/* $Id: buffer.c,v 1.7 2001-09-08 18:58:37 rjkaes Exp $ * * The buffer used in each connection is a linked list of lines. As the lines * are read in and written out the buffer expands and contracts. Basically, * by using this method we can increase the buffer size dynamicly. However, * we have a hard limit of 64 KB for the size of the buffer. The buffer can be * thought of as a queue were we act on both the head and tail. The various * functions act on each end (the names are taken from what Perl uses to act on * the ends of an array. :) * * Copyright (C) 1999 Robert James Kaes (rjkaes@flarenet.com) * * 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, 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. */ #include "tinyproxy.h" #include "buffer.h" #include "log.h" #include "utils.h" #define BUFFER_HEAD(x) (((struct buffer_s *)(x))->head) #define BUFFER_TAIL(x) (((struct buffer_s *)(x))->tail) struct bufline_s { unsigned char *string; /* the actual string of data */ struct bufline_s *next; /* pointer to next in linked list */ size_t length; /* length of the string of data */ size_t pos; /* start sending from this offset */ }; struct buffer_s { struct bufline_s *head; /* top of the buffer */ struct bufline_s *tail; /* bottom of the buffer */ size_t size; /* total size of the buffer */ }; /* * Return the size of the supplied buffer. */ size_t buffer_size(struct buffer_s *buffptr) { assert(buffptr != NULL); return buffptr->size; } /* * Take a string of data and a length and make a new line which can be added * to the buffer */ static struct bufline_s *makenewline(unsigned char *data, size_t length) { struct bufline_s *newline; assert(data != NULL); if (!(newline = safemalloc(sizeof(struct bufline_s)))) return NULL; newline->string = data; newline->next = NULL; newline->length = length; newline->pos = 0; return newline; } /* * Free the allocated buffer line */ static void free_line(struct bufline_s *line) { assert(line != NULL); if (!line) return; if (line->string) { safefree(line->string); } safefree(line); } /* * Create a new buffer */ struct buffer_s *new_buffer(void) { struct buffer_s *buffptr; if (!(buffptr = safemalloc(sizeof(struct buffer_s)))) return NULL; buffptr->head = buffptr->tail = NULL; buffptr->size = 0; return buffptr; } /* * Delete all the lines in the buffer and the buffer itself */ void delete_buffer(struct buffer_s *buffptr) { struct bufline_s *next; assert(buffptr != NULL); while (BUFFER_HEAD(buffptr)) { next = BUFFER_HEAD(buffptr)->next; free_line(BUFFER_HEAD(buffptr)); BUFFER_HEAD(buffptr) = next; } BUFFER_HEAD(buffptr) = NULL; BUFFER_TAIL(buffptr) = NULL; safefree(buffptr); } /* * Push a new line on to the end of the buffer */ static int add_to_buffer(struct buffer_s *buffptr, unsigned char *data, size_t length) { struct bufline_s *newline; assert(buffptr != NULL); assert(data != NULL); if (!(newline = makenewline(data, length))) return -1; if (!BUFFER_HEAD(buffptr) && !BUFFER_TAIL(buffptr)) BUFFER_HEAD(buffptr) = BUFFER_TAIL(buffptr) = newline; else BUFFER_TAIL(buffptr) = (BUFFER_TAIL(buffptr)->next = newline); buffptr->size += length; return 0; } /* * Shift a line off the top of the buffer (remove the line from the top of * the buffer) */ static struct bufline_s *remove_from_buffer(struct buffer_s *buffptr) { struct bufline_s *line; assert(buffptr != NULL); if (!BUFFER_HEAD(buffptr) && !BUFFER_TAIL(buffptr)) { line = BUFFER_HEAD(buffptr); BUFFER_HEAD(buffptr) = BUFFER_TAIL(buffptr) = NULL; buffptr->size = 0; return line; } line = BUFFER_HEAD(buffptr); BUFFER_HEAD(buffptr) = line->next; if (!BUFFER_HEAD(buffptr)) BUFFER_TAIL(buffptr) = NULL; buffptr->size -= line->length; return line; } /* * Reads the bytes from the socket, and adds them to the buffer. * Takes a connection and returns the number of bytes read. */ ssize_t readbuff(int fd, struct buffer_s *buffptr) { ssize_t bytesin; unsigned char inbuf[MAXBUFFSIZE]; unsigned char *buffer; assert(fd >= 0); assert(buffptr != NULL); if (buffer_size(buffptr) >= MAXBUFFSIZE) return 0; bytesin = read(fd, inbuf, MAXBUFFSIZE - buffer_size(buffptr)); if (bytesin > 0) { if (!(buffer = safemalloc(bytesin))) { log_message(LOG_ERR, "Could not allocate memory in 'readbuff'"); return 0; } memcpy(buffer, inbuf, bytesin); if (add_to_buffer(buffptr, buffer, bytesin) < 0) { return -1; } return bytesin; } else if (bytesin == 0) { /* connection was closed by client */ return -1; } else { switch (errno) { #ifdef EWOULDBLOCK case EWOULDBLOCK: #else # ifdef EAGAIN case EAGAIN: # endif #endif case EINTR: return 0; default: log_message(LOG_ERR, "recv error (%s) in 'readbuff'.", strerror(errno)); return -1; } } } /* * Write the bytes in the buffer to the socket. * Takes a connection and returns the number of bytes written. */ ssize_t writebuff(int fd, struct buffer_s *buffptr) { ssize_t bytessent; struct bufline_s *line; assert(fd >= 0); assert(buffptr != NULL); line = BUFFER_HEAD(buffptr); if (buffer_size(buffptr) <= 0) return 0; bytessent = write(fd, line->string + line->pos, line->length - line->pos); if (bytessent >= 0) { /* bytes sent, adjust buffer */ line->pos += bytessent; if (line->pos == line->length) free_line(remove_from_buffer(buffptr)); return bytessent; } else { switch (errno) { #ifdef EWOULDBLOCK case EWOULDBLOCK: #else # ifdef EAGAIN case EAGAIN: # endif #endif case EINTR: return 0; case ENOBUFS: case ENOMEM: log_message(LOG_ERR, "send error [NOBUFS/NOMEM] (%s) in 'writebuff'.", strerror(errno)); return 0; default: log_message(LOG_ERR, "send error (%s) in 'writebuff'.", strerror(errno)); return -1; } } }