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client.c
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client.c
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#include "client.h"
int main(int argc, char *argv[]){
int sockfd;
struct addrinfo hints, *servinfo, *p;
int rv;
int numbytes;
char *fileName, *hostName;
char packet[MAXBUFLEN];
FILE *fr;
hostName = malloc(strlen(argv[1]));
strcpy(hostName, argv[1]);
fileName = malloc(100);
strcpy(fileName, getCommand());
if (argc != 2) {
fprintf(stderr,"usage: talker hostname message\n");
exit(1);
}
memset(&hints, 0, sizeof hints);
hints.ai_family = AF_UNSPEC;
hints.ai_socktype = SOCK_DGRAM;
if ((rv = getaddrinfo(hostName, SERVERPORT, &hints, &servinfo)) != 0) {
fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv));
return 1;
}
// loop through all the results and make a socket
for(p = servinfo; p != NULL; p = p->ai_next) {
if ((sockfd = socket(p->ai_family, p->ai_socktype,
p->ai_protocol)) == -1) {
perror("talker: socket");
continue;
}
break;
}
if (p == NULL) {
fprintf(stderr, "talker: failed to bind socket\n");
return 2;
}
if(requestFile(fileName, p, sockfd, hostName) == 1){
puts("File request successful! \nBegin receiving data.");
receiveFile(p, sockfd, fileName);
}
else{
puts("File does not exist.");
}
freeaddrinfo(servinfo);
close(sockfd);
free(fileName);
return 0;
}
void receiveFile(struct addrinfo *p, int sockfd, char *fileName){
int numBytes;
char incMessage[MAXBUFLEN];
char message [MESSAGELENGTH];
size_t len;
strsep(&fileName, ",");
//FILE *fr = fopen(&fileName[0], "w");
FILE *fr = fopen("test.txt", "w");
struct sockaddr_storage their_addr;
socklen_t addr_len;
addr_len = sizeof their_addr;
do{
memset(incMessage, 0, MAXBUFLEN);
memset(message, 0, MESSAGELENGTH);
puts("Waiting for file data...");
if ((numBytes = recvfrom(sockfd, incMessage, MAXBUFLEN , 0,
(struct sockaddr *)&their_addr, &addr_len)) == -1) {
perror("recvfrom");
puts("The packet appears to have been lost.");
}
len = strlen(incMessage);
puts("Data received! Saving to file...");
if(len > HEADERSIZE){
strncpy(message, incMessage + HEADERSIZE, strlen(incMessage) - HEADERSIZE);
//Do checksum stuff
//Do GBN stuff
//Do SeqNum stuff
printf("\nSeqNum: %c%c\n\n", incMessage[0], incMessage[1]);
char tempSeqNum[2];
tempSeqNum[0] = incMessage[0];
tempSeqNum[1] = incMessage[1];
int incSeqNum = atoi(tempSeqNum);
printf("IncSeqNum = %d\n", incSeqNum);
int expectedSeqNum = seqNum % MODULUS;
char acknak[1];
char seqNumOut[2];
char checksum[] = "11";
if (expectedSeqNum == incSeqNum)
{
acknak[0] = ACK;
sprintf(seqNumOut, "%ld", (expectedSeqNum+1)%MODULUS);
if ((expectedSeqNum+1)%MODULUS < 10)
{
seqNumOut[1] = seqNumOut[0];
seqNumOut[0] = '0';
}
printf("SeqNumOut = %s\n", seqNumOut);
seqNum++;
fprintf(fr, "%s", message);
}
else if (0) // If checksum fails
{
acknak[0] = NAK;
sprintf(seqNumOut, "%ld", expectedSeqNum);
if (expectedSeqNum < 10)
{
seqNumOut[1] = seqNumOut[0];
seqNumOut[0] = '0';
}
}
else
{
acknak[0] = ACK;
sprintf(seqNumOut, "%ld", expectedSeqNum);
if (expectedSeqNum < 10)
{
seqNumOut[1] = seqNumOut[0];
seqNumOut[0] = '0';
}
printf("SeqNumOutOops = %s\n", seqNumOut);
}
buildPacket(seqNumOut, checksum, acknak);
if ((numBytes = sendto(sockfd, currPacket, strlen(currPacket), 0,
(struct sockaddr *)&their_addr, addr_len)) == -1) {
perror("talker: sendto");
}
//if all success, print to file
//fprintf(fr, "%s", message);
}
}while(len > HEADERSIZE);
puts("Finished receiving file. Saving and closing.");
fclose(fr);
}
char *getMessage(char incMessage[MAXBUFLEN]){
char *message;
int i;
for(i = HEADERSIZE; i < MAXBUFLEN - 1;i++){
message[i - HEADERSIZE] = incMessage[i];
}
return message;
}
char * getCommand(){
char *fileName, *command, *returnMes;
puts("What do you want to do?");
fileName = malloc(50);
command = malloc(50);
scanf("%s", command);
while(strcmp(command, "GET") != 0){
puts("Command not support. ctrc-c to end or enter another command");
scanf("%s", command);
}
puts("What file would you like to get?");
scanf("%s", fileName);
puts("");
strcpy(returnMes, "GET,");
strcat(returnMes, fileName);
return returnMes;
}
int transfer(char packet[513], struct addrinfo *p, int sockfd, char *hostname){
return 0;
}
int requestFile(char *fileName, struct addrinfo *p, int sockfd, char *hostname){
char incMessage[MAXBUFLEN];
int numBytes, valid;
char packet[strlen(fileName) + 4];
valid = 0;
struct sockaddr_storage their_addr;
socklen_t addr_len;
//strcpy(packet, "GET,");
//strcat(packet, fileName);
strcpy(packet, fileName);
printf("File request sent...");
if ((numBytes = sendto(sockfd, packet, strlen(packet), 0,
p->ai_addr, p->ai_addrlen)) == -1) {
perror("talker: sendto");
exit(1);
}
puts("Waiting for confirmation...");
addr_len = sizeof their_addr;
if ((numBytes = recvfrom(sockfd, incMessage, MAXBUFLEN , 0,
(struct sockaddr *)&their_addr, &addr_len)) == -1) {
perror("recvfrom");
puts("The packet appears to have been lost.");
}
if(strcmp(incMessage, "invalid") == 0){
}
else{
valid = 1;
}
return valid;
}
void buildPacket(char *seqNum, char *checkSum, char *acknak)
{
//puts("\nZeroing out current packet before building.");
memset(currPacket, 0, sizeof(currPacket));
//puts("Copying sequence number into packet");
//printf("SeqNumOutBuild = %s\n", seqNum);
strcpy(currPacket, seqNum);
//puts("Concatenating Checksum into packet");
strcat(currPacket, checkSum);
//puts("Concatenating acknak into packet");
strcat(currPacket, acknak);
//printf("Message = %s\n", message);
//puts("Packet built and ready for transfer!\n");
}