/*
* A git credential helper that interface with Windows' Credential Manager
*
*/
#include <windows.h>
#include <stdio.h>
#include <io.h>
#include <fcntl.h>
/* common helpers */
#define ARRAY_SIZE(x) (sizeof(x)/sizeof(x[0]))
static void die(const char *err, ...)
{
char msg[4096];
va_list params;
va_start(params, err);
vsnprintf(msg, sizeof(msg), err, params);
fprintf(stderr, "%s\n", msg);
va_end(params);
exit(1);
}
static void *xmalloc(size_t size)
{
void *ret = malloc(size);
if (!ret && !size)
ret = malloc(1);
if (!ret)
die("Out of memory");
return ret;
}
/* MinGW doesn't have wincred.h, so we need to define stuff */
typedef struct _CREDENTIAL_ATTRIBUTEW {
LPWSTR Keyword;
DWORD Flags;
DWORD ValueSize;
LPBYTE Value;
} CREDENTIAL_ATTRIBUTEW, *PCREDENTIAL_ATTRIBUTEW;
typedef struct _CREDENTIALW {
DWORD Flags;
DWORD Type;
LPWSTR TargetName;
LPWSTR Comment;
FILETIME LastWritten;
DWORD CredentialBlobSize;
LPBYTE CredentialBlob;
DWORD Persist;
DWORD AttributeCount;
PCREDENTIAL_ATTRIBUTEW Attributes;
LPWSTR TargetAlias;
LPWSTR UserName;
} CREDENTIALW, *PCREDENTIALW;
#define CRED_TYPE_GENERIC 1
#define CRED_PERSIST_LOCAL_MACHINE 2
#define CRED_MAX_ATTRIBUTES 64
typedef BOOL (WINAPI *CredWriteWT)(PCREDENTIALW, DWORD);
typedef BOOL (WINAPI *CredEnumerateWT)(LPCWSTR, DWORD, DWORD *,
PCREDENTIALW **);
typedef VOID (WINAPI *CredFreeT)(PVOID);
typedef BOOL (WINAPI *CredDeleteWT)(LPCWSTR, DWORD, DWORD);
static HMODULE advapi;
static CredWriteWT CredWriteW;
static CredEnumerateWT CredEnumerateW;
static CredFreeT CredFree;
static CredDeleteWT CredDeleteW;
static void load_cred_funcs(void)
{
/* load DLLs */
advapi = LoadLibraryExA("advapi32.dll", NULL,
LOAD_LIBRARY_SEARCH_SYSTEM32);
if (!advapi)
die("failed to load advapi32.dll");
/* get function pointers */
CredWriteW = (CredWriteWT)GetProcAddress(advapi, "CredWriteW");
CredEnumerateW = (CredEnumerateWT)GetProcAddress(advapi,
"CredEnumerateW");
CredFree = (CredFreeT)GetProcAddress(advapi, "CredFree");
CredDeleteW = (CredDeleteWT)GetProcAddress(advapi, "CredDeleteW");
if (!CredWriteW || !CredEnumerateW || !CredFree || !CredDeleteW)
die("failed to load functions");
}
static WCHAR *wusername, *password, *protocol, *host, *path, target[1024];
static void write_item(const char *what, LPCWSTR wbuf, int wlen)
{
char *buf;
if (!wbuf || !wlen) {
printf("%s=\n", what);
return;
}
int len = WideCharToMultiByte(CP_UTF8, 0, wbuf, wlen, NULL, 0, NULL,
FALSE);
buf = xmalloc(len);
if (!WideCharToMultiByte(CP_UTF8, 0, wbuf, wlen, buf, len, NULL, FALSE))
die("WideCharToMultiByte failed!");
printf("%s=", what);
fwrite(buf, 1, len, stdout);
putchar('\n');
free(buf);
}
/*
* Match an (optional) expected string and a delimiter in the target string,
* consuming the matched text by updating the target pointer.
*/
static LPCWSTR wcsstr_last(LPCWSTR str, LPCWSTR find)
{
LPCWSTR res = NULL, pos;
for (pos = wcsstr(str, find); pos; pos = wcsstr(pos + 1, find))
res = pos;
return res;
}
static int match_part_with_last(LPCWSTR *ptarget, LPCWSTR want, LPCWSTR delim, int last)
{
LPCWSTR delim_pos, start = *ptarget;
int len;
/* find start of delimiter (or end-of-string if delim is empty) */
if (*delim)
delim_pos = last ? wcsstr_last(start, delim) : wcsstr(start, delim);
else
delim_pos = start + wcslen(start);
/*
* match text up to delimiter, or end of string (e.g. the '/' after
* host is optional if not followed by a path)
*/
if (delim_pos)
len = delim_pos - start;
else
len = wcslen(start);
/* update ptarget if we either found a delimiter or need a match */
if (delim_pos || want)
*ptarget = delim_pos ? delim_pos + wcslen(delim) : start + len;
return !want || (!wcsncmp(want, start, len) && !want[len]);
}
static int match_part(LPCWSTR *ptarget, LPCWSTR want, LPCWSTR delim)
{
return match_part_with_last(ptarget, want, delim, 0);
}
static int match_part_last(LPCWSTR *ptarget, LPCWSTR want, LPCWSTR delim)
{
return match_part_with_last(ptarget, want, delim, 1);
}
static int match_cred(const CREDENTIALW *cred)
{
LPCWSTR target = cred->TargetName;
if (wusername && wcscmp(wusername, cred->UserName ? cred->UserName : L""))
return 0;
return match_part(&target, L"git", L":") &&
match_part(&target, protocol, L"://") &&
match_part_last(&target, wusername, L"@") &&
match_part(&target, host, L"/") &&
match_part(&target, path, L"");
}
static void get_credential(void)
{
CREDENTIALW **creds;
DWORD num_creds;
int i;
if (!CredEnumerateW(L"git:*", 0, &num_creds, &creds))
return;
/* search for the first credential that matches username */
for (i = 0; i < num_creds; ++i)
if (match_cred(creds[i])) {
write_item("username", creds[i]->UserName,
creds[i]->UserName ? wcslen(creds[i]->UserName) : 0);
write_item("password",
(LPCWSTR)creds[i]->CredentialBlob,
creds[i]->CredentialBlobSize / sizeof(WCHAR));
break;
}
CredFree(creds);
}
static void store_credential(void)
{
CREDENTIALW cred;
if (!wusername || !password)
return;
cred.Flags = 0;
cred.Type = CRED_TYPE_GENERIC;
cred.TargetName = target;
cred.Comment = L"saved by git-credential-wincred";
cred.CredentialBlobSize = (wcslen(password)) * sizeof(WCHAR);
cred.CredentialBlob = (LPVOID)password;
cred.Persist = CRED_PERSIST_LOCAL_MACHINE;
cred.AttributeCount = 0;
cred.Attributes = NULL;
cred.TargetAlias = NULL;
cred.UserName = wusername;
if (!CredWriteW(&cred, 0))
die("CredWrite failed");
}
static void erase_credential(void)
{
CREDENTIALW **creds;
DWORD num_creds;
int i;
if (!CredEnumerateW(L"git:*", 0, &num_creds, &creds))
return;
for (i = 0; i < num_creds; ++i) {
if (match_cred(creds[i]))
CredDeleteW(creds[i]->TargetName, creds[i]->Type, 0);
}
CredFree(creds);
}
static WCHAR *utf8_to_utf16_dup(const char *str)
{
int wlen = MultiByteToWideChar(CP_UTF8, 0, str, -1, NULL, 0);
WCHAR *wstr = xmalloc(sizeof(WCHAR) * wlen);
MultiByteToWideChar(CP_UTF8, 0, str, -1, wstr, wlen);
return wstr;
}
static void read_credential(void)
{
char buf[1024];
while (fgets(buf, sizeof(buf), stdin)) {
char *v;
int len = strlen(buf);
/* strip trailing CR / LF */
while (len && strchr("\r\n", buf[len - 1]))
buf[--len] = 0;
if (!*buf)
break;
v = strchr(buf, '=');
if (!v)
die("bad input: %s", buf);
*v++ = '\0';
if (!strcmp(buf, "protocol"))
protocol = utf8_to_utf16_dup(v);
else if (!strcmp(buf, "host"))
host = utf8_to_utf16_dup(v);
else if (!strcmp(buf, "path"))
path = utf8_to_utf16_dup(v);
else if (!strcmp(buf, "username")) {
wusername = utf8_to_utf16_dup(v);
} else if (!strcmp(buf, "password"))
password = utf8_to_utf16_dup(v);
else
die("unrecognized input");
}
}
int main(int argc, char *argv[])
{
const char *usage =
"usage: git credential-wincred <get|store|erase>\n";
if (!argv[1])
die(usage);
/* git use binary pipes to avoid CRLF-issues */
_setmode(_fileno(stdin), _O_BINARY);
_setmode(_fileno(stdout), _O_BINARY);
read_credential();
load_cred_funcs();
if (!protocol || !(host || path))
return 0;
/* prepare 'target', the unique key for the credential */
wcscpy(target, L"git:");
wcsncat(target, protocol, ARRAY_SIZE(target));
wcsncat(target, L"://", ARRAY_SIZE(target));
if (wusername) {
wcsncat(target, wusername, ARRAY_SIZE(target));
wcsncat(target, L"@", ARRAY_SIZE(target));
}
if (host)
wcsncat(target, host, ARRAY_SIZE(target));
if (path) {
wcsncat(target, L"/", ARRAY_SIZE(target));
wcsncat(target, path, ARRAY_SIZE(target));
}
if (!strcmp(argv[1], "get"))
get_credential();
else if (!strcmp(argv[1], "store"))
store_credential();
else if (!strcmp(argv[1], "erase"))
erase_credential();
/* otherwise, ignore unknown action */
return 0;
}
