good starting point, finished the guide

13 files changed, 550 insertions, 0 deletions

diff --git a/.vscode/c_cpp_properties.json b/.vscode/c_cpp_properties.json
new file mode 100644
index 0000000..9a0a2f5
--- /dev/null
+++ b/.vscode/c_cpp_properties.json
@@ -0,0 +1,19 @@
+{
+    "configurations": [
+        {
+            "name": "Mac",
+            "includePath": [
+                "${workspaceFolder}/**"
+            ],
+            "defines": [],
+            "macFrameworkPath": [
+                "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/System/Library/Frameworks"
+            ],
+            "compilerPath": "/usr/bin/clang",
+            "cStandard": "c17",
+            "cppStandard": "c++17",
+            "intelliSenseMode": "macos-clang-arm64"
+        }
+    ],
+    "version": 4
+}
\ No newline at end of file
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..5e808ed
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,13 @@
+CC      = gcc
+CFLAGS  = -std=c99 -target x86_64-apple-darwin20 -g 
+RM      = rm -f
+
+default: all
+
+all: server client
+
+server: server.c
+	$(CC) $(CFLAGS) -o server server.c
+
+client: client.c
+	$(CC) $(CFLAGS) -o client client.c
\ No newline at end of file
diff --git a/client b/client
new file mode 100755
index 0000000..2277b67
--- /dev/null
+++ b/client
diff --git a/client.c b/client.c
new file mode 100644
index 0000000..591d030
--- /dev/null
+++ b/client.c
@@ -0,0 +1,100 @@
+/*
+** client.c -- a stream socket client demo
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+#include <string.h>
+#include <netdb.h>
+#include <sys/types.h>
+#include <netinet/in.h>
+#include <sys/socket.h>
+
+#include <arpa/inet.h>
+
+#define PORT "3490" // the port client will be connecting to 
+
+#define MAXDATASIZE 100 // max number of bytes we can get at once 
+
+// get sockaddr, IPv4 or IPv6:
+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);
+}
+
+int main(int argc, char *argv[])
+{
+    int sockfd, numbytesrecv, numbytessent;  
+    char buf[MAXDATASIZE];
+    struct addrinfo hints, *servinfo, *p;
+    int rv;
+    char s[INET6_ADDRSTRLEN];
+
+    if (argc != 3) {
+        fprintf(stderr,"usage: client hostname\n");
+        exit(1);
+    }
+
+    memset(&hints, 0, sizeof hints);
+    hints.ai_family = AF_INET; // only IPv4
+    hints.ai_socktype = SOCK_STREAM;
+
+    if ((rv = getaddrinfo(argv[2], PORT, &hints, &servinfo)) != 0) {
+        fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv));
+        return 1;
+    }
+
+    // loop through all the results and connect to the first we can
+    for(p = servinfo; p != NULL; p = p->ai_next) {
+        if ((sockfd = socket(p->ai_family, p->ai_socktype,
+                p->ai_protocol)) == -1) {
+            perror("client: socket");
+            continue;
+        }
+
+        if (connect(sockfd, p->ai_addr, p->ai_addrlen) == -1) {
+            close(sockfd);
+            perror("client: connect");
+            continue;
+        }
+
+        break;
+    }
+
+    if (p == NULL) {
+        fprintf(stderr, "client: failed to connect\n");
+        return 2;
+    }
+
+    inet_ntop(p->ai_family, get_in_addr((struct sockaddr *)p->ai_addr),
+            s, sizeof s);
+    printf("client: connecting to %s\n", s);
+
+    freeaddrinfo(servinfo); // all done with this structure
+
+    if ((numbytesrecv = recv(sockfd, buf, MAXDATASIZE-1, 0)) == -1) {
+        perror("recv");
+        exit(1);
+    }
+
+    buf[numbytesrecv] = '\0';
+
+    printf("client: received '%s'\n",buf);
+
+    if ((numbytessent = send(sockfd, "Welcome", 7, 0)) == -1) {
+        perror("send");
+        exit(1);
+    }
+
+    buf[numbytessent] = '\0';
+
+    close(sockfd);
+
+    return 0;
+}
\ No newline at end of file
diff --git a/client.dSYM/Contents/Info.plist b/client.dSYM/Contents/Info.plist
new file mode 100644
index 0000000..d550748
--- /dev/null
+++ b/client.dSYM/Contents/Info.plist
@@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+	<dict>
+		<key>CFBundleDevelopmentRegion</key>
+		<string>English</string>
+		<key>CFBundleIdentifier</key>
+		<string>com.apple.xcode.dsym.client</string>
+		<key>CFBundleInfoDictionaryVersion</key>
+		<string>6.0</string>
+		<key>CFBundlePackageType</key>
+		<string>dSYM</string>
+		<key>CFBundleSignature</key>
+		<string>????</string>
+		<key>CFBundleShortVersionString</key>
+		<string>1.0</string>
+		<key>CFBundleVersion</key>
+		<string>1</string>
+	</dict>
+</plist>
diff --git a/client.dSYM/Contents/Resources/DWARF/client b/client.dSYM/Contents/Resources/DWARF/client
new file mode 100644
index 0000000..4d642ff
--- /dev/null
+++ b/client.dSYM/Contents/Resources/DWARF/client
diff --git a/listener.c b/listener.c
new file mode 100644
index 0000000..723cb1b
--- /dev/null
+++ b/listener.c
@@ -0,0 +1,95 @@
+/*
+** listener.c -- a datagram sockets "server" demo
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <netdb.h>
+
+#define MYPORT "4950"    // the port users will be connecting to
+
+#define MAXBUFLEN 100
+
+// get sockaddr, IPv4 or IPv6:
+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);
+}
+
+int main(void)
+{
+    int sockfd;
+    struct addrinfo hints, *servinfo, *p;
+    int rv;
+    int numbytes;
+    struct sockaddr_storage their_addr;
+    char buf[MAXBUFLEN];
+    socklen_t addr_len;
+    char s[INET6_ADDRSTRLEN];
+
+    memset(&hints, 0, sizeof hints);
+    hints.ai_family = AF_INET6; // set to AF_INET to use IPv4
+    hints.ai_socktype = SOCK_DGRAM;
+    hints.ai_flags = AI_PASSIVE; // use my IP
+
+    if ((rv = getaddrinfo(NULL, MYPORT, &hints, &servinfo)) != 0) {
+        fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv));
+        return 1;
+    }
+
+    // loop through all the results and bind to the first we can
+    for(p = servinfo; p != NULL; p = p->ai_next) {
+        if ((sockfd = socket(p->ai_family, p->ai_socktype,
+                p->ai_protocol)) == -1) {
+            perror("listener: socket");
+            continue;
+        }
+
+        if (bind(sockfd, p->ai_addr, p->ai_addrlen) == -1) {
+            close(sockfd);
+            perror("listener: bind");
+            continue;
+        }
+
+        break;
+    }
+
+    if (p == NULL) {
+        fprintf(stderr, "listener: failed to bind socket\n");
+        return 2;
+    }
+
+    freeaddrinfo(servinfo);
+
+    printf("listener: waiting to recvfrom...\n");
+
+    addr_len = sizeof their_addr;
+    if ((numbytes = recvfrom(sockfd, buf, MAXBUFLEN-1 , 0,
+        (struct sockaddr *)&their_addr, &addr_len)) == -1) {
+        perror("recvfrom");
+        exit(1);
+    }
+
+    printf("listener: got packet from %s\n",
+        inet_ntop(their_addr.ss_family,
+            get_in_addr((struct sockaddr *)&their_addr),
+            s, sizeof s));
+    printf("listener: packet is %d bytes long\n", numbytes);
+    buf[numbytes] = '\0';
+    printf("listener: packet contains \"%s\"\n", buf);
+
+    close(sockfd);
+
+    return 0;
+}
diff --git a/reference.c b/reference.c
new file mode 100644
index 0000000..1f5b74b
--- /dev/null
+++ b/reference.c
@@ -0,0 +1,72 @@
+#include <stdio.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netdb.h>
+#include <arpa/inet.h>
+#include <netinet/in.h>
+
+struct addrinfo {
+    int              ai_flags;     // AI_PASSIVE, AI_CANONNAME, etc.
+    int              ai_family;    // AF_INET, AF_INET6, AF_UNSPEC
+    int              ai_socktype;  // SOCK_STREAM, SOCK_DGRAM
+    int              ai_protocol;  // use 0 for "any"
+    size_t           ai_addrlen;   // size of ai_addr in bytes
+    struct sockaddr *ai_addr;      // struct sockaddr_in or _in6
+    char            *ai_canonname; // full canonical hostname
+
+    struct addrinfo *ai_next;      // linked list, next node
+};
+
+struct sockaddr {
+    unsigned short    sa_family;    // address family, AF_xxx
+    char              sa_data[14];  // 14 bytes of protocol address
+}; 
+
+struct sockaddr_in {
+    short int          sin_family;  // Address family, AF_INET
+    unsigned short int sin_port;    // Port number
+    struct in_addr     sin_addr;    // Internet address
+    unsigned char      sin_zero[8]; // Same size as struct sockaddr
+};
+
+// (IPv4 only--see struct in6_addr for IPv6)
+// Internet address (a structure for historical reasons)
+struct in_addr {
+    uint32_t s_addr; // that's a 32-bit int (4 bytes)
+};
+
+struct sockaddr_storage {
+    sa_family_t  ss_family;     // address family
+
+    // all this is padding, implementation specific, ignore it:
+    char      __ss_pad1[_SS_PAD1SIZE];
+    int64_t   __ss_align;
+    char      __ss_pad2[_SS_PAD2SIZE];
+};
+
+int getaddrinfo(const char *node,     // e.g. "www.example.com" or IP
+                const char *service,  // e.g. "http" or port number
+                const struct addrinfo *hints,
+                struct addrinfo **res);
+
+
+// sockets!
+#include <sys/types.h>
+#include <sys/socket.h>
+
+int socket(int domain, int type, int protocol); 
+
+int s;
+struct addrinfo hints, *res;
+
+// do the lookup
+// [pretend we already filled out the "hints" struct]
+getaddrinfo("www.example.com", "http", &hints, &res);
+
+// again, you should do error-checking on getaddrinfo(), and walk
+// the "res" linked list looking for valid entries instead of just
+// assuming the first one is good (like many of these examples do).
+// See the section on client/server for real examples.
+
+s = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
\ No newline at end of file
diff --git a/server b/server
new file mode 100755
index 0000000..4f78e6c
--- /dev/null
+++ b/server
diff --git a/server.c b/server.c
new file mode 100644
index 0000000..ea7d62c
--- /dev/null
+++ b/server.c
@@ -0,0 +1,144 @@
+/*
+** server.c -- a stream socket server demo
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <netdb.h>
+#include <arpa/inet.h>
+#include <sys/wait.h>
+#include <signal.h>
+
+#define PORT "3490"  // the port users will be connecting to
+
+#define BACKLOG 10   // how many pending connections queue will hold
+
+#define MAXDATASIZE 100 // max number of bytes we can get at once 
+
+
+void sigchld_handler(int s)
+{
+    // waitpid() might overwrite errno, so we save and restore it:
+    int saved_errno = errno;
+
+    while(waitpid(-1, NULL, WNOHANG) > 0);
+
+    errno = saved_errno;
+}
+
+
+// get sockaddr, IPv4 or IPv6:
+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);
+}
+
+int main(void)
+{
+    int sockfd, new_fd, numbytes;  // listen on sock_fd, new connection on new_fd
+    char buf[MAXDATASIZE];
+    struct addrinfo hints, *servinfo, *p;
+    struct sockaddr_storage their_addr; // connector's address information
+    socklen_t sin_size;
+    struct sigaction sa;
+    int yes=1;
+    char s[INET6_ADDRSTRLEN];
+    int rv;
+
+    memset(&hints, 0, sizeof hints);
+    hints.ai_family = AF_INET; // only IPv4
+    hints.ai_socktype = SOCK_STREAM;
+    hints.ai_flags = AI_PASSIVE; // use my IP
+
+    if ((rv = getaddrinfo(NULL, PORT, &hints, &servinfo)) != 0) {
+        fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv));
+        return 1;
+    }
+
+    // loop through all the results and bind to the first we can
+    for(p = servinfo; p != NULL; p = p->ai_next) {
+        if ((sockfd = socket(p->ai_family, p->ai_socktype,
+                p->ai_protocol)) == -1) {
+            perror("server: socket");
+            continue;
+        }
+
+        if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &yes,
+                sizeof(int)) == -1) {
+            perror("setsockopt");
+            exit(1);
+        }
+
+        if (bind(sockfd, p->ai_addr, p->ai_addrlen) == -1) {
+            close(sockfd);
+            perror("server: bind");
+            continue;
+        }
+
+        break;
+    }
+
+    freeaddrinfo(servinfo); // all done with this structure
+
+    if (p == NULL)  {
+        fprintf(stderr, "server: failed to bind\n");
+        exit(1);
+    }
+
+    if (listen(sockfd, BACKLOG) == -1) {
+        perror("listen");
+        exit(1);
+    }
+
+    sa.sa_handler = sigchld_handler; // reap all dead processes
+    sigemptyset(&sa.sa_mask);
+    sa.sa_flags = SA_RESTART;
+    if (sigaction(SIGCHLD, &sa, NULL) == -1) {
+        perror("sigaction");
+        exit(1);
+    }
+
+    printf("server: waiting for connections...\n");
+
+    while(1) {  // main accept() loop
+        sin_size = sizeof their_addr;
+        new_fd = accept(sockfd, (struct sockaddr *)&their_addr, &sin_size);
+        if (new_fd == -1) {
+            perror("accept");
+            continue;
+        }
+
+        inet_ntop(their_addr.ss_family,
+            get_in_addr((struct sockaddr *)&their_addr),
+            s, sizeof s);
+        printf("server: got connection from %s\n", s);
+
+        if (!fork()) { // this is the child process
+
+            close(sockfd); // child doesn't need the listener
+            if (send(new_fd, "Hello, world!", 13, 0) == -1)
+                perror("send");
+            // close(new_fd);
+            if ((numbytes = recv(new_fd, buf, MAXDATASIZE-1, 0)) == -1) {
+                perror("recv");
+                exit(1);
+            }
+            buf[numbytes] = '\0';
+            printf("server: received '%s'\n",buf);
+            exit(0);
+        }
+        close(new_fd);  // parent doesn't need this
+    }
+
+    return 0;
+}
\ No newline at end of file
diff --git a/server.dSYM/Contents/Info.plist b/server.dSYM/Contents/Info.plist
new file mode 100644
index 0000000..d2b6274
--- /dev/null
+++ b/server.dSYM/Contents/Info.plist
@@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+	<dict>
+		<key>CFBundleDevelopmentRegion</key>
+		<string>English</string>
+		<key>CFBundleIdentifier</key>
+		<string>com.apple.xcode.dsym.server</string>
+		<key>CFBundleInfoDictionaryVersion</key>
+		<string>6.0</string>
+		<key>CFBundlePackageType</key>
+		<string>dSYM</string>
+		<key>CFBundleSignature</key>
+		<string>????</string>
+		<key>CFBundleShortVersionString</key>
+		<string>1.0</string>
+		<key>CFBundleVersion</key>
+		<string>1</string>
+	</dict>
+</plist>
diff --git a/server.dSYM/Contents/Resources/DWARF/server b/server.dSYM/Contents/Resources/DWARF/server
new file mode 100644
index 0000000..22ad6d7
--- /dev/null
+++ b/server.dSYM/Contents/Resources/DWARF/server
diff --git a/talker.c b/talker.c
new file mode 100644
index 0000000..bb801e5
--- /dev/null
+++ b/talker.c
@@ -0,0 +1,67 @@
+/*
+** talker.c -- a datagram "client" demo
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <netdb.h>
+
+#define SERVERPORT "4950"    // the port users will be connecting to
+
+int main(int argc, char *argv[])
+{
+    int sockfd;
+    struct addrinfo hints, *servinfo, *p;
+    int rv;
+    int numbytes;
+
+    if (argc != 3) {
+        fprintf(stderr,"usage: talker hostname message\n");
+        exit(1);
+    }
+
+    memset(&hints, 0, sizeof hints);
+    hints.ai_family = AF_INET6; // set to AF_INET to use IPv4
+    hints.ai_socktype = SOCK_DGRAM;
+
+    if ((rv = getaddrinfo(argv[1], SERVERPORT, &hints, &servinfo)) != 0) {
+        fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv));
+        return 1;
+    }
+
+    // loop through all the results and make a socket
+    for(p = servinfo; p != NULL; p = p->ai_next) {
+        if ((sockfd = socket(p->ai_family, p->ai_socktype,
+                p->ai_protocol)) == -1) {
+            perror("talker: socket");
+            continue;
+        }
+
+        break;
+    }
+
+    if (p == NULL) {
+        fprintf(stderr, "talker: failed to create socket\n");
+        return 2;
+    }
+
+    if ((numbytes = sendto(sockfd, argv[2], strlen(argv[2]), 0,
+             p->ai_addr, p->ai_addrlen)) == -1) {
+        perror("talker: sendto");
+        exit(1);
+    }
+
+    freeaddrinfo(servinfo);
+
+    printf("talker: sent %d bytes to %s\n", numbytes, argv[1]);
+    close(sockfd);
+
+    return 0;
+}
\ No newline at end of file