Implement Server (#1)

- Generic Server struct
- TCP and UDP

Reviewed-on: #1

.gitea/workflows/jobs.yaml

@@ -14,7 +14,7 @@ jobs:
       - name: Install dependencies
         run: |
           sudo apt-get update
-          sudo apt-get install -y libbsd-dev cmake build-essential
+          sudo apt-get install -y libbsd-dev cmake build-essential netcat
 
       - name: Build and test
         run: |

.gitignore

@@ -5,4 +5,7 @@ compile_commands.json
 site
 libflint.so
 test
+tcptest
+testrunner
 .idea
+netmanual

CMakeLists.txt

@@ -2,6 +2,10 @@ cmake_minimum_required(VERSION 3.17)
 project(flint C)
 set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
 
+if ((${CMAKE_SYSTEM_NAME} STREQUAL "Linux"))
+    add_compile_definitions(flint __USE_XOPEN_EXTENDED)
+endif()
+
 set(CMAKE_C_STANDARD 99)
 include_directories(include)
 
@@ -17,16 +21,17 @@ set(SOURCES
         src/utility.c
         src/crypto.c
         src/parsing.c
+        src/network.c
 )
 
 if ((${CMAKE_SYSTEM_NAME} STREQUAL "Darwin"))
-    add_library(flint ${SOURCES} src/macos/macos.c)
+    add_library(flint ${SOURCES} src/macos.c)
 else()
     add_library(flint ${SOURCES})
 endif()
 
 if ((${CMAKE_SYSTEM_NAME} STREQUAL "Linux"))
-    target_link_libraries(flint bsd)
+    target_link_libraries(flint pthread bsd)
 endif()
 
 if(${CMAKE_PROJECT_NAME} STREQUAL flint)
@@ -34,8 +39,17 @@ if(${CMAKE_PROJECT_NAME} STREQUAL flint)
     target_include_directories(tests PRIVATE include)
 
     if (${CMAKE_SYSTEM_NAME} STREQUAL "Linux")
-        target_link_libraries(tests flint bsd)
+        target_link_libraries(tests flint pthread bsd)
     else()
-        target_link_libraries(tests flint)
+        target_link_libraries(tests flint pthread)
+    endif()
+
+    add_executable(netmanual tests/netmanual.c)
+    target_include_directories(netmanual PRIVATE include)
+
+    if (${CMAKE_SYSTEM_NAME} STREQUAL "Linux")
+        target_link_libraries(netmanual flint pthread bsd)
+    else()
+        target_link_libraries(netmanual flint pthread)
     endif()
 endif()

Makefile

@@ -1,32 +0,0 @@
-.PHONY : clean
-
-CFLAGS =		-std=c99 -Iinclude -pedantic -Wall -Wextra
-LDFLAGS =		-fPIC -shared
-
-TARGET = 	libflint.so
-SRC !=		ls src/*.c
-OBJ =			$(SRC:./src/$.c=./obj/%.o)
-
-PREFIX =	$(DESTDIR)/usr/local
-LIBDIR =	$(PREFIX)/lib
-
-all: $(TARGET)
-
-$(TARGET): $(OBJ)
-	cc $(CFLAGS) $(LDFLAGS) -o $(TARGET) $(OBJ)
-
-./obj/%.o: ./src/%.c
-	cc $(CFLAGS) -c $< -o $@
-
-install: $(TARGET)
-	cp $(TARGET) $(LIBDIR)
-
-uninstall:
-	rm -f $(LIBDIR)/$(TARGET)
-
-clean:
-	rm -f $(TARGET)
-	rm -f test
-
-test:
-	cc $(CFLAGS) -o test tests/tests.c src/*.c

build.sh

@@ -1,10 +0,0 @@
-#!/bin/sh -e
-
-# For building outside of CLion
-
-mkdir -p build
-cd build
-cmake ..
-make
-cp compile_commands.json ..
-cd

clanggen.sh

@@ -0,0 +1,17 @@
+#!/usr/bin/env sh
+
+set -e
+
+CFLAGS="-I./include -I/usr/local/include"
+
+rm -f compile_commands.json
+
+for f in $(find ./src -type f | grep -v macos); do
+  n=$(echo $f | grep -o '[^/]*$' | sed 's/c$/json/')
+  cc -MJ $n $CFLAGS -c $f
+done
+
+rm *.o
+sed -e '1s/^/[/' -e '$s/,$/]/' *.json > compile_commands.out
+rm *.json
+mv compile_commands.out compile_commands.json

docs/input.md

@@ -92,7 +92,8 @@ printf("%s\n", sp[0]); // Prints "Split"
 
 ### del_split
 
-Frees all memory used by `split()`. Just like `split`, it does not touch the original string
+Frees all memory used by `split()`. Just like `split`, it does not touch the original string.
+
 ```c
 void del_split(char **sp);
 
@@ -101,3 +102,19 @@ size_t sp_sz = 0;
 char **sp = split("Delete Me!", &sp_sz, " ");
 void del_split(sp);
 ```
+
+### capture_system
+
+Runs a command on the system shell and returns stdout as a string. `buffsize` is the size of 
+the returned buffer that holds `stdout`. Passing `0` to `buffsize` will use the default buffer size of `1024`.
+
+User is responsible for freeing the returned string.
+
+```c
+const char *capture_system(const char *cmd, int buffsize);
+
+/* Usage */
+const char *cap = capture_system("ls $HOME", 0);
+printf("%s\n", cap);
+free(cap);
+```

docs/network.md

@@ -0,0 +1,106 @@
+# network
+
+This module provides a generic `Server` type that abstracts away the setup and teardown of a socket
+
+## Enums
+
+### ServerType
+
+Types of servers. Currently supports TCP and UDP, will eventually add UNIX sockets.
+
+```c
+typedef enum ServerType {
+    SERVERTYPE_TCP,
+    SERVERTYPE_UDP
+} ServerType;
+```
+
+## Structs
+
+### Server
+
+Server is a generic abstraction over sockets. The type of the server is defined by `server_type`.
+
+```c
+typedef struct Server {
+    ServerType server_type;
+    int fd;
+    int port;
+    void (*handler)(struct Server *s);
+} Server;
+```
+
+## Functions
+
+### new_server
+
+Create a `Server*`. User is responsible for freeing the memory.
+
+```c
+Server *new_server(ServerType type, const char *port, void(handler)(Server *s));
+```
+
+### delete_server
+
+Frees the memory allocated for `Server*` and sets the pointer to `NULL`.
+
+```c
+void delete_server(Server *s);
+```
+
+### serve
+
+Starts up the server. `backlog_size` is the size of the backlog buffer for the underlying socket. Use the macro 
+`DEFAULT_BACKLOG_SIZE` or pass `0` to use a reasonable default.
+
+```c
+int serve(Server *s, int backlog_size);
+```
+
+### get_in_addr
+
+Convenience method to get an IP address from a `struct sockaddr_storage` of either IPV4 or IPV6. 
+
+```c
+void *get_in_addr(struct sockaddr *sa);
+
+/* Usage */
+struct sockaddr_storage client_addr;
+socklen_t client_addr_sz = sizeof(client_addr); 
+char buf[33];
+
+if (new_fd = accept(s->fd, (struct sockaddr *)&client_addr, &client_addr_sz) == -1) {
+    /* error handling */
+}
+inet_ntop(client_addr.ss_family, get_in_addr((struct sockaddr *)&client_addr), buf, 32);
+printf("Received connection from %s\n", buf);
+
+```
+
+### handler_tcp_echo
+
+An example handler for a multithreaded tcp echo server.
+
+```c
+void handler_tcp_echo(Server *s);
+
+/* Usage */
+#include "lfnetwork.h"
+
+int main(int argc, char **argv) {
+    Server *server = new_server(SERVERTYPE_TCP, "80", handler_tcp_echo);
+    serve(server, DEFAULT_BACKLOG);
+    delete_server(server);
+}
+```
+
+## Macros
+
+### DEFAULT_BACKLOG_SIZE
+
+A default size for the socket's backlog buffer. `5` is a standard default size, providing some backlog but not
+enough to make huge buffers for each socket
+
+```c
+#define DEFAULT_BACKLOG_SIZE 5
+```

include/lfinput.h

@@ -17,4 +17,8 @@ void del_split(char **);
 
 void del_lines(char **);
 
+#define DEFAULT_CAPTURE_SYSTEM_BUFSIZE 1024
+
+const char *capture_system(const char *cmd, int buf_sz);
+
 #endif // LIBFLINT_INPUT_H

include/lfnetwork.h

@@ -0,0 +1,28 @@
+#ifndef LIBFLINT_NET_H
+#define LIBFLINT_NET_H
+
+#include <netdb.h>
+
+typedef enum ServerType {
+    SERVERTYPE_TCP,
+    SERVERTYPE_UDP
+} ServerType;
+
+typedef struct Server {
+    ServerType server_type;
+    int fd;
+    int port;
+    void (*handler)(struct Server *s);
+} Server;
+
+#define DEFAULT_BACKLOG 5
+
+Server *new_server(ServerType type, const char *port, void(handler)(Server *s));
+void delete_server(Server *s);
+int serve(Server *s, int backlog_size);
+void *get_in_addr(struct sockaddr *sa);
+
+// Example handlers
+void handler_tcp_echo(Server *s);
+
+#endif //LIBFLINT_NET_H

run_tests.sh

@@ -0,0 +1,12 @@
+set -e
+
+#./testrunner
+./tcptest &
+tcpout=$(echo "hello" | nc localhost 18632)
+echo "tcpout: $tcpout" 
+if [ "$tcpout" != "TEST SEND" ]; then
+ echo "Error: \"$tcpout\" != \"TEST SEND\""
+ exit 1
+fi
+
+exit 0

src/input.c

@@ -2,6 +2,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <limits.h>
+#include <errno.h>
 
 #ifdef __linux__
 
@@ -121,3 +122,18 @@ void del_split(char **sp) {
 void del_lines(char **lines) {
     del_split(lines);
 }
+
+const char *capture_system(const char *cmd, int buf_sz) {
+    if (buf_sz == 0) {
+        buf_sz = DEFAULT_CAPTURE_SYSTEM_BUFSIZE;
+    }
+    char *buf = malloc(buf_sz);
+    FILE *tmp = popen(cmd, "r");
+    if (tmp == NULL) {
+        fprintf(stderr, "libflint: failed to open FILE *tmp in capture_system. Errno: %d\n", errno);
+        free(buf);
+        return NULL;
+    }
+    fgets(buf, buf_sz, tmp);
+    return buf;
+}

src/network.c

@@ -0,0 +1,150 @@
+#include <errno.h>
+#include <string.h>
+#include <stdlib.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <arpa/inet.h>
+#include <sys/wait.h>
+#include <netdb.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <signal.h>
+#include <pthread.h>
+
+#include "lfnetwork.h"
+
+static void sighandler(int s) {
+    int saved_errno = errno;
+    while (waitpid(-1, NULL, WNOHANG) > 0);
+    errno = saved_errno;
+}
+
+void *get_in_addr(struct sockaddr *sa)
+{
+    if (sa->sa_family == AF_INET) {
+        return &(((struct sockaddr_in*)sa)->sin_addr);
+    }
+
+    return &(((struct sockaddr_in6*)sa)->sin6_addr);
+}
+
+Server *new_server(ServerType type, const char *port, void(handler)(Server *s)) {
+    Server *s = (Server *)malloc(sizeof(Server));
+    if (s == NULL) {
+        return NULL;
+    }
+    s->server_type = type;
+    s->handler = handler;
+
+    struct addrinfo *addr = NULL;
+    if (getaddrinfo(NULL, port, NULL, &addr) != 0) {
+        free(s);
+        return NULL;
+    }
+    s->port = (int)strtol(port, NULL, 10);
+
+    int socktype = 0;
+    switch (type) {
+    case SERVERTYPE_TCP:
+        socktype = SOCK_STREAM;
+        break;
+    case SERVERTYPE_UDP:
+        socktype = SOCK_DGRAM;
+        break;
+    }
+
+    struct addrinfo *p;
+    for (p = addr; p != NULL; p = p->ai_next) {
+        s->fd = socket(AF_INET, socktype, 0);
+        if (s->fd == -1) {
+            continue;
+        }
+
+        if (bind(s->fd, p->ai_addr, p->ai_addrlen) != 0) {
+            close(s->fd);
+            continue;
+        }
+
+        break;
+    }
+
+    if (p == NULL) {
+        fprintf(stderr, "Failed to bind\n");
+        free(s);
+        return NULL;
+    }
+
+    freeaddrinfo(addr);
+    return s;
+}
+
+void delete_server(Server *s) {
+    free(s);
+    s = NULL;
+}
+
+int serve(Server *s, int backlog_size) {
+    if (backlog_size == 0) {
+        backlog_size = DEFAULT_BACKLOG;
+    }
+
+    if (listen(s->fd, backlog_size) != 0) {
+        return 1;
+    }
+
+    // Linux doesn't handle SA_RESTART properly, and I don't know about Windows (nor do I care)
+    // This is just for macOS and BSDs
+    #if !defined(__linux__) && !defined(_WIN32)
+    struct sigaction sa;
+    sa.sa_handler = sighandler; 
+    sa.sa_flags = SA_RESTART;
+    if (sigaction(SIGCHLD, &sa, NULL) == -1) {
+        fprintf(stderr, "Failed to set sigaction\n");
+        return 1;
+    }
+    #endif
+
+    s->handler(s);
+
+    return 0;
+}
+
+static void *tcp_echo_thread(void *vargp) {
+    while (1) {
+        char recv_buf[256];
+        int fd = *(int *) vargp;
+
+        int r = (int)recv(fd, recv_buf, 256, 0);
+        if (r < 1) {
+            if (r == -1) {
+                fprintf(stderr, "Failed to recv. Errno: %d\n", errno);
+            }
+            close(fd);
+            break;
+        }
+
+        if (send(fd, recv_buf, strlen(recv_buf), 0) == -1) {
+            fprintf(stderr, "Failed to send echo. Errno: %d\n", errno);
+            close(fd);
+            break;
+        }
+    }
+}
+
+void handler_tcp_echo(Server *s) {
+    while (1) {
+        struct sockaddr_storage client_addr;
+        socklen_t client_addr_sz = sizeof(client_addr);
+        int new_fd = accept(s->fd, (struct sockaddr *)&client_addr, &client_addr_sz);
+        if (new_fd == -1) {
+            fprintf(stderr, "failed to accept. Errno: %d\n", errno);
+            continue;
+        }
+
+        pthread_t srv_tid;
+        pthread_attr_t attr;
+        pthread_attr_init(&attr);
+        pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
+        pthread_create(&srv_tid, &attr, tcp_echo_thread, &new_fd);
+    }
+}

tests/netmanual.c

@@ -0,0 +1,7 @@
+#include "lfnetwork.h"
+
+int main(int argc, char **argv) {
+    Server *server = new_server(SERVERTYPE_TCP, "18632", handler_tcp_echo);
+    serve(server, DEFAULT_BACKLOG);
+    delete_server(server);
+}

tests/tests.c

@@ -2,8 +2,11 @@
 #include <stdlib.h>
 #include <assert.h>
 #include <unistd.h>
+#include <arpa/inet.h>
+#include <pthread.h>
 
 #include "lflinkedlist.h"
+#include "lfnetwork.h"
 #include "lfset.h"
 #include "lfstack.h"
 #include "lfbinarytree.h"
@@ -12,6 +15,7 @@
 #include "lfstring.h"
 #include "lfcrypto.h"
 #include "lfparsing.h"
+#include "lfinput.h"
 
 #if defined(__APPLE__) || defined(__MACH__)
 #include "lfmacos.h"
@@ -395,6 +399,60 @@ void test_parsing() {
     printf("Passes all parsing tests\n");
 }
 
+#define NET_MSG "TEST SEND"
+
+void tcp_test_handler(Server *s) {
+    struct sockaddr_storage client_addr;
+    socklen_t client_addr_sz = sizeof(client_addr);
+    int new_fd = accept(s->fd, (struct sockaddr *)&client_addr, &client_addr_sz);
+    assert(new_fd != -1);
+    assert(send(new_fd, NET_MSG, 10, 0) != -1);
+    close(new_fd);
+}
+
+void *tcp_server_thread(void *vargp) {
+    Server *server = new_server(SERVERTYPE_TCP, "18632", tcp_test_handler);
+    serve(server, DEFAULT_BACKLOG);
+    delete_server(server);
+}
+
+void udp_test_handler(Server *s) {
+    struct sockaddr_storage client_addr;
+    socklen_t client_addr_sz = sizeof(client_addr);
+    char recv_buf[128];
+
+    int r = (int)recvfrom(s->fd, recv_buf, 128, 0, (struct sockaddr*)&client_addr, &client_addr_sz);
+    assert(r > 0);
+    assert(strcmp(recv_buf, NET_MSG) == 0);
+}
+
+void *udp_server_thread(void *vargp) {
+    Server *server = new_server(SERVERTYPE_UDP, "18633", udp_test_handler);
+    serve(server, DEFAULT_BACKLOG);
+    delete_server(server);
+}
+
+void test_network() {
+    printf("\n--- NETWORK TEST ---\n");
+    pthread_t srv_tid;
+    pthread_create(&srv_tid, NULL, tcp_server_thread, NULL);
+
+    sleep(1);
+    const char *s = capture_system("echo hello | nc localhost 18632", 0);
+    assert(strcmp(s, NET_MSG) == 0);
+    free((char *)s);
+
+    pthread_join(srv_tid, NULL);
+    printf("Passed TCP test\n");
+
+    pthread_create(&srv_tid, NULL, udp_server_thread, NULL);
+    sleep(1);
+    system("echo hello | nc localhost 18633");
+
+    pthread_join(srv_tid, NULL);
+    printf("Passed UDP test\n");
+}
+
 #if defined(__APPLE__) || defined(__MACH__)
 void test_macos() {
     printf("\n--- macOS TEST ---\n");
@@ -420,6 +478,7 @@ int main() {
     test_string();
     test_crypto();
     test_parsing();
+    test_network();
 
 #if defined(__APPLE__) || defined(__MACH__)
     test_macos();