#include "cache.h"
#include "config.h"
#include "repository.h"
#include "refs.h"
#include "pkt-line.h"
#include "object.h"
#include "tag.h"
#include "exec-cmd.h"
#include "run-command.h"
#include "string-list.h"
#include "url.h"
#include "argv-array.h"
#include "packfile.h"
#include "object-store.h"
#include "protocol.h"

static const char content_type[] = "Content-Type";
static const char content_length[] = "Content-Length";
static const char last_modified[] = "Last-Modified";
static int getanyfile = 1;
static unsigned long max_request_buffer = 10 * 1024 * 1024;

static struct string_list *query_params;

struct rpc_service {
        const char *name;
        const char *config_name;
        unsigned buffer_input : 1;
        signed enabled : 2;
};

static struct rpc_service rpc_service[] = {
        { "upload-pack", "uploadpack", 1, 1 },
        { "receive-pack", "receivepack", 0, -1 },
};

static struct string_list *get_parameters(void)
{
        if (!query_params) {
                const char *query = getenv("QUERY_STRING");

                query_params = xcalloc(1, sizeof(*query_params));
                while (query && *query) {
                        char *name = url_decode_parameter_name(&query);
                        char *value = url_decode_parameter_value(&query);
                        struct string_list_item *i;

                        i = string_list_lookup(query_params, name);
                        if (!i)
                                i = string_list_insert(query_params, name);
                        else
                                free(i->util);
                        i->util = value;
                }
        }
        return query_params;
}

static const char *get_parameter(const char *name)
{
        struct string_list_item *i;
        i = string_list_lookup(get_parameters(), name);
        return i ? i->util : NULL;
}

__attribute__((format (printf, 2, 3)))
static void format_write(int fd, const char *fmt, ...)
{
        static char buffer[1024];

        va_list args;
        unsigned n;

        va_start(args, fmt);
        n = vsnprintf(buffer, sizeof(buffer), fmt, args);
        va_end(args);
        if (n >= sizeof(buffer))
                die("protocol error: impossibly long line");

        write_or_die(fd, buffer, n);
}

static void http_status(struct strbuf *hdr, unsigned code, const char *msg)
{
        strbuf_addf(hdr, "Status: %u %s\r\n", code, msg);
}

static void hdr_str(struct strbuf *hdr, const char *name, const char *value)
{
        strbuf_addf(hdr, "%s: %s\r\n", name, value);
}

static void hdr_int(struct strbuf *hdr, const char *name, uintmax_t value)
{
        strbuf_addf(hdr, "%s: %" PRIuMAX "\r\n", name, value);
}

static void hdr_date(struct strbuf *hdr, const char *name, timestamp_t when)
{
        const char *value = show_date(when, 0, DATE_MODE(RFC2822));
        hdr_str(hdr, name, value);
}

static void hdr_nocache(struct strbuf *hdr)
{
        hdr_str(hdr, "Expires", "Fri, 01 Jan 1980 00:00:00 GMT");
        hdr_str(hdr, "Pragma", "no-cache");
        hdr_str(hdr, "Cache-Control", "no-cache, max-age=0, must-revalidate");
}

static void hdr_cache_forever(struct strbuf *hdr)
{
        timestamp_t now = time(NULL);
        hdr_date(hdr, "Date", now);
        hdr_date(hdr, "Expires", now + 31536000);
        hdr_str(hdr, "Cache-Control", "public, max-age=31536000");
}

static void end_headers(struct strbuf *hdr)
{
        strbuf_add(hdr, "\r\n", 2);
        write_or_die(1, hdr->buf, hdr->len);
        strbuf_release(hdr);
}

__attribute__((format (printf, 2, 3)))
static NORETURN void not_found(struct strbuf *hdr, const char *err, ...)
{
        va_list params;

        http_status(hdr, 404, "Not Found");
        hdr_nocache(hdr);
        end_headers(hdr);

        va_start(params, err);
        if (err && *err)
                vfprintf(stderr, err, params);
        va_end(params);
        exit(0);
}

__attribute__((format (printf, 2, 3)))
static NORETURN void forbidden(struct strbuf *hdr, const char *err, ...)
{
        va_list params;

        http_status(hdr, 403, "Forbidden");
        hdr_nocache(hdr);
        end_headers(hdr);

        va_start(params, err);
        if (err && *err)
                vfprintf(stderr, err, params);
        va_end(params);
        exit(0);
}

static void select_getanyfile(struct strbuf *hdr)
{
        if (!getanyfile)
                forbidden(hdr, "Unsupported service: getanyfile");
}

static void send_strbuf(struct strbuf *hdr,
                        const char *type, struct strbuf *buf)
{
        hdr_int(hdr, content_length, buf->len);
        hdr_str(hdr, content_type, type);
        end_headers(hdr);
        write_or_die(1, buf->buf, buf->len);
}

static void send_local_file(struct strbuf *hdr, const char *the_type,
                                const char *name)
{
        char *p = git_pathdup("%s", name);
        size_t buf_alloc = 8192;
        char *buf = xmalloc(buf_alloc);
        int fd;
        struct stat sb;

        fd = open(p, O_RDONLY);
        if (fd < 0)
                not_found(hdr, "Cannot open '%s': %s", p, strerror(errno));
        if (fstat(fd, &sb) < 0)
                die_errno("Cannot stat '%s'", p);

        hdr_int(hdr, content_length, sb.st_size);
        hdr_str(hdr, content_type, the_type);
        hdr_date(hdr, last_modified, sb.st_mtime);
        end_headers(hdr);

        for (;;) {
                ssize_t n = xread(fd, buf, buf_alloc);
                if (n < 0)
                        die_errno("Cannot read '%s'", p);
                if (!n)
                        break;
                write_or_die(1, buf, n);
        }
        close(fd);
        free(buf);
        free(p);
}

static void get_text_file(struct strbuf *hdr, char *name)
{
        select_getanyfile(hdr);
        hdr_nocache(hdr);
        send_local_file(hdr, "text/plain", name);
}

static void get_loose_object(struct strbuf *hdr, char *name)
{
        select_getanyfile(hdr);
        hdr_cache_forever(hdr);
        send_local_file(hdr, "application/x-git-loose-object", name);
}

static void get_pack_file(struct strbuf *hdr, char *name)
{
        select_getanyfile(hdr);
        hdr_cache_forever(hdr);
        send_local_file(hdr, "application/x-git-packed-objects", name);
}

static void get_idx_file(struct strbuf *hdr, char *name)
{
        select_getanyfile(hdr);
        hdr_cache_forever(hdr);
        send_local_file(hdr, "application/x-git-packed-objects-toc", name);
}

static void http_config(void)
{
        int i, value = 0;
        struct strbuf var = STRBUF_INIT;

        git_config_get_bool("http.getanyfile", &getanyfile);
        git_config_get_ulong("http.maxrequestbuffer", &max_request_buffer);

        for (i = 0; i < ARRAY_SIZE(rpc_service); i++) {
                struct rpc_service *svc = &rpc_service[i];
                strbuf_addf(&var, "http.%s", svc->config_name);
                if (!git_config_get_bool(var.buf, &value))
                        svc->enabled = value;
                strbuf_reset(&var);
        }

        strbuf_release(&var);
}

static struct rpc_service *select_service(struct strbuf *hdr, const char *name)
{
        const char *svc_name;
        struct rpc_service *svc = NULL;
        int i;

        if (!skip_prefix(name, "git-", &svc_name))
                forbidden(hdr, "Unsupported service: '%s'", name);

        for (i = 0; i < ARRAY_SIZE(rpc_service); i++) {
                struct rpc_service *s = &rpc_service[i];
                if (!strcmp(s->name, svc_name)) {
                        svc = s;
                        break;
                }
        }

        if (!svc)
                forbidden(hdr, "Unsupported service: '%s'", name);

        if (svc->enabled < 0) {
                const char *user = getenv("REMOTE_USER");
                svc->enabled = (user && *user) ? 1 : 0;
        }
        if (!svc->enabled)
                forbidden(hdr, "Service not enabled: '%s'", svc->name);
        return svc;
}

static void write_to_child(int out, const unsigned char *buf, ssize_t len, const char *prog_name)
{
        if (write_in_full(out, buf, len) < 0)
                die("unable to write to '%s'", prog_name);
}

/*
 * This is basically strbuf_read(), except that if we
 * hit max_request_buffer we die (we'd rather reject a
 * maliciously large request than chew up infinite memory).
 */
static ssize_t read_request_eof(int fd, unsigned char **out)
{
        size_t len = 0, alloc = 8192;
        unsigned char *buf = xmalloc(alloc);

        if (max_request_buffer < alloc)
                max_request_buffer = alloc;

        while (1) {
                ssize_t cnt;

                cnt = read_in_full(fd, buf + len, alloc - len);
                if (cnt < 0) {
                        free(buf);
                        return -1;
                }

                /* partial read from read_in_full means we hit EOF */
                len += cnt;
                if (len < alloc) {
                        *out = buf;
                        return len;
                }

                /* otherwise, grow and try again (if we can) */
                if (alloc == max_request_buffer)
                        die("request was larger than our maximum size (%lu);"
                            " try setting GIT_HTTP_MAX_REQUEST_BUFFER",
                            max_request_buffer);

                alloc = alloc_nr(alloc);
                if (alloc > max_request_buffer)
                        alloc = max_request_buffer;
                REALLOC_ARRAY(buf, alloc);
        }
}

static ssize_t read_request_fixed_len(int fd, ssize_t req_len, unsigned char **out)
{
        unsigned char *buf = NULL;
        ssize_t cnt = 0;

        if (max_request_buffer < req_len) {
                die("request was larger than our maximum size (%lu): "
                    "%" PRIuMAX "; try setting GIT_HTTP_MAX_REQUEST_BUFFER",
                    max_request_buffer, (uintmax_t)req_len);
        }

        buf = xmalloc(req_len);
        cnt = read_in_full(fd, buf, req_len);
        if (cnt < 0) {
                free(buf);
                return -1;
        }
        *out = buf;
        return cnt;
}

static ssize_t get_content_length(void)
{
        ssize_t val = -1;
        const char *str = getenv("CONTENT_LENGTH");

        if (str && !git_parse_ssize_t(str, &val))
                die("failed to parse CONTENT_LENGTH: %s", str);
        return val;
}

static ssize_t read_request(int fd, unsigned char **out, ssize_t req_len)
{
        if (req_len < 0)
                return read_request_eof(fd, out);
        else
                return read_request_fixed_len(fd, req_len, out);
}

static void inflate_request(const char *prog_name, int out, int buffer_input, ssize_t req_len)
{
        git_zstream stream;
        unsigned char *full_request = NULL;
        unsigned char in_buf[8192];
        unsigned char out_buf[8192];
        unsigned long cnt = 0;

        memset(&stream, 0, sizeof(stream));
        git_inflate_init_gzip_only(&stream);

        while (1) {
                ssize_t n;

                if (buffer_input) {
                        if (full_request)
                                n = 0; /* nothing left to read */
                        else
                                n = read_request(0, &full_request, req_len);
                        stream.next_in = full_request;
                } else {
                        n = xread(0, in_buf, sizeof(in_buf));
                        stream.next_in = in_buf;
                }

                if (n <= 0)
                        die("request ended in the middle of the gzip stream");
                stream.avail_in = n;

                while (0 < stream.avail_in) {
                        int ret;

                        stream.next_out = out_buf;
                        stream.avail_out = sizeof(out_buf);

                        ret = git_inflate(&stream, Z_NO_FLUSH);
                        if (ret != Z_OK && ret != Z_STREAM_END)
                                die("zlib error inflating request, result %d", ret);

                        n = stream.total_out - cnt;
                        write_to_child(out, out_buf, stream.total_out - cnt, prog_name);
                        cnt = stream.total_out;

                        if (ret == Z_STREAM_END)
                                goto done;
                }
        }

done:
        git_inflate_end(&stream);
        close(out);
        free(full_request);
}

static void copy_request(const char *prog_name, int out, ssize_t req_len)
{
        unsigned char *buf;
        ssize_t n = read_request(0, &buf, req_len);
        if (n < 0)
                die_errno("error reading request body");
        write_to_child(out, buf, n, prog_name);
        close(out);
        free(buf);
}

static void run_service(const char **argv, int buffer_input)
{
        const char *encoding = getenv("HTTP_CONTENT_ENCODING");
        const char *user = getenv("REMOTE_USER");
        const char *host = getenv("REMOTE_ADDR");
        int gzipped_request = 0;
        struct child_process cld = CHILD_PROCESS_INIT;
        ssize_t req_len = get_content_length();

        if (encoding && !strcmp(encoding, "gzip"))
                gzipped_request = 1;
        else if (encoding && !strcmp(encoding, "x-gzip"))
                gzipped_request = 1;

        if (!user || !*user)
                user = "anonymous";
        if (!host || !*host)
                host = "(none)";

        if (!getenv("GIT_COMMITTER_NAME"))
                argv_array_pushf(&cld.env_array, "GIT_COMMITTER_NAME=%s", user);
        if (!getenv("GIT_COMMITTER_EMAIL"))
                argv_array_pushf(&cld.env_array,
                                 "GIT_COMMITTER_EMAIL=%s@http.%s", user, host);

        cld.argv = argv;
        if (buffer_input || gzipped_request)
                cld.in = -1;
        cld.git_cmd = 1;
        if (start_command(&cld))
                exit(1);

        close(1);
        if (gzipped_request)
                inflate_request(argv[0], cld.in, buffer_input, req_len);
        else if (buffer_input)
                copy_request(argv[0], cld.in, req_len);
        else
                close(0);

        if (finish_command(&cld))
                exit(1);
}

static int show_text_ref(const char *name, const struct object_id *oid,
                         int flag, void *cb_data)
{
        const char *name_nons = strip_namespace(name);
        struct strbuf *buf = cb_data;
        struct object *o = parse_object(oid);
        if (!o)
                return 0;

        strbuf_addf(buf, "%s\t%s\n", oid_to_hex(oid), name_nons);
        if (o->type == OBJ_TAG) {
                o = deref_tag(o, name, 0);
                if (!o)
                        return 0;
                strbuf_addf(buf, "%s\t%s^{}\n", oid_to_hex(&o->oid),
                            name_nons);
        }
        return 0;
}

static void get_info_refs(struct strbuf *hdr, char *arg)
{
        const char *service_name = get_parameter("service");
        struct strbuf buf = STRBUF_INIT;

        hdr_nocache(hdr);

        if (service_name) {
                const char *argv[] = {NULL /* service name */,
                        "--stateless-rpc", "--advertise-refs",
                        ".", NULL};
                struct rpc_service *svc = select_service(hdr, service_name);

                strbuf_addf(&buf, "application/x-git-%s-advertisement",
                        svc->name);
                hdr_str(hdr, content_type, buf.buf);
                end_headers(hdr);


                if (determine_protocol_version_server() != protocol_v2) {
                        packet_write_fmt(1, "# service=git-%s\n", svc->name);
                        packet_flush(1);
                }

                argv[0] = svc->name;
                run_service(argv, 0);

        } else {
                select_getanyfile(hdr);
                for_each_namespaced_ref(show_text_ref, &buf);
                send_strbuf(hdr, "text/plain", &buf);
        }
        strbuf_release(&buf);
}

static int show_head_ref(const char *refname, const struct object_id *oid,
                         int flag, void *cb_data)
{
        struct strbuf *buf = cb_data;

        if (flag & REF_ISSYMREF) {
                const char *target = resolve_ref_unsafe(refname,
                                                        RESOLVE_REF_READING,
                                                        NULL, NULL);

                if (target)
                        strbuf_addf(buf, "ref: %s\n", strip_namespace(target));
        } else {
                strbuf_addf(buf, "%s\n", oid_to_hex(oid));
        }

        return 0;
}

static void get_head(struct strbuf *hdr, char *arg)
{
        struct strbuf buf = STRBUF_INIT;

        select_getanyfile(hdr);
        head_ref_namespaced(show_head_ref, &buf);
        send_strbuf(hdr, "text/plain", &buf);
        strbuf_release(&buf);
}

static void get_info_packs(struct strbuf *hdr, char *arg)
{
        size_t objdirlen = strlen(get_object_directory());
        struct strbuf buf = STRBUF_INIT;
        struct packed_git *p;
        size_t cnt = 0;

        select_getanyfile(hdr);
        for (p = get_packed_git(the_repository); p; p = p->next) {
                if (p->pack_local)
                        cnt++;
        }

        strbuf_grow(&buf, cnt * 53 + 2);
        for (p = get_packed_git(the_repository); p; p = p->next) {
                if (p->pack_local)
                        strbuf_addf(&buf, "P %s\n", p->pack_name + objdirlen + 6);
        }
        strbuf_addch(&buf, '\n');

        hdr_nocache(hdr);
        send_strbuf(hdr, "text/plain; charset=utf-8", &buf);
        strbuf_release(&buf);
}

static void check_content_type(struct strbuf *hdr, const char *accepted_type)
{
        const char *actual_type = getenv("CONTENT_TYPE");

        if (!actual_type)
                actual_type = "";

        if (strcmp(actual_type, accepted_type)) {
                http_status(hdr, 415, "Unsupported Media Type");
                hdr_nocache(hdr);
                end_headers(hdr);
                format_write(1,
                        "Expected POST with Content-Type '%s',"
                        " but received '%s' instead.\n",
                        accepted_type, actual_type);
                exit(0);
        }
}

static void service_rpc(struct strbuf *hdr, char *service_name)
{
        const char *argv[] = {NULL, "--stateless-rpc", ".", NULL};
        struct rpc_service *svc = select_service(hdr, service_name);
        struct strbuf buf = STRBUF_INIT;

        strbuf_reset(&buf);
        strbuf_addf(&buf, "application/x-git-%s-request", svc->name);
        check_content_type(hdr, buf.buf);

        hdr_nocache(hdr);

        strbuf_reset(&buf);
        strbuf_addf(&buf, "application/x-git-%s-result", svc->name);
        hdr_str(hdr, content_type, buf.buf);

        end_headers(hdr);

        argv[0] = svc->name;
        run_service(argv, svc->buffer_input);
        strbuf_release(&buf);
}

static int dead;
static NORETURN void die_webcgi(const char *err, va_list params)
{
        if (dead <= 1) {
                struct strbuf hdr = STRBUF_INIT;

                vreportf("fatal: ", err, params);

                http_status(&hdr, 500, "Internal Server Error");
                hdr_nocache(&hdr);
                end_headers(&hdr);
        }
        exit(0); /* we successfully reported a failure ;-) */
}

static int die_webcgi_recursing(void)
{
        return dead++ > 1;
}

static char* getdir(void)
{
        struct strbuf buf = STRBUF_INIT;
        char *pathinfo = getenv("PATH_INFO");
        char *root = getenv("GIT_PROJECT_ROOT");
        char *path = getenv("PATH_TRANSLATED");

        if (root && *root) {
                if (!pathinfo || !*pathinfo)
                        die("GIT_PROJECT_ROOT is set but PATH_INFO is not");
                if (daemon_avoid_alias(pathinfo))
                        die("'%s': aliased", pathinfo);
                end_url_with_slash(&buf, root);
                if (pathinfo[0] == '/')
                        pathinfo++;
                strbuf_addstr(&buf, pathinfo);
                return strbuf_detach(&buf, NULL);
        } else if (path && *path) {
                return xstrdup(path);
        } else
                die("No GIT_PROJECT_ROOT or PATH_TRANSLATED from server");
        return NULL;
}

static struct service_cmd {
        const char *method;
        const char *pattern;
        void (*imp)(struct strbuf *, char *);
} services[] = {
        {"GET", "/HEAD$", get_head},
        {"GET", "/info/refs$", get_info_refs},
        {"GET", "/objects/info/alternates$", get_text_file},
        {"GET", "/objects/info/http-alternates$", get_text_file},
        {"GET", "/objects/info/packs$", get_info_packs},
        {"GET", "/objects/[0-9a-f]{2}/[0-9a-f]{38}$", get_loose_object},
        {"GET", "/objects/pack/pack-[0-9a-f]{40}\\.pack$", get_pack_file},
        {"GET", "/objects/pack/pack-[0-9a-f]{40}\\.idx$", get_idx_file},

        {"POST", "/git-upload-pack$", service_rpc},
        {"POST", "/git-receive-pack$", service_rpc}
};

static int bad_request(struct strbuf *hdr, const struct service_cmd *c)
{
        const char *proto = getenv("SERVER_PROTOCOL");

        if (proto && !strcmp(proto, "HTTP/1.1")) {
                http_status(hdr, 405, "Method Not Allowed");
                hdr_str(hdr, "Allow",
                        !strcmp(c->method, "GET") ? "GET, HEAD" : c->method);
        } else
                http_status(hdr, 400, "Bad Request");
        hdr_nocache(hdr);
        end_headers(hdr);
        return 0;
}

int cmd_main(int argc, const char **argv)
{
        char *method = getenv("REQUEST_METHOD");
        char *dir;
        struct service_cmd *cmd = NULL;
        char *cmd_arg = NULL;
        int i;
        struct strbuf hdr = STRBUF_INIT;

        set_die_routine(die_webcgi);
        set_die_is_recursing_routine(die_webcgi_recursing);

        if (!method)
                die("No REQUEST_METHOD from server");
        if (!strcmp(method, "HEAD"))
                method = "GET";
        dir = getdir();

        for (i = 0; i < ARRAY_SIZE(services); i++) {
                struct service_cmd *c = &services[i];
                regex_t re;
                regmatch_t out[1];

                if (regcomp(&re, c->pattern, REG_EXTENDED))
                        die("Bogus regex in service table: %s", c->pattern);
                if (!regexec(&re, dir, 1, out, 0)) {
                        size_t n;

                        if (strcmp(method, c->method))
                                return bad_request(&hdr, c);

                        cmd = c;
                        n = out[0].rm_eo - out[0].rm_so;
                        cmd_arg = xmemdupz(dir + out[0].rm_so + 1, n - 1);
                        dir[out[0].rm_so] = 0;
                        break;
                }
                regfree(&re);
        }

        if (!cmd)
                not_found(&hdr, "Request not supported: '%s'", dir);

        setup_path();
        if (!enter_repo(dir, 0))
                not_found(&hdr, "Not a git repository: '%s'", dir);
        if (!getenv("GIT_HTTP_EXPORT_ALL") &&
            access("git-daemon-export-ok", F_OK) )
                not_found(&hdr, "Repository not exported: '%s'", dir);

        http_config();
        max_request_buffer = git_env_ulong("GIT_HTTP_MAX_REQUEST_BUFFER",
                                           max_request_buffer);

        cmd->imp(&hdr, cmd_arg);
        return 0;
}