dav/main.c

/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright 2013 Olaf Wintermann. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   1. Redistributions of source code must retain the above copyright
 *      notice, this list of conditions and the following disclaimer.
 *
 *   2. Redistributions in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <time.h>
#include <libxml/xmlerror.h>
#include <sys/types.h>
#include <ucx/string.h>
#include <dirent.h>


#include <libidav/utils.h>
#include <libidav/crypto.h>
#include "config.h"
#include "main.h"

static DavContext *ctx;

void xmlerrorfnc(void * c, const char * msg, ... ) {
    // nothing
}

#include <libidav/session.h>
void test() {
    
}

int main(int argc, char **argv) {
    xmlGenericErrorFunc fnc = xmlerrorfnc;
    initGenericErrorDefaultFunc(&fnc);
    ctx = dav_context_new();
    load_config(ctx);
    //dav_add_namespace(ctx, "U", "http://www.uap-core.de/");
    
    //test();
    
    memcpy(ctx->http_proxy, get_http_proxy(), sizeof(Proxy));
    memcpy(ctx->https_proxy, get_https_proxy(), sizeof(Proxy));
    
    if(argc < 2) {
        fprintf(stderr, "Missing command\n");
        print_usage(argv[0]);
        return -1;
    }
    
    char *cmd = argv[1];
    CmdArgs *args = cmd_parse_args(argc - 2, argv + 2);
    if(!args) {
        print_usage(argv[0]);
        return -1;
    }
    
    int ret = -1;
    if(!strcasecmp(cmd, "list") || !strcasecmp(cmd, "ls")) {
        ret = cmd_list(args);
    } else if(!strcasecmp(cmd, "get")) {
        ret = cmd_get(args);
    } else if(!strcasecmp(cmd, "put")) {
        ret = cmd_put(args);
    } else if(
            !strcasecmp(cmd, "remove") ||
            !strcasecmp(cmd, "rm") ||
            !strcasecmp(cmd, "delete"))
    {
        ret = cmd_remove(args);
    } else if(!strcasecmp(cmd, "mkdir") || !strcasecmp(cmd, "mkcol")) {
        ret = cmd_mkdir(args);
    } else if(!strcasecmp(cmd, "date")) {
        ret = cmd_date(args);
    } else {
        print_usage(argv[0]);
    }
    dav_context_destroy(ctx);
    
    return ret;
}

void print_usage(char *cmd) {
    fprintf(stderr, "Usage: %s command [options] arguments...\n\n", cmd);
    fprintf(stderr, "Commands:\n");
    fprintf(stderr, "        list [-altpcR] [-u <date>] <url>\n");
    fprintf(
            stderr,
            "        get [-pcR] [-o <file>] [-u <date>] <url>\n");
    fprintf(stderr, "        put [-pcR] [-k <key>] <url> <file>\n");
    fprintf(stderr, "        mkdir [-pc] [-k <key>] <url>\n");
    fprintf(stderr, "        remove [-pc] <url>\n");
    fprintf(stderr, "        date [url]\n");
    fprintf(stderr, "\n");
    fprintf(stderr, "Options:\n");
    fprintf(stderr,
            "        -k <key>   Key to use for encryption or decryption\n");
    fprintf(stderr, "        -p         Don't encrypt or decrypt files\n");
    fprintf(stderr, "        -c         Enable full encryption\n");
    fprintf(stderr,
            "        -R         "
            "Recursively do the operation for all children\n");
    fprintf(stderr, "        -o <file>  Write output to file\n");
    fprintf(
            stderr,
            "        -u <date>  "
            "Get resources which are modified since the specified date\n");
    fprintf(stderr, "        -a         show all files\n");
    fprintf(stderr, "        -l         print resources in long list format\n");
    fprintf(stderr, "        -t         print content type\n");
    fprintf(stderr, "\n");
    fprintf(stderr,
            "Instead of an url you can pass a repository name "
            "with an optional path:\n");
    fprintf(stderr, "        <repository>/path/\n");
    fprintf(stderr, "\n");
}

int request_auth(Repository *repo, DavSession *sn) {
    static int login = 0;
    if(login) {
        return 0;
    }
    
    char *user = NULL;
    char *password = NULL;
    char ubuf[256];
    char pbuf[256];
    if(repo->user) {
       user = repo->user; 
    } else {
        printf("user: ");
        fflush(stdout);
        user = fgets(ubuf, 256, stdin);
    }
    
    printf("password: ");
    fflush(stdout);
    password = fgets(pbuf, 256, stdin);
    
    size_t ulen = strlen(user);
    if(user[ulen-1] == '\n') {
        user[ulen-1] = '\0';
    }
    size_t plen = strlen(password);
    if(password[plen-1] == '\n') {
        password[plen-1] = '\0';
    }
    
    dav_session_set_auth(sn, user, password);
    login = 1;
    return 1;
}

Repository* url2repo(char *url, char **path) {
    size_t ulen = strlen(url);
    *path = NULL;
    
    int s;
    if(ulen > 7 && !strncasecmp(url, "http://", 7)) {
        s = 7;
    } else if(ulen > 8 && !strncasecmp(url, "https://", 8)) {
        s = 8;
    } else {
        s = 1;
    }
    
    sstr_t r = sstr(url);
    sstr_t p = sstr("/");
    for(int i=s;i<ulen;i++) {
        char c = url[i];
        if(c == '/') {
            r = sstrn(url, i);
            p = sstrsubs(sstr(url), i);
            if(p.length == 0) {
                p = sstrn("/", 1);
            }
            break;
        }
    }
    
    Repository *repo = get_repository(r);
    if(repo) {
        *path = sstrdup(p).ptr;
    } else {
        repo = calloc(1, sizeof(Repository));
        repo->name = "";
        repo->url = strdup(url);
        repo->decrypt_content = true;
        *path = strdup("/");
    }
    
    return repo;
}

void print_resource_error(DavSession *sn, char *path) {
    char *res_url = util_concat_path(sn->base_url, path);
    switch(sn->error) {
        default: {
            fprintf(stderr, "Operation failed for resource %s.\n", res_url);
            break;
        }
        case DAV_NOT_FOUND: {
            fprintf(stderr, "Resource %s not found.\n", res_url);
            break;
        }
        case DAV_UNAUTHORIZED: {
            fprintf(stderr, "Authentication required.\n");
            break;
        }
        case DAV_FORBIDDEN: {
            fprintf(stderr, "Access forbidden.\n");
            break;
        }
        case DAV_METHOD_NOT_ALLOWED: {
            fprintf(stderr, "Method not allowed.\n");
        }
        case DAV_CONFLICT: {
            fprintf(
                    stderr,
                    "Missing intermediate collections for resource %s.\n",
                    res_url);
        }
    }
    free(res_url);
}

int set_session_config(DavSession *sn, CmdArgs *a) {
    char *plain = cmd_getoption(a, "plain");
    char *crypt = cmd_getoption(a, "crypt");
    
    if(plain && crypt) {
        fprintf(stderr, "Error: -p and -c option set\n");
        return 1;
    }
    
    if(plain) {
        int flags = sn->flags;
        dav_session_set_flags(sn, 0);
    } else if(crypt) {
        dav_session_set_flags(sn, DAV_SESSION_FULL_ENCRYPTION);
    }
    
    return 0;
}


int cmd_list(CmdArgs *a) {
    if(a->argc != 1) {
        fprintf(stderr, "Too %s arguments\n", a->argc < 1 ? "few":"many");
        return -1;
    }
    
    char *url = a->argv[0];
    char *path = NULL;
    //char *base = NULL;
    Repository *repo = url2repo(url, &path);
    //base = util_concat_path(repo->url, path);
    DavSession *sn = dav_session_new_auth(ctx, repo->url, repo->user, repo->password);
    dav_session_set_flags(sn, get_repository_flags(repo));
    sn->key = dav_context_get_key(ctx, repo->default_key);
    
    if(set_session_config(sn, a)) {
        return -1;
    }
    
    char *update = cmd_getoption(a, "update");
    time_t t = 0;
    if(update) {
        t = util_parse_lastmodified(update);
    }
    
    int depth = cmd_getoption(a, "recursive") ? -1 : 1;
    int ret = -1;
    DavResource *ls;
    while(ret != 0) {
        ls = dav_query(
                sn,
                "get idav:crypto-name,idav:crypto-key from %s where lastmodified > %t with depth %d",
                path,
                t,
                depth);
        
        if(!ls) {
            if(sn->error == DAV_UNAUTHORIZED) {
                if(request_auth(repo, sn)) {
                    continue;
                }
            }
            print_resource_error(sn, path);
            break;
        }
        
        // parameters
        int show_all = cmd_getoption(a, "all") ? 1 : 0;
        void (*print_func)(DavResource*, CmdArgs *);
        if(cmd_getoption(a, "list")) {
            print_func = ls_print_list_elm;
        } else {
            print_func = ls_print_elm;
        }
        DavResource *child = ls->children;
        while(child) {
            if(child->name[0] != '.' || show_all) {
                print_func(child, a);
            }
            child = child->next;
        }
        
        // leave loop
        ret = 0;
    }
    
    free(path);
    //free(base);
    
    return ret;
}

static char* ls_date_str(time_t tm) {
    struct tm t;
    struct tm n;
    time_t now = time(NULL);
#ifdef _WIN32
    memcpy(&t, localtime(&tm), sizeof(struct tm));
    memcpy(&n, localtime(&now), sizeof(struct tm));
#else
    localtime_r(&tm, &t);
    localtime_r(&now, &n);
#endif /* _WIN32 */
    char *str = malloc(16);
    if(t.tm_year == n.tm_year) {
        strftime(str, 16, "%b %d %H:%M", &t);
    } else {
        strftime(str, 16, "%b %d  %Y", &t);
    }
    return str;
}

static char* ls_size_str(DavResource *res) {
    char *str = malloc(16);
    uint64_t size = res->contentlength;
    
    if(res->iscollection) {
        snprintf(str, 16, "");
    } else if(size < 0x400) {
        snprintf(str, 16, "%" PRIu64 " bytes", size);
    } else if(size < 0x100000) {
        float s = (float)size/0x400;
        int diff = (s*100 - (int)s*100);
        if(diff > 90) {
            diff = 0;
            s += 0.10f;
        }
        if(size < 0x2800 && diff != 0) {
            // size < 10 KiB
            snprintf(str, 16, "%.1f KiB", s);
        } else {
            snprintf(str, 16, "%.0f KiB", s);
        }
    } else if(size < 0x40000000) {
        float s = (float)size/0x100000;
        int diff = (s*100 - (int)s*100);
        if(diff > 90) {
            diff = 0;
            s += 0.10f;
        }
        if(size < 0xa00000 && diff != 0) {
            // size < 10 MiB
            snprintf(str, 16, "%.1f MiB", s);
        } else {
            size /= 0x100000;
            snprintf(str, 16, "%.0f MiB", s);
        }
    } else if(size < 0x1000000000ULL) {
        float s = (float)size/0x40000000;
        int diff = (s*100 - (int)s*100);
        if(diff > 90) {
            diff = 0;
            s += 0.10f;
        }
        if(size < 0x280000000 && diff != 0) {
            // size < 10 GiB
            snprintf(str, 16, "%.1f GiB", s);
        } else {
            size /= 0x40000000;
            snprintf(str, 16, "%.0f GiB", s);
        }
    } else {
        size /= 1024;
        float s = (float)size/0x40000000;
        int diff = (s*100 - (int)s*100);
        if(diff > 90) {
            diff = 0;
            s += 0.10f;
        }
        if(size < 0x280000000 && diff != 0) {
            // size < 10 TiB
            snprintf(str, 16, "%.1f TiB", s);
        } else {
            size /= 0x40000000;
            snprintf(str, 16, "%.0f TiB", s);
        }
    }
    return str;
}

void ls_print_list_elm(DavResource *res, CmdArgs *a) {
    int recursive = cmd_getoption(a, "recursive") ? 1 : 0;
    
    char flags[16];
    memset(flags, '-', 15);
    flags[2] = '\0';
    
    int type_width = 0;
    char *type = res->contenttype;
    
    if(res->iscollection) {
        flags[0] = 'd';
        type = "";
    }
    char *keyprop = dav_get_property_ns(
            res,
            DAV_NS,
            "crypto-key");
    if(keyprop) {
        flags[1] = 'c';
    }
    
    if(cmd_getoption(a, "type")) {
        type_width = 20;
    }
    if(type == NULL || type_width == 0) {
        type = "";
    }
    
    char *date = ls_date_str(res->lastmodified);
    char *size = ls_size_str(res);
    char *name = recursive ? res->path+1 : res->name;
    printf(
            "%s %*s %10s  %12s  %s\n",
            flags,
            type_width, type,
            size,
            date,
            name);
    free(date);
    free(size);
    
    if(recursive) {
        DavResource *child = res->children;
        while(child) {
            ls_print_list_elm(child, a);
            child = child->next;
        }
    }
}

void ls_print_elm(DavResource *res, CmdArgs *a) {
    int recursive = cmd_getoption(a, "recursive") ? 1 : 0;
    char *name = recursive ? res->path+1 : res->name;
    printf("%s\n", name);
    if(recursive) {
        DavResource *child = res->children;
        while(child) {
            ls_print_elm(child, a);
            child = child->next;
        }
    }
}

int cmd_get(CmdArgs *a) {
    if(a->argc != 1) {
        // TODO: change this, when get supports retrieval of multiple files
        fprintf(stderr, "Too %s arguments\n", a->argc < 1 ? "few":"many");
        return -1;
    }
    
    char *url = a->argv[0];
    char *path = NULL;
    Repository *repo = url2repo(url, &path);
    DavSession *sn = dav_session_new_auth(ctx, repo->url, repo->user, repo->password);
    dav_session_set_flags(sn, get_repository_flags(repo));
    sn->key = dav_context_get_key(ctx, repo->default_key);
    
    if(set_session_config(sn, a)) {
        return -1;
    }
    
    char *update = cmd_getoption(a, "update");
    time_t t = 0;
    if(update) {
        t = util_parse_lastmodified(update);
    }
    
    int recursive = cmd_getoption(a, "recursive") ? 1 : 0;
    DavResource *res;
    
    int depth = recursive ? -1 : 1;
    res = dav_query(
            sn,
            "get - from %s where lastmodified > %t with depth %d",
            path,
            t,
            depth);
    
    if(!res) {
        print_resource_error(sn, path);
        return -1;
    }
    if(!recursive && res->iscollection) {
        char *res_url = util_concat_path(sn->base_url, path);
        fprintf(stderr, "Resource %s is a collection.\n", res_url);
        fprintf(stderr, "Use the -R option to download collections.\n");
        free(res_url);
        return -1;
    }
    
    /*
     * determine the output file
     * use stdout if the output file is -
     */
    char *outfile = cmd_getoption(a, "output");
    if(!outfile) {
        if(res->iscollection) {
            outfile = "";
        } else {
            outfile = res->name;
        }
    } else if(res->iscollection && !strcmp(outfile, "-")) {
        fprintf(
                stderr,
                "Cannot write output to stdout "
                "if the requested resource is a collection.\n");
        return -1;
    }
    
    int ret = get_resource(repo, res, a, outfile);
    
    return ret;
}

int get_resource(Repository *repo, DavResource *res, CmdArgs *a, char *out) {
    size_t outlen = strlen(out);
    // print some status message in recursive mode
    if(cmd_getoption(a, "recursive")) {
        char *res_url = util_concat_path(res->session->base_url, res->path);
        printf("get: %s\n", res_url);
        free(res_url);
    }
    
    if(res->iscollection) {
        // create directory
        if(outlen != 0) {
            mode_t mode = S_IRWXU | S_IRGRP | S_IXGRP | S_IROTH | S_IXOTH;
            int ret = util_mkdir(out, mode);
            if(ret != 0 && errno != EEXIST) {
                return 1;
            }
        }
        
        DavResource *child = res->children;
        while(child) {
            char *newout = outlen > 0 ?
                    util_concat_path(out, child->name) : child->name;
            int ret = get_resource(repo, child, a, newout);
            if(outlen > 0) {
                free(newout);
            }
            if(ret) {
                return 1;
            }
            child = child->next;
        }
        
        return 0;
    }
     
    FILE *fout = !strcmp(out, "-") ? stdout : fopen(out, "w");
    if(!fout) {
        fprintf(stderr, "cannot open output file\n");
        return -1;
    }
    
    int ret = dav_get_content(res, fout, (dav_write_func)fwrite);
    fclose(fout);
    if(ret && strcmp(out, "-")) {
        unlink(out);
    }
    
    return 0;
}

int cmd_put(CmdArgs *a) {
    if(a->argc != 2) {
        // TODO: change, when put supports multiple files (however it should do)
        fprintf(stderr, "Too %s arguments\n", a->argc < 2 ? "few":"many");
        return -1;
    }
    
    char *url = a->argv[0];
    char *file = a->argv[1];
    char *path = NULL;
    Repository *repo = url2repo(url, &path);
    DavSession *sn = dav_session_new_auth(ctx, repo->url, repo->user, repo->password);
    dav_session_set_flags(sn, get_repository_flags(repo));
    sn->key = dav_context_get_key(ctx, repo->default_key);
    
    if(set_session_config(sn, a)) {
        return -1;
    }
    
    // override the session key if the -k option is specified
    char *keyname = cmd_getoption(a, "key");
    if(keyname) {
        DavKey *key = dav_context_get_key(ctx, keyname);
        if(key) {
            sn->key = key;
        } else {
            fprintf(stderr, "Key %s not found!\nAbort.\n", keyname);
            // TODO: free
            return -1;
        }
    }
    
    int ret;
    if(!strcmp(file, "-")) {
        FILE *in = stdin;
        ret = put_file(repo, a, sn, path, "stdin", in);
    } else {
        ret = put_entry(repo, a, sn, path, file); 
    }
    
    return ret;
}

int put_entry(Repository *repo, CmdArgs *a, DavSession *sn, char *path, char *file) {
    int recursive = cmd_getoption(a, "recursive") ? 1 : 0;
    if(recursive) {
        printf("put: %s\n", file);
    }
    struct stat s;
    if(stat(file, &s)) {
        perror("stat");
        fprintf(stderr, "cannot stat file %s\n", file);
        return -1;
    }
    
    int ret = 0;
    if(S_ISDIR(s.st_mode)) {
        if(!recursive) {
            return 1;
        }
        DIR *dir = opendir(file);
        if(!dir) {
            // error
        }
        struct dirent *entry;
        while((entry = readdir(dir)) != NULL) {
            if(!strcmp(entry->d_name, ".") || !strcmp(entry->d_name, "..")) {
                continue;
            }
            char *entry_file = util_concat_path(file, entry->d_name);
            char *entry_path = util_concat_path(path, entry->d_name);
            int r = put_entry(repo, a, sn, entry_path, entry_file);
            free(entry_path);
            free(entry_file);
            if(r) {
                ret = 1;
                break;
            }
        }
        closedir(dir);
    } else if(S_ISREG(s.st_mode)) {
        /*
         * use stdin if the input file is -
         */
        FILE *in = fopen(file, "r");
        if(!in) {
            fprintf(stderr, "cannot open input file\n");
            return -1;
        }
        char *filename = util_resource_name(file);
        //path = util_concat_path(path, filename);
        ret = put_file(repo, a, sn, path, filename, in);
        //free(path);
        fclose(in);
    }
    
    return ret;
}

int put_file(Repository *repo, CmdArgs *a, DavSession *sn, char *path, char *name, FILE *in) {
    DavResource *res = dav_query(sn, "get - from %s", path);
    if(!res) {
        if(sn->error == DAV_NOT_FOUND) {
            res = dav_resource_new(sn, path);
            if(dav_create(res)) {
                fprintf(stderr, "Cannot create resource.\n");
                return -1;
            }
        } else {
            if(sn->errorstr) {
                fprintf(stderr, "Error: %s\n", sn->errorstr);
            } else {
                fprintf(stderr, "Error\n");
            }
            return -1;
        }
    } else if(res->iscollection) {
        // TODO: free res
        char *newpath = util_concat_path(path, name);
        free(path);
        path = newpath;
        res = dav_resource_new(sn, path);
        int ret = put_file(repo, a, sn, res->path, NULL, in);
        // TODO: free res
        return ret;
    }
    
    dav_set_content(res, in, (dav_read_func)fread);
    
    if(dav_store(res)) {
        print_resource_error(sn, res->path);
        fprintf(stderr, "Cannot upload file.\n");
        if(sn->errorstr) {
            fprintf(stderr, "%s\n", sn->errorstr);
        }
        fclose(in);
        return -1;
    }
    return 0;
}


int cmd_remove(CmdArgs *a) {
    if(a->argc != 1) {
        // TODO: change, when removal of multiple files is supported
        fprintf(stderr, "Too %s arguments\n", a->argc < 1 ? "few":"many");
        return -1;
    }
    
    char *url = a->argv[0];
    char *path = NULL;
    Repository *repo = url2repo(url, &path);
    DavSession *sn = dav_session_new_auth(ctx, repo->url, repo->user, repo->password);
    dav_session_set_flags(sn, get_repository_flags(repo));
    sn->key = dav_context_get_key(ctx, repo->default_key);
    
    if(set_session_config(sn, a)) {
        return -1;
    }
    
    DavResource *res = dav_resource_new(sn, path);
    if(!res) {
        fprintf(stderr, "error\n");
        return -1;
    }
    
    if(dav_delete(res)) {
        print_resource_error(sn, res->path);
        fprintf(stderr, "Cannot delete resource.\n");
        return -1;
    }
    
    return 0;
}

int cmd_mkdir(CmdArgs *a) {
    if(a->argc != 1) {
        // TODO: change, when creation of multiple dirs is supported
        fprintf(stderr, "Too %s arguments\n", a->argc < 1 ? "few":"many");
        return -1;
    }
    
    char *url = a->argv[0];
    char *path = NULL;
    Repository *repo = url2repo(url, &path);
    DavSession *sn = dav_session_new_auth(ctx, repo->url, repo->user, repo->password);
    dav_session_set_flags(sn, get_repository_flags(repo));
    sn->key = dav_context_get_key(ctx, repo->default_key);
    
    if(set_session_config(sn, a)) {
        return -1;
    }
    
    // override the session key if the -k option is specified
    char *keyname = cmd_getoption(a, "key");
    if(keyname) {
        DavKey *key = dav_context_get_key(ctx, keyname);
        if(key) {
            sn->key = key;
        } else {
            fprintf(stderr, "Key %s not found!\nAbort.\n", keyname);
            // TODO: free
            return -1;
        }
    }
    
    DavResource *res = dav_resource_new(sn, path);
    if(!res) {
        fprintf(stderr, "error\n");
        return -1;
    }
    res->iscollection = 1;
    
    if(dav_create(res)) {
        print_resource_error(sn, res->path);
        fprintf(stderr, "Cannot create collection.\n");
        return -1;
    }
    
    return 0;
}


static size_t get_date_header_cb(void *header, int s, int n, void *data) {
    char **date_str = (char**)data;
    
    //printf("header: %.*s\n", s*n, header);
    sstr_t h = sstrn(header, s*n);
    if(sstrprefix(h, S("Date:"))) {
        sstr_t v = sstrsubs(h, 5);
        v = sstrdup(sstrtrim(v));
        *date_str = v.ptr;
    }
    return s*n;
}

int cmd_date(CmdArgs *a) {
    if(a->argc < 1) {
        time_t now = time(NULL);
        struct tm *date = gmtime(&now);
        char str[32];
        putenv("LC_TIME=C");
        size_t len = strftime(str, 32, "%a, %d %b %Y %H:%M:%S GMT\n", date);
        fwrite(str, 1, len, stdout);
    } else if (a->argc == 1) {
        char *url = a->argv[0];
        char *path = NULL;
        Repository *repo = url2repo(url, &path);
        DavSession *sn = dav_session_new_auth(ctx, repo->url, repo->user, repo->password);
        dav_session_set_flags(sn, get_repository_flags(repo));
        sn->key = dav_context_get_key(ctx, repo->default_key);

        DavResource *res = dav_resource_new(sn, path);
        char *date = NULL;
        curl_easy_setopt(sn->handle, CURLOPT_HEADERFUNCTION, get_date_header_cb);
        curl_easy_setopt(sn->handle, CURLOPT_WRITEHEADER, &date);
        if(dav_exists(res) && date) {
            printf("%s\n", date);
        } else {
            return -1;
        }
        return 0;
    } else {
        fprintf(stderr, "Too many arguments\n");
        return -1;
    }
    return 0;
}

int cmd_sync(CmdArgs *a) {
    if(a->argc < 2) {
        fprintf(stderr, "Too few arguments\n");
        return -1;
    }
    
    return 0;
}