Documentation: add Packfile URIs design doc

[git.git] / remote-curl.c

#include "cache.h"
#include "config.h"
#include "remote.h"
#include "connect.h"
#include "strbuf.h"
#include "walker.h"
#include "http.h"
#include "exec-cmd.h"
#include "run-command.h"
#include "pkt-line.h"
#include "string-list.h"
#include "sideband.h"
#include "argv-array.h"
#include "credential.h"
#include "oid-array.h"
#include "send-pack.h"
#include "protocol.h"
#include "quote.h"
#include "transport.h"

static struct remote *remote;
/* always ends with a trailing slash */
static struct strbuf url = STRBUF_INIT;

struct options {
        int verbosity;
        unsigned long depth;
        char *deepen_since;
        struct string_list deepen_not;
        struct string_list push_options;
        char *filter;
        unsigned progress : 1,
                check_self_contained_and_connected : 1,
                cloning : 1,
                update_shallow : 1,
                followtags : 1,
                dry_run : 1,
                thin : 1,
                /* One of the SEND_PACK_PUSH_CERT_* constants. */
                push_cert : 2,
                deepen_relative : 1,
                from_promisor : 1,
                no_dependents : 1,
                atomic : 1;
};
static struct options options;
static struct string_list cas_options = STRING_LIST_INIT_DUP;

static int set_option(const char *name, const char *value)
{
        if (!strcmp(name, "verbosity")) {
                char *end;
                int v = strtol(value, &end, 10);
                if (value == end || *end)
                        return -1;
                options.verbosity = v;
                return 0;
        }
        else if (!strcmp(name, "progress")) {
                if (!strcmp(value, "true"))
                        options.progress = 1;
                else if (!strcmp(value, "false"))
                        options.progress = 0;
                else
                        return -1;
                return 0;
        }
        else if (!strcmp(name, "depth")) {
                char *end;
                unsigned long v = strtoul(value, &end, 10);
                if (value == end || *end)
                        return -1;
                options.depth = v;
                return 0;
        }
        else if (!strcmp(name, "deepen-since")) {
                options.deepen_since = xstrdup(value);
                return 0;
        }
        else if (!strcmp(name, "deepen-not")) {
                string_list_append(&options.deepen_not, value);
                return 0;
        }
        else if (!strcmp(name, "deepen-relative")) {
                if (!strcmp(value, "true"))
                        options.deepen_relative = 1;
                else if (!strcmp(value, "false"))
                        options.deepen_relative = 0;
                else
                        return -1;
                return 0;
        }
        else if (!strcmp(name, "followtags")) {
                if (!strcmp(value, "true"))
                        options.followtags = 1;
                else if (!strcmp(value, "false"))
                        options.followtags = 0;
                else
                        return -1;
                return 0;
        }
        else if (!strcmp(name, "dry-run")) {
                if (!strcmp(value, "true"))
                        options.dry_run = 1;
                else if (!strcmp(value, "false"))
                        options.dry_run = 0;
                else
                        return -1;
                return 0;
        }
        else if (!strcmp(name, "check-connectivity")) {
                if (!strcmp(value, "true"))
                        options.check_self_contained_and_connected = 1;
                else if (!strcmp(value, "false"))
                        options.check_self_contained_and_connected = 0;
                else
                        return -1;
                return 0;
        }
        else if (!strcmp(name, "cas")) {
                struct strbuf val = STRBUF_INIT;
                strbuf_addf(&val, "--" CAS_OPT_NAME "=%s", value);
                string_list_append(&cas_options, val.buf);
                strbuf_release(&val);
                return 0;
        } else if (!strcmp(name, "cloning")) {
                if (!strcmp(value, "true"))
                        options.cloning = 1;
                else if (!strcmp(value, "false"))
                        options.cloning = 0;
                else
                        return -1;
                return 0;
        } else if (!strcmp(name, "update-shallow")) {
                if (!strcmp(value, "true"))
                        options.update_shallow = 1;
                else if (!strcmp(value, "false"))
                        options.update_shallow = 0;
                else
                        return -1;
                return 0;
        } else if (!strcmp(name, "pushcert")) {
                if (!strcmp(value, "true"))
                        options.push_cert = SEND_PACK_PUSH_CERT_ALWAYS;
                else if (!strcmp(value, "false"))
                        options.push_cert = SEND_PACK_PUSH_CERT_NEVER;
                else if (!strcmp(value, "if-asked"))
                        options.push_cert = SEND_PACK_PUSH_CERT_IF_ASKED;
                else
                        return -1;
                return 0;
        } else if (!strcmp(name, "atomic")) {
                if (!strcmp(value, "true"))
                        options.atomic = 1;
                else if (!strcmp(value, "false"))
                        options.atomic = 0;
                else
                        return -1;
                return 0;
        } else if (!strcmp(name, "push-option")) {
                if (*value != '"')
                        string_list_append(&options.push_options, value);
                else {
                        struct strbuf unquoted = STRBUF_INIT;
                        if (unquote_c_style(&unquoted, value, NULL) < 0)
                                die(_("invalid quoting in push-option value: '%s'"), value);
                        string_list_append_nodup(&options.push_options,
                                                 strbuf_detach(&unquoted, NULL));
                }
                return 0;

#if LIBCURL_VERSION_NUM >= 0x070a08
        } else if (!strcmp(name, "family")) {
                if (!strcmp(value, "ipv4"))
                        git_curl_ipresolve = CURL_IPRESOLVE_V4;
                else if (!strcmp(value, "ipv6"))
                        git_curl_ipresolve = CURL_IPRESOLVE_V6;
                else if (!strcmp(value, "all"))
                        git_curl_ipresolve = CURL_IPRESOLVE_WHATEVER;
                else
                        return -1;
                return 0;
#endif /* LIBCURL_VERSION_NUM >= 0x070a08 */
        } else if (!strcmp(name, "from-promisor")) {
                options.from_promisor = 1;
                return 0;
        } else if (!strcmp(name, "no-dependents")) {
                options.no_dependents = 1;
                return 0;
        } else if (!strcmp(name, "filter")) {
                options.filter = xstrdup(value);
                return 0;
        } else {
                return 1 /* unsupported */;
        }
}

struct discovery {
        char *service;
        char *buf_alloc;
        char *buf;
        size_t len;
        struct ref *refs;
        struct oid_array shallow;
        enum protocol_version version;
        unsigned proto_git : 1;
};
static struct discovery *last_discovery;

static struct ref *parse_git_refs(struct discovery *heads, int for_push)
{
        struct ref *list = NULL;
        struct packet_reader reader;

        packet_reader_init(&reader, -1, heads->buf, heads->len,
                           PACKET_READ_CHOMP_NEWLINE |
                           PACKET_READ_GENTLE_ON_EOF |
                           PACKET_READ_DIE_ON_ERR_PACKET);

        heads->version = discover_version(&reader);
        switch (heads->version) {
        case protocol_v2:
                /*
                 * Do nothing.  This isn't a list of refs but rather a
                 * capability advertisement.  Client would have run
                 * 'stateless-connect' so we'll dump this capability listing
                 * and let them request the refs themselves.
                 */
                break;
        case protocol_v1:
        case protocol_v0:
                get_remote_heads(&reader, &list, for_push ? REF_NORMAL : 0,
                                 NULL, &heads->shallow);
                break;
        case protocol_unknown_version:
                BUG("unknown protocol version");
        }

        return list;
}

static struct ref *parse_info_refs(struct discovery *heads)
{
        char *data, *start, *mid;
        char *ref_name;
        int i = 0;

        struct ref *refs = NULL;
        struct ref *ref = NULL;
        struct ref *last_ref = NULL;

        data = heads->buf;
        start = NULL;
        mid = data;
        while (i < heads->len) {
                if (!start) {
                        start = &data[i];
                }
                if (data[i] == '\t')
                        mid = &data[i];
                if (data[i] == '\n') {
                        if (mid - start != the_hash_algo->hexsz)
                                die(_("%sinfo/refs not valid: is this a git repository?"),
                                    transport_anonymize_url(url.buf));
                        data[i] = 0;
                        ref_name = mid + 1;
                        ref = alloc_ref(ref_name);
                        get_oid_hex(start, &ref->old_oid);
                        if (!refs)
                                refs = ref;
                        if (last_ref)
                                last_ref->next = ref;
                        last_ref = ref;
                        start = NULL;
                }
                i++;
        }

        ref = alloc_ref("HEAD");
        if (!http_fetch_ref(url.buf, ref) &&
            !resolve_remote_symref(ref, refs)) {
                ref->next = refs;
                refs = ref;
        } else {
                free(ref);
        }

        return refs;
}

static void free_discovery(struct discovery *d)
{
        if (d) {
                if (d == last_discovery)
                        last_discovery = NULL;
                free(d->shallow.oid);
                free(d->buf_alloc);
                free_refs(d->refs);
                free(d->service);
                free(d);
        }
}

static int show_http_message(struct strbuf *type, struct strbuf *charset,
                             struct strbuf *msg)
{
        const char *p, *eol;

        /*
         * We only show text/plain parts, as other types are likely
         * to be ugly to look at on the user's terminal.
         */
        if (strcmp(type->buf, "text/plain"))
                return -1;
        if (charset->len)
                strbuf_reencode(msg, charset->buf, get_log_output_encoding());

        strbuf_trim(msg);
        if (!msg->len)
                return -1;

        p = msg->buf;
        do {
                eol = strchrnul(p, '\n');
                fprintf(stderr, "remote: %.*s\n", (int)(eol - p), p);
                p = eol + 1;
        } while(*eol);
        return 0;
}

static int get_protocol_http_header(enum protocol_version version,
                                    struct strbuf *header)
{
        if (version > 0) {
                strbuf_addf(header, GIT_PROTOCOL_HEADER ": version=%d",
                            version);

                return 1;
        }

        return 0;
}

static void check_smart_http(struct discovery *d, const char *service,
                             struct strbuf *type)
{
        const char *p;
        struct packet_reader reader;

        /*
         * If we don't see x-$service-advertisement, then it's not smart-http.
         * But once we do, we commit to it and assume any other protocol
         * violations are hard errors.
         */
        if (!skip_prefix(type->buf, "application/x-", &p) ||
            !skip_prefix(p, service, &p) ||
            strcmp(p, "-advertisement"))
                return;

        packet_reader_init(&reader, -1, d->buf, d->len,
                           PACKET_READ_CHOMP_NEWLINE |
                           PACKET_READ_DIE_ON_ERR_PACKET);
        if (packet_reader_read(&reader) != PACKET_READ_NORMAL)
                die(_("invalid server response; expected service, got flush packet"));

        if (skip_prefix(reader.line, "# service=", &p) && !strcmp(p, service)) {
                /*
                 * The header can include additional metadata lines, up
                 * until a packet flush marker.  Ignore these now, but
                 * in the future we might start to scan them.
                 */
                for (;;) {
                        packet_reader_read(&reader);
                        if (reader.pktlen <= 0) {
                                break;
                        }
                }

                /*
                 * v0 smart http; callers expect us to soak up the
                 * service and header packets
                 */
                d->buf = reader.src_buffer;
                d->len = reader.src_len;
                d->proto_git = 1;

        } else if (!strcmp(reader.line, "version 2")) {
                /*
                 * v2 smart http; do not consume version packet, which will
                 * be handled elsewhere.
                 */
                d->proto_git = 1;

        } else {
                die(_("invalid server response; got '%s'"), reader.line);
        }
}

static struct discovery *discover_refs(const char *service, int for_push)
{
        struct strbuf type = STRBUF_INIT;
        struct strbuf charset = STRBUF_INIT;
        struct strbuf buffer = STRBUF_INIT;
        struct strbuf refs_url = STRBUF_INIT;
        struct strbuf effective_url = STRBUF_INIT;
        struct strbuf protocol_header = STRBUF_INIT;
        struct string_list extra_headers = STRING_LIST_INIT_DUP;
        struct discovery *last = last_discovery;
        int http_ret, maybe_smart = 0;
        struct http_get_options http_options;
        enum protocol_version version = get_protocol_version_config();

        if (last && !strcmp(service, last->service))
                return last;
        free_discovery(last);

        strbuf_addf(&refs_url, "%sinfo/refs", url.buf);
        if ((starts_with(url.buf, "http://") || starts_with(url.buf, "https://")) &&
             git_env_bool("GIT_SMART_HTTP", 1)) {
                maybe_smart = 1;
                if (!strchr(url.buf, '?'))
                        strbuf_addch(&refs_url, '?');
                else
                        strbuf_addch(&refs_url, '&');
                strbuf_addf(&refs_url, "service=%s", service);
        }

        /*
         * NEEDSWORK: If we are trying to use protocol v2 and we are planning
         * to perform a push, then fallback to v0 since the client doesn't know
         * how to push yet using v2.
         */
        if (version == protocol_v2 && !strcmp("git-receive-pack", service))
                version = protocol_v0;

        /* Add the extra Git-Protocol header */
        if (get_protocol_http_header(version, &protocol_header))
                string_list_append(&extra_headers, protocol_header.buf);

        memset(&http_options, 0, sizeof(http_options));
        http_options.content_type = &type;
        http_options.charset = &charset;
        http_options.effective_url = &effective_url;
        http_options.base_url = &url;
        http_options.extra_headers = &extra_headers;
        http_options.initial_request = 1;
        http_options.no_cache = 1;

        http_ret = http_get_strbuf(refs_url.buf, &buffer, &http_options);
        switch (http_ret) {
        case HTTP_OK:
                break;
        case HTTP_MISSING_TARGET:
                show_http_message(&type, &charset, &buffer);
                die(_("repository '%s' not found"),
                    transport_anonymize_url(url.buf));
        case HTTP_NOAUTH:
                show_http_message(&type, &charset, &buffer);
                die(_("Authentication failed for '%s'"),
                    transport_anonymize_url(url.buf));
        default:
                show_http_message(&type, &charset, &buffer);
                die(_("unable to access '%s': %s"),
                    transport_anonymize_url(url.buf), curl_errorstr);
        }

        if (options.verbosity && !starts_with(refs_url.buf, url.buf)) {
                char *u = transport_anonymize_url(url.buf);
                warning(_("redirecting to %s"), u);
                free(u);
        }

        last= xcalloc(1, sizeof(*last_discovery));
        last->service = xstrdup(service);
        last->buf_alloc = strbuf_detach(&buffer, &last->len);
        last->buf = last->buf_alloc;

        if (maybe_smart)
                check_smart_http(last, service, &type);

        if (last->proto_git)
                last->refs = parse_git_refs(last, for_push);
        else
                last->refs = parse_info_refs(last);

        strbuf_release(&refs_url);
        strbuf_release(&type);
        strbuf_release(&charset);
        strbuf_release(&effective_url);
        strbuf_release(&buffer);
        strbuf_release(&protocol_header);
        string_list_clear(&extra_headers, 0);
        last_discovery = last;
        return last;
}

static struct ref *get_refs(int for_push)
{
        struct discovery *heads;

        if (for_push)
                heads = discover_refs("git-receive-pack", for_push);
        else
                heads = discover_refs("git-upload-pack", for_push);

        return heads->refs;
}

static void output_refs(struct ref *refs)
{
        struct ref *posn;
        for (posn = refs; posn; posn = posn->next) {
                if (posn->symref)
                        printf("@%s %s\n", posn->symref, posn->name);
                else
                        printf("%s %s\n", oid_to_hex(&posn->old_oid), posn->name);
        }
        printf("\n");
        fflush(stdout);
}

struct rpc_state {
        const char *service_name;
        char *service_url;
        char *hdr_content_type;
        char *hdr_accept;
        char *protocol_header;
        char *buf;
        size_t alloc;
        size_t len;
        size_t pos;
        int in;
        int out;
        int any_written;
        unsigned gzip_request : 1;
        unsigned initial_buffer : 1;

        /*
         * Whenever a pkt-line is read into buf, append the 4 characters
         * denoting its length before appending the payload.
         */
        unsigned write_line_lengths : 1;

        /*
         * Used by rpc_out; initialize to 0. This is true if a flush has been
         * read, but the corresponding line length (if write_line_lengths is
         * true) and EOF have not been sent to libcurl. Since each flush marks
         * the end of a request, each flush must be completely sent before any
         * further reading occurs.
         */
        unsigned flush_read_but_not_sent : 1;
};

/*
 * Appends the result of reading from rpc->out to the string represented by
 * rpc->buf and rpc->len if there is enough space. Returns 1 if there was
 * enough space, 0 otherwise.
 *
 * If rpc->write_line_lengths is true, appends the line length as a 4-byte
 * hexadecimal string before appending the result described above.
 *
 * Writes the total number of bytes appended into appended.
 */
static int rpc_read_from_out(struct rpc_state *rpc, int options,
                             size_t *appended,
                             enum packet_read_status *status) {
        size_t left;
        char *buf;
        int pktlen_raw;

        if (rpc->write_line_lengths) {
                left = rpc->alloc - rpc->len - 4;
                buf = rpc->buf + rpc->len + 4;
        } else {
                left = rpc->alloc - rpc->len;
                buf = rpc->buf + rpc->len;
        }

        if (left < LARGE_PACKET_MAX)
                return 0;

        *status = packet_read_with_status(rpc->out, NULL, NULL, buf,
                        left, &pktlen_raw, options);
        if (*status != PACKET_READ_EOF) {
                *appended = pktlen_raw + (rpc->write_line_lengths ? 4 : 0);
                rpc->len += *appended;
        }

        if (rpc->write_line_lengths) {
                switch (*status) {
                case PACKET_READ_EOF:
                        if (!(options & PACKET_READ_GENTLE_ON_EOF))
                                die(_("shouldn't have EOF when not gentle on EOF"));
                        break;
                case PACKET_READ_NORMAL:
                        set_packet_header(buf - 4, *appended);
                        break;
                case PACKET_READ_DELIM:
                        memcpy(buf - 4, "0001", 4);
                        break;
                case PACKET_READ_FLUSH:
                        memcpy(buf - 4, "0000", 4);
                        break;
                }
        }

        return 1;
}

static size_t rpc_out(void *ptr, size_t eltsize,
                size_t nmemb, void *buffer_)
{
        size_t max = eltsize * nmemb;
        struct rpc_state *rpc = buffer_;
        size_t avail = rpc->len - rpc->pos;
        enum packet_read_status status;

        if (!avail) {
                rpc->initial_buffer = 0;
                rpc->len = 0;
                rpc->pos = 0;
                if (!rpc->flush_read_but_not_sent) {
                        if (!rpc_read_from_out(rpc, 0, &avail, &status))
                                BUG("The entire rpc->buf should be larger than LARGE_PACKET_MAX");
                        if (status == PACKET_READ_FLUSH)
                                rpc->flush_read_but_not_sent = 1;
                }
                /*
                 * If flush_read_but_not_sent is true, we have already read one
                 * full request but have not fully sent it + EOF, which is why
                 * we need to refrain from reading.
                 */
        }
        if (rpc->flush_read_but_not_sent) {
                if (!avail) {
                        /*
                         * The line length either does not need to be sent at
                         * all or has already been completely sent. Now we can
                         * return 0, indicating EOF, meaning that the flush has
                         * been fully sent.
                         */
                        rpc->flush_read_but_not_sent = 0;
                        return 0;
                }
                /*
                 * If avail is non-zerp, the line length for the flush still
                 * hasn't been fully sent. Proceed with sending the line
                 * length.
                 */
        }

        if (max < avail)
                avail = max;
        memcpy(ptr, rpc->buf + rpc->pos, avail);
        rpc->pos += avail;
        return avail;
}

#ifndef NO_CURL_IOCTL
static curlioerr rpc_ioctl(CURL *handle, int cmd, void *clientp)
{
        struct rpc_state *rpc = clientp;

        switch (cmd) {
        case CURLIOCMD_NOP:
                return CURLIOE_OK;

        case CURLIOCMD_RESTARTREAD:
                if (rpc->initial_buffer) {
                        rpc->pos = 0;
                        return CURLIOE_OK;
                }
                error(_("unable to rewind rpc post data - try increasing http.postBuffer"));
                return CURLIOE_FAILRESTART;

        default:
                return CURLIOE_UNKNOWNCMD;
        }
}
#endif

struct rpc_in_data {
        struct rpc_state *rpc;
        struct active_request_slot *slot;
};

/*
 * A callback for CURLOPT_WRITEFUNCTION. The return value is the bytes consumed
 * from ptr.
 */
static size_t rpc_in(char *ptr, size_t eltsize,
                size_t nmemb, void *buffer_)
{
        size_t size = eltsize * nmemb;
        struct rpc_in_data *data = buffer_;
        long response_code;

        if (curl_easy_getinfo(data->slot->curl, CURLINFO_RESPONSE_CODE,
                              &response_code) != CURLE_OK)
                return size;
        if (response_code >= 300)
                return size;
        if (size)
                data->rpc->any_written = 1;
        write_or_die(data->rpc->in, ptr, size);
        return size;
}

static int run_slot(struct active_request_slot *slot,
                    struct slot_results *results)
{
        int err;
        struct slot_results results_buf;

        if (!results)
                results = &results_buf;

        err = run_one_slot(slot, results);

        if (err != HTTP_OK && err != HTTP_REAUTH) {
                struct strbuf msg = STRBUF_INIT;
                if (results->http_code && results->http_code != 200)
                        strbuf_addf(&msg, "HTTP %ld", results->http_code);
                if (results->curl_result != CURLE_OK) {
                        if (msg.len)
                                strbuf_addch(&msg, ' ');
                        strbuf_addf(&msg, "curl %d", results->curl_result);
                        if (curl_errorstr[0]) {
                                strbuf_addch(&msg, ' ');
                                strbuf_addstr(&msg, curl_errorstr);
                        }
                }
                error(_("RPC failed; %s"), msg.buf);
                strbuf_release(&msg);
        }

        return err;
}

static int probe_rpc(struct rpc_state *rpc, struct slot_results *results)
{
        struct active_request_slot *slot;
        struct curl_slist *headers = http_copy_default_headers();
        struct strbuf buf = STRBUF_INIT;
        int err;

        slot = get_active_slot();

        headers = curl_slist_append(headers, rpc->hdr_content_type);
        headers = curl_slist_append(headers, rpc->hdr_accept);

        curl_easy_setopt(slot->curl, CURLOPT_NOBODY, 0);
        curl_easy_setopt(slot->curl, CURLOPT_POST, 1);
        curl_easy_setopt(slot->curl, CURLOPT_URL, rpc->service_url);
        curl_easy_setopt(slot->curl, CURLOPT_ENCODING, NULL);
        curl_easy_setopt(slot->curl, CURLOPT_POSTFIELDS, "0000");
        curl_easy_setopt(slot->curl, CURLOPT_POSTFIELDSIZE, 4);
        curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, headers);
        curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, fwrite_buffer);
        curl_easy_setopt(slot->curl, CURLOPT_FILE, &buf);

        err = run_slot(slot, results);

        curl_slist_free_all(headers);
        strbuf_release(&buf);
        return err;
}

static curl_off_t xcurl_off_t(size_t len)
{
        uintmax_t size = len;
        if (size > maximum_signed_value_of_type(curl_off_t))
                die(_("cannot handle pushes this big"));
        return (curl_off_t)size;
}

/*
 * If flush_received is true, do not attempt to read any more; just use what's
 * in rpc->buf.
 */
static int post_rpc(struct rpc_state *rpc, int flush_received)
{
        struct active_request_slot *slot;
        struct curl_slist *headers = http_copy_default_headers();
        int use_gzip = rpc->gzip_request;
        char *gzip_body = NULL;
        size_t gzip_size = 0;
        int err, large_request = 0;
        int needs_100_continue = 0;
        struct rpc_in_data rpc_in_data;

        /* Try to load the entire request, if we can fit it into the
         * allocated buffer space we can use HTTP/1.0 and avoid the
         * chunked encoding mess.
         */
        if (!flush_received) {
                while (1) {
                        size_t n;
                        enum packet_read_status status;

                        if (!rpc_read_from_out(rpc, 0, &n, &status)) {
                                large_request = 1;
                                use_gzip = 0;
                                break;
                        }
                        if (status == PACKET_READ_FLUSH)
                                break;
                }
        }

        if (large_request) {
                struct slot_results results;

                do {
                        err = probe_rpc(rpc, &results);
                        if (err == HTTP_REAUTH)
                                credential_fill(&http_auth);
                } while (err == HTTP_REAUTH);
                if (err != HTTP_OK)
                        return -1;

                if (results.auth_avail & CURLAUTH_GSSNEGOTIATE)
                        needs_100_continue = 1;
        }

        headers = curl_slist_append(headers, rpc->hdr_content_type);
        headers = curl_slist_append(headers, rpc->hdr_accept);
        headers = curl_slist_append(headers, needs_100_continue ?
                "Expect: 100-continue" : "Expect:");

        /* Add the extra Git-Protocol header */
        if (rpc->protocol_header)
                headers = curl_slist_append(headers, rpc->protocol_header);

retry:
        slot = get_active_slot();

        curl_easy_setopt(slot->curl, CURLOPT_NOBODY, 0);
        curl_easy_setopt(slot->curl, CURLOPT_POST, 1);
        curl_easy_setopt(slot->curl, CURLOPT_URL, rpc->service_url);
        curl_easy_setopt(slot->curl, CURLOPT_ENCODING, "");

        if (large_request) {
                /* The request body is large and the size cannot be predicted.
                 * We must use chunked encoding to send it.
                 */
                headers = curl_slist_append(headers, "Transfer-Encoding: chunked");
                rpc->initial_buffer = 1;
                curl_easy_setopt(slot->curl, CURLOPT_READFUNCTION, rpc_out);
                curl_easy_setopt(slot->curl, CURLOPT_INFILE, rpc);
#ifndef NO_CURL_IOCTL
                curl_easy_setopt(slot->curl, CURLOPT_IOCTLFUNCTION, rpc_ioctl);
                curl_easy_setopt(slot->curl, CURLOPT_IOCTLDATA, rpc);
#endif
                if (options.verbosity > 1) {
                        fprintf(stderr, "POST %s (chunked)\n", rpc->service_name);
                        fflush(stderr);
                }

        } else if (gzip_body) {
                /*
                 * If we are looping to retry authentication, then the previous
                 * run will have set up the headers and gzip buffer already,
                 * and we just need to send it.
                 */
                curl_easy_setopt(slot->curl, CURLOPT_POSTFIELDS, gzip_body);
                curl_easy_setopt(slot->curl, CURLOPT_POSTFIELDSIZE_LARGE, xcurl_off_t(gzip_size));

        } else if (use_gzip && 1024 < rpc->len) {
                /* The client backend isn't giving us compressed data so
                 * we can try to deflate it ourselves, this may save on
                 * the transfer time.
                 */
                git_zstream stream;
                int ret;

                git_deflate_init_gzip(&stream, Z_BEST_COMPRESSION);
                gzip_size = git_deflate_bound(&stream, rpc->len);
                gzip_body = xmalloc(gzip_size);

                stream.next_in = (unsigned char *)rpc->buf;
                stream.avail_in = rpc->len;
                stream.next_out = (unsigned char *)gzip_body;
                stream.avail_out = gzip_size;

                ret = git_deflate(&stream, Z_FINISH);
                if (ret != Z_STREAM_END)
                        die(_("cannot deflate request; zlib deflate error %d"), ret);

                ret = git_deflate_end_gently(&stream);
                if (ret != Z_OK)
                        die(_("cannot deflate request; zlib end error %d"), ret);

                gzip_size = stream.total_out;

                headers = curl_slist_append(headers, "Content-Encoding: gzip");
                curl_easy_setopt(slot->curl, CURLOPT_POSTFIELDS, gzip_body);
                curl_easy_setopt(slot->curl, CURLOPT_POSTFIELDSIZE_LARGE, xcurl_off_t(gzip_size));

                if (options.verbosity > 1) {
                        fprintf(stderr, "POST %s (gzip %lu to %lu bytes)\n",
                                rpc->service_name,
                                (unsigned long)rpc->len, (unsigned long)gzip_size);
                        fflush(stderr);
                }
        } else {
                /* We know the complete request size in advance, use the
                 * more normal Content-Length approach.
                 */
                curl_easy_setopt(slot->curl, CURLOPT_POSTFIELDS, rpc->buf);
                curl_easy_setopt(slot->curl, CURLOPT_POSTFIELDSIZE_LARGE, xcurl_off_t(rpc->len));
                if (options.verbosity > 1) {
                        fprintf(stderr, "POST %s (%lu bytes)\n",
                                rpc->service_name, (unsigned long)rpc->len);
                        fflush(stderr);
                }
        }

        curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, headers);
        curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, rpc_in);
        rpc_in_data.rpc = rpc;
        rpc_in_data.slot = slot;
        curl_easy_setopt(slot->curl, CURLOPT_FILE, &rpc_in_data);
        curl_easy_setopt(slot->curl, CURLOPT_FAILONERROR, 0);


        rpc->any_written = 0;
        err = run_slot(slot, NULL);
        if (err == HTTP_REAUTH && !large_request) {
                credential_fill(&http_auth);
                goto retry;
        }
        if (err != HTTP_OK)
                err = -1;

        if (!rpc->any_written)
                err = -1;

        curl_slist_free_all(headers);
        free(gzip_body);
        return err;
}

static int rpc_service(struct rpc_state *rpc, struct discovery *heads,
                       const char **client_argv, const struct strbuf *preamble,
                       struct strbuf *rpc_result)
{
        const char *svc = rpc->service_name;
        struct strbuf buf = STRBUF_INIT;
        struct child_process client = CHILD_PROCESS_INIT;
        int err = 0;

        client.in = -1;
        client.out = -1;
        client.git_cmd = 1;
        client.argv = client_argv;
        if (start_command(&client))
                exit(1);
        write_or_die(client.in, preamble->buf, preamble->len);
        if (heads)
                write_or_die(client.in, heads->buf, heads->len);

        rpc->alloc = http_post_buffer;
        rpc->buf = xmalloc(rpc->alloc);
        rpc->in = client.in;
        rpc->out = client.out;

        strbuf_addf(&buf, "%s%s", url.buf, svc);
        rpc->service_url = strbuf_detach(&buf, NULL);

        strbuf_addf(&buf, "Content-Type: application/x-%s-request", svc);
        rpc->hdr_content_type = strbuf_detach(&buf, NULL);

        strbuf_addf(&buf, "Accept: application/x-%s-result", svc);
        rpc->hdr_accept = strbuf_detach(&buf, NULL);

        if (get_protocol_http_header(heads->version, &buf))
                rpc->protocol_header = strbuf_detach(&buf, NULL);
        else
                rpc->protocol_header = NULL;

        while (!err) {
                int n = packet_read(rpc->out, NULL, NULL, rpc->buf, rpc->alloc, 0);
                if (!n)
                        break;
                rpc->pos = 0;
                rpc->len = n;
                err |= post_rpc(rpc, 0);
        }

        close(client.in);
        client.in = -1;
        if (!err) {
                strbuf_read(rpc_result, client.out, 0);
        } else {
                char buf[4096];
                for (;;)
                        if (xread(client.out, buf, sizeof(buf)) <= 0)
                                break;
        }

        close(client.out);
        client.out = -1;

        err |= finish_command(&client);
        free(rpc->service_url);
        free(rpc->hdr_content_type);
        free(rpc->hdr_accept);
        free(rpc->protocol_header);
        free(rpc->buf);
        strbuf_release(&buf);
        return err;
}

static int fetch_dumb(int nr_heads, struct ref **to_fetch)
{
        struct walker *walker;
        char **targets;
        int ret, i;

        ALLOC_ARRAY(targets, nr_heads);
        if (options.depth || options.deepen_since)
                die(_("dumb http transport does not support shallow capabilities"));
        for (i = 0; i < nr_heads; i++)
                targets[i] = xstrdup(oid_to_hex(&to_fetch[i]->old_oid));

        walker = get_http_walker(url.buf);
        walker->get_verbosely = options.verbosity >= 3;
        walker->get_progress = options.progress;
        walker->get_recover = 0;
        ret = walker_fetch(walker, nr_heads, targets, NULL, NULL);
        walker_free(walker);

        for (i = 0; i < nr_heads; i++)
                free(targets[i]);
        free(targets);

        return ret ? error(_("fetch failed.")) : 0;
}

static int fetch_git(struct discovery *heads,
        int nr_heads, struct ref **to_fetch)
{
        struct rpc_state rpc;
        struct strbuf preamble = STRBUF_INIT;
        int i, err;
        struct argv_array args = ARGV_ARRAY_INIT;
        struct strbuf rpc_result = STRBUF_INIT;

        argv_array_pushl(&args, "fetch-pack", "--stateless-rpc",
                         "--stdin", "--lock-pack", NULL);
        if (options.followtags)
                argv_array_push(&args, "--include-tag");
        if (options.thin)
                argv_array_push(&args, "--thin");
        if (options.verbosity >= 3)
                argv_array_pushl(&args, "-v", "-v", NULL);
        if (options.check_self_contained_and_connected)
                argv_array_push(&args, "--check-self-contained-and-connected");
        if (options.cloning)
                argv_array_push(&args, "--cloning");
        if (options.update_shallow)
                argv_array_push(&args, "--update-shallow");
        if (!options.progress)
                argv_array_push(&args, "--no-progress");
        if (options.depth)
                argv_array_pushf(&args, "--depth=%lu", options.depth);
        if (options.deepen_since)
                argv_array_pushf(&args, "--shallow-since=%s", options.deepen_since);
        for (i = 0; i < options.deepen_not.nr; i++)
                argv_array_pushf(&args, "--shallow-exclude=%s",
                                 options.deepen_not.items[i].string);
        if (options.deepen_relative && options.depth)
                argv_array_push(&args, "--deepen-relative");
        if (options.from_promisor)
                argv_array_push(&args, "--from-promisor");
        if (options.no_dependents)
                argv_array_push(&args, "--no-dependents");
        if (options.filter)
                argv_array_pushf(&args, "--filter=%s", options.filter);
        argv_array_push(&args, url.buf);

        for (i = 0; i < nr_heads; i++) {
                struct ref *ref = to_fetch[i];
                if (!*ref->name)
                        die(_("cannot fetch by sha1 over smart http"));
                packet_buf_write(&preamble, "%s %s\n",
                                 oid_to_hex(&ref->old_oid), ref->name);
        }
        packet_buf_flush(&preamble);

        memset(&rpc, 0, sizeof(rpc));
        rpc.service_name = "git-upload-pack",
        rpc.gzip_request = 1;

        err = rpc_service(&rpc, heads, args.argv, &preamble, &rpc_result);
        if (rpc_result.len)
                write_or_die(1, rpc_result.buf, rpc_result.len);
        strbuf_release(&rpc_result);
        strbuf_release(&preamble);
        argv_array_clear(&args);
        return err;
}

static int fetch(int nr_heads, struct ref **to_fetch)
{
        struct discovery *d = discover_refs("git-upload-pack", 0);
        if (d->proto_git)
                return fetch_git(d, nr_heads, to_fetch);
        else
                return fetch_dumb(nr_heads, to_fetch);
}

static void parse_fetch(struct strbuf *buf)
{
        struct ref **to_fetch = NULL;
        struct ref *list_head = NULL;
        struct ref **list = &list_head;
        int alloc_heads = 0, nr_heads = 0;

        do {
                const char *p;
                if (skip_prefix(buf->buf, "fetch ", &p)) {
                        const char *name;
                        struct ref *ref;
                        struct object_id old_oid;
                        const char *q;

                        if (parse_oid_hex(p, &old_oid, &q))
                                die(_("protocol error: expected sha/ref, got '%s'"), p);
                        if (*q == ' ')
                                name = q + 1;
                        else if (!*q)
                                name = "";
                        else
                                die(_("protocol error: expected sha/ref, got '%s'"), p);

                        ref = alloc_ref(name);
                        oidcpy(&ref->old_oid, &old_oid);

                        *list = ref;
                        list = &ref->next;

                        ALLOC_GROW(to_fetch, nr_heads + 1, alloc_heads);
                        to_fetch[nr_heads++] = ref;
                }
                else
                        die(_("http transport does not support %s"), buf->buf);

                strbuf_reset(buf);
                if (strbuf_getline_lf(buf, stdin) == EOF)
                        return;
                if (!*buf->buf)
                        break;
        } while (1);

        if (fetch(nr_heads, to_fetch))
                exit(128); /* error already reported */
        free_refs(list_head);
        free(to_fetch);

        printf("\n");
        fflush(stdout);
        strbuf_reset(buf);
}

static int push_dav(int nr_spec, const char **specs)
{
        struct child_process child = CHILD_PROCESS_INIT;
        size_t i;

        child.git_cmd = 1;
        argv_array_push(&child.args, "http-push");
        argv_array_push(&child.args, "--helper-status");
        if (options.dry_run)
                argv_array_push(&child.args, "--dry-run");
        if (options.verbosity > 1)
                argv_array_push(&child.args, "--verbose");
        argv_array_push(&child.args, url.buf);
        for (i = 0; i < nr_spec; i++)
                argv_array_push(&child.args, specs[i]);

        if (run_command(&child))
                die(_("git-http-push failed"));
        return 0;
}

static int push_git(struct discovery *heads, int nr_spec, const char **specs)
{
        struct rpc_state rpc;
        int i, err;
        struct argv_array args;
        struct string_list_item *cas_option;
        struct strbuf preamble = STRBUF_INIT;
        struct strbuf rpc_result = STRBUF_INIT;

        argv_array_init(&args);
        argv_array_pushl(&args, "send-pack", "--stateless-rpc", "--helper-status",
                         NULL);

        if (options.thin)
                argv_array_push(&args, "--thin");
        if (options.dry_run)
                argv_array_push(&args, "--dry-run");
        if (options.push_cert == SEND_PACK_PUSH_CERT_ALWAYS)
                argv_array_push(&args, "--signed=yes");
        else if (options.push_cert == SEND_PACK_PUSH_CERT_IF_ASKED)
                argv_array_push(&args, "--signed=if-asked");
        if (options.atomic)
                argv_array_push(&args, "--atomic");
        if (options.verbosity == 0)
                argv_array_push(&args, "--quiet");
        else if (options.verbosity > 1)
                argv_array_push(&args, "--verbose");
        for (i = 0; i < options.push_options.nr; i++)
                argv_array_pushf(&args, "--push-option=%s",
                                 options.push_options.items[i].string);
        argv_array_push(&args, options.progress ? "--progress" : "--no-progress");
        for_each_string_list_item(cas_option, &cas_options)
                argv_array_push(&args, cas_option->string);
        argv_array_push(&args, url.buf);

        argv_array_push(&args, "--stdin");
        for (i = 0; i < nr_spec; i++)
                packet_buf_write(&preamble, "%s\n", specs[i]);
        packet_buf_flush(&preamble);

        memset(&rpc, 0, sizeof(rpc));
        rpc.service_name = "git-receive-pack",

        err = rpc_service(&rpc, heads, args.argv, &preamble, &rpc_result);
        if (rpc_result.len)
                write_or_die(1, rpc_result.buf, rpc_result.len);
        strbuf_release(&rpc_result);
        strbuf_release(&preamble);
        argv_array_clear(&args);
        return err;
}

static int push(int nr_spec, const char **specs)
{
        struct discovery *heads = discover_refs("git-receive-pack", 1);
        int ret;

        if (heads->proto_git)
                ret = push_git(heads, nr_spec, specs);
        else
                ret = push_dav(nr_spec, specs);
        free_discovery(heads);
        return ret;
}

static void parse_push(struct strbuf *buf)
{
        struct argv_array specs = ARGV_ARRAY_INIT;
        int ret;

        do {
                const char *arg;
                if (skip_prefix(buf->buf, "push ", &arg))
                        argv_array_push(&specs, arg);
                else
                        die(_("http transport does not support %s"), buf->buf);

                strbuf_reset(buf);
                if (strbuf_getline_lf(buf, stdin) == EOF)
                        goto free_specs;
                if (!*buf->buf)
                        break;
        } while (1);

        ret = push(specs.argc, specs.argv);
        printf("\n");
        fflush(stdout);

        if (ret)
                exit(128); /* error already reported */

 free_specs:
        argv_array_clear(&specs);
}

static int stateless_connect(const char *service_name)
{
        struct discovery *discover;
        struct rpc_state rpc;
        struct strbuf buf = STRBUF_INIT;

        /*
         * Run the info/refs request and see if the server supports protocol
         * v2.  If and only if the server supports v2 can we successfully
         * establish a stateless connection, otherwise we need to tell the
         * client to fallback to using other transport helper functions to
         * complete their request.
         */
        discover = discover_refs(service_name, 0);
        if (discover->version != protocol_v2) {
                printf("fallback\n");
                fflush(stdout);
                return -1;
        } else {
                /* Stateless Connection established */
                printf("\n");
                fflush(stdout);
        }

        rpc.service_name = service_name;
        rpc.service_url = xstrfmt("%s%s", url.buf, rpc.service_name);
        rpc.hdr_content_type = xstrfmt("Content-Type: application/x-%s-request", rpc.service_name);
        rpc.hdr_accept = xstrfmt("Accept: application/x-%s-result", rpc.service_name);
        if (get_protocol_http_header(discover->version, &buf)) {
                rpc.protocol_header = strbuf_detach(&buf, NULL);
        } else {
                rpc.protocol_header = NULL;
                strbuf_release(&buf);
        }
        rpc.buf = xmalloc(http_post_buffer);
        rpc.alloc = http_post_buffer;
        rpc.len = 0;
        rpc.pos = 0;
        rpc.in = 1;
        rpc.out = 0;
        rpc.any_written = 0;
        rpc.gzip_request = 1;
        rpc.initial_buffer = 0;
        rpc.write_line_lengths = 1;
        rpc.flush_read_but_not_sent = 0;

        /*
         * Dump the capability listing that we got from the server earlier
         * during the info/refs request.
         */
        write_or_die(rpc.in, discover->buf, discover->len);

        /* Until we see EOF keep sending POSTs */
        while (1) {
                size_t avail;
                enum packet_read_status status;

                if (!rpc_read_from_out(&rpc, PACKET_READ_GENTLE_ON_EOF, &avail,
                                       &status))
                        BUG("The entire rpc->buf should be larger than LARGE_PACKET_MAX");
                if (status == PACKET_READ_EOF)
                        break;
                if (post_rpc(&rpc, status == PACKET_READ_FLUSH))
                        /* We would have an err here */
                        break;
                /* Reset the buffer for next request */
                rpc.len = 0;
        }

        free(rpc.service_url);
        free(rpc.hdr_content_type);
        free(rpc.hdr_accept);
        free(rpc.protocol_header);
        free(rpc.buf);
        strbuf_release(&buf);

        return 0;
}

int cmd_main(int argc, const char **argv)
{
        struct strbuf buf = STRBUF_INIT;
        int nongit;

        setup_git_directory_gently(&nongit);
        if (argc < 2) {
                error(_("remote-curl: usage: git remote-curl <remote> [<url>]"));
                return 1;
        }

        options.verbosity = 1;
        options.progress = !!isatty(2);
        options.thin = 1;
        string_list_init(&options.deepen_not, 1);
        string_list_init(&options.push_options, 1);

        /*
         * Just report "remote-curl" here (folding all the various aliases
         * ("git-remote-http", "git-remote-https", and etc.) here since they
         * are all just copies of the same actual executable.
         */
        trace2_cmd_name("remote-curl");

        remote = remote_get(argv[1]);

        if (argc > 2) {
                end_url_with_slash(&url, argv[2]);
        } else {
                end_url_with_slash(&url, remote->url[0]);
        }

        http_init(remote, url.buf, 0);

        do {
                const char *arg;

                if (strbuf_getline_lf(&buf, stdin) == EOF) {
                        if (ferror(stdin))
                                error(_("remote-curl: error reading command stream from git"));
                        return 1;
                }
                if (buf.len == 0)
                        break;
                if (starts_with(buf.buf, "fetch ")) {
                        if (nongit)
                                die(_("remote-curl: fetch attempted without a local repo"));
                        parse_fetch(&buf);

                } else if (!strcmp(buf.buf, "list") || starts_with(buf.buf, "list ")) {
                        int for_push = !!strstr(buf.buf + 4, "for-push");
                        output_refs(get_refs(for_push));

                } else if (starts_with(buf.buf, "push ")) {
                        parse_push(&buf);

                } else if (skip_prefix(buf.buf, "option ", &arg)) {
                        char *value = strchr(arg, ' ');
                        int result;

                        if (value)
                                *value++ = '\0';
                        else
                                value = "true";

                        result = set_option(arg, value);
                        if (!result)
                                printf("ok\n");
                        else if (result < 0)
                                printf("error invalid value\n");
                        else
                                printf("unsupported\n");
                        fflush(stdout);

                } else if (!strcmp(buf.buf, "capabilities")) {
                        printf("stateless-connect\n");
                        printf("fetch\n");
                        printf("option\n");
                        printf("push\n");
                        printf("check-connectivity\n");
                        printf("\n");
                        fflush(stdout);
                } else if (skip_prefix(buf.buf, "stateless-connect ", &arg)) {
                        if (!stateless_connect(arg))
                                break;
                } else {
                        error(_("remote-curl: unknown command '%s' from git"), buf.buf);
                        return 1;
                }
                strbuf_reset(&buf);
        } while (1);

        http_cleanup();

        return 0;
}