http.c

   1 #include "http.h"
   2 #include "pack.h"
   3 #include "sideband.h"
   4 #include "run-command.h"
   5 #include "url.h"
   6 #include "urlmatch.h"
   7 #include "credential.h"
   8 #include "version.h"
   9 #include "pkt-line.h"
  10
  11 int active_requests;
  12 int http_is_verbose;
  13 size_t http_post_buffer = 16 * LARGE_PACKET_MAX;
  14
  15 #if LIBCURL_VERSION_NUM >= 0x070a06
  16 #define LIBCURL_CAN_HANDLE_AUTH_ANY
  17 #endif
  18
  19 static int min_curl_sessions = 1;
  20 static int curl_session_count;
  21 #ifdef USE_CURL_MULTI
  22 static int max_requests = -1;
  23 static CURLM *curlm;
  24 #endif
  25 #ifndef NO_CURL_EASY_DUPHANDLE
  26 static CURL *curl_default;
  27 #endif
  28
  29 #define PREV_BUF_SIZE 4096
  30 #define RANGE_HEADER_SIZE 30
  31
  32 char curl_errorstr[CURL_ERROR_SIZE];
  33
  34 static int curl_ssl_verify = -1;
  35 static int curl_ssl_try;
  36 static const char *ssl_cert;
  37 #if LIBCURL_VERSION_NUM >= 0x070903
  38 static const char *ssl_key;
  39 #endif
  40 #if LIBCURL_VERSION_NUM >= 0x070908
  41 static const char *ssl_capath;
  42 #endif
  43 static const char *ssl_cainfo;
  44 static long curl_low_speed_limit = -1;
  45 static long curl_low_speed_time = -1;
  46 static int curl_ftp_no_epsv;
  47 static const char *curl_http_proxy;
  48 static const char *curl_cookie_file;
  49 static int curl_save_cookies;
  50 struct credential http_auth = CREDENTIAL_INIT;
  51 static int http_proactive_auth;
  52 static const char *user_agent;
  53
  54 #if LIBCURL_VERSION_NUM >= 0x071700
  55 /* Use CURLOPT_KEYPASSWD as is */
  56 #elif LIBCURL_VERSION_NUM >= 0x070903
  57 #define CURLOPT_KEYPASSWD CURLOPT_SSLKEYPASSWD
  58 #else
  59 #define CURLOPT_KEYPASSWD CURLOPT_SSLCERTPASSWD
  60 #endif
  61
  62 static struct credential cert_auth = CREDENTIAL_INIT;
  63 static int ssl_cert_password_required;
  64
  65 static struct curl_slist *pragma_header;
  66 static struct curl_slist *no_pragma_header;
  67
  68 static struct active_request_slot *active_queue_head;
  69
  70 size_t fread_buffer(char *ptr, size_t eltsize, size_t nmemb, void *buffer_)
  71 {
  72         size_t size = eltsize * nmemb;
  73         struct buffer *buffer = buffer_;
  74
  75         if (size > buffer->buf.len - buffer->posn)
  76                 size = buffer->buf.len - buffer->posn;
  77         memcpy(ptr, buffer->buf.buf + buffer->posn, size);
  78         buffer->posn += size;
  79
  80         return size;
  81 }
  82
  83 #ifndef NO_CURL_IOCTL
  84 curlioerr ioctl_buffer(CURL *handle, int cmd, void *clientp)
  85 {
  86         struct buffer *buffer = clientp;
  87
  88         switch (cmd) {
  89         case CURLIOCMD_NOP:
  90                 return CURLIOE_OK;
  91
  92         case CURLIOCMD_RESTARTREAD:
  93                 buffer->posn = 0;
  94                 return CURLIOE_OK;
  95
  96         default:
  97                 return CURLIOE_UNKNOWNCMD;
  98         }
  99 }
 100 #endif
 101
 102 size_t fwrite_buffer(char *ptr, size_t eltsize, size_t nmemb, void *buffer_)
 103 {
 104         size_t size = eltsize * nmemb;
 105         struct strbuf *buffer = buffer_;
 106
 107         strbuf_add(buffer, ptr, size);
 108         return size;
 109 }
 110
 111 size_t fwrite_null(char *ptr, size_t eltsize, size_t nmemb, void *strbuf)
 112 {
 113         return eltsize * nmemb;
 114 }
 115
 116 #ifdef USE_CURL_MULTI
 117 static void process_curl_messages(void)
 118 {
 119         int num_messages;
 120         struct active_request_slot *slot;
 121         CURLMsg *curl_message = curl_multi_info_read(curlm, &num_messages);
 122
 123         while (curl_message != NULL) {
 124                 if (curl_message->msg == CURLMSG_DONE) {
 125                         int curl_result = curl_message->data.result;
 126                         slot = active_queue_head;
 127                         while (slot != NULL &&
 128                                slot->curl != curl_message->easy_handle)
 129                                 slot = slot->next;
 130                         if (slot != NULL) {
 131                                 curl_multi_remove_handle(curlm, slot->curl);
 132                                 slot->curl_result = curl_result;
 133                                 finish_active_slot(slot);
 134                         } else {
 135                                 fprintf(stderr, "Received DONE message for unknown request!\n");
 136                         }
 137                 } else {
 138                         fprintf(stderr, "Unknown CURL message received: %d\n",
 139                                 (int)curl_message->msg);
 140                 }
 141                 curl_message = curl_multi_info_read(curlm, &num_messages);
 142         }
 143 }
 144 #endif
 145
 146 static int http_options(const char *var, const char *value, void *cb)
 147 {
 148         if (!strcmp("http.sslverify", var)) {
 149                 curl_ssl_verify = git_config_bool(var, value);
 150                 return 0;
 151         }
 152         if (!strcmp("http.sslcert", var))
 153                 return git_config_string(&ssl_cert, var, value);
 154 #if LIBCURL_VERSION_NUM >= 0x070903
 155         if (!strcmp("http.sslkey", var))
 156                 return git_config_string(&ssl_key, var, value);
 157 #endif
 158 #if LIBCURL_VERSION_NUM >= 0x070908
 159         if (!strcmp("http.sslcapath", var))
 160                 return git_config_string(&ssl_capath, var, value);
 161 #endif
 162         if (!strcmp("http.sslcainfo", var))
 163                 return git_config_string(&ssl_cainfo, var, value);
 164         if (!strcmp("http.sslcertpasswordprotected", var)) {
 165                 ssl_cert_password_required = git_config_bool(var, value);
 166                 return 0;
 167         }
 168         if (!strcmp("http.ssltry", var)) {
 169                 curl_ssl_try = git_config_bool(var, value);
 170                 return 0;
 171         }
 172         if (!strcmp("http.minsessions", var)) {
 173                 min_curl_sessions = git_config_int(var, value);
 174 #ifndef USE_CURL_MULTI
 175                 if (min_curl_sessions > 1)
 176                         min_curl_sessions = 1;
 177 #endif
 178                 return 0;
 179         }
 180 #ifdef USE_CURL_MULTI
 181         if (!strcmp("http.maxrequests", var)) {
 182                 max_requests = git_config_int(var, value);
 183                 return 0;
 184         }
 185 #endif
 186         if (!strcmp("http.lowspeedlimit", var)) {
 187                 curl_low_speed_limit = (long)git_config_int(var, value);
 188                 return 0;
 189         }
 190         if (!strcmp("http.lowspeedtime", var)) {
 191                 curl_low_speed_time = (long)git_config_int(var, value);
 192                 return 0;
 193         }
 194
 195         if (!strcmp("http.noepsv", var)) {
 196                 curl_ftp_no_epsv = git_config_bool(var, value);
 197                 return 0;
 198         }
 199         if (!strcmp("http.proxy", var))
 200                 return git_config_string(&curl_http_proxy, var, value);
 201
 202         if (!strcmp("http.cookiefile", var))
 203                 return git_config_string(&curl_cookie_file, var, value);
 204         if (!strcmp("http.savecookies", var)) {
 205                 curl_save_cookies = git_config_bool(var, value);
 206                 return 0;
 207         }
 208
 209         if (!strcmp("http.postbuffer", var)) {
 210                 http_post_buffer = git_config_int(var, value);
 211                 if (http_post_buffer < LARGE_PACKET_MAX)
 212                         http_post_buffer = LARGE_PACKET_MAX;
 213                 return 0;
 214         }
 215
 216         if (!strcmp("http.useragent", var))
 217                 return git_config_string(&user_agent, var, value);
 218
 219         /* Fall back on the default ones */
 220         return git_default_config(var, value, cb);
 221 }
 222
 223 static void init_curl_http_auth(CURL *result)
 224 {
 225         if (!http_auth.username)
 226                 return;
 227
 228         credential_fill(&http_auth);
 229
 230 #if LIBCURL_VERSION_NUM >= 0x071301
 231         curl_easy_setopt(result, CURLOPT_USERNAME, http_auth.username);
 232         curl_easy_setopt(result, CURLOPT_PASSWORD, http_auth.password);
 233 #else
 234         {
 235                 static struct strbuf up = STRBUF_INIT;
 236                 /*
 237                  * Note that we assume we only ever have a single set of
 238                  * credentials in a given program run, so we do not have
 239                  * to worry about updating this buffer, only setting its
 240                  * initial value.
 241                  */
 242                 if (!up.len)
 243                         strbuf_addf(&up, "%s:%s",
 244                                 http_auth.username, http_auth.password);
 245                 curl_easy_setopt(result, CURLOPT_USERPWD, up.buf);
 246         }
 247 #endif
 248 }
 249
 250 static int has_cert_password(void)
 251 {
 252         if (ssl_cert == NULL || ssl_cert_password_required != 1)
 253                 return 0;
 254         if (!cert_auth.password) {
 255                 cert_auth.protocol = xstrdup("cert");
 256                 cert_auth.username = xstrdup("");
 257                 cert_auth.path = xstrdup(ssl_cert);
 258                 credential_fill(&cert_auth);
 259         }
 260         return 1;
 261 }
 262
 263 #if LIBCURL_VERSION_NUM >= 0x071900
 264 static void set_curl_keepalive(CURL *c)
 265 {
 266         curl_easy_setopt(c, CURLOPT_TCP_KEEPALIVE, 1);
 267 }
 268
 269 #elif LIBCURL_VERSION_NUM >= 0x071000
 270 static int sockopt_callback(void *client, curl_socket_t fd, curlsocktype type)
 271 {
 272         int ka = 1;
 273         int rc;
 274         socklen_t len = (socklen_t)sizeof(ka);
 275
 276         if (type != CURLSOCKTYPE_IPCXN)
 277                 return 0;
 278
 279         rc = setsockopt(fd, SOL_SOCKET, SO_KEEPALIVE, (void *)&ka, len);
 280         if (rc < 0)
 281                 warning("unable to set SO_KEEPALIVE on socket %s",
 282                         strerror(errno));
 283
 284         return 0; /* CURL_SOCKOPT_OK only exists since curl 7.21.5 */
 285 }
 286
 287 static void set_curl_keepalive(CURL *c)
 288 {
 289         curl_easy_setopt(c, CURLOPT_SOCKOPTFUNCTION, sockopt_callback);
 290 }
 291
 292 #else
 293 static void set_curl_keepalive(CURL *c)
 294 {
 295         /* not supported on older curl versions */
 296 }
 297 #endif
 298
 299 static CURL *get_curl_handle(void)
 300 {
 301         CURL *result = curl_easy_init();
 302
 303         if (!curl_ssl_verify) {
 304                 curl_easy_setopt(result, CURLOPT_SSL_VERIFYPEER, 0);
 305                 curl_easy_setopt(result, CURLOPT_SSL_VERIFYHOST, 0);
 306         } else {
 307                 /* Verify authenticity of the peer's certificate */
 308                 curl_easy_setopt(result, CURLOPT_SSL_VERIFYPEER, 1);
 309                 /* The name in the cert must match whom we tried to connect */
 310                 curl_easy_setopt(result, CURLOPT_SSL_VERIFYHOST, 2);
 311         }
 312
 313 #if LIBCURL_VERSION_NUM >= 0x070907
 314         curl_easy_setopt(result, CURLOPT_NETRC, CURL_NETRC_OPTIONAL);
 315 #endif
 316 #ifdef LIBCURL_CAN_HANDLE_AUTH_ANY
 317         curl_easy_setopt(result, CURLOPT_HTTPAUTH, CURLAUTH_ANY);
 318 #endif
 319
 320         if (http_proactive_auth)
 321                 init_curl_http_auth(result);
 322
 323         if (ssl_cert != NULL)
 324                 curl_easy_setopt(result, CURLOPT_SSLCERT, ssl_cert);
 325         if (has_cert_password())
 326                 curl_easy_setopt(result, CURLOPT_KEYPASSWD, cert_auth.password);
 327 #if LIBCURL_VERSION_NUM >= 0x070903
 328         if (ssl_key != NULL)
 329                 curl_easy_setopt(result, CURLOPT_SSLKEY, ssl_key);
 330 #endif
 331 #if LIBCURL_VERSION_NUM >= 0x070908
 332         if (ssl_capath != NULL)
 333                 curl_easy_setopt(result, CURLOPT_CAPATH, ssl_capath);
 334 #endif
 335         if (ssl_cainfo != NULL)
 336                 curl_easy_setopt(result, CURLOPT_CAINFO, ssl_cainfo);
 337
 338         if (curl_low_speed_limit > 0 && curl_low_speed_time > 0) {
 339                 curl_easy_setopt(result, CURLOPT_LOW_SPEED_LIMIT,
 340                                  curl_low_speed_limit);
 341                 curl_easy_setopt(result, CURLOPT_LOW_SPEED_TIME,
 342                                  curl_low_speed_time);
 343         }
 344
 345         curl_easy_setopt(result, CURLOPT_FOLLOWLOCATION, 1);
 346 #if LIBCURL_VERSION_NUM >= 0x071301
 347         curl_easy_setopt(result, CURLOPT_POSTREDIR, CURL_REDIR_POST_ALL);
 348 #elif LIBCURL_VERSION_NUM >= 0x071101
 349         curl_easy_setopt(result, CURLOPT_POST301, 1);
 350 #endif
 351
 352         if (getenv("GIT_CURL_VERBOSE"))
 353                 curl_easy_setopt(result, CURLOPT_VERBOSE, 1);
 354
 355         curl_easy_setopt(result, CURLOPT_USERAGENT,
 356                 user_agent ? user_agent : git_user_agent());
 357
 358         if (curl_ftp_no_epsv)
 359                 curl_easy_setopt(result, CURLOPT_FTP_USE_EPSV, 0);
 360
 361 #ifdef CURLOPT_USE_SSL
 362         if (curl_ssl_try)
 363                 curl_easy_setopt(result, CURLOPT_USE_SSL, CURLUSESSL_TRY);
 364 #endif
 365
 366         if (curl_http_proxy) {
 367                 curl_easy_setopt(result, CURLOPT_PROXY, curl_http_proxy);
 368                 curl_easy_setopt(result, CURLOPT_PROXYAUTH, CURLAUTH_ANY);
 369         }
 370
 371         set_curl_keepalive(result);
 372
 373         return result;
 374 }
 375
 376 static void set_from_env(const char **var, const char *envname)
 377 {
 378         const char *val = getenv(envname);
 379         if (val)
 380                 *var = val;
 381 }
 382
 383 void http_init(struct remote *remote, const char *url, int proactive_auth)
 384 {
 385         char *low_speed_limit;
 386         char *low_speed_time;
 387         char *normalized_url;
 388         struct urlmatch_config config = { STRING_LIST_INIT_DUP };
 389
 390         config.section = "http";
 391         config.key = NULL;
 392         config.collect_fn = http_options;
 393         config.cascade_fn = git_default_config;
 394         config.cb = NULL;
 395
 396         http_is_verbose = 0;
 397         normalized_url = url_normalize(url, &config.url);
 398
 399         git_config(urlmatch_config_entry, &config);
 400         free(normalized_url);
 401
 402         curl_global_init(CURL_GLOBAL_ALL);
 403
 404         http_proactive_auth = proactive_auth;
 405
 406         if (remote && remote->http_proxy)
 407                 curl_http_proxy = xstrdup(remote->http_proxy);
 408
 409         pragma_header = curl_slist_append(pragma_header, "Pragma: no-cache");
 410         no_pragma_header = curl_slist_append(no_pragma_header, "Pragma:");
 411
 412 #ifdef USE_CURL_MULTI
 413         {
 414                 char *http_max_requests = getenv("GIT_HTTP_MAX_REQUESTS");
 415                 if (http_max_requests != NULL)
 416                         max_requests = atoi(http_max_requests);
 417         }
 418
 419         curlm = curl_multi_init();
 420         if (curlm == NULL) {
 421                 fprintf(stderr, "Error creating curl multi handle.\n");
 422                 exit(1);
 423         }
 424 #endif
 425
 426         if (getenv("GIT_SSL_NO_VERIFY"))
 427                 curl_ssl_verify = 0;
 428
 429         set_from_env(&ssl_cert, "GIT_SSL_CERT");
 430 #if LIBCURL_VERSION_NUM >= 0x070903
 431         set_from_env(&ssl_key, "GIT_SSL_KEY");
 432 #endif
 433 #if LIBCURL_VERSION_NUM >= 0x070908
 434         set_from_env(&ssl_capath, "GIT_SSL_CAPATH");
 435 #endif
 436         set_from_env(&ssl_cainfo, "GIT_SSL_CAINFO");
 437
 438         set_from_env(&user_agent, "GIT_HTTP_USER_AGENT");
 439
 440         low_speed_limit = getenv("GIT_HTTP_LOW_SPEED_LIMIT");
 441         if (low_speed_limit != NULL)
 442                 curl_low_speed_limit = strtol(low_speed_limit, NULL, 10);
 443         low_speed_time = getenv("GIT_HTTP_LOW_SPEED_TIME");
 444         if (low_speed_time != NULL)
 445                 curl_low_speed_time = strtol(low_speed_time, NULL, 10);
 446
 447         if (curl_ssl_verify == -1)
 448                 curl_ssl_verify = 1;
 449
 450         curl_session_count = 0;
 451 #ifdef USE_CURL_MULTI
 452         if (max_requests < 1)
 453                 max_requests = DEFAULT_MAX_REQUESTS;
 454 #endif
 455
 456         if (getenv("GIT_CURL_FTP_NO_EPSV"))
 457                 curl_ftp_no_epsv = 1;
 458
 459         if (url) {
 460                 credential_from_url(&http_auth, url);
 461                 if (!ssl_cert_password_required &&
 462                     getenv("GIT_SSL_CERT_PASSWORD_PROTECTED") &&
 463                     starts_with(url, "https://"))
 464                         ssl_cert_password_required = 1;
 465         }
 466
 467 #ifndef NO_CURL_EASY_DUPHANDLE
 468         curl_default = get_curl_handle();
 469 #endif
 470 }
 471
 472 void http_cleanup(void)
 473 {
 474         struct active_request_slot *slot = active_queue_head;
 475
 476         while (slot != NULL) {
 477                 struct active_request_slot *next = slot->next;
 478                 if (slot->curl != NULL) {
 479 #ifdef USE_CURL_MULTI
 480                         curl_multi_remove_handle(curlm, slot->curl);
 481 #endif
 482                         curl_easy_cleanup(slot->curl);
 483                 }
 484                 free(slot);
 485                 slot = next;
 486         }
 487         active_queue_head = NULL;
 488
 489 #ifndef NO_CURL_EASY_DUPHANDLE
 490         curl_easy_cleanup(curl_default);
 491 #endif
 492
 493 #ifdef USE_CURL_MULTI
 494         curl_multi_cleanup(curlm);
 495 #endif
 496         curl_global_cleanup();
 497
 498         curl_slist_free_all(pragma_header);
 499         pragma_header = NULL;
 500
 501         curl_slist_free_all(no_pragma_header);
 502         no_pragma_header = NULL;
 503
 504         if (curl_http_proxy) {
 505                 free((void *)curl_http_proxy);
 506                 curl_http_proxy = NULL;
 507         }
 508
 509         if (cert_auth.password != NULL) {
 510                 memset(cert_auth.password, 0, strlen(cert_auth.password));
 511                 free(cert_auth.password);
 512                 cert_auth.password = NULL;
 513         }
 514         ssl_cert_password_required = 0;
 515 }
 516
 517 struct active_request_slot *get_active_slot(void)
 518 {
 519         struct active_request_slot *slot = active_queue_head;
 520         struct active_request_slot *newslot;
 521
 522 #ifdef USE_CURL_MULTI
 523         int num_transfers;
 524
 525         /* Wait for a slot to open up if the queue is full */
 526         while (active_requests >= max_requests) {
 527                 curl_multi_perform(curlm, &num_transfers);
 528                 if (num_transfers < active_requests)
 529                         process_curl_messages();
 530         }
 531 #endif
 532
 533         while (slot != NULL && slot->in_use)
 534                 slot = slot->next;
 535
 536         if (slot == NULL) {
 537                 newslot = xmalloc(sizeof(*newslot));
 538                 newslot->curl = NULL;
 539                 newslot->in_use = 0;
 540                 newslot->next = NULL;
 541
 542                 slot = active_queue_head;
 543                 if (slot == NULL) {
 544                         active_queue_head = newslot;
 545                 } else {
 546                         while (slot->next != NULL)
 547                                 slot = slot->next;
 548                         slot->next = newslot;
 549                 }
 550                 slot = newslot;
 551         }
 552
 553         if (slot->curl == NULL) {
 554 #ifdef NO_CURL_EASY_DUPHANDLE
 555                 slot->curl = get_curl_handle();
 556 #else
 557                 slot->curl = curl_easy_duphandle(curl_default);
 558 #endif
 559                 curl_session_count++;
 560         }
 561
 562         active_requests++;
 563         slot->in_use = 1;
 564         slot->results = NULL;
 565         slot->finished = NULL;
 566         slot->callback_data = NULL;
 567         slot->callback_func = NULL;
 568         curl_easy_setopt(slot->curl, CURLOPT_COOKIEFILE, curl_cookie_file);
 569         if (curl_save_cookies)
 570                 curl_easy_setopt(slot->curl, CURLOPT_COOKIEJAR, curl_cookie_file);
 571         curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, pragma_header);
 572         curl_easy_setopt(slot->curl, CURLOPT_ERRORBUFFER, curl_errorstr);
 573         curl_easy_setopt(slot->curl, CURLOPT_CUSTOMREQUEST, NULL);
 574         curl_easy_setopt(slot->curl, CURLOPT_READFUNCTION, NULL);
 575         curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, NULL);
 576         curl_easy_setopt(slot->curl, CURLOPT_POSTFIELDS, NULL);
 577         curl_easy_setopt(slot->curl, CURLOPT_UPLOAD, 0);
 578         curl_easy_setopt(slot->curl, CURLOPT_HTTPGET, 1);
 579         curl_easy_setopt(slot->curl, CURLOPT_FAILONERROR, 1);
 580         if (http_auth.password)
 581                 init_curl_http_auth(slot->curl);
 582
 583         return slot;
 584 }
 585
 586 int start_active_slot(struct active_request_slot *slot)
 587 {
 588 #ifdef USE_CURL_MULTI
 589         CURLMcode curlm_result = curl_multi_add_handle(curlm, slot->curl);
 590         int num_transfers;
 591
 592         if (curlm_result != CURLM_OK &&
 593             curlm_result != CURLM_CALL_MULTI_PERFORM) {
 594                 active_requests--;
 595                 slot->in_use = 0;
 596                 return 0;
 597         }
 598
 599         /*
 600          * We know there must be something to do, since we just added
 601          * something.
 602          */
 603         curl_multi_perform(curlm, &num_transfers);
 604 #endif
 605         return 1;
 606 }
 607
 608 #ifdef USE_CURL_MULTI
 609 struct fill_chain {
 610         void *data;
 611         int (*fill)(void *);
 612         struct fill_chain *next;
 613 };
 614
 615 static struct fill_chain *fill_cfg;
 616
 617 void add_fill_function(void *data, int (*fill)(void *))
 618 {
 619         struct fill_chain *new = xmalloc(sizeof(*new));
 620         struct fill_chain **linkp = &fill_cfg;
 621         new->data = data;
 622         new->fill = fill;
 623         new->next = NULL;
 624         while (*linkp)
 625                 linkp = &(*linkp)->next;
 626         *linkp = new;
 627 }
 628
 629 void fill_active_slots(void)
 630 {
 631         struct active_request_slot *slot = active_queue_head;
 632
 633         while (active_requests < max_requests) {
 634                 struct fill_chain *fill;
 635                 for (fill = fill_cfg; fill; fill = fill->next)
 636                         if (fill->fill(fill->data))
 637                                 break;
 638
 639                 if (!fill)
 640                         break;
 641         }
 642
 643         while (slot != NULL) {
 644                 if (!slot->in_use && slot->curl != NULL
 645                         && curl_session_count > min_curl_sessions) {
 646                         curl_easy_cleanup(slot->curl);
 647                         slot->curl = NULL;
 648                         curl_session_count--;
 649                 }
 650                 slot = slot->next;
 651         }
 652 }
 653
 654 void step_active_slots(void)
 655 {
 656         int num_transfers;
 657         CURLMcode curlm_result;
 658
 659         do {
 660                 curlm_result = curl_multi_perform(curlm, &num_transfers);
 661         } while (curlm_result == CURLM_CALL_MULTI_PERFORM);
 662         if (num_transfers < active_requests) {
 663                 process_curl_messages();
 664                 fill_active_slots();
 665         }
 666 }
 667 #endif
 668
 669 void run_active_slot(struct active_request_slot *slot)
 670 {
 671 #ifdef USE_CURL_MULTI
 672         fd_set readfds;
 673         fd_set writefds;
 674         fd_set excfds;
 675         int max_fd;
 676         struct timeval select_timeout;
 677         int finished = 0;
 678
 679         slot->finished = &finished;
 680         while (!finished) {
 681                 step_active_slots();
 682
 683                 if (slot->in_use) {
 684 #if LIBCURL_VERSION_NUM >= 0x070f04
 685                         long curl_timeout;
 686                         curl_multi_timeout(curlm, &curl_timeout);
 687                         if (curl_timeout == 0) {
 688                                 continue;
 689                         } else if (curl_timeout == -1) {
 690                                 select_timeout.tv_sec  = 0;
 691                                 select_timeout.tv_usec = 50000;
 692                         } else {
 693                                 select_timeout.tv_sec  =  curl_timeout / 1000;
 694                                 select_timeout.tv_usec = (curl_timeout % 1000) * 1000;
 695                         }
 696 #else
 697                         select_timeout.tv_sec  = 0;
 698                         select_timeout.tv_usec = 50000;
 699 #endif
 700
 701                         max_fd = -1;
 702                         FD_ZERO(&readfds);
 703                         FD_ZERO(&writefds);
 704                         FD_ZERO(&excfds);
 705                         curl_multi_fdset(curlm, &readfds, &writefds, &excfds, &max_fd);
 706
 707                         /*
 708                          * It can happen that curl_multi_timeout returns a pathologically
 709                          * long timeout when curl_multi_fdset returns no file descriptors
 710                          * to read.  See commit message for more details.
 711                          */
 712                         if (max_fd < 0 &&
 713                             (select_timeout.tv_sec > 0 ||
 714                              select_timeout.tv_usec > 50000)) {
 715                                 select_timeout.tv_sec  = 0;
 716                                 select_timeout.tv_usec = 50000;
 717                         }
 718
 719                         select(max_fd+1, &readfds, &writefds, &excfds, &select_timeout);
 720                 }
 721         }
 722 #else
 723         while (slot->in_use) {
 724                 slot->curl_result = curl_easy_perform(slot->curl);
 725                 finish_active_slot(slot);
 726         }
 727 #endif
 728 }
 729
 730 static void closedown_active_slot(struct active_request_slot *slot)
 731 {
 732         active_requests--;
 733         slot->in_use = 0;
 734 }
 735
 736 static void release_active_slot(struct active_request_slot *slot)
 737 {
 738         closedown_active_slot(slot);
 739         if (slot->curl && curl_session_count > min_curl_sessions) {
 740 #ifdef USE_CURL_MULTI
 741                 curl_multi_remove_handle(curlm, slot->curl);
 742 #endif
 743                 curl_easy_cleanup(slot->curl);
 744                 slot->curl = NULL;
 745                 curl_session_count--;
 746         }
 747 #ifdef USE_CURL_MULTI
 748         fill_active_slots();
 749 #endif
 750 }
 751
 752 void finish_active_slot(struct active_request_slot *slot)
 753 {
 754         closedown_active_slot(slot);
 755         curl_easy_getinfo(slot->curl, CURLINFO_HTTP_CODE, &slot->http_code);
 756
 757         if (slot->finished != NULL)
 758                 (*slot->finished) = 1;
 759
 760         /* Store slot results so they can be read after the slot is reused */
 761         if (slot->results != NULL) {
 762                 slot->results->curl_result = slot->curl_result;
 763                 slot->results->http_code = slot->http_code;
 764 #if LIBCURL_VERSION_NUM >= 0x070a08
 765                 curl_easy_getinfo(slot->curl, CURLINFO_HTTPAUTH_AVAIL,
 766                                   &slot->results->auth_avail);
 767 #else
 768                 slot->results->auth_avail = 0;
 769 #endif
 770         }
 771
 772         /* Run callback if appropriate */
 773         if (slot->callback_func != NULL)
 774                 slot->callback_func(slot->callback_data);
 775 }
 776
 777 void finish_all_active_slots(void)
 778 {
 779         struct active_request_slot *slot = active_queue_head;
 780
 781         while (slot != NULL)
 782                 if (slot->in_use) {
 783                         run_active_slot(slot);
 784                         slot = active_queue_head;
 785                 } else {
 786                         slot = slot->next;
 787                 }
 788 }
 789
 790 /* Helpers for modifying and creating URLs */
 791 static inline int needs_quote(int ch)
 792 {
 793         if (((ch >= 'A') && (ch <= 'Z'))
 794                         || ((ch >= 'a') && (ch <= 'z'))
 795                         || ((ch >= '0') && (ch <= '9'))
 796                         || (ch == '/')
 797                         || (ch == '-')
 798                         || (ch == '.'))
 799                 return 0;
 800         return 1;
 801 }
 802
 803 static char *quote_ref_url(const char *base, const char *ref)
 804 {
 805         struct strbuf buf = STRBUF_INIT;
 806         const char *cp;
 807         int ch;
 808
 809         end_url_with_slash(&buf, base);
 810
 811         for (cp = ref; (ch = *cp) != 0; cp++)
 812                 if (needs_quote(ch))
 813                         strbuf_addf(&buf, "%%%02x", ch);
 814                 else
 815                         strbuf_addch(&buf, *cp);
 816
 817         return strbuf_detach(&buf, NULL);
 818 }
 819
 820 void append_remote_object_url(struct strbuf *buf, const char *url,
 821                               const char *hex,
 822                               int only_two_digit_prefix)
 823 {
 824         end_url_with_slash(buf, url);
 825
 826         strbuf_addf(buf, "objects/%.*s/", 2, hex);
 827         if (!only_two_digit_prefix)
 828                 strbuf_addf(buf, "%s", hex+2);
 829 }
 830
 831 char *get_remote_object_url(const char *url, const char *hex,
 832                             int only_two_digit_prefix)
 833 {
 834         struct strbuf buf = STRBUF_INIT;
 835         append_remote_object_url(&buf, url, hex, only_two_digit_prefix);
 836         return strbuf_detach(&buf, NULL);
 837 }
 838
 839 int handle_curl_result(struct slot_results *results)
 840 {
 841         /*
 842          * If we see a failing http code with CURLE_OK, we have turned off
 843          * FAILONERROR (to keep the server's custom error response), and should
 844          * translate the code into failure here.
 845          */
 846         if (results->curl_result == CURLE_OK &&
 847             results->http_code >= 400) {
 848                 results->curl_result = CURLE_HTTP_RETURNED_ERROR;
 849                 /*
 850                  * Normally curl will already have put the "reason phrase"
 851                  * from the server into curl_errorstr; unfortunately without
 852                  * FAILONERROR it is lost, so we can give only the numeric
 853                  * status code.
 854                  */
 855                 snprintf(curl_errorstr, sizeof(curl_errorstr),
 856                          "The requested URL returned error: %ld",
 857                          results->http_code);
 858         }
 859
 860         if (results->curl_result == CURLE_OK) {
 861                 credential_approve(&http_auth);
 862                 return HTTP_OK;
 863         } else if (missing_target(results))
 864                 return HTTP_MISSING_TARGET;
 865         else if (results->http_code == 401) {
 866                 if (http_auth.username && http_auth.password) {
 867                         credential_reject(&http_auth);
 868                         return HTTP_NOAUTH;
 869                 } else {
 870                         return HTTP_REAUTH;
 871                 }
 872         } else {
 873 #if LIBCURL_VERSION_NUM >= 0x070c00
 874                 if (!curl_errorstr[0])
 875                         strlcpy(curl_errorstr,
 876                                 curl_easy_strerror(results->curl_result),
 877                                 sizeof(curl_errorstr));
 878 #endif
 879                 return HTTP_ERROR;
 880         }
 881 }
 882
 883 int run_one_slot(struct active_request_slot *slot,
 884                  struct slot_results *results)
 885 {
 886         slot->results = results;
 887         if (!start_active_slot(slot)) {
 888                 snprintf(curl_errorstr, sizeof(curl_errorstr),
 889                          "failed to start HTTP request");
 890                 return HTTP_START_FAILED;
 891         }
 892
 893         run_active_slot(slot);
 894         return handle_curl_result(results);
 895 }
 896
 897 static CURLcode curlinfo_strbuf(CURL *curl, CURLINFO info, struct strbuf *buf)
 898 {
 899         char *ptr;
 900         CURLcode ret;
 901
 902         strbuf_reset(buf);
 903         ret = curl_easy_getinfo(curl, info, &ptr);
 904         if (!ret && ptr)
 905                 strbuf_addstr(buf, ptr);
 906         return ret;
 907 }
 908
 909 /* http_request() targets */
 910 #define HTTP_REQUEST_STRBUF     0
 911 #define HTTP_REQUEST_FILE       1
 912
 913 static int http_request(const char *url,
 914                         void *result, int target,
 915                         const struct http_get_options *options)
 916 {
 917         struct active_request_slot *slot;
 918         struct slot_results results;
 919         struct curl_slist *headers = NULL;
 920         struct strbuf buf = STRBUF_INIT;
 921         int ret;
 922
 923         slot = get_active_slot();
 924         curl_easy_setopt(slot->curl, CURLOPT_HTTPGET, 1);
 925
 926         if (result == NULL) {
 927                 curl_easy_setopt(slot->curl, CURLOPT_NOBODY, 1);
 928         } else {
 929                 curl_easy_setopt(slot->curl, CURLOPT_NOBODY, 0);
 930                 curl_easy_setopt(slot->curl, CURLOPT_FILE, result);
 931
 932                 if (target == HTTP_REQUEST_FILE) {
 933                         long posn = ftell(result);
 934                         curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION,
 935                                          fwrite);
 936                         if (posn > 0) {
 937                                 strbuf_addf(&buf, "Range: bytes=%ld-", posn);
 938                                 headers = curl_slist_append(headers, buf.buf);
 939                                 strbuf_reset(&buf);
 940                         }
 941                 } else
 942                         curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION,
 943                                          fwrite_buffer);
 944         }
 945
 946         strbuf_addstr(&buf, "Pragma:");
 947         if (options && options->no_cache)
 948                 strbuf_addstr(&buf, " no-cache");
 949         if (options && options->keep_error)
 950                 curl_easy_setopt(slot->curl, CURLOPT_FAILONERROR, 0);
 951
 952         headers = curl_slist_append(headers, buf.buf);
 953
 954         curl_easy_setopt(slot->curl, CURLOPT_URL, url);
 955         curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, headers);
 956         curl_easy_setopt(slot->curl, CURLOPT_ENCODING, "gzip");
 957
 958         ret = run_one_slot(slot, &results);
 959
 960         if (options && options->content_type)
 961                 curlinfo_strbuf(slot->curl, CURLINFO_CONTENT_TYPE,
 962                                 options->content_type);
 963
 964         if (options && options->effective_url)
 965                 curlinfo_strbuf(slot->curl, CURLINFO_EFFECTIVE_URL,
 966                                 options->effective_url);
 967
 968         curl_slist_free_all(headers);
 969         strbuf_release(&buf);
 970
 971         return ret;
 972 }
 973
 974 /*
 975  * Update the "base" url to a more appropriate value, as deduced by
 976  * redirects seen when requesting a URL starting with "url".
 977  *
 978  * The "asked" parameter is a URL that we asked curl to access, and must begin
 979  * with "base".
 980  *
 981  * The "got" parameter is the URL that curl reported to us as where we ended
 982  * up.
 983  *
 984  * Returns 1 if we updated the base url, 0 otherwise.
 985  *
 986  * Our basic strategy is to compare "base" and "asked" to find the bits
 987  * specific to our request. We then strip those bits off of "got" to yield the
 988  * new base. So for example, if our base is "http://example.com/foo.git",
 989  * and we ask for "http://example.com/foo.git/info/refs", we might end up
 990  * with "https://other.example.com/foo.git/info/refs". We would want the
 991  * new URL to become "https://other.example.com/foo.git".
 992  *
 993  * Note that this assumes a sane redirect scheme. It's entirely possible
 994  * in the example above to end up at a URL that does not even end in
 995  * "info/refs".  In such a case we simply punt, as there is not much we can
 996  * do (and such a scheme is unlikely to represent a real git repository,
 997  * which means we are likely about to abort anyway).
 998  */
 999 static int update_url_from_redirect(struct strbuf *base,
1000                                     const char *asked,
1001                                     const struct strbuf *got)
1002 {
1003         const char *tail;
1004         size_t tail_len;
1005
1006         if (!strcmp(asked, got->buf))
1007                 return 0;
1008
1009         if (!starts_with(asked, base->buf))
1010                 die("BUG: update_url_from_redirect: %s is not a superset of %s",
1011                     asked, base->buf);
1012
1013         tail = asked + base->len;
1014         tail_len = strlen(tail);
1015
1016         if (got->len < tail_len ||
1017             strcmp(tail, got->buf + got->len - tail_len))
1018                 return 0; /* insane redirect scheme */
1019
1020         strbuf_reset(base);
1021         strbuf_add(base, got->buf, got->len - tail_len);
1022         return 1;
1023 }
1024
1025 static int http_request_reauth(const char *url,
1026                                void *result, int target,
1027                                struct http_get_options *options)
1028 {
1029         int ret = http_request(url, result, target, options);
1030
1031         if (options && options->effective_url && options->base_url) {
1032                 if (update_url_from_redirect(options->base_url,
1033                                              url, options->effective_url)) {
1034                         credential_from_url(&http_auth, options->base_url->buf);
1035                         url = options->effective_url->buf;
1036                 }
1037         }
1038
1039         if (ret != HTTP_REAUTH)
1040                 return ret;
1041
1042         /*
1043          * If we are using KEEP_ERROR, the previous request may have
1044          * put cruft into our output stream; we should clear it out before
1045          * making our next request. We only know how to do this for
1046          * the strbuf case, but that is enough to satisfy current callers.
1047          */
1048         if (options && options->keep_error) {
1049                 switch (target) {
1050                 case HTTP_REQUEST_STRBUF:
1051                         strbuf_reset(result);
1052                         break;
1053                 default:
1054                         die("BUG: HTTP_KEEP_ERROR is only supported with strbufs");
1055                 }
1056         }
1057
1058         credential_fill(&http_auth);
1059
1060         return http_request(url, result, target, options);
1061 }
1062
1063 int http_get_strbuf(const char *url,
1064                     struct strbuf *result,
1065                     struct http_get_options *options)
1066 {
1067         return http_request_reauth(url, result, HTTP_REQUEST_STRBUF, options);
1068 }
1069
1070 /*
1071  * Downloads a URL and stores the result in the given file.
1072  *
1073  * If a previous interrupted download is detected (i.e. a previous temporary
1074  * file is still around) the download is resumed.
1075  */
1076 static int http_get_file(const char *url, const char *filename,
1077                          struct http_get_options *options)
1078 {
1079         int ret;
1080         struct strbuf tmpfile = STRBUF_INIT;
1081         FILE *result;
1082
1083         strbuf_addf(&tmpfile, "%s.temp", filename);
1084         result = fopen(tmpfile.buf, "a");
1085         if (!result) {
1086                 error("Unable to open local file %s", tmpfile.buf);
1087                 ret = HTTP_ERROR;
1088                 goto cleanup;
1089         }
1090
1091         ret = http_request_reauth(url, result, HTTP_REQUEST_FILE, options);
1092         fclose(result);
1093
1094         if (ret == HTTP_OK && move_temp_to_file(tmpfile.buf, filename))
1095                 ret = HTTP_ERROR;
1096 cleanup:
1097         strbuf_release(&tmpfile);
1098         return ret;
1099 }
1100
1101 int http_fetch_ref(const char *base, struct ref *ref)
1102 {
1103         struct http_get_options options = {0};
1104         char *url;
1105         struct strbuf buffer = STRBUF_INIT;
1106         int ret = -1;
1107
1108         options.no_cache = 1;
1109
1110         url = quote_ref_url(base, ref->name);
1111         if (http_get_strbuf(url, &buffer, &options) == HTTP_OK) {
1112                 strbuf_rtrim(&buffer);
1113                 if (buffer.len == 40)
1114                         ret = get_sha1_hex(buffer.buf, ref->old_sha1);
1115                 else if (starts_with(buffer.buf, "ref: ")) {
1116                         ref->symref = xstrdup(buffer.buf + 5);
1117                         ret = 0;
1118                 }
1119         }
1120
1121         strbuf_release(&buffer);
1122         free(url);
1123         return ret;
1124 }
1125
1126 /* Helpers for fetching packs */
1127 static char *fetch_pack_index(unsigned char *sha1, const char *base_url)
1128 {
1129         char *url, *tmp;
1130         struct strbuf buf = STRBUF_INIT;
1131
1132         if (http_is_verbose)
1133                 fprintf(stderr, "Getting index for pack %s\n", sha1_to_hex(sha1));
1134
1135         end_url_with_slash(&buf, base_url);
1136         strbuf_addf(&buf, "objects/pack/pack-%s.idx", sha1_to_hex(sha1));
1137         url = strbuf_detach(&buf, NULL);
1138
1139         strbuf_addf(&buf, "%s.temp", sha1_pack_index_name(sha1));
1140         tmp = strbuf_detach(&buf, NULL);
1141
1142         if (http_get_file(url, tmp, NULL) != HTTP_OK) {
1143                 error("Unable to get pack index %s", url);
1144                 free(tmp);
1145                 tmp = NULL;
1146         }
1147
1148         free(url);
1149         return tmp;
1150 }
1151
1152 static int fetch_and_setup_pack_index(struct packed_git **packs_head,
1153         unsigned char *sha1, const char *base_url)
1154 {
1155         struct packed_git *new_pack;
1156         char *tmp_idx = NULL;
1157         int ret;
1158
1159         if (has_pack_index(sha1)) {
1160                 new_pack = parse_pack_index(sha1, NULL);
1161                 if (!new_pack)
1162                         return -1; /* parse_pack_index() already issued error message */
1163                 goto add_pack;
1164         }
1165
1166         tmp_idx = fetch_pack_index(sha1, base_url);
1167         if (!tmp_idx)
1168                 return -1;
1169
1170         new_pack = parse_pack_index(sha1, tmp_idx);
1171         if (!new_pack) {
1172                 unlink(tmp_idx);
1173                 free(tmp_idx);
1174
1175                 return -1; /* parse_pack_index() already issued error message */
1176         }
1177
1178         ret = verify_pack_index(new_pack);
1179         if (!ret) {
1180                 close_pack_index(new_pack);
1181                 ret = move_temp_to_file(tmp_idx, sha1_pack_index_name(sha1));
1182         }
1183         free(tmp_idx);
1184         if (ret)
1185                 return -1;
1186
1187 add_pack:
1188         new_pack->next = *packs_head;
1189         *packs_head = new_pack;
1190         return 0;
1191 }
1192
1193 int http_get_info_packs(const char *base_url, struct packed_git **packs_head)
1194 {
1195         struct http_get_options options = {0};
1196         int ret = 0, i = 0;
1197         char *url, *data;
1198         struct strbuf buf = STRBUF_INIT;
1199         unsigned char sha1[20];
1200
1201         end_url_with_slash(&buf, base_url);
1202         strbuf_addstr(&buf, "objects/info/packs");
1203         url = strbuf_detach(&buf, NULL);
1204
1205         options.no_cache = 1;
1206         ret = http_get_strbuf(url, &buf, &options);
1207         if (ret != HTTP_OK)
1208                 goto cleanup;
1209
1210         data = buf.buf;
1211         while (i < buf.len) {
1212                 switch (data[i]) {
1213                 case 'P':
1214                         i++;
1215                         if (i + 52 <= buf.len &&
1216                             starts_with(data + i, " pack-") &&
1217                             starts_with(data + i + 46, ".pack\n")) {
1218                                 get_sha1_hex(data + i + 6, sha1);
1219                                 fetch_and_setup_pack_index(packs_head, sha1,
1220                                                       base_url);
1221                                 i += 51;
1222                                 break;
1223                         }
1224                 default:
1225                         while (i < buf.len && data[i] != '\n')
1226                                 i++;
1227                 }
1228                 i++;
1229         }
1230
1231 cleanup:
1232         free(url);
1233         return ret;
1234 }
1235
1236 void release_http_pack_request(struct http_pack_request *preq)
1237 {
1238         if (preq->packfile != NULL) {
1239                 fclose(preq->packfile);
1240                 preq->packfile = NULL;
1241         }
1242         if (preq->range_header != NULL) {
1243                 curl_slist_free_all(preq->range_header);
1244                 preq->range_header = NULL;
1245         }
1246         preq->slot = NULL;
1247         free(preq->url);
1248 }
1249
1250 int finish_http_pack_request(struct http_pack_request *preq)
1251 {
1252         struct packed_git **lst;
1253         struct packed_git *p = preq->target;
1254         char *tmp_idx;
1255         struct child_process ip;
1256         const char *ip_argv[8];
1257
1258         close_pack_index(p);
1259
1260         fclose(preq->packfile);
1261         preq->packfile = NULL;
1262
1263         lst = preq->lst;
1264         while (*lst != p)
1265                 lst = &((*lst)->next);
1266         *lst = (*lst)->next;
1267
1268         tmp_idx = xstrdup(preq->tmpfile);
1269         strcpy(tmp_idx + strlen(tmp_idx) - strlen(".pack.temp"),
1270                ".idx.temp");
1271
1272         ip_argv[0] = "index-pack";
1273         ip_argv[1] = "-o";
1274         ip_argv[2] = tmp_idx;
1275         ip_argv[3] = preq->tmpfile;
1276         ip_argv[4] = NULL;
1277
1278         memset(&ip, 0, sizeof(ip));
1279         ip.argv = ip_argv;
1280         ip.git_cmd = 1;
1281         ip.no_stdin = 1;
1282         ip.no_stdout = 1;
1283
1284         if (run_command(&ip)) {
1285                 unlink(preq->tmpfile);
1286                 unlink(tmp_idx);
1287                 free(tmp_idx);
1288                 return -1;
1289         }
1290
1291         unlink(sha1_pack_index_name(p->sha1));
1292
1293         if (move_temp_to_file(preq->tmpfile, sha1_pack_name(p->sha1))
1294          || move_temp_to_file(tmp_idx, sha1_pack_index_name(p->sha1))) {
1295                 free(tmp_idx);
1296                 return -1;
1297         }
1298
1299         install_packed_git(p);
1300         free(tmp_idx);
1301         return 0;
1302 }
1303
1304 struct http_pack_request *new_http_pack_request(
1305         struct packed_git *target, const char *base_url)
1306 {
1307         long prev_posn = 0;
1308         char range[RANGE_HEADER_SIZE];
1309         struct strbuf buf = STRBUF_INIT;
1310         struct http_pack_request *preq;
1311
1312         preq = xcalloc(1, sizeof(*preq));
1313         preq->target = target;
1314
1315         end_url_with_slash(&buf, base_url);
1316         strbuf_addf(&buf, "objects/pack/pack-%s.pack",
1317                 sha1_to_hex(target->sha1));
1318         preq->url = strbuf_detach(&buf, NULL);
1319
1320         snprintf(preq->tmpfile, sizeof(preq->tmpfile), "%s.temp",
1321                 sha1_pack_name(target->sha1));
1322         preq->packfile = fopen(preq->tmpfile, "a");
1323         if (!preq->packfile) {
1324                 error("Unable to open local file %s for pack",
1325                       preq->tmpfile);
1326                 goto abort;
1327         }
1328
1329         preq->slot = get_active_slot();
1330         curl_easy_setopt(preq->slot->curl, CURLOPT_FILE, preq->packfile);
1331         curl_easy_setopt(preq->slot->curl, CURLOPT_WRITEFUNCTION, fwrite);
1332         curl_easy_setopt(preq->slot->curl, CURLOPT_URL, preq->url);
1333         curl_easy_setopt(preq->slot->curl, CURLOPT_HTTPHEADER,
1334                 no_pragma_header);
1335
1336         /*
1337          * If there is data present from a previous transfer attempt,
1338          * resume where it left off
1339          */
1340         prev_posn = ftell(preq->packfile);
1341         if (prev_posn>0) {
1342                 if (http_is_verbose)
1343                         fprintf(stderr,
1344                                 "Resuming fetch of pack %s at byte %ld\n",
1345                                 sha1_to_hex(target->sha1), prev_posn);
1346                 sprintf(range, "Range: bytes=%ld-", prev_posn);
1347                 preq->range_header = curl_slist_append(NULL, range);
1348                 curl_easy_setopt(preq->slot->curl, CURLOPT_HTTPHEADER,
1349                         preq->range_header);
1350         }
1351
1352         return preq;
1353
1354 abort:
1355         free(preq->url);
1356         free(preq);
1357         return NULL;
1358 }
1359
1360 /* Helpers for fetching objects (loose) */
1361 static size_t fwrite_sha1_file(char *ptr, size_t eltsize, size_t nmemb,
1362                                void *data)
1363 {
1364         unsigned char expn[4096];
1365         size_t size = eltsize * nmemb;
1366         int posn = 0;
1367         struct http_object_request *freq =
1368                 (struct http_object_request *)data;
1369         do {
1370                 ssize_t retval = xwrite(freq->localfile,
1371                                         (char *) ptr + posn, size - posn);
1372                 if (retval < 0)
1373                         return posn;
1374                 posn += retval;
1375         } while (posn < size);
1376
1377         freq->stream.avail_in = size;
1378         freq->stream.next_in = (void *)ptr;
1379         do {
1380                 freq->stream.next_out = expn;
1381                 freq->stream.avail_out = sizeof(expn);
1382                 freq->zret = git_inflate(&freq->stream, Z_SYNC_FLUSH);
1383                 git_SHA1_Update(&freq->c, expn,
1384                                 sizeof(expn) - freq->stream.avail_out);
1385         } while (freq->stream.avail_in && freq->zret == Z_OK);
1386         return size;
1387 }
1388
1389 struct http_object_request *new_http_object_request(const char *base_url,
1390         unsigned char *sha1)
1391 {
1392         char *hex = sha1_to_hex(sha1);
1393         const char *filename;
1394         char prevfile[PATH_MAX];
1395         int prevlocal;
1396         char prev_buf[PREV_BUF_SIZE];
1397         ssize_t prev_read = 0;
1398         long prev_posn = 0;
1399         char range[RANGE_HEADER_SIZE];
1400         struct curl_slist *range_header = NULL;
1401         struct http_object_request *freq;
1402
1403         freq = xcalloc(1, sizeof(*freq));
1404         hashcpy(freq->sha1, sha1);
1405         freq->localfile = -1;
1406
1407         filename = sha1_file_name(sha1);
1408         snprintf(freq->tmpfile, sizeof(freq->tmpfile),
1409                  "%s.temp", filename);
1410
1411         snprintf(prevfile, sizeof(prevfile), "%s.prev", filename);
1412         unlink_or_warn(prevfile);
1413         rename(freq->tmpfile, prevfile);
1414         unlink_or_warn(freq->tmpfile);
1415
1416         if (freq->localfile != -1)
1417                 error("fd leakage in start: %d", freq->localfile);
1418         freq->localfile = open(freq->tmpfile,
1419                                O_WRONLY | O_CREAT | O_EXCL, 0666);
1420         /*
1421          * This could have failed due to the "lazy directory creation";
1422          * try to mkdir the last path component.
1423          */
1424         if (freq->localfile < 0 && errno == ENOENT) {
1425                 char *dir = strrchr(freq->tmpfile, '/');
1426                 if (dir) {
1427                         *dir = 0;
1428                         mkdir(freq->tmpfile, 0777);
1429                         *dir = '/';
1430                 }
1431                 freq->localfile = open(freq->tmpfile,
1432                                        O_WRONLY | O_CREAT | O_EXCL, 0666);
1433         }
1434
1435         if (freq->localfile < 0) {
1436                 error("Couldn't create temporary file %s: %s",
1437                       freq->tmpfile, strerror(errno));
1438                 goto abort;
1439         }
1440
1441         git_inflate_init(&freq->stream);
1442
1443         git_SHA1_Init(&freq->c);
1444
1445         freq->url = get_remote_object_url(base_url, hex, 0);
1446
1447         /*
1448          * If a previous temp file is present, process what was already
1449          * fetched.
1450          */
1451         prevlocal = open(prevfile, O_RDONLY);
1452         if (prevlocal != -1) {
1453                 do {
1454                         prev_read = xread(prevlocal, prev_buf, PREV_BUF_SIZE);
1455                         if (prev_read>0) {
1456                                 if (fwrite_sha1_file(prev_buf,
1457                                                      1,
1458                                                      prev_read,
1459                                                      freq) == prev_read) {
1460                                         prev_posn += prev_read;
1461                                 } else {
1462                                         prev_read = -1;
1463                                 }
1464                         }
1465                 } while (prev_read > 0);
1466                 close(prevlocal);
1467         }
1468         unlink_or_warn(prevfile);
1469
1470         /*
1471          * Reset inflate/SHA1 if there was an error reading the previous temp
1472          * file; also rewind to the beginning of the local file.
1473          */
1474         if (prev_read == -1) {
1475                 memset(&freq->stream, 0, sizeof(freq->stream));
1476                 git_inflate_init(&freq->stream);
1477                 git_SHA1_Init(&freq->c);
1478                 if (prev_posn>0) {
1479                         prev_posn = 0;
1480                         lseek(freq->localfile, 0, SEEK_SET);
1481                         if (ftruncate(freq->localfile, 0) < 0) {
1482                                 error("Couldn't truncate temporary file %s: %s",
1483                                           freq->tmpfile, strerror(errno));
1484                                 goto abort;
1485                         }
1486                 }
1487         }
1488
1489         freq->slot = get_active_slot();
1490
1491         curl_easy_setopt(freq->slot->curl, CURLOPT_FILE, freq);
1492         curl_easy_setopt(freq->slot->curl, CURLOPT_WRITEFUNCTION, fwrite_sha1_file);
1493         curl_easy_setopt(freq->slot->curl, CURLOPT_ERRORBUFFER, freq->errorstr);
1494         curl_easy_setopt(freq->slot->curl, CURLOPT_URL, freq->url);
1495         curl_easy_setopt(freq->slot->curl, CURLOPT_HTTPHEADER, no_pragma_header);
1496
1497         /*
1498          * If we have successfully processed data from a previous fetch
1499          * attempt, only fetch the data we don't already have.
1500          */
1501         if (prev_posn>0) {
1502                 if (http_is_verbose)
1503                         fprintf(stderr,
1504                                 "Resuming fetch of object %s at byte %ld\n",
1505                                 hex, prev_posn);
1506                 sprintf(range, "Range: bytes=%ld-", prev_posn);
1507                 range_header = curl_slist_append(range_header, range);
1508                 curl_easy_setopt(freq->slot->curl,
1509                                  CURLOPT_HTTPHEADER, range_header);
1510         }
1511
1512         return freq;
1513
1514 abort:
1515         free(freq->url);
1516         free(freq);
1517         return NULL;
1518 }
1519
1520 void process_http_object_request(struct http_object_request *freq)
1521 {
1522         if (freq->slot == NULL)
1523                 return;
1524         freq->curl_result = freq->slot->curl_result;
1525         freq->http_code = freq->slot->http_code;
1526         freq->slot = NULL;
1527 }
1528
1529 int finish_http_object_request(struct http_object_request *freq)
1530 {
1531         struct stat st;
1532
1533         close(freq->localfile);
1534         freq->localfile = -1;
1535
1536         process_http_object_request(freq);
1537
1538         if (freq->http_code == 416) {
1539                 warning("requested range invalid; we may already have all the data.");
1540         } else if (freq->curl_result != CURLE_OK) {
1541                 if (stat(freq->tmpfile, &st) == 0)
1542                         if (st.st_size == 0)
1543                                 unlink_or_warn(freq->tmpfile);
1544                 return -1;
1545         }
1546
1547         git_inflate_end(&freq->stream);
1548         git_SHA1_Final(freq->real_sha1, &freq->c);
1549         if (freq->zret != Z_STREAM_END) {
1550                 unlink_or_warn(freq->tmpfile);
1551                 return -1;
1552         }
1553         if (hashcmp(freq->sha1, freq->real_sha1)) {
1554                 unlink_or_warn(freq->tmpfile);
1555                 return -1;
1556         }
1557         freq->rename =
1558                 move_temp_to_file(freq->tmpfile, sha1_file_name(freq->sha1));
1559
1560         return freq->rename;
1561 }
1562
1563 void abort_http_object_request(struct http_object_request *freq)
1564 {
1565         unlink_or_warn(freq->tmpfile);
1566
1567         release_http_object_request(freq);
1568 }
1569
1570 void release_http_object_request(struct http_object_request *freq)
1571 {
1572         if (freq->localfile != -1) {
1573                 close(freq->localfile);
1574                 freq->localfile = -1;
1575         }
1576         if (freq->url != NULL) {
1577                 free(freq->url);
1578                 freq->url = NULL;
1579         }
1580         if (freq->slot != NULL) {
1581                 freq->slot->callback_func = NULL;
1582                 freq->slot->callback_data = NULL;
1583                 release_active_slot(freq->slot);
1584                 freq->slot = NULL;
1585         }
1586 }