509 lines
13 KiB
C
509 lines
13 KiB
C
/*
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* This program listens for results sent by OwlPS Positioning on a UDP
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* socket, and listens for a client on a TCP socket. The client is
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* expected to send an HTTP GET request, with the request string as the
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* first variable value (the variable name does not matter).
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* For example, a correct request is detected if you load
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* http://localhost:8080/?request=ReadSimpleResults
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* (assuming the host running this program is localhost).
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*
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* The UDP listening port is the port on which OwlPS Positioning sends
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* result by default.
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* The TCP listening port is 8080.
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*
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* Only the last result read from the positioning server, for each
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* mobile, is memorised and provided to the HTTP client.
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*
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* The HTTP requests currently implemented are listed bellow.
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*
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* ** Request "ReadResults" **
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* Answer in case of error:
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* Results;NOK;Explanation
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* Normal answer:
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* Results;OK;Nb_results;Result_1;…;Result_n
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* Nb_results is the number of results in the answer (number of mobiles).
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* Result_i follows this format:
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* Mobile_MAC;Request_type;Request_timestamp;Nb_algo;Algo_1;…;Algo_n
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* Nb_algo is the number of algorithms in the result.
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* Algo_i follows this format:
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* Algorithm_name;X;Y;Z;Error;Area_name
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* Error is the distance from the true coordinates of the mobile, if
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* known; if unknown, Error is set to -1.
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* Area_name is the name of the area or room in which the mobile is (may
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* be empty).
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*
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* ** Unknown request **
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* If a unknown request is received, the answer format is:
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* UnknownRequest;NOK
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*
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* ** Request "ReadSimpleResults" **
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* Answer in case of error:
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* SimpleResults;NOK;Explanation
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* Normal answer:
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* SimpleResults;OK;Nb_results;Result_1;…;Result_n
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* Nb_results is the number of results in the answer (number of mobiles).
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* Result_i follows this format:
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* Mobile_MAC;X;Y;Z;Area_name
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* Area_name is the name of the area or room in which the mobile is (may
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* be empty).
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*/
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#include "owlps-udp-to-http.h"
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#include <signal.h>
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#include <semaphore.h>
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#include <pthread.h>
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#include <unistd.h>
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#include <stdlib.h>
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#include <strings.h>
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#include <string.h>
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#include <assert.h>
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char *program_name = NULL ;
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results_list *results = NULL ;
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unsigned int nb_results = 0 ;
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sem_t lock_results ;
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int udp_sockfd = -1 ;
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int tcp_sockfd = -1 ;
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char *answer = NULL ; // Answer to send to the client
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size_t answer_strlen = 0 ; // Total size of the answer string
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size_t answer_buflen = 0 ; // Size of the answer allocated buffer
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int main(int argc, char *argv[])
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{
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struct sigaction action ; // Signal handler structure
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int ret = 0 ; // Program return value
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pthread_t tcp_server_thread ;
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program_name = argv[0] ;
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owl_run = owl_true ;
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if (argc > 1)
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fprintf(stderr,
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"Sorry, this program does not take any argument yet.\n") ;
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/* Set up signal handlers */
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action.sa_flags = 0 ;
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sigemptyset(&action.sa_mask) ;
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action.sa_handler = owl_sigint_handler ;
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sigaction(SIGINT, &action, NULL) ;
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action.sa_handler = owl_sigterm_handler ;
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sigaction(SIGTERM, &action, NULL) ;
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/* Set up the semaphore */
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sem_init(&lock_results, 0, 1) ;
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/* Prepare the TCP socket */
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ret = init_tcp_socket() ;
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if (ret)
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goto exit ;
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/* Launch the TCP thread */
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ret = pthread_create(&tcp_server_thread, NULL,
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&tcp_server, NULL) ;
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if (ret)
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{
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perror("Cannot create the TCP server thread") ;
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ret = 1 ;
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goto exit ;
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}
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/* Main loop */
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ret = receive_udp() ;
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/* Stop the TCP thread */
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// We must cancel the thread because it can be blocked on the
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// recv() call:
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if (pthread_cancel(tcp_server_thread))
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perror("Cannot cancel the TCP server thread") ;
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if (pthread_join(tcp_server_thread, NULL))
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perror("Cannot join the TCP server thread") ;
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exit:
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/* Close sockets */
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if (tcp_sockfd >= 0)
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if (close(tcp_sockfd))
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perror("Error closing the TCP socket") ;
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if (udp_sockfd >= 0)
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if (close(udp_sockfd))
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perror("Error closing the UDP socket") ;
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/* Last cleaning */
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free(answer) ;
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free_results_list() ;
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sem_destroy(&lock_results) ;
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printf("%s: end.\n", program_name) ;
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return ret ;
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}
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/*
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* Opens the UDP socket and reads from it the results sent by OwlPS
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* Positioning.
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* Returns a non-zero value in case of error.
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*/
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int receive_udp()
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{
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owl_result *result ;
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/* Open the UDP socket */
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udp_sockfd = owl_create_udp_listening_socket(OWL_DEFAULT_RESULT_PORT) ;
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if (udp_sockfd < 0)
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return 1 ;
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/* UDP read loop */
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while (owl_run)
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{
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result = owl_receive_position(udp_sockfd) ;
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if (result == NULL)
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return 1 ;
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owl_print_result(result) ;
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store_result(result) ;
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printf("--------------\n") ;
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}
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return 0 ;
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}
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/*
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* Adds a new owl_result to the results' list.
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*/
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void store_result(owl_result *new_result)
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{
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sem_wait(&lock_results) ;
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// The results' list does not exist yet
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if (! results)
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{
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results = malloc(sizeof(results_list)) ;
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++nb_results ;
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results->result = new_result ;
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results->next = NULL ;
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}
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// The results' list contains at least 1 element
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else
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{
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// Search for an existing result with the same mobile's MAC
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results_list *res = results ;
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while (res != NULL)
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{
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char *mac = res->result->mobile_mac_addr ;
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if (strncmp(mac, new_result->mobile_mac_addr,
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OWL_ETHER_ADDR_STRLEN) == 0)
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break ;
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res = res->next ;
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}
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if (res == NULL) // Not found, adding an element
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{
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res = malloc(sizeof(results_list)) ;
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++nb_results ;
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res->next = results ;
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results = res ;
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}
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else // Found, clearing it
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owl_free_result(res->result) ;
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res->result = new_result ;
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}
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sem_post(&lock_results) ;
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}
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/*
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* Opens the TCP socket.
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* Returns a non-zero value in case of error.
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*/
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int init_tcp_socket()
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{
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struct sockaddr_in server_addr ;
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tcp_sockfd = socket(AF_INET, SOCK_STREAM, 0) ;
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if (tcp_sockfd < 0)
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{
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perror("Error opening the TCP socket") ;
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return tcp_sockfd ;
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}
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bzero((char *) &server_addr, sizeof(server_addr)) ;
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server_addr.sin_family = AF_INET ;
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server_addr.sin_addr.s_addr = INADDR_ANY ;
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server_addr.sin_port = htons(TCP_PORT) ;
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if (bind(tcp_sockfd, (struct sockaddr *) &server_addr,
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sizeof(server_addr)) < 0)
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{
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perror("Error binding the TCP socket") ;
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return -1 ;
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}
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return 0 ;
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}
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/*
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* Waits for requests from HTTP clients.
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*/
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void* tcp_server(void *NULL_value)
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{
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int newsockfd ;
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socklen_t client_len ;
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struct sockaddr_in client_addr ;
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ssize_t nbytes ; // recv/send return value
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char client_message[CLIENT_MESSAGE_STRLEN] ;
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char client_request[CLIENT_REQUEST_STRLEN] ;
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int request_id ;
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listen(tcp_sockfd, NB_CONNECTIONS) ;
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client_len = sizeof(client_addr) ;
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// Prepare the answer, assuming there is only 1 full result (an error
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// message will also fit)
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answer_buflen = ANSWER_HDR_STRLEN + OWL_CSV_RESULT_STRLEN ;
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answer = malloc(answer_buflen) ;
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strncpy(answer, ANSWER_HDR, ANSWER_HDR_STRLEN) ;
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while (owl_run)
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{
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newsockfd = accept(tcp_sockfd,
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(struct sockaddr*) &client_addr, &client_len) ;
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if (newsockfd < 0)
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{
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perror("Error accepting a connection on the TCP socket") ;
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continue ;
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}
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nbytes =
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recv(newsockfd, client_message, CLIENT_MESSAGE_STRLEN, 0) ;
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if (nbytes < 0)
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{
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perror("Error reading from the TCP socket") ;
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close(newsockfd) ;
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continue ;
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}
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client_message[nbytes] = '\0' ;
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#ifdef DEBUG
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printf("Got a message from the client:\n"
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"\"%s\"\n", client_message) ;
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#endif // DEBUG
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request_id =
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extract_request_from_message(client_request, client_message) ;
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prepare_answer(request_id) ;
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#ifdef DEBUG
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printf("Answer to send:\n\"%s\"\n", answer) ;
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#endif // DEBUG
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/* Send the answer */
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nbytes = send(newsockfd, answer, answer_strlen, 0) ;
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if (nbytes < 0)
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perror("Error sending answer to the TCP socket") ;
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close(newsockfd) ;
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}
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pthread_exit(NULL_value) ;
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}
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int
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extract_request_from_message(char client_request[CLIENT_REQUEST_STRLEN],
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char *client_message)
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{
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char *token ;
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token = strchr(client_message, '=') ;
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if (! token)
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return 0 ;
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++token ;
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token = strsep(&token, " ") ;
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if (strncmp(SIMPLE_RESULTS_REQUEST, token,
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strlen(SIMPLE_RESULTS_REQUEST)) == 0)
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{
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strncpy(client_request, SIMPLE_RESULTS_REQUEST,
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CLIENT_REQUEST_STRLEN) ;
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return SIMPLE_RESULTS_ID ;
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}
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if (strncmp(RESULTS_REQUEST, token,
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strlen(RESULTS_REQUEST)) == 0)
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{
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strncpy(client_request, RESULTS_REQUEST,
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CLIENT_REQUEST_STRLEN) ;
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return RESULTS_ID ;
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}
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return 0 ; // No known request found
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}
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/*
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* Prepare the answer string to send to the TCP client.
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*/
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void prepare_answer(int request_id)
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{
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// Reset the answer's length:
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answer_strlen = ANSWER_HDR_STRLEN ;
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switch (request_id)
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{
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case RESULTS_ID:
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strncpy(answer + answer_strlen, RESULTS_ANSWER,
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strlen(RESULTS_ANSWER)) ;
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answer_strlen += strlen(RESULTS_ANSWER) ;
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sem_wait(&lock_results) ;
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if (! results)
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{
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char answer_end[] = ";NOK;NoResult" ;
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strncpy(answer + answer_strlen, answer_end,
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strlen(answer_end)) ;
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answer_strlen += strlen(answer_end) ;
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}
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else
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{
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results_list *result ;
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char answer_begin[10] ;
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size_t answer_begin_len ;
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snprintf(answer_begin, 10, ";OK;%u", nb_results) ;
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answer_begin_len = strlen(answer_begin) ;
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strncpy(answer + answer_strlen, answer_begin,
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answer_begin_len) ;
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answer_strlen += answer_begin_len ;
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realloc_answer(answer_strlen +
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nb_results * OWL_CSV_RESULT_STRLEN) ;
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result = results ;
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while (result != NULL)
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{
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char result_str[OWL_CSV_RESULT_STRLEN] ;
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size_t result_len ;
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owl_result_to_csv(result_str, result->result) ;
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result_len = strlen(result_str) ;
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answer[answer_strlen++] = ';' ;
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assert(answer_strlen<answer_buflen) ;
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strncpy(answer + answer_strlen, result_str,
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result_len) ;
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answer_strlen += result_len ;
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result = result->next ;
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}
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}
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sem_post(&lock_results) ;
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break ;
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case SIMPLE_RESULTS_ID:
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strncpy(answer + answer_strlen, SIMPLE_RESULTS_ANSWER,
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strlen(SIMPLE_RESULTS_ANSWER)) ;
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answer_strlen += strlen(SIMPLE_RESULTS_ANSWER) ;
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sem_wait(&lock_results) ;
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if (! results)
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{
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char answer_end[] = ";NOK;NoResult" ;
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strncpy(answer + answer_strlen, answer_end,
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strlen(answer_end)) ;
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answer_strlen += strlen(answer_end) ;
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}
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else
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{
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results_list *result ;
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char answer_begin[10] ;
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size_t answer_begin_len ;
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snprintf(answer_begin, 10, ";OK;%u", nb_results) ;
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answer_begin_len = strlen(answer_begin) ;
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strncpy(answer + answer_strlen, answer_begin,
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answer_begin_len) ;
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answer_strlen += answer_begin_len ;
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realloc_answer(answer_strlen +
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nb_results * OWL_CSV_RESULT_SIMPLE_STRLEN) ;
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result = results ;
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while (result != NULL)
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{
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char result_str[OWL_CSV_RESULT_SIMPLE_STRLEN] ;
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size_t result_len ;
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owl_result_to_csv_simple(result_str, result->result) ;
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result_len = strlen(result_str) ;
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answer[answer_strlen++] = ';' ;
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strncpy(answer + answer_strlen, result_str,
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result_len) ;
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answer_strlen += result_len ;
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result = result->next ;
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}
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}
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sem_post(&lock_results) ;
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break ;
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default:
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{
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char answer_end[] = "UnknownRequest;NOK" ;
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strncpy(answer + ANSWER_HDR_STRLEN, answer_end,
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strlen(answer_end)) ;
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answer_strlen += strlen(answer_end) ;
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}
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}
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answer[answer_strlen] = '\0' ;
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}
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/*
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* Realloc the answer buffer to the if needed: grows it if new_size is
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* greater than the current size, shrink it if the current size is
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* greater than the double of new_size.
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*/
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void realloc_answer(size_t new_size)
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{
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if (new_size > answer_buflen)
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answer_buflen = new_size ;
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else if (answer_buflen / 2 >= new_size)
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answer_buflen /= 2 ;
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else
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return ;
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answer = realloc(answer, answer_buflen) ;
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}
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/*
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* Frees the memory allocated for the results' list.
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*/
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void free_results_list()
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{
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results_list *tmp_res ;
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while (results != NULL)
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{
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owl_free_result(results->result) ;
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tmp_res = results ;
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results = results->next ;
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free(tmp_res) ;
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}
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nb_results = 0 ;
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}
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