feat: CGI script and sample HTML form

cgi/feuille.cgi.c

@@ -0,0 +1,168 @@
+/*
+ * misc/web/feuille.cgi.c
+ *  Auxiliary CGI script that converts an HTTP request to a raw TCP
+ *  one.
+ *
+ * Copyright (c) 2022
+ *     Tom MTT. <tom@heimdall.pm>
+ *
+ * This file is licensed under the 3-Clause BSD License.
+ * You should have received a copy of the 3-Clause BSD License
+ * along with this program. If not, see
+ * <https://basedwa.re/tmtt/feuille/src/branch/main/LICENSE>.
+ */
+
+#include <arpa/inet.h>   /* for inet_pton                                      */
+#include <errno.h>       /* for ERANGE, errno                                  */
+#include <netinet/in.h>  /* for htons, sockaddr_in, sockaddr_in6               */
+#include <stdio.h>       /* for printf, NULL, BUFSIZ                           */
+#include <stdlib.h>      /* for calloc, free, getenv, exit, strtoll            */
+#include <string.h>      /* for strcmp                                         */
+#include <strings.h>     /* for bzero                                          */
+#include <sys/socket.h>  /* for connect, socket, AF_INET, AF_INET6, recv, send */
+#include <unistd.h>      /* for close, read, STDIN_FILENO                      */
+
+/* Initialize client socket and connect to feuille */
+int initialize_socket(char *address, unsigned short port)
+{
+    int server;
+
+    /* initialize socket IPv4 and IPv6 addresses */
+    struct sockaddr_in server_address_v4;
+    bzero(&server_address_v4, sizeof(server_address_v4));
+
+    struct sockaddr_in6 server_address_v6;
+    bzero(&server_address_v6, sizeof(server_address_v6));
+
+    /* dirty hack to detect and convert IPv4 / IPv6 addresses */
+    if (inet_pton(AF_INET, address, &server_address_v4.sin_addr) == 1) {
+        /* set socket family and port */
+        server_address_v4.sin_family = AF_INET;
+        server_address_v4.sin_port   = htons(port);
+
+        /* create socket */
+        if ((server = socket(AF_INET, SOCK_STREAM, 0)) < 0)
+            return -1;
+
+        /* connect to server */
+        if (connect(server, (struct sockaddr *)&server_address_v4, sizeof(server_address_v4)) < 0)
+            return -1;
+
+    } else if (inet_pton(AF_INET6, address, &server_address_v6.sin6_addr) == 1) {
+        /* set socket family and port */
+        server_address_v6.sin6_family = AF_INET6;
+        server_address_v6.sin6_port   = htons(port);
+
+        /* create socket */
+        if ((server = socket(AF_INET6, SOCK_STREAM, 0)) < 0)
+            return -1;
+
+        /* connect to server */
+        if (connect(server, (struct sockaddr *)&server_address_v6, sizeof(server_address_v6)) < 0)
+            return -1;
+
+    } else
+        return -1;
+
+    return server;
+}
+
+/* CGI helper functions */
+void cgi_init()
+{
+    printf("Content-Type: text/plain\r\n");
+}
+
+void cgi_error(char *status)
+{
+    printf("Status: %s\r\n", status);
+    printf("\r\n");
+    printf("%s\n", status);
+}
+
+void cgi_die(char *status)
+{
+    cgi_error(status);
+    exit(1);
+}
+
+void cgi_ok(char *response)
+{
+    printf("Status: 200 OK\r\n");
+    printf("\r\n");
+    printf("%s", response);
+}
+
+void cgi_redirect(char *url)
+{
+    printf("Status: 301 Moved Permanently\r\n");
+    printf("Location: %s\r\n", url);
+    printf("\r\n");
+}
+
+/* main function */
+int main(void)
+{
+    cgi_init();
+
+    /* get method */
+    char *method;
+    if ((method = getenv("REQUEST_METHOD")) == NULL || strcmp(method, "POST") != 0)
+        cgi_die("405 Method Not Allowed");
+
+    /* get content length */
+    char *content_length;
+    if ((content_length = getenv("CONTENT_LENGTH")) == NULL)
+        cgi_die("400 Bad Request");
+
+    /* convert content length to a long long int */
+    long long length = strtoll(content_length, NULL, 10);
+    if (length <= 0 || errno == ERANGE)
+        cgi_die("400 Bad Request");
+
+    /* initialize socket */
+    int socket;
+    if ((socket = initialize_socket(ADDR, PORT)) == -1)
+        cgi_die("500 Internal Server Error");
+
+    /* read paste from stdin */
+    char *request;
+    if ((request = calloc(length + 1, sizeof(char))) == NULL)
+        cgi_die("500 Internal Server Error");
+
+    read(STDIN_FILENO, request, length);
+    request[length] = 0;
+
+    /* remove `paste=' from request */
+    char *paste = request;
+
+    char *offset;
+    if ((offset = strstr(request, "=")) != NULL) {
+        paste   = offset + 1;
+        length -= offset + 1 - request;
+    }
+
+    /* send paste to feuille */
+    send(socket, paste, length + 1, 0);
+    shutdown(socket, SHUT_WR);
+
+    /* receive response from feuille */
+    char *response;
+    if ((response = calloc(BUFSIZ + 1, sizeof(char))) == NULL)
+        cgi_die("500 Internal Server Error");
+
+    if (recv(socket, response, BUFSIZ, 0) > 0) {
+        if (strstr(response, "http") != NULL)
+            cgi_redirect(response);
+        else
+            cgi_ok(response);
+    } else
+        cgi_error("500 Internal Server Error");
+
+    /* close socket, free variables and exit */
+    close(socket);
+    free(response);
+    free(request);
+
+    return 0;
+}

cgi/form.html

@@ -0,0 +1,12 @@
+<!DOCTYPE html>
+<html>
+<head>
+
+</head>
+<body>
+    <form role="form" action="/cgi-bin/feuille.cgi" method="post" enctype="text/plain">
+        <textarea name="paste"></textarea>
+        <input type="submit" value="send paste">
+    </form>
+</body>
+</html>