- python module to send credentials through a unix socket; needs work

Changed files:
    ucred/setup.py -> 1.1
    ucred/ucred.c -> 1.1

2 files changed, 257 insertions, 0 deletions

diff --git a/ucred/setup.py b/ucred/setup.py
new file mode 100644
index 0000000..1730c01
--- /dev/null
+++ b/ucred/setup.py
@@ -0,0 +1,4 @@
+from distutils.core import setup, Extension
+setup(name="ucred",#version="1.0",
+      ext_modules=[Extension("ucred", ["ucred.c"])])
+
diff --git a/ucred/ucred.c b/ucred/ucred.c
new file mode 100644
index 0000000..1a2d816
--- /dev/null
+++ b/ucred/ucred.c
@@ -0,0 +1,253 @@
+#include <Python.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <signal.h>
+
+PyObject *g_socketerror; // socket.error
+
+static PyObject *usockmsgs_sendmsg(PyObject *self, PyObject *args, PyObject *keywds);
+static PyObject *usockmsgs_recvmsg(PyObject *self, PyObject *args, PyObject *keywds);
+
+static PyMethodDef usockmsgsMethods[] = {
+    {"sendmsg", usockmsgs_sendmsg, METH_VARARGS|METH_KEYWORDS, NULL},
+    {"recvmsg", usockmsgs_recvmsg, METH_VARARGS|METH_KEYWORDS, NULL},
+    {NULL, NULL, 0, NULL}
+};
+
+void initusockmsgs(void) {
+    PyObject *module;
+    module = Py_InitModule("usockmsgs", usockmsgsMethods);
+//    if(-1 == PyModule_AddIntConstant(module, "SCM_RIGHTS", SCM_RIGHTS)) {
+//        return;
+//    }
+    if(-1 == PyModule_AddIntConstant(module, "SCM_CREDENTIALS", SCM_CREDENTIALS)) {
+        return;
+    }
+
+
+    module = PyImport_ImportModule("socket");
+    if(!module) {
+        return;
+    }
+    g_socketerror = PyObject_GetAttrString(module, "error");
+    if(!g_socketerror) {
+        return;
+    }
+}
+
+static PyObject *usockmsgs_sendmsg(PyObject *self, PyObject *args, PyObject *keywds) {
+    int fd;
+    int flags=0;
+    int ret;
+    char *cmsg_buf = NULL;
+    struct msghdr msg;
+    struct iovec iov[1];
+    PyObject *ancillary = NULL;
+//    char *host;
+//    int port;
+
+    static char *kwlist[] = {"fd",
+                             "data",
+//                             "host", "port",
+                             "flags",
+                             "ancillary",
+                             NULL};
+
+//    kill(0, SIGTRAP);
+    if (!PyArg_ParseTupleAndKeywords(args, keywds, "it#|iO", kwlist,
+            &fd,
+            &iov[0].iov_base,
+            &iov[0].iov_len,
+//            &host,
+//            &port,
+            &flags,
+            &ancillary)) {
+        return NULL;
+    }
+//    kill(0, SIGTRAP);
+
+    msg.msg_name = NULL;
+    msg.msg_namelen = 0;
+
+    msg.msg_iov = iov;
+    msg.msg_iovlen = 1;
+
+    msg.msg_control = NULL;
+    msg.msg_controllen = 0;
+
+    msg.msg_flags = 0;
+
+    if(ancillary) {
+        struct cmsghdr *cur;
+        char *data, *cmsg_data;
+        int data_len, type, level;
+
+        if(!PyArg_ParseTuple(ancillary, "iit#",
+                &level,
+                &type,
+                &data,
+                &data_len)) {
+            return NULL;
+        }
+        cmsg_buf = malloc(CMSG_SPACE(data_len));
+        if (!cmsg_buf) {
+            PyErr_NoMemory();
+            return NULL;
+        }
+        msg.msg_control = cmsg_buf;
+        msg.msg_controllen = CMSG_SPACE(data_len);
+
+        cur = CMSG_FIRSTHDR(&msg);
+        cur->cmsg_level = level;
+        cur->cmsg_type = type;
+        cur->cmsg_len = CMSG_LEN(data_len);
+        cmsg_data = CMSG_DATA(cur);
+        memcpy(cmsg_data, data, data_len);
+        msg.msg_controllen = cur->cmsg_len; // ugh weird C API. CMSG_SPACE includes alignment, unline CMSG_LEN
+    }
+
+    ret = sendmsg(fd, &msg, flags);
+    free(cmsg_buf); // this is initialized to NULL and then, optionally, to return value of malloc
+    if(ret < 0) {
+        PyErr_SetFromErrno(g_socketerror);
+        return NULL;
+    }
+
+    return Py_BuildValue("i", ret);
+}
+
+#define CMSG_BUFSIZE (4*1024) // har har arbitrary and hopefully unused
+static PyObject *usockmsgs_recvmsg(PyObject *self, PyObject *args, PyObject *keywds) {
+    int fd;
+    int flags=0;
+    size_t maxsize=8192;
+    size_t cmsg_size=4*1024; // enough to store all file descriptors
+    int ret;
+    struct msghdr msg;
+    struct iovec iov[1];
+//    char cmsgbuf[CMSG_SPACE(CMSG_BUFSIZE)];
+    char *cmsgbuf;
+    PyObject *ancillary;
+
+    static char *kwlist[] = {"fd", "flags", "maxsize", "cmsg_size", NULL};
+
+    if (!PyArg_ParseTupleAndKeywords(args, keywds, "i|iii", kwlist,
+            &fd, &flags, &maxsize, &cmsg_size)) {
+        return NULL;
+    }
+    cmsg_size = CMSG_SPACE(cmsg_size);
+
+    msg.msg_name = NULL;
+    msg.msg_namelen = 0;
+
+    iov[0].iov_len = maxsize;
+    iov[0].iov_base = malloc(maxsize);
+    if (!iov[0].iov_base) {
+        PyErr_NoMemory();
+        return NULL;
+    }
+    msg.msg_iov = iov;
+    msg.msg_iovlen = 1;
+
+    cmsgbuf = malloc(cmsg_size);
+    if (!cmsgbuf) {
+        PyErr_NoMemory();
+        return NULL;
+    }
+    memset(cmsgbuf, 0, cmsg_size);
+    msg.msg_control = cmsgbuf;
+    msg.msg_controllen = cmsg_size;
+
+    ret = recvmsg(fd, &msg, flags);
+    if (ret < 0) {
+        PyErr_SetFromErrno(g_socketerror);
+        free(iov[0].iov_base);
+        free(cmsgbuf);
+        return NULL;
+    }
+
+    ancillary = PyList_New(0);
+    if (!ancillary) {
+        free(iov[0].iov_base);
+        free(cmsgbuf);
+        return NULL;
+    }
+
+    {
+        struct cmsghdr *cur;
+
+        for (cur=CMSG_FIRSTHDR(&msg); cur; cur=CMSG_NXTHDR(&msg, cur)) {
+            PyObject *entry;
+
+            assert(cur->cmsg_len >= sizeof(struct cmsghdr)); // no null ancillary data messages?
+
+            entry = Py_BuildValue("(iis#)",
+                        cur->cmsg_level,
+                        cur->cmsg_type,
+                        CMSG_DATA(cur),
+                        cur->cmsg_len - sizeof(struct cmsghdr));
+            if (PyList_Append(ancillary, entry) < 0) {
+                Py_DECREF(ancillary);
+                Py_DECREF(entry);
+                free(iov[0].iov_base);
+                free(cmsgbuf);
+                return NULL;
+            }
+        }
+    }
+
+    {
+        PyObject *r;
+        r = Py_BuildValue("s#iO",
+                iov[0].iov_base, ret,
+                msg.msg_flags,
+                ancillary);
+        free(iov[0].iov_base);
+        free(cmsgbuf);
+        return r;
+    }
+}
+
+// Useful code for sendmsg, multiple ancillary data case
+/*
+        iterator = PyObject_GetIter(ancillary); // TODO: Py_DECREF me everywhere!
+        if (!iterator) {
+            return NULL;
+        }
+        while ((item = PyIter_Next(iterator))) {
+            PyObject *rest;
+
+            if (!cur) {
+                Py_DECREF(iterator);
+                return NULL;
+            }
+
+            if (!PyArg_ParseTuple(item, "iiO",
+                    &cur->cmsg_level,
+                    &cur->cmsg_type,
+                    &rest)) {
+                return NULL;
+            }
+            char *data;
+            int len;
+
+            if (PyString_AsStringAndSize(rest, &data, &len)) {
+                return NULL;
+            }
+
+    memcpy(CMSG_DATA(cur), data, len);
+    cur->cmsg_len = CMSG_LEN(len);
+    real_controllen += CMSG_SPACE(len);
+     }
+
+      cur = CMSG_NXTHDR(&msg, cur);
+      Py_DECREF(item);
+    }
+    Py_DECREF(iterator);
+
+    if (PyErr_Occurred())
+      return NULL;
+
+    msg.msg_controllen = real_controllen;
+*/
+