root/vtcross/trunk/src/lib/socketcomm/socketcomm.cpp @ 174

/* Virginia Tech Cognitive Radio Open Source Systems
 * Virginia Tech, 2009
 *
 * TODO LICENSE INFORMATION GOES HERE
 */

/* TODO DESCRIPTION OF FILE.
 */


#include <cstdlib>
#include <cstring>
#include <netdb.h>
#include <netinet/in.h>
#include <stdint.h>
#include <string>
#include <sys/types.h>
#include <sys/socket.h>

#include "vtcross/common.h"
#include "vtcross/containers.h"
#include "vtcross/debug.h"
#include "vtcross/error.h"
#include "vtcross/socketcomm.h"


// TODO can someone write a description of how this function is operating? I'm
// not sure I understand why it is making two separate blocking calls to recv
void
ReadMessage(int32_t socketFD, char* msgBuffer)
{
    ssize_t msgLength = recv(socketFD, msgBuffer, 256, MSG_PEEK);

    size_t i;
    for(i = 0; i < 256; i++) {
            if(strcmp(&msgBuffer[i], "\0") == 0)
            break;
    }

    msgLength = recv(socketFD, msgBuffer, i + 1, 0);
    if (msgLength < 0)
        ERROR(1, "Error reading from socket");
}


int32_t 
ClientSocket(char* serverName, char* portNumber)
{
    int32_t socketFD;
    int32_t portNo;

    struct sockaddr_in serv_addr;
    struct hostent *server;
    
    server = gethostbyname(serverName);
    if(server == NULL)
        ERROR(1, "No server found by that hostname.");

    portNo = atoi(portNumber);

    socketFD = socket(AF_INET, SOCK_STREAM, 0);
    if(socketFD < 0) 
        ERROR(1, "Error opening socket");

    memset((void *) &serv_addr, 0, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_port = htons(portNo);
    memcpy((char *) &serv_addr.sin_addr.s_addr, (char *) server->h_addr, \
            server->h_length);

    if(connect(socketFD, (struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0) 
        ERROR(1, "Error connecting to remote socket.");

    return socketFD;
}

    
/*
int32_t
SendMessage(int32_t socketFD, char* message) 
{
     
    // TODO explain this. What, exactly, does the below line do and how does it
    // affect the rest of the function?
    strcat(message, "\0000");

    ssize_t numSentBytes = send(socketFD, message, (strlen(message) + 1), 0);
    if(numSentBytes < 0) {
        ERROR(1, "Error sending to server.");
    }
    else if(numSentBytes == 0) {
        LOG("socket_comm::SendMessage - Server closed the socket.\n");
    }
   
    return numSentBytes;
}
*/

// TODO this function is here to handle calls to send const char* messages. Note
// that the std::string.c_str() function auto-appends a null character at the
// end of the cstring, so the strcat function call in the previous function
// isn't necessary here... I think... although I still don't really understand
// what exactly that call is for.
int32_t
SendMessage(int32_t socketFD, const char* message) 
{
    ssize_t numSentBytes = send(socketFD, message, (strlen(message) + 1), 0);
    if(numSentBytes < 0) {
        ERROR(1, "Error sending to server.");
    }
    else if(numSentBytes == 0) {
        LOG("socket_comm::SendMessage - Server closed the socket.\n");
    }
   
    return numSentBytes;
}


// TODO This function is currently returning 1... always... is this necessary?
// If we want a fail/success return type, then why aren't we ever returning a
// failure?
int32_t 
GetParameter(int32_t socketFD, struct Parameter pList[], \
        struct CE_Info *ce_info)
{
    char buffer[256];
    memset(buffer, 0, 256);

    ReadMessage(socketFD, buffer);
    ce_info->numParameters = atoi(buffer);
    LOG("socket_comm::GetParameter - Number of parameters: %d\n", \
            ce_info->numParameters);
    
    for(size_t i = 0; i < ce_info->numParameters; i++) {
        memset(buffer, 0, 256);
        ReadMessage(socketFD, buffer);
        LOG("socket_comm::GetParameter - Name: %s\n", buffer);
        pList[i].name = std::string(buffer);
    
        memset(buffer, 0, 256);
        ReadMessage(socketFD, buffer);
        LOG("socket_comm::GetParameter - Units: %s\n", buffer);
        pList[i].units = std::string(buffer);

        memset(buffer, 0, 256);
        ReadMessage(socketFD, buffer);
        LOG("socket_comm::GetParameter - Min: %s\n", buffer);
        pList[i].min = atof(buffer);
    
        memset(buffer, 0, 256);
        ReadMessage(socketFD, buffer);
        LOG("socket_comm::GetParameter - Max: %s\n", buffer);
        pList[i].max = atof(buffer);
    
        memset(buffer, 0, 256);
        ReadMessage(socketFD, buffer);
        LOG("socket_comm::GetParameter - Step: %s\n", buffer);
        pList[i].step = atof(buffer);
    
        memset(buffer, 0, 256);
        ReadMessage(socketFD, buffer);
        LOG("socket_comm::GetParameter - Value: %s\n", buffer);
        pList[i].value = atof(buffer);
    }

    return 1;
}


// TODO if we are just returing fail/success here, then why not return a bool
// instead of an entire 32 bit integer?  Seems wasteful.
int32_t 
GetRequest(int32_t socketFD, struct Parameter pList[], struct CE_Info *ce_info)
{
    char buffer[256];
    memset(buffer, 0, 256);
   
    ReadMessage(socketFD, buffer);

    if(strcmp(buffer, "val") != 0) {
        LOG("socket_comm::GetRequest - Unexpected control data received.\n\n");
        return 0;
    }

    LOG("socket_comm::GetRequest - Getting parameters.\n\n");
    GetParameter(socketFD, pList, ce_info);

    return 1;
}