http*: add helper methods for fetching packs

[thirdparty/git.git] / http.c

#include "http.h"
#include "pack.h"

int data_received;
int active_requests;
int http_is_verbose;

#ifdef USE_CURL_MULTI
static int max_requests = -1;
static CURLM *curlm;
#endif
#ifndef NO_CURL_EASY_DUPHANDLE
static CURL *curl_default;
#endif
char curl_errorstr[CURL_ERROR_SIZE];

static int curl_ssl_verify = -1;
static const char *ssl_cert;
#if LIBCURL_VERSION_NUM >= 0x070902
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 char *user_name, *user_pass;

static struct curl_slist *pragma_header;

struct curl_slist *no_pragma_header;

static struct active_request_slot *active_queue_head;

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

static void finish_active_slot(struct active_request_slot *slot);

#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 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 >= 0x070902
	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);
#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);

	/* 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(getpass("Password: "));
		strbuf_addf(&up, "%s:%s", user_name, user_pass);
		curl_easy_setopt(result, CURLOPT_USERPWD,
				 strbuf_detach(&up, NULL));
	}
}

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

	init_curl_http_auth(result);

	if (ssl_cert != NULL)
		curl_easy_setopt(result, CURLOPT_SSLCERT, ssl_cert);
#if LIBCURL_VERSION_NUM >= 0x070902
	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 (getenv("GIT_CURL_VERBOSE"))
		curl_easy_setopt(result, CURLOPT_VERBOSE, 1);

	curl_easy_setopt(result, CURLOPT_USERAGENT, GIT_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)
{
	char *at, *colon, *cp, *slash;
	int len;

	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)
		return; /* No credentials */
	if (!colon || at <= colon) {
		/* Only username */
		len = at - cp;
		user_name = xmalloc(len + 1);
		memcpy(user_name, cp, len);
		user_name[len] = '\0';
		user_pass = NULL;
	} else {
		len = colon - cp;
		user_name = xmalloc(len + 1);
		memcpy(user_name, cp, len);
		user_name[len] = '\0';
		len = at - (colon + 1);
		user_pass = xmalloc(len + 1);
		memcpy(user_pass, colon + 1, len);
		user_pass[len] = '\0';
	}
}

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)
{
	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 >= 0x070902
	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");

	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;

#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 (remote && remote->url && remote->url[0])
		http_auth_init(remote->url[0]);

#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;
	}
}

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
	}

	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_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_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_easy_cleanup(slot->curl);
			slot->curl = NULL;
		}
		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;
}

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

static 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 void end_url_with_slash(struct strbuf *buf, const char *url)
{
	strbuf_addstr(buf, url);
	if (buf->len && buf->buf[buf->len - 1] != '/')
		strbuf_addstr(buf, "/");
}

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);
}

/* 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
			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;
}

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

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(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\n", 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 int fetch_pack_index(unsigned char *sha1, const char *base_url)
{
	int ret = 0;
	char *hex = xstrdup(sha1_to_hex(sha1));
	char *filename;
	char *url;
	struct strbuf buf = STRBUF_INIT;

	/* Don't use the index if the pack isn't there */
	end_url_with_slash(&buf, base_url);
	strbuf_addf(&buf, "objects/pack/pack-%s.pack", hex);
	url = strbuf_detach(&buf, 0);

	if (http_get_strbuf(url, NULL, 0)) {
		ret = error("Unable to verify pack %s is available",
			    hex);
		goto cleanup;
	}

	if (has_pack_index(sha1)) {
		ret = 0;
		goto cleanup;
	}

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

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

	filename = sha1_pack_index_name(sha1);
	if (http_get_file(url, filename, 0) != HTTP_OK)
		ret = error("Unable to get pack index %s\n", url);

cleanup:
	free(hex);
	free(url);
	return ret;
}

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

	if (fetch_pack_index(sha1, base_url))
		return -1;

	new_pack = parse_pack_index(sha1);
	if (!new_pack)
		return -1; /* parse_pack_index() already issued error message */
	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)
{
	int ret;
	struct packed_git **lst;

	preq->target->pack_size = ftell(preq->packfile);

	if (preq->packfile != NULL) {
		fclose(preq->packfile);
		preq->packfile = NULL;
		preq->slot->local = NULL;
	}

	ret = move_temp_to_file(preq->tmpfile, preq->filename);
	if (ret)
		return ret;

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

	if (verify_pack(preq->target))
		return -1;
	install_packed_git(preq->target);

	return 0;
}

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

	preq = xmalloc(sizeof(*preq));
	preq->target = target;
	preq->range_header = NULL;

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

	filename = sha1_pack_name(target->sha1);
	snprintf(preq->filename, sizeof(preq->filename), "%s", filename);
	snprintf(preq->tmpfile, sizeof(preq->tmpfile), "%s.temp", filename);
	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, 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(filename);
	return NULL;
}