#include "http.h"
#include "pack.h"
#include "sideband.h"
#include "run-command.h"
#include "url.h"

int data_received;
int active_requests;
int http_is_verbose;
size_t http_post_buffer = 16 * LARGE_PACKET_MAX;

#if LIBCURL_VERSION_NUM >= 0x070a06
#define LIBCURL_CAN_HANDLE_AUTH_ANY
#endif

static int min_curl_sessions = 1;
static int curl_session_count;
#ifdef USE_CURL_MULTI
static int max_requests = -1;
static CURLM *curlm;
#endif
#ifndef NO_CURL_EASY_DUPHANDLE
static CURL *curl_default;
#endif

#define PREV_BUF_SIZE 4096
#define RANGE_HEADER_SIZE 30

char curl_errorstr[CURL_ERROR_SIZE];

static int curl_ssl_verify = -1;
static const char *ssl_cert;
#if LIBCURL_VERSION_NUM >= 0x070903
static const char *ssl_key;
#endif
#if LIBCURL_VERSION_NUM >= 0x070908
static const char *ssl_capath;
#endif
static const char *ssl_cainfo;
static long curl_low_speed_limit = -1;
static long curl_low_speed_time = -1;
static int curl_ftp_no_epsv;
static const char *curl_http_proxy;
static const char *curl_cookie_file;
static char *user_name, *user_pass, *description;
static const char *user_agent;

#if LIBCURL_VERSION_NUM >= 0x071700
/* Use CURLOPT_KEYPASSWD as is */
#elif LIBCURL_VERSION_NUM >= 0x070903
#define CURLOPT_KEYPASSWD CURLOPT_SSLKEYPASSWD
#else
#define CURLOPT_KEYPASSWD CURLOPT_SSLCERTPASSWD
#endif

static char *ssl_cert_password;
static int ssl_cert_password_required;

static struct curl_slist *pragma_header;
static struct curl_slist *no_pragma_header;

static struct active_request_slot *active_queue_head;

size_t fread_buffer(char *ptr, size_t eltsize, size_t nmemb, void *buffer_)
{
        size_t size = eltsize * nmemb;
        struct buffer *buffer = buffer_;

        if (size > buffer->buf.len - buffer->posn)
                size = buffer->buf.len - buffer->posn;
        memcpy(ptr, buffer->buf.buf + buffer->posn, size);
        buffer->posn += size;

        return size;
}

#ifndef NO_CURL_IOCTL
curlioerr ioctl_buffer(CURL *handle, int cmd, void *clientp)
{
        struct buffer *buffer = clientp;

        switch (cmd) {
        case CURLIOCMD_NOP:
                return CURLIOE_OK;

        case CURLIOCMD_RESTARTREAD:
                buffer->posn = 0;
                return CURLIOE_OK;

        default:
                return CURLIOE_UNKNOWNCMD;
        }
}
#endif

size_t fwrite_buffer(char *ptr, size_t eltsize, size_t nmemb, void *buffer_)
{
        size_t size = eltsize * nmemb;
        struct strbuf *buffer = buffer_;

        strbuf_add(buffer, ptr, size);
        data_received++;
        return size;
}

size_t fwrite_null(char *ptr, size_t eltsize, size_t nmemb, void *strbuf)
{
        data_received++;
        return eltsize * nmemb;
}

#ifdef USE_CURL_MULTI
static void process_curl_messages(void)
{
        int num_messages;
        struct active_request_slot *slot;
        CURLMsg *curl_message = curl_multi_info_read(curlm, &num_messages);

        while (curl_message != NULL) {
                if (curl_message->msg == CURLMSG_DONE) {
                        int curl_result = curl_message->data.result;
                        slot = active_queue_head;
                        while (slot != NULL &&
                               slot->curl != curl_message->easy_handle)
                                slot = slot->next;
                        if (slot != NULL) {
                                curl_multi_remove_handle(curlm, slot->curl);
                                slot->curl_result = curl_result;
                                finish_active_slot(slot);
                        } else {
                                fprintf(stderr, "Received DONE message for unknown request!\n");
                        }
                } else {
                        fprintf(stderr, "Unknown CURL message received: %d\n",
                                (int)curl_message->msg);
                }
                curl_message = curl_multi_info_read(curlm, &num_messages);
        }
}
#endif

static char *git_getpass_with_description(const char *what, const char *desc)
{
        struct strbuf prompt = STRBUF_INIT;
        char *r;

        if (desc)
                strbuf_addf(&prompt, "%s for '%s': ", what, desc);
        else
                strbuf_addf(&prompt, "%s: ", what);
        /*
         * NEEDSWORK: for usernames, we should do something less magical that
         * actually echoes the characters. However, we need to read from
         * /dev/tty and not stdio, which is not portable (but getpass will do
         * it for us). http.c uses the same workaround.
         */
        r = git_getpass(prompt.buf);

        strbuf_release(&prompt);
        return xstrdup(r);
}

static int http_options(const char *var, const char *value, void *cb)
{
        if (!strcmp("http.sslverify", var)) {
                curl_ssl_verify = git_config_bool(var, value);
                return 0;
        }
        if (!strcmp("http.sslcert", var))
                return git_config_string(&ssl_cert, var, value);
#if LIBCURL_VERSION_NUM >= 0x070903
        if (!strcmp("http.sslkey", var))
                return git_config_string(&ssl_key, var, value);
#endif
#if LIBCURL_VERSION_NUM >= 0x070908
        if (!strcmp("http.sslcapath", var))
                return git_config_string(&ssl_capath, var, value);
#endif
        if (!strcmp("http.sslcainfo", var))
                return git_config_string(&ssl_cainfo, var, value);
        if (!strcmp("http.sslcertpasswordprotected", var)) {
                if (git_config_bool(var, value))
                        ssl_cert_password_required = 1;
                return 0;
        }
        if (!strcmp("http.minsessions", var)) {
                min_curl_sessions = git_config_int(var, value);
#ifndef USE_CURL_MULTI
                if (min_curl_sessions > 1)
                        min_curl_sessions = 1;
#endif
                return 0;
        }
#ifdef USE_CURL_MULTI
        if (!strcmp("http.maxrequests", var)) {
                max_requests = git_config_int(var, value);
                return 0;
        }
#endif
        if (!strcmp("http.lowspeedlimit", var)) {
                curl_low_speed_limit = (long)git_config_int(var, value);
                return 0;
        }
        if (!strcmp("http.lowspeedtime", var)) {
                curl_low_speed_time = (long)git_config_int(var, value);
                return 0;
        }

        if (!strcmp("http.noepsv", var)) {
                curl_ftp_no_epsv = git_config_bool(var, value);
                return 0;
        }
        if (!strcmp("http.proxy", var))
                return git_config_string(&curl_http_proxy, var, value);

        if (!strcmp("http.cookiefile", var))
                return git_config_string(&curl_cookie_file, var, value);

        if (!strcmp("http.postbuffer", var)) {
                http_post_buffer = git_config_int(var, value);
                if (http_post_buffer < LARGE_PACKET_MAX)
                        http_post_buffer = LARGE_PACKET_MAX;
                return 0;
        }

        if (!strcmp("http.useragent", var))
                return git_config_string(&user_agent, var, value);

        /* Fall back on the default ones */
        return git_default_config(var, value, cb);
}

static void init_curl_http_auth(CURL *result)
{
        if (user_name) {
                struct strbuf up = STRBUF_INIT;
                if (!user_pass)
                        user_pass = xstrdup(git_getpass_with_description("Password", description));
                strbuf_addf(&up, "%s:%s", user_name, user_pass);
                curl_easy_setopt(result, CURLOPT_USERPWD,
                                 strbuf_detach(&up, NULL));
        }
}

static int has_cert_password(void)
{
        if (ssl_cert_password != NULL)
                return 1;
        if (ssl_cert == NULL || ssl_cert_password_required != 1)
                return 0;
        /* Only prompt the user once. */
        ssl_cert_password_required = -1;
        ssl_cert_password = git_getpass_with_description("Certificate Password", description);
        if (ssl_cert_password != NULL) {
                ssl_cert_password = xstrdup(ssl_cert_password);
                return 1;
        } else
                return 0;
}

static CURL *get_curl_handle(void)
{
        CURL *result = curl_easy_init();

        if (!curl_ssl_verify) {
                curl_easy_setopt(result, CURLOPT_SSL_VERIFYPEER, 0);
                curl_easy_setopt(result, CURLOPT_SSL_VERIFYHOST, 0);
        } else {
                /* Verify authenticity of the peer's certificate */
                curl_easy_setopt(result, CURLOPT_SSL_VERIFYPEER, 1);
                /* The name in the cert must match whom we tried to connect */
                curl_easy_setopt(result, CURLOPT_SSL_VERIFYHOST, 2);
        }

#if LIBCURL_VERSION_NUM >= 0x070907
        curl_easy_setopt(result, CURLOPT_NETRC, CURL_NETRC_OPTIONAL);
#endif
#ifdef LIBCURL_CAN_HANDLE_AUTH_ANY
        curl_easy_setopt(result, CURLOPT_HTTPAUTH, CURLAUTH_ANY);
#endif

        init_curl_http_auth(result);

        if (ssl_cert != NULL)
                curl_easy_setopt(result, CURLOPT_SSLCERT, ssl_cert);
        if (has_cert_password())
                curl_easy_setopt(result, CURLOPT_KEYPASSWD, ssl_cert_password);
#if LIBCURL_VERSION_NUM >= 0x070903
        if (ssl_key != NULL)
                curl_easy_setopt(result, CURLOPT_SSLKEY, ssl_key);
#endif
#if LIBCURL_VERSION_NUM >= 0x070908
        if (ssl_capath != NULL)
                curl_easy_setopt(result, CURLOPT_CAPATH, ssl_capath);
#endif
        if (ssl_cainfo != NULL)
                curl_easy_setopt(result, CURLOPT_CAINFO, ssl_cainfo);
        curl_easy_setopt(result, CURLOPT_FAILONERROR, 1);

        if (curl_low_speed_limit > 0 && curl_low_speed_time > 0) {
                curl_easy_setopt(result, CURLOPT_LOW_SPEED_LIMIT,
                                 curl_low_speed_limit);
                curl_easy_setopt(result, CURLOPT_LOW_SPEED_TIME,
                                 curl_low_speed_time);
        }

        curl_easy_setopt(result, CURLOPT_FOLLOWLOCATION, 1);
#if LIBCURL_VERSION_NUM >= 0x071301
        curl_easy_setopt(result, CURLOPT_POSTREDIR, CURL_REDIR_POST_ALL);
#elif LIBCURL_VERSION_NUM >= 0x071101
        curl_easy_setopt(result, CURLOPT_POST301, 1);
#endif

        if (getenv("GIT_CURL_VERBOSE"))
                curl_easy_setopt(result, CURLOPT_VERBOSE, 1);

        curl_easy_setopt(result, CURLOPT_USERAGENT,
                user_agent ? user_agent : GIT_HTTP_USER_AGENT);

        if (curl_ftp_no_epsv)
                curl_easy_setopt(result, CURLOPT_FTP_USE_EPSV, 0);

        if (curl_http_proxy)
                curl_easy_setopt(result, CURLOPT_PROXY, curl_http_proxy);

        return result;
}

static void http_auth_init(const char *url)
{
        const char *at, *colon, *cp, *slash, *host;

        cp = strstr(url, "://");
        if (!cp)
                return;

        /*
         * Ok, the URL looks like "proto://something".  Which one?
         * "proto://<user>:<pass>@<host>/...",
         * "proto://<user>@<host>/...", or just
         * "proto://<host>/..."?
         */
        cp += 3;
        at = strchr(cp, '@');
        colon = strchr(cp, ':');
        slash = strchrnul(cp, '/');
        if (!at || slash <= at) {
                /* No credentials, but we may have to ask for some later */
                host = cp;
        }
        else if (!colon || at <= colon) {
                /* Only username */
                user_name = url_decode_mem(cp, at - cp);
                user_pass = NULL;
                host = at + 1;
        } else {
                user_name = url_decode_mem(cp, colon - cp);
                user_pass = url_decode_mem(colon + 1, at - (colon + 1));
                host = at + 1;
        }

        description = url_decode_mem(host, slash - host);
}

static void set_from_env(const char **var, const char *envname)
{
        const char *val = getenv(envname);
        if (val)
                *var = val;
}

void http_init(struct remote *remote, const char *url)
{
        char *low_speed_limit;
        char *low_speed_time;

        http_is_verbose = 0;

        git_config(http_options, NULL);

        curl_global_init(CURL_GLOBAL_ALL);

        if (remote && remote->http_proxy)
                curl_http_proxy = xstrdup(remote->http_proxy);

        pragma_header = curl_slist_append(pragma_header, "Pragma: no-cache");
        no_pragma_header = curl_slist_append(no_pragma_header, "Pragma:");

#ifdef USE_CURL_MULTI
        {
                char *http_max_requests = getenv("GIT_HTTP_MAX_REQUESTS");
                if (http_max_requests != NULL)
                        max_requests = atoi(http_max_requests);
        }

        curlm = curl_multi_init();
        if (curlm == NULL) {
                fprintf(stderr, "Error creating curl multi handle.\n");
                exit(1);
        }
#endif

        if (getenv("GIT_SSL_NO_VERIFY"))
                curl_ssl_verify = 0;

        set_from_env(&ssl_cert, "GIT_SSL_CERT");
#if LIBCURL_VERSION_NUM >= 0x070903
        set_from_env(&ssl_key, "GIT_SSL_KEY");
#endif
#if LIBCURL_VERSION_NUM >= 0x070908
        set_from_env(&ssl_capath, "GIT_SSL_CAPATH");
#endif
        set_from_env(&ssl_cainfo, "GIT_SSL_CAINFO");

        set_from_env(&user_agent, "GIT_HTTP_USER_AGENT");

        low_speed_limit = getenv("GIT_HTTP_LOW_SPEED_LIMIT");
        if (low_speed_limit != NULL)
                curl_low_speed_limit = strtol(low_speed_limit, NULL, 10);
        low_speed_time = getenv("GIT_HTTP_LOW_SPEED_TIME");
        if (low_speed_time != NULL)
                curl_low_speed_time = strtol(low_speed_time, NULL, 10);

        if (curl_ssl_verify == -1)
                curl_ssl_verify = 1;

        curl_session_count = 0;
#ifdef USE_CURL_MULTI
        if (max_requests < 1)
                max_requests = DEFAULT_MAX_REQUESTS;
#endif

        if (getenv("GIT_CURL_FTP_NO_EPSV"))
                curl_ftp_no_epsv = 1;

        if (url) {
                http_auth_init(url);
                if (!ssl_cert_password_required &&
                    getenv("GIT_SSL_CERT_PASSWORD_PROTECTED") &&
                    !prefixcmp(url, "https://"))
                        ssl_cert_password_required = 1;
        }

#ifndef NO_CURL_EASY_DUPHANDLE
        curl_default = get_curl_handle();
#endif
}

void http_cleanup(void)
{
        struct active_request_slot *slot = active_queue_head;

        while (slot != NULL) {
                struct active_request_slot *next = slot->next;
                if (slot->curl != NULL) {
#ifdef USE_CURL_MULTI
                        curl_multi_remove_handle(curlm, slot->curl);
#endif
                        curl_easy_cleanup(slot->curl);
                }
                free(slot);
                slot = next;
        }
        active_queue_head = NULL;

#ifndef NO_CURL_EASY_DUPHANDLE
        curl_easy_cleanup(curl_default);
#endif

#ifdef USE_CURL_MULTI
        curl_multi_cleanup(curlm);
#endif
        curl_global_cleanup();

        curl_slist_free_all(pragma_header);
        pragma_header = NULL;

        curl_slist_free_all(no_pragma_header);
        no_pragma_header = NULL;

        if (curl_http_proxy) {
                free((void *)curl_http_proxy);
                curl_http_proxy = NULL;
        }

        if (ssl_cert_password != NULL) {
                memset(ssl_cert_password, 0, strlen(ssl_cert_password));
                free(ssl_cert_password);
                ssl_cert_password = NULL;
        }
        ssl_cert_password_required = 0;
}

struct active_request_slot *get_active_slot(void)
{
        struct active_request_slot *slot = active_queue_head;
        struct active_request_slot *newslot;

#ifdef USE_CURL_MULTI
        int num_transfers;

        /* Wait for a slot to open up if the queue is full */
        while (active_requests >= max_requests) {
                curl_multi_perform(curlm, &num_transfers);
                if (num_transfers < active_requests)
                        process_curl_messages();
        }
#endif

        while (slot != NULL && slot->in_use)
                slot = slot->next;

        if (slot == NULL) {
                newslot = xmalloc(sizeof(*newslot));
                newslot->curl = NULL;
                newslot->in_use = 0;
                newslot->next = NULL;

                slot = active_queue_head;
                if (slot == NULL) {
                        active_queue_head = newslot;
                } else {
                        while (slot->next != NULL)
                                slot = slot->next;
                        slot->next = newslot;
                }
                slot = newslot;
        }

        if (slot->curl == NULL) {
#ifdef NO_CURL_EASY_DUPHANDLE
                slot->curl = get_curl_handle();
#else
                slot->curl = curl_easy_duphandle(curl_default);
#endif
                curl_session_count++;
        }

        active_requests++;
        slot->in_use = 1;
        slot->local = NULL;
        slot->results = NULL;
        slot->finished = NULL;
        slot->callback_data = NULL;
        slot->callback_func = NULL;
        curl_easy_setopt(slot->curl, CURLOPT_COOKIEFILE, curl_cookie_file);
        curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, pragma_header);
        curl_easy_setopt(slot->curl, CURLOPT_ERRORBUFFER, curl_errorstr);
        curl_easy_setopt(slot->curl, CURLOPT_CUSTOMREQUEST, NULL);
        curl_easy_setopt(slot->curl, CURLOPT_READFUNCTION, NULL);
        curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, NULL);
        curl_easy_setopt(slot->curl, CURLOPT_POSTFIELDS, NULL);
        curl_easy_setopt(slot->curl, CURLOPT_UPLOAD, 0);
        curl_easy_setopt(slot->curl, CURLOPT_HTTPGET, 1);

        return slot;
}

int start_active_slot(struct active_request_slot *slot)
{
#ifdef USE_CURL_MULTI
        CURLMcode curlm_result = curl_multi_add_handle(curlm, slot->curl);
        int num_transfers;

        if (curlm_result != CURLM_OK &&
            curlm_result != CURLM_CALL_MULTI_PERFORM) {
                active_requests--;
                slot->in_use = 0;
                return 0;
        }

        /*
         * We know there must be something to do, since we just added
         * something.
         */
        curl_multi_perform(curlm, &num_transfers);
#endif
        return 1;
}

#ifdef USE_CURL_MULTI
struct fill_chain {
        void *data;
        int (*fill)(void *);
        struct fill_chain *next;
};

static struct fill_chain *fill_cfg;

void add_fill_function(void *data, int (*fill)(void *))
{
        struct fill_chain *new = xmalloc(sizeof(*new));
        struct fill_chain **linkp = &fill_cfg;
        new->data = data;
        new->fill = fill;
        new->next = NULL;
        while (*linkp)
                linkp = &(*linkp)->next;
        *linkp = new;
}

void fill_active_slots(void)
{
        struct active_request_slot *slot = active_queue_head;

        while (active_requests < max_requests) {
                struct fill_chain *fill;
                for (fill = fill_cfg; fill; fill = fill->next)
                        if (fill->fill(fill->data))
                                break;

                if (!fill)
                        break;
        }

        while (slot != NULL) {
                if (!slot->in_use && slot->curl != NULL
                        && curl_session_count > min_curl_sessions) {
                        curl_easy_cleanup(slot->curl);
                        slot->curl = NULL;
                        curl_session_count--;
                }
                slot = slot->next;
        }
}

void step_active_slots(void)
{
        int num_transfers;
        CURLMcode curlm_result;

        do {
                curlm_result = curl_multi_perform(curlm, &num_transfers);
        } while (curlm_result == CURLM_CALL_MULTI_PERFORM);
        if (num_transfers < active_requests) {
                process_curl_messages();
                fill_active_slots();
        }
}
#endif

void run_active_slot(struct active_request_slot *slot)
{
#ifdef USE_CURL_MULTI
        long last_pos = 0;
        long current_pos;
        fd_set readfds;
        fd_set writefds;
        fd_set excfds;
        int max_fd;
        struct timeval select_timeout;
        int finished = 0;

        slot->finished = &finished;
        while (!finished) {
                data_received = 0;
                step_active_slots();

                if (!data_received && slot->local != NULL) {
                        current_pos = ftell(slot->local);
                        if (current_pos > last_pos)
                                data_received++;
                        last_pos = current_pos;
                }

                if (slot->in_use && !data_received) {
                        max_fd = 0;
                        FD_ZERO(&readfds);
                        FD_ZERO(&writefds);
                        FD_ZERO(&excfds);
                        select_timeout.tv_sec = 0;
                        select_timeout.tv_usec = 50000;
                        select(max_fd, &readfds, &writefds,
                               &excfds, &select_timeout);
                }
        }
#else
        while (slot->in_use) {
                slot->curl_result = curl_easy_perform(slot->curl);
                finish_active_slot(slot);
        }
#endif
}

static void closedown_active_slot(struct active_request_slot *slot)
{
        active_requests--;
        slot->in_use = 0;
}

static void release_active_slot(struct active_request_slot *slot)
{
        closedown_active_slot(slot);
        if (slot->curl && curl_session_count > min_curl_sessions) {
#ifdef USE_CURL_MULTI
                curl_multi_remove_handle(curlm, slot->curl);
#endif
                curl_easy_cleanup(slot->curl);
                slot->curl = NULL;
                curl_session_count--;
        }
#ifdef USE_CURL_MULTI
        fill_active_slots();
#endif
}

void finish_active_slot(struct active_request_slot *slot)
{
        closedown_active_slot(slot);
        curl_easy_getinfo(slot->curl, CURLINFO_HTTP_CODE, &slot->http_code);

        if (slot->finished != NULL)
                (*slot->finished) = 1;

        /* Store slot results so they can be read after the slot is reused */
        if (slot->results != NULL) {
                slot->results->curl_result = slot->curl_result;
                slot->results->http_code = slot->http_code;
        }

        /* Run callback if appropriate */
        if (slot->callback_func != NULL)
                slot->callback_func(slot->callback_data);
}

void finish_all_active_slots(void)
{
        struct active_request_slot *slot = active_queue_head;

        while (slot != NULL)
                if (slot->in_use) {
                        run_active_slot(slot);
                        slot = active_queue_head;
                } else {
                        slot = slot->next;
                }
}

/* Helpers for modifying and creating URLs */
static inline int needs_quote(int ch)
{
        if (((ch >= 'A') && (ch <= 'Z'))
                        || ((ch >= 'a') && (ch <= 'z'))
                        || ((ch >= '0') && (ch <= '9'))
                        || (ch == '/')
                        || (ch == '-')
                        || (ch == '.'))
                return 0;
        return 1;
}

static inline int hex(int v)
{
        if (v < 10)
                return '0' + v;
        else
                return 'A' + v - 10;
}

static char *quote_ref_url(const char *base, const char *ref)
{
        struct strbuf buf = STRBUF_INIT;
        const char *cp;
        int ch;

        end_url_with_slash(&buf, base);

        for (cp = ref; (ch = *cp) != 0; cp++)
                if (needs_quote(ch))
                        strbuf_addf(&buf, "%%%02x", ch);
                else
                        strbuf_addch(&buf, *cp);

        return strbuf_detach(&buf, NULL);
}

void append_remote_object_url(struct strbuf *buf, const char *url,
                              const char *hex,
                              int only_two_digit_prefix)
{
        end_url_with_slash(buf, url);

        strbuf_addf(buf, "objects/%.*s/", 2, hex);
        if (!only_two_digit_prefix)
                strbuf_addf(buf, "%s", hex+2);
}

char *get_remote_object_url(const char *url, const char *hex,
                            int only_two_digit_prefix)
{
        struct strbuf buf = STRBUF_INIT;
        append_remote_object_url(&buf, url, hex, only_two_digit_prefix);
        return strbuf_detach(&buf, NULL);
}

/* http_request() targets */
#define HTTP_REQUEST_STRBUF     0
#define HTTP_REQUEST_FILE       1

static int http_request(const char *url, void *result, int target, int options)
{
        struct active_request_slot *slot;
        struct slot_results results;
        struct curl_slist *headers = NULL;
        struct strbuf buf = STRBUF_INIT;
        int ret;

        slot = get_active_slot();
        slot->results = &results;
        curl_easy_setopt(slot->curl, CURLOPT_HTTPGET, 1);

        if (result == NULL) {
                curl_easy_setopt(slot->curl, CURLOPT_NOBODY, 1);
        } else {
                curl_easy_setopt(slot->curl, CURLOPT_NOBODY, 0);
                curl_easy_setopt(slot->curl, CURLOPT_FILE, result);

                if (target == HTTP_REQUEST_FILE) {
                        long posn = ftell(result);
                        curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION,
                                         fwrite);
                        if (posn > 0) {
                                strbuf_addf(&buf, "Range: bytes=%ld-", posn);
                                headers = curl_slist_append(headers, buf.buf);
                                strbuf_reset(&buf);
                        }
                        slot->local = result;
                } else
                        curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION,
                                         fwrite_buffer);
        }

        strbuf_addstr(&buf, "Pragma:");
        if (options & HTTP_NO_CACHE)
                strbuf_addstr(&buf, " no-cache");

        headers = curl_slist_append(headers, buf.buf);

        curl_easy_setopt(slot->curl, CURLOPT_URL, url);
        curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, headers);

        if (start_active_slot(slot)) {
                run_active_slot(slot);
                if (results.curl_result == CURLE_OK)
                        ret = HTTP_OK;
                else if (missing_target(&results))
                        ret = HTTP_MISSING_TARGET;
                else if (results.http_code == 401) {
                        if (user_name) {
                                ret = HTTP_NOAUTH;
                        } else {
                                /*
                                 * git_getpass is needed here because its very likely stdin/stdout are
                                 * pipes to our parent process.  So we instead need to use /dev/tty,
                                 * but that is non-portable.  Using git_getpass() can at least be stubbed
                                 * on other platforms with a different implementation if/when necessary.
                                 */
                                user_name = xstrdup(git_getpass_with_description("Username", description));
                                init_curl_http_auth(slot->curl);
                                ret = HTTP_REAUTH;
                        }
                } else {
                        if (!curl_errorstr[0])
                                strlcpy(curl_errorstr,
                                        curl_easy_strerror(results.curl_result),
                                        sizeof(curl_errorstr));
                        ret = HTTP_ERROR;
                }
        } else {
                error("Unable to start HTTP request for %s", url);
                ret = HTTP_START_FAILED;
        }

        slot->local = NULL;
        curl_slist_free_all(headers);
        strbuf_release(&buf);

        return ret;
}

static int http_request_reauth(const char *url, void *result, int target,
                               int options)
{
        int ret = http_request(url, result, target, options);
        if (ret != HTTP_REAUTH)
                return ret;
        return http_request(url, result, target, options);
}

int http_get_strbuf(const char *url, struct strbuf *result, int options)
{
        return http_request_reauth(url, result, HTTP_REQUEST_STRBUF, options);
}

/*
 * Downloads an url and stores the result in the given file.
 *
 * If a previous interrupted download is detected (i.e. a previous temporary
 * file is still around) the download is resumed.
 */
static int http_get_file(const char *url, const char *filename, int options)
{
        int ret;
        struct strbuf tmpfile = STRBUF_INIT;
        FILE *result;

        strbuf_addf(&tmpfile, "%s.temp", filename);
        result = fopen(tmpfile.buf, "a");
        if (! result) {
                error("Unable to open local file %s", tmpfile.buf);
                ret = HTTP_ERROR;
                goto cleanup;
        }

        ret = http_request_reauth(url, result, HTTP_REQUEST_FILE, options);
        fclose(result);

        if ((ret == HTTP_OK) && move_temp_to_file(tmpfile.buf, filename))
                ret = HTTP_ERROR;
cleanup:
        strbuf_release(&tmpfile);
        return ret;
}

int http_error(const char *url, int ret)
{
        /* http_request has already handled HTTP_START_FAILED. */
        if (ret != HTTP_START_FAILED)
                error("%s while accessing %s", curl_errorstr, url);

        return ret;
}

int http_fetch_ref(const char *base, struct ref *ref)
{
        char *url;
        struct strbuf buffer = STRBUF_INIT;
        int ret = -1;

        url = quote_ref_url(base, ref->name);
        if (http_get_strbuf(url, &buffer, HTTP_NO_CACHE) == HTTP_OK) {
                strbuf_rtrim(&buffer);
                if (buffer.len == 40)
                        ret = get_sha1_hex(buffer.buf, ref->old_sha1);
                else if (!prefixcmp(buffer.buf, "ref: ")) {
                        ref->symref = xstrdup(buffer.buf + 5);
                        ret = 0;
                }
        }

        strbuf_release(&buffer);
        free(url);
        return ret;
}

/* Helpers for fetching packs */
static char *fetch_pack_index(unsigned char *sha1, const char *base_url)
{
        char *url, *tmp;
        struct strbuf buf = STRBUF_INIT;

        if (http_is_verbose)
                fprintf(stderr, "Getting index for pack %s\n", sha1_to_hex(sha1));

        end_url_with_slash(&buf, base_url);
        strbuf_addf(&buf, "objects/pack/pack-%s.idx", sha1_to_hex(sha1));
        url = strbuf_detach(&buf, NULL);

        strbuf_addf(&buf, "%s.temp", sha1_pack_index_name(sha1));
        tmp = strbuf_detach(&buf, NULL);

        if (http_get_file(url, tmp, 0) != HTTP_OK) {
                error("Unable to get pack index %s\n", url);
                free(tmp);
                tmp = NULL;
        }

        free(url);
        return tmp;
}

static int fetch_and_setup_pack_index(struct packed_git **packs_head,
        unsigned char *sha1, const char *base_url)
{
        struct packed_git *new_pack;
        char *tmp_idx = NULL;
        int ret;

        if (has_pack_index(sha1)) {
                new_pack = parse_pack_index(sha1, NULL);
                if (!new_pack)
                        return -1; /* parse_pack_index() already issued error message */
                goto add_pack;
        }

        tmp_idx = fetch_pack_index(sha1, base_url);
        if (!tmp_idx)
                return -1;

        new_pack = parse_pack_index(sha1, tmp_idx);
        if (!new_pack) {
                unlink(tmp_idx);
                free(tmp_idx);

                return -1; /* parse_pack_index() already issued error message */
        }

        ret = verify_pack_index(new_pack);
        if (!ret) {
                close_pack_index(new_pack);
                ret = move_temp_to_file(tmp_idx, sha1_pack_index_name(sha1));
        }
        free(tmp_idx);
        if (ret)
                return -1;

add_pack:
        new_pack->next = *packs_head;
        *packs_head = new_pack;
        return 0;
}

int http_get_info_packs(const char *base_url, struct packed_git **packs_head)
{
        int ret = 0, i = 0;
        char *url, *data;
        struct strbuf buf = STRBUF_INIT;
        unsigned char sha1[20];

        end_url_with_slash(&buf, base_url);
        strbuf_addstr(&buf, "objects/info/packs");
        url = strbuf_detach(&buf, NULL);

        ret = http_get_strbuf(url, &buf, HTTP_NO_CACHE);
        if (ret != HTTP_OK)
                goto cleanup;

        data = buf.buf;
        while (i < buf.len) {
                switch (data[i]) {
                case 'P':
                        i++;
                        if (i + 52 <= buf.len &&
                            !prefixcmp(data + i, " pack-") &&
                            !prefixcmp(data + i + 46, ".pack\n")) {
                                get_sha1_hex(data + i + 6, sha1);
                                fetch_and_setup_pack_index(packs_head, sha1,
                                                      base_url);
                                i += 51;
                                break;
                        }
                default:
                        while (i < buf.len && data[i] != '\n')
                                i++;
                }
                i++;
        }

cleanup:
        free(url);
        return ret;
}

void release_http_pack_request(struct http_pack_request *preq)
{
        if (preq->packfile != NULL) {
                fclose(preq->packfile);
                preq->packfile = NULL;
                preq->slot->local = NULL;
        }
        if (preq->range_header != NULL) {
                curl_slist_free_all(preq->range_header);
                preq->range_header = NULL;
        }
        preq->slot = NULL;
        free(preq->url);
}

int finish_http_pack_request(struct http_pack_request *preq)
{
        struct packed_git **lst;
        struct packed_git *p = preq->target;
        char *tmp_idx;
        struct child_process ip;
        const char *ip_argv[8];

        close_pack_index(p);

        fclose(preq->packfile);
        preq->packfile = NULL;
        preq->slot->local = NULL;

        lst = preq->lst;
        while (*lst != p)
                lst = &((*lst)->next);
        *lst = (*lst)->next;

        tmp_idx = xstrdup(preq->tmpfile);
        strcpy(tmp_idx + strlen(tmp_idx) - strlen(".pack.temp"),
               ".idx.temp");

        ip_argv[0] = "index-pack";
        ip_argv[1] = "-o";
        ip_argv[2] = tmp_idx;
        ip_argv[3] = preq->tmpfile;
        ip_argv[4] = NULL;

        memset(&ip, 0, sizeof(ip));
        ip.argv = ip_argv;
        ip.git_cmd = 1;
        ip.no_stdin = 1;
        ip.no_stdout = 1;

        if (run_command(&ip)) {
                unlink(preq->tmpfile);
                unlink(tmp_idx);
                free(tmp_idx);
                return -1;
        }

        unlink(sha1_pack_index_name(p->sha1));

        if (move_temp_to_file(preq->tmpfile, sha1_pack_name(p->sha1))
         || move_temp_to_file(tmp_idx, sha1_pack_index_name(p->sha1))) {
                free(tmp_idx);
                return -1;
        }

        install_packed_git(p);
        free(tmp_idx);
        return 0;
}

struct http_pack_request *new_http_pack_request(
        struct packed_git *target, const char *base_url)
{
        long prev_posn = 0;
        char range[RANGE_HEADER_SIZE];
        struct strbuf buf = STRBUF_INIT;
        struct http_pack_request *preq;

        preq = xcalloc(1, sizeof(*preq));
        preq->target = target;

        end_url_with_slash(&buf, base_url);
        strbuf_addf(&buf, "objects/pack/pack-%s.pack",
                sha1_to_hex(target->sha1));
        preq->url = strbuf_detach(&buf, NULL);

        snprintf(preq->tmpfile, sizeof(preq->tmpfile), "%s.temp",
                sha1_pack_name(target->sha1));
        preq->packfile = fopen(preq->tmpfile, "a");
        if (!preq->packfile) {
                error("Unable to open local file %s for pack",
                      preq->tmpfile);
                goto abort;
        }

        preq->slot = get_active_slot();
        preq->slot->local = preq->packfile;
        curl_easy_setopt(preq->slot->curl, CURLOPT_FILE, preq->packfile);
        curl_easy_setopt(preq->slot->curl, CURLOPT_WRITEFUNCTION, fwrite);
        curl_easy_setopt(preq->slot->curl, CURLOPT_URL, preq->url);
        curl_easy_setopt(preq->slot->curl, CURLOPT_HTTPHEADER,
                no_pragma_header);

        /*
         * If there is data present from a previous transfer attempt,
         * resume where it left off
         */
        prev_posn = ftell(preq->packfile);
        if (prev_posn>0) {
                if (http_is_verbose)
                        fprintf(stderr,
                                "Resuming fetch of pack %s at byte %ld\n",
                                sha1_to_hex(target->sha1), prev_posn);
                sprintf(range, "Range: bytes=%ld-", prev_posn);
                preq->range_header = curl_slist_append(NULL, range);
                curl_easy_setopt(preq->slot->curl, CURLOPT_HTTPHEADER,
                        preq->range_header);
        }

        return preq;

abort:
        free(preq->url);
        free(preq);
        return NULL;
}

/* Helpers for fetching objects (loose) */
static size_t fwrite_sha1_file(char *ptr, size_t eltsize, size_t nmemb,
                               void *data)
{
        unsigned char expn[4096];
        size_t size = eltsize * nmemb;
        int posn = 0;
        struct http_object_request *freq =
                (struct http_object_request *)data;
        do {
                ssize_t retval = xwrite(freq->localfile,
                                        (char *) ptr + posn, size - posn);
                if (retval < 0)
                        return posn;
                posn += retval;
        } while (posn < size);

        freq->stream.avail_in = size;
        freq->stream.next_in = (void *)ptr;
        do {
                freq->stream.next_out = expn;
                freq->stream.avail_out = sizeof(expn);
                freq->zret = git_inflate(&freq->stream, Z_SYNC_FLUSH);
                git_SHA1_Update(&freq->c, expn,
                                sizeof(expn) - freq->stream.avail_out);
        } while (freq->stream.avail_in && freq->zret == Z_OK);
        data_received++;
        return size;
}

struct http_object_request *new_http_object_request(const char *base_url,
        unsigned char *sha1)
{
        char *hex = sha1_to_hex(sha1);
        char *filename;
        char prevfile[PATH_MAX];
        int prevlocal;
        char prev_buf[PREV_BUF_SIZE];
        ssize_t prev_read = 0;
        long prev_posn = 0;
        char range[RANGE_HEADER_SIZE];
        struct curl_slist *range_header = NULL;
        struct http_object_request *freq;

        freq = xcalloc(1, sizeof(*freq));
        hashcpy(freq->sha1, sha1);
        freq->localfile = -1;

        filename = sha1_file_name(sha1);
        snprintf(freq->tmpfile, sizeof(freq->tmpfile),
                 "%s.temp", filename);

        snprintf(prevfile, sizeof(prevfile), "%s.prev", filename);
        unlink_or_warn(prevfile);
        rename(freq->tmpfile, prevfile);
        unlink_or_warn(freq->tmpfile);

        if (freq->localfile != -1)
                error("fd leakage in start: %d", freq->localfile);
        freq->localfile = open(freq->tmpfile,
                               O_WRONLY | O_CREAT | O_EXCL, 0666);
        /*
         * This could have failed due to the "lazy directory creation";
         * try to mkdir the last path component.
         */
        if (freq->localfile < 0 && errno == ENOENT) {
                char *dir = strrchr(freq->tmpfile, '/');
                if (dir) {
                        *dir = 0;
                        mkdir(freq->tmpfile, 0777);
                        *dir = '/';
                }
                freq->localfile = open(freq->tmpfile,
                                       O_WRONLY | O_CREAT | O_EXCL, 0666);
        }

        if (freq->localfile < 0) {
                error("Couldn't create temporary file %s: %s",
                      freq->tmpfile, strerror(errno));
                goto abort;
        }

        git_inflate_init(&freq->stream);

        git_SHA1_Init(&freq->c);

        freq->url = get_remote_object_url(base_url, hex, 0);

        /*
         * If a previous temp file is present, process what was already
         * fetched.
         */
        prevlocal = open(prevfile, O_RDONLY);
        if (prevlocal != -1) {
                do {
                        prev_read = xread(prevlocal, prev_buf, PREV_BUF_SIZE);
                        if (prev_read>0) {
                                if (fwrite_sha1_file(prev_buf,
                                                     1,
                                                     prev_read,
                                                     freq) == prev_read) {
                                        prev_posn += prev_read;
                                } else {
                                        prev_read = -1;
                                }
                        }
                } while (prev_read > 0);
                close(prevlocal);
        }
        unlink_or_warn(prevfile);

        /*
         * Reset inflate/SHA1 if there was an error reading the previous temp
         * file; also rewind to the beginning of the local file.
         */
        if (prev_read == -1) {
                memset(&freq->stream, 0, sizeof(freq->stream));
                git_inflate_init(&freq->stream);
                git_SHA1_Init(&freq->c);
                if (prev_posn>0) {
                        prev_posn = 0;
                        lseek(freq->localfile, 0, SEEK_SET);
                        if (ftruncate(freq->localfile, 0) < 0) {
                                error("Couldn't truncate temporary file %s: %s",
                                          freq->tmpfile, strerror(errno));
                                goto abort;
                        }
                }
        }

        freq->slot = get_active_slot();

        curl_easy_setopt(freq->slot->curl, CURLOPT_FILE, freq);
        curl_easy_setopt(freq->slot->curl, CURLOPT_WRITEFUNCTION, fwrite_sha1_file);
        curl_easy_setopt(freq->slot->curl, CURLOPT_ERRORBUFFER, freq->errorstr);
        curl_easy_setopt(freq->slot->curl, CURLOPT_URL, freq->url);
        curl_easy_setopt(freq->slot->curl, CURLOPT_HTTPHEADER, no_pragma_header);

        /*
         * If we have successfully processed data from a previous fetch
         * attempt, only fetch the data we don't already have.
         */
        if (prev_posn>0) {
                if (http_is_verbose)
                        fprintf(stderr,
                                "Resuming fetch of object %s at byte %ld\n",
                                hex, prev_posn);
                sprintf(range, "Range: bytes=%ld-", prev_posn);
                range_header = curl_slist_append(range_header, range);
                curl_easy_setopt(freq->slot->curl,
                                 CURLOPT_HTTPHEADER, range_header);
        }

        return freq;

abort:
        free(freq->url);
        free(freq);
        return NULL;
}

void process_http_object_request(struct http_object_request *freq)
{
        if (freq->slot == NULL)
                return;
        freq->curl_result = freq->slot->curl_result;
        freq->http_code = freq->slot->http_code;
        freq->slot = NULL;
}

int finish_http_object_request(struct http_object_request *freq)
{
        struct stat st;

        close(freq->localfile);
        freq->localfile = -1;

        process_http_object_request(freq);

        if (freq->http_code == 416) {
                warning("requested range invalid; we may already have all the data.");
        } else if (freq->curl_result != CURLE_OK) {
                if (stat(freq->tmpfile, &st) == 0)
                        if (st.st_size == 0)
                                unlink_or_warn(freq->tmpfile);
                return -1;
        }

        git_inflate_end(&freq->stream);
        git_SHA1_Final(freq->real_sha1, &freq->c);
        if (freq->zret != Z_STREAM_END) {
                unlink_or_warn(freq->tmpfile);
                return -1;
        }
        if (hashcmp(freq->sha1, freq->real_sha1)) {
                unlink_or_warn(freq->tmpfile);
                return -1;
        }
        freq->rename =
                move_temp_to_file(freq->tmpfile, sha1_file_name(freq->sha1));

        return freq->rename;
}

void abort_http_object_request(struct http_object_request *freq)
{
        unlink_or_warn(freq->tmpfile);

        release_http_object_request(freq);
}

void release_http_object_request(struct http_object_request *freq)
{
        if (freq->localfile != -1) {
                close(freq->localfile);
                freq->localfile = -1;
        }
        if (freq->url != NULL) {
                free(freq->url);
                freq->url = NULL;
        }
        if (freq->slot != NULL) {
                freq->slot->callback_func = NULL;
                freq->slot->callback_data = NULL;
                release_active_slot(freq->slot);
                freq->slot = NULL;
        }
}