Changes between Version 7 and Version 8 of Docs/Prog/Manual/DeviceSupport/Network

Timestamp:

02/19/10 10:32:04 (15 years ago)

Author:

Don Wilson

Comment:

--

Docs/Prog/Manual/DeviceSupport/Network

@@ -343 +343 @@
 {{{
 // TCP/IP Client Example
+
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <string.h>
+
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <netdb.h>
+
+#define CHR_STX         0x02
+#define CHR_ETX         0x03
+
+#define IP_ADDR         "90.1.2.202"
+#define IP_PORT         3000
+
+#define START_CHR       CHR_STX
+#define STOP_CHR        CHR_ETX
+
+enum RcvMode { rcvIdle, rcvData };
+
+#define RCVMODE_IDLE    0
+#define RCVMODE_DATA    1
+
+/*
+ * This example connects to the server
+ * When a properly formatted message <STX>message<ETX> is received from the server
+ * it is sent back to the server
+ *
+ */
+
+int main()
+{
+        struct sockaddr_in serv_addr;
+        struct hostent *svr;
+        char buffer[50], rcv_buf[50];
+        int sockfd, n, i, rcv_pos = 0;
+        RcvMode rcvMode = rcvIdle;
+
+        sockfd = socket(AF_INET, SOCK_STREAM, 0);
+        if(sockfd < 0)
+        {
+                printf("error\r\n");
+                return -1;
+        }
+
+        svr = gethostbyname(IP_ADDR);
+        if(svr == NULL)
+        {
+                printf("error getHostbyname\r\n");
+                return -1;
+        }
+
+        memset(&serv_addr, 0, sizeof(serv_addr));
+        serv_addr.sin_family = AF_INET;
+        memcpy(&serv_addr.sin_addr.s_addr, svr->h_addr_list[0], sizeof(serv_addr.sin_addr.s_addr));
+
+        serv_addr.sin_port = htons(IP_PORT);
+        if(connect(sockfd, (struct sockaddr*)&serv_addr, sizeof(serv_addr)) < 0)
+        {
+                printf("error connecting\r\n");
+                return -1;
+        }
+
+        printf("Connected to server %s port %d waiting for message from server\r\n", IP_ADDR, IP_PORT);
+        while(1)
+        {
+                n = read(sockfd, buffer, sizeof(buffer));
+                // We are not blocking. You must copy to another buffer to be sure to get a complete message
+                // For example in one iteration of the loop you might receive:
+                //                              <STX>This is a
+                // and the nest iteration of the loop may give you:
+                //                              test message<ETX>
+                if(n > 0)
+                {
+                        for(i = 0; i < n; i++)
+                        {
+                                if(rcvMode == rcvIdle)
+                                {
+                                        if(buffer[i] == START_CHR)
+                                        {
+                                                rcvMode = rcvData;
+                                        }
+                                }
+                                else
+                                {
+                                        if(buffer[i] == STOP_CHR)
+                                        {
+                                                rcv_buf[rcv_pos] = '\0';
+                                                printf("Message received [%s]\r\n", rcv_buf);
+
+                                                // Send back the message without the <STX> and <ETX>
+                                                send(sockfd, rcv_buf, strlen(rcv_buf), 0);
+
+                                                rcv_pos = 0;
+                                                rcvMode = rcvIdle;
+                                        }
+                                        else if(rcv_pos < (int)(sizeof(rcv_buf) - 1))
+                                        {
+                                                rcv_buf[rcv_pos++] = buffer[i];
+                                        }
+                                }
+                        }
+                }
+        }
+        return 0;
+}
+
+
 }}}