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