httpsrv.c

/*
 * httpsrv.c - minimal HTTP Server
 * 
 * Copyright (C) 2026 Raphael Hoefler
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see <https://www.gnu.org/licenses/>.
 */

#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <sys/stat.h>
#include <fcntl.h>

#define BUF_SIZE 4096

// ---- Content-Type erkennen nach Dateiendung ----
const char* get_content_type(const char *path) {
    const char *dot = strrchr(path, '.');
    if (!dot) return "application/octet-stream";

    if (strcmp(dot, ".html") == 0) return "text/html";
    if (strcmp(dot, ".htm") == 0) return "text/html";
    if (strcmp(dot, ".txt") == 0) return "text/plain";
    if (strcmp(dot, ".css") == 0) return "text/css";
    if (strcmp(dot, ".js") == 0) return "application/javascript";
    if (strcmp(dot, ".png") == 0) return "image/png";
    if (strcmp(dot, ".jpg") == 0) return "image/jpeg";
    if (strcmp(dot, ".jpeg") == 0) return "image/jpeg";
    if (strcmp(dot, ".gif") == 0) return "image/gif";
    if (strcmp(dot, ".ico") == 0) return "image/x-icon";
    return "application/octet-stream";
}

int main(int argc, char *argv[]) {
    int server_fd, client_fd;
    struct sockaddr_in address;
    int opt = 1;
    socklen_t addrlen = sizeof(address);

    char httproot[1024] = ".";
    int port = 8090;

    // ---- Kommandozeilenargumente ----
    int optch;
    while ((optch = getopt(argc, argv, "r:p:")) != -1) {
        switch (optch) {
            case 'r': strncpy(httproot, optarg, sizeof(httproot)-1); break;
            case 'p': port = atoi(optarg); break;
            default:
                fprintf(stderr, "Usage: %s [-r httproot] [-p port]\n", argv[0]);
                exit(1);
        }
    }

    printf("HTTP Root: %s\n", httproot);
    printf("Port: %d\n", port);

    // ---- Socket setup ----
    server_fd = socket(AF_INET, SOCK_STREAM, 0);
    if (server_fd < 0) { perror("socket"); exit(1); }

    setsockopt(server_fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));
    setsockopt(server_fd, SOL_SOCKET, SO_REUSEPORT, &opt, sizeof(opt));

    address.sin_family = AF_INET;
    address.sin_addr.s_addr = INADDR_ANY;
    address.sin_port = htons(port);

    if (bind(server_fd, (struct sockaddr*)&address, sizeof(address)) < 0) {
        perror("bind"); exit(1);
    }

    if (listen(server_fd, 10) < 0) {
        perror("listen"); exit(1);
    }

    printf("Listening on port %d...\n", port);

    // ---- Server loop ----
    while (1) {
        char buffer[BUF_SIZE];
        int total = 0;

        client_fd = accept(server_fd, (struct sockaddr*)&address, &addrlen);
        if (client_fd < 0) { perror("accept"); continue; }

        // ---- HTTP Header lesen ----
        while (1) {
            int n = read(client_fd, buffer + total, sizeof(buffer) - total - 1);
            if (n <= 0) break;

            total += n;
            buffer[total] = 0;

            if (strstr(buffer, "\r\n\r\n")) break;  // Ende Header
        }

        // ---- Erste Zeile parsen ----
        char *saveptr;
        char *line = strtok_r(buffer, "\r\n", &saveptr);

        char method[16];
        char path[1024] = "/";

        if (line) {
            sscanf(line, "%15s %1023s", method, path);
        }

        printf("Requested path: %s\n", path);

        // ---- User-Agent extrahieren ----
        char useragent[1024] = "(none)";
        line = strtok_r(NULL, "\r\n", &saveptr);
        while (line) {
            if (strncasecmp(line, "User-Agent:", 11) == 0) {
                char *ua = line + 11;
                while (*ua == ' ') ua++;
                strncpy(useragent, ua, sizeof(useragent) - 1);
                useragent[sizeof(useragent) - 1] = 0;
                break;
            }
            line = strtok_r(NULL, "\r\n", &saveptr);
        }

        char response[BUF_SIZE];

        // ---- /useragent Sonderfall ----
        if (strcmp(path, "/useragent") == 0) {
            snprintf(response, sizeof(response),
                     "HTTP/1.1 200 OK\r\n"
                     "Server: httpsrv\r\n"
                     "Content-Type: text/plain\r\n"
                     "Content-Length: %zu\r\n"
                     "Connection: close\r\n"
                     "\r\n"
                     "%s",
                     strlen(useragent), useragent);
            send(client_fd, response, strlen(response), 0);
        } else {
            // ---- Datei aus HTTP-Root laden ----
            char filepath[2048];

            // "/" → "/index.html"
            if (strcmp(path, "/") == 0) {
                snprintf(filepath, sizeof(filepath), "%s/index.html", httproot);
            } else {
                snprintf(filepath, sizeof(filepath), "%s%s", httproot, path);
            }

            struct stat st;
            if (stat(filepath, &st) == 0 && S_ISREG(st.st_mode)) {
                int fd = open(filepath, O_RDONLY);
                if (fd < 0) {
                    snprintf(response, sizeof(response),
                             "HTTP/1.1 500 Internal Server Error\r\n"
                             "Connection: close\r\n\r\n");
                    send(client_fd, response, strlen(response), 0);
                } else {
                    char filebuf[BUF_SIZE];
                    int n = read(fd, filebuf, sizeof(filebuf));
                    close(fd);

                    snprintf(response, sizeof(response),
                             "HTTP/1.1 200 OK\r\n"
                             "Server: httpsrv\r\n"
                             "Content-Type: %s\r\n"
                             "Content-Length: %d\r\n"
                             "Connection: close\r\n"
                             "\r\n",
                             get_content_type(filepath), n);

                    send(client_fd, response, strlen(response), 0);
                    send(client_fd, filebuf, n, 0);
                }
            } else {
                snprintf(response, sizeof(response),
                         "HTTP/1.1 404 Not Found\r\n"
                         "Connection: close\r\n\r\n");
                send(client_fd, response, strlen(response), 0);
            }
        }

        shutdown(client_fd, SHUT_WR);
        close(client_fd);
    }
}