I am using Socket programming to connect devices each other in iOS.
I want to get connected device's Host Name which is connected to a socket using CFSocketNativeHandle.
When other device connected to my Socket i get callback in following callback function:
static void serverAcceptCallback(CFSocketRef socket, CFSocketCallBackType type, CFDataRef address, const void *data, void *info)
{
// We can only process "connection accepted" calls here
if ( type != kCFSocketAcceptCallBack )
{
return;
}
// for an AcceptCallBack, the data parameter is a pointer to a CFSocketNativeHandle
CFSocketNativeHandle nativeSocketHandle = *(CFSocketNativeHandle*)data;
uint8_t name[SOCK_MAXADDRLEN];
socklen_t namelen = sizeof(name);
NSData *peer = nil;
if (0 == getpeername(nativeSocketHandle, (struct sockaddr *)name, &namelen)) {
peer = [NSData dataWithBytes:name length:namelen];
NSString *hostName = [[NSString alloc] initWithData:peer encoding:NSUTF8StringEncoding];
NSLog(#"HostName=%#",hostName);
}
}
Here I am getting NSData for "peer" but i am getting NSString *hostName=null.
How can i get exact Host name with this NSData.
getpeername() returns the address of the peer connected to the socket. You can access it using code below:
struct sockaddr_in addr ;
socklen_t len = sizeof(addr) ;
int res = getpeername(nativeSocketHandle, (struct sockaddr *)&addr, &len) ;
if (res == 0) {
char strAddr[20] ;
inet_ntop(AF_INET, &addr.sin_addr, strAddr, sizeof(strAddr)) ;
printf("ip %s\n", strAddr) ;
}
The only thing the socket knows is the IP address of the other end of the connection, so when you use getpeername it returns you the IP address. You will need to look up the IP address using either CFhost or POSIX calls - there are a squillion references to how to accomplish this using the POSIX APIs.
There is a very good chance that the other end will not be the same as the name of the device.
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 tried to hook iOS socket connect method to get the information of connected ports between the local host and remote server.
However, from the socket struct sockaddr, the sa_family is always AF_SYSTEM(kernel event message).
Hood code:
int (*origin_connect)(int socket, const struct sockaddr *address, socklen_t address_len);
int replaced_connect(int socket, const struct sockaddr *address, socklen_t address_len) {
int r = origin_connect(socket, address, address_len);
sa_family_t f = address->sa_family;
NSLog(#"CONNECT FAMILY %d", f);
if (f == AF_INET) {
struct sockaddr_in *addr = (struct sockaddr_in *)address;
NSString *remote_ip = [[NSString alloc]initWithCString:inet_ntoa(addr->sin_addr) encoding:NSUTF8StringEncoding];
uint16_t remote_port = ntohs(addr -> sin_port);
NSLog(#"The CONNECT ip = %# port = %u", remote_ip, remote_port);
struct sockaddr local_address;
socklen_t addr_size = sizeof(local_address);
getsockname(socket, &local_address, &addr_size);
struct sockaddr_in *laddr = (struct sockaddr_in*)&local_address;
NSString *local_ip = [[NSString alloc]initWithCString:inet_ntoa(laddr->sin_addr) encoding:NSUTF8StringEncoding];
uint16_t local_port = ntohs(laddr->sin_port);
NSLog(#"The CONNECT Local ip = %# port = %u", local_ip, local_port);
} else if (f == AF_SYSTEM) {
NSLog(#"hello there :(");
struct sockaddr_ctl * ctl = (struct sockaddr_ctl *)address;
}
return r;
}
Did I hook wrong method or is there any other way to get the connected ports information?
You're getting AF_SYSTEM hooked because when apps start, they also call on a system socket. If you allow your hook to just ignore that, the next calls should intercept TCP/IP Sockets.
There are, by the way, much better ways to do that. You can externally get information of connected sockets and even notifications, by using com.apple.network.statistics. A full sample of how to do so is at http://newosxbook.com/src.jl?tree=listings&file=lsock.c
I have to resolve the hostname of a device in my LAN from its ip address on this LAN.
I have some code that works for external ip address but not the internally connected devices .
Below i have attached the code .
if you have any idea to get hostname of remote machine from it's IP in iOS/OSX, it'll make my day.
int error;
struct addrinfo *results = NULL;
error = getaddrinfo("173.194.34.24", NULL, NULL, &results);
if (error != 0)
{
NSLog (#"Could not get any info for the address");
}
for (struct addrinfo *r = results; r; r = r->ai_next)
{
char hostname[NI_MAXHOST] = {0};
error = getnameinfo(r->ai_addr, r->ai_addrlen, hostname, sizeof hostname, NULL, 0 , 0);
if (error != 0)
{
continue; // try next one
}
else
{
NSLog (#"Found hostname: %s", hostname);
break;
}
}
freeaddrinfo(results);
or with NSHost
NSLog(#"%# \n%#",[NSHost currentHost],[[NSHost hostWithAddress:#"172.17.241.61"] names]);
Only way to make a DNS lookup directly to a specific DNS is to implement the protocol yourself or use some library.
https://serverfault.com/questions/173187/what-does-a-dns-request-look-like
https://www.ietf.org/rfc/rfc1035.txt
https://github.com/adeboer/rfc1035lib
I have written a server that listens on a specific port for incoming tcp connections. To manage the network connectivity I am using Streams (CFStream/NSStream). When a connection is esthablished I save all the information about this very connection in another instance of a dedicated class which is also set as the delegate for the streams.
Now I want to get the public IP of the device that sends me a message through the already esthablished streams, in other words, I would like to store the IP of the stream's peer. I tried many things, but unfortunately I only get null-values.
Is there a possibility to get the peer's address (ip and port) from an existing stream of the described form?
Here is some code I have tried:
CFDataRef peerAddress = CFSocketCopyPeerAddress(_sockRef);
// _sockRef is saved when connection is established in listening callback and is not null
I also tried to get the information direct in the listening callback method:
NSData *peer = nil;
CFSocketNativeHandle nativeSocketHandle = *(CFSocketNativeHandle *)data;
struct sockaddr *addressinfo = NULL;
uint8_t name[SOCK_MAXADDRLEN];
socklen_t namelen = sizeof(addressinfo);
int result = getpeername(nativeSocketHandle, addressinfo, &namelen);
if (result == 0) {
peer = [NSData dataWithBytes:name length:namelen];
}
struct sockaddr_in *s = (struct sockaddr_in*)name;
char *ipstr = malloc(INET_ADDRSTRLEN);
ipstr = inet_ntoa(s->sin_addr); // is 0.0.0.0 :-(
And I tried another method:
_publicIP = CFWriteStreamCopyProperty((__bridge CFWriteStreamRef)(_writeStream), kCFStreamPropertySocketRemoteHostName);
Why do I always get null-values? Can anyone help me?
Thank you in advance!
Okay I figured it out by now. This is what I did:
- (void)getPublicClientAddress {
// Get public IP from stream
// Get hands on appropriate data structures via the socket number
CFSocketNativeHandle nativeSocketHandle = _socketnumber;
uint8_t name[SOCK_MAXADDRLEN];
socklen_t namelen = sizeof(name);
NSData *peer = nil;
if (0 == getpeername(nativeSocketHandle, (struct sockaddr *)name, &namelen)) {
peer = [NSData dataWithBytes:name length:namelen];
}
if (_ipv6){
// If ipv6 is used
struct sockaddr_in6 *socketaddress = (struct sockaddr_in6*)name;
// convert ip to string
char *ipstr = malloc(INET6_ADDRSTRLEN);
struct in6_addr *ipv6addr = &socketaddress->sin6_addr;
inet_ntop(AF_INET6, ipv6addr, ipstr, sizeof(ipstr));
// convert port to int
int portnumber = socketaddress->sin6_port;
// Save in properties
_publicIP = [NSString stringWithFormat:#"%s", ipstr];
_publicPort = [NSString stringWithFormat:#"%d", portnumber];
} else {
// If ipv4 is used
struct sockaddr_in *socketaddress = (struct sockaddr_in*)name;
// convert ip to string
char *ipstr = malloc(INET_ADDRSTRLEN);
struct in_addr *ipv4addr = &socketaddress->sin_addr;
ipstr = inet_ntoa(*ipv4addr);
//inet_ntop(AF_INET, ipv4addr, ipstr, sizeof(ipstr));
// convert port to int
int portnumber = socketaddress->sin_port;
// Save in properties
_publicIP = [NSString stringWithFormat:#"%s", ipstr];
_publicPort = [NSString stringWithFormat:#"%d", portnumber];
}
}
Afterwards you will have the public IP in the property _publicIP and the public port in the property _publicPort. All information is gathered from a connection on the server side.
I hope this post will help someone =)
in iOS CFSocket the way handle callback function is as followed
void receiveData(CFSocketRef s,
CFSocketCallBackType type,
CFDataRef address,
const void *data,
void *info)
{
}
int main ()
{
CFSocketRef s = CFSocketCreate(NULL, PF_INET,
SOCK_STREAM, IPPROTO_TCP,
kCFSocketDataCallBack,
receiveData,
NULL);
struct sockaddr_in sin;
struct hostent *host;
host = gethostbyname("localhost");
memset(&sin, 0, sizeof(sin));
memcpy(&(sin.sin_addr), host->h_addr,host->h_length);
sin.sin_family = AF_INET;
sin.sin_port = htons(888);
CFDataRef address, data;
UInt8 message[] = "Hello world";
CFRunLoopSourceRef source;
address = CFDataCreate(NULL, (UInt8 *)&sin, sizeof(sin));
data = CFDataCreate(NULL, message, sizeof(message));
CFSocketConnectToAddress(s, address, 0);
CFSocketSendData(s, NULL, data, 0);
}
in CFSocket when we do a CFSocketCreate we put the callback function in the SocketCreate function.
But for C Code the Socket and read from Socket is as followed.
sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (connect(sockfd,(struct sockaddr *) &serv_addr,sizeof(serv_addr)) < 0)
error("ERROR connecting");
printf("Please enter the message: ");
bzero(buffer,256);
fgets(buffer,255,stdin);
n = write(sockfd,buffer,strlen(buffer));
if (n < 0)
error("ERROR writing to socket");
bzero(buffer,256);
n = read(sockfd,buffer,255);
I don't how to implement the callback read function inside the C Code. The callback function would be implemented every time something come into the buffer.
As you noted BSD sockets is not callback based, you need to poll from read to receive new data. You can call this periodically on the main thread or create a custom thread for reading data repeatedly.
CFSocket wraps BSD sockets at a higher level. It has some nice features, I believe that it automatically handles threading, and sleeps the thread until data is received. Reimplemnenting these features would not be a trivial process.
Good resources:
http://beej.us/guide/bgnet/
BSD Sockets - How to use non-blocking sockets?
http://man7.org/linux/man-pages/man2/poll.2.html