added simple client example

socket_examples/simple_client.c

+/*
+A minimal example of a TCP client
+ */
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <signal.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <netdb.h>
+
+#ifndef SERVER_PORT
+#define SERVER_PORT 5000
+#endif
+
+void init(const char* server_name, int port);
+static void socket_init();
+static void socket_close();
+static void make_request();
+
+
+int sockfd=-1;
+struct hostent *server;
+struct sockaddr_in serv_addr;
+
+void init(const char* server_name, int port)
+{
+    server = gethostbyname(server_name);
+    if (server == NULL) {
+        fprintf(stderr,"ERROR, server name not found\n");
+        exit(1);
+    } else {
+        bzero((char *) &serv_addr, sizeof(serv_addr));
+        serv_addr.sin_family = AF_INET;
+        bcopy((char *)server->h_addr, (char *)&serv_addr.sin_addr.s_addr, server->h_length);
+        serv_addr.sin_port = htons(port);
+    }
+}
+
+int main(int argc, char *argv[])
+{
+    const char* server_name;
+    int port;
+
+    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);
+
+    init(server_name, port);
+    make_request();
+
+    return 0;
+}
+
+#define BUFSZ 100
+static void make_request()
+{
+    char msg[BUFSZ];
+#ifdef DEBUG
+    printf("simple_client: connecting\n");
+#endif
+    socket_init();
+    if (connect(sockfd, (struct sockaddr*)&serv_addr, sizeof(serv_addr)) < 0) {
+        perror("ERROR connecting");
+    } else {
+        int res = read(sockfd, msg, BUFSZ-1);
+        if(res < 0) {
+            perror("ERROR reading from motion server");
+        } else {
+            msg[res]='\0'; /* ensure msg is null terminated */
+            printf("simple_client: response: %s\n",msg);
+        }
+        socket_close();
+    }
+}
+
+static void socket_init()
+{
+    sockfd = socket(AF_INET, SOCK_STREAM, 0);
+    if (sockfd < 0) {
+        perror("creating motion socket");
+    }
+}
+static void socket_close()
+{
+    if (sockfd) {
+        if(close(sockfd)){
+            perror("closing motion socket");
+        }
+    }
+    sockfd=-1;
+}