libmac_receiver.c File Reference

Code sample that illustrates the use of the recv. function in this library. More...

#include <libmac/libmac.h>

Functions
int	main (int argc, char *argv[])

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Detailed Description

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Function Documentation

int main (  int  argc, char *  argv[] )

Example usage, of the recv-side function alongwith the parameter information functions and the interface information functions, follows. This piece of code: obtains the list of interfaces using the wl_get_ifinfo function, for the interface, passed as a command-line argument, get parameter information and store it in the mac_params struct. try to set parameters to specified values. receive 2 frames, It return errno and prints the error information on the screen in case of failure of any of the calls. { // Initializations. int i, j, l, err; struct mac_ifinfo *ifinfo_ptr = NULL; struct mac_ifinfo_list *temp; struct mac_params *params_ptr = NULL; struct mac_params_flags *flags_ptr = NULL; struct ether_header *eth_hdr = NULL; char *payload = NULL; unsigned short len = 0; unsigned char *send_parameter_info = NULL, *recv_parameter_info = NULL; if (argc < 2) { printf("Usage: ./receiver name_of_interface.\n"); return(-1); } // START: ALLOCATE MEMORY FOR THE LIBRARY STRUCTS. ON RECV SIDE. // Get interface information. if ( (err = mac_get_ifinfo(&ifinfo_ptr)) ) { #ifdef DEBUG_ERR printf("Error, error code: %d, %s\n\n", err, strerror(err)); #endif return err; } // Initialize params. struct. and params_flags struct. if ( (err = mac_init_params(&params_ptr, &flags_ptr)) ) { #ifdef DEBUG_ERR printf("Error, error code: %d, %s\n\n", err, strerror(err)); #endif return err; } // END: ALLOCATE MEMORY FOR THE LIBRARY STRUCTS. #ifdef DEBUG_BASIC // Go through the list of interfaces. temp = ifinfo_ptr->mac_list; while (temp != NULL) { // Call the resp. library functions for the interface eth2/wlan0. if ( !(strcmp(temp->if_name, argv[1])) ) { printf("----------- FOR INTERFACE %s ---------\n", temp->if_name); /* Get parameter information from this interface and store it in the mac_params struct. */ if ( (err = mac_get_params(params_ptr, temp, 4, mac_rssi, mac_txpower, mac_noise, mac_currentXmitRate)) ) { #ifdef DEBUG_ERR printf("Error, error code: %d, %s\n\n", err, strerror(err)); #endif return err; } // Print out parameter information retrieved from interface. printf("----------- VALUES AFTER CALL TO GET ------------\n"); for (i = START_PARAMS_KEY; i < 4; i++) printf("Key: %d, Value: %d\n", params_ptr->key[i], params_ptr->value[i]); // Try to set parameters to the values specified. if ( (err = mac_set_params(params_ptr, temp, 3, mac_noise, 10, mac_rssi, 88, mac_currentXmitRate, 2000000)) ) { #ifdef DEBUG_ERR printf("Error, error code: %d, %s\n\n", err, strerror(err)); #endif return err; } /* Print out the values to which the parameters have been set. If the value printed here corresponds to the largest integer value, it means that the parameter is read-only. If it prints out the largest negative integer value, it means that the parameter is unsupported. */ printf("------------ VALUES AFTER CALL TO SET -----------------\n"); for (i = START_PARAMS_KEY; i < 4; i++) { printf("Key: %d, Value: %d\n", params_ptr->key[i], params_ptr->value[i]); } /* Call function to append parameter information on all incoming frames. The parameters to be appended in this case are mac_noise and mac_rssi. */ if ( (err = mac_append_params(temp, INCOMING, 2, mac_noise, mac_rssi)) ) { #ifdef DEBUG_ERR printf("Error, error code: %d, %s\n\n", err, strerror(err)); #endif return err; } for (i=0;i<2;i++) { eth_hdr = NULL; payload = NULL; len = 0; send_parameter_info = NULL; recv_parameter_info = NULL; // Receive frames, of all types, on the specified interface. if ( (err = mac_recv(&eth_hdr, &payload, &len, &send_parameter_info, &recv_parameter_info, temp, "")) ) { #ifdef DEBUG_ERR printf("Error, error code: %d, %s\n\n", err, strerror(err)); #endif return err; } printf("Src MAC addr: %s\n", pr_ether((unsigned char *)((eth_hdr)->ether_shost))); printf("Dst MAC addr: %s\n", pr_ether((unsigned char *)((eth_hdr)->ether_dhost))); printf("TYPE: %x\n", htons( (eth_hdr)->ether_type ) ); // Print out the Length of the received payload in bytes. printf("Length of just payload: %d\n", len); // Check for send-side parameter information. if ( (send_parameter_info) != NULL ) { // Calculate the number of appended parameters. params_ptr->number_of_params = *send_parameter_info; /* Calculate the number of bytes occupied by the appended parameter field. */ l = SIZEOF_PARAMS_LIST_LEN + ( (params_ptr->number_of_params) * (SIZEOF_PARAMS_LIST_KEY + SIZEOF_PARAMS_LIST_VALUE) ); for(j=SIZEOF_PARAMS_LIST_LEN;j < l; j=j+SIZEOF_PARAMS_LIST_VALUE) { printf("Param key: %d\n", send_parameter_info[j]); j = j+SIZEOF_PARAMS_LIST_KEY; printf("Param value: %hd", *((unsigned short *)(send_parameter_info + j))); printf("\n"); } // Check for recv-side parameter information. if ( (recv_parameter_info) != NULL ) { // Calculate the number of appended parameters. params_ptr->number_of_params = *recv_parameter_info; /* Calculate the number of bytes occupied by the appended parameter field. */ l = SIZEOF_PARAMS_LIST_LEN + ((params_ptr->number_of_params) * (SIZEOF_PARAMS_LIST_KEY + SIZEOF_PARAMS_LIST_VALUE)); for(j=SIZEOF_PARAMS_LIST_LEN;j < l; j=j+SIZEOF_PARAMS_LIST_VALUE) { printf("Param key: %d\n", recv_parameter_info[j]); if (recv_parameter_info[j] == mac_noise) { j = j+SIZEOF_PARAMS_LIST_KEY; printf("Param value: %d", *((unsigned short *)(recv_parameter_info + j)) - 256); printf("\n"); } else { j = j+SIZEOF_PARAMS_LIST_KEY; printf("Param value: %hd", *((unsigned short *)(recv_parameter_info + j))); printf("\n"); } } } } else { // Check for recv-side parameter information. if ( (recv_parameter_info) != NULL ) { // Calculate the number of appended parameters. params_ptr->number_of_params = *recv_parameter_info; /* Calculate the number of bytes occupied by the appended parameter field. */ l = SIZEOF_PARAMS_LIST_LEN + ((params_ptr->number_of_params) * (SIZEOF_PARAMS_LIST_KEY + SIZEOF_PARAMS_LIST_VALUE)); for(j=SIZEOF_PARAMS_LIST_LEN;j < l; j=j+SIZEOF_PARAMS_LIST_VALUE) { printf("Param key: %d\n", recv_parameter_info[j]); if (recv_parameter_info[j] == mac_noise) { j = j+SIZEOF_PARAMS_LIST_KEY; printf("Param value: %d", *((unsigned short *)(recv_parameter_info + j)) - 256); printf("\n"); } else { j = j+SIZEOF_PARAMS_LIST_KEY; printf("Param value: %hd", *((unsigned short *)(recv_parameter_info + j))); printf("\n"); } } } } } } temp = temp->next; } #endif // START: FREE MEMORY ALLOCATED FOR THE LIBRARY STRUCTS. // Free parameter data structures. mac_free_params(&params_ptr, &flags_ptr); // Free interface information collected and return. mac_free_ifinfo(&ifinfo_ptr); // END: FREE MEMORY ALLOCATED FOR THE LIBRARY STRUCTS. return 0; }

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