I have compiled libzmq with openpgm with no changes under windows. Code here is taken from ZeroMQ Guide ("weather publisher" server/client). But if i change "tcp" to "epgm" it doesn't work any more (data is not received, but connection is established).
void test_serv()
{
// Prepare our context and publisher
void *context = zmq_ctx_new();
void *publisher = zmq_socket(context, ZMQ_PUB);
int rc = zmq_bind(publisher, "epgm://127.0.0.1:5556");
assert(rc == 0);
// Initialize random number generator
srandom((unsigned)time(NULL));
while (!stop_server)
{
// Get values that will fool the boss
int zipcode, temperature, relhumidity;
zipcode = randof(1000) + 600;
temperature = randof(215) - 80;
relhumidity = randof(50) + 10;
// Send message to all subscribers
char update[20];
sprintf(update, "%d %d %d", zipcode, temperature, relhumidity);
s_send(publisher, update);
}
LOG("END Server shutdown");
Sleep(500);
zmq_close(publisher);
zmq_ctx_destroy(context);
}
void test_sock()
{
// Socket to talk to server
LOG("Collecting updates from weather server...");
void *context = zmq_ctx_new();
void *subscriber = zmq_socket(context, ZMQ_SUB);
int rc = zmq_connect(subscriber, "epgm://127.0.0.1:5556");
assert(rc == 0);
// Subscribe to zipcode, default is NYC, 10001
char *filter = "1001 ";
rc = zmq_setsockopt(subscriber, ZMQ_SUBSCRIBE,
filter, strlen(filter));
assert(rc == 0);
// Process 100 updates
int update_nbr;
long total_temp = 0;
for (update_nbr = 0; update_nbr < 10; update_nbr++) {
char *string = s_recv(subscriber);
int zipcode, temperature, relhumidity;
sscanf(string, "%d %d %d",
&zipcode, &temperature, &relhumidity);
total_temp += temperature;
LOG(">> " << string);
free(string);
}
LOG("Average temperature for zipcode "<< filter << "was " << (int)(total_temp / update_nbr) << 'F');
zmq_close(subscriber);
zmq_ctx_destroy(context);
}
I run two functions in different threads, with tcp anything works as expected.
I have tried doing "route print 0.0.0.0" with cmd.exe and using interface IP (192.168.137.64) as prefix instead of "eth0" like shown in RFC: epgm://192.168.137.64;127.0.0.1:5556 on connect and/or bind, but this brokes my socket and raises error.
Also "PGM" requires administrator rights and i cannot test it now.
The error IS NOT "protocol not supported" errno is set to B (11) and i don't understand what does it mean (no docs on it).
EPGM is a bit finicky. According to this list post, if you're using EPGM your publisher and subscriber must be on separate hosts. More details here, it looks like this was a deliberate choice by the ZMQ team.
So, try it by spinning up your PUB and SUB on separate machines (changing the network addresses accordingly, of course).
The reason might be that windows does not support loopback capture interface. I tried weather example with protocol changed to epgm on linux and it works fine (well, shows some warnings about loopback, but the messages are transfered correctly)
Related
There are other similar questions on this site, but they either do not related to winsock2 or they are suitable only for use with ipv4 address spaces. The default compiler for Visual Studio 2019 produces an error when the ntoa function is used, hence an ipv4 and ipv6 solution is required.
I did once produce the code to do this for a Linux system however I am currently at work and do not have access to that. It may or may not be "copy and paste"-able into a windows environment with winsock2. (Edit: I will of course add that code later this evening, but of course it might not be useful.)
The following contains an example, however this is an example for client side code, not server side code.
https://www.winsocketdotnetworkprogramming.com/winsock2programming/winsock2advancedInternet3c.html
Here, the getaddrinfo() function is used to obtain a structure containing matching ipv4 and ipv6 addresses. To obtain this information there is some interaction with DNS, which is not required in this case.
I have some server code which calls accept() (after bind and listen) to accept a client connection. I want to be able to print the client ip address and port to stdout.
The most closely related question on this site is here. However the answer uses ntoa and is only ipv4 compatible.
What I have so far:
So far I have something sketched out like this:
SOCKET acceptSocket = INVALID_SOCKET;
SOCKADDR_IN addr; // both of these are NOT like standard unix sockets
// I don't know how they differ and if they can be used with standard
// unix like function calls (eg: inet_ntop)
int addrlen = sizeof addr;
acceptSocket = accept(listenSocket, (SOCKADDR*)&addr, &addrlen);
if(acceptSocket == INVALID_SOCKET)
{
// some stuff
}
else
{
const std::size_t addrbuflen = INET6_ADDRSRTLEN;
char addrbuf[addrbuflen] = '\0'
inet_ntop(AF_INET, (void*)addr.sin_addr, (PSTR)addrbuf, addrbuflen);
// above line does not compile and mixes unix style function calls
// with winsock2 structures
std::cout << addrbuf << ':' << addr.sin_port << std::endl;
}
getpeername()
int ret = getpeername(acceptSocket, addrbuf, &addrbuflen);
// addrbuf cannot convert from char[65] to sockaddr*
if(ret == ???)
{
// TODO
}
You need to access the SOCKADDR. This is effectively a discriminated union. The first field tells you whether its an IPv4 (==AF_INET) or IPv6 (==AF_INET6) address. Depending on that you cast the addr pointer to be either struct sockaddr_in* or struct sockaddr_in6*, and then read off the IP address from the relevant field.
C++ code snippet in vs2019:
char* CPortListener::get_ip_str(struct sockaddr* sa, char* s, size_t maxlen)
{
switch (sa->sa_family) {
case AF_INET:
inet_ntop(AF_INET, &(((struct sockaddr_in*)sa)->sin_addr),
s, maxlen);
break;
case AF_INET6:
inet_ntop(AF_INET6, &(((struct sockaddr_in6*)sa)->sin6_addr),
s, maxlen);
break;
default:
strncpy(s, "Unknown AF", maxlen);
return NULL;
}
return s;
}
Example:
{
...
char s[INET6_ADDRSTRLEN];
sockaddr_storage ca;
socklen_t al = sizeof(ca);
SOCKET recv = accept(sd, (sockaddr*)&ca, &al);
pObj->m_ip = get_ip_str(((sockaddr*)&ca),s,sizeof(s));
}
I have an application that is used as a control system for a presentation, under Linux and using X11. I have a USB presentation remote that acts as a very miniature keyboard (four buttons: Page Up, Page Down, and two others) which can be used to advance and go back in the presentation. I would like to have my presentation application to receive all of the events from this remote regardless of where the mouse focus is. But I would also like to be able to receive the normal mouse and keyboard events if the current window focus is on the presentation application. Using XIGrabDevice() I was able to receive all events from the remote in the presentation application regardless of the current focus but I was not able to receive any events from the mouse or keyboard while the grab was active.
I ended up setting up a separate program to capture the remote's keys, then I relay those keys to my main program. I did it this way because the original program was using the older XInput extension, and I needed to use the newer XInput2 extension, and they do not exist well together. Here's some C++ code (it doesn't do any error checking, but this should be done in a real program):
// Open connection to X Server
Display *dpy = XOpenDisplay(NULL);
// Get opcode for XInput Extension; we'll need it for processing events
int xi_opcode = -1, event, error;
XQueryExtension(dpy, "XInputExtension", &xi_opcode, &event, &error);
// Allow user to select a device
int num_devices;
XIDeviceInfo *info = XIQueryDevice(dpy, XIAllDevices, &num_devices);
for (int i = 0; i < num_devices; ++i)
{
XIDeviceInfo *dev = &info[i];
std::cout << dev->deviceid << " " << dev->name << "\n";
}
XIFreeDeviceInfo(info);
std::cout << "Enter the device number: ";
std::string input;
std::cin >> input;
int deviceid = -1;
std::istringstream istr(input);
istr >> deviceid;
// Create an InputOnly window that is just used to grab events from this device
XSetWindowAttributes attrs;
long attrmask = 0;
memset(&attrs, 0, sizeof(attrs));
attrs.override_redirect = True; // Required to grab device
attrmask |= CWOverrideRedirect;
Window win = XCreateWindow(dpy, DefaultRootWindow(dpy), 0, 0, 1, 1, 0, 0, InputOnly, CopyFromParent, attrmask, &attrs);
// Make window without decorations
PropMotifWmHints hints;
hints.flags = 2;
hints.decorations = 0;
Atom property = XInternAtom(dpy, "_MOTIF_WM_HINTS", True);
XChangeProperty(dpy, win, property, property, 32, PropModeReplace, (unsigned char *)&hints, PROP_MOTIF_WM_HINTS_ELEMENTS);
// We are interested in key presses and hierarchy changes. We also need to get key releases or else we get an infinite stream of key presses.
XIEventMask evmasks[1];
unsigned char mask0[XIMaskLen(XI_LASTEVENT)];
memset(mask0, 0, sizeof(mask0));
XISetMask(mask0, XI_KeyPress);
XISetMask(mask0, XI_KeyRelease);
XISetMask(mask0, XI_HierarchyChanged);
evmasks[0].deviceid = XIAllDevices;
evmasks[0].mask_len = sizeof(mask0);
evmasks[0].mask = mask0;
XISelectEvents(dpy, win, evmasks, 1);
XMapWindow(dpy, win);
XFlush(dpy);
XEvent ev;
bool grab_success = false, grab_changed;
while (1)
{
grab_changed = false;
if (!grab_success)
{
XIEventMask masks[1];
unsigned char mask0[XIMaskLen(XI_LASTEVENT)];
memset(mask0, 0, sizeof(mask0));
XISetMask(mask0, XI_KeyPress);
masks[0].deviceid = deviceid;
masks[0].mask_len = sizeof(mask0);
masks[0].mask = mask0;
XIGrabDevice(dpy, deviceid, win, CurrentTime, None, XIGrabModeAsync, XIGrabModeAsync, XIOwnerEvents, masks);
}
XNextEvent(dpy, &ev);
XGenericEventCookie *cookie = &ev.xcookie;
if (cookie->type == GenericEvent && cookie->extension == xi_opcode && XGetEventData(dpy, cookie))
{
if (cookie->evtype == XI_KeyPress)
{
XIDeviceEvent *de = (XIDeviceEvent*)cookie->data;
std::cout << "found XI_KeyPress event: keycode " << de->detail << "\n";
}
else if (cookie->evtype == XI_HierarchyChanged)
{
// Perhaps a device was unplugged. The client is expected to re-read the list of devices to find out what changed.
std::cout << "found XI_HierarchyChanged event.\n";
grab_changed = true;
}
XFreeEventData(dpy, cookie);
}
if (grab_changed)
{
XIUngrabDevice(dpy, deviceid, CurrentTime);
grab_success = false;
break;
}
}
I found the following links helpful:
Peter Hutterer's 6-part blog on XInput2: 1 2 3 4 5 6
This blog entry was useful to determine which class to cast the cookie->data pointer to, depending on the cookie->evtype: 7
step by step what I did so far
1) micro controller used CC3200 from Texas instruments ( wifi builted micro controller)
2) Conductive rubber cord stretch sensor - connected to Microcontroller's analog pin
**Sensor's behaviour = ( resistance increases upon stretching the conductive rubber)
So now, following is the code fo reference which I debugged in to the microcontroller to run the sensor(Using energia tool-IDE).
The code is nothing but written for the web server( which I gave- available wifi ssid and password-which you can see in the following programm "iPhone and the passowrd"), where the sensor's code is also wrote in to,
And this webserver reads and generates IP address of the microcontroller and also values of the stretch sensor.
Webserver code :
#include <SPI.h>
#include <WiFi.h>
#include <WiFiClient.h>
#include <WiFiServer.h>
// which analog pin to connect
#define RUBBERPIN A3
// how many samples to take and average, more takes longer
// but is more 'smooth'
#define NUMSAMPLES 5
// the value of the 'other' resistor
#define SERIESRESISTOR 10000
int samples[NUMSAMPLES];
// your network name also called SSID
char ssid[] = "iPhone";
// your network password
char password[] = "123456789";
// your network key Index number (needed only for WEP)
int keyIndex = 0;
WiFiServer server(3000);
void setup() {
Serial.begin(115200); // initialize serial communication
analogReference(EXTERNAL);
pinMode(RED_LED, OUTPUT); // set the LED pin mode
// attempt to connect to Wifi network:
Serial.print("Attempting to connect to Network named: ");
// print the network name (SSID);
Serial.println(ssid);
// Connect to WPA/WPA2 network. Change this line if using open or WEP
network:
WiFi.begin(ssid, password);
while ( WiFi.status() != WL_CONNECTED) {
// print dots while we wait to connect
Serial.print(".");
delay(300);
}
Serial.println("\nYou're connected to the network");
Serial.println("Waiting for an ip address");
while (WiFi.localIP() == INADDR_NONE) {
// print dots while we wait for an ip addresss
Serial.print(".");
delay(300);
}
// you're connected now, so print out the status
printWifiStatus();
Serial.println("Starting dataerver on port 3000");
server.begin(); // start the web server on port
80
Serial.println("Dataserver started!");
}
void loop() {
// listen for incoming clients
WiFiClient client = server.available();
if (client) {
Serial.println("new client");
// an http request ends with a blank line
boolean currentLineIsBlank = true;
while (client.connected()) {
uint8_t i;
float average;
// take N samples in a row, with a slight delay
for (i=0; i< NUMSAMPLES; i++) {
samples[i] = analogRead(RUBBERPIN);
delay(10);
}
// average all the samples out
average = 0;
for (i=0; i< NUMSAMPLES; i++) {
average += samples[i];
}
average /= NUMSAMPLES;
Serial.println(average);
client.println(average);
delay(10);
}
delay(1);
// close the connection:
client.stop();
Serial.println("client disonnected");
}
}
void printWifiStatus() {
// print the SSID of the network you're attached to:
Serial.print("Network Name: ");
Serial.println(WiFi.SSID());
// print your WiFi shield's IP address:
IPAddress ip = WiFi.localIP();
Serial.print("IP Address: ");
Serial.println(ip);
// print the received signal strength:
long rssi = WiFi.RSSI();
Serial.print("signal strength (RSSI):");
Serial.print(rssi);
Serial.println(" dBm");
}
After running this programm it generates IP address and sensor's values(
221.40
221.20
221.20
*********here = value missing were a noise is visible on graph
221.00
221.20
221.40
221.00
221.20
221.40
221.00
221.40
221.20
221.40
221.20
221.00
221.00
221.60
221.00
221.20
*********here = value missing were a noise is visible on graph
221.20
221.00
Now,
I wrote the generated IP address in to a client programm (In the tool- named processing.org )
Here is my client code
import processing.net.*;
Client c;
String input;
int data[];
int posx;
void setup()
{
size(1000, 500);
background(204);
stroke(0);
frameRate(5); // Slow it down a little
// Connect to the server's IP address and port
c = new Client(this, "192.168.23.2", 3000); // Replace with your server's IP
and port
posx =2;
data = new int[3];
}
void draw()
{
posx++;
// Receive data from server
if (c.available() > 0) {
input = c.readString();
input = input.substring(0, input.indexOf("\n")); // Only up to the newline
println(input);
data[0]=data[1];
data[1] = int(input); // Split values into an array
// Draw line using received coords
stroke(0);
line(posx-1, data[0]+10, posx, data[1]+10);
}
}
My results after running the following programm:
Server sending the data and client receiving the data wirelessly- its all fine
I am able to see the output signal which I am expecting. i.e., when my sensor is in rest position the output must be straight line and if I stretch my sensor the voltage signal must increase- Iam able to see all these. But,
here is a small problem
There is a noise coming out from the output signal (please have a look in to the following picture.)
Noise
So my problem is even when the sensor is in rest position- with out any stretch- there is peak coming out.
please help me
Say I have a PUB server that zmq_send()'s realtime messages to SUB client. If client is busy and can not zmq_recv() messages quick enough, then messages will be buffered in client (and/or server).
If the buffer grows too large (high water mark) then NEW messages will be dropped. For realtime messages this is the opposite of what one wants. OLD messages should be dropped to make place for NEW ones.
Is there some way to do this?
Ideally I would like the SUB client's receive queue to be either empty or contain the most recent message only. When a new message is received it would replace the old one. ( I guess the problem here would be that the client would block on zmq_recv() when the queue is empty, wasting time doing so. )
So how are realtime feeds usually implemented in ZeroMQ?
I'll answer my own question here. The setting ZMQ_CONFLATE "Keep only last message" seemed promising but it doesn't work with subscription filters. It only ever keeps one message in the queue. If you have more than one filter, both old and new messages of the other filters type gets thrown away.
Likewise the recommendation of the zeromq guide to simply to kill slow subscribers, but that doesn't seem like realistic solution. Having subscribers with different read speeds, subscribed to the same fast publisher, should be a normal use case. Some of these subscribers might live on slow computers others on fast ones, etc. ZeroMQ should be able to handle that somehow.
http://zguide.zeromq.org/page:all#Slow-Subscriber-Detection-Suicidal-Snail-Pattern
I ended up doing manual dropping of old queued up messages on the client side. It seems to work fine. I get subscribed messages to the client that are less than 3ms old (through tcp localhost) that way. This works even in cases where I have five thousand, 10 second old messages, in the queue in front of those few real-time message at the back. This is good enough for me.
I cant help but think this is something that should be provided by the library. It could probably do a better job of it.
Anyways here is the client side, old message dropping, code:
bool Empty(zmq::socket_t& socket) {
bool ret = true;
zmq::pollitem_t poll_item = { socket, 0, ZMQ_POLLIN, 0 };
zmq::poll(&poll_item, 1, 0); //0 = no wait
if (poll_item.revents & ZMQ_POLLIN) {
ret = false;
}
return ret;
}
std::vector<std::string> GetRealtimeSubscribedMessageVec(zmq::socket_t& socket_sub, int timeout_ms)
{
std::vector<std::string> ret;
struct MessageTmp {
int id_ = 0;
std::string data_;
boost::posix_time::ptime timestamp_;
};
std::map<int, MessageTmp> msg_map;
int read_msg_count = 0;
int time_in_loop = 0;
auto start_of_loop = boost::posix_time::microsec_clock::universal_time();
do {
read_msg_count++;
//msg format sent by publisher is: filter, timestamp, data
MessageTmp msg;
msg.id_ = boost::lexical_cast<int>(s_recv(socket_sub));
msg.timestamp_ = boost::posix_time::time_from_string(s_recv(socket_sub));
msg.data_ = s_recv(socket_sub);
msg_map[msg.id_] = msg;
auto now = boost::posix_time::microsec_clock::universal_time();
time_in_loop = (now - start_of_loop).total_milliseconds();
if (time_in_loop > timeout_ms) {
std::cerr << "Timeout reached. Publisher is probably sending messages quicker than we can drop them." << std::endl;
break;
}
} while ((Empty(socket_sub) == false));
if (read_msg_count > 1) {
std::cout << "num of old queued up messages dropped: " << (read_msg_count - 1) << std::endl;
}
for (const auto &pair: msg_map) {
const auto& msg_tmp = pair.second;
auto now = boost::posix_time::microsec_clock::universal_time();
auto message_age_ms = (now - msg_tmp.timestamp_).total_milliseconds();
if (message_age_ms > timeout_ms) {
std::cerr << "[SUB] Newest message too old. f:" << msg_tmp.id_ << ", age: " << message_age_ms << "ms, s:" << msg_tmp.data_.size() << std::endl;
}
else {
std::cout << "[SUB] f:" << msg_tmp.id_ << ", age: " << message_age_ms << "ms, s:" << msg_tmp.data_.size() << std::endl;
ret.push_back(msg_tmp.data_);
}
}
return ret;
}
I have made the following win32 socket program to browse web pages. I am using wingw to avoid dependency on any runtime. To get ipaddresses I ping urls such as www.google.com, www.yahoo.com through command prompt and use those ip addreses in my program. Port is ofcourse 80.
I am able to get default pages of google, yahoo etc by using "GET /\r\n". I am also able to get non-default pages, even those inside directories, such as http://yasini.com/newsite/index.aspx by using "GET /newsite/index.aspx". The output of the program is in the form of html received from webserver, saved on hard disk. This file is later opened in firefox to see how did the communication go.
I have made a test webpage, http://a.domaindlx.com/trysite/hello.asp, which I can open in firefox. Then I ping the domain, a.domaindlx.com and get this ipaddress, 66.36.238.30. I try to access the said page by using "GET /trysite/hello.asp" but get this in response, "No web site is configured at this address. No web site is configured at this address."
I know that the said response is sent by the webserver, so I was able to connect to the webserver. The problem is that the webserver is not recognizing the url I am trying to access. I have used different webpages, both htm and asp and none is accessible.
When trying to open website using ipaddress directly in browser, I get the same error, "No website is configured...".
The basic puzzle is, why are these pages accessible through a browser such as firefox, but not through my code, when my code is essentially a browser, mean open connection with webserver at port 80.
#include windows.h
#include stdio.h
WSADATA ws;
int d;
char aa[1000];
struct sockaddr_in a;
SOCKET s;
int li;
void abc(char *p)
{
FILE *fp = fopen("c:\\data.htm", "a+");
fprintf(fp, "%s\n", p);
fclose(fp);
}
_stdcall WinMain (HINSTANCE i, HINSTANCE j, char * k, int l)
{
d = WSAStartup(0x101, &ws);
sprintf(aa, "WSASTARTUP = %d", d);
abc(aa);
s = socket(AF_INET, SOCK_STREAM, 0);
sprintf(aa, "SOCKET = %d", s);
abc(aa);
a.sin_family = AF_INET;
a.sin_port = htons(80);
//a.sin_addr.s_addr = inet_addr("74.125.236.145");
a.sin_addr.s_addr = inet_addr("66.36.238.30"); //a.domaindlx.com
//a.sin_addr.s_addr = inet_addr("206.225.85.18"); //www.domaindlx.com
//a.sin_addr.s_addr = inet_addr("87.248.122.122"); //www.yahoo.com
//a.sin_addr.s_addr = inet_addr("72.167.153.9"); //www.yasini.com
d = connect(s, (struct sockaddr *) &a, sizeof(a));
strcpy(aa, "GET /trysite/hello.asp\r\n");
strcat(aa, "HTTP 1.0 \r\n\r\n");
send(s, aa, sizeof(aa), 0);
li = 1;
while(li != 0)
{
li = recv(s, aa, 1000, 0);
abc(aa);
}
}
Note: Please enclose the header file names in the include line in angle brackets for the code to work. I had to remove that to property format the html.
The troublesome URL is running on a subdomain. The successful URLs are not. Many webservers host multiple accounts on the same physical IP(s), so they need to know which particular domain/subdomain is being requested in order to access the correct account. You need to include a Host header in your request.
Also note that when you call send() to send the request, you are sending the entire 1000 bytes of the aa buffer, which is wrong. You need to send only what you actualy filled in.
Lastly, you are not really managing the socket very well in general. You need better error handling.
Try this:
#include <windows.h>
#include <stdio.h>
void abc(char *p, int l = -1)
{
FILE *fp = fopen("c:\\data.htm", "a+");
if (fp)
{
if (l == -1) l = strlen(p);
fwrite(p, 1, l, fp);
fclose(fp);
}
}
int WINAPI WinMain (HINSTANCE i, HINSTANCE j, char * k, int l)
{
char aa[1000];
WSADATA ws;
int d = WSAStartup(0x101, &ws);
sprintf(aa, "WSASTARTUP = %d\n", d);
abc(aa);
if (d == 0)
{
SOCKET s = socket(AF_INET, SOCK_STREAM, 0);
sprintf(aa, "SOCKET = %d\n", s);
abc(aa);
if (s != INVALID_SOCKET)
{
char *host = "a.domaindlx.com";
char *file = "/trysite/hello.asp";
struct sockaddr_in a;
memset(&a, 0, sizeof(a));
a.sin_family = AF_INET;
a.sin_port = htons(80);
struct hostent *h = gethostbyname(host);
if (!h)
{
sprintf(aa, "gethostbyname(\"%s\") FAILED\n", host);
abc(aa);
}
else
{
sprintf(aa, "gethostbyname(\"%s\") TYPE = %d\n", host, h->h_addrtype);
abc(aa);
if (h->h_addrtype == AF_INET)
{
a.sin_addr = * (struct in_addr*) h->h_addr;
sprintf(aa, "gethostbyname(\"%s\") IP = %s\n", host, inet_ntoa(a.sin_addr));
abc(aa);
d = connect(s, (struct sockaddr *) &a, sizeof(a));
sprintf(aa, "CONNECT = %d\n", d);
abc(aa);
if (d == 0)
{
sprintf(aa,
"GET %s HTTP/1.0\r\n"
"Host: %s\r\n"
"Connection: close\r\n"
"\r\n",
file, host);
char *p = aa;
int t = strlen(aa);
int li;
do
{
li = send(s, p, t, 0);
if (li < 1)
break;
p += li;
t -= li;
}
while (t > 0);
if (t != 0)
{
abc("SEND FAILED\n");
}
else
{
abc("SEND OK\n");
do
{
li = recv(s, aa, sizeof(aa), 0);
if (li < 1)
break;
abc(aa, li);
}
while (true);
}
}
}
}
closesocket(s);
}
WSACleanup();
}
return 0;
}
I strongly suggest you get a packet sniffer, such as Wireshark. Then you can see EXACTLY what webbrowsers (or any other socket app) is actually sending and receiving. Then you can match that in your code as needed.
There are two problems with your code. The first one is that there should be a space not \r\n before HTTP 1.0. Without this your are sending HTTP 0.9.
The second problem is that some IP addresses are used to host multiple sites and require sending a Host header.
The site that tells you "No web site is configured at this address" may work better if you add the Host: header. Your request to that site should look like this:
"GET /trysite/hello.asp HTTP 1.0\r\nHost: a.domaindlx.com\r\n\r\n"
You're not following the protocol correctly. You want GET /trysite/hello.asp HTTP/1.0\r\n\r\n See here for the full spec.