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 static void die(const char *err, ...)
  13 {
  14         char msg[4096];
  15         va_list params;
  16         va_start(params, err);
  17         vsnprintf(msg, sizeof(msg), err, params);
  18         fprintf(stderr, "%s\n", msg);
  19         va_end(params);
  20         exit(1);
  21 }
  22
  23 static void *xmalloc(size_t size)
  24 {
  25         void *ret = malloc(size);
  26         if (!ret && !size)
  27                 ret = malloc(1);
  28         if (!ret)
  29                  die("Out of memory");
  30         return ret;
  31 }
  32
  33 static char *xstrdup(const char *str)
  34 {
  35         char *ret = strdup(str);
  36         if (!ret)
  37                 die("Out of memory");
  38         return ret;
  39 }
  40
  41 /* MinGW doesn't have wincred.h, so we need to define stuff */
  42
  43 typedef struct _CREDENTIAL_ATTRIBUTEW {
  44         LPWSTR Keyword;
  45         DWORD  Flags;
  46         DWORD  ValueSize;
  47         LPBYTE Value;
  48 } CREDENTIAL_ATTRIBUTEW, *PCREDENTIAL_ATTRIBUTEW;
  49
  50 typedef struct _CREDENTIALW {
  51         DWORD                  Flags;
  52         DWORD                  Type;
  53         LPWSTR                 TargetName;
  54         LPWSTR                 Comment;
  55         FILETIME               LastWritten;
  56         DWORD                  CredentialBlobSize;
  57         LPBYTE                 CredentialBlob;
  58         DWORD                  Persist;
  59         DWORD                  AttributeCount;
  60         PCREDENTIAL_ATTRIBUTEW Attributes;
  61         LPWSTR                 TargetAlias;
  62         LPWSTR                 UserName;
  63 } CREDENTIALW, *PCREDENTIALW;
  64
  65 #define CRED_TYPE_GENERIC 1
  66 #define CRED_PERSIST_LOCAL_MACHINE 2
  67 #define CRED_MAX_ATTRIBUTES 64
  68
  69 typedef BOOL (WINAPI *CredWriteWT)(PCREDENTIALW, DWORD);
  70 typedef BOOL (WINAPI *CredUnPackAuthenticationBufferWT)(DWORD, PVOID, DWORD,
  71     LPWSTR, DWORD *, LPWSTR, DWORD *, LPWSTR, DWORD *);
  72 typedef BOOL (WINAPI *CredEnumerateWT)(LPCWSTR, DWORD, DWORD *,
  73     PCREDENTIALW **);
  74 typedef BOOL (WINAPI *CredPackAuthenticationBufferWT)(DWORD, LPWSTR, LPWSTR,
  75     PBYTE, DWORD *);
  76 typedef VOID (WINAPI *CredFreeT)(PVOID);
  77 typedef BOOL (WINAPI *CredDeleteWT)(LPCWSTR, DWORD, DWORD);
  78
  79 static HMODULE advapi, credui;
  80 static CredWriteWT CredWriteW;
  81 static CredUnPackAuthenticationBufferWT CredUnPackAuthenticationBufferW;
  82 static CredEnumerateWT CredEnumerateW;
  83 static CredPackAuthenticationBufferWT CredPackAuthenticationBufferW;
  84 static CredFreeT CredFree;
  85 static CredDeleteWT CredDeleteW;
  86
  87 static void load_cred_funcs(void)
  88 {
  89         /* load DLLs */
  90         advapi = LoadLibrary("advapi32.dll");
  91         credui = LoadLibrary("credui.dll");
  92         if (!advapi || !credui)
  93                 die("failed to load DLLs");
  94
  95         /* get function pointers */
  96         CredWriteW = (CredWriteWT)GetProcAddress(advapi, "CredWriteW");
  97         CredUnPackAuthenticationBufferW = (CredUnPackAuthenticationBufferWT)
  98             GetProcAddress(credui, "CredUnPackAuthenticationBufferW");
  99         CredEnumerateW = (CredEnumerateWT)GetProcAddress(advapi,
 100             "CredEnumerateW");
 101         CredPackAuthenticationBufferW = (CredPackAuthenticationBufferWT)
 102             GetProcAddress(credui, "CredPackAuthenticationBufferW");
 103         CredFree = (CredFreeT)GetProcAddress(advapi, "CredFree");
 104         CredDeleteW = (CredDeleteWT)GetProcAddress(advapi, "CredDeleteW");
 105         if (!CredWriteW || !CredUnPackAuthenticationBufferW ||
 106             !CredEnumerateW || !CredPackAuthenticationBufferW || !CredFree ||
 107             !CredDeleteW)
 108                 die("failed to load functions");
 109 }
 110
 111 static char target_buf[1024];
 112 static char *protocol, *host, *path, *username;
 113 static WCHAR *wusername, *password, *target;
 114
 115 static void write_item(const char *what, WCHAR *wbuf)
 116 {
 117         char *buf;
 118         int len = WideCharToMultiByte(CP_UTF8, 0, wbuf, -1, NULL, 0, NULL,
 119             FALSE);
 120         buf = xmalloc(len);
 121
 122         if (!WideCharToMultiByte(CP_UTF8, 0, wbuf, -1, buf, len, NULL, FALSE))
 123                 die("WideCharToMultiByte failed!");
 124
 125         printf("%s=", what);
 126         fwrite(buf, 1, len - 1, stdout);
 127         putchar('\n');
 128         free(buf);
 129 }
 130
 131 static int match_attr(const CREDENTIALW *cred, const WCHAR *keyword,
 132     const char *want)
 133 {
 134         int i;
 135         if (!want)
 136                 return 1;
 137
 138         for (i = 0; i < cred->AttributeCount; ++i)
 139                 if (!wcscmp(cred->Attributes[i].Keyword, keyword))
 140                         return !strcmp((const char *)cred->Attributes[i].Value,
 141                             want);
 142
 143         return 0; /* not found */
 144 }
 145
 146 static int match_cred(const CREDENTIALW *cred)
 147 {
 148         return (!wusername || !wcscmp(wusername, cred->UserName)) &&
 149             match_attr(cred, L"git_protocol", protocol) &&
 150             match_attr(cred, L"git_host", host) &&
 151             match_attr(cred, L"git_path", path);
 152 }
 153
 154 static void get_credential(void)
 155 {
 156         WCHAR *user_buf, *pass_buf;
 157         DWORD user_buf_size = 0, pass_buf_size = 0;
 158         CREDENTIALW **creds, *cred = NULL;
 159         DWORD num_creds;
 160         int i;
 161
 162         if (!CredEnumerateW(L"git:*", 0, &num_creds, &creds))
 163                 return;
 164
 165         /* search for the first credential that matches username */
 166         for (i = 0; i < num_creds; ++i)
 167                 if (match_cred(creds[i])) {
 168                         cred = creds[i];
 169                         break;
 170                 }
 171         if (!cred)
 172                 return;
 173
 174         CredUnPackAuthenticationBufferW(0, cred->CredentialBlob,
 175             cred->CredentialBlobSize, NULL, &user_buf_size, NULL, NULL,
 176             NULL, &pass_buf_size);
 177
 178         user_buf = xmalloc(user_buf_size * sizeof(WCHAR));
 179         pass_buf = xmalloc(pass_buf_size * sizeof(WCHAR));
 180
 181         if (!CredUnPackAuthenticationBufferW(0, cred->CredentialBlob,
 182             cred->CredentialBlobSize, user_buf, &user_buf_size, NULL, NULL,
 183             pass_buf, &pass_buf_size))
 184                 die("CredUnPackAuthenticationBuffer failed");
 185
 186         CredFree(creds);
 187
 188         /* zero-terminate (sizes include zero-termination) */
 189         user_buf[user_buf_size - 1] = L'\0';
 190         pass_buf[pass_buf_size - 1] = L'\0';
 191
 192         write_item("username", user_buf);
 193         write_item("password", pass_buf);
 194
 195         free(user_buf);
 196         free(pass_buf);
 197 }
 198
 199 static void write_attr(CREDENTIAL_ATTRIBUTEW *attr, const WCHAR *keyword,
 200     const char *value)
 201 {
 202         attr->Keyword = (LPWSTR)keyword;
 203         attr->Flags = 0;
 204         attr->ValueSize = strlen(value) + 1; /* store zero-termination */
 205         attr->Value = (LPBYTE)value;
 206 }
 207
 208 static void store_credential(void)
 209 {
 210         CREDENTIALW cred;
 211         BYTE *auth_buf;
 212         DWORD auth_buf_size = 0;
 213         CREDENTIAL_ATTRIBUTEW attrs[CRED_MAX_ATTRIBUTES];
 214
 215         if (!wusername || !password)
 216                 return;
 217
 218         /* query buffer size */
 219         CredPackAuthenticationBufferW(0, wusername, password,
 220             NULL, &auth_buf_size);
 221
 222         auth_buf = xmalloc(auth_buf_size);
 223
 224         if (!CredPackAuthenticationBufferW(0, wusername, password,
 225             auth_buf, &auth_buf_size))
 226                 die("CredPackAuthenticationBuffer failed");
 227
 228         cred.Flags = 0;
 229         cred.Type = CRED_TYPE_GENERIC;
 230         cred.TargetName = target;
 231         cred.Comment = L"saved by git-credential-wincred";
 232         cred.CredentialBlobSize = auth_buf_size;
 233         cred.CredentialBlob = auth_buf;
 234         cred.Persist = CRED_PERSIST_LOCAL_MACHINE;
 235         cred.AttributeCount = 1;
 236         cred.Attributes = attrs;
 237         cred.TargetAlias = NULL;
 238         cred.UserName = wusername;
 239
 240         write_attr(attrs, L"git_protocol", protocol);
 241
 242         if (host) {
 243                 write_attr(attrs + cred.AttributeCount, L"git_host", host);
 244                 cred.AttributeCount++;
 245         }
 246
 247         if (path) {
 248                 write_attr(attrs + cred.AttributeCount, L"git_path", path);
 249                 cred.AttributeCount++;
 250         }
 251
 252         if (!CredWriteW(&cred, 0))
 253                 die("CredWrite failed");
 254 }
 255
 256 static void erase_credential(void)
 257 {
 258         CREDENTIALW **creds;
 259         DWORD num_creds;
 260         int i;
 261
 262         if (!CredEnumerateW(L"git:*", 0, &num_creds, &creds))
 263                 return;
 264
 265         for (i = 0; i < num_creds; ++i) {
 266                 if (match_cred(creds[i]))
 267                         CredDeleteW(creds[i]->TargetName, creds[i]->Type, 0);
 268         }
 269
 270         CredFree(creds);
 271 }
 272
 273 static WCHAR *utf8_to_utf16_dup(const char *str)
 274 {
 275         int wlen = MultiByteToWideChar(CP_UTF8, 0, str, -1, NULL, 0);
 276         WCHAR *wstr = xmalloc(sizeof(WCHAR) * wlen);
 277         MultiByteToWideChar(CP_UTF8, 0, str, -1, wstr, wlen);
 278         return wstr;
 279 }
 280
 281 static void read_credential(void)
 282 {
 283         char buf[1024];
 284
 285         while (fgets(buf, sizeof(buf), stdin)) {
 286                 char *v;
 287
 288                 if (!strcmp(buf, "\n"))
 289                         break;
 290                 buf[strlen(buf)-1] = '\0';
 291
 292                 v = strchr(buf, '=');
 293                 if (!v)
 294                         die("bad input: %s", buf);
 295                 *v++ = '\0';
 296
 297                 if (!strcmp(buf, "protocol"))
 298                         protocol = xstrdup(v);
 299                 else if (!strcmp(buf, "host"))
 300                         host = xstrdup(v);
 301                 else if (!strcmp(buf, "path"))
 302                         path = xstrdup(v);
 303                 else if (!strcmp(buf, "username")) {
 304                         username = xstrdup(v);
 305                         wusername = utf8_to_utf16_dup(v);
 306                 } else if (!strcmp(buf, "password"))
 307                         password = utf8_to_utf16_dup(v);
 308                 else
 309                         die("unrecognized input");
 310         }
 311 }
 312
 313 int main(int argc, char *argv[])
 314 {
 315         const char *usage =
 316             "Usage: git credential-wincred <get|store|erase>\n";
 317
 318         if (!argv[1])
 319                 die(usage);
 320
 321         /* git use binary pipes to avoid CRLF-issues */
 322         _setmode(_fileno(stdin), _O_BINARY);
 323         _setmode(_fileno(stdout), _O_BINARY);
 324
 325         read_credential();
 326
 327         load_cred_funcs();
 328
 329         if (!protocol || !(host || path))
 330                 return 0;
 331
 332         /* prepare 'target', the unique key for the credential */
 333         strncat(target_buf, "git:", sizeof(target_buf));
 334         strncat(target_buf, protocol, sizeof(target_buf));
 335         strncat(target_buf, "://", sizeof(target_buf));
 336         if (username) {
 337                 strncat(target_buf, username, sizeof(target_buf));
 338                 strncat(target_buf, "@", sizeof(target_buf));
 339         }
 340         if (host)
 341                 strncat(target_buf, host, sizeof(target_buf));
 342         if (path) {
 343                 strncat(target_buf, "/", sizeof(target_buf));
 344                 strncat(target_buf, path, sizeof(target_buf));
 345         }
 346
 347         target = utf8_to_utf16_dup(target_buf);
 348
 349         if (!strcmp(argv[1], "get"))
 350                 get_credential();
 351         else if (!strcmp(argv[1], "store"))
 352                 store_credential();
 353         else if (!strcmp(argv[1], "erase"))
 354                 erase_credential();
 355         /* otherwise, ignore unknown action */
 356         return 0;
 357 }