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 = LoadLibraryExA("advapi32.dll", NULL,
  79                                 LOAD_LIBRARY_SEARCH_SYSTEM32);
  80         if (!advapi)
  81                 die("failed to load advapi32.dll");
  82
  83         /* get function pointers */
  84         CredWriteW = (CredWriteWT)GetProcAddress(advapi, "CredWriteW");
  85         CredEnumerateW = (CredEnumerateWT)GetProcAddress(advapi,
  86             "CredEnumerateW");
  87         CredFree = (CredFreeT)GetProcAddress(advapi, "CredFree");
  88         CredDeleteW = (CredDeleteWT)GetProcAddress(advapi, "CredDeleteW");
  89         if (!CredWriteW || !CredEnumerateW || !CredFree || !CredDeleteW)
  90                 die("failed to load functions");
  91 }
  92
  93 static WCHAR *wusername, *password, *protocol, *host, *path, target[1024];
  94
  95 static void write_item(const char *what, LPCWSTR wbuf, int wlen)
  96 {
  97         char *buf;
  98
  99         if (!wbuf || !wlen) {
 100                 printf("%s=\n", what);
 101                 return;
 102         }
 103
 104         int len = WideCharToMultiByte(CP_UTF8, 0, wbuf, wlen, NULL, 0, NULL,
 105             FALSE);
 106         buf = xmalloc(len);
 107
 108         if (!WideCharToMultiByte(CP_UTF8, 0, wbuf, wlen, buf, len, NULL, FALSE))
 109                 die("WideCharToMultiByte failed!");
 110
 111         printf("%s=", what);
 112         fwrite(buf, 1, len, stdout);
 113         putchar('\n');
 114         free(buf);
 115 }
 116
 117 /*
 118  * Match an (optional) expected string and a delimiter in the target string,
 119  * consuming the matched text by updating the target pointer.
 120  */
 121
 122 static LPCWSTR wcsstr_last(LPCWSTR str, LPCWSTR find)
 123 {
 124         LPCWSTR res = NULL, pos;
 125         for (pos = wcsstr(str, find); pos; pos = wcsstr(pos + 1, find))
 126                 res = pos;
 127         return res;
 128 }
 129
 130 static int match_part_with_last(LPCWSTR *ptarget, LPCWSTR want, LPCWSTR delim, int last)
 131 {
 132         LPCWSTR delim_pos, start = *ptarget;
 133         int len;
 134
 135         /* find start of delimiter (or end-of-string if delim is empty) */
 136         if (*delim)
 137                 delim_pos = last ? wcsstr_last(start, delim) : wcsstr(start, delim);
 138         else
 139                 delim_pos = start + wcslen(start);
 140
 141         /*
 142          * match text up to delimiter, or end of string (e.g. the '/' after
 143          * host is optional if not followed by a path)
 144          */
 145         if (delim_pos)
 146                 len = delim_pos - start;
 147         else
 148                 len = wcslen(start);
 149
 150         /* update ptarget if we either found a delimiter or need a match */
 151         if (delim_pos || want)
 152                 *ptarget = delim_pos ? delim_pos + wcslen(delim) : start + len;
 153
 154         return !want || (!wcsncmp(want, start, len) && !want[len]);
 155 }
 156
 157 static int match_part(LPCWSTR *ptarget, LPCWSTR want, LPCWSTR delim)
 158 {
 159         return match_part_with_last(ptarget, want, delim, 0);
 160 }
 161
 162 static int match_part_last(LPCWSTR *ptarget, LPCWSTR want, LPCWSTR delim)
 163 {
 164         return match_part_with_last(ptarget, want, delim, 1);
 165 }
 166
 167 static int match_cred(const CREDENTIALW *cred)
 168 {
 169         LPCWSTR target = cred->TargetName;
 170         if (wusername && wcscmp(wusername, cred->UserName ? cred->UserName : L""))
 171                 return 0;
 172
 173         return match_part(&target, L"git", L":") &&
 174                 match_part(&target, protocol, L"://") &&
 175                 match_part_last(&target, wusername, L"@") &&
 176                 match_part(&target, host, L"/") &&
 177                 match_part(&target, path, L"");
 178 }
 179
 180 static void get_credential(void)
 181 {
 182         CREDENTIALW **creds;
 183         DWORD num_creds;
 184         int i;
 185
 186         if (!CredEnumerateW(L"git:*", 0, &num_creds, &creds))
 187                 return;
 188
 189         /* search for the first credential that matches username */
 190         for (i = 0; i < num_creds; ++i)
 191                 if (match_cred(creds[i])) {
 192                         write_item("username", creds[i]->UserName,
 193                                 creds[i]->UserName ? wcslen(creds[i]->UserName) : 0);
 194                         write_item("password",
 195                                 (LPCWSTR)creds[i]->CredentialBlob,
 196                                 creds[i]->CredentialBlobSize / sizeof(WCHAR));
 197                         break;
 198                 }
 199
 200         CredFree(creds);
 201 }
 202
 203 static void store_credential(void)
 204 {
 205         CREDENTIALW cred;
 206
 207         if (!wusername || !password)
 208                 return;
 209
 210         cred.Flags = 0;
 211         cred.Type = CRED_TYPE_GENERIC;
 212         cred.TargetName = target;
 213         cred.Comment = L"saved by git-credential-wincred";
 214         cred.CredentialBlobSize = (wcslen(password)) * sizeof(WCHAR);
 215         cred.CredentialBlob = (LPVOID)password;
 216         cred.Persist = CRED_PERSIST_LOCAL_MACHINE;
 217         cred.AttributeCount = 0;
 218         cred.Attributes = NULL;
 219         cred.TargetAlias = NULL;
 220         cred.UserName = wusername;
 221
 222         if (!CredWriteW(&cred, 0))
 223                 die("CredWrite failed");
 224 }
 225
 226 static void erase_credential(void)
 227 {
 228         CREDENTIALW **creds;
 229         DWORD num_creds;
 230         int i;
 231
 232         if (!CredEnumerateW(L"git:*", 0, &num_creds, &creds))
 233                 return;
 234
 235         for (i = 0; i < num_creds; ++i) {
 236                 if (match_cred(creds[i]))
 237                         CredDeleteW(creds[i]->TargetName, creds[i]->Type, 0);
 238         }
 239
 240         CredFree(creds);
 241 }
 242
 243 static WCHAR *utf8_to_utf16_dup(const char *str)
 244 {
 245         int wlen = MultiByteToWideChar(CP_UTF8, 0, str, -1, NULL, 0);
 246         WCHAR *wstr = xmalloc(sizeof(WCHAR) * wlen);
 247         MultiByteToWideChar(CP_UTF8, 0, str, -1, wstr, wlen);
 248         return wstr;
 249 }
 250
 251 static void read_credential(void)
 252 {
 253         char buf[1024];
 254
 255         while (fgets(buf, sizeof(buf), stdin)) {
 256                 char *v;
 257                 int len = strlen(buf);
 258                 /* strip trailing CR / LF */
 259                 while (len && strchr("\r\n", buf[len - 1]))
 260                         buf[--len] = 0;
 261
 262                 if (!*buf)
 263                         break;
 264
 265                 v = strchr(buf, '=');
 266                 if (!v)
 267                         die("bad input: %s", buf);
 268                 *v++ = '\0';
 269
 270                 if (!strcmp(buf, "protocol"))
 271                         protocol = utf8_to_utf16_dup(v);
 272                 else if (!strcmp(buf, "host"))
 273                         host = utf8_to_utf16_dup(v);
 274                 else if (!strcmp(buf, "path"))
 275                         path = utf8_to_utf16_dup(v);
 276                 else if (!strcmp(buf, "username")) {
 277                         wusername = utf8_to_utf16_dup(v);
 278                 } else if (!strcmp(buf, "password"))
 279                         password = utf8_to_utf16_dup(v);
 280                 else
 281                         die("unrecognized input");
 282         }
 283 }
 284
 285 int main(int argc, char *argv[])
 286 {
 287         const char *usage =
 288             "usage: git credential-wincred <get|store|erase>\n";
 289
 290         if (!argv[1])
 291                 die(usage);
 292
 293         /* git use binary pipes to avoid CRLF-issues */
 294         _setmode(_fileno(stdin), _O_BINARY);
 295         _setmode(_fileno(stdout), _O_BINARY);
 296
 297         read_credential();
 298
 299         load_cred_funcs();
 300
 301         if (!protocol || !(host || path))
 302                 return 0;
 303
 304         /* prepare 'target', the unique key for the credential */
 305         wcscpy(target, L"git:");
 306         wcsncat(target, protocol, ARRAY_SIZE(target));
 307         wcsncat(target, L"://", ARRAY_SIZE(target));
 308         if (wusername) {
 309                 wcsncat(target, wusername, ARRAY_SIZE(target));
 310                 wcsncat(target, L"@", ARRAY_SIZE(target));
 311         }
 312         if (host)
 313                 wcsncat(target, host, ARRAY_SIZE(target));
 314         if (path) {
 315                 wcsncat(target, L"/", ARRAY_SIZE(target));
 316                 wcsncat(target, path, ARRAY_SIZE(target));
 317         }
 318
 319         if (!strcmp(argv[1], "get"))
 320                 get_credential();
 321         else if (!strcmp(argv[1], "store"))
 322                 store_credential();
 323         else if (!strcmp(argv[1], "erase"))
 324                 erase_credential();
 325         /* otherwise, ignore unknown action */
 326         return 0;
 327 }