#include "fileproto.pb.h"
#include "common.h"
+/* This callback function will be called once for each filename received
+ * from the server. The filenames will be printed out immediately, so that
+ * no memory has to be allocated for them.
+ */
bool printfile_callback(pb_istream_t *stream, const pb_field_t *field, void **arg)
{
- FileInfo fileinfo;
+ FileInfo fileinfo = {};
if (!pb_decode(stream, FileInfo_fields, &fileinfo))
return false;
return true;
}
+/* This function sends a request to socket 'fd' to list the files in
+ * directory given in 'path'. The results received from server will
+ * be printed to stdout.
+ */
bool listdir(int fd, char *path)
{
- ListFilesRequest request;
- ListFilesResponse response;
- pb_istream_t input = pb_istream_from_socket(fd);
- pb_ostream_t output = pb_ostream_from_socket(fd);
- uint8_t zero = 0;
-
- if (path == NULL)
- {
- request.has_path = false;
- }
- else
+ /* Construct and send the request to server */
{
- request.has_path = true;
- if (strlen(path) + 1 > sizeof(request.path))
+ ListFilesRequest request = {};
+ pb_ostream_t output = pb_ostream_from_socket(fd);
+ uint8_t zero = 0;
+
+ /* In our protocol, path is optional. If it is not given,
+ * the server will list the root directory. */
+ if (path == NULL)
+ {
+ request.has_path = false;
+ }
+ else
{
- fprintf(stderr, "Too long path.\n");
+ request.has_path = true;
+ if (strlen(path) + 1 > sizeof(request.path))
+ {
+ fprintf(stderr, "Too long path.\n");
+ return false;
+ }
+
+ strcpy(request.path, path);
+ }
+
+ /* Encode the request. It is written to the socket immediately
+ * through our custom stream. */
+ if (!pb_encode(&output, ListFilesRequest_fields, &request))
+ {
+ fprintf(stderr, "Encoding failed: %s\n", PB_GET_ERROR(&output));
return false;
}
- strcpy(request.path, path);
+ /* We signal the end of request with a 0 tag. */
+ pb_write(&output, &zero, 1);
}
- if (!pb_encode(&output, ListFilesRequest_fields, &request))
+ /* Read back the response from server */
{
- fprintf(stderr, "Encoding failed.\n");
- return false;
- }
-
- /* We signal the end of request with a 0 tag. */
- pb_write(&output, &zero, 1);
-
- response.file.funcs.decode = &printfile_callback;
-
- if (!pb_decode(&input, ListFilesResponse_fields, &response))
- {
- fprintf(stderr, "Decode failed: %s\n", PB_GET_ERROR(&input));
- return false;
- }
-
- if (response.path_error)
- {
- fprintf(stderr, "Server reported error.\n");
- return false;
+ ListFilesResponse response = {};
+ pb_istream_t input = pb_istream_from_socket(fd);
+
+ /* Give a pointer to our callback function, which will handle the
+ * filenames as they arrive. */
+ response.file.funcs.decode = &printfile_callback;
+
+ if (!pb_decode(&input, ListFilesResponse_fields, &response))
+ {
+ fprintf(stderr, "Decode failed: %s\n", PB_GET_ERROR(&input));
+ return false;
+ }
+
+ /* If the message from server decodes properly, but directory was
+ * not found on server side, we get path_error == true. */
+ if (response.path_error)
+ {
+ fprintf(stderr, "Server reported error.\n");
+ return false;
+ }
}
return true;
sockfd = socket(AF_INET, SOCK_STREAM, 0);
+ /* Connect to server running on localhost:1234 */
memset(&servaddr, 0, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
return 1;
}
+ /* Send the directory listing request */
if (!listdir(sockfd, path))
return 2;
+ /* Close connection */
close(sockfd);
return 0;
#include "fileproto.pb.h"
#include "common.h"
+/* This callback function will be called once during the encoding.
+ * It will write out any number of FileInfo entries, without consuming unnecessary memory.
+ * This is accomplished by fetching the filenames one at a time and encoding them
+ * immediately.
+ */
bool listdir_callback(pb_ostream_t *stream, const pb_field_t *field, void * const *arg)
{
DIR *dir = (DIR*) *arg;
struct dirent *file;
- FileInfo fileinfo;
+ FileInfo fileinfo = {};
while ((file = readdir(dir)) != NULL)
{
strncpy(fileinfo.name, file->d_name, sizeof(fileinfo.name));
fileinfo.name[sizeof(fileinfo.name) - 1] = '\0';
+ /* This encodes the header for the field, based on the constant info
+ * from pb_field_t. */
if (!pb_encode_tag_for_field(stream, field))
return false;
+ /* This encodes the data for the field, based on our FileInfo structure. */
if (!pb_encode_submessage(stream, FileInfo_fields, &fileinfo))
return false;
}
return true;
}
+/* Handle one arriving client connection.
+ * Clients are expected to send a ListFilesRequest, terminated by a '0'.
+ * Server will respond with a ListFilesResponse message.
+ */
void handle_connection(int connfd)
{
- ListFilesRequest request;
- ListFilesResponse response;
- pb_istream_t input = pb_istream_from_socket(connfd);
- pb_ostream_t output = pb_ostream_from_socket(connfd);
- DIR *directory;
+ DIR *directory = NULL;
- if (!pb_decode(&input, ListFilesRequest_fields, &request))
+ /* Decode the message from the client and open the requested directory. */
{
- printf("Decode failed: %s\n", PB_GET_ERROR(&input));
- return;
+ ListFilesRequest request = {};
+ pb_istream_t input = pb_istream_from_socket(connfd);
+
+ if (!pb_decode(&input, ListFilesRequest_fields, &request))
+ {
+ printf("Decode failed: %s\n", PB_GET_ERROR(&input));
+ return;
+ }
+
+ directory = opendir(request.path);
+ printf("Listing directory: %s\n", request.path);
}
- directory = opendir(request.path);
-
- printf("Listing directory: %s\n", request.path);
-
- if (directory == NULL)
+ /* List the files in the directory and transmit the response to client */
{
- perror("opendir");
+ ListFilesResponse response = {};
+ pb_ostream_t output = pb_ostream_from_socket(connfd);
- response.has_path_error = true;
- response.path_error = true;
- response.file.funcs.encode = NULL;
- }
- else
- {
- response.has_path_error = false;
- response.file.funcs.encode = &listdir_callback;
- response.file.arg = directory;
+ if (directory == NULL)
+ {
+ perror("opendir");
+
+ /* Directory was not found, transmit error status */
+ response.has_path_error = true;
+ response.path_error = true;
+ response.file.funcs.encode = NULL;
+ }
+ else
+ {
+ /* Directory was found, transmit filenames */
+ response.has_path_error = false;
+ response.file.funcs.encode = &listdir_callback;
+ response.file.arg = directory;
+ }
+
+ if (!pb_encode(&output, ListFilesResponse_fields, &response))
+ {
+ printf("Encoding failed: %s\n", PB_GET_ERROR(&output));
+ }
}
- if (!pb_encode(&output, ListFilesResponse_fields, &response))
- {
- printf("Encoding failed.\n");
- }
+ if (directory != NULL)
+ closedir(directory);
}
int main(int argc, char **argv)
struct sockaddr_in servaddr;
int reuse = 1;
+ /* Listen on localhost:1234 for TCP connections */
listenfd = socket(AF_INET, SOCK_STREAM, 0);
-
setsockopt(listenfd, SOL_SOCKET, SO_REUSEADDR, &reuse, sizeof(reuse));
memset(&servaddr, 0, sizeof(servaddr));
for(;;)
{
+ /* Wait for a client */
connfd = accept(listenfd, NULL, NULL);
if (connfd < 0)
close(connfd);
}
+
+ return 0;
}
Code Review / apps / agl-service-can-low-level.git / commitdiff