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#include <u.h>
#include <libc.h>
#include <bin.h>
#include <httpd.h>

typedef struct Strings          Strings;

struct Strings
{
        char    *s1;
        char    *s2;
};

static  char*           abspath(HConnect *cc, char *origpath, char *curdir);
static  int             getc(HConnect*);
static  char*           getword(HConnect*);
static  Strings         parseuri(HConnect *c, char*);
static  Strings         stripsearch(char*);

/*
 * parse the next request line
 * returns:
 *      1 ok
 *      0 eof
 *      -1 error
 */
int
hparsereq(HConnect *c, int timeout)
{
        Strings ss;
        char *vs, *v, *search, *uri, *origuri, *extra;

        if(c->bin != nil){
                hfail(c, HInternal);
                return -1;
        }

        /*
         * serve requests until a magic request.
         * later requests have to come quickly.
         * only works for http/1.1 or later.
         */
        if(timeout)
                alarm(timeout);
        if(hgethead(c, 0) < 0)
                return -1;
        if(timeout)
                alarm(0);
        c->reqtime = time(nil);
        c->req.meth = getword(c);
        if(c->req.meth == nil){
                hfail(c, HSyntax);
                return -1;
        }
        uri = getword(c);
        if(uri == nil || strlen(uri) == 0){
                hfail(c, HSyntax);
                return -1;
        }
        v = getword(c);
        if(v == nil){
                if(strcmp(c->req.meth, "GET") != 0){
                        hfail(c, HUnimp, c->req.meth);
                        return -1;
                }
                c->req.vermaj = 0;
                c->req.vermin = 9;
        }else{
                vs = v;
                if(strncmp(vs, "HTTP/", 5) != 0){
                        hfail(c, HUnkVers, vs);
                        return -1;
                }
                vs += 5;
                c->req.vermaj = strtoul(vs, &vs, 10);
                if(*vs != '.' || c->req.vermaj != 1){
                        hfail(c, HUnkVers, vs);
                        return -1;
                }
                vs++;
                c->req.vermin = strtoul(vs, &vs, 10);
                if(*vs != '\0'){
                        hfail(c, HUnkVers, vs);
                        return -1;
                }

                extra = getword(c);
                if(extra != nil){
                        hfail(c, HSyntax);
                        return -1;
                }
        }

        /*
         * the fragment is not supposed to be sent
         * strip it 'cause some clients send it
         */
        origuri = uri;
        uri = strchr(origuri, '#');
        if(uri != nil)
                *uri = 0;

        /*
         * http/1.1 requires the server to accept absolute
         * or relative uri's.  convert to relative with an absolute path
         */
        if(http11(c)){
                ss = parseuri(c, origuri);
                uri = ss.s1;
                c->req.urihost = ss.s2;
                if(uri == nil){
                        hfail(c, HBadReq, uri);
                        return -1;
                }
                origuri = uri;
        }

        /*
         * munge uri for search, protection, and magic
         */
        ss = stripsearch(origuri);
        origuri = ss.s1;
        search = ss.s2;
        uri = hurlunesc(c, origuri);
        uri = abspath(c, uri, "/");
        if(uri == nil || uri[0] == '\0'){
                hfail(c, HNotFound, "no object specified");
                return -1;
        }

        c->req.uri = uri;
        c->req.search = search;
        if(search)
                c->req.searchpairs = hparsequery(c, hstrdup(c, search));

        return 1;
}

static Strings
parseuri(HConnect *c, char *uri)
{
        Strings ss;
        char *urihost, *p;

        urihost = nil;
        ss.s1 = ss.s2 = nil;
        if(uri[0] != '/')
                if(cistrncmp(uri, "http://", 7) == 0)
                        uri += 5;               /* skip http: */
                else if (cistrncmp(uri, "https://", 8) == 0)
                        uri += 6;               /* skip https: */
                else
                        return ss;

        /*
         * anything starting with // is a host name or number
         * hostnames consists of letters, digits, - and .
         * for now, just ignore any port given
         */
        if(uri[0] == '/' && uri[1] == '/'){
                urihost = uri + 2;
                p = strchr(urihost, '/');
                if(p == nil)
                        uri = hstrdup(c, "/");
                else{
                        uri = hstrdup(c, p);
                        *p = '\0';
                }
                p = strchr(urihost, ':');
                if(p != nil)
                        *p = '\0';
        }

        if(uri[0] != '/' || uri[1] == '/')
                return ss;

        ss.s1 = uri;
        ss.s2 = hlower(urihost);
        return ss;
}
static Strings
stripsearch(char *uri)
{
        Strings ss;
        char *search;

        search = strchr(uri, '?');
        if(search != nil)
                *search++ = 0;
        ss.s1 = uri;
        ss.s2 = search;
        return ss;
}

/*
 *  to circumscribe the accessible files we have to eliminate ..'s
 *  and resolve all names from the root.
 */
static char*
abspath(HConnect *cc, char *origpath, char *curdir)
{
        char *p, *sp, *path, *work, *rpath;
        int len, n, c;

        if(curdir == nil)
                curdir = "/";
        if(origpath == nil)
                origpath = "";
        work = hstrdup(cc, origpath);
        path = work;

        /*
         * remove any really special characters
         */
        for(sp = "`;|"; *sp; sp++){
                p = strchr(path, *sp);
                if(p)
                        *p = 0;
        }

        len = strlen(curdir) + strlen(path) + 2 + UTFmax;
        if(len < 10)
                len = 10;
        rpath = halloc(cc, len);
        if(*path == '/')
                rpath[0] = 0;
        else
                strcpy(rpath, curdir);
        n = strlen(rpath);

        while(path){
                p = strchr(path, '/');
                if(p)
                        *p++ = 0;
                if(strcmp(path, "..") == 0){
                        while(n > 1){
                                n--;
                                c = rpath[n];
                                rpath[n] = 0;
                                if(c == '/')
                                        break;
                        }
                }else if(strcmp(path, ".") == 0){
                        ;
                }else if(n == 1)
                        n += snprint(rpath+n, len-n, "%s", path);
                else
                        n += snprint(rpath+n, len-n, "/%s", path);
                path = p;
        }

        if(strncmp(rpath, "/bin/", 5) == 0)
                strcpy(rpath, "/");
        return rpath;
}

static char*
getword(HConnect *c)
{
        char *buf;
        int ch, n;

        while((ch = getc(c)) == ' ' || ch == '\t' || ch == '\r')
                ;
        if(ch == '\n')
                return nil;
        n = 0;
        buf = halloc(c, 1);
        for(;;){
                switch(ch){
                case ' ':
                case '\t':
                case '\r':
                case '\n':
                        buf[n] = '\0';
                        return hstrdup(c, buf);
                }

                if(n < HMaxWord-1){
                        buf = bingrow(&c->bin, buf, n, n + 1, 0);
                        if(buf == nil)
                                return nil;
                        buf[n++] = ch;
                }
                ch = getc(c);
        }
}

static int
getc(HConnect *c)
{
        if(c->hpos < c->hstop)
                return *c->hpos++;
        return '\n';
}