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POSimple http server in C, multiple process not work properly
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copied!<h2>Solved by adding fseek(file, 0, 0) once finished a repsonse.</h2> <p>I am programming a very simple http server, which will reply any GET request with a HTTP response. The response content will be passed to the program when it started, e.g. </p> <pre><code>$./server test1.html 999 </code></pre> <p>This command will open listen to 999 port, if got any GET request, the server will send "http headers" + "content of test1.html" to the requesting client.</p> <p>The fork() part doesn't work well, I can get the correct response for the first time, but after that, new clients won't receive anything from the server (cookies and cache are cleared).</p> <p>I debugged, the program would fprintf() the correct content, the problem is "client won't receive them". </p> <p>Below is my code, there is a function called get_mime_type(), you can ignore it and set mime to "text/html" or whatever you want.</p> <p>Any hints?</p> <p>BTW, I also want to avoid using multiple process to handle multiple connections, any idea on implementing a single-process, single-threaded http server?</p> <pre><code>#include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <errno.h> #include <string.h> #include <sys/types.h> #include <sys/socket.h> #include <sys/wait.h> #include <sys/stat.h> #include <netinet/in.h> #include <netdb.h> #include <arpa/inet.h> #include <signal.h> #include <dirent.h> #include <time.h> #include <unistd.h> #define BACKLOG 1024 #define RFC1123FMT "%a, %d %b %Y %H:%M:%S GMT" #define DEBUG 1 /** * Get the mime type of a file * * Pre-Condition: 1. mime-types.tsv is in current directory, and it is correct * 2. file exists and all right */ char *get_mime_type(char *filename) { // Get extension char *ext; // file extension if ((ext = strrchr(filename, '.')) == NULL) { fprintf(stderr, "Error: Cannot get the extension of \"%s\".\n", filename); exit(1); } ext += sizeof(char); // get rid of the `.' // Read in mime-types.tsv and try to get the mime-type regarding to current file's extension // No detailed error-checking according to pre-condition FILE *mime_file; mime_file = fopen("mime-types.tsv", "r"); int BUF_MAX = 1024; char *buffer = (char *)malloc(sizeof(char) * BUF_MAX); char *mime; fgets(buffer, BUF_MAX, mime_file); int linum = atoi(buffer); while (linum-- > 0) { fgets(buffer, BUF_MAX, mime_file); if ((strncasecmp(buffer, ext, strlen(ext))) == 0) { buffer[strlen(buffer) - 1] = '\0'; mime = buffer; while (*mime != ' ') { mime += sizeof(char); } mime += sizeof(char); free(buffer); // TODO: is this all right? fclose(mime_file); return mime; } } free(buffer); fclose(mime_file); return NULL; } void sigchld_handler(int s) { while(waitpid(-1, NULL, WNOHANG) > 0); } /** * Get sockaddr, IPv4 or IPv6: */ void *get_in_addr(struct sockaddr *sig_action) { if (sig_action->sa_family == AF_INET) { return &(((struct sockaddr_in*)sig_action)->sin_addr); } return &(((struct sockaddr_in6*)sig_action)->sin6_addr); } /** * Open a socket and listen to it, send information once got requests */ int run_server(char *filename, char *port) { // open file and get its information FILE *file; struct stat statbuf; if (stat(filename, &statbuf) < 0) { fprintf(stderr, "Error: Unable to open \"%s\".\n", filename); exit(1); } if (S_ISDIR(statbuf.st_mode)) { fprintf(stderr, "Error: %s is a directory, expected a file.\n", filename); exit(1); } if ((file = fopen(filename, "r")) == NULL) { fprintf(stderr, "Error: Unable to open \"%s\".\n", filename); exit(1); } char *mime = get_mime_type(filename); if (mime == NULL) { fprintf(stderr, "Error: the type of \"%s\" cannot be recognised.\n", filename); exit(1); } int file_len = S_ISREG(statbuf.st_mode) ? statbuf.st_size : -1; time_t mtime = statbuf.st_mtime; // last modified time, used in header // init sock int server_fd, client_fd; struct addrinfo hints, *server_info, *p_server_info; struct sockaddr_storage client_addr; socklen_t sock_in_size; struct sigaction sig_action; int yes = 1; char client_ip[INET6_ADDRSTRLEN]; int return_value; // store return value of getaddrinfo memset(&hints, 0, sizeof(hints)); hints.ai_family = AF_UNSPEC; hints.ai_socktype = SOCK_STREAM; hints.ai_flags = AI_PASSIVE; if ((return_value = getaddrinfo(NULL, port, &hints, &server_info)) != 0) { fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(return_value)); return 1; } // TODO ? free hints? free p_server_info // bind for (p_server_info = server_info; p_server_info != NULL; p_server_info = p_server_info->ai_next) { if ((server_fd = socket(p_server_info->ai_family, p_server_info->ai_socktype, p_server_info->ai_protocol)) == -1) { perror("server: socket"); continue; } if (setsockopt(server_fd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(int)) == -1) { perror("setsockopt"); exit(1); } if (bind(server_fd, p_server_info->ai_addr, p_server_info->ai_addrlen) == -1) { close(server_fd); perror("server: bind"); continue; } break; } if (p_server_info == NULL) { // not bind fprintf(stderr, "server: failed to bind\n"); return 2; } freeaddrinfo(server_info); // listen if (listen(server_fd, BACKLOG) == -1) { perror("listen"); exit(1); } // reap dead processes sig_action.sa_handler = sigchld_handler; sigemptyset(&sig_action.sa_mask); sig_action.sa_flags = SA_RESTART; if (sigaction(SIGCHLD, &sig_action, NULL) == -1) { perror("sigaction"); exit(1); } printf("server: waiting for connections...\n"); while (1) { sock_in_size = sizeof(client_addr); client_fd = accept(server_fd, (struct sockaddr *) &client_addr, &sock_in_size); if (client_fd == -1) { perror("accept"); continue; } inet_ntop(client_addr.ss_family, get_in_addr((struct sockaddr *)&client_addr), client_ip, sizeof(client_ip)); printf("server: got connection from %s\n", client_ip); if (!fork()) { // child process close(server_fd); FILE* response = fdopen(client_fd, "a+"); // response file // response header time_t now; char timebuf[128]; now = time(NULL); strftime(timebuf, sizeof(timebuf), RFC1123FMT, gmtime(&now)); fprintf(response, "HTTP/1.1 200 OK\r\n"); fprintf(response, "Server: server\r\n"); fprintf(response, "Date: %s\r\n", timebuf); strftime(timebuf, sizeof(timebuf), RFC1123FMT, gmtime(&mtime)); fprintf(response, "Last-Modified: %s\r\n", timebuf); fprintf(response, "Content-Type: %s\r\n", mime); fprintf(response, "Content-Length: %d\r\n", file_len); fprintf(response, "Connection: close\r\n"); fprintf(response, "\r\n"); // response content char buf[1024]; int n; while ((n = fread(buf, 1, sizeof(buf), file)) > 0) { fwrite(buf, 1, n, response); } fclose(response); fclose(file); close(client_fd); exit(0); } } fclose(file); close(server_fd); return 0; } int main(int argc, char *argv[]) { if (argc != 3) { fprintf(stderr, "Usage: $server filename port\n"); exit(1); } char *filename = argv[1]; char *port = argv[2]; return run_server(filename, port); } </code></pre>

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