Tell me please. There is an Xprinter q260 receipt printer. How can I send esc / pos commands to it using the web?
The printer is connected to ethernet.
When switching to http://192.168.0.110:9100, the printer prints information about the device from which they clicked on a web link.
Suppose you use C++, then for this, I made a class. Here some snippets of the class to re-use:
to open a socket for the printer:
m_sock =socket( AF_INET, SOCK_STREAM, 0);
int on =1;
if ( setsockopt( m_sock, SOL_SOCKET, SO_REUSEADDR, (const char*) &on,
sizeof(on)) == -1)
return false;
to connect to the printer:
sockaddr_in m_addr;
m_addr.sin_family =AF_INET;
m_addr.sin_port =htons( port);
int status =inet_pton( AF_INET, host.c_str(), &m_addr.sin_addr);
if ( errno == EAFNOSUPPORT)
return false;
status =::connect( m_sock, (sockaddr *) &m_addr, sizeof(m_addr));
return ( status == 0) ? true:false;
to print data to the printer:
int bytes_sent = ::send( m_sock, data, length, MSG_NOSIGNAL );
to close the printer after the job:
::close( m_sock);
Related
I'm currently using a Esp32 which presents, in addition to wifi, an ethernet interface.
I'm using the esp-idf v3.3 with FreeRTOS.
To use it I included the "esp_eth.h" library (https://docs.espressif.com/projects/esp-idf/en/release-v3.1/api-reference/ethernet/esp_eth.html#api-reference-phy-lan8720).
I'd like to use both Wifi and ethernet interfaces basing on what I want to do but selecting which one to use, is there a way?
The practical use is to receive a command through the ethernet interface (for example a site to ping), ping the server through the wifi interface and answer back to the ethernet interface the ping result.
How can I select which interface to use (i dont want that the ping is made through the ethernet or that the response go through the wifi).
#edit: i found the method netif_set_default(struct netif * netif), but i dont know if it is the best way to select the interface to use for the specific action(i should swap from one interface to another)
Just get the IP of the Ethernet interface, then bind a socket to that IP address.
struct in_addr iaddr = {0};
#if USE_ANY_IF
// Bind the socket to any address
iaddr.s_addr = htonl(INADDR_ANY);
#else
// bind only to the Ethernet interface
tcpip_adapter_ip_info_t ip_info = {0};
tcpip_adapter_get_ip_info(TCPIP_ADAPTER_IF_ETH, &ip_info);
inet_addr_from_ip4addr(&iaddr, &ip_info.ip);
#endif
Then use it to bind a socket, for example:
static int create_multicast_ipv4_socket(struct in_addr bind_iaddr)
{
struct sockaddr_in saddr = {0};
int sock = -1;
int err = 0;
char addrbuf[32] = {0};
sock = socket(PF_INET, SOCK_DGRAM, IPPROTO_IP);
if (sock < 0)
{
ESP_LOGE(V4TAG, "Failed to create socket. Error %d", errno);
return -1;
}
saddr.sin_addr.s_addr = bind_iaddr.s_addr; // what interface IP to bind to. Can be htonl(INADDR_ANY)
saddr.sin_family = PF_INET;
saddr.sin_port = htons(UDP_PORT);
inet_ntoa_r(saddr.sin_addr.s_addr, addrbuf, sizeof(addrbuf) - 1);
ESP_LOGI(TAG, "Binding to interface %s...", addrbuf);
err = bind(sock, (struct sockaddr *)&saddr, sizeof(struct sockaddr_in));
if (err < 0)
{
ESP_LOGE(V4TAG, "Failed to bind socket. Error %d", errno);
goto err;
}
// Assign multicast TTL (set separately from normal interface TTL)
uint8_t ttl = MULTICAST_TTL;
setsockopt(sock, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(uint8_t));
if (err < 0)
{
ESP_LOGE(V4TAG, "Failed to set IP_MULTICAST_TTL. Error %d", errno);
goto err;
}
// All set, socket is configured for sending
return sock;
err:
close(sock);
return -1;
}
I'm trying to send some up sensor data from arduino to my iPhone and i found here (http://www.benripley.com/development/ios/udp-server-on-iphone/) and I run it with some small mods to make it compile on a viewController I display the data and everything works perfectly. But when I leave the view and go back, probably because it tries to start the server again, the app crashes. i tried to move the code to the appDelegate to start the server on launch but the app crashes on launch. even if I try only to start the server on launch and start reading by the time I enter the view and the same thing happens. Any idea?
here is the code:
#include < sys/socket.h >
#include < arpa/inet.h >
#include < errno.h >
#define UDP 17
typedef struct sockaddr_in sockaddr_in;
- (void)startServer {
NSLog(#"UDP Server started...");
sock = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP);
struct sockaddr_in sa;
memset(&sa, 0, sizeof(sa));
sa.sin_family = AF_INET;
sa.sin_addr.s_addr = INADDR_ANY;
sa.sin_port = htons(5009);
// bind the socket to our address
if (-1 == bind(sock,(struct sockaddr *)&sa, sizeof(struct sockaddr)))
{
perror("error bind failed");
close(sock);
exit(EXIT_FAILURE);
}
for (;;)
{
recsize = recvfrom(sock,
(void *)buffer,
1024,
0,
(struct sockaddr *)&sa,
&fromlen);
if (recsize < 0)
fprintf(stderr, "%s\n", strerror(errno));
msg = [NSString stringWithFormat:#"%s", buffer];
NSLog(msg);
}
}
and the actual call is this:
[NSThread detachNewThreadSelector:#selector(startServer)
toTarget:self
withObject:nil];
I have a network application meant for a private LAN. I am doing my testing using loopback. When I test on the LAN the socket creation order does not matter. If I test using loop back 127.0.0.1 then there is a socket creation ordering issue. Why is it different on loop back?
Here are more details...
There is one server, and many client instances. The server is broad casting data over UDP. The clients receive the data and process it.
I need to have the network layer not care about the order in which either the server or clients start. It is hard to administer process creation for my case. The application instances should be able to start on the network in any order and just see the data broadcasted on the UDP port when it is sent.
But there is something in the way I setting up my UDP sockets which is forcing ordering to take place. I must start the clients, THEN start the server. If I start the clients AFTER the server doing the UDP broadcast, the client sockets do not receive the data. If I force a running server instance to tear down and rebuild its UDP socket, suddenly all the clients start receiving data.
There must be something wrong with how I creating the socket. The client and server code use a shared function library to make the UDP socket. So the server is sending on m_fdOut. Each instance of the client is receiving on m_fdIn.
What am I doing wrong here?
SOCKET m_fdIn;
SOCKET m_fdOut;
if ((m_fdIn = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0)
{
WARNF("socket failed, winsock error %d\n", WSAGetLastError());
exit(1);
}
if ((m_fdOut = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0)
{
WARNF("socket failed, winsock error %d\n", WSAGetLastError());
exit(1);
}
int sockopt = 1;
if (setsockopt(m_fdOut, SOL_SOCKET, SO_BROADCAST, (char *)&sockopt,
sizeof(sockopt)) < 0)
{
WARNF("setsockopt failed, winsock error %d\n", WSAGetLastError());
exit(1);
}
sockopt = readPreference<int>("SOL_RCVBUF", 512*1024);
if (setsockopt(m_fdIn, SOL_SOCKET, SO_RCVBUF, (char *)&sockopt, sizeof(sockopt)) < 0)
{
WARNF("setsockopt failed, winsock error %d\n", WSAGetLastError());
exit(1);
}
sockopt = 1;
if (setsockopt(m_fdIn, SOL_SOCKET, SO_REUSEADDR, (char *)&sockopt, sizeof(sockopt)) < 0)
{
WARNF("setsockopt failed, winsock error %d\n", WSAGetLastError());
exit(1);
}
sockopt = readPreference<int>("IP_MULTICAST_TTL", 32);
if (setsockopt(m_fdOut, IPPROTO_IP, IP_MULTICAST_TTL, (char *)&sockopt, sizeof(sockopt)) < 0)
{
WARNF("setsockopt failed, winsock error %d\n", WSAGetLastError());
exit(1);
}
String destAdd = "255.255.255.255"
int portNumber = 1234;
int n1, n2, n3 ,n4;
if (sscanf(destAddr, "%d.%d.%d.%d", &n1, &n2, &n3, &n4) != 4)
{
n1 = n2 = n3 = n4 = 255;
}
u_long bcastAddr = (n1<<24) | (n2<<16) | (n3<<8) | n4;
outAddr.sin_family = AF_INET;
outAddr.sin_port = htons(portNumber);
outAddr.sin_addr.s_addr = htonl(bcastAddr);
struct sockaddr_in in_name;
in_name.sin_family = AF_INET;
in_name.sin_addr.s_addr = INADDR_ANY;
in_name.sin_port = htons(portNumber);
if (bind(m_fdIn, (struct sockaddr *)&in_name, sizeof(in_name)) < 0)
{
WARNF("bind failed, winsock error %d\n", WSAGetLastError());
exit(1);
}
So I did change the implementation from UDP broadcast to multicast. That seems to work in loopback so multiple processes can share the port.
I'm trying to implement simple traceroute for the iOS. Everything seems to work fine, except that somehow when I run my application on simulator or on the device it finds only a few (6-7) first routers on the way when the CLI traceroute finds all 14 routers.
const char *c = "www.gmail.com";
struct hostent *host_entry = gethostbyname(c);
char *ip_addr;
ip_addr = inet_ntoa(*((struct in_addr *)host_entry->h_addr_list[0]));
struct sockaddr_in destination, fromAddr;
int recv_sock;
int send_sock;
// Creting Sockets///
if ((recv_sock = socket(AF_INET, SOCK_DGRAM, IPPROTO_ICMP)) <
0) // using UDP socket.
{
NSLog(#"Could not cretae recv_sock.\n");
}
if ((send_sock = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
NSLog(#"Could not cretae send_sock.\n");
}
memset(&destination, 0, sizeof(destination));
destination.sin_family = AF_INET;
destination.sin_addr.s_addr = inet_addr(ip_addr);
destination.sin_port = htons(80);
struct timeval tv;
tv.tv_sec = 0;
tv.tv_usec = 10000;
setsockopt(recv_sock, SOL_SOCKET, SO_RCVTIMEO, (char *)&tv,
sizeof(struct timeval));
char *cmsg = "GET / HTTP/1.1\r\n\r\n";
int max_ttl = 20;
int num_attempts = 5;
socklen_t n = sizeof(fromAddr);
char buf[100];
for (int ttl = 1; ttl <= max_ttl; ttl++) {
memset(&fromAddr, 0, sizeof(fromAddr));
if (setsockopt(send_sock, IPPROTO_IP, IP_TTL, &ttl, sizeof(ttl)) < 0)
NSLog(#"error in setsockopt\n");
for (int try = 0; try < num_attempts; try ++) {
if (sendto(send_sock, cmsg, sizeof(cmsg), 0,
(struct sockaddr *)&destination,
sizeof(destination)) != sizeof(cmsg))
NSLog(#"error in send to...\n#");
int res = 0;
if ((res = recvfrom(recv_sock, buf, 100, 0, (struct sockaddr *)&fromAddr,
&n)) < 0) {
NSLog(#"an error: %s; recvfrom returned %d\n", strerror(errno), res);
} else {
char display[16] = {0};
inet_ntop(AF_INET, &fromAddr.sin_addr.s_addr, display, sizeof(display));
NSLog(#"Received packet from%s for TTL=%d\n", display, ttl);
break;
}
}
}
I have tried to bind the send socket but have same results and I can't use Sock_raw on iOS. I tried to run it on my mac and got same results. The error I get is "Resource temporarily unavailable;" for the recvfrom(). Why is that? How can I fix it?
The EAGAIN error ( producing "Resource temporarily unavailable;" string) could be raised by the timeout of the receiving socket.
Since you set just 10000 microseconds as read timeout (that's really short IMHO) with this line...
struct timeval tv;
tv.tv_sec = 0;
tv.tv_usec = 10000;
setsockopt(recv_sock, SOL_SOCKET, SO_RCVTIMEO, (char *)&tv,sizeof(struct timeval));
... it's possibile that the longer the way (i mean the number of router you have to pass through), the more chance you have to incour in this situation.
Try to raise timeout value and let us know if it got better.
EDIT
I tried the source code under linux and i noticed two kind of problems.
As mentioned above: Timeouts
Problem with the 80 port
I just raised the timeout and used a port different than 80 (in my case i sent udp message to 40000 port) and i got back all the hops just like traceroute command.
I'm not sure why this behaviour occour. Maybe some kind of "possible malicious packet alarm" gets triggered by the router that discards it
FURTHER EDIT
Look at this link: man traceroute
In the List Of Available Methods section you can find many ways to achieve what you need. Your method is similar to the default one, stating:
Probe packets are udp datagrams with so-called "unlikely" destination ports. The "unlikely" port of the first probe is 33434, then for each next probe it is incremented by one. Since the ports are expected to be unused, the destination host normally returns "icmp unreach port" as a final response. (Nobody knows what happens when some application listens for such ports, though).
So, if you need to full emulate the behaviour of the common Linux traceroute you have to increase by 1 the destination port, everytime the TTL increase (or everytime you can't get a response IMHO)
MAYBE, sometimes your command doesn't work on certain ports because the router is listening to the latter (as suggested by Linux manual and underlined in bold by me).
I am trying to use Libnet11 function:
int libnet_write_raw_ipv6 (libnet_t *l, u_int8_t *packet, u_int32_t size)
to inject IPv6 packet on network layer.
I had created IPv6 packet and captured it
with Wireshark. Wireshark reported:
malformed packet(wireshark says that next
header value in IPv6 is wrong and payload
size is too big in my opinion)
I hope, someone could help me with minimal code example,
showing how to manually build IPv6 packet (with ICMPv6
extension header) with libnet11 (libnet_write_raw_ipv6()).
I assume that the minimal code might look like this:
packet_len = 40 + 16; // 40B ~ IPv6 packet, 16B ~ ICMPv6 header
u_char *buf = NULL;
struct ip6_hdr *ip6 = NULL;
struct icmp6_hdr *icmp6 = NULL;
l = libnet_init();
if ( (buf = malloc(packet_len)) == NULL ) {
// error
}
// create IPv6 header
ip6 = (struct ip6_hdr *) buf;
ip6->ip6_flow = 0;
ip6->ip6_vfc = 6 << 4;
ip6->ip6_plen = 16; // ICMPv6 packet size
ip6->ip6_nxt = IPPROTO_ICMPV6; // 0x3a
ip6->ip6_hlim = 64;
memcpy(&(ip6->ip6_src), &src_addr, sizeof(struct in6_addr));
memcpy(&(ip6->ip6_dst), &dst_addr, sizeof(struct in6_addr));
// create ICMPv6 header
icmp6 = (struct icmp6_hdr *) (buf + 40); // 40B ~ IPv6 packet size
icmp6->icmp6_type = ICMP6_ECHO_REQUEST;
icmp6->icmp6_code = 0;
icmp6->icmp6_cksum= 0;
icmp6->icmp6_data32[0] = 0;
libnet_do_checksum(l, (u_int8_t *)buf, IPPROTO_ICMPV6, packet_len);
written = libnet_write_raw_ipv6(l, buf, packet_len);
if ( written != packet_len )
perror("Failed to send packet");
libnet_destroy(l);
free(buf);
I tried to find code examples but with no success.
Thank you in advance.
Martin
If you're using C++, then I'd recommend you libtins, a packet crafting a sniffing library. This short snippet does exactly what you want:
#include <tins/tins.h>
using namespace Tins;
void test(const IPv6Address &dst, const IPv6Address &src) {
PacketSender sender;
IPv6 ipv6 = IPv6(dst, src) / ICMPv6();
ipv6.hop_limit(64);
sender.send(ipv6);
}
int main() {
// now use it
test("f0ef:1234::1", "f000::1");
}
You can create it with raw sockets though. I also had to do something similar but couldn't find anything as a reference.
To do it with raw sockets, this link gives you a nice explanation