contrib/credential/wincred/git-credential-wincred.c

   1 /*
   2  * A git credential helper that interface with Windows' Credential Manager
   3  *
   4  */
   5 #include <windows.h>
   6 #include <stdio.h>
   7 #include <io.h>
   8 #include <fcntl.h>
   9
  10 /* common helpers */
  11
  12 #define ARRAY_SIZE(x) (sizeof(x)/sizeof(x[0]))
  13
  14 static void die(const char *err, ...)
  15 {
  16         char msg[4096];
  17         va_list params;
  18         va_start(params, err);
  19         vsnprintf(msg, sizeof(msg), err, params);
  20         fprintf(stderr, "%s\n", msg);
  21         va_end(params);
  22         exit(1);
  23 }
  24
  25 static void *xmalloc(size_t size)
  26 {
  27         void *ret = malloc(size);
  28         if (!ret && !size)
  29                 ret = malloc(1);
  30         if (!ret)
  31                  die("Out of memory");
  32         return ret;
  33 }
  34
  35 /* MinGW doesn't have wincred.h, so we need to define stuff */
  36
  37 typedef struct _CREDENTIAL_ATTRIBUTEW {
  38         LPWSTR Keyword;
  39         DWORD  Flags;
  40         DWORD  ValueSize;
  41         LPBYTE Value;
  42 } CREDENTIAL_ATTRIBUTEW, *PCREDENTIAL_ATTRIBUTEW;
  43
  44 typedef struct _CREDENTIALW {
  45         DWORD                  Flags;
  46         DWORD                  Type;
  47         LPWSTR                 TargetName;
  48         LPWSTR                 Comment;
  49         FILETIME               LastWritten;
  50         DWORD                  CredentialBlobSize;
  51         LPBYTE                 CredentialBlob;
  52         DWORD                  Persist;
  53         DWORD                  AttributeCount;
  54         PCREDENTIAL_ATTRIBUTEW Attributes;
  55         LPWSTR                 TargetAlias;
  56         LPWSTR                 UserName;
  57 } CREDENTIALW, *PCREDENTIALW;
  58
  59 #define CRED_TYPE_GENERIC 1
  60 #define CRED_PERSIST_LOCAL_MACHINE 2
  61 #define CRED_MAX_ATTRIBUTES 64
  62
  63 typedef BOOL (WINAPI *CredWriteWT)(PCREDENTIALW, DWORD);
  64 typedef BOOL (WINAPI *CredEnumerateWT)(LPCWSTR, DWORD, DWORD *,
  65     PCREDENTIALW **);
  66 typedef VOID (WINAPI *CredFreeT)(PVOID);
  67 typedef BOOL (WINAPI *CredDeleteWT)(LPCWSTR, DWORD, DWORD);
  68
  69 static HMODULE advapi;
  70 static CredWriteWT CredWriteW;
  71 static CredEnumerateWT CredEnumerateW;
  72 static CredFreeT CredFree;
  73 static CredDeleteWT CredDeleteW;
  74
  75 static void load_cred_funcs(void)
  76 {
  77         /* load DLLs */
  78         advapi = LoadLibrary("advapi32.dll");
  79         if (!advapi)
  80                 die("failed to load advapi32.dll");
  81
  82         /* get function pointers */
  83         CredWriteW = (CredWriteWT)GetProcAddress(advapi, "CredWriteW");
  84         CredEnumerateW = (CredEnumerateWT)GetProcAddress(advapi,
  85             "CredEnumerateW");
  86         CredFree = (CredFreeT)GetProcAddress(advapi, "CredFree");
  87         CredDeleteW = (CredDeleteWT)GetProcAddress(advapi, "CredDeleteW");
  88         if (!CredWriteW || !CredEnumerateW || !CredFree || !CredDeleteW)
  89                 die("failed to load functions");
  90 }
  91
  92 static WCHAR *wusername, *password, *protocol, *host, *path, target[1024];
  93
  94 static void write_item(const char *what, LPCWSTR wbuf, int wlen)
  95 {
  96         char *buf;
  97         int len = WideCharToMultiByte(CP_UTF8, 0, wbuf, wlen, NULL, 0, NULL,
  98             FALSE);
  99         buf = xmalloc(len);
 100
 101         if (!WideCharToMultiByte(CP_UTF8, 0, wbuf, wlen, buf, len, NULL, FALSE))
 102                 die("WideCharToMultiByte failed!");
 103
 104         printf("%s=", what);
 105         fwrite(buf, 1, len, stdout);
 106         putchar('\n');
 107         free(buf);
 108 }
 109
 110 /*
 111  * Match an (optional) expected string and a delimiter in the target string,
 112  * consuming the matched text by updating the target pointer.
 113  */
 114 static int match_part(LPCWSTR *ptarget, LPCWSTR want, LPCWSTR delim)
 115 {
 116         LPCWSTR delim_pos, start = *ptarget;
 117         int len;
 118
 119         /* find start of delimiter (or end-of-string if delim is empty) */
 120         if (*delim)
 121                 delim_pos = wcsstr(start, delim);
 122         else
 123                 delim_pos = start + wcslen(start);
 124
 125         /*
 126          * match text up to delimiter, or end of string (e.g. the '/' after
 127          * host is optional if not followed by a path)
 128          */
 129         if (delim_pos)
 130                 len = delim_pos - start;
 131         else
 132                 len = wcslen(start);
 133
 134         /* update ptarget if we either found a delimiter or need a match */
 135         if (delim_pos || want)
 136                 *ptarget = delim_pos ? delim_pos + wcslen(delim) : start + len;
 137
 138         return !want || (!wcsncmp(want, start, len) && !want[len]);
 139 }
 140
 141 static int match_cred(const CREDENTIALW *cred)
 142 {
 143         LPCWSTR target = cred->TargetName;
 144         if (wusername && wcscmp(wusername, cred->UserName))
 145                 return 0;
 146
 147         return match_part(&target, L"git", L":") &&
 148                 match_part(&target, protocol, L"://") &&
 149                 match_part(&target, wusername, L"@") &&
 150                 match_part(&target, host, L"/") &&
 151                 match_part(&target, path, L"");
 152 }
 153
 154 static void get_credential(void)
 155 {
 156         CREDENTIALW **creds;
 157         DWORD num_creds;
 158         int i;
 159
 160         if (!CredEnumerateW(L"git:*", 0, &num_creds, &creds))
 161                 return;
 162
 163         /* search for the first credential that matches username */
 164         for (i = 0; i < num_creds; ++i)
 165                 if (match_cred(creds[i])) {
 166                         write_item("username", creds[i]->UserName,
 167                                 wcslen(creds[i]->UserName));
 168                         write_item("password",
 169                                 (LPCWSTR)creds[i]->CredentialBlob,
 170                                 creds[i]->CredentialBlobSize / sizeof(WCHAR));
 171                         break;
 172                 }
 173
 174         CredFree(creds);
 175 }
 176
 177 static void store_credential(void)
 178 {
 179         CREDENTIALW cred;
 180
 181         if (!wusername || !password)
 182                 return;
 183
 184         cred.Flags = 0;
 185         cred.Type = CRED_TYPE_GENERIC;
 186         cred.TargetName = target;
 187         cred.Comment = L"saved by git-credential-wincred";
 188         cred.CredentialBlobSize = (wcslen(password)) * sizeof(WCHAR);
 189         cred.CredentialBlob = (LPVOID)password;
 190         cred.Persist = CRED_PERSIST_LOCAL_MACHINE;
 191         cred.AttributeCount = 0;
 192         cred.Attributes = NULL;
 193         cred.TargetAlias = NULL;
 194         cred.UserName = wusername;
 195
 196         if (!CredWriteW(&cred, 0))
 197                 die("CredWrite failed");
 198 }
 199
 200 static void erase_credential(void)
 201 {
 202         CREDENTIALW **creds;
 203         DWORD num_creds;
 204         int i;
 205
 206         if (!CredEnumerateW(L"git:*", 0, &num_creds, &creds))
 207                 return;
 208
 209         for (i = 0; i < num_creds; ++i) {
 210                 if (match_cred(creds[i]))
 211                         CredDeleteW(creds[i]->TargetName, creds[i]->Type, 0);
 212         }
 213
 214         CredFree(creds);
 215 }
 216
 217 static WCHAR *utf8_to_utf16_dup(const char *str)
 218 {
 219         int wlen = MultiByteToWideChar(CP_UTF8, 0, str, -1, NULL, 0);
 220         WCHAR *wstr = xmalloc(sizeof(WCHAR) * wlen);
 221         MultiByteToWideChar(CP_UTF8, 0, str, -1, wstr, wlen);
 222         return wstr;
 223 }
 224
 225 static void read_credential(void)
 226 {
 227         char buf[1024];
 228
 229         while (fgets(buf, sizeof(buf), stdin)) {
 230                 char *v;
 231                 int len = strlen(buf);
 232                 /* strip trailing CR / LF */
 233                 while (len && strchr("\r\n", buf[len - 1]))
 234                         buf[--len] = 0;
 235
 236                 if (!*buf)
 237                         break;
 238
 239                 v = strchr(buf, '=');
 240                 if (!v)
 241                         die("bad input: %s", buf);
 242                 *v++ = '\0';
 243
 244                 if (!strcmp(buf, "protocol"))
 245                         protocol = utf8_to_utf16_dup(v);
 246                 else if (!strcmp(buf, "host"))
 247                         host = utf8_to_utf16_dup(v);
 248                 else if (!strcmp(buf, "path"))
 249                         path = utf8_to_utf16_dup(v);
 250                 else if (!strcmp(buf, "username")) {
 251                         wusername = utf8_to_utf16_dup(v);
 252                 } else if (!strcmp(buf, "password"))
 253                         password = utf8_to_utf16_dup(v);
 254                 else
 255                         die("unrecognized input");
 256         }
 257 }
 258
 259 int main(int argc, char *argv[])
 260 {
 261         const char *usage =
 262             "usage: git credential-wincred <get|store|erase>\n";
 263
 264         if (!argv[1])
 265                 die(usage);
 266
 267         /* git use binary pipes to avoid CRLF-issues */
 268         _setmode(_fileno(stdin), _O_BINARY);
 269         _setmode(_fileno(stdout), _O_BINARY);
 270
 271         read_credential();
 272
 273         load_cred_funcs();
 274
 275         if (!protocol || !(host || path))
 276                 return 0;
 277
 278         /* prepare 'target', the unique key for the credential */
 279         wcscpy(target, L"git:");
 280         wcsncat(target, protocol, ARRAY_SIZE(target));
 281         wcsncat(target, L"://", ARRAY_SIZE(target));
 282         if (wusername) {
 283                 wcsncat(target, wusername, ARRAY_SIZE(target));
 284                 wcsncat(target, L"@", ARRAY_SIZE(target));
 285         }
 286         if (host)
 287                 wcsncat(target, host, ARRAY_SIZE(target));
 288         if (path) {
 289                 wcsncat(target, L"/", ARRAY_SIZE(target));
 290                 wcsncat(target, path, ARRAY_SIZE(target));
 291         }
 292
 293         if (!strcmp(argv[1], "get"))
 294                 get_credential();
 295         else if (!strcmp(argv[1], "store"))
 296                 store_credential();
 297         else if (!strcmp(argv[1], "erase"))
 298                 erase_credential();
 299         /* otherwise, ignore unknown action */
 300         return 0;
 301 }