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
  98         if (!wbuf || !wlen) {
  99                 printf("%s=\n", what);
 100                 return;
 101         }
 102
 103         int len = WideCharToMultiByte(CP_UTF8, 0, wbuf, wlen, NULL, 0, NULL,
 104             FALSE);
 105         buf = xmalloc(len);
 106
 107         if (!WideCharToMultiByte(CP_UTF8, 0, wbuf, wlen, buf, len, NULL, FALSE))
 108                 die("WideCharToMultiByte failed!");
 109
 110         printf("%s=", what);
 111         fwrite(buf, 1, len, stdout);
 112         putchar('\n');
 113         free(buf);
 114 }
 115
 116 /*
 117  * Match an (optional) expected string and a delimiter in the target string,
 118  * consuming the matched text by updating the target pointer.
 119  */
 120
 121 static LPCWSTR wcsstr_last(LPCWSTR str, LPCWSTR find)
 122 {
 123         LPCWSTR res = NULL, pos;
 124         for (pos = wcsstr(str, find); pos; pos = wcsstr(pos + 1, find))
 125                 res = pos;
 126         return res;
 127 }
 128
 129 static int match_part_with_last(LPCWSTR *ptarget, LPCWSTR want, LPCWSTR delim, int last)
 130 {
 131         LPCWSTR delim_pos, start = *ptarget;
 132         int len;
 133
 134         /* find start of delimiter (or end-of-string if delim is empty) */
 135         if (*delim)
 136                 delim_pos = last ? wcsstr_last(start, delim) : wcsstr(start, delim);
 137         else
 138                 delim_pos = start + wcslen(start);
 139
 140         /*
 141          * match text up to delimiter, or end of string (e.g. the '/' after
 142          * host is optional if not followed by a path)
 143          */
 144         if (delim_pos)
 145                 len = delim_pos - start;
 146         else
 147                 len = wcslen(start);
 148
 149         /* update ptarget if we either found a delimiter or need a match */
 150         if (delim_pos || want)
 151                 *ptarget = delim_pos ? delim_pos + wcslen(delim) : start + len;
 152
 153         return !want || (!wcsncmp(want, start, len) && !want[len]);
 154 }
 155
 156 static int match_part(LPCWSTR *ptarget, LPCWSTR want, LPCWSTR delim)
 157 {
 158         return match_part_with_last(ptarget, want, delim, 0);
 159 }
 160
 161 static int match_part_last(LPCWSTR *ptarget, LPCWSTR want, LPCWSTR delim)
 162 {
 163         return match_part_with_last(ptarget, want, delim, 1);
 164 }
 165
 166 static int match_cred(const CREDENTIALW *cred)
 167 {
 168         LPCWSTR target = cred->TargetName;
 169         if (wusername && wcscmp(wusername, cred->UserName ? cred->UserName : L""))
 170                 return 0;
 171
 172         return match_part(&target, L"git", L":") &&
 173                 match_part(&target, protocol, L"://") &&
 174                 match_part_last(&target, wusername, L"@") &&
 175                 match_part(&target, host, L"/") &&
 176                 match_part(&target, path, L"");
 177 }
 178
 179 static void get_credential(void)
 180 {
 181         CREDENTIALW **creds;
 182         DWORD num_creds;
 183         int i;
 184
 185         if (!CredEnumerateW(L"git:*", 0, &num_creds, &creds))
 186                 return;
 187
 188         /* search for the first credential that matches username */
 189         for (i = 0; i < num_creds; ++i)
 190                 if (match_cred(creds[i])) {
 191                         write_item("username", creds[i]->UserName,
 192                                 creds[i]->UserName ? wcslen(creds[i]->UserName) : 0);
 193                         write_item("password",
 194                                 (LPCWSTR)creds[i]->CredentialBlob,
 195                                 creds[i]->CredentialBlobSize / sizeof(WCHAR));
 196                         break;
 197                 }
 198
 199         CredFree(creds);
 200 }
 201
 202 static void store_credential(void)
 203 {
 204         CREDENTIALW cred;
 205
 206         if (!wusername || !password)
 207                 return;
 208
 209         cred.Flags = 0;
 210         cred.Type = CRED_TYPE_GENERIC;
 211         cred.TargetName = target;
 212         cred.Comment = L"saved by git-credential-wincred";
 213         cred.CredentialBlobSize = (wcslen(password)) * sizeof(WCHAR);
 214         cred.CredentialBlob = (LPVOID)password;
 215         cred.Persist = CRED_PERSIST_LOCAL_MACHINE;
 216         cred.AttributeCount = 0;
 217         cred.Attributes = NULL;
 218         cred.TargetAlias = NULL;
 219         cred.UserName = wusername;
 220
 221         if (!CredWriteW(&cred, 0))
 222                 die("CredWrite failed");
 223 }
 224
 225 static void erase_credential(void)
 226 {
 227         CREDENTIALW **creds;
 228         DWORD num_creds;
 229         int i;
 230
 231         if (!CredEnumerateW(L"git:*", 0, &num_creds, &creds))
 232                 return;
 233
 234         for (i = 0; i < num_creds; ++i) {
 235                 if (match_cred(creds[i]))
 236                         CredDeleteW(creds[i]->TargetName, creds[i]->Type, 0);
 237         }
 238
 239         CredFree(creds);
 240 }
 241
 242 static WCHAR *utf8_to_utf16_dup(const char *str)
 243 {
 244         int wlen = MultiByteToWideChar(CP_UTF8, 0, str, -1, NULL, 0);
 245         WCHAR *wstr = xmalloc(sizeof(WCHAR) * wlen);
 246         MultiByteToWideChar(CP_UTF8, 0, str, -1, wstr, wlen);
 247         return wstr;
 248 }
 249
 250 static void read_credential(void)
 251 {
 252         char buf[1024];
 253
 254         while (fgets(buf, sizeof(buf), stdin)) {
 255                 char *v;
 256                 int len = strlen(buf);
 257                 /* strip trailing CR / LF */
 258                 while (len && strchr("\r\n", buf[len - 1]))
 259                         buf[--len] = 0;
 260
 261                 if (!*buf)
 262                         break;
 263
 264                 v = strchr(buf, '=');
 265                 if (!v)
 266                         die("bad input: %s", buf);
 267                 *v++ = '\0';
 268
 269                 if (!strcmp(buf, "protocol"))
 270                         protocol = utf8_to_utf16_dup(v);
 271                 else if (!strcmp(buf, "host"))
 272                         host = utf8_to_utf16_dup(v);
 273                 else if (!strcmp(buf, "path"))
 274                         path = utf8_to_utf16_dup(v);
 275                 else if (!strcmp(buf, "username")) {
 276                         wusername = utf8_to_utf16_dup(v);
 277                 } else if (!strcmp(buf, "password"))
 278                         password = utf8_to_utf16_dup(v);
 279                 else
 280                         die("unrecognized input");
 281         }
 282 }
 283
 284 int main(int argc, char *argv[])
 285 {
 286         const char *usage =
 287             "usage: git credential-wincred <get|store|erase>\n";
 288
 289         if (!argv[1])
 290                 die(usage);
 291
 292         /* git use binary pipes to avoid CRLF-issues */
 293         _setmode(_fileno(stdin), _O_BINARY);
 294         _setmode(_fileno(stdout), _O_BINARY);
 295
 296         read_credential();
 297
 298         load_cred_funcs();
 299
 300         if (!protocol || !(host || path))
 301                 return 0;
 302
 303         /* prepare 'target', the unique key for the credential */
 304         wcscpy(target, L"git:");
 305         wcsncat(target, protocol, ARRAY_SIZE(target));
 306         wcsncat(target, L"://", ARRAY_SIZE(target));
 307         if (wusername) {
 308                 wcsncat(target, wusername, ARRAY_SIZE(target));
 309                 wcsncat(target, L"@", ARRAY_SIZE(target));
 310         }
 311         if (host)
 312                 wcsncat(target, host, ARRAY_SIZE(target));
 313         if (path) {
 314                 wcsncat(target, L"/", ARRAY_SIZE(target));
 315                 wcsncat(target, path, ARRAY_SIZE(target));
 316         }
 317
 318         if (!strcmp(argv[1], "get"))
 319                 get_credential();
 320         else if (!strcmp(argv[1], "store"))
 321                 store_credential();
 322         else if (!strcmp(argv[1], "erase"))
 323                 erase_credential();
 324         /* otherwise, ignore unknown action */
 325         return 0;
 326 }