Andrew's git / gitweb.git / http-walker.c
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http-walker.con commit log_ref_setup(): improve robustness against races (1fb0c80)
   1#include "cache.h"
   2#include "commit.h"
   3#include "walker.h"
   4#include "http.h"
   5#include "list.h"
   6#include "transport.h"
   7
   8struct alt_base {
   9        char *base;
  10        int got_indices;
  11        struct packed_git *packs;
  12        struct alt_base *next;
  13};
  14
  15enum object_request_state {
  16        WAITING,
  17        ABORTED,
  18        ACTIVE,
  19        COMPLETE
  20};
  21
  22struct object_request {
  23        struct walker *walker;
  24        unsigned char sha1[20];
  25        struct alt_base *repo;
  26        enum object_request_state state;
  27        struct http_object_request *req;
  28        struct list_head node;
  29};
  30
  31struct alternates_request {
  32        struct walker *walker;
  33        const char *base;
  34        struct strbuf *url;
  35        struct strbuf *buffer;
  36        struct active_request_slot *slot;
  37        int http_specific;
  38};
  39
  40struct walker_data {
  41        const char *url;
  42        int got_alternates;
  43        struct alt_base *alt;
  44};
  45
  46static LIST_HEAD(object_queue_head);
  47
  48static void fetch_alternates(struct walker *walker, const char *base);
  49
  50static void process_object_response(void *callback_data);
  51
  52static void start_object_request(struct walker *walker,
  53                                 struct object_request *obj_req)
  54{
  55        struct active_request_slot *slot;
  56        struct http_object_request *req;
  57
  58        req = new_http_object_request(obj_req->repo->base, obj_req->sha1);
  59        if (req == NULL) {
  60                obj_req->state = ABORTED;
  61                return;
  62        }
  63        obj_req->req = req;
  64
  65        slot = req->slot;
  66        slot->callback_func = process_object_response;
  67        slot->callback_data = obj_req;
  68
  69        /* Try to get the request started, abort the request on error */
  70        obj_req->state = ACTIVE;
  71        if (!start_active_slot(slot)) {
  72                obj_req->state = ABORTED;
  73                release_http_object_request(req);
  74                return;
  75        }
  76}
  77
  78static void finish_object_request(struct object_request *obj_req)
  79{
  80        if (finish_http_object_request(obj_req->req))
  81                return;
  82
  83        if (obj_req->req->rename == 0)
  84                walker_say(obj_req->walker, "got %s\n", sha1_to_hex(obj_req->sha1));
  85}
  86
  87static void process_object_response(void *callback_data)
  88{
  89        struct object_request *obj_req =
  90                (struct object_request *)callback_data;
  91        struct walker *walker = obj_req->walker;
  92        struct walker_data *data = walker->data;
  93        struct alt_base *alt = data->alt;
  94
  95        process_http_object_request(obj_req->req);
  96        obj_req->state = COMPLETE;
  97
  98        /* Use alternates if necessary */
  99        if (missing_target(obj_req->req)) {
 100                fetch_alternates(walker, alt->base);
 101                if (obj_req->repo->next != NULL) {
 102                        obj_req->repo =
 103                                obj_req->repo->next;
 104                        release_http_object_request(obj_req->req);
 105                        start_object_request(walker, obj_req);
 106                        return;
 107                }
 108        }
 109
 110        finish_object_request(obj_req);
 111}
 112
 113static void release_object_request(struct object_request *obj_req)
 114{
 115        if (obj_req->req !=NULL && obj_req->req->localfile != -1)
 116                error("fd leakage in release: %d", obj_req->req->localfile);
 117
 118        list_del(&obj_req->node);
 119        free(obj_req);
 120}
 121
 122#ifdef USE_CURL_MULTI
 123static int fill_active_slot(struct walker *walker)
 124{
 125        struct object_request *obj_req;
 126        struct list_head *pos, *tmp, *head = &object_queue_head;
 127
 128        list_for_each_safe(pos, tmp, head) {
 129                obj_req = list_entry(pos, struct object_request, node);
 130                if (obj_req->state == WAITING) {
 131                        if (has_sha1_file(obj_req->sha1))
 132                                obj_req->state = COMPLETE;
 133                        else {
 134                                start_object_request(walker, obj_req);
 135                                return 1;
 136                        }
 137                }
 138        }
 139        return 0;
 140}
 141#endif
 142
 143static void prefetch(struct walker *walker, unsigned char *sha1)
 144{
 145        struct object_request *newreq;
 146        struct walker_data *data = walker->data;
 147
 148        newreq = xmalloc(sizeof(*newreq));
 149        newreq->walker = walker;
 150        hashcpy(newreq->sha1, sha1);
 151        newreq->repo = data->alt;
 152        newreq->state = WAITING;
 153        newreq->req = NULL;
 154
 155        http_is_verbose = walker->get_verbosely;
 156        list_add_tail(&newreq->node, &object_queue_head);
 157
 158#ifdef USE_CURL_MULTI
 159        fill_active_slots();
 160        step_active_slots();
 161#endif
 162}
 163
 164static int is_alternate_allowed(const char *url)
 165{
 166        const char *protocols[] = {
 167                "http", "https", "ftp", "ftps"
 168        };
 169        int i;
 170
 171        for (i = 0; i < ARRAY_SIZE(protocols); i++) {
 172                const char *end;
 173                if (skip_prefix(url, protocols[i], &end) &&
 174                    starts_with(end, "://"))
 175                        break;
 176        }
 177
 178        if (i >= ARRAY_SIZE(protocols)) {
 179                warning("ignoring alternate with unknown protocol: %s", url);
 180                return 0;
 181        }
 182        if (!is_transport_allowed(protocols[i], 0)) {
 183                warning("ignoring alternate with restricted protocol: %s", url);
 184                return 0;
 185        }
 186
 187        return 1;
 188}
 189
 190static void process_alternates_response(void *callback_data)
 191{
 192        struct alternates_request *alt_req =
 193                (struct alternates_request *)callback_data;
 194        struct walker *walker = alt_req->walker;
 195        struct walker_data *cdata = walker->data;
 196        struct active_request_slot *slot = alt_req->slot;
 197        struct alt_base *tail = cdata->alt;
 198        const char *base = alt_req->base;
 199        const char null_byte = '\0';
 200        char *data;
 201        int i = 0;
 202
 203        if (alt_req->http_specific) {
 204                if (slot->curl_result != CURLE_OK ||
 205                    !alt_req->buffer->len) {
 206
 207                        /* Try reusing the slot to get non-http alternates */
 208                        alt_req->http_specific = 0;
 209                        strbuf_reset(alt_req->url);
 210                        strbuf_addf(alt_req->url, "%s/objects/info/alternates",
 211                                    base);
 212                        curl_easy_setopt(slot->curl, CURLOPT_URL,
 213                                         alt_req->url->buf);
 214                        active_requests++;
 215                        slot->in_use = 1;
 216                        if (slot->finished != NULL)
 217                                (*slot->finished) = 0;
 218                        if (!start_active_slot(slot)) {
 219                                cdata->got_alternates = -1;
 220                                slot->in_use = 0;
 221                                if (slot->finished != NULL)
 222                                        (*slot->finished) = 1;
 223                        }
 224                        return;
 225                }
 226        } else if (slot->curl_result != CURLE_OK) {
 227                if (!missing_target(slot)) {
 228                        cdata->got_alternates = -1;
 229                        return;
 230                }
 231        }
 232
 233        fwrite_buffer((char *)&null_byte, 1, 1, alt_req->buffer);
 234        alt_req->buffer->len--;
 235        data = alt_req->buffer->buf;
 236
 237        while (i < alt_req->buffer->len) {
 238                int posn = i;
 239                while (posn < alt_req->buffer->len && data[posn] != '\n')
 240                        posn++;
 241                if (data[posn] == '\n') {
 242                        int okay = 0;
 243                        int serverlen = 0;
 244                        struct alt_base *newalt;
 245                        if (data[i] == '/') {
 246                                /*
 247                                 * This counts
 248                                 * http://git.host/pub/scm/linux.git/
 249                                 * -----------here^
 250                                 * so memcpy(dst, base, serverlen) will
 251                                 * copy up to "...git.host".
 252                                 */
 253                                const char *colon_ss = strstr(base,"://");
 254                                if (colon_ss) {
 255                                        serverlen = (strchr(colon_ss + 3, '/')
 256                                                     - base);
 257                                        okay = 1;
 258                                }
 259                        } else if (!memcmp(data + i, "../", 3)) {
 260                                /*
 261                                 * Relative URL; chop the corresponding
 262                                 * number of subpath from base (and ../
 263                                 * from data), and concatenate the result.
 264                                 *
 265                                 * The code first drops ../ from data, and
 266                                 * then drops one ../ from data and one path
 267                                 * from base.  IOW, one extra ../ is dropped
 268                                 * from data than path is dropped from base.
 269                                 *
 270                                 * This is not wrong.  The alternate in
 271                                 *     http://git.host/pub/scm/linux.git/
 272                                 * to borrow from
 273                                 *     http://git.host/pub/scm/linus.git/
 274                                 * is ../../linus.git/objects/.  You need
 275                                 * two ../../ to borrow from your direct
 276                                 * neighbour.
 277                                 */
 278                                i += 3;
 279                                serverlen = strlen(base);
 280                                while (i + 2 < posn &&
 281                                       !memcmp(data + i, "../", 3)) {
 282                                        do {
 283                                                serverlen--;
 284                                        } while (serverlen &&
 285                                                 base[serverlen - 1] != '/');
 286                                        i += 3;
 287                                }
 288                                /* If the server got removed, give up. */
 289                                okay = strchr(base, ':') - base + 3 <
 290                                       serverlen;
 291                        } else if (alt_req->http_specific) {
 292                                char *colon = strchr(data + i, ':');
 293                                char *slash = strchr(data + i, '/');
 294                                if (colon && slash && colon < data + posn &&
 295                                    slash < data + posn && colon < slash) {
 296                                        okay = 1;
 297                                }
 298                        }
 299                        /* skip "objects\n" at end */
 300                        if (okay) {
 301                                struct strbuf target = STRBUF_INIT;
 302                                strbuf_add(&target, base, serverlen);
 303                                strbuf_add(&target, data + i, posn - i - 7);
 304
 305                                if (is_alternate_allowed(target.buf)) {
 306                                        warning("adding alternate object store: %s",
 307                                                target.buf);
 308                                        newalt = xmalloc(sizeof(*newalt));
 309                                        newalt->next = NULL;
 310                                        newalt->base = strbuf_detach(&target, NULL);
 311                                        newalt->got_indices = 0;
 312                                        newalt->packs = NULL;
 313
 314                                        while (tail->next != NULL)
 315                                                tail = tail->next;
 316                                        tail->next = newalt;
 317                                }
 318                        }
 319                }
 320                i = posn + 1;
 321        }
 322
 323        cdata->got_alternates = 1;
 324}
 325
 326static void fetch_alternates(struct walker *walker, const char *base)
 327{
 328        struct strbuf buffer = STRBUF_INIT;
 329        struct strbuf url = STRBUF_INIT;
 330        struct active_request_slot *slot;
 331        struct alternates_request alt_req;
 332        struct walker_data *cdata = walker->data;
 333
 334        if (http_follow_config != HTTP_FOLLOW_ALWAYS)
 335                return;
 336
 337        /*
 338         * If another request has already started fetching alternates,
 339         * wait for them to arrive and return to processing this request's
 340         * curl message
 341         */
 342#ifdef USE_CURL_MULTI
 343        while (cdata->got_alternates == 0) {
 344                step_active_slots();
 345        }
 346#endif
 347
 348        /* Nothing to do if they've already been fetched */
 349        if (cdata->got_alternates == 1)
 350                return;
 351
 352        /* Start the fetch */
 353        cdata->got_alternates = 0;
 354
 355        if (walker->get_verbosely)
 356                fprintf(stderr, "Getting alternates list for %s\n", base);
 357
 358        strbuf_addf(&url, "%s/objects/info/http-alternates", base);
 359
 360        /*
 361         * Use a callback to process the result, since another request
 362         * may fail and need to have alternates loaded before continuing
 363         */
 364        slot = get_active_slot();
 365        slot->callback_func = process_alternates_response;
 366        alt_req.walker = walker;
 367        slot->callback_data = &alt_req;
 368
 369        curl_easy_setopt(slot->curl, CURLOPT_FILE, &buffer);
 370        curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite_buffer);
 371        curl_easy_setopt(slot->curl, CURLOPT_URL, url.buf);
 372
 373        alt_req.base = base;
 374        alt_req.url = &url;
 375        alt_req.buffer = &buffer;
 376        alt_req.http_specific = 1;
 377        alt_req.slot = slot;
 378
 379        if (start_active_slot(slot))
 380                run_active_slot(slot);
 381        else
 382                cdata->got_alternates = -1;
 383
 384        strbuf_release(&buffer);
 385        strbuf_release(&url);
 386}
 387
 388static int fetch_indices(struct walker *walker, struct alt_base *repo)
 389{
 390        int ret;
 391
 392        if (repo->got_indices)
 393                return 0;
 394
 395        if (walker->get_verbosely)
 396                fprintf(stderr, "Getting pack list for %s\n", repo->base);
 397
 398        switch (http_get_info_packs(repo->base, &repo->packs)) {
 399        case HTTP_OK:
 400        case HTTP_MISSING_TARGET:
 401                repo->got_indices = 1;
 402                ret = 0;
 403                break;
 404        default:
 405                repo->got_indices = 0;
 406                ret = -1;
 407        }
 408
 409        return ret;
 410}
 411
 412static int http_fetch_pack(struct walker *walker, struct alt_base *repo, unsigned char *sha1)
 413{
 414        struct packed_git *target;
 415        int ret;
 416        struct slot_results results;
 417        struct http_pack_request *preq;
 418
 419        if (fetch_indices(walker, repo))
 420                return -1;
 421        target = find_sha1_pack(sha1, repo->packs);
 422        if (!target)
 423                return -1;
 424
 425        if (walker->get_verbosely) {
 426                fprintf(stderr, "Getting pack %s\n",
 427                        sha1_to_hex(target->sha1));
 428                fprintf(stderr, " which contains %s\n",
 429                        sha1_to_hex(sha1));
 430        }
 431
 432        preq = new_http_pack_request(target, repo->base);
 433        if (preq == NULL)
 434                goto abort;
 435        preq->lst = &repo->packs;
 436        preq->slot->results = &results;
 437
 438        if (start_active_slot(preq->slot)) {
 439                run_active_slot(preq->slot);
 440                if (results.curl_result != CURLE_OK) {
 441                        error("Unable to get pack file %s\n%s", preq->url,
 442                              curl_errorstr);
 443                        goto abort;
 444                }
 445        } else {
 446                error("Unable to start request");
 447                goto abort;
 448        }
 449
 450        ret = finish_http_pack_request(preq);
 451        release_http_pack_request(preq);
 452        if (ret)
 453                return ret;
 454
 455        return 0;
 456
 457abort:
 458        return -1;
 459}
 460
 461static void abort_object_request(struct object_request *obj_req)
 462{
 463        release_object_request(obj_req);
 464}
 465
 466static int fetch_object(struct walker *walker, unsigned char *sha1)
 467{
 468        char *hex = sha1_to_hex(sha1);
 469        int ret = 0;
 470        struct object_request *obj_req = NULL;
 471        struct http_object_request *req;
 472        struct list_head *pos, *head = &object_queue_head;
 473
 474        list_for_each(pos, head) {
 475                obj_req = list_entry(pos, struct object_request, node);
 476                if (!hashcmp(obj_req->sha1, sha1))
 477                        break;
 478        }
 479        if (obj_req == NULL)
 480                return error("Couldn't find request for %s in the queue", hex);
 481
 482        if (has_sha1_file(obj_req->sha1)) {
 483                if (obj_req->req != NULL)
 484                        abort_http_object_request(obj_req->req);
 485                abort_object_request(obj_req);
 486                return 0;
 487        }
 488
 489#ifdef USE_CURL_MULTI
 490        while (obj_req->state == WAITING)
 491                step_active_slots();
 492#else
 493        start_object_request(walker, obj_req);
 494#endif
 495
 496        /*
 497         * obj_req->req might change when fetching alternates in the callback
 498         * process_object_response; therefore, the "shortcut" variable, req,
 499         * is used only after we're done with slots.
 500         */
 501        while (obj_req->state == ACTIVE)
 502                run_active_slot(obj_req->req->slot);
 503
 504        req = obj_req->req;
 505
 506        if (req->localfile != -1) {
 507                close(req->localfile);
 508                req->localfile = -1;
 509        }
 510
 511        /*
 512         * we turned off CURLOPT_FAILONERROR to avoid losing a
 513         * persistent connection and got CURLE_OK.
 514         */
 515        if (req->http_code >= 300 && req->curl_result == CURLE_OK &&
 516                        (starts_with(req->url, "http://") ||
 517                         starts_with(req->url, "https://"))) {
 518                req->curl_result = CURLE_HTTP_RETURNED_ERROR;
 519                xsnprintf(req->errorstr, sizeof(req->errorstr),
 520                          "HTTP request failed");
 521        }
 522
 523        if (obj_req->state == ABORTED) {
 524                ret = error("Request for %s aborted", hex);
 525        } else if (req->curl_result != CURLE_OK &&
 526                   req->http_code != 416) {
 527                if (missing_target(req))
 528                        ret = -1; /* Be silent, it is probably in a pack. */
 529                else
 530                        ret = error("%s (curl_result = %d, http_code = %ld, sha1 = %s)",
 531                                    req->errorstr, req->curl_result,
 532                                    req->http_code, hex);
 533        } else if (req->zret != Z_STREAM_END) {
 534                walker->corrupt_object_found++;
 535                ret = error("File %s (%s) corrupt", hex, req->url);
 536        } else if (hashcmp(obj_req->sha1, req->real_sha1)) {
 537                ret = error("File %s has bad hash", hex);
 538        } else if (req->rename < 0) {
 539                ret = error("unable to write sha1 filename %s",
 540                            sha1_file_name(req->sha1));
 541        }
 542
 543        release_http_object_request(req);
 544        release_object_request(obj_req);
 545        return ret;
 546}
 547
 548static int fetch(struct walker *walker, unsigned char *sha1)
 549{
 550        struct walker_data *data = walker->data;
 551        struct alt_base *altbase = data->alt;
 552
 553        if (!fetch_object(walker, sha1))
 554                return 0;
 555        while (altbase) {
 556                if (!http_fetch_pack(walker, altbase, sha1))
 557                        return 0;
 558                fetch_alternates(walker, data->alt->base);
 559                altbase = altbase->next;
 560        }
 561        return error("Unable to find %s under %s", sha1_to_hex(sha1),
 562                     data->alt->base);
 563}
 564
 565static int fetch_ref(struct walker *walker, struct ref *ref)
 566{
 567        struct walker_data *data = walker->data;
 568        return http_fetch_ref(data->alt->base, ref);
 569}
 570
 571static void cleanup(struct walker *walker)
 572{
 573        struct walker_data *data = walker->data;
 574        struct alt_base *alt, *alt_next;
 575
 576        if (data) {
 577                alt = data->alt;
 578                while (alt) {
 579                        alt_next = alt->next;
 580
 581                        free(alt->base);
 582                        free(alt);
 583
 584                        alt = alt_next;
 585                }
 586                free(data);
 587                walker->data = NULL;
 588        }
 589}
 590
 591struct walker *get_http_walker(const char *url)
 592{
 593        char *s;
 594        struct walker_data *data = xmalloc(sizeof(struct walker_data));
 595        struct walker *walker = xmalloc(sizeof(struct walker));
 596
 597        data->alt = xmalloc(sizeof(*data->alt));
 598        data->alt->base = xstrdup(url);
 599        for (s = data->alt->base + strlen(data->alt->base) - 1; *s == '/'; --s)
 600                *s = 0;
 601
 602        data->alt->got_indices = 0;
 603        data->alt->packs = NULL;
 604        data->alt->next = NULL;
 605        data->got_alternates = -1;
 606
 607        walker->corrupt_object_found = 0;
 608        walker->fetch = fetch;
 609        walker->fetch_ref = fetch_ref;
 610        walker->prefetch = prefetch;
 611        walker->cleanup = cleanup;
 612        walker->data = data;
 613
 614#ifdef USE_CURL_MULTI
 615        add_fill_function(walker, (int (*)(void *)) fill_active_slot);
 616#endif
 617
 618        return walker;
 619}