aboutsummaryrefslogtreecommitdiff
path: root/pa1_file_transfer/uftp_server.c
blob: e170b3f119bb96af1dc8a3a85c4739939cee78f5 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
// File Transfer (Server)
// Jack Sangdahl
// 07 September 2024
#include <arpa/inet.h>
#include <dirent.h>
#include <fcntl.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <unistd.h>

#define DATA_SIZE 1024

int main(int argc, char **argv) {
  if (argc != 2) {
    fprintf(stderr, "usage: %s <port_num>\n", argv[0]);
    exit(EXIT_FAILURE);
  }
  int port = atoi(argv[1]), sock;
  if (port > 65535 || port < 5000) {
    fprintf(stderr, "%s: port must be in range 5000-65535\n", argv[0]);
    exit(EXIT_FAILURE);
  }
  if ((sock = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
    fprintf(stderr, "%s: error opening socket\n", argv[0]);
    exit(EXIT_FAILURE);
  }
  struct sockaddr_in server_addr, client_addr;
  memset(&server_addr, 0, sizeof(server_addr));
  memset(&client_addr, 0, sizeof(client_addr));
  server_addr.sin_family = AF_INET;
  server_addr.sin_addr.s_addr = INADDR_ANY;
  server_addr.sin_port = htons((short)port);
  if (bind(sock, (const struct sockaddr *)&server_addr, sizeof(server_addr)) <
      0) {
    fprintf(stderr, "%s: error binding socket to port\n", argv[0]);
    exit(EXIT_FAILURE);
  }
  printf("ready to receive client connections\n");
  socklen_t client_size = sizeof(client_addr);
  char data[DATA_SIZE], command[DATA_SIZE], filename[DATA_SIZE];
  while (1) {
    memset(data, 0, strlen(data));
    ssize_t n = recvfrom(sock, data, DATA_SIZE, 0,
                         (struct sockaddr *)&client_addr, &client_size);
    if (n < 0)
      fprintf(stderr, "%s: error receiving datagram from client\n", argv[0]);
    struct hostent *host_info =
        gethostbyaddr((const char *)&client_addr.sin_addr.s_addr,
                      sizeof(client_addr.sin_addr.s_addr), AF_INET);
    if (!host_info)
      fprintf(stderr, "%s: error determining host info\n", argv[0]);
    char *host_addr = inet_ntoa(client_addr.sin_addr);
    printf("%s: received datagram from %s (%s)\n", argv[0], host_info->h_name,
           host_addr);
    printf("received %d/%d bytes: %s\n", (int)strlen(data), (int)n, data);
    sscanf(data, "%s %s", command, filename);
    if (!strncmp(command, "get", 3)) {
      printf("sending file %s to client...\n", filename);
      int send_data, f = open(filename, O_RDONLY);
      if (f < 0) {
        send_data = -1;
        fprintf(stderr, "error: file %s does not exist in directory\n",
                filename);
      } else
        send_data = 1;
      if (sendto(sock, &send_data, sizeof(send_data), 0,
                 (struct sockaddr *)&client_addr, client_size) < 0) {
        fprintf(stderr, "%s: error sending status to client\n", argv[0]);
        if (f >= 0)
          close(f);
        continue;
      }
      if (f < 0)
        continue;
      off_t file_size = lseek(f, 0, SEEK_END);
      if (file_size < 0) {
        fprintf(stderr, "error: determine file size of file %s\n", filename);
        close(f);
        continue;
      }
      lseek(f, 0, SEEK_SET);
      sprintf(data, "%ld", file_size);
      if (sendto(sock, data, strlen(data), 0, (struct sockaddr *)&client_addr,
                 client_size) < 0) {
        fprintf(stderr, "%s: error sending file size to client\n", argv[0]);
        close(f);
        continue;
      }
      memset(data, 0, sizeof(data));
      ssize_t bytes_read;
      while ((bytes_read = read(f, data, sizeof(data)))) {
        if (sendto(sock, data, bytes_read, 0, (struct sockaddr *)&client_addr,
                   client_size) < 0) {
          fprintf(stderr, "%s: error sending data to client\n", argv[0]);
          break;
        }
        memset(data, 0, sizeof(data));
      }
      if (bytes_read < 0)
        fprintf(stderr, "%s: error reading from file %s\n", argv[0], filename);
      close(f);
    } else if (!strncmp(command, "put", 3)) {
      printf("receiving file %s from client...\n", filename);
      if (recvfrom(sock, data, DATA_SIZE, 0, (struct sockaddr *)&client_addr,
                   &client_size) < 0)
        fprintf(stderr, "%s: error receiving data from client\n", argv[0]);
      int file_size = atoi(data),
          f = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666);
      if (f < 0)
        fprintf(stderr, "%s: error opening file %s\n", argv[0], filename);
      int bytes_transferred = 0;
      ssize_t bytes_received;
      while (bytes_transferred < file_size) {
        memset(data, 0, sizeof(data));
        int transfer_size = (file_size - bytes_transferred < DATA_SIZE)
                                ? (file_size - bytes_transferred)
                                : DATA_SIZE;
        bytes_received =
            recvfrom(sock, data, transfer_size, 0,
                     (struct sockaddr *)&client_addr, &client_size);
        if (bytes_received < 0) {
          fprintf(stderr, "%s: error receiving data from client\n", argv[0]);
          close(f);
        }
        if (write(f, data, bytes_received) != bytes_received) {
          fprintf(stderr, "%s: error writing data to file %s\n", argv[0],
                  filename);
          close(f);
        }
        bytes_transferred += bytes_received;
        printf("received %d/%d bytes\n", bytes_transferred, file_size);
      }
      close(f);
      printf("file %s transferred successfully\n", filename);
    } else if (!strncmp(command, "delete", 6)) {
      int send_data, f = open(filename, O_RDWR);
      if (f < 0) {
        send_data = 1;
        if (sendto(sock, &send_data, sizeof(int), 0,
                   (struct sockaddr *)&client_addr, client_size) < 0)
          fprintf(stderr, "%s: error sending data to client\n", argv[0]);
      }
      close(f);
      if (remove(filename) < 0) {
        send_data = 2;
        fprintf(stderr, "%s: error removing file %s\n", argv[0], filename);
      } else
        send_data = 0;
      if (sendto(sock, &send_data, sizeof(int), 0,
                 (struct sockaddr *)&client_addr, client_size) < 0)
        fprintf(stderr, "%s: error sending data to client\n", argv[0]);
    } else if (!strncmp(command, "ls", 2)) {
      char send_data[DATA_SIZE] = {0};
      DIR *d = opendir(".");
      int data_len = 0;
      struct dirent *curr;
      while ((curr = readdir(d))) {
        int name_len = strlen(curr->d_name);
        memcpy(send_data + data_len, curr->d_name, name_len);
        data_len += name_len;
        send_data[data_len] = '\n';
        data_len++;
      }
      closedir(d);
      if (data_len)
        if (sendto(sock, send_data, strlen(send_data), 0,
                   (struct sockaddr *)&client_addr, client_size) < 0)
          fprintf(stderr, "%s: error sending data to client\n", argv[0]);
    } else if (!strncmp(command, "exit", 4))
      printf("received exit signal from client\n");
  }
  return EXIT_SUCCESS;
}