socket programming: 'accept: Bad file descriptor'

I'm trying to write a game that will let multiple clients connect and play - below is the relevant code (it's very messy - cleaning up later): Edit: I realized it's a lot of scrolling... the crash occurs towards the end of the game during: ``` std::cout << black_hits << " black hits & " << white_hits << " white hits.\n"; if (black_hits == 4) { std::cout << "you won!\n"; std::cin.ignore().get(); close(client); //<<<< CRASH HERE return 0; } ``` Not really a crash I guess... but close enough :) ``` #include <iostream> #include <vector> #include <algorithm> #include <cstdlib> #include <ctime> #include <string> #include <sstream> #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <errno.h> #include <string.h> #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #include <netdb.h> #include <arpa/inet.h> #include <sys/wait.h> #include <signal.h> #define BACKLOG 10 #define MAXDATASIZE 100 typedef enum {RED,GREEN,BLUE,YELLOW,ORANGE} color; int StartMasterMind(int client, sockaddr_storage addr_in); struct msgstruct { int length; char* send_data; }; void sigchld_handler(int s) { while(waitpid(-1, NULL, WNOHANG) > 0); } // get sockaddr, IPv4 or IPv6: void *get_in_addr(struct sockaddr *sa) { if (sa->sa_family == AF_INET) { return &(((struct sockaddr_in*)sa)->sin_addr); } return &(((struct sockaddr_in6*)sa)->sin6_addr); } int tcp_connect(const char *serv, const char *host = NULL) { int sockfd, new_fd; // listen on sock_fd, new connection on new_fd struct addrinfo hints, *servinfo, *p; struct sockaddr_storage their_addr; // connector's address information socklen_t sin_size; struct sigaction sa; int yes=1; char s[INET6_ADDRSTRLEN]; int rv; memset(&hints, 0, sizeof hints); hints.ai_family = AF_UNSPEC; hints.ai_socktype = SOCK_STREAM; hints.ai_flags = AI_PASSIVE; // use my IP if ((rv = getaddrinfo(host, serv, &hints, &servinfo)) != 0) { fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv)); return 1; } // loop through all the results and bind to the first we can for(p = servinfo; p != NULL; p = p->ai_next) { if ((sockfd = socket(p->ai_family, p->ai_socktype, p->ai_protocol)) == -1) { perror("server: socket"); continue; } if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(int)) == -1) { perror("setsockopt"); exit(1); } if (bind(sockfd, p->ai_addr, p->ai_addrlen) == -1) { close(sockfd); perror("server: bind"); continue; } break; } if (p == NULL) { fprintf(stderr, "server: failed to bind\n"); return 2; } freeaddrinfo(servinfo); // all done with this structure if (listen(sockfd, BACKLOG) == -1) { perror("listen"); exit(1); } sa.sa_handler = sigchld_handler; // reap all dead processes sigemptyset(&sa.sa_mask); sa.sa_flags = SA_RESTART; if (sigaction(SIGCHLD, &sa, NULL) == -1) { perror("sigaction"); exit(1); } printf("server: waiting for connections...\n"); while(1) { // main accept() loop sin_size = sizeof their_addr; new_fd = accept(sockfd, (struct sockaddr *)&their_addr, &sin_size); if (new_fd == -1) { perror("accept"); continue; } inet_ntop(their_addr.ss_family, get_in_addr((struct sockaddr *)&their_addr), s, sizeof s); printf("server: got connection from %s\n", s); if (!fork()) { // this is the child process close(sockfd); // child doesn't need the listener //if (send(new_fd, "Hello, world!", 13, 0) == -1) // perror("send"); //close(new_fd); StartMasterMind(new_fd,their_addr); // exit(0); } close(new_fd); // parent doesn't need this } return 0; } void InitializeGame(const char* port) { tcp_connect(port); } std::vector<color> GetInputAsColorMap(char* input) { [...]//redacted for clarity } int StartMasterMind(int client, sockaddr_storage addr_in) { struct msgstruct message; struct sockaddr_storage their_addr = addr_in; socklen_t addr_len; message.send_data = "Welcome to ... M A S T E R M I N D.\n"; message.length = strlen(message.send_data); send(client, message.send_data, message.length, 0); [...]//redacted for clarity if (strcmp(theValue, "random") == 0 || strcmp(theValue, "Random") == 0) { [...]//redacted for clarity } else { [...]//redacted for clarity } char* buf; for (int i = 0; i < 8; ++i) { std::vector<color> current_try(4); int black_hits = 0, white_hits = 0; std::vector<int> correctColorIndex; std::vector<int> correctColor; bool exclude[4] = {false}; std::cout << "test\n"; message.send_data = "Please enter your guess: "; message.length = strlen(message.send_data); send(client, message.send_data, message.length, 0); addr_len = sizeof their_addr; std::cout << "addr_len: " << addr_len << std::endl; recvfrom(client, buf, MAXDATASIZE-1, 0, (struct sockaddr *)&their_addr, &addr_len); current_try = GetInputAsColorMap(buf); std::cout << "the buffer: " << buf << std::endl; std::cout << "current_try: " << current_try[0] << current_try[1] << current_try[2] << current_try[3] << std::endl; [...]//redacted for clarity std::cout << black_hits << " black hits & " << white_hits << " white hits.\n"; if (black_hits == 4) { std::cout << "you won!\n"; std::cin.ignore().get(); close(client); //<<<< CRASH HERE return 0; } } [...]//redacted for clarity } int main(int argc, char** argv) { InitializeGame(argv[1]); return 0; } ``` Here is sample output: ``` server: waiting for connections... server: got connection from 127.0.0.1 value or random: 1122 test addr_len: 128 the buffer: 1123� current_try: 1123 3 black hits & 0 white hits. test addr_len: 128 the buffer: 1223� current_try: 1223 2 black hits & 1 white hits. test addr_len: 128 the buffer: 1122� current_try: 1122 4 black hits & 0 white hits. you won! accept: Bad file descriptor accept: Bad file descriptor accept: Bad file descriptor ... // continuously, hundreds of times ``` I'm very new to socket programming; could someone give me a hand? This crashes with or without trying to `close(client)` at the end of the game.