1 /* This is a simple TCP client that connects to port 1234 and prints a list
2 * of files in a given directory.
3 *
4 * It directly deserializes and serializes messages from network, minimizing
5 * memory use.
6 *
7 * For flexibility, this example is implemented using posix api.
8 * In a real embedded system you would typically use some other kind of
9 * a communication and filesystem layer.
10 */
11
12 #include <sys/socket.h>
13 #include <sys/types.h>
14 #include <netinet/in.h>
15 #include <unistd.h>
16 #include <dirent.h>
17 #include <stdio.h>
18 #include <string.h>
19
20 #include <pb_encode.h>
21 #include <pb_decode.h>
22
23 #include "fileproto.pb.h"
24 #include "common.h"
25
26 /* This callback function will be called once for each filename received
27 * from the server. The filenames will be printed out immediately, so that
28 * no memory has to be allocated for them.
29 */
printfile_callback(pb_istream_t * stream,const pb_field_t * field,void ** arg)30 bool printfile_callback(pb_istream_t *stream, const pb_field_t *field, void **arg)
31 {
32 FileInfo fileinfo = {};
33
34 if (!pb_decode(stream, FileInfo_fields, &fileinfo))
35 return false;
36
37 printf("%-10lld %s\n", (long long)fileinfo.inode, fileinfo.name);
38
39 return true;
40 }
41
42 /* This function sends a request to socket 'fd' to list the files in
43 * directory given in 'path'. The results received from server will
44 * be printed to stdout.
45 */
listdir(int fd,char * path)46 bool listdir(int fd, char *path)
47 {
48 /* Construct and send the request to server */
49 {
50 ListFilesRequest request = {};
51 pb_ostream_t output = pb_ostream_from_socket(fd);
52
53 /* In our protocol, path is optional. If it is not given,
54 * the server will list the root directory. */
55 if (path == NULL)
56 {
57 request.has_path = false;
58 }
59 else
60 {
61 request.has_path = true;
62 if (strlen(path) + 1 > sizeof(request.path))
63 {
64 fprintf(stderr, "Too long path.\n");
65 return false;
66 }
67
68 strcpy(request.path, path);
69 }
70
71 /* Encode the request. It is written to the socket immediately
72 * through our custom stream. */
73 if (!pb_encode_delimited(&output, ListFilesRequest_fields, &request))
74 {
75 fprintf(stderr, "Encoding failed: %s\n", PB_GET_ERROR(&output));
76 return false;
77 }
78 }
79
80 /* Read back the response from server */
81 {
82 ListFilesResponse response = {};
83 pb_istream_t input = pb_istream_from_socket(fd);
84
85 /* Give a pointer to our callback function, which will handle the
86 * filenames as they arrive. */
87 response.file.funcs.decode = &printfile_callback;
88
89 if (!pb_decode_delimited(&input, ListFilesResponse_fields, &response))
90 {
91 fprintf(stderr, "Decode failed: %s\n", PB_GET_ERROR(&input));
92 return false;
93 }
94
95 /* If the message from server decodes properly, but directory was
96 * not found on server side, we get path_error == true. */
97 if (response.path_error)
98 {
99 fprintf(stderr, "Server reported error.\n");
100 return false;
101 }
102 }
103
104 return true;
105 }
106
main(int argc,char ** argv)107 int main(int argc, char **argv)
108 {
109 int sockfd;
110 struct sockaddr_in servaddr;
111 char *path = NULL;
112
113 if (argc > 1)
114 path = argv[1];
115
116 sockfd = socket(AF_INET, SOCK_STREAM, 0);
117
118 /* Connect to server running on localhost:1234 */
119 memset(&servaddr, 0, sizeof(servaddr));
120 servaddr.sin_family = AF_INET;
121 servaddr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
122 servaddr.sin_port = htons(1234);
123
124 if (connect(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr)) != 0)
125 {
126 perror("connect");
127 return 1;
128 }
129
130 /* Send the directory listing request */
131 if (!listdir(sockfd, path))
132 return 2;
133
134 /* Close connection */
135 close(sockfd);
136
137 return 0;
138 }
139