diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/libmdsserver/mds-message.c | 67 |
1 files changed, 61 insertions, 6 deletions
diff --git a/src/libmdsserver/mds-message.c b/src/libmdsserver/mds-message.c index ca2d1a4..3d44e19 100644 --- a/src/libmdsserver/mds-message.c +++ b/src/libmdsserver/mds-message.c @@ -90,6 +90,8 @@ int mds_message_read(mds_message_t* this, int fd) { size_t header_commit_buffer = 0; + /* If we are at stage 2, we are done and it is time to start over. + This is important because the function coul have been interrupted. */ if (this->stage == 2) { if (this->headers != NULL) @@ -110,42 +112,64 @@ int mds_message_read(mds_message_t* this, int fd) this->stage = 0; } + /* Read from file descriptor until we have a full message. */ for (;;) { size_t n, i; ssize_t got; char* p; + /* Stage 0: headers. */ if (this->stage == 0) + /* Read all headers that we have stored into the read buffer. */ while ((p = memchr(this->buffer, '\n', this->buffer_ptr)) != NULL) { size_t len = (size_t)(p - this->buffer) + 1; char* header; + /* We have found an empty line, i.e. the end of the headers.*/ if (len == 0) { + /* Remove the \n (end of empty line) we found from the buffer. */ memmove(this->buffer, this->buffer + 1, this->buffer_ptr -= 1); + + /* Get the length of the payload. */ 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)atoll(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; } - this->stage = 1; + /* Allocate the payload buffer. */ if (this->payload_size > 0) { this->payload = malloc(this->payload_size * sizeof(char)); if (this->payload == NULL) return -1; } + + /* Mark end of stage, next stage is getting the payload. */ + this->stage = 1; + + /* Stop searching for headers. */ break; } + /* Head have found a header. */ + + /* One every eighth heaer 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) { header_commit_buffer = 8; @@ -168,12 +192,20 @@ int mds_message_read(mds_message_t* this, int fd) } } + /* Allocat the header.*/ header = malloc(len * sizeof(char)); if (header == NULL) return -1; + /* Copy the header data into the allocated header, */ memcpy(header, this->buffer, len); + /* and NUL-terminate it. */ header[len - 1] = '\0'; + + /* Remove the header data from the read buffer. */ memmove(this->buffer, this->buffer + len, this->buffer_ptr -= len); + + /* Make sure the the header syntex is correct so the the + program does not need to care about it. */ if ((p = memchr(header, ':', len)) == NULL) { /* Buck you, rawmemchr should not segfault the program. */ @@ -185,31 +217,53 @@ int mds_message_read(mds_message_t* this, int fd) free(header); return -2; } + + /* Store the header in the heaer list. */ this->headers[this->header_count++] = header; header_commit_buffer -= 1; } + /* Stage 1: payload. */ if ((this->stage == 1) && (this->payload_ptr > 0)) { + /* How much of the payload that has not yet been filled. */ size_t need = this->payload_size - this->payload_ptr; if (this->buffer_ptr <= need) + /* If we have everything that we need, just copy it into the payload buffer. */ memcpy(this->payload + this->payload_ptr, this->buffer, this->buffer_ptr); else { + /* Otherwise, copy what we have, and remove it from the the read buffer. */ memcpy(this->payload + this->payload_ptr, this->buffer, need); memmove(this->buffer, this->buffer + need, this->buffer_ptr - need); } + + /* Keep track of how much we have read. */ this->payload_ptr += this->buffer_ptr; - this->buffer_ptr = 0; + if (this->buffer_ptr <= need) + /* Reset the read pointer as the read buffer is empty now. */ + this->buffer_ptr = 0; + else + /* But if we head left over data that is for the next message, + just move the pointer back as much as we read. (Which is + actually what we do even we did not have excess data.) */ + this->buffer_ptr -= needed; + + /* If we have filled the payload, make the end of this stage, + i.e. that the message is complete, and return with success. */ if (this->payload_ptr == this->payload_size) { - this->stage = 3; - break; + this->stage = 2; + return 0; } } + /* If stage 1 was not completed. */ + + /* 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, grow the buffer, */ if (n < 128) { char* old_buffer = this->buffer; @@ -221,9 +275,12 @@ int mds_message_read(mds_message_t* this, int fd) this->buffer_size >>= 1; return -1; } + + /* and recalculate how much space we have left. */ n = this->buffer_size - this->buffer_ptr; } + /* Then read from the file descriptor. */ errno = 0; got = read(fd, this->buffer + this->buffer_ptr, n); if (errno) @@ -232,8 +289,6 @@ int mds_message_read(mds_message_t* this, int fd) return -1; } } - - return 0; } |