From 5019c543808e1de9585282a2dbc951cf951e0132 Mon Sep 17 00:00:00 2001
From: Masahiko AMANO <hiko-19@ya.ru>
Date: Wed, 4 Jan 2023 01:55:15 +0300
Subject: [PATCH] init(cgi): add Common Gateway Interface with authentication
 only

---
 CMakeLists.txt |   4 ++
 cgi/cgi.c      | 114 +++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 118 insertions(+)
 create mode 100644 cgi/cgi.c

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 03d1da6..be55947 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -28,3 +28,7 @@ add_library(tanabata SHARED ${TANABATA_SRC})
 
 # Tanabata CLI app
 add_executable(tfm ${TANABATA_SRC} ${CLI_SRC})
+
+# Authentication CGI app
+add_executable(tfm-cgi ${TANABATA_SRC} cgi/cgi.c)
+target_link_libraries(tfm-cgi fcgi ssl crypto pthread)
diff --git a/cgi/cgi.c b/cgi/cgi.c
new file mode 100644
index 0000000..2bfdbc3
--- /dev/null
+++ b/cgi/cgi.c
@@ -0,0 +1,114 @@
+#include <fcgi_stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include <openssl/sha.h>
+#include <pthread.h>
+
+#define TOKEN_RENTALTIME 604800
+#define TOKEN_SIZE 64
+
+static time_t SID;
+static char TOKEN[TOKEN_SIZE];
+static int socket_auth;
+static int socket_cgi;
+
+int validate(FCGX_Request *request) {
+    if (time(NULL) - SID > TOKEN_RENTALTIME) {
+        return 1;
+    }
+    char token[TOKEN_SIZE];
+    FCGX_GetStr(token, TOKEN_SIZE, request->in);
+    if (memcmp(token, TOKEN, TOKEN_SIZE) == 0) {
+        return 0;
+    }
+    return 1;
+}
+
+static void *auth() {
+    FCGX_Request request;
+    if (FCGX_InitRequest(&request, socket_auth, FCGI_FAIL_ACCEPT_ON_INTR) != 0) {
+        exit(1);
+    }
+    unsigned char password[SHA256_DIGEST_LENGTH];
+    FILE *passfile = fopen("/etc/tfm/password", "rb");
+    if (passfile == NULL ||
+        fread(password, 1, SHA256_DIGEST_LENGTH, passfile) < SHA256_DIGEST_LENGTH) {
+        exit(1);
+    }
+    fclose(passfile);
+    int rc;
+    char buffer[33];
+    for (;;) {
+        static pthread_mutex_t accept_mutex = PTHREAD_MUTEX_INITIALIZER;
+        pthread_mutex_lock(&accept_mutex);
+        rc = FCGX_Accept_r(&request);
+        pthread_mutex_unlock(&accept_mutex);
+        if (rc < 0) {
+            break;
+        }
+        memset(buffer, 0, 33);
+        FCGX_GetStr(buffer, 32, request.in);
+        unsigned char hash[SHA256_DIGEST_LENGTH];
+        SHA256((const unsigned char *) buffer, strlen(buffer), hash);
+        if (memcmp(hash, password, SHA256_DIGEST_LENGTH) == 0) {
+            time(&SID);
+            uint64_t subtoken = SID;
+            SHA256((const unsigned char *) &subtoken, 8, hash);
+            for (int i = 0; i < SHA256_DIGEST_LENGTH; i++) {
+                sprintf(TOKEN + (i * 2), "%02x", hash[i]);
+            }
+            FCGX_PutS("Content-type: application/json\r\n\r\n"
+                      "{\"status\":true,\"token\":\"", request.out);
+            FCGX_PutS(TOKEN, request.out);
+            FCGX_PutS("\"}\n", request.out);
+            FCGX_Finish_r(&request);
+            continue;
+        }
+        FCGX_PutS("Content-type: application/json\r\n\r\n"
+                  "{\"status\":false}\n", request.out);
+        FCGX_Finish_r(&request);
+    }
+    return NULL;
+}
+
+static void *tfmcgi() {
+    FCGX_Request request;
+    if (FCGX_InitRequest(&request, socket_cgi, FCGI_FAIL_ACCEPT_ON_INTR) != 0) {
+        exit(1);
+    }
+    int rc;
+    for (;;) {
+        static pthread_mutex_t accept_mutex = PTHREAD_MUTEX_INITIALIZER;
+        pthread_mutex_lock(&accept_mutex);
+        rc = FCGX_Accept_r(&request);
+        pthread_mutex_unlock(&accept_mutex);
+        if (rc < 0) {
+            break;
+        }
+        if (validate(&request) != 0) {
+            FCGX_PutS("Content-type: application/json\r\n\r\n"
+                      "{\"status\":false}\n", request.out);
+            FCGX_Finish_r(&request);
+            continue;
+        }
+        FCGX_PutS("Content-type: application/json\r\n\r\n"
+                  "{\"status\":true}\n", request.out);
+        FCGX_Finish_r(&request);
+    }
+    return NULL;
+}
+
+int main() {
+    pthread_t thread_auth, thread_cgi;
+    FCGX_Init();
+    if ((socket_auth = FCGX_OpenSocket("/tmp/tfm-auth.sock", 0)) == -1 ||
+        (socket_cgi = FCGX_OpenSocket("/tmp/tfm-cgi.sock", 0)) == -1) {
+        return 1;
+    }
+    pthread_create(&thread_auth, NULL, auth, NULL);
+    pthread_create(&thread_cgi, NULL, tfmcgi, NULL);
+    pthread_join(thread_auth, NULL);
+    pthread_join(thread_cgi, NULL);
+    return 0;
+}