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/* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ *
* OHMYCGI *
* 2021 by Max Christian Pohle <max@coderonline.de> *
* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */
// {{{ INCLUDES
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <err.h>
#include <errno.h>
#include <arpa/inet.h>
#include <fcntl.h>
#include <sys/sendfile.h>
#include <sys/stat.h>
// #include <pthread.h> // maybe later
// }}}
// {{{ MACROS
#define EWOULDBLOCK_DELAY 100
#define READ_BUFFER_LENGTH 9000 // jumboframe?
#define POST_DATA_MAX_LENGTH 18000
#define DEBUG_SLEEP_TIME 50000
#ifndef DEBUG
#define DEBUG(X, ...) // (X, ...)
#else
#include <stdarg.h>
static inline int verbose(const char * format, ...) {
va_list va; va_start(va, format); usleep(DEBUG_SLEEP_TIME); return vprintf(format, va);
}
#undef DEBUG
#define DEBUG verbose
#endif
// }}}
typedef struct {
int newline_length; // lenght of one newline in bytes (\n has 1, CR/LF has 2)
char * method;
char * boundary;
size_t boundary_size;
char * content_type;
char * content_disposition;
char * url;
} Http_Header;
void send_answer(int fd_socket, Http_Header * http_header) {
FILE * f = fdopen((size_t) fd_socket, "w");
fputs("HTTP/1.0 200 OK\n", f);
fputs("content-type: text/plain\n\n", f);
fflush(f);
int file = open(&http_header->url[1], O_RDONLY);
if(0 < file) {
struct stat stat;
fstat(file, &stat);
sendfile (fileno(f), file, NULL, stat.st_size);
} else {
fprintf(f, "could not open file \"%s\"\n", &http_header->url[1]);
}
fclose(f);
// fputs("<html>", f);
// fputs("<head>", f);
// fputs("<title>test</title>", f);
// fputs("<style>label { display:block }</style>", f);
// fputs("</head>", f);
// fputs("<form action=\"/\" method=\"post\" enctype=\"multipart/form-data\">", f);
// fputs("<label>Line1<br/>\n", f);
// fputs("<textarea type=\"text\" name=\"text\"></textarea>", f);
// fputs("</label><br/>\n", f);
// fputs("<input type=\"file\" name=\"okay\" value=\"ok\" />", f);
// fputs("<input type=\"submit\" name=\"okay\" value=\"ok\" />", f);
// fputs("</form>", f);
// fputs("</html>", f);
}
int read_everything(FILE * f_r, FILE * output) {
const int read_buffer_length = READ_BUFFER_LENGTH;
char read_buffer[read_buffer_length];
for(size_t size = -2 ; ; size = fread(read_buffer, 1, read_buffer_length, f_r)) {
if(-2 == size || (-1 == size && EWOULDBLOCK == errno)) {
usleep(EWOULDBLOCK_DELAY); // try again a little later
continue;
}
fwrite(read_buffer, read_buffer_length, 1, output);
if (read_buffer_length > POST_DATA_MAX_LENGTH)
return EXIT_FAILURE;
if (size < read_buffer_length) { // I expect one nmemb of data
break;
}
}
fflush(output);
return EXIT_SUCCESS;
}
void * next_customer(size_t new_socket) {
FILE * f_r = fdopen((size_t) new_socket, "r");
char * output_buffer = NULL;
size_t output_buffer_length = 0;
FILE * output = open_memstream(&output_buffer, &output_buffer_length);
DEBUG("\n\n########################################## Content Reader [%d]\n", f_r);
read_everything(f_r, output);
shutdown(new_socket, SHUT_RD); // shutdown the reading half of the connection
DEBUG("\n\n########################################## Content Parser\n");
char * start = output_buffer;
char * end = NULL;
char * search = "\r\n";
Http_Header http_header = {0};
char * name = NULL;
while(NULL != (end = strpbrk(start, search))) {
size_t matchlen = strspn(end, search);
switch(end[0]) {
case ':':
end[0] = '\0'; // {{{ remember header 'names' and search for the value
end++;
name = start;
if (0 == strcasecmp("Content-Type", start)) {
search = "\r\n;";
} else {
search = "\r\n";
} // }}}
break;
case ';':
start += strspn(start, "; "); // {{{ find the form-data boundary in the main header
const char s_multipart_form_data[] = "boundary=";
if(NULL == http_header.boundary && 0 < strcasecmp(start, s_multipart_form_data))
{
http_header.boundary = end + sizeof(s_multipart_form_data) + 1;
http_header.boundary += strspn(http_header.boundary, "-");
DEBUG("> Boundary found, now looking where it ends...\n");
search = "\r\n";
continue;
} /// }}}
break;
case '\r': // fallthrough
case '\n':
// {{{ newlines are special: sometimes content parts follow and sometimes headers, guess what...
end[0] = '\0';
search = ":"; // we will continue to search for headers
if(NULL == name) {
if(NULL == http_header.method) {
DEBUG("[%ld]> HTTP REQUEST LINE :: %s \n", matchlen, start);
end[0] = '\0';
while(NULL != (start = memchr(start, ' ', end - start))) {
if(NULL == http_header.url)
http_header.url = ++start;
else
start[0] = '\0';
}
http_header.method = start;
http_header.newline_length = matchlen;
} else {
DEBUG("[...]\n"); // if we want to intentially skip something, we land here by setting name = NUL;
break;
}
} else { // we know that name is not NULL and can work with it
if (0 == strcasecmp("Content-Disposition", name))
{ http_header.content_disposition = start; }
} // }}}
DEBUG("\033[32m[%ld]> '% 20s' = '%s'\033[0m\n", matchlen, name, start);
// {{{ check if a http header ended (e.g. two newlines)
if(matchlen > http_header.newline_length) {
DEBUG("> END HEADERS, because there were %d newlines; boundary='%s'[%ld]\n", matchlen / http_header.newline_length, http_header.boundary, http_header.boundary_size);
end += matchlen;
// if it was the first header, we calculate the boundary size and expect more headers to come after a boundary
if(http_header.boundary && http_header.boundary_size == 0) {
DEBUG("================================================================================\n");
http_header.boundary_size = strlen(http_header.boundary);
// skip the first header and boundary...
start = end;
start += strspn(start, "-");
start += http_header.boundary_size;
start += http_header.newline_length;
continue;
} else {
char * content_start = end;
while(1)
{
size_t size_remaining = (size_t) output_buffer_length - (end - output_buffer) - 1;
DEBUG("%ld remaining.\n", size_remaining);
if(size_remaining <= 0) {
DEBUG("> not even the boundary would fit in that what is left.\n");
break;
}
if(NULL == (end = memchr((void*) end, '-', size_remaining))) {
DEBUG("no further '-' found\n");
break;
}
char * content_end = end - http_header.newline_length;
end += strspn(end, "-");
if(0 == strncmp(end, http_header.boundary, http_header.boundary_size)) {
size_t file_size = content_end - content_start;
DEBUG("> Content ends here, size of the last file is %ld.", file_size);
end += http_header.boundary_size;
matchlen = strspn(end, "\r\n");
DEBUG("> end is at %p, matchlen is %ld\n", end, matchlen);
search = ":";
break;
} else {
end = end + 1;
}
}
}
break;
} // }}} if condition after a header
} // switch
if(NULL == end)
break;
else
start = end + matchlen;
}
DEBUG("> sending answer...");
send_answer(new_socket, &http_header);
DEBUG("> answer sent.");
fclose(f_r);
fclose(output);
free(output_buffer);
return NULL;
}
int serve(int server_fd)
{
struct sockaddr_in address;
socklen_t address_len = sizeof(address);
DEBUG("waiting for connections on server file descriptor %d", server_fd);
size_t new_socket = -1;
while(-1 != (new_socket = accept(server_fd, (struct sockaddr*) &address, &address_len)))
{
DEBUG("> Client %ld is connected via port %d", new_socket, address.sin_port);
// set non blocking mode...
fcntl(
(size_t) new_socket,
F_SETFL,
fcntl((size_t) new_socket, F_GETFL) | O_NONBLOCK
);
next_customer(new_socket);
#ifdef VALGRIND
break; // only run once, so that valgrind can test allocations&frees
#endif
}
err(errno, "error serving");
close(server_fd);
}
#define PORT 8080
int main(int argc, char const *argv[])
{
int server_fd = -1, opt = 1;
struct sockaddr_in address = {
.sin_family = AF_INET,
.sin_addr.s_addr = INADDR_ANY,
.sin_port = htons(PORT)
};
// I <3 C
0 == (server_fd = socket(AF_INET, SOCK_STREAM, 0))
? err(errno, NULL)
: setsockopt(server_fd, SOL_SOCKET, SO_REUSEADDR | SO_REUSEPORT, &opt, sizeof(opt))
? err(errno, "setsockopt failed on socket with fileno %d", server_fd)
: bind(server_fd, (struct sockaddr*) &address, sizeof(address))
? err(errno, NULL)
: listen(server_fd, SOMAXCONN)
? err(errno, NULL)
: serve(server_fd)
? err(errno, NULL)
: exit(EXIT_SUCCESS)
; return EXIT_FAILURE;
}
// vim: shiftwidth=2 tabstop=2 number foldmethod=marker
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