mirror of
https://github.com/cesanta/mongoose.git
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135 lines
3.1 KiB
C
135 lines
3.1 KiB
C
// Copyright (c) 2026 Cesanta Software Limited
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// All rights reserved
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//
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// This is an implementation of the simple TCP echo server which supports
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// multiple concurrent connections, using BSD sockets API.
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#include "mongoose.h"
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#include <stdio.h>
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#include <stdlib.h>
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struct echo_server {
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int sock;
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struct echo_client {
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struct echo_client *next;
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int sock;
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size_t len, sent;
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char buf[128];
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} *clients;
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};
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static struct echo_server s_server = {-1, NULL};
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static int echo_nonblock(int fd) {
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int flags = fcntl(fd, F_GETFL, 0);
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return flags >= 0 && fcntl(fd, F_SETFL, flags | O_NONBLOCK) == 0;
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}
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static void echo_remove(struct echo_client **p) {
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struct echo_client *c = *p;
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*p = c->next;
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close(c->sock);
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free(c);
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}
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int echo_init(uint16_t port) {
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struct sockaddr_in sa = {
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.sin_family = AF_INET,
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.sin_port = htons(port),
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.sin_addr = {.s_addr = INADDR_ANY},
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};
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int fd = socket(AF_INET, SOCK_STREAM, 0);
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if (fd < 0 || !echo_nonblock(fd) ||
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bind(fd, (struct sockaddr *) &sa, sizeof(sa)) < 0 || listen(fd, 3) < 0) {
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printf("BSD echo init: %d\n", errno);
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if (fd >= 0) close(fd);
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return 0;
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}
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s_server.sock = fd;
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printf("BSD echo server on port %hu\n", port);
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return 1;
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}
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void echo_poll(void) {
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struct echo_server *s = &s_server;
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struct echo_client *c, **p;
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int maxfd, n;
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fd_set r, w;
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if (s->sock < 0) return;
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maxfd = s->sock;
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FD_ZERO(&r);
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FD_ZERO(&w);
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FD_SET(s->sock, &r);
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for (c = s->clients; c != NULL; c = c->next) {
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if (c->len == c->sent)
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FD_SET(c->sock, &r);
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else
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FD_SET(c->sock, &w);
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if (c->sock > maxfd) maxfd = c->sock;
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}
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if (select(maxfd + 1, &r, &w, NULL, NULL) <= 0) return;
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if (FD_ISSET(s->sock, &r)) {
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struct sockaddr_in sa;
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socklen_t len = sizeof(sa);
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int fd = accept(s->sock, (struct sockaddr *) &sa, &len);
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if (fd >= 0) {
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c = (struct echo_client *) calloc(1, sizeof(*c));
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if (c == NULL || !echo_nonblock(fd)) {
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printf("BSD echo accept: %d\n", c == NULL ? ENOMEM : errno);
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close(fd);
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free(c);
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} else {
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c->sock = fd;
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c->next = s->clients;
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s->clients = c;
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}
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}
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}
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p = &s->clients;
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while (*p != NULL) {
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c = *p;
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if (c->sent < c->len && FD_ISSET(c->sock, &w)) {
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n = (int) send(c->sock, c->buf + c->sent, c->len - c->sent, 0);
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if (n > 0) c->sent += (size_t) n;
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if (n < 0 && errno != EAGAIN && errno != EWOULDBLOCK) {
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echo_remove(p);
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continue;
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}
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}
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if (c->sent == c->len && FD_ISSET(c->sock, &r)) {
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n = (int) recv(c->sock, c->buf, sizeof(c->buf), 0);
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if (n > 0) c->len = (size_t) n, c->sent = 0;
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if (n == 0 || (n < 0 && errno != EAGAIN && errno != EWOULDBLOCK)) {
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echo_remove(p);
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continue;
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}
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}
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if (c->sent == c->len) c->len = c->sent = 0;
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p = &c->next;
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}
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}
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// On desktop, build with -DMAIN flag to include main().
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// On embedded system, run this code in your main() function
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#ifdef MAIN
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int main(void) {
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struct mg_mgr mgr;
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mg_mgr_init(&mgr);
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echo_init(1234);
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for (;;) {
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mg_mgr_poll(&mgr, 1);
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echo_poll();
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}
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return 0;
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}
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#endif
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