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 uint8_t zero = 0;
53
54 /* In our protocol, path is optional. If it is not given,
55 * the server will list the root directory. */
56 if (path == NULL)
57 {
58 request.has_path = false;
59 }
60 else
61 {
62 request.has_path = true;
63 if (strlen(path) + 1 > sizeof(request.path))
64 {
65 fprintf(stderr, "Too long path.\n");
66 return false;
67 }
68
69 strcpy(request.path, path);
70 }
71
72 /* Encode the request. It is written to the socket immediately
73 * through our custom stream. */
74 if (!pb_encode(&output, ListFilesRequest_fields, &request))
75 {
76 fprintf(stderr, "Encoding failed: %s\n", PB_GET_ERROR(&output));
77 return false;
78 }
79
80 /* We signal the end of request with a 0 tag. */
81 pb_write(&output, &zero, 1);
82 }
83
84 /* Read back the response from server */
85 {
86 ListFilesResponse response = {};
87 pb_istream_t input = pb_istream_from_socket(fd);
88
89 /* Give a pointer to our callback function, which will handle the
90 * filenames as they arrive. */
91 response.file.funcs.decode = &printfile_callback;
92
93 if (!pb_decode(&input, ListFilesResponse_fields, &response))
94 {
95 fprintf(stderr, "Decode failed: %s\n", PB_GET_ERROR(&input));
96 return false;
97 }
98
99 /* If the message from server decodes properly, but directory was
100 * not found on server side, we get path_error == true. */
101 if (response.path_error)
102 {
103 fprintf(stderr, "Server reported error.\n");
104 return false;
105 }
106 }
107
108 return true;
109 }
110
main(int argc,char ** argv)111 int main(int argc, char **argv)
112 {
113 int sockfd;
114 struct sockaddr_in servaddr;
115 char *path = NULL;
116
117 if (argc > 1)
118 path = argv[1];
119
120 sockfd = socket(AF_INET, SOCK_STREAM, 0);
121
122 /* Connect to server running on localhost:1234 */
123 memset(&servaddr, 0, sizeof(servaddr));
124 servaddr.sin_family = AF_INET;
125 servaddr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
126 servaddr.sin_port = htons(1234);
127
128 if (connect(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr)) != 0)
129 {
130 perror("connect");
131 return 1;
132 }
133
134 /* Send the directory listing request */
135 if (!listdir(sockfd, path))
136 return 2;
137
138 /* Close connection */
139 close(sockfd);
140
141 return 0;
142 }
143