#include "git-compat-util.h"
#include "cache.h"
#include "pkt-line.h"
#include "quote.h"
#include "refs.h"
#include "run-command.h"

static char *server_capabilities;

static int check_ref(const char *name, int len, unsigned int flags)
{
        if (!flags)
                return 1;

        if (len < 5 || memcmp(name, "refs/", 5))
                return 0;

        /* Skip the "refs/" part */
        name += 5;
        len -= 5;

        /* REF_NORMAL means that we don't want the magic fake tag refs */
        if ((flags & REF_NORMAL) && check_ref_format(name) < 0)
                return 0;

        /* REF_HEADS means that we want regular branch heads */
        if ((flags & REF_HEADS) && !memcmp(name, "heads/", 6))
                return 1;

        /* REF_TAGS means that we want tags */
        if ((flags & REF_TAGS) && !memcmp(name, "tags/", 5))
                return 1;

        /* All type bits clear means that we are ok with anything */
        return !(flags & ~REF_NORMAL);
}

/*
 * Read all the refs from the other end
 */
struct ref **get_remote_heads(int in, struct ref **list,
                              int nr_match, char **match,
                              unsigned int flags)
{
        *list = NULL;
        for (;;) {
                struct ref *ref;
                unsigned char old_sha1[20];
                static char buffer[1000];
                char *name;
                int len, name_len;

                len = packet_read_line(in, buffer, sizeof(buffer));
                if (!len)
                        break;
                if (buffer[len-1] == '\n')
                        buffer[--len] = 0;

                if (len < 42 || get_sha1_hex(buffer, old_sha1) || buffer[40] != ' ')
                        die("protocol error: expected sha/ref, got '%s'", buffer);
                name = buffer + 41;

                name_len = strlen(name);
                if (len != name_len + 41) {
                        if (server_capabilities)
                                free(server_capabilities);
                        server_capabilities = xstrdup(name + name_len + 1);
                }

                if (!check_ref(name, name_len, flags))
                        continue;
                if (nr_match && !path_match(name, nr_match, match))
                        continue;
                ref = xcalloc(1, sizeof(*ref) + len - 40);
                hashcpy(ref->old_sha1, old_sha1);
                memcpy(ref->name, buffer + 41, len - 40);
                *list = ref;
                list = &ref->next;
        }
        return list;
}

int server_supports(const char *feature)
{
        return server_capabilities &&
                strstr(server_capabilities, feature) != NULL;
}

int get_ack(int fd, unsigned char *result_sha1)
{
        static char line[1000];
        int len = packet_read_line(fd, line, sizeof(line));

        if (!len)
                die("git-fetch-pack: expected ACK/NAK, got EOF");
        if (line[len-1] == '\n')
                line[--len] = 0;
        if (!strcmp(line, "NAK"))
                return 0;
        if (!prefixcmp(line, "ACK ")) {
                if (!get_sha1_hex(line+4, result_sha1)) {
                        if (strstr(line+45, "continue"))
                                return 2;
                        return 1;
                }
        }
        die("git-fetch_pack: expected ACK/NAK, got '%s'", line);
}

int path_match(const char *path, int nr, char **match)
{
        int i;
        int pathlen = strlen(path);

        for (i = 0; i < nr; i++) {
                char *s = match[i];
                int len = strlen(s);

                if (!len || len > pathlen)
                        continue;
                if (memcmp(path + pathlen - len, s, len))
                        continue;
                if (pathlen > len && path[pathlen - len - 1] != '/')
                        continue;
                *s = 0;
                return (i + 1);
        }
        return 0;
}

struct refspec {
        char *src;
        char *dst;
        char force;
};

/*
 * A:B means fast forward remote B with local A.
 * +A:B means overwrite remote B with local A.
 * +A is a shorthand for +A:A.
 * A is a shorthand for A:A.
 * :B means delete remote B.
 */
static struct refspec *parse_ref_spec(int nr_refspec, char **refspec)
{
        int i;
        struct refspec *rs = xcalloc(sizeof(*rs), (nr_refspec + 1));
        for (i = 0; i < nr_refspec; i++) {
                char *sp, *dp, *ep;
                sp = refspec[i];
                if (*sp == '+') {
                        rs[i].force = 1;
                        sp++;
                }
                ep = strchr(sp, ':');
                if (ep) {
                        dp = ep + 1;
                        *ep = 0;
                }
                else
                        dp = sp;
                rs[i].src = sp;
                rs[i].dst = dp;
        }
        rs[nr_refspec].src = rs[nr_refspec].dst = NULL;
        return rs;
}

static int count_refspec_match(const char *pattern,
                               struct ref *refs,
                               struct ref **matched_ref)
{
        int patlen = strlen(pattern);
        struct ref *matched_weak = NULL;
        struct ref *matched = NULL;
        int weak_match = 0;
        int match = 0;

        for (weak_match = match = 0; refs; refs = refs->next) {
                char *name = refs->name;
                int namelen = strlen(name);
                int weak_match;

                if (namelen < patlen ||
                    memcmp(name + namelen - patlen, pattern, patlen))
                        continue;
                if (namelen != patlen && name[namelen - patlen - 1] != '/')
                        continue;

                /* A match is "weak" if it is with refs outside
                 * heads or tags, and did not specify the pattern
                 * in full (e.g. "refs/remotes/origin/master") or at
                 * least from the toplevel (e.g. "remotes/origin/master");
                 * otherwise "git push $URL master" would result in
                 * ambiguity between remotes/origin/master and heads/master
                 * at the remote site.
                 */
                if (namelen != patlen &&
                    patlen != namelen - 5 &&
                    prefixcmp(name, "refs/heads/") &&
                    prefixcmp(name, "refs/tags/")) {
                        /* We want to catch the case where only weak
                         * matches are found and there are multiple
                         * matches, and where more than one strong
                         * matches are found, as ambiguous.  One
                         * strong match with zero or more weak matches
                         * are acceptable as a unique match.
                         */
                        matched_weak = refs;
                        weak_match++;
                }
                else {
                        matched = refs;
                        match++;
                }
        }
        if (!matched) {
                *matched_ref = matched_weak;
                return weak_match;
        }
        else {
                *matched_ref = matched;
                return match;
        }
}

static void link_dst_tail(struct ref *ref, struct ref ***tail)
{
        **tail = ref;
        *tail = &ref->next;
        **tail = NULL;
}

static struct ref *try_explicit_object_name(const char *name)
{
        unsigned char sha1[20];
        struct ref *ref;
        int len;

        if (!*name) {
                ref = xcalloc(1, sizeof(*ref) + 20);
                strcpy(ref->name, "(delete)");
                hashclr(ref->new_sha1);
                return ref;
        }
        if (get_sha1(name, sha1))
                return NULL;
        len = strlen(name) + 1;
        ref = xcalloc(1, sizeof(*ref) + len);
        memcpy(ref->name, name, len);
        hashcpy(ref->new_sha1, sha1);
        return ref;
}

static int match_explicit_refs(struct ref *src, struct ref *dst,
                               struct ref ***dst_tail, struct refspec *rs)
{
        int i, errs;
        for (i = errs = 0; rs[i].src; i++) {
                struct ref *matched_src, *matched_dst;

                matched_src = matched_dst = NULL;
                switch (count_refspec_match(rs[i].src, src, &matched_src)) {
                case 1:
                        break;
                case 0:
                        /* The source could be in the get_sha1() format
                         * not a reference name.  :refs/other is a
                         * way to delete 'other' ref at the remote end.
                         */
                        matched_src = try_explicit_object_name(rs[i].src);
                        if (matched_src)
                                break;
                        errs = 1;
                        error("src refspec %s does not match any.",
                              rs[i].src);
                        break;
                default:
                        errs = 1;
                        error("src refspec %s matches more than one.",
                              rs[i].src);
                        break;
                }
                switch (count_refspec_match(rs[i].dst, dst, &matched_dst)) {
                case 1:
                        break;
                case 0:
                        if (!memcmp(rs[i].dst, "refs/", 5)) {
                                int len = strlen(rs[i].dst) + 1;
                                matched_dst = xcalloc(1, sizeof(*dst) + len);
                                memcpy(matched_dst->name, rs[i].dst, len);
                                link_dst_tail(matched_dst, dst_tail);
                        }
                        else if (!strcmp(rs[i].src, rs[i].dst) &&
                                 matched_src) {
                                /* pushing "master:master" when
                                 * remote does not have master yet.
                                 */
                                int len = strlen(matched_src->name) + 1;
                                matched_dst = xcalloc(1, sizeof(*dst) + len);
                                memcpy(matched_dst->name, matched_src->name,
                                       len);
                                link_dst_tail(matched_dst, dst_tail);
                        }
                        else {
                                errs = 1;
                                error("dst refspec %s does not match any "
                                      "existing ref on the remote and does "
                                      "not start with refs/.", rs[i].dst);
                        }
                        break;
                default:
                        errs = 1;
                        error("dst refspec %s matches more than one.",
                              rs[i].dst);
                        break;
                }
                if (errs)
                        continue;
                if (matched_dst->peer_ref) {
                        errs = 1;
                        error("dst ref %s receives from more than one src.",
                              matched_dst->name);
                }
                else {
                        matched_dst->peer_ref = matched_src;
                        matched_dst->force = rs[i].force;
                }
        }
        return -errs;
}

static struct ref *find_ref_by_name(struct ref *list, const char *name)
{
        for ( ; list; list = list->next)
                if (!strcmp(list->name, name))
                        return list;
        return NULL;
}

int match_refs(struct ref *src, struct ref *dst, struct ref ***dst_tail,
               int nr_refspec, char **refspec, int all)
{
        struct refspec *rs = parse_ref_spec(nr_refspec, refspec);

        if (nr_refspec)
                return match_explicit_refs(src, dst, dst_tail, rs);

        /* pick the remainder */
        for ( ; src; src = src->next) {
                struct ref *dst_peer;
                if (src->peer_ref)
                        continue;
                dst_peer = find_ref_by_name(dst, src->name);
                if ((dst_peer && dst_peer->peer_ref) || (!dst_peer && !all))
                        continue;
                if (!dst_peer) {
                        /* Create a new one and link it */
                        int len = strlen(src->name) + 1;
                        dst_peer = xcalloc(1, sizeof(*dst_peer) + len);
                        memcpy(dst_peer->name, src->name, len);
                        hashcpy(dst_peer->new_sha1, src->new_sha1);
                        link_dst_tail(dst_peer, dst_tail);
                }
                dst_peer->peer_ref = src;
        }
        return 0;
}

enum protocol {
        PROTO_LOCAL = 1,
        PROTO_SSH,
        PROTO_GIT,
};

static enum protocol get_protocol(const char *name)
{
        if (!strcmp(name, "ssh"))
                return PROTO_SSH;
        if (!strcmp(name, "git"))
                return PROTO_GIT;
        if (!strcmp(name, "git+ssh"))
                return PROTO_SSH;
        if (!strcmp(name, "ssh+git"))
                return PROTO_SSH;
        die("I don't handle protocol '%s'", name);
}

#define STR_(s) # s
#define STR(s)  STR_(s)

#ifndef NO_IPV6

/*
 * Returns a connected socket() fd, or else die()s.
 */
static int git_tcp_connect_sock(char *host)
{
        int sockfd = -1, saved_errno = 0;
        char *colon, *end;
        const char *port = STR(DEFAULT_GIT_PORT);
        struct addrinfo hints, *ai0, *ai;
        int gai;

        if (host[0] == '[') {
                end = strchr(host + 1, ']');
                if (end) {
                        *end = 0;
                        end++;
                        host++;
                } else
                        end = host;
        } else
                end = host;
        colon = strchr(end, ':');

        if (colon) {
                *colon = 0;
                port = colon + 1;
                if (!*port)
                        port = "<none>";
        }

        memset(&hints, 0, sizeof(hints));
        hints.ai_socktype = SOCK_STREAM;
        hints.ai_protocol = IPPROTO_TCP;

        gai = getaddrinfo(host, port, &hints, &ai);
        if (gai)
                die("Unable to look up %s (port %s) (%s)", host, port, gai_strerror(gai));

        for (ai0 = ai; ai; ai = ai->ai_next) {
                sockfd = socket(ai->ai_family,
                                ai->ai_socktype, ai->ai_protocol);
                if (sockfd < 0) {
                        saved_errno = errno;
                        continue;
                }
                if (connect(sockfd, ai->ai_addr, ai->ai_addrlen) < 0) {
                        saved_errno = errno;
                        close(sockfd);
                        sockfd = -1;
                        continue;
                }
                break;
        }

        freeaddrinfo(ai0);

        if (sockfd < 0)
                die("unable to connect a socket (%s)", strerror(saved_errno));

        return sockfd;
}

#else /* NO_IPV6 */

/*
 * Returns a connected socket() fd, or else die()s.
 */
static int git_tcp_connect_sock(char *host)
{
        int sockfd = -1, saved_errno = 0;
        char *colon, *end;
        char *port = STR(DEFAULT_GIT_PORT), *ep;
        struct hostent *he;
        struct sockaddr_in sa;
        char **ap;
        unsigned int nport;

        if (host[0] == '[') {
                end = strchr(host + 1, ']');
                if (end) {
                        *end = 0;
                        end++;
                        host++;
                } else
                        end = host;
        } else
                end = host;
        colon = strchr(end, ':');

        if (colon) {
                *colon = 0;
                port = colon + 1;
        }

        he = gethostbyname(host);
        if (!he)
                die("Unable to look up %s (%s)", host, hstrerror(h_errno));
        nport = strtoul(port, &ep, 10);
        if ( ep == port || *ep ) {
                /* Not numeric */
                struct servent *se = getservbyname(port,"tcp");
                if ( !se )
                        die("Unknown port %s\n", port);
                nport = se->s_port;
        }

        for (ap = he->h_addr_list; *ap; ap++) {
                sockfd = socket(he->h_addrtype, SOCK_STREAM, 0);
                if (sockfd < 0) {
                        saved_errno = errno;
                        continue;
                }

                memset(&sa, 0, sizeof sa);
                sa.sin_family = he->h_addrtype;
                sa.sin_port = htons(nport);
                memcpy(&sa.sin_addr, *ap, he->h_length);

                if (connect(sockfd, (struct sockaddr *)&sa, sizeof sa) < 0) {
                        saved_errno = errno;
                        close(sockfd);
                        sockfd = -1;
                        continue;
                }
                break;
        }

        if (sockfd < 0)
                die("unable to connect a socket (%s)", strerror(saved_errno));

        return sockfd;
}

#endif /* NO_IPV6 */


static void git_tcp_connect(int fd[2], char *host)
{
        int sockfd = git_tcp_connect_sock(host);

        fd[0] = sockfd;
        fd[1] = dup(sockfd);
}


static char *git_proxy_command;
static const char *rhost_name;
static int rhost_len;

static int git_proxy_command_options(const char *var, const char *value)
{
        if (!strcmp(var, "core.gitproxy")) {
                const char *for_pos;
                int matchlen = -1;
                int hostlen;

                if (git_proxy_command)
                        return 0;
                /* [core]
                 * ;# matches www.kernel.org as well
                 * gitproxy = netcatter-1 for kernel.org
                 * gitproxy = netcatter-2 for sample.xz
                 * gitproxy = netcatter-default
                 */
                for_pos = strstr(value, " for ");
                if (!for_pos)
                        /* matches everybody */
                        matchlen = strlen(value);
                else {
                        hostlen = strlen(for_pos + 5);
                        if (rhost_len < hostlen)
                                matchlen = -1;
                        else if (!strncmp(for_pos + 5,
                                          rhost_name + rhost_len - hostlen,
                                          hostlen) &&
                                 ((rhost_len == hostlen) ||
                                  rhost_name[rhost_len - hostlen -1] == '.'))
                                matchlen = for_pos - value;
                        else
                                matchlen = -1;
                }
                if (0 <= matchlen) {
                        /* core.gitproxy = none for kernel.org */
                        if (matchlen == 4 && 
                            !memcmp(value, "none", 4))
                                matchlen = 0;
                        git_proxy_command = xmalloc(matchlen + 1);
                        memcpy(git_proxy_command, value, matchlen);
                        git_proxy_command[matchlen] = 0;
                }
                return 0;
        }

        return git_default_config(var, value);
}

static int git_use_proxy(const char *host)
{
        rhost_name = host;
        rhost_len = strlen(host);
        git_proxy_command = getenv("GIT_PROXY_COMMAND");
        git_config(git_proxy_command_options);
        rhost_name = NULL;
        return (git_proxy_command && *git_proxy_command);
}

static void git_proxy_connect(int fd[2], char *host)
{
        const char *port = STR(DEFAULT_GIT_PORT);
        char *colon, *end;
        const char *argv[4];
        struct child_process proxy;

        if (host[0] == '[') {
                end = strchr(host + 1, ']');
                if (end) {
                        *end = 0;
                        end++;
                        host++;
                } else
                        end = host;
        } else
                end = host;
        colon = strchr(end, ':');

        if (colon) {
                *colon = 0;
                port = colon + 1;
        }

        argv[0] = git_proxy_command;
        argv[1] = host;
        argv[2] = port;
        argv[3] = NULL;
        memset(&proxy, 0, sizeof(proxy));
        proxy.argv = argv;
        proxy.in = -1;
        proxy.out = -1;
        if (start_command(&proxy))
                die("cannot start proxy %s", argv[0]);
        fd[0] = proxy.out; /* read from proxy stdout */
        fd[1] = proxy.in;  /* write to proxy stdin */
}

#define MAX_CMD_LEN 1024

/*
 * This returns 0 if the transport protocol does not need fork(2),
 * or a process id if it does.  Once done, finish the connection
 * with finish_connect() with the value returned from this function
 * (it is safe to call finish_connect() with 0 to support the former
 * case).
 *
 * Does not return a negative value on error; it just dies.
 */
pid_t git_connect(int fd[2], char *url, const char *prog)
{
        char *host, *path = url;
        char *end;
        int c;
        int pipefd[2][2];
        pid_t pid;
        enum protocol protocol = PROTO_LOCAL;
        int free_path = 0;

        /* Without this we cannot rely on waitpid() to tell
         * what happened to our children.
         */
        signal(SIGCHLD, SIG_DFL);

        host = strstr(url, "://");
        if(host) {
                *host = '\0';
                protocol = get_protocol(url);
                host += 3;
                c = '/';
        } else {
                host = url;
                c = ':';
        }

        if (host[0] == '[') {
                end = strchr(host + 1, ']');
                if (end) {
                        *end = 0;
                        end++;
                        host++;
                } else
                        end = host;
        } else
                end = host;

        path = strchr(end, c);
        if (c == ':') {
                if (path) {
                        protocol = PROTO_SSH;
                        *path++ = '\0';
                } else
                        path = host;
        }

        if (!path || !*path)
                die("No path specified. See 'man git-pull' for valid url syntax");

        /*
         * null-terminate hostname and point path to ~ for URL's like this:
         *    ssh://host.xz/~user/repo
         */
        if (protocol != PROTO_LOCAL && host != url) {
                char *ptr = path;
                if (path[1] == '~')
                        path++;
                else {
                        path = xstrdup(ptr);
                        free_path = 1;
                }

                *ptr = '\0';
        }

        if (protocol == PROTO_GIT) {
                /* These underlying connection commands die() if they
                 * cannot connect.
                 */
                char *target_host = xstrdup(host);
                if (git_use_proxy(host))
                        git_proxy_connect(fd, host);
                else
                        git_tcp_connect(fd, host);
                /*
                 * Separate original protocol components prog and path
                 * from extended components with a NUL byte.
                 */
                packet_write(fd[1],
                             "%s %s%chost=%s%c",
                             prog, path, 0,
                             target_host, 0);
                free(target_host);
                if (free_path)
                        free(path);
                return 0;
        }

        if (pipe(pipefd[0]) < 0 || pipe(pipefd[1]) < 0)
                die("unable to create pipe pair for communication");
        pid = fork();
        if (pid < 0)
                die("unable to fork");
        if (!pid) {
                char command[MAX_CMD_LEN];
                char *posn = command;
                int size = MAX_CMD_LEN;
                int of = 0;

                of |= add_to_string(&posn, &size, prog, 0);
                of |= add_to_string(&posn, &size, " ", 0);
                of |= add_to_string(&posn, &size, path, 1);

                if (of)
                        die("command line too long");

                dup2(pipefd[1][0], 0);
                dup2(pipefd[0][1], 1);
                close(pipefd[0][0]);
                close(pipefd[0][1]);
                close(pipefd[1][0]);
                close(pipefd[1][1]);
                if (protocol == PROTO_SSH) {
                        const char *ssh, *ssh_basename;
                        ssh = getenv("GIT_SSH");
                        if (!ssh) ssh = "ssh";
                        ssh_basename = strrchr(ssh, '/');
                        if (!ssh_basename)
                                ssh_basename = ssh;
                        else
                                ssh_basename++;
                        execlp(ssh, ssh_basename, host, command, NULL);
                }
                else {
                        unsetenv(ALTERNATE_DB_ENVIRONMENT);
                        unsetenv(DB_ENVIRONMENT);
                        unsetenv(GIT_DIR_ENVIRONMENT);
                        unsetenv(GRAFT_ENVIRONMENT);
                        unsetenv(INDEX_ENVIRONMENT);
                        execlp("sh", "sh", "-c", command, NULL);
                }
                die("exec failed");
        }
        fd[0] = pipefd[0][0];
        fd[1] = pipefd[1][1];
        close(pipefd[0][1]);
        close(pipefd[1][0]);
        if (free_path)
                free(path);
        return pid;
}

int finish_connect(pid_t pid)
{
        if (pid == 0)
                return 0;

        while (waitpid(pid, NULL, 0) < 0) {
                if (errno != EINTR)
                        return -1;
        }
        return 0;
}