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C ++ - ping function without root access

I am trying to write a simple C ++ ping function to find out if the network address is responding. I don’t need ICMP on purpose, I just need to see if there is a server and what to answer. I do some research, and every solution I come up with requires a raw socket or something that requires the program to have access to sudo. I will not be able to guarantee that the system on which I am running this can change the network stack, so this is unacceptable.

Here are some related questions that I have already looked at.

It seems that ping requires root access for a good reason. I don’t want to deliberately create a security loophole, I just want to see if the server is responding. Is there a good C ++ function or resource that can do this? I will definitely send any trial solution that I came up with. I need a solution for Linux (BSD). Since almost every unix-like system runs SSH, I can even just test it against port 22. I plan to focus only on Linux-systems as a limitation.

thanks

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2 answers

Here is an example with popen . I would like to get a better solution, so if there is a socket or other method that does not resort to a shell call, I would really appreciate it. This should only work with g++ ping_demo.cpp -o ping_demo . Let me know if this causes compilation errors.

 // C++ Libraries #include <cstdio> #include <iostream> #include <sstream> #include <string> /** * @brief Convert String to Number */ template <typename TP> TP str2num( std::string const& value ){ std::stringstream sin; sin << value; TP output; sin >> output; return output; } /** * @brief Convert number to string */ template <typename TP> std::string num2str( TP const& value ){ std::stringstream sin; sin << value; return sin.str(); } /** * @brief Execute Generic Shell Command * * @param[in] command Command to execute. * @param[out] output Shell output. * @param[in] mode read/write access * * @return 0 for success, 1 otherwise. * */ int Execute_Command( const std::string& command, std::string& output, const std::string& mode = "r") { // Create the stringstream std::stringstream sout; // Run Popen FILE *in; char buff[512]; // Test output if(!(in = popen(command.c_str(), mode.c_str()))){ return 1; } // Parse output while(fgets(buff, sizeof(buff), in)!=NULL){ sout << buff; } // Close int exit_code = pclose(in); // set output output = sout.str(); // Return exit code return exit_code; } /** * @brief Ping * * @param[in] address Address to ping. * @param[in] max_attempts Number of attempts to try and ping. * @param[out] details Details of failure if one occurs. * * @return True if responsive, false otherwise. * * @note { I am redirecting stderr to stdout. I would recommend * capturing this information separately.} */ bool Ping( const std::string& address, const int& max_attempts, std::string& details ) { // Format a command string std::string command = "ping -c " + num2str(max_attempts) + " " + address + " 2>&1"; std::string output; // Execute the ping command int code = Execute_Command( command, details ); return (code == 0); } /** * @brief Main Function */ int main( int argc, char* argv[] ) { // Parse input if( argc < 2 ){ std::cerr << "usage: " << argv[0] << " <address> <max-attempts = 3>" << std::endl; return 1; } // Get the address std::string host = argv[1]; // Get the max attempts int max_attempts = 1; if( argc > 2 ){ max_attempts = str2num<int>(argv[2]); } if( max_attempts < 1 ){ std::cerr << "max-attempts must be > 0" << std::endl; return 1; } // Execute the command std::string details; bool result = Ping( host, max_attempts, details ); // Print the result std::cout << host << " "; if( result == true ){ std::cout << " is responding." << std::endl; } else{ std::cout << " is not responding. Cause: " << details << std::endl; } return 0; }

Sampling Outputs

 $> g++ ping_demo.cpp -o ping_demo $> # Valid Example $> ./ping_demo localhost localhost is responding. $> # Invalid Example $> ./ping_demo localhostt localhostt is not responding. Cause: ping: unknown host localhostt $> # Valid Example $> ./ping_demo 8.8.8.8 8.8.8.8 is responding.
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I created an easy-to-use ping class with the ability to add an Ethernet network port. I based the code on msmith81886, but wanted to condense for those who use it in the industry.

ping.hpp

 #ifndef __PING_HPP_ #define __PING_HPP_ #include <cstdio> #include <iostream> #include <sstream> #include <string> #include <fstream> #include <cerrno> #include <cstring> class system_ping { public: int test_connection (std::string ip_address, int max_attempts, bool check_eth_port = false, int eth_port_number = 0); private: int ping_ip_address(std::string ip_address, int max_attempts, std::string& details); }; #endif

ping.cpp

 #include "../include/ping.hpp" int system_ping::ping_ip_address(std::string ip_address, int max_attempts, std::string& details) { std::stringstream ss; std::string command; FILE *in; char buff[512]; int exit_code; try { command = "ping -c " + std::to_string(max_attempts) + " " + ip_address + " 2>&1"; if(!(in = popen(command.c_str(), "r"))) // open process as read only { std::cerr << __FILE__ << "(" << __FUNCTION__ << ":" << __LINE__ << ") | popen error = " << std::strerror(errno) << std::endl; return -1; } while(fgets(buff, sizeof(buff), in) != NULL) // put response into stream { ss << buff; } exit_code = pclose(in); // blocks until process is done; returns exit status of command details = ss.str(); } catch (const std::exception &e) { std::cerr << __FILE__ << "(" << __FUNCTION__ << ":" << __LINE__ << ") | e.what() = " << e.what() << std::endl; return -2; } return (exit_code == 0); } int system_ping::test_connection (std::string ip_address, int max_attempts, bool check_eth_port, int eth_port_number) { std::cout << __FILE__ << "(" << __FUNCTION__ << ":" << __LINE__ << ") | started" << std::endl; int eth_conn_status_int; std::string details; try { if (check_eth_port) { std::ifstream eth_conn_status ("/sys/class/net/eth" + std::to_string(eth_port_number) + "/carrier"); eth_conn_status >> eth_conn_status_int; // 0: not connected; 1: connected if (eth_conn_status_int != 1) { std::cerr << __FILE__ << "(" << __FUNCTION__ << ":" << __LINE__ << ") | eth" << std::to_string(eth_port_number) << " unplugged"; return -1; } } if (ping_ip_address(ip_address, max_attempts, details) != 1) { std::cerr << __FILE__ << "(" << __FUNCTION__ << ":" << __LINE__ << ") | cannot ping " << ip_address << " | " << details << std::endl; return -2; } } catch (const std::exception &e) { std::cerr << __FILE__ << "(" << __FUNCTION__ << ":" << __LINE__ << ") | e.what() = " << e.what() << std::endl; return -3; } std::cout << __FILE__ << "(" << __FUNCTION__ << ":" << __LINE__ << ") | ping " << ip_address << " OK" << std::endl; std::cout << __FILE__ << "(" << __FUNCTION__ << ":" << __LINE__ << ") | ended" << std::endl; return 0; }
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Source: https://habr.com/ru/post/987594/

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