1 /* This is a simple TCP server that listens on port 1234 and provides lists
2 * of files to clients, using a protocol defined in file_server.proto.
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 during the encoding.
27 * It will write out any number of FileInfo entries, without consuming unnecessary memory.
28 * This is accomplished by fetching the filenames one at a time and encoding them
29 * immediately.
30 */
ListFilesResponse_callback(pb_istream_t * istream,pb_ostream_t * ostream,const pb_field_iter_t * field)31 bool ListFilesResponse_callback(pb_istream_t *istream, pb_ostream_t *ostream, const pb_field_iter_t *field)
32 {
33 PB_UNUSED(istream);
34 if (ostream != NULL && field->tag == ListFilesResponse_file_tag)
35 {
36 DIR *dir = *(DIR**)field->pData;
37 struct dirent *file;
38 FileInfo fileinfo = {};
39
40 while ((file = readdir(dir)) != NULL)
41 {
42 fileinfo.inode = file->d_ino;
43 strncpy(fileinfo.name, file->d_name, sizeof(fileinfo.name));
44 fileinfo.name[sizeof(fileinfo.name) - 1] = '\0';
45
46 /* This encodes the header for the field, based on the constant info
47 * from pb_field_t. */
48 if (!pb_encode_tag_for_field(ostream, field))
49 return false;
50
51 /* This encodes the data for the field, based on our FileInfo structure. */
52 if (!pb_encode_submessage(ostream, FileInfo_fields, &fileinfo))
53 return false;
54 }
55
56 /* Because the main program uses pb_encode_delimited(), this callback will be
57 * called twice. Rewind the directory for the next call. */
58 rewinddir(dir);
59 }
60
61 return true;
62 }
63
64 /* Handle one arriving client connection.
65 * Clients are expected to send a ListFilesRequest, terminated by a '0'.
66 * Server will respond with a ListFilesResponse message.
67 */
handle_connection(int connfd)68 void handle_connection(int connfd)
69 {
70 DIR *directory = NULL;
71
72 /* Decode the message from the client and open the requested directory. */
73 {
74 ListFilesRequest request = {};
75 pb_istream_t input = pb_istream_from_socket(connfd);
76
77 if (!pb_decode_delimited(&input, ListFilesRequest_fields, &request))
78 {
79 printf("Decode failed: %s\n", PB_GET_ERROR(&input));
80 return;
81 }
82
83 directory = opendir(request.path);
84 printf("Listing directory: %s\n", request.path);
85 }
86
87 /* List the files in the directory and transmit the response to client */
88 {
89 ListFilesResponse response = {};
90 pb_ostream_t output = pb_ostream_from_socket(connfd);
91
92 if (directory == NULL)
93 {
94 perror("opendir");
95
96 /* Directory was not found, transmit error status */
97 response.has_path_error = true;
98 response.path_error = true;
99 }
100 else
101 {
102 /* Directory was found, transmit filenames */
103 response.has_path_error = false;
104 response.file = directory;
105 }
106
107 if (!pb_encode_delimited(&output, ListFilesResponse_fields, &response))
108 {
109 printf("Encoding failed: %s\n", PB_GET_ERROR(&output));
110 }
111 }
112
113 if (directory != NULL)
114 closedir(directory);
115 }
116
main(int argc,char ** argv)117 int main(int argc, char **argv)
118 {
119 int listenfd, connfd;
120 struct sockaddr_in servaddr;
121 int reuse = 1;
122
123 /* Listen on localhost:1234 for TCP connections */
124 listenfd = socket(AF_INET, SOCK_STREAM, 0);
125 setsockopt(listenfd, SOL_SOCKET, SO_REUSEADDR, &reuse, sizeof(reuse));
126
127 memset(&servaddr, 0, sizeof(servaddr));
128 servaddr.sin_family = AF_INET;
129 servaddr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
130 servaddr.sin_port = htons(1234);
131 if (bind(listenfd, (struct sockaddr*)&servaddr, sizeof(servaddr)) != 0)
132 {
133 perror("bind");
134 return 1;
135 }
136
137 if (listen(listenfd, 5) != 0)
138 {
139 perror("listen");
140 return 1;
141 }
142
143 for(;;)
144 {
145 /* Wait for a client */
146 connfd = accept(listenfd, NULL, NULL);
147
148 if (connfd < 0)
149 {
150 perror("accept");
151 return 1;
152 }
153
154 printf("Got connection.\n");
155
156 handle_connection(connfd);
157
158 printf("Closing connection.\n");
159
160 close(connfd);
161 }
162
163 return 0;
164 }
165
