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The C based gRPC (C++, Python, Ruby, Objective-C, PHP, C#)
https://grpc.io/
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142 lines
3.9 KiB
142 lines
3.9 KiB
/* This is a simple TCP client that connects to port 1234 and prints a list |
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* of files in a given directory. |
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* |
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* It directly deserializes and serializes messages from network, minimizing |
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* memory use. |
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* |
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* For flexibility, this example is implemented using posix api. |
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* In a real embedded system you would typically use some other kind of |
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* a communication and filesystem layer. |
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*/ |
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#include <sys/socket.h> |
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#include <sys/types.h> |
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#include <netinet/in.h> |
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#include <unistd.h> |
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#include <dirent.h> |
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#include <stdio.h> |
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#include <string.h> |
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#include <pb_encode.h> |
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#include <pb_decode.h> |
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#include "fileproto.pb.h" |
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#include "common.h" |
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/* This callback function will be called once for each filename received |
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* from the server. The filenames will be printed out immediately, so that |
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* no memory has to be allocated for them. |
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*/ |
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bool printfile_callback(pb_istream_t *stream, const pb_field_t *field, void **arg) |
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{ |
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FileInfo fileinfo = {}; |
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if (!pb_decode(stream, FileInfo_fields, &fileinfo)) |
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return false; |
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printf("%-10lld %s\n", (long long)fileinfo.inode, fileinfo.name); |
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return true; |
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} |
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/* This function sends a request to socket 'fd' to list the files in |
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* directory given in 'path'. The results received from server will |
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* be printed to stdout. |
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*/ |
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bool listdir(int fd, char *path) |
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{ |
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/* Construct and send the request to server */ |
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{ |
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ListFilesRequest request = {}; |
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pb_ostream_t output = pb_ostream_from_socket(fd); |
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uint8_t zero = 0; |
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/* In our protocol, path is optional. If it is not given, |
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* the server will list the root directory. */ |
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if (path == NULL) |
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{ |
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request.has_path = false; |
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} |
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else |
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{ |
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request.has_path = true; |
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if (strlen(path) + 1 > sizeof(request.path)) |
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{ |
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fprintf(stderr, "Too long path.\n"); |
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return false; |
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} |
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strcpy(request.path, path); |
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} |
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/* Encode the request. It is written to the socket immediately |
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* through our custom stream. */ |
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if (!pb_encode(&output, ListFilesRequest_fields, &request)) |
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{ |
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fprintf(stderr, "Encoding failed: %s\n", PB_GET_ERROR(&output)); |
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return false; |
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} |
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/* We signal the end of request with a 0 tag. */ |
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pb_write(&output, &zero, 1); |
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} |
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/* Read back the response from server */ |
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{ |
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ListFilesResponse response = {}; |
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pb_istream_t input = pb_istream_from_socket(fd); |
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/* Give a pointer to our callback function, which will handle the |
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* filenames as they arrive. */ |
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response.file.funcs.decode = &printfile_callback; |
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if (!pb_decode(&input, ListFilesResponse_fields, &response)) |
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{ |
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fprintf(stderr, "Decode failed: %s\n", PB_GET_ERROR(&input)); |
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return false; |
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} |
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/* If the message from server decodes properly, but directory was |
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* not found on server side, we get path_error == true. */ |
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if (response.path_error) |
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{ |
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fprintf(stderr, "Server reported error.\n"); |
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return false; |
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} |
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} |
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return true; |
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} |
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int main(int argc, char **argv) |
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{ |
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int sockfd; |
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struct sockaddr_in servaddr; |
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char *path = NULL; |
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if (argc > 1) |
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path = argv[1]; |
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sockfd = socket(AF_INET, SOCK_STREAM, 0); |
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/* Connect to server running on localhost:1234 */ |
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memset(&servaddr, 0, sizeof(servaddr)); |
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servaddr.sin_family = AF_INET; |
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servaddr.sin_addr.s_addr = htonl(INADDR_LOOPBACK); |
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servaddr.sin_port = htons(1234); |
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if (connect(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr)) != 0) |
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{ |
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perror("connect"); |
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return 1; |
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} |
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/* Send the directory listing request */ |
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if (!listdir(sockfd, path)) |
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return 2; |
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/* Close connection */ |
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close(sockfd); |
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return 0; |
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}
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