buffer.c

/*
 *  Boa, an http server
 *  Copyright (C) 1995 Paul Phillips <paulp@go2net.com>
 *  Some changes Copyright (C) 1999 Jon Nelson <jnelson@boa.org>

 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 1, or (at your option)
 *  any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */

/* $Id: buffer.c,v 1.10.2.2 2002/07/26 03:03:44 jnelson Exp $ */

#include "boa.h"
#include "escape.h"

#define INT_TO_HEX(x) \
    ((((x)-10)>=0)?('A'+((x)-10)):('0'+(x)))

/*
 * Name: req_write
 *
 * Description: Buffers data before sending to client.
 * Returns: -1 for error, otherwise how much is stored
 */

int req_write(request * req, char *msg)
{
    int msg_len;

    msg_len = strlen(msg);

    if (!msg_len || req->status == DEAD)
        return req->buffer_end;

    if (req->buffer_end + msg_len > BUFFER_SIZE) {
        log_error_time();
        fprintf(stderr, "Ran out of Buffer space!\n");
        req->status = DEAD;
        return -1;
    }
    memcpy(req->buffer + req->buffer_end, msg, msg_len);
    req->buffer_end += msg_len;
    return req->buffer_end;
}

void reset_output_buffer(request *req)
{
    req->buffer_end = 0;
}

/*
 * Name: req_write_escape_http
 * Description: Buffers and "escapes" data before sending to client.
 *  as above, but translates as it copies, into a form suitably
 *  encoded for URLs in HTTP headers.
 * Returns: -1 for error, otherwise how much is stored
 */
int req_write_escape_http(request * req, char *msg)
{
    char c, *inp, *dest;
    int left;
    inp = msg;
    dest = req->buffer + req->buffer_end;
    /* 3 is a guard band, since we don't check the destination pointer
     * in the middle of a transfer of up to 3 bytes */
    left = BUFFER_SIZE - req->buffer_end - 3;
    while ((c = *inp++) && left > 0) {
        if (needs_escape((unsigned int) c)) {
            *dest++ = '%';
            *dest++ = INT_TO_HEX(c >> 4);
            *dest++ = INT_TO_HEX(c & 15);
            left -= 3;
        } else {
            *dest++ = c;
            left--;
        }
    }
    req->buffer_end = dest - req->buffer;
    if (left == 0) {
        log_error_time();
        fprintf(stderr, "Ran out of Buffer space!\n");
        req->status = DEAD;
        return -1;
    }
    return req->buffer_end;
}

/*
 * Name: req_write_escape_html
 * Description: Buffers and "escapes" data before sending to client.
 *  as above, but translates as it copies, into a form suitably
 *  encoded for HTML bodies.
 * Returns: -1 for error, otherwise how much is stored
 */
int req_write_escape_html(request * req, char *msg)
{
    char c, *inp, *dest;
    int left;
    inp = msg;
    dest = req->buffer + req->buffer_end;
    /* 5 is a guard band, since we don't check the destination pointer
     * in the middle of a transfer of up to 5 bytes */
    left = BUFFER_SIZE - req->buffer_end - 5;
    while ((c = *inp++) && left > 0) {
        switch (c) {
        case '>':
            *dest++ = '&';
            *dest++ = 'g';
            *dest++ = 't';
            *dest++ = ';';
            left -= 4;
            break;
        case '<':
            *dest++ = '&';
            *dest++ = 'l';
            *dest++ = 't';
            *dest++ = ';';
            left -= 4;
            break;
        case '&':
            *dest++ = '&';
            *dest++ = 'a';
            *dest++ = 'm';
            *dest++ = 'p';
            *dest++ = ';';
            left -= 5;
            break;
        case '\"':
            *dest++ = '&';
            *dest++ = 'q';
            *dest++ = 'u';
            *dest++ = 'o';
            *dest++ = 't';
            *dest++ = ';';
            left -= 6;
            break;
        default:
            *dest++ = c;
            left--;
        }
    }
    req->buffer_end = dest - req->buffer;
    if (left == 0) {
        log_error_time();
        fprintf(stderr, "Ran out of Buffer space!\n");
        req->status = DEAD;
        return -1;
    }
    return req->buffer_end;
}


/*
 * Name: flush_req
 *
 * Description: Sends any backlogged buffer to client.
 *
 * Returns: -2 for error, -1 for blocked, otherwise how much is stored
 */

int req_flush(request * req)
{
    int bytes_to_write;

    bytes_to_write = req->buffer_end - req->buffer_start;
    if (req->status == DEAD)
        return -2;

    if (bytes_to_write) {
        int bytes_written;

        bytes_written = write(req->fd, req->buffer + req->buffer_start,
                              bytes_to_write);

        if (bytes_written < 0) {
            if (errno == EWOULDBLOCK || errno == EAGAIN)
                return -1;      /* request blocked at the pipe level, but keep going */
            else {
                req->buffer_start = req->buffer_end = 0;
                if (errno != EPIPE)
                    perror("buffer flush"); /* OK to disable if your logs get too big */
                req->status = DEAD;
                req->buffer_end = 0;
                return -2;
            }
        }
#ifdef FASCIST_LOGGING
        log_error_time();
        fprintf(stderr, "%s:%d - Wrote \"", __FILE__, __LINE__);
        fwrite(req->buffer + req->buffer_start, sizeof (char),
               bytes_written, stderr);
        fprintf(stderr, "\" (%d bytes)\n", bytes_written);
#endif
        req->buffer_start += bytes_written;
    }
    if (req->buffer_start == req->buffer_end)
        req->buffer_start = req->buffer_end = 0;
    return req->buffer_end;     /* successful */
}

/*
 * Name: escape_string
 *
 * Description: escapes the string inp.  Uses variable buf.  If buf is
 *  NULL when the program starts, it will attempt to dynamically allocate
 *  the space that it needs, otherwise it will assume that the user
 *  has already allocated enough space for the variable buf, which
 *  could be up to 3 times the size of inp.  If the routine dynamically
 *  allocates the space, the user is responsible for freeing it afterwords
 * Returns: NULL on error, pointer to string otherwise.
 * Note: this function doesn't really belong here, I plopped it here to
 *  work around a "bug" in escape.h (it defines a global, so can't be
 *  used in multiple source files).  Actually, this routine shouldn't 
 *  exist anywhere, it's only usage is in get.c's handling of on-the-fly
 *  directory generation, which would be better configured to use a combination
 *  of req_write_escape_http and req_write_escape_html.  That would involve
 *  more work than I'm willing to put in right now, though, so here we are.
 */

char *escape_string(char *inp, char *buf)
{
    int max;
    char *index;
    unsigned char c;

    max = strlen(inp) * 3;

    if (buf == NULL && max)
        buf = malloc(sizeof (char) * max + 1);

    if (buf == NULL) {
        log_error_time();
        perror("malloc");
        return NULL;
    }

    index = buf;
    while ((c = *inp++) && max > 0) {
        if (needs_escape((unsigned int) c)) {
            *index++ = '%';
            *index++ = INT_TO_HEX(c >> 4);
            *index++ = INT_TO_HEX(c & 15);
        } else
            *index++ = c;
    }
    *index = '\0';
    return buf;
}