tinyproxy/src/network.c

/* tinyproxy - A fast light-weight HTTP proxy
 * Copyright (C) 2002, 2004 Robert James Kaes <rjkaes@users.sourceforge.net>
 *
 * 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 2 of the License, 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.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

/* The functions found here are used for communicating across a
 * network.  They include both safe reading and writing (which are
 * the basic building blocks) along with two functions for
 * easily reading a line of text from the network, and a function
 * to write an arbitrary amount of data to the network.
 */

#include "main.h"

#include "heap.h"
#include "network.h"

/*
 * Write the buffer to the socket. If an EINTR occurs, pick up and try
 * again. Keep sending until the buffer has been sent.
 */
ssize_t safe_write (int fd, const char *buffer, size_t count)
{
        ssize_t len;
        size_t bytestosend;

        assert (fd >= 0);
        assert (buffer != NULL);
        assert (count > 0);

        bytestosend = count;

        while (1) {
                len = send (fd, buffer, bytestosend, MSG_NOSIGNAL);

                if (len < 0) {
                        if (errno == EINTR)
                                continue;
                        else
                                return -errno;
                }

                if ((size_t) len == bytestosend)
                        break;

                buffer += len;
                bytestosend -= len;
        }

        return count;
}

/*
 * Matched pair for safe_write(). If an EINTR occurs, pick up and try
 * again.
 */
ssize_t safe_read (int fd, char *buffer, size_t count)
{
        ssize_t len;

        do {
                len = read (fd, buffer, count);
        } while (len < 0 && errno == EINTR);

        return len;
}

/*
 * Send a "message" to the file descriptor provided. This handles the
 * differences between the various implementations of vsnprintf. This code
 * was basically stolen from the snprintf() man page of Debian Linux
 * (although I did fix a memory leak. :)
 */
int write_message (int fd, const char *fmt, ...)
{
        ssize_t n;
        size_t size = (1024 * 8);       /* start with 8 KB and go from there */
        char *buf, *tmpbuf;
        va_list ap;

        if ((buf = (char *) safemalloc (size)) == NULL)
                return -1;

        while (1) {
                va_start (ap, fmt);
                n = vsnprintf (buf, size, fmt, ap);
                va_end (ap);

                /* If that worked, break out so we can send the buffer */
                if (n > -1 && (size_t) n < size)
                        break;

                /* Else, try again with more space */
                if (n > -1)
                        /* precisely what is needed (glibc2.1) */
                        size = n + 1;
                else
                        /* twice the old size (glibc2.0) */
                        size *= 2;

                if ((tmpbuf = (char *) saferealloc (buf, size)) == NULL) {
                        safefree (buf);
                        return -1;
                } else
                        buf = tmpbuf;
        }

        if (safe_write (fd, buf, n) < 0) {
                safefree (buf);
                return -1;
        }

        safefree (buf);
        return 0;
}

/*
 * Read in a "line" from the socket. It might take a few loops through
 * the read sequence. The full string is allocate off the heap and stored
 * at the whole_buffer pointer. The caller needs to free the memory when
 * it is no longer in use. The returned line is NULL terminated.
 *
 * Returns the length of the buffer on success (not including the NULL
 * termination), 0 if the socket was closed, and -1 on all other errors.
 */
#define SEGMENT_LEN (512)
#define MAXIMUM_BUFFER_LENGTH (128 * 1024)
ssize_t readline (int fd, char **whole_buffer)
{
        ssize_t whole_buffer_len;
        char buffer[SEGMENT_LEN];
        char *ptr;

        ssize_t ret;
        ssize_t diff;

        struct read_lines_s {
                char *data;
                size_t len;
                struct read_lines_s *next;
        };
        struct read_lines_s *first_line, *line_ptr;

        first_line =
            (struct read_lines_s *) safecalloc (sizeof (struct read_lines_s),
                                                1);
        if (!first_line)
                return -ENOMEM;

        line_ptr = first_line;

        whole_buffer_len = 0;
        for (;;) {
                ret = recv (fd, buffer, SEGMENT_LEN, MSG_PEEK);
                if (ret <= 0)
                        goto CLEANUP;

                ptr = (char *) memchr (buffer, '\n', ret);
                if (ptr)
                        diff = ptr - buffer + 1;
                else
                        diff = ret;

                whole_buffer_len += diff;

                /*
                 * Don't allow the buffer to grow without bound. If we
                 * get to more than MAXIMUM_BUFFER_LENGTH close.
                 */
                if (whole_buffer_len > MAXIMUM_BUFFER_LENGTH) {
                        ret = -ERANGE;
                        goto CLEANUP;
                }

                line_ptr->data = (char *) safemalloc (diff);
                if (!line_ptr->data) {
                        ret = -ENOMEM;
                        goto CLEANUP;
                }

                recv (fd, line_ptr->data, diff, 0);
                line_ptr->len = diff;

                if (ptr) {
                        line_ptr->next = NULL;
                        break;
                }

                line_ptr->next =
                    (struct read_lines_s *)
                    safecalloc (sizeof (struct read_lines_s), 1);
                if (!line_ptr->next) {
                        ret = -ENOMEM;
                        goto CLEANUP;
                }
                line_ptr = line_ptr->next;
        }

        *whole_buffer = (char *) safemalloc (whole_buffer_len + 1);
        if (!*whole_buffer) {
                ret = -ENOMEM;
                goto CLEANUP;
        }

        *(*whole_buffer + whole_buffer_len) = '\0';

        whole_buffer_len = 0;
        line_ptr = first_line;
        while (line_ptr) {
                memcpy (*whole_buffer + whole_buffer_len, line_ptr->data,
                        line_ptr->len);
                whole_buffer_len += line_ptr->len;

                line_ptr = line_ptr->next;
        }

        ret = whole_buffer_len;

CLEANUP:
        do {
                line_ptr = first_line->next;
                if (first_line->data)
                        safefree (first_line->data);
                safefree (first_line);
                first_line = line_ptr;
        } while (first_line);

        return ret;
}

/*
 * Convert the network address into either a dotted-decimal or an IPv6
 * hex string.
 */
char *get_ip_string (struct sockaddr *sa, char *buf, size_t buflen)
{
        assert (sa != NULL);
        assert (buf != NULL);
        assert (buflen != 0);
        buf[0] = '\0';          /* start with an empty string */

        switch (sa->sa_family) {
        case AF_INET:
                {
                        struct sockaddr_in *sa_in = (struct sockaddr_in *) sa;

                        inet_ntop (AF_INET, &sa_in->sin_addr, buf, buflen);
                        break;
                }
        case AF_INET6:
                {
                        struct sockaddr_in6 *sa_in6 =
                            (struct sockaddr_in6 *) sa;

                        inet_ntop (AF_INET6, &sa_in6->sin6_addr, buf, buflen);
                        break;
                }
        default:
                /* no valid family */
                return NULL;
        }

        return buf;
}

/*
 * Convert a numeric character string into an IPv6 network address
 * (in binary form.)  The function works just like inet_pton(), but it
 * will accept both IPv4 and IPv6 numeric addresses.
 *
 * Returns the same as inet_pton().
 */
int full_inet_pton (const char *ip, void *dst)
{
        char buf[24], tmp[24];  /* IPv4->IPv6 = ::FFFF:xxx.xxx.xxx.xxx\0 */
        int n;

        assert (ip != NULL && strlen (ip) != 0);
        assert (dst != NULL);

        /*
         * Check if the string is an IPv4 numeric address.  We use the
         * older inet_aton() call since it handles more IPv4 numeric
         * address formats.
         */
        n = inet_aton (ip, (struct in_addr *) dst);
        if (n == 0) {
                /*
                 * Simple case: "ip" wasn't an IPv4 numeric address, so
                 * try doing the conversion as an IPv6 address.  This
                 * will either succeed or fail, but we can't do any
                 * more processing anyway.
                 */
                return inet_pton (AF_INET6, ip, dst);
        }

        /*
         * "ip" was an IPv4 address, so we need to convert it to
         * an IPv4-mapped IPv6 address and do the conversion
         * again to get the IPv6 network structure.
         *
         * We convert the IPv4 binary address back into the
         * standard dotted-decimal format using inet_ntop()
         * so we can be sure that inet_pton will accept the
         * full string.
         */
        snprintf (buf, sizeof (buf), "::ffff:%s",
                  inet_ntop (AF_INET, dst, tmp, sizeof (tmp)));
        return inet_pton (AF_INET6, buf, dst);
}