+    addr.sin_port = htons(port);
+    addr.sin_addr.s_addr = htonl(INADDR_ANY);
+
+    if(bind(fd, (struct sockaddr*) &addr, sizeof(addr))) return -1;
+
+#ifdef INFO
+    printf("simple_server: bound fd %d to port %d\n",fd,port);
+#endif
+    
+    return fd;
+}
+
+/*
+ * Wait for one datagram and echo it back
+ */
+static int do_serve(int fd)
+{
+    char buf[BUFSZ];
+    struct sockaddr_in remote_end;
+    socklen_t remote_size = sizeof(remote_end);
+    
+   //  const char* msg = "Hello, socket!\n"
+   //                    "I am a text\n"
+   //                    "BYE.\n";
+   // size_t len = strlen(msg);
+   ssize_t len;
+    
+    printf("simple_server: waiting for datagram on fd %d\n",fd);
+    
+    len = recvfrom(fd, buf, BUFSZ-1, 0, (struct sockaddr*) &remote_end, &remote_size);
+    if(len == -1){
+        perror("recvfrom");
+        return len;
+    }
+    buf[len] = 0; /* add null termination to string*/
+    
+
+    printf("simple_server: received packet from %s:%d, len=%zu\n%s\n",
+           inet_ntoa(remote_end.sin_addr),
+           ntohs(remote_end.sin_port),
+           len,
+           buf);
+    
+    len = sendto(fd, buf, len, 0, (struct sockaddr*) &remote_end, remote_size);
+    if(len == -1){
+        perror("sendto");
+        return len;
+    }
+    return 0;
+}
+
+int main(int argc, char *argv[])
+{
+    const char* server_name;
+    int port;
+    int fd;
+
+    if(argc>=2) {
+        server_name = argv[2];
+    } else {
+        server_name = "localhost";
+    }
+    if(argc==3) {
+        port = atoi(argv[3]);
+    } else {
+        port = SERVER_PORT;
+    }
+
+    // printf("simple_client: connecting to server: %s, port %d\n",server_name, port);
+    fd = create_socket(port);
+
+    if(fd < 0){
+        perror("create_socket");
+        return 1;
+    }
+
+    do_serve(fd);
+
+    printf("simple_server: closing socket: %d\n", fd);
+    close(fd);
+
+    return 0;
+}
+