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-rw-r--r--src/message.c554
1 files changed, 554 insertions, 0 deletions
diff --git a/src/message.c b/src/message.c
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index 0000000..c0372bd
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+++ b/src/message.c
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+/**
+ * gammad -- Cooperative gamma server
+ * Copyright (C) 2016 Mattias Andrée (maandree@kth.se)
+ *
+ * This library 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 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This library 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 library. If not, see <http://www.gnu.org/licenses/>.
+ */
+#include "message.h"
+#include "util.h"
+
+#include <sys/socket.h>
+#include <errno.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+
+
+
+/**
+ * Initialise a message slot so that it can
+ * be used by to read messages
+ *
+ * @param this Memory slot in which to store the new message
+ * @return Non-zero on error, `errno` will be set accordingly
+ */
+int message_initialise(struct message* this)
+{
+ this->headers = NULL;
+ this->header_count = 0;
+ this->payload = NULL;
+ this->payload_size = 0;
+ this->payload_ptr = 0;
+ this->buffer_size = 128;
+ this->buffer_ptr = 0;
+ this->stage = 0;
+ this->buffer = malloc(this->buffer_size);
+ if (this->buffer == NULL)
+ return -1;
+ return 0;
+}
+
+
+/**
+ * Release all resources in a message, should
+ * be done even if initialisation fails
+ *
+ * @param this The message
+ */
+void message_destroy(struct message* this)
+{
+ size_t i;
+ if (this->headers != NULL)
+ for (i = 0; i < this->header_count; i++)
+ free(this->headers[i]);
+
+ free(this->headers);
+ free(this->payload);
+ free(this->buffer);
+}
+
+
+/**
+ * Marshal a message for state serialisation
+ *
+ * @param this The message
+ * @param buf Output buffer for the marshalled data,
+ * `NULL` just measure how large the buffers
+ * needs to be
+ * @return The number of marshalled byte
+ */
+size_t message_marshal(const struct message* this, void* buf)
+{
+ size_t i, n, off = 0;
+ char* bs = buf;
+
+ if (bs != NULL)
+ *(size_t*)(bs + off) = this->header_count;
+ off += sizeof(size_t);
+
+ if (bs != NULL)
+ *(size_t*)(bs + off) = this->payload_size;
+ off += sizeof(size_t);
+
+ if (bs != NULL)
+ *(size_t*)(bs + off) = this->payload_ptr;
+ off += sizeof(size_t);
+
+ if (bs != NULL)
+ *(size_t*)(bs + off) = this->buffer_ptr;
+ off += sizeof(size_t);
+
+ if (bs != NULL)
+ *(int*)(bs + off) = this->stage;
+ off += sizeof(int);
+
+ for (i = 0; i < this->header_count; i++)
+ {
+ n = strlen(this->headers[i]) + 1;
+ if (bs != NULL)
+ memcpy(bs + off, this->headers[i], n);
+ off += n;
+ }
+
+ if (bs != NULL)
+ memcpy(bs + off, this->payload, this->payload_ptr);
+ off += this->payload_ptr;
+
+ if (bs != NULL)
+ memcpy(bs + off, this->buffer, this->buffer_ptr);
+ off += this->buffer_ptr;
+
+ return off;
+}
+
+
+/**
+ * Unmarshal a message for state deserialisation
+ *
+ * @param this Memory slot in which to store the new message
+ * @param buf In buffer with the marshalled data
+ * @return The number of unmarshalled bytes, 0 on error
+ */
+size_t message_unmarshal(struct message* this, const void* buf)
+{
+ size_t i, n, off = 0, header_count;
+ const char* bs = buf;
+
+ this->header_count = 0;
+
+ header_count = *(const size_t*)(bs + off);
+ off += sizeof(size_t);
+
+ this->payload_size = *(const size_t*)(bs + off);
+ off += sizeof(size_t);
+
+ this->payload_ptr = *(const size_t*)(bs + off);
+ off += sizeof(size_t);
+
+ this->buffer_size = this->buffer_ptr = *(const size_t*)(bs + off);
+ off += sizeof(size_t);
+
+ this->stage = *(const int*)(bs + off);
+ off += sizeof(int);
+
+ /* Make sure that the pointers are NULL so that they are
+ not freed without being allocated when the message is
+ destroyed if this function fails. */
+ this->headers = NULL;
+ this->payload = NULL;
+ this->buffer = NULL;
+
+ /* To 2-power-multiple of 128 bytes. */
+ this->buffer_size >>= 7;
+ if (this->buffer_size == 0)
+ this->buffer_size = 1;
+ else
+ {
+ this->buffer_size -= 1;
+ this->buffer_size |= this->buffer_size >> 1;
+ this->buffer_size |= this->buffer_size >> 2;
+ this->buffer_size |= this->buffer_size >> 4;
+ this->buffer_size |= this->buffer_size >> 8;
+ this->buffer_size |= this->buffer_size >> 16;
+#if SIZE_MAX == UINT64_MAX
+ this->buffer_size |= this->buffer_size >> 32;
+#endif
+ this->buffer_size += 1;
+ }
+ this->buffer_size <<= 7;
+
+ /* Allocate header list, payload and read buffer. */
+
+ if (header_count > 0)
+ if (!(this->headers = malloc(header_count * sizeof(char*))))
+ goto fail;
+
+ if (this->payload_size > 0)
+ if (!(this->payload = malloc(this->payload_size)))
+ goto fail;
+
+ if (!(this->buffer = malloc(this->buffer_size)))
+ goto fail;
+
+ /* Fill the header list, payload and read buffer. */
+
+ for (i = 0; i < header_count; i++)
+ {
+ n = strlen(bs + off) + 1;
+ this->headers[i] = memdup(bs + off, n);
+ if (this->headers[i] == NULL)
+ goto fail;
+ off += n;
+ this->header_count++;
+ }
+
+ memcpy(this->payload, bs + off, this->payload_ptr);
+ off += this->payload_ptr;
+
+ memcpy(this->buffer, bs + off, this->buffer_ptr);
+ off += this->buffer_ptr;
+
+ return off;
+
+ fail:
+ return 0;
+}
+
+
+/**
+ * Extend the header list's allocation
+ *
+ * @param this The message
+ * @param extent The number of additional entries
+ * @return Zero on success, -1 on error
+ */
+static int extend_headers(struct message* this, size_t extent)
+{
+ char** new;
+ if (!(new = realloc(this->headers, (this->header_count + extent) * sizeof(char*))))
+ return -1;
+ this->headers = new;
+ return 0;
+}
+
+
+/**
+ * Extend the read buffer by way of doubling
+ *
+ * @param this The message
+ * @return Zero on success, -1 on error
+ */
+static int extend_buffer(struct message* this)
+{
+ char* new;
+ if (!(new = realloc(this->buffer, (this->buffer_size << 1) * sizeof(char))))
+ return -1;
+ this->buffer = new;
+ this->buffer_size <<= 1;
+ return 0;
+}
+
+
+/**
+ * Reset the header list and the payload
+ *
+ * @param this The message
+ */
+static void reset_message(struct message* this)
+{
+ size_t i;
+ if (this->headers != NULL)
+ for (i = 0; i < this->header_count; i++)
+ free(this->headers[i]);
+ free(this->headers);
+ this->headers = NULL;
+ this->header_count = 0;
+
+ free(this->payload);
+ this->payload = NULL;
+ this->payload_size = 0;
+ this->payload_ptr = 0;
+}
+
+
+/**
+ * Read the headers the message and determine, and store, its payload's length
+ *
+ * @param this The message
+ * @return Zero on success, negative on error (malformated message: unrecoverable state)
+ */
+#if defined(__GNUC__)
+__attribute__((pure))
+#endif
+static int get_payload_length(struct message* this)
+{
+ char* header;
+ size_t i;
+
+ for (i = 0; i < this->header_count; i++)
+ if (strstr(this->headers[i], "Length: ") == this->headers[i])
+ {
+ /* Store the message length. */
+ header = this->headers[i] + strlen("Length: ");
+ this->payload_size = (size_t)atol(header);
+
+ /* Do not except a length that is not correctly formated. */
+ for (; *header; header++)
+ if ((*header < '0') || ('9' < *header))
+ return -2; /* Malformated value, enters unrecoverable state. */
+
+ /* Stop searching for the ‘Length’ header, we have found and parsed it. */
+ break;
+ }
+
+ return 0;
+}
+
+
+/**
+ * Verify that a header is correctly formatted
+ *
+ * @param header The header, must be NUL-terminated
+ * @param length The length of the header
+ * @return Zero if valid, negative if invalid (malformated message: unrecoverable state)
+ */
+#if defined(__GNUC__)
+__attribute__((pure))
+#endif
+static int validate_header(const char* header, size_t length)
+{
+ char* p = memchr(header, ':', length * sizeof(char));
+
+ if (verify_utf8(header, 0) < 0)
+ /* Either the string is not UTF-8, or your are under an UTF-8 attack,
+ lets just call this unrecoverable because the client will not correct. */
+ return -2;
+
+ if ((p == NULL) || /* Buck you, rawmemchr should not segfault the program. */
+ (p[1] != ' ')) /* Also an invalid format. ' ' is mandated after the ':'. */
+ return -2;
+
+ return 0;
+}
+
+
+/**
+ * Remove the beginning of the read buffer
+ *
+ * @param this The message
+ * @param length The number of characters to remove
+ * @param update_ptr Whether to update the buffer pointer
+ */
+static void unbuffer_beginning(struct message* this, size_t length, int update_ptr)
+{
+ memmove(this->buffer, this->buffer + length, (this->buffer_ptr - length) * sizeof(char));
+ if (update_ptr)
+ this->buffer_ptr -= length;
+}
+
+
+/**
+ * Remove the header–payload delimiter from the buffer,
+ * get the payload's size and allocate the payload
+ *
+ * @param this The message
+ * @return The return value follows the rules of `message_read`
+ */
+static int initialise_payload(struct message* this)
+{
+ /* Remove the \n (end of empty line) we found from the buffer. */
+ unbuffer_beginning(this, 1, 1);
+
+ /* Get the length of the payload. */
+ if (get_payload_length(this) < 0)
+ return -2; /* Malformated value, enters unrecoverable state. */
+
+ /* Allocate the payload buffer. */
+ if (this->payload_size > 0)
+ if (!(this->payload = malloc(this->payload_size)))
+ return -1;
+
+ return 0;
+}
+
+
+/**
+ * Create a header from the buffer and store it
+ *
+ * @param this The message
+ * @param length The length of the header, including LF-termination
+ * @return The return value follows the rules of `message_read`
+ */
+static int store_header(struct message* this, size_t length)
+{
+ char* header;
+
+ /* Allocate the header. */
+ if (!(header = malloc(length))) /* Last char is a LF, which is substituted with NUL. */
+ return -1;
+ /* Copy the header data into the allocated header, */
+ memcpy(header, this->buffer, length * sizeof(char));
+ /* and NUL-terminate it. */
+ header[length - 1] = '\0';
+
+ /* Remove the header data from the read buffer. */
+ unbuffer_beginning(this, length, 1);
+
+ /* Make sure the the header syntax is correct so that
+ the program does not need to care about it. */
+ if (validate_header(header, length))
+ {
+ free(header);
+ return -2;
+ }
+
+ /* Store the header in the header list. */
+ this->headers[this->header_count++] = header;
+
+ return 0;
+}
+
+
+/**
+ * Continue reading from the socket into the buffer
+ *
+ * @param this The message
+ * @param fd The file descriptor of the socket
+ * @return The return value follows the rules of `message_read`
+ */
+static int continue_read(struct message* this, int fd)
+{
+ size_t n;
+ ssize_t got;
+ int r;
+
+ /* Figure out how much space we have left in the read buffer. */
+ n = this->buffer_size - this->buffer_ptr;
+
+ /* If we do not have too much left, */
+ if (n < 128)
+ {
+ /* grow the buffer, */
+ if ((r = extend_buffer(this)) < 0)
+ return r;
+
+ /* and recalculate how much space we have left. */
+ n = this->buffer_size - this->buffer_ptr;
+ }
+
+ /* Then read from the socket. */
+ errno = 0;
+ got = recv(fd, this->buffer + this->buffer_ptr, n, 0);
+ this->buffer_ptr += (size_t)(got < 0 ? 0 : got);
+ if (errno)
+ return -1;
+ if (got == 0)
+ {
+ errno = ECONNRESET;
+ return -1;
+ }
+
+ return 0;
+}
+
+
+/**
+ * Read the next message from a file descriptor
+ *
+ * @param this Memory slot in which to store the new message
+ * @param fd The file descriptor
+ * @return Non-zero on error or interruption, `errno` will be
+ * set accordingly. Destroy the message on error,
+ * be aware that the reading could have been
+ * interrupted by a signal rather than canonical error.
+ * If -2 is returned `errno` will not have been set,
+ * -2 indicates that the message is malformated,
+ * which is a state that cannot be recovered from.
+ */
+int message_read(struct message* this, int fd)
+{
+ size_t header_commit_buffer = 0;
+ int r;
+
+ /* If we are at stage 2, we are done and it is time to start over.
+ This is important because the function could have been interrupted. */
+ if (this->stage == 2)
+ {
+ reset_message(this);
+ this->stage = 0;
+ }
+
+ /* Read from file descriptor until we have a full message. */
+ for (;;)
+ {
+ char* p;
+ size_t length;
+
+ /* Stage 0: headers. */
+ /* Read all headers that we have stored into the read buffer. */
+ while ((this->stage == 0) &&
+ ((p = memchr(this->buffer, '\n', this->buffer_ptr * sizeof(char))) != NULL))
+ if ((length = (size_t)(p - this->buffer)))
+ {
+ /* We have found a header. */
+
+ /* On every eighth header found with this function call,
+ we prepare the header list for eight more headers so
+ that it does not need to be reallocated again and again. */
+ if (header_commit_buffer == 0)
+ if ((r = extend_headers(this, header_commit_buffer = 8)) < 0)
+ return r;
+
+ /* Create and store header. */
+ if ((r = store_header(this, length + 1)) < 0)
+ return r;
+ header_commit_buffer -= 1;
+ }
+ else
+ {
+ /* We have found an empty line, i.e. the end of the headers. */
+
+ /* Remove the header–payload delimiter from the buffer,
+ get the payload's size and allocate the payload. */
+ if ((r = initialise_payload(this)) < 0)
+ return r;
+
+ /* Mark end of stage, next stage is getting the payload. */
+ this->stage = 1;
+ }
+
+
+ /* Stage 1: payload. */
+ if ((this->stage == 1) && (this->payload_size > 0))
+ {
+ /* How much of the payload that has not yet been filled. */
+ size_t need = this->payload_size - this->payload_ptr;
+ /* How much we have of that what is needed. */
+ size_t move = this->buffer_ptr < need ? this->buffer_ptr : need;
+
+ /* Copy what we have, and remove it from the the read buffer. */
+ memcpy(this->payload + this->payload_ptr, this->buffer, move * sizeof(char));
+ unbuffer_beginning(this, move, 1);
+
+ /* Keep track of how much we have read. */
+ this->payload_ptr += move;
+ }
+ if ((this->stage == 1) && (this->payload_ptr == this->payload_size))
+ {
+ /* If we have filled the payload (or there was no payload),
+ mark the end of this stage, i.e. that the message is
+ complete, and return with success. */
+ this->stage = 2;
+ return 0;
+ }
+
+
+ /* If stage 1 was not completed. */
+
+ /* Continue reading from the socket into the buffer. */
+ if ((r = continue_read(this, fd)) < 0)
+ return r;
+ }
+}
+
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