web-server-threadpool/server.c at main · demadabbagh/web-server-threadpool · GitHub

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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include <errno.h>
#include <sys/types.h>
#include <sys/socket.h>

#include <netinet/in.h>
#include <arpa/inet.h>

#include <time.h>
#include <sys/stat.h>
#include <dirent.h>
#include <fcntl.h>
#include <signal.h>

#include "threadpool.h"

#define RFC1123FMT "%a, %d %b %Y %H:%M:%S GMT"

/* ===================== Date helpers ===================== */

static void make_date_now(char out[128])
{
    time_t now = time(NULL);
    strftime(out, 128, RFC1123FMT, gmtime(&now));
}

static void make_date_from_time(time_t t, char out[128])
{
    strftime(out, 128, RFC1123FMT, gmtime(&t));
}

/* ===================== MIME types (given) ===================== */
static char *get_mime_type(char *name)
{
    char *ext = strrchr(name, '.');
    if (!ext) return NULL;
    if (strcmp(ext, ".html") == 0 || strcmp(ext, ".htm") == 0) return "text/html";
    if (strcmp(ext, ".jpg") == 0 || strcmp(ext, ".jpeg") == 0) return "image/jpeg";
    if (strcmp(ext, ".gif") == 0) return "image/gif";
    if (strcmp(ext, ".png") == 0) return "image/png";
    if (strcmp(ext, ".css") == 0) return "text/css";
    if (strcmp(ext, ".au") == 0) return "audio/basic";
    if (strcmp(ext, ".wav") == 0) return "audio/wav";
    if (strcmp(ext, ".avi") == 0) return "video/x-msvideo";
    if (strcmp(ext, ".mpeg") == 0 || strcmp(ext, ".mpg") == 0) return "video/mpeg";
    if (strcmp(ext, ".mp3") == 0) return "audio/mpeg";
    return NULL;
}

/* ===================== Exact HTML bodies ===================== */

static const char *BODY_400 =
"<HTML><HEAD><TITLE>400 Bad Request</TITLE></HEAD>\n"
"<BODY><H4>400 Bad request</H4>\n"
"Bad Request.\n"
"</BODY></HTML>";

static const char *BODY_403 =
"<HTML><HEAD><TITLE>403 Forbidden</TITLE></HEAD>\n"
"<BODY><H4>403 Forbidden</H4>\n"
"Access denied.\n"
"</BODY></HTML>";

static const char *BODY_404 =
"<HTML><HEAD><TITLE>404 Not Found</TITLE></HEAD>\n"
"<BODY><H4>404 Not Found</H4>\n"
"File not found.\n"
"</BODY></HTML>";

static const char *BODY_500 =
"<HTML><HEAD><TITLE>500 Internal Server Error</TITLE></HEAD>\n"
"<BODY><H4>500 Internal Server Error</H4>\n"
"Some server side error.\n"
"</BODY></HTML>\n\n";

static const char *BODY_501 =
"<HTML><HEAD><TITLE>501 Not supported</TITLE></HEAD>\n"
"<BODY><H4>501 Not supported</H4>\n"
"Method is not supported.\n"
"</BODY></HTML>";

static const char *BODY_302 =
"<HTML><HEAD><TITLE>302 Found</TITLE></HEAD>\n"
"<BODY><H4>302 Found</H4>\n"
"Directories must end with a slash.\n"
"</BODY></HTML>";

/* ===================== Response sender ===================== */

static void send_html_response(int fd,
                              int code,
                              const char *phrase,
                              const char *location_or_null,
                              const char *body)
{
    char date[128];
    make_date_now(date);

    long body_len = (long)strlen(body);

    char header[4096];
    if (location_or_null) {
        snprintf(header, sizeof(header),
                 "HTTP/1.0 %d %s\r\n"
                 "Server: webserver/1.0\r\n"
                 "Date: %s\r\n"
                 "Location: %s\r\n"
                 "Content-Type: text/html\r\n"
                 "Content-Length: %ld\r\n"
                 "Connection: close\r\n"
                 "\r\n",
                 code, phrase, date, location_or_null, body_len);
    } else {
        snprintf(header, sizeof(header),
                 "HTTP/1.0 %d %s\r\n"
                 "Server: webserver/1.0\r\n"
                 "Date: %s\r\n"
                 "Content-Type: text/html\r\n"
                 "Content-Length: %ld\r\n"
                 "Connection: close\r\n"
                 "\r\n",
                 code, phrase, date, body_len);
    }

    send(fd, header, strlen(header), MSG_NOSIGNAL);
    send(fd, body, (size_t)body_len, MSG_NOSIGNAL);
}

static void send_400(int fd) { send_html_response(fd, 400, "Bad Request", NULL, BODY_400); }
static void send_403(int fd) { send_html_response(fd, 403, "Forbidden", NULL, BODY_403); }
static void send_404(int fd) { send_html_response(fd, 404, "Not Found", NULL, BODY_404); }
static void send_500(int fd) { send_html_response(fd, 500, "Internal Server Error", NULL, BODY_500); }
static void send_501(int fd) { send_html_response(fd, 501, "Not supported", NULL, BODY_501); }

static void send_302(int fd, const char *location_path_with_slash)
{
    send_html_response(fd, 302, "Found", location_path_with_slash, BODY_302);
}

/* ===================== Permission checks using stat() ===================== */

/*
 * FIX 1: Use stat() st_mode bits to check permissions instead of access().
 * access() checks as the real UID/GID of the running process (the owner),
 * so a file with -rw------- owned by the server user would pass access(R_OK).
 * We need to check the OTHER bits (world-readable) to enforce proper access control.
 */
static int check_readable(struct stat *st)
{
    /* Check world-readable bit */
    return (st->st_mode & S_IROTH) != 0;
}

static int check_executable(struct stat *st)
{
    /* Check world-executable bit */
    return (st->st_mode & S_IXOTH) != 0;
}

static int parent_dirs_have_x(const char *path)
{
    char temp[4096];
    if (!path || path[0] == '\0') return 0;

    strncpy(temp, path, sizeof(temp) - 1);
    temp[sizeof(temp) - 1] = '\0';

    char build[4096] = "";
    char *saveptr = NULL;
    char *tok = strtok_r(temp, "/", &saveptr);

    while (tok) {
        char *next = strtok_r(NULL, "/", &saveptr);
        if (!next) break; /* tok is file name, stop at parents */

        if (build[0] == '\0')
            snprintf(build, sizeof(build), "%s", tok);
        else {
            if (strlen(build) + 1 < sizeof(build)) strcat(build, "/");
            if (strlen(build) + strlen(tok) < sizeof(build)) strcat(build, tok);
        }

        if (access(build, X_OK) != 0) return 0;

        tok = next;
    }

    return 1;
}

static int dir_can_list_and_enter(const char *dirpath)
{
    struct stat st;
    if (stat(dirpath, &st) < 0) return 0;
    /* Need read+execute (world bits) on directory to list */
    return ((st.st_mode & S_IROTH) && (st.st_mode & S_IXOTH));
}

/* ===================== 200 OK file sender ===================== */

static void send_file_200(int client_fd, const char *filepath, struct stat *st)
{
    int fd = open(filepath, O_RDONLY);
    if (fd < 0) {
        /* FIX: open() failed unexpectedly -> 500 Internal Server Error */
        send_500(client_fd);
        return;
    }

    char date[128], lastmod[128];
    make_date_now(date);
    make_date_from_time(st->st_mtime, lastmod);

    char *mime = get_mime_type((char *)filepath);

    char header[4096];
    if (mime) {
        snprintf(header, sizeof(header),
                 "HTTP/1.0 200 OK\r\n"
                 "Server: webserver/1.0\r\n"
                 "Date: %s\r\n"
                 "Content-Type: %s\r\n"
                 "Content-Length: %ld\r\n"
                 "Last-Modified: %s\r\n"
                 "Connection: close\r\n"
                 "\r\n",
                 date, mime, (long)st->st_size, lastmod);
    } else {
        snprintf(header, sizeof(header),
                 "HTTP/1.0 200 OK\r\n"
                 "Server: webserver/1.0\r\n"
                 "Date: %s\r\n"
                 "Content-Length: %ld\r\n"
                 "Last-Modified: %s\r\n"
                 "Connection: close\r\n"
                 "\r\n",
                 date, (long)st->st_size, lastmod);
    }

    send(client_fd, header, strlen(header), MSG_NOSIGNAL);

    char buf[4096];
    int r;
    while ((r = read(fd, buf, sizeof(buf))) > 0) {
        if (send(client_fd, buf, r, MSG_NOSIGNAL) < 0) break;
    }

    close(fd);
}

/* ===================== Directory listing ===================== */

static void append_str(char *dst, size_t dstsz, const char *src)
{
    size_t dlen = strlen(dst);
    size_t slen = strlen(src);
    if (dlen + slen + 1 >= dstsz) return;
    memcpy(dst + dlen, src, slen);
    dst[dlen + slen] = '\0';
}

static void send_dir_listing_200(int client_fd, const char *fs_dirpath, const char *req_path_with_slash)
{
    DIR *dir = opendir(fs_dirpath);
    if (!dir) {
        send_403(client_fd);
        return;
    }

    struct stat dst;
    if (stat(fs_dirpath, &dst) < 0) {
        closedir(dir);
        send_403(client_fd);
        return;
    }

    char lastmod_dir[128];
    make_date_from_time(dst.st_mtime, lastmod_dir);

    char body[65536];
    body[0] = '\0';

    append_str(body, sizeof(body),
               "<HTML>\n"
               "<HEAD><TITLE>Index of ");
    append_str(body, sizeof(body), req_path_with_slash);
    append_str(body, sizeof(body),
               "</TITLE></HEAD>\n"
               "\r<BODY>\n"
               "<H4>Index of ");
    append_str(body, sizeof(body), req_path_with_slash);
    append_str(body, sizeof(body),
               "</H4>\n"
               "\r<table CELLSPACING=8>\n"
               "<tr><th>Name</th><th>Last Modified</th><th>Size</th></tr>\n"
               "\r\r");

    struct dirent *ent;
    while ((ent = readdir(dir)) != NULL) {
        if (strcmp(ent->d_name, ".") == 0 || strcmp(ent->d_name, "..") == 0)
            continue;

        char child_fs[4096];
        if (strcmp(fs_dirpath, ".") == 0) {
            snprintf(child_fs, sizeof(child_fs), "%s", ent->d_name);
        } else {
            snprintf(child_fs, sizeof(child_fs), "%s%s", fs_dirpath, ent->d_name);
        }

        struct stat st;
        if (stat(child_fs, &st) < 0) continue;

        char modt[128];
        make_date_from_time(st.st_mtime, modt);

        char sizebuf[64] = "";
        if (S_ISREG(st.st_mode)) {
            snprintf(sizebuf, sizeof(sizebuf), "%ld", (long)st.st_size);
        } else {
            sizebuf[0] = '\0';
        }

        append_str(body, sizeof(body), "<tr>\r<td><A HREF=\"");
        append_str(body, sizeof(body), ent->d_name);
        append_str(body, sizeof(body), "\">");
        append_str(body, sizeof(body), ent->d_name);
        append_str(body, sizeof(body), "</A></td><td>");
        append_str(body, sizeof(body), modt);
        append_str(body, sizeof(body), "</td>\r<td>");
        append_str(body, sizeof(body), sizebuf);
        append_str(body, sizeof(body), "</td>\r</tr>\r\n");
    }

    closedir(dir);

    append_str(body, sizeof(body),
               "</table>\r\n"
               "<HR>\r\n"
               "<ADDRESS>webserver/1.0</ADDRESS>\r\n"
               "</BODY></HTML>\r\n");

    long body_len = (long)strlen(body);

    char date[128];
    make_date_now(date);

    char header[4096];
    snprintf(header, sizeof(header),
             "HTTP/1.0 200 OK\r\n"
             "Server: webserver/1.0\r\n"
             "Date: %s\r\n"
             "Content-Type: text/html\r\n"
             "Content-Length: %ld\r\n"
             "Last-Modified: %s\r\n"
             "Connection: close\r\n"
             "\r\n",
             date, body_len, lastmod_dir);

    send(client_fd, header, strlen(header), MSG_NOSIGNAL);
    send(client_fd, body, (size_t)body_len, MSG_NOSIGNAL);
}

/* ===================== Request handler ===================== */

static void read_first_line(int fd, char out[4000])
{
    int i = 0;
    int bytes;

    while (i < 3999) {
        bytes = recv(fd, &out[i], 1, 0);
        if (bytes <= 0) break;

        if (i > 0 && out[i] == '\n' && out[i - 1] == '\r') break;
        i++;
    }
    out[i] = '\0';
}

void handle_request(int client_fd)
{
    char line[4000];
    read_first_line(client_fd, line);

    /* FIX 3: If client disconnected (empty line), send 500 and return */
    if (line[0] == '\0') {
        send_500(client_fd);
        close(client_fd);
        return;
    }

    char *method = strtok(line, " ");
    char *path   = strtok(NULL, " ");
    char *proto  = strtok(NULL, " \r\n");

    if (!method || !path || !proto || strtok(NULL, " ") != NULL) {
        send_400(client_fd);
        close(client_fd);
        return;
    }

    if (strcmp(proto, "HTTP/1.0") != 0 && strcmp(proto, "HTTP/1.1") != 0) {
        send_400(client_fd);
        close(client_fd);
        return;
    }

    if (strcmp(method, "GET") != 0) {
        send_501(client_fd);
        close(client_fd);
        return;
    }

    char req_path[4000];
    strncpy(req_path, path, sizeof(req_path) - 1);
    req_path[sizeof(req_path) - 1] = '\0';

    const char *p = path;
    if (p[0] == '/') p++;

    char fs_path[4096];

    if (p[0] == '\0') {
        strcpy(fs_path, ".");
    } else {
        snprintf(fs_path, sizeof(fs_path), "%s", p);
    }

    struct stat st;
    if (stat(fs_path, &st) < 0) {
        send_404(client_fd);
        close(client_fd);
        return;
    }

    if (S_ISDIR(st.st_mode)) {
        int req_len = (int)strlen(req_path);

        /* FIX 4: Check permissions BEFORE doing 302 redirect */
        if (!dir_can_list_and_enter(fs_path)) {
            send_403(client_fd);
            close(client_fd);
            return;
        }

        if (req_len == 0 || req_path[req_len - 1] != '/') {
            char location[4096];
            snprintf(location, sizeof(location), "%s/", req_path);
            send_302(client_fd, location);
            close(client_fd);
            return;
        }

        if (strcmp(fs_path, ".") != 0 && !parent_dirs_have_x(fs_path)) {
            send_403(client_fd);
            close(client_fd);
            return;
        }

        /* build index path safely */
        char index_path[4096];
        int need = snprintf(index_path, sizeof(index_path),
                            (fs_path[strlen(fs_path) - 1] == '/') ? "%sindex.html" : "%s/index.html",
                            fs_path);
        if (need < 0 || need >= (int)sizeof(index_path)) {
            send_403(client_fd);
            close(client_fd);
            return;
        }

        struct stat ist;
        if (stat(index_path, &ist) == 0) {
            /* FIX 1: use stat st_mode bits instead of access() */
            if (!S_ISREG(ist.st_mode) || !check_readable(&ist) || !parent_dirs_have_x(index_path)) {
                send_403(client_fd);
                close(client_fd);
                return;
            }
            send_file_200(client_fd, index_path, &ist);
            close(client_fd);
            return;
        }

        send_dir_listing_200(client_fd, fs_path, req_path);
        close(client_fd);
        return;
    }

    /* file - FIX 1: use stat st_mode bits instead of access() */
    if (!S_ISREG(st.st_mode) || !check_readable(&st) || !parent_dirs_have_x(fs_path)) {
        send_403(client_fd);
        close(client_fd);
        return;
    }

    send_file_200(client_fd, fs_path, &st);
    close(client_fd);
}

/* ===================== Threadpool wrapper ===================== */
static int handle_request_job(void *arg)
{
    int client_fd = *(int *)arg;
    free(arg);
    handle_request(client_fd);
    return 0;
}

/* ===================== main ===================== */

int main(int argc, char *argv[])
{
    /* FIX 3: Ignore SIGPIPE so server doesn't crash when client disconnects */
    signal(SIGPIPE, SIG_IGN);

    if (argc != 5) {
        fprintf(stderr,
                "Usage: server <port> <pool-size> <max-queue-size> <max-number-of-requests>\n");
        exit(1);
    }

    int port      = atoi(argv[1]);
    int pool_size = atoi(argv[2]);
    int max_q     = atoi(argv[3]);
    int max_req   = atoi(argv[4]);

    threadpool *pool = create_threadpool(pool_size, max_q);
    if (!pool) {
        fprintf(stderr, "Failed to create threadpool\n");
        exit(1);
    }

    int listen_fd = socket(AF_INET, SOCK_STREAM, 0);
    if (listen_fd < 0) {
        perror("socket");
        exit(1);
    }

    int opt = 1;
    setsockopt(listen_fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));

    struct sockaddr_in srv;
    memset(&srv, 0, sizeof(srv));
    srv.sin_family = AF_INET;
    srv.sin_port = htons((unsigned short)port);
    srv.sin_addr.s_addr = htonl(INADDR_ANY);

    if (bind(listen_fd, (struct sockaddr *)&srv, sizeof(srv)) < 0) {
        perror("bind");
        close(listen_fd);
        exit(1);
    }

    if (listen(listen_fd, 1024) < 0) {
        perror("listen");
        close(listen_fd);
        exit(1);
    }

    for (int i = 0; i < max_req; i++) {
        int client_fd = accept(listen_fd, NULL, NULL);
        if (client_fd < 0) {
            perror("accept");
            close(listen_fd);
            destroy_threadpool(pool);
            exit(1);
        }

        int *pfd = (int *)malloc(sizeof(int));
        if (!pfd) {
            send_500(client_fd);
            close(client_fd);
            continue;
        }

        *pfd = client_fd;
        dispatch(pool, handle_request_job, pfd);
    }

    close(listen_fd);
    destroy_threadpool(pool);
    return 0;
}